#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <getopt.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <dirent.h>
#include <errno.h>

#include <stdint.h>
#include <stdarg.h>
#include <limits.h>

#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
#include <libavutil/avutil.h>
#include <libavutil/log.h>
#include <libavutil/channel_layout.h>
#include <libavutil/samplefmt.h>
#include <libavutil/frame.h>

#define FFT_SIZE_DEFAULT  4096
#define THRESHOLD_DEFAULT 50
#define MAX_ANALYSIS_SECS 60
#define OVERLAP_FACTOR    2

#define ANSI_RESET   "\033[0m"
#define ANSI_BOLD    "\033[1m"
#define ANSI_DIM     "\033[2m"
#define ANSI_RED     "\033[31m"
#define ANSI_GREEN   "\033[32m"
#define ANSI_YELLOW  "\033[33m"
#define ANSI_BLUE    "\033[34m"
#define ANSI_MAGENTA "\033[35m"
#define ANSI_CYAN    "\033[36m"
#define ANSI_BRIGHT_RED "\033[91m"
#define ANSI_BG_GREY "\033[48;5;235m"

typedef struct {
    double *power;
    int     count;
    int     sample_rate;
    int     channels;
    int     fft_size;
} Analyzer;

static void analyzer_init(Analyzer *a, int sample_rate, int channels, int fft_size)
{
    a->power       = calloc(fft_size / 2, sizeof(double));
    a->count       = 0;
    a->sample_rate = sample_rate;
    a->channels    = channels;
    a->fft_size    = fft_size;
}

static void analyzer_free(Analyzer *a)
{
    free(a->power);
    a->power = NULL;
}

static void apply_hann(double *buf, int n)
{
    for (int i = 0; i < n; i++)
        buf[i] *= 0.5 * (1.0 - cos(2.0 * M_PI * i / (n - 1)));
}

static void fft_radix2(double *re, double *im, int n, int inv)
{
    for (int i = 1, j = 0; i < n; i++) {
        int bit = n >> 1;
        for (; j & bit; bit >>= 1)
            j ^= bit;
        j ^= bit;
        if (i < j) {
            double tr = re[i]; re[i] = re[j]; re[j] = tr;
            double ti = im[i]; im[i] = im[j]; im[j] = ti;
        }
    }
    for (int len = 2; len <= n; len <<= 1) {
        double ang = 2.0 * M_PI / len * (inv ? -1 : 1);
        double wr = cos(ang), wi = sin(ang);
        for (int i = 0; i < n; i += len) {
            double cr = 1.0, ci = 0.0;
            for (int j = 0; j < len / 2; j++) {
                int a = i + j, b = a + len / 2;
                double tr = cr * re[b] - ci * im[b];
                double ti = cr * im[b] + ci * re[b];
                re[b] = re[a] - tr;  im[b] = im[a] - ti;
                re[a] += tr;         im[a] += ti;
                double ncr = cr * wr - ci * wi;
                double nci = cr * wi + ci * wr;
                cr = ncr; ci = nci;
            }
        }
    }
    if (inv)
        for (int i = 0; i < n; i++) { re[i] /= n; im[i] /= n; }
}

static void analyzer_add_window(Analyzer *a, const float *frame, int n)
{
    if (n < a->fft_size) return;

    double *buf = malloc(a->fft_size * sizeof(double));
    double *re  = malloc(a->fft_size * sizeof(double));
    double *im  = malloc(a->fft_size * sizeof(double));
    if (!buf || !re || !im) { free(buf); free(re); free(im); return; }

    for (int ch = 0; ch < a->channels; ch++) {
        for (int pos = 0; pos + a->fft_size <= n; pos += a->fft_size / OVERLAP_FACTOR) {
            for (int i = 0; i < a->fft_size; i++)
                buf[i] = frame[(pos + i) * a->channels + ch];
            apply_hann(buf, a->fft_size);
            memcpy(re, buf, a->fft_size * sizeof(double));
            memset(im, 0, a->fft_size * sizeof(double));
            fft_radix2(re, im, a->fft_size, 0);
            for (int i = 0; i < a->fft_size / 2; i++)
                a->power[i] += re[i]*re[i] + im[i]*im[i];
            a->count++;
        }
    }
    free(buf); free(re); free(im);
}

static void frame_to_ring(AVFrame *f, int nf, int channels, int fft_size,
                          float *ring, int *ring_pos, Analyzer *analyzer)
{
    int planar = av_sample_fmt_is_planar(f->format);
    int bps = av_get_bytes_per_sample(f->format);
    enum AVSampleFormat fmt = f->format;
    for (int i = 0; i < nf; i++) {
        for (int ch = 0; ch < channels; ch++) {
            const uint8_t *src;
            if (planar)
                src = f->extended_data[ch] + i * bps;
            else
                src = f->data[0] + (i * channels + ch) * bps;
            double val;
            switch (fmt) {
            case AV_SAMPLE_FMT_U8: case AV_SAMPLE_FMT_U8P:
                val = (*src - 128) / 128.0; break;
            case AV_SAMPLE_FMT_S16: case AV_SAMPLE_FMT_S16P:
                val = *(const int16_t *)src / 32768.0; break;
            case AV_SAMPLE_FMT_S32: case AV_SAMPLE_FMT_S32P:
                val = *(const int32_t *)src / 2147483648.0; break;
            case AV_SAMPLE_FMT_FLT: case AV_SAMPLE_FMT_FLTP:
                val = *(const float *)src; break;
            case AV_SAMPLE_FMT_DBL: case AV_SAMPLE_FMT_DBLP:
                val = *(const double *)src; break;
            default:
                val = 0.0; break;
            }
            ring[*ring_pos * channels + ch] = (float)val;
        }
        (*ring_pos)++;
        if (*ring_pos >= fft_size) {
            analyzer_add_window(analyzer, ring, *ring_pos);
            int slide = fft_size / 2;
            memmove(ring, ring + slide * channels,
                    (*ring_pos - slide) * channels * sizeof(float));
            *ring_pos -= slide;
        }
    }
}

static int detect_cutoff(const Analyzer *a, double threshold_db,
                         double sensitivity,
                         double *out_cutoff, double *out_steepness,
                         double *out_noise_db, double *out_roughness,
                         double *out_band_ratio)
{
    int n = a->fft_size / 2;
    int sr = a->sample_rate;

    double *mag = malloc(n * sizeof(double));
    if (!mag) return -1;

    double peak = 0.0;
    for (int i = 0; i < n; i++) {
        mag[i] = sqrt(a->power[i] / a->count);
        if (mag[i] > peak) peak = mag[i];
    }
    if (peak < 1e-12) { free(mag); return 0; }

    double threshold = peak * pow(10.0, threshold_db / 20.0);

    double cutoff_hz = 0;
    for (int i = n - 1; i >= 0; i--) {
        if (mag[i] >= threshold) { cutoff_hz = (double)i * sr / a->fft_size; break; }
    }
    *out_cutoff = cutoff_hz;

    /* Always compute transition bandwidth from -20 dB to -60 dB,
       independent of the user's threshold.  This keeps the steepness
       measurement consistent regardless of sensitivity setting. */
    double low_thresh_60 = peak * 0.001;
    double cutoff_60_hz = 0;
    int cutoff_60_bin = n - 1;
    for (int i = n - 1; i >= 0; i--) {
        if (mag[i] >= low_thresh_60) { cutoff_60_hz = (double)i * sr / a->fft_size; cutoff_60_bin = i; break; }
    }

    double high_thresh = peak * 0.1;
    double cutoff_high_hz = 0;
    int start = cutoff_60_bin > 0 ? cutoff_60_bin : n - 1;
    for (int i = start; i >= 0; i--) {
        if (mag[i] >= high_thresh) { cutoff_high_hz = (double)i * sr / a->fft_size; break; }
    }

    double transition_bw = (cutoff_60_hz > 0) ? cutoff_60_hz - cutoff_high_hz : 0;
    if (transition_bw < 0) transition_bw = 0;
    *out_steepness = transition_bw;

    double noise_sum = 0; int noise_count = 0;
    for (int i = n * 3 / 4; i < n; i++) {
        if (mag[i] > 0) { noise_sum += mag[i]; noise_count++; }
    }
    double noise_floor = (noise_count > 0) ? (noise_sum / noise_count) : 1e-12;
    *out_noise_db = 20.0 * log10(noise_floor / peak);

    double roughness = 0.0;
    double cutoff_idx = cutoff_hz * a->fft_size / sr;
    int lo = (int)(cutoff_idx * 0.60);
    int hi = (int)(cutoff_idx * 0.95);
    if (hi >= n) hi = n - 1;
    if (lo < 1) lo = 1;

    if (hi > lo) {
        double sum = 0;
        for (int i = lo; i <= hi; i++) sum += mag[i];
        double mean = sum / (hi - lo + 1);

        if (mean > 1e-12) {
            double var = 0;
            for (int i = lo; i <= hi; i++) {
                double dev = (mag[i] - mean) / mean;
                var += dev * dev;
            }
            roughness = sqrt(var / (hi - lo));
        }
    }
    if (roughness < 0.01) roughness = 0.01;
    *out_roughness = roughness;

    double energy_low = 0, energy_high = 0;
    int el_count = 0, eh_count = 0;
    for (int i = 0; i < n; i++) {
        double f = (double)i * sr / a->fft_size;
        if (f >= 12000 && f < 16000) { energy_low += mag[i]; el_count++; }
        if (f >= 16000 && f < 20000) { energy_high += mag[i]; eh_count++; }
    }
    double band_ratio = (el_count > 0 && eh_count > 0)
        ? (energy_high / eh_count) / (energy_low / el_count + 1e-12)
        : 0.5;
    *out_band_ratio = band_ratio;

    free(mag);

    double nyquist = sr / 2.0;
    double cutoff_ratio = cutoff_hz / nyquist;

    /* Scale detection thresholds by sensitivity (0.0 = least, 0.5 = default, 1.0 = most) */
    double bw_factor = 2.0 * (1.0 - sensitivity);
    if (bw_factor < 0.25) bw_factor = 0.25;
    double r1 = 0.40 * (1.0 + (0.5 - sensitivity) * 1.5);
    double r2 = 0.30 * (1.0 + (0.5 - sensitivity) * 1.5);
    double r3 = 0.20 * (1.0 + (0.5 - sensitivity) * 1.5);
    double b1 = 0.90 - (0.5 - sensitivity) * 0.10;
    double b2 = 0.85 - (0.5 - sensitivity) * 0.10;
    double bypass = 0.99 - (0.5 - sensitivity) * 0.02;

    int score = 0;

    if (cutoff_hz <= 0 || cutoff_ratio >= bypass) {
        if (roughness > r1) score = 1;
        else if (roughness > r2 && band_ratio < b1) score = 1;
        else if (roughness > r3 && band_ratio < b2) score = 1;
        return score;
    }

    double max_bw;
    if (cutoff_ratio < 0.50) {
        max_bw = 4000.0 * bw_factor;
    } else if (cutoff_ratio < 0.70) {
        max_bw = 3000.0 * bw_factor;
    } else if (cutoff_ratio < 0.80) {
        max_bw = 2000.0 * bw_factor;
    } else if (cutoff_ratio < 0.90) {
        max_bw = 1200.0 * bw_factor;
    } else {
        max_bw = 500.0 * bw_factor;
    }

    if (transition_bw < max_bw) score = 1;

    if (!score && cutoff_ratio > 0.80) {
        if (roughness > r1) score = 1;
        else if (roughness > r2 && band_ratio < b1) score = 1;
        else if (roughness > r3 && band_ratio < b2) score = 1;
    }

    return score;
}

/* ---- Terminal utilities ---- */

static int get_term_width(void)
{
    struct winsize ws;
    if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) == 0 && ws.ws_col > 0)
        return ws.ws_col;
    char *cols = getenv("COLUMNS");
    if (cols) {
        int n = atoi(cols);
        if (n > 0) return n;
    }
    return 80;
}

/* ---- Confidence / validity computation ---- */

static double compute_confidence(double cutoff_ratio, double steepness,
                                  double roughness, double band_ratio,
                                  int is_native_lossy)
{
    double conf = 0;
    int count = 0;

    if (is_native_lossy) {
        if (cutoff_ratio < 0.70) {
            double margin = (0.70 - cutoff_ratio) / 0.70;
            if (margin > 1) margin = 1;
            conf += 0.50 + 0.50 * margin;
            count++;
        } else if (cutoff_ratio < 0.80) {
            double margin = (0.80 - cutoff_ratio) / 0.80;
            if (margin > 1) margin = 1;
            conf += 0.40 + 0.60 * margin;
            count++;
        } else if (cutoff_ratio < 0.85) {
            double margin = (0.85 - cutoff_ratio) / 0.85;
            if (margin > 1) margin = 1;
            conf += 0.20 + 0.60 * margin;
            count++;
        } else {
            conf += 0.70;
            count++;
        }
    } else {
        if (cutoff_ratio < 0.50) {
            double margin = (0.50 - cutoff_ratio) / 0.50;
            if (margin > 1) margin = 1;
            double s_margin = (4000.0 - steepness) / 4000.0;
            if (s_margin > 1) s_margin = 1;
            if (s_margin < 0) s_margin = 0;
            conf += 0.50 + 0.50 * (margin * 0.5 + s_margin * 0.5);
            count++;
        } else if (cutoff_ratio < 0.70) {
            double r_margin = (0.70 - cutoff_ratio) / 0.70;
            if (r_margin > 1) r_margin = 1;
            double s_margin = (3000.0 - steepness) / 3000.0;
            if (s_margin > 1) s_margin = 1;
            if (s_margin < 0) s_margin = 0;
            conf += 0.30 + 0.70 * (r_margin * 0.4 + s_margin * 0.6);
            count++;
        } else if (cutoff_ratio < 0.80) {
            double r_margin = (0.80 - cutoff_ratio) / 0.80;
            if (r_margin > 1) r_margin = 1;
            double s_margin = (2000.0 - steepness) / 2000.0;
            if (s_margin > 1) s_margin = 1;
            if (s_margin < 0) s_margin = 0;
            conf += 0.20 + 0.80 * (r_margin * 0.4 + s_margin * 0.6);
            count++;
        } else if (cutoff_ratio < 0.90) {
            double r_margin = (0.90 - cutoff_ratio) / 0.90;
            if (r_margin > 1) r_margin = 1;
            double s_margin = (1200.0 - steepness) / 1200.0;
            if (s_margin > 1) s_margin = 1;
            if (s_margin < 0) s_margin = 0;
            conf += 0.10 + 0.90 * (r_margin * 0.4 + s_margin * 0.6);
            count++;
        } else {
            double s_margin = (500.0 - steepness) / 500.0;
            if (s_margin > 1) s_margin = 1;
            if (s_margin < 0) s_margin = 0;
            conf += 0.20 + 0.80 * s_margin;
            count++;
        }

        if (cutoff_ratio > 0.80) {
            if (roughness > 0.40) {
                double margin = (roughness - 0.40) / 0.40;
                if (margin > 1) margin = 1;
                conf += 0.40 + 0.60 * margin;
                count++;
            } else if (roughness > 0.30 && band_ratio < 0.90) {
                double r_margin = (roughness - 0.30) / 0.10;
                if (r_margin > 1) r_margin = 1;
                double b_margin = (0.90 - band_ratio) / 0.90;
                if (b_margin > 1) b_margin = 1;
                conf += 0.20 + 0.80 * (r_margin * 0.5 + b_margin * 0.5);
                count++;
            } else if (roughness > 0.20 && band_ratio < 0.85) {
                double r_margin = (roughness - 0.20) / 0.10;
                if (r_margin > 1) r_margin = 1;
                double b_margin = (0.85 - band_ratio) / 0.85;
                if (b_margin > 1) b_margin = 1;
                conf += 0.10 + 0.90 * (r_margin * 0.5 + b_margin * 0.5);
                count++;
            }
        }
    }

    if (count == 0) return 0;
    double result = conf / count * 100.0;
    if (result < 0) result = 0;
    if (result > 100) result = 100;
    return result;
}

/* ---- Visual spectrum renderer ---- */

static void repeat_char(char c, int n)
{
    for (int i = 0; i < n; i++) putchar(c);
}

static void repeat_str(const char *s, int n)
{
    for (int i = 0; i < n; i++) printf("%s", s);
}

static void draw_hline(int width)
{
    printf(ANSI_BLUE "│" ANSI_RESET);
    printf(ANSI_BLUE); repeat_str("─", width); printf(ANSI_RESET);
    printf(ANSI_BLUE "│" ANSI_RESET);
    printf("\n");
}

static void freq_label_row(int chart_w, double nyquist)
{
    static const double freqs[] = {20, 50, 100, 200, 500, 1000, 2000, 5000, 10000, 15000, 20000};
    static const char *labels[] = {"20", "50", "100", "200", "500", "1k", "2k", "5k", "10k", "15k", "20k"};
    int n = sizeof(freqs) / sizeof(freqs[0]);

    int pos[11], n_valid = 0;
    for (int i = 0; i < n; i++) {
        if (freqs[i] < nyquist) {
            pos[n_valid] = (int)(freqs[i] / nyquist * chart_w);
            if (pos[n_valid] >= chart_w) pos[n_valid] = chart_w - 1;
            if (pos[n_valid] < 0) pos[n_valid] = 0;
            n_valid++;
        }
    }

    int min_gap = 5;
    int keep[11], n_keep = 0;
    int last_pos = -100;
    for (int i = 0; i < n_valid; i++) {
        if (pos[i] - last_pos >= min_gap) {
            keep[n_keep] = i;
            last_pos = pos[i];
            n_keep++;
        }
    }

    printf(ANSI_BLUE "│" ANSI_RESET);
    int p = 0;
    for (int i = 0; i < chart_w; i++) {
        if (p < n_keep && i == pos[keep[p]]) {
            printf(ANSI_BLUE "┬" ANSI_RESET);
            p++;
        } else {
            putchar(' ');
        }
    }
    printf(ANSI_BLUE "│" ANSI_RESET);
    printf("\n");

    printf(ANSI_BLUE "│" ANSI_RESET);
    p = 0;
    for (int i = 0; i < chart_w; i++) {
        if (p < n_keep && i == pos[keep[p]]) {
            const char *label = labels[keep[p]];
            int llen = strlen(label);
            printf(ANSI_BOLD "%s" ANSI_RESET, label);
            i += llen - 1;
            p++;
        } else {
            putchar(' ');
        }
    }
    printf(ANSI_BLUE "│" ANSI_RESET);
    printf("\n");
}

static void render_visual_spectrum(
    const Analyzer *a,
    double cutoff_hz, double steepness, double noise_db,
    double roughness, double band_ratio,
    int is_transcode, int is_native_lossy, int upscaled,
    double peak_db, double threshold_db,
    const char *filename, const char *fmt_name,
    int sample_rate, int channels, int analyzer_count,
    int fft_size, int64_t bitrate)
{
    (void)threshold_db;

    int term_w = get_term_width();
    if (term_w < 60) term_w = 60;

    int n_bins = fft_size / 2;
    double nyquist = sample_rate / 2.0;

    int label_w = 7;
    int chart_w = term_w - label_w - 2;
    if (chart_w < 20) chart_w = 20;

    double *spec = malloc(n_bins * sizeof(double));
    if (!spec) { fprintf(stderr, "Error: malloc failed\n"); return; }

    double peak = 0;
    for (int i = 0; i < n_bins; i++) {
        double m = sqrt(a->power[i] / a->count);
        if (m > peak) peak = m;
    }
    if (peak < 1e-12) peak = 1e-12;

    for (int i = 0; i < n_bins; i++) {
        double m = sqrt(a->power[i] / a->count);
        spec[i] = 20.0 * log10(m / peak);
    }

    double *col_max = calloc(chart_w, sizeof(double));
    if (!col_max) { free(spec); return; }
    for (int c = 0; c < chart_w; c++) col_max[c] = -200.0;

    for (int i = 0; i < n_bins; i++) {
        int c = (i * chart_w) / n_bins;
        if (c >= chart_w) c = chart_w - 1;
        if (spec[i] > col_max[c]) col_max[c] = spec[i];
    }

    int cutoff_col = (cutoff_hz > 0 && nyquist > 0)
        ? (int)(cutoff_hz / nyquist * chart_w) : chart_w - 1;
    if (cutoff_col < 0) cutoff_col = 0;
    if (cutoff_col >= chart_w) cutoff_col = chart_w - 1;

    double db_min = -100.0;
    double db_max = 4.0;
    int n_rows = 8;
    double db_step = (db_max - db_min) / n_rows;

    /* ============================ */
    /*         TOP BORDER           */
    /* ============================ */
    printf(ANSI_BLUE "╭" ANSI_RESET);
    printf(ANSI_BLUE); repeat_str("─", chart_w + label_w); printf(ANSI_RESET);
    printf(ANSI_BLUE "╮" ANSI_RESET "\n");

    /* --- Title bar --- */
    char title[256];
    const char *short_name = strrchr(filename, '/');
    short_name = short_name ? short_name + 1 : filename;
    int info_len = snprintf(title, sizeof(title), "  %s  |  %s  |  %d Hz  |  %d ch",
                            short_name, fmt_name, sample_rate, channels);
    int total_w = term_w - 2;
    if (info_len > total_w) {
        char truncated[256];
        snprintf(truncated, sizeof(truncated), "  %s  |  %d Hz  |  %d ch",
                 short_name, sample_rate, channels);
        if ((int)strlen(truncated) > total_w) {
            snprintf(truncated, sizeof(truncated), "  %s  |  %d ch", short_name, channels);
            if ((int)strlen(truncated) > total_w) {
                snprintf(truncated, sizeof(truncated), "  %s", short_name);
                if ((int)strlen(truncated) > total_w) {
                    truncated[total_w] = '\0';
                }
            }
        }
        printf(ANSI_BLUE "│" ANSI_RESET);
        printf(ANSI_BOLD ANSI_CYAN "%s" ANSI_RESET, truncated);
        repeat_char(' ', total_w - (int)strlen(truncated));
        printf(ANSI_BLUE "│" ANSI_RESET "\n");
    } else {
        printf(ANSI_BLUE "│" ANSI_RESET);
        printf(ANSI_BOLD ANSI_CYAN "%s" ANSI_RESET, title);
        repeat_char(' ', total_w - info_len);
        printf(ANSI_BLUE "│" ANSI_RESET "\n");
    }

    draw_hline(chart_w + label_w);

    /* ============================ */
    /*        SPECTRUM CHART        */
    /* ============================ */
    for (int row = 0; row < n_rows; row++) {
        double db_val = db_max - row * db_step;
        printf(ANSI_BLUE "│" ANSI_RESET);
        printf(ANSI_DIM "%6.0f " ANSI_RESET, db_val);

        for (int c = 0; c < chart_w; c++) {
            double v = col_max[c];
            double thresh_high = db_val;
            double thresh_mid  = db_val - db_step;
            double thresh_low  = db_val - 2 * db_step;

            if (v >= thresh_high) {
                printf("█");
            } else if (v >= thresh_mid) {
                printf("▓");
            } else if (v >= thresh_low) {
                printf("▒");
            } else {
                printf("░");
            }
        }
        printf(ANSI_BLUE "│" ANSI_RESET "\n");
    }

    /* --- Cutoff arrow row --- */
    printf(ANSI_BLUE "│" ANSI_RESET);
    repeat_char(' ', label_w);
    for (int c = 0; c < chart_w; c++) {
        if (c == cutoff_col) {
            printf(ANSI_YELLOW "┬" ANSI_RESET);
        } else {
            putchar(' ');
        }
    }
    printf(ANSI_BLUE "│" ANSI_RESET "\n");

    /* --- Cutoff label --- */
    char cutoff_label[64];
    if (cutoff_hz >= 1000)
        snprintf(cutoff_label, sizeof(cutoff_label), "Cutoff %.1fkHz (%.0f%% Nyq)",
                 cutoff_hz / 1000.0, 100.0 * cutoff_hz / nyquist);
    else
        snprintf(cutoff_label, sizeof(cutoff_label), "Cutoff %.0fHz (%.0f%% Nyq)",
                 cutoff_hz, 100.0 * cutoff_hz / nyquist);

    int clen = strlen(cutoff_label);
    int label_start = cutoff_col - clen / 2;
    if (label_start < 0) label_start = 0;
    if (label_start + clen > chart_w) label_start = chart_w - clen;

    printf(ANSI_BLUE "│" ANSI_RESET);
    repeat_char(' ', label_w);
    repeat_char(' ', label_start);
    printf(ANSI_YELLOW ANSI_BOLD "%s" ANSI_RESET, cutoff_label);
    int remain = chart_w - label_start - clen;
    if (remain > 0) repeat_char(' ', remain);
    printf(ANSI_BLUE "│" ANSI_RESET "\n");

    /* --- Tick marks --- */
    freq_label_row(chart_w, nyquist);

    /* ============================ */
    /*      METRICS SECTION        */
    /* ============================ */
    draw_hline(chart_w + label_w);

    char peak_dbfs_str[32];
    snprintf(peak_dbfs_str, sizeof(peak_dbfs_str), "%.1f", 20.0 * log10(peak));

    printf(ANSI_BLUE "│" ANSI_RESET "  " ANSI_BOLD "Peak:" ANSI_RESET " %7s dBFS  " ANSI_BLUE "│" ANSI_RESET "  " ANSI_BOLD "Windows:" ANSI_RESET " %d  " ANSI_BLUE "│" ANSI_RESET "  " ANSI_BOLD "FFT:" ANSI_RESET " %d",
           peak_dbfs_str, analyzer_count, fft_size);
    int used_metrics = 30 + 14 + 10 + 14;
    repeat_char(' ', term_w - 2 - used_metrics);
    printf(ANSI_BLUE "│" ANSI_RESET "\n");

    draw_hline(chart_w + label_w);

    printf(ANSI_BLUE "│" ANSI_RESET "  " ANSI_BOLD "Cutoff:" ANSI_RESET " %7.0f Hz  (%5.1f%%)  " ANSI_BLUE "│" ANSI_RESET "  " ANSI_BOLD "Steepness:" ANSI_RESET " %6.0f Hz  " ANSI_BLUE "│" ANSI_RESET "  " ANSI_BOLD "Noise:" ANSI_RESET " %6.1f dB",
           cutoff_hz, 100.0 * cutoff_hz / nyquist, steepness, noise_db);
    repeat_char(' ', term_w - 2 - 62);
    printf(ANSI_BLUE "│" ANSI_RESET "\n");

    printf(ANSI_BLUE "│" ANSI_RESET "  " ANSI_BOLD "Roughness:" ANSI_RESET " %6.3f  " ANSI_BLUE "│" ANSI_RESET "  " ANSI_BOLD "Band ratio:" ANSI_RESET " %6.3f",
           roughness, band_ratio);
    repeat_char(' ', term_w - 2 - 36);
    printf(ANSI_BLUE "│" ANSI_RESET "\n");

    /* ============================ */
    /*    DECISION / VALIDITY       */
    /* ============================ */
    draw_hline(chart_w + label_w);

    double cutoff_ratio = cutoff_hz / nyquist;
    double confidence = compute_confidence(
        cutoff_ratio, steepness, roughness, band_ratio, is_native_lossy);

    printf(ANSI_BLUE "│" ANSI_RESET "  " ANSI_BOLD "Decision:" ANSI_RESET " ");
    if (peak_db < -90.0) {
        printf(ANSI_RED "SILENT" ANSI_RESET " (no detectable audio content)");
    } else if (is_native_lossy) {
        if (upscaled)
            printf(ANSI_YELLOW "UPSCALED" ANSI_RESET " (re-encoded from lower bitrate)");
        else
            printf(ANSI_GREEN "NATIVE" ANSI_RESET " (single encode at this bitrate)");
    } else {
        if (is_transcode)
            printf(ANSI_YELLOW "TRANSCODE" ANSI_RESET " (lossy \xe2\x86\x92 lossless re-encode)");
        else
            printf(ANSI_GREEN "GENUINE" ANSI_RESET " (likely native lossless)");
    }
    int dlen = (int)strlen("  Decision: ") + 50;
    repeat_char(' ', term_w - 2 - dlen);
    printf(ANSI_BLUE "│" ANSI_RESET "\n");

    /* Validity bar */
    int bar_w = 20;
    int filled = (int)(confidence / 100.0 * bar_w);
    if (filled < 0) filled = 0;
    if (filled > bar_w) filled = bar_w;

    const char *conf_label;
    if (confidence >= 85) conf_label = "Very strong evidence";
    else if (confidence >= 70) conf_label = "Strong evidence";
    else if (confidence >= 50) conf_label = "Moderate evidence";
    else if (confidence >= 30) conf_label = "Weak evidence";
    else conf_label = "Borderline / inconclusive";

    printf(ANSI_BLUE "│" ANSI_RESET "  " ANSI_BOLD "Validity:" ANSI_RESET " ");
    for (int i = 0; i < bar_w; i++) {
        if (i < filled) printf(ANSI_GREEN "█" ANSI_RESET);
        else printf(ANSI_DIM "░" ANSI_RESET);
    }
    printf(ANSI_BOLD " %3.0f%%" ANSI_RESET, confidence);
    printf("  \xe2\x80\x94 %s", conf_label);
    int vlen = 12 + bar_w + 5 + 2 + (int)strlen(conf_label);
    repeat_char(' ', term_w - 2 - vlen);
    printf(ANSI_BLUE "│" ANSI_RESET "\n");

    printf(ANSI_BLUE "│" ANSI_RESET);
    repeat_char(' ', term_w - 2);
    printf(ANSI_BLUE "│" ANSI_RESET "\n");

    /* --- Factor breakdown --- */
    printf(ANSI_BLUE "│" ANSI_RESET "  " ANSI_BOLD "Factors:" ANSI_RESET);
    repeat_char(' ', term_w - 12);
    printf(ANSI_BLUE "│" ANSI_RESET "\n");

    if (is_native_lossy) {
        if (upscaled) {
            char line[128];
            snprintf(line, sizeof(line),
                     "    cutoff_ratio=%.3f < expected for bitrate (%lld kbps)",
                     cutoff_ratio, (long long)(bitrate / 1000));
            printf(ANSI_BLUE "│" ANSI_RESET "  %s  " ANSI_GREEN "✓" ANSI_RESET, line);
            int remain = term_w - 4 - (int)strlen(line) - 2;
            if (remain > 0) repeat_char(' ', remain);
            printf(ANSI_BLUE "│" ANSI_RESET "\n");

            const char *src_hint = "";
            if (cutoff_ratio < 0.70) src_hint = "≤ 64 kbps source";
            else if (cutoff_ratio < 0.80) src_hint = "96–128 kbps source";
            else if (cutoff_ratio < 0.88) src_hint = "128–192 kbps source";
            printf(ANSI_BLUE "│" ANSI_RESET "    → " ANSI_BOLD "Suggest %s" ANSI_RESET, src_hint);
            repeat_char(' ', term_w - 4 - (int)strlen(src_hint) - 14);
            printf(ANSI_BLUE "│" ANSI_RESET "\n");
        } else {
            printf(ANSI_BLUE "│" ANSI_RESET "    cutoff_ratio=%.3f within expected range for this bitrate  " ANSI_GREEN "✓" ANSI_RESET, cutoff_ratio);
            repeat_char(' ', term_w - 2 - 68);
            printf(ANSI_BLUE "│" ANSI_RESET "\n");
        }
    } else {
        double max_bw_display;
        if (cutoff_ratio < 0.50) {
            max_bw_display = 4000.0;
        } else if (cutoff_ratio < 0.70) {
            max_bw_display = 3000.0;
        } else if (cutoff_ratio < 0.80) {
            max_bw_display = 2000.0;
        } else if (cutoff_ratio < 0.90) {
            max_bw_display = 1200.0;
        } else {
            max_bw_display = 500.0;
        }

        int primary_hit = (cutoff_ratio >= 0.99) ? 0 : (steepness < max_bw_display);
        int secondary_applies = (cutoff_ratio > 0.80);

        if (cutoff_ratio >= 0.99) {
            printf(ANSI_BLUE "│" ANSI_RESET "    ① cutoff_ratio=%.3f ≥ 0.99  " ANSI_RED "✗" ANSI_RESET "  (full spectrum, no cutoff)", cutoff_ratio);
            repeat_char(' ', term_w - 2 - 62);
            printf(ANSI_BLUE "│" ANSI_RESET "\n");
        } else {
            char bw_label[64];
            snprintf(bw_label, sizeof(bw_label), "transition_bw=%.0fHz < %.0fHz threshold",
                     steepness, max_bw_display);

            if (primary_hit) {
                printf(ANSI_BLUE "│" ANSI_RESET "    ① cutoff_ratio=%.3f, %s  " ANSI_GREEN "✓" ANSI_RESET,
                       cutoff_ratio, bw_label);
                repeat_char(' ', term_w - 2 - (int)strlen(bw_label) - 24);
                printf(ANSI_BLUE "│" ANSI_RESET "\n");
            } else {
                printf(ANSI_BLUE "│" ANSI_RESET "    ① cutoff_ratio=%.3f, transition_bw=%.0fHz ≥ %.0fHz threshold  " ANSI_RED "✗" ANSI_RESET,
                       cutoff_ratio, steepness, max_bw_display);
                repeat_char(' ', term_w - 2 - 71);
                printf(ANSI_BLUE "│" ANSI_RESET "\n");
            }
        }

        if (primary_hit) {
            printf(ANSI_BLUE "│" ANSI_RESET "    → " ANSI_YELLOW "Transition bandwidth indicates transcode" ANSI_RESET);
            repeat_char(' ', term_w - 2 - 44);
            printf(ANSI_BLUE "│" ANSI_RESET "\n");
        }

        if (secondary_applies) {
            int sec_hit = 0;
            if (roughness > 0.40) {
                printf(ANSI_BLUE "│" ANSI_RESET "    ② roughness=%.3f > 0.40  " ANSI_GREEN "✓" ANSI_RESET "  (high roughness → transcode)", roughness);
                repeat_char(' ', term_w - 2 - 60);
                printf(ANSI_BLUE "│" ANSI_RESET "\n");
                sec_hit = 1;
            } else if (roughness > 0.30 && band_ratio < 0.90) {
                printf(ANSI_BLUE "│" ANSI_RESET "    ② roughness=%.3f > 0.30  " ANSI_GREEN "✓" ANSI_RESET "  band_ratio=%.3f < 0.90  " ANSI_GREEN "✓" ANSI_RESET,
                       roughness, band_ratio);
                repeat_char(' ', term_w - 2 - 62);
                printf(ANSI_BLUE "│" ANSI_RESET "\n");
                sec_hit = 1;
            } else if (roughness > 0.20 && band_ratio < 0.85) {
                printf(ANSI_BLUE "│" ANSI_RESET "    ② roughness=%.3f > 0.20  " ANSI_GREEN "✓" ANSI_RESET "  band_ratio=%.3f < 0.85  " ANSI_GREEN "✓" ANSI_RESET,
                       roughness, band_ratio);
                repeat_char(' ', term_w - 2 - 62);
                printf(ANSI_BLUE "│" ANSI_RESET "\n");
                sec_hit = 1;
            }

            if (sec_hit) {
                printf(ANSI_BLUE "│" ANSI_RESET "    → " ANSI_YELLOW "Secondary criteria triggered: transcode confirmed" ANSI_RESET);
                repeat_char(' ', term_w - 2 - 52);
                printf(ANSI_BLUE "│" ANSI_RESET "\n");
            } else if (!primary_hit) {
                printf(ANSI_BLUE "│" ANSI_RESET "    ② Secondary: roughness=%.3f, band_ratio=%.3f  " ANSI_RED "✗" ANSI_RESET,
                       roughness, band_ratio);
                repeat_char(' ', term_w - 2 - 56);
                printf(ANSI_BLUE "│" ANSI_RESET "\n");
                printf(ANSI_BLUE "│" ANSI_RESET "    → " ANSI_GREEN "No transcode criteria met: genuine lossless" ANSI_RESET);
                repeat_char(' ', term_w - 2 - 46);
                printf(ANSI_BLUE "│" ANSI_RESET "\n");
            }
        } else if (!primary_hit) {
            printf(ANSI_BLUE "│" ANSI_RESET "    → " ANSI_GREEN "No transcode criteria met: genuine lossless" ANSI_RESET);
            repeat_char(' ', term_w - 2 - 46);
            printf(ANSI_BLUE "│" ANSI_RESET "\n");
        }
    }

    /* ============================ */
    /*        BOTTOM BORDER         */
    /* ============================ */
    printf(ANSI_BLUE "╰" ANSI_RESET);
    printf(ANSI_BLUE); repeat_str("─", chart_w + label_w); printf(ANSI_RESET);
    printf(ANSI_BLUE "╯" ANSI_RESET "\n");

    free(spec);
    free(col_max);
}

static int vis_len(const char *s)
{
    int len = 0;
    while (*s) {
        unsigned char c = (unsigned char)*s;
        if (c == '\033') {
            while (*s && *s != 'm') s++;
            if (*s) s++;
        } else if ((c & 0xC0) == 0x80) {
            s++;
        } else {
            len++;
            s++;
        }
    }
    return len;
}

static void pn(const char *s)    { printf("%s", s); }
static void pl(const char *s, int w)
{
    int sl = vis_len(s);
    printf(ANSI_BLUE "│" ANSI_RESET "  %s", s);
    int pad = w - 4 - sl;
    if (pad > 0) repeat_char(' ', pad);
    printf(ANSI_BLUE "│" ANSI_RESET "\n");
}

static void print_help(const char *prog)
{
    int tw = get_term_width();
    if (tw < 60) tw = 80;

    pn(ANSI_BLUE "╭"); repeat_str("─", tw - 2); pn(ANSI_BLUE "╮" ANSI_RESET "\n");

    pl("", tw);
    {
        char buf[256];
        snprintf(buf, sizeof(buf), ANSI_BOLD ANSI_CYAN "tcd" ANSI_RESET
                 " \xe2\x80\x94 Transcode Detector   "
                 "Psychoacoustic audio authenticity analysis");
        int v = vis_len(buf);
        printf(ANSI_BLUE "│" ANSI_RESET "  %s", buf);
        int pad = tw - 4 - v;
        if (pad > 0) repeat_char(' ', pad);
        printf(ANSI_BLUE "│" ANSI_RESET "\n");
    }
    pl("", tw);

    pl("Analyze audio files to detect transcodes (lossy \xe2\x86\x92 lossless", tw);
    pl("re-encodes) by measuring spectral cutoffs and artifacts.", tw);
    pl("", tw);
    {
        char buf[256];
        snprintf(buf, sizeof(buf),
                 ANSI_BOLD "Usage:" ANSI_RESET "  %s [options] [<audio-file> ...]", prog);
        int v = vis_len(buf);
        printf(ANSI_BLUE "│" ANSI_RESET "  %s", buf);
        int pad = tw - 4 - v;
        if (pad > 0) repeat_char(' ', pad);
        printf(ANSI_BLUE "│" ANSI_RESET "\n");
    }
    pl("", tw);

    pn(ANSI_BLUE "│" ANSI_RESET "  " ANSI_BOLD "Options:" ANSI_RESET);
    repeat_char(' ', tw - 12);
    pn(ANSI_BLUE "│" ANSI_RESET "\n");

#define OPT(fmt, desc) do { \
    printf(ANSI_BLUE "│" ANSI_RESET "    " ANSI_GREEN fmt ANSI_RESET "  %s", desc); \
    int v = 1 + 4 + (int)strlen(fmt) + 2 + vis_len(desc); \
    int pad = tw - 1 - v; \
    if (pad > 0) repeat_char(' ', pad); \
    printf(ANSI_BLUE "│" ANSI_RESET "\n"); \
} while (0)

    {
        char buf[80];
        snprintf(buf, sizeof(buf), "Detection sensitivity 1-99  [" ANSI_CYAN "%d" ANSI_RESET "]", THRESHOLD_DEFAULT);
        OPT("-t, --threshold PCT", buf);
    }
    {
        char buf[80];
        snprintf(buf, sizeof(buf), ANSI_DIM "  Lower = fewer, higher = more" ANSI_RESET);
        int v = 1 + 4 + vis_len(buf);
        printf(ANSI_BLUE "│" ANSI_RESET "    %s", buf);
        int pad = tw - 1 - v;
        if (pad > 0) repeat_char(' ', pad);
        printf(ANSI_BLUE "│" ANSI_RESET "\n");
    }
    {
        char buf[80];
        snprintf(buf, sizeof(buf), "FFT size, power of 2       [" ANSI_CYAN "%d" ANSI_RESET "]", FFT_SIZE_DEFAULT);
        OPT("-f, --fft-size N",   buf);
    }
    {
        char buf[80];
        snprintf(buf, sizeof(buf), "Seconds to analyze         [" ANSI_CYAN "%d" ANSI_RESET "]", MAX_ANALYSIS_SECS);
        OPT("-d, --duration SEC", buf);
    }
    OPT("-r, --recursive",    "Recurse into subdirectories");
    OPT("-F, --full",         "Analyze entire file (no duration limit)");
    OPT("-v, --verbose",      "Verbose output with decision log");
    OPT("-s, --visual",       "Graphical spectrum TUI visualization");
    OPT("-V",                 "Alias for " ANSI_GREEN "-s" ANSI_RESET);
    OPT("-a, --auto-remove",  "Automatically delete detected transcodes");
    OPT("-h, --help",         "Show this help screen");

#undef OPT

    pn(ANSI_BLUE "╰"); repeat_str("─", tw - 2); pn(ANSI_BLUE "╯" ANSI_RESET "\n");
}

static void maybe_remove(const char *filename, int peak_db_neg90,
                          int is_native_lossy, int upscaled, int is_transcode)
{
    int should_remove = 0;
    if (peak_db_neg90) {
        should_remove = 1;
    } else if (is_native_lossy) {
        should_remove = upscaled;
    } else {
        should_remove = is_transcode > 0;
    }
    if (should_remove) {
        int tw = get_term_width();
        int elen = 15 + (int)strlen(filename);
        printf(ANSI_YELLOW "===> " ANSI_RESET ANSI_BRIGHT_RED ANSI_BOLD "Removing:" ANSI_RESET ANSI_BRIGHT_RED " %s", filename);
        if (elen < tw) repeat_char(' ', tw - elen);
        printf(ANSI_RESET "\n");
        if (remove(filename) != 0)
            fprintf(stderr, "Error: could not remove '%s'.\n", filename);
    }
}

/* ---- Options bundle ---- */

typedef struct {
    double threshold_db;
    double sensitivity;
    int    fft_size;
    int    max_secs;
    int    verbose;
    int    dump_spectrum;
    int    visual;
    int    auto_remove;
    int    recursive;
    int    full;
} Options;

/* ---- Audio extension check ---- */

static int is_audio_ext(const char *path)
{
    const char *ext = strrchr(path, '.');
    if (!ext) return 0;
    ext++;
    static const char *exts[] = {
        "mp3", "flac", "wav", "aiff", "aif", "ogg", "opus",
        "m4a", "wma", "ac3", "eac3", "aac", "alac", "wv",
        "mp2", "mp1", "ape", "dsf", "dff", NULL
    };
    for (const char **p = exts; *p; p++)
        if (strcasecmp(ext, *p) == 0) return 1;
    return 0;
}

/* ---- Single-file processor ---- */

static int process_file(const char *filename, const Options *opts)
{
    AVFormatContext *fmt_ctx = NULL;
    if (avformat_open_input(&fmt_ctx, filename, NULL, NULL) < 0) {
        fprintf(stderr, "Error: could not open '%s'.\n", filename);
        return 1;
    }

    if (avformat_find_stream_info(fmt_ctx, NULL) < 0) {
        fprintf(stderr, "Error: could not find stream info.\n");
        avformat_close_input(&fmt_ctx);
        return 1;
    }

    const AVCodec *decoder = NULL;
    int stream_idx = av_find_best_stream(fmt_ctx, AVMEDIA_TYPE_AUDIO, -1, -1, &decoder, 0);
    if (stream_idx < 0) {
        fprintf(stderr, "Error: no audio stream found.\n");
        avformat_close_input(&fmt_ctx);
        return 1;
    }

    AVStream *stream = fmt_ctx->streams[stream_idx];
    AVCodecContext *codec_ctx = avcodec_alloc_context3(decoder);
    if (!codec_ctx) {
        fprintf(stderr, "Error: could not allocate codec context.\n");
        avformat_close_input(&fmt_ctx);
        return 1;
    }

    if (avcodec_parameters_to_context(codec_ctx, stream->codecpar) < 0) {
        fprintf(stderr, "Error: could not copy codec parameters.\n");
        avcodec_free_context(&codec_ctx);
        avformat_close_input(&fmt_ctx);
        return 1;
    }

    if (avcodec_open2(codec_ctx, decoder, NULL) < 0) {
        fprintf(stderr, "Error: could not open decoder.\n");
        avcodec_free_context(&codec_ctx);
        avformat_close_input(&fmt_ctx);
        return 1;
    }

    int sample_rate = codec_ctx->sample_rate;
    int channels    = codec_ctx->ch_layout.nb_channels;
    int64_t bitrate = codec_ctx->bit_rate;
    int64_t duration_av = fmt_ctx->duration;
    const char *fmt_name = fmt_ctx->iformat ? fmt_ctx->iformat->name : "?";
    const char *codec_name = decoder->name;

    int is_native_lossy = 0;
    const char *lossy_codecs[] = {
        "mp3", "mp3float", "aac", "libfdk_aac", "vorbis", "opus",
        "wmav1", "wmav2", "wmapro", "libvorbis", "ac3", "eac3",
        "mp2", "mp1", NULL
    };
    for (const char **p = lossy_codecs; *p; p++) {
        if (strcmp(codec_name, *p) == 0) { is_native_lossy = 1; break; }
    }

    if (opts->verbose) {
        fprintf(stderr, "Format:   %s\n", fmt_name);
        fprintf(stderr, "Channels: %d, Sample rate: %d Hz\n",
                channels, sample_rate);
        fprintf(stderr, "Bitrate:  %lld bps\n", (long long)bitrate);
        fprintf(stderr, "Decoder:  %s (%s)\n", decoder->name, decoder->long_name ? decoder->long_name : "");
        if (duration_av != AV_NOPTS_VALUE)
            fprintf(stderr, "Duration: %lld seconds\n",
                    (long long)(duration_av / AV_TIME_BASE));
    }

    Analyzer analyzer;
    analyzer_init(&analyzer, sample_rate, channels, opts->fft_size);

    AVPacket *pkt = av_packet_alloc();
    AVFrame  *frame = av_frame_alloc();
    if (!pkt || !frame) {
        fprintf(stderr, "Error: could not allocate packet/frame.\n");
        av_packet_free(&pkt);
        av_frame_free(&frame);
        analyzer_free(&analyzer);
        avcodec_free_context(&codec_ctx);
        avformat_close_input(&fmt_ctx);
        return 1;
    }

    int max_frames = opts->full ? INT_MAX : sample_rate * opts->max_secs;
    int total_frames = 0;

    float *ring = calloc(opts->fft_size * channels, sizeof(float));
    int ring_pos = 0;

    while (total_frames < max_frames && av_read_frame(fmt_ctx, pkt) == 0) {
        if (pkt->stream_index != stream_idx) {
            av_packet_unref(pkt);
            continue;
        }
        if (avcodec_send_packet(codec_ctx, pkt) < 0) {
            av_packet_unref(pkt);
            continue;
        }
        av_packet_unref(pkt);

        while (total_frames < max_frames) {
            int ret = avcodec_receive_frame(codec_ctx, frame);
            if (ret == AVERROR(EAGAIN))
                break;
            if (ret == AVERROR_EOF)
                break;
            if (ret < 0)
                break;
            int nframes = frame->nb_samples;
            if (nframes > max_frames - total_frames)
                nframes = max_frames - total_frames;
            if (nframes <= 0) break;
            frame_to_ring(frame, nframes, channels, opts->fft_size, ring, &ring_pos, &analyzer);
            total_frames += nframes;
        }
    }

    avcodec_send_packet(codec_ctx, NULL);
    while (total_frames < max_frames) {
        int ret = avcodec_receive_frame(codec_ctx, frame);
        if (ret == AVERROR_EOF || ret < 0)
            break;
        int nframes = frame->nb_samples;
        if (nframes > max_frames - total_frames)
            nframes = max_frames - total_frames;
        if (nframes <= 0) break;
        frame_to_ring(frame, nframes, channels, opts->fft_size, ring, &ring_pos, &analyzer);
        total_frames += nframes;
    }

    if (ring_pos >= opts->fft_size)
        analyzer_add_window(&analyzer, ring, ring_pos);

    free(ring);

    av_packet_free(&pkt);
    av_frame_free(&frame);
    avcodec_free_context(&codec_ctx);
    avformat_close_input(&fmt_ctx);

    if (analyzer.count == 0) {
        if (total_frames > 0)
            fprintf(stderr, "Error: file too short for analysis (%d samples, need %d).\n"
                    "       Use -f to set a smaller FFT size.\n",
                    total_frames, opts->fft_size);
        else
            fprintf(stderr, "Error: no audio data decoded from '%s'.\n", filename);
        analyzer_free(&analyzer);
        return 1;
    }

    double cutoff_hz = 0, steepness = 0, noise_db = 0;
    double roughness = 0, band_ratio = 0;
    int is_transcode = detect_cutoff(&analyzer, opts->threshold_db,
                                     opts->sensitivity,
                                     &cutoff_hz, &steepness, &noise_db,
                                     &roughness, &band_ratio);
    double nyquist = sample_rate / 2.0;

    double peak_mag = 0;
    for (int i = 0; i < opts->fft_size / 2; i++) {
        double m = sqrt(analyzer.power[i] / analyzer.count);
        if (m > peak_mag) peak_mag = m;
    }
    double peak_db = (peak_mag > 1e-12) ? 20.0 * log10(peak_mag) : -200.0;

    /* ---- Visual output ---- */
    if (opts->visual) {
        printf("\n");
        if (peak_db < -90.0) {
            printf(ANSI_RED "╭────────────────────────────────────────╮\n" ANSI_RESET);
            printf(ANSI_RED "│" ANSI_RESET "  " ANSI_BOLD ANSI_RED "SILENT" ANSI_RESET " \xe2\x80\x94 no detectable audio content  " ANSI_RED "│\n" ANSI_RESET);
            printf(ANSI_RED "╰────────────────────────────────────────╯\n" ANSI_RESET);
            analyzer_free(&analyzer);
            if (opts->auto_remove) maybe_remove(filename, 1, 0, 0, 0);
            return 2;
        }

        double cutoff_ratio = cutoff_hz / nyquist;
        int upscaled = 0;
        if (is_native_lossy) {
            double expected_min = 0.90;
            if (bitrate > 0 && bitrate < 192000) expected_min = 0.75;
            else if (bitrate > 0 && bitrate < 256000) expected_min = 0.85;
            if (cutoff_ratio > 0 && cutoff_ratio < expected_min - 0.08)
                upscaled = 1;
        }

        render_visual_spectrum(
            &analyzer,
            cutoff_hz, steepness, noise_db, roughness, band_ratio,
            is_transcode, is_native_lossy, upscaled,
            peak_db, opts->threshold_db,
            filename, fmt_name,
            sample_rate, channels, analyzer.count,
            opts->fft_size, bitrate);

        analyzer_free(&analyzer);
        if (opts->auto_remove) maybe_remove(filename, peak_db < -90.0, is_native_lossy, upscaled, is_transcode);
        if (is_native_lossy)
            return upscaled ? 1 : 0;
        else
            return is_transcode > 0 ? 1 : 0;
    }

    /* ---- Plain text output ---- */
    printf("\n");
    {
        int tw = get_term_width();
        int flen = (int)strlen(filename);
        printf(ANSI_BG_GREY ANSI_BOLD ANSI_CYAN "File:" ANSI_RESET ANSI_BG_GREY "         %s", filename);
        int used = 14 + flen;
        if (used < tw) repeat_char(' ', tw - used);
        printf(ANSI_RESET "\n");
    }
    printf(ANSI_BOLD ANSI_CYAN "Format:" ANSI_RESET "       %s\n", fmt_name);
    printf(ANSI_BOLD ANSI_CYAN "Sample rate:" ANSI_RESET "  %d Hz\n", sample_rate);
    printf(ANSI_BOLD ANSI_CYAN "Channels:" ANSI_RESET "     %d\n", channels);
    printf(ANSI_BOLD ANSI_CYAN "Windows:" ANSI_RESET "      %d\n", analyzer.count);
    printf(ANSI_BOLD ANSI_CYAN "Peak:" ANSI_RESET "         %.1f dBFS\n", peak_db);
    printf(ANSI_BOLD ANSI_CYAN "Cutoff:" ANSI_RESET "       %.0f Hz (%.1f%% of Nyquist)\n", cutoff_hz, 100.0 * cutoff_hz / nyquist);
    printf(ANSI_BOLD ANSI_CYAN "Steepness:" ANSI_RESET "    %.0f Hz\n", steepness);
    printf(ANSI_BOLD ANSI_CYAN "Roughness:" ANSI_RESET "    %.3f\n", roughness);
    printf(ANSI_BOLD ANSI_CYAN "Band ratio:" ANSI_RESET "   %.3f\n", band_ratio);
    printf(ANSI_BOLD ANSI_CYAN "Noise floor:" ANSI_RESET "  %.1f dB\n", noise_db);
    printf(ANSI_BOLD ANSI_CYAN "Verdict:" ANSI_RESET "      ");

    if (peak_db < -90.0) {
        printf(ANSI_RED "SILENT" ANSI_RESET " (no detectable audio content)\n");
        analyzer_free(&analyzer);
        if (opts->auto_remove) maybe_remove(filename, 1, 0, 0, 0);
        return 2;
    }

    double cutoff_ratio = cutoff_hz / nyquist;
    int upscaled = 0;

    if (is_native_lossy) {
        double expected_min = 0.90;
        if (bitrate > 0 && bitrate < 192000) expected_min = 0.75;
        else if (bitrate > 0 && bitrate < 256000) expected_min = 0.85;

        if (cutoff_ratio > 0 && cutoff_ratio < expected_min - 0.08)
            upscaled = 1;

        if (upscaled) {
            printf(ANSI_YELLOW "UPSCALED" ANSI_RESET " (re-encoded from a lower-bitrate source)\n");
            printf(ANSI_BOLD ANSI_CYAN "Verdict Info:" ANSI_RESET " cut-off suggests ");
            if (cutoff_ratio < 0.70)
                printf(ANSI_BOLD "<= 64 kbps" ANSI_RESET " source\n");
            else if (cutoff_ratio < 0.80)
                printf(ANSI_BOLD "96-128 kbps" ANSI_RESET " source\n");
            else if (cutoff_ratio < 0.88)
                printf(ANSI_BOLD "128-192 kbps" ANSI_RESET " source\n");
        } else {
            printf(ANSI_GREEN "NATIVE" ANSI_RESET " (single encode at this bitrate)\n");
        }
    } else {
        if (is_transcode)
            printf(ANSI_YELLOW "TRANSCODE" ANSI_RESET " (lossy -> lossless re-encode detected)\n");
        else
            printf(ANSI_GREEN "GENUINE" ANSI_RESET " (likely native lossless)\n");
    }

    analyzer_free(&analyzer);
    if (opts->auto_remove) maybe_remove(filename, peak_db < -90.0, is_native_lossy, upscaled, is_transcode);
    if (is_native_lossy)
        return upscaled ? 1 : 0;
    else
        return is_transcode > 0 ? 1 : 0;
}

/* ---- Directory walker ---- */

static int process_path(const char *path, const Options *opts)
{
    struct stat st;
    if (stat(path, &st) < 0) {
        fprintf(stderr, "Error: cannot access '%s' (%s).\n", path, strerror(errno));
        return 1;
    }

    if (!S_ISDIR(st.st_mode))
        return process_file(path, opts);

    /* Strip trailing slash so we don't double it */
    size_t plen = strlen(path);
    while (plen > 1 && path[plen - 1] == '/') plen--;

    DIR *dir = opendir(path);
    if (!dir) {
        fprintf(stderr, "Error: cannot open directory '%s' (%s).\n", path, strerror(errno));
        return 1;
    }

    int overall = 0;
    struct dirent *e;
    while ((e = readdir(dir))) {
        if (e->d_name[0] == '.') continue;

        size_t nlen = strlen(e->d_name);
        char *full = malloc(plen + 1 + nlen + 1);
        if (!full) continue;
        memcpy(full, path, plen);
        full[plen] = '/';
        memcpy(full + plen + 1, e->d_name, nlen + 1);

        struct stat st;
        if (stat(full, &st) < 0) {
            free(full);
            continue;
        }

        if (S_ISDIR(st.st_mode)) {
            if (opts->recursive) {
                int rc = process_path(full, opts);
                free(full);
                if (rc > overall) overall = rc;
            } else {
                free(full);
            }
            continue;
        }

        if (!is_audio_ext(e->d_name)) {
            free(full);
            continue;
        }

        int rc = process_path(full, opts);
        free(full);
        if (rc > overall) overall = rc;
    }
    closedir(dir);
    return overall;
}

/* ---- FFmpeg log filter (silences non-fatal chatter) ---- */

static void quiet_log(void *avcl, int level, const char *fmt, va_list vl)
{
    (void)avcl;
    if (level > AV_LOG_ERROR) return;
    vfprintf(stderr, fmt, vl);
}

/* ---- Main ---- */

int main(int argc, char **argv)
{
    av_log_set_callback(quiet_log);

    const char *prog = argv[0];

    Options opts = {
        .threshold_db  = -(40.0 + (double)(THRESHOLD_DEFAULT - 1) * 40.0 / 98.0),
        .sensitivity   = 0.5,
        .fft_size      = FFT_SIZE_DEFAULT,
        .max_secs      = MAX_ANALYSIS_SECS,
        .verbose       = 0,
        .dump_spectrum = 0,
        .visual        = 0,
        .auto_remove   = 0,
        .recursive     = 0,
        .full          = 0,
    };

    static const struct option long_opts[] = {
        {"threshold", required_argument, NULL, 't'},
        {"fft-size",  required_argument, NULL, 'f'},
        {"duration",  required_argument, NULL, 'd'},
        {"verbose",   no_argument,       NULL, 'v'},
        {"spectrum",  no_argument,       NULL, 's'},
        {"visual",    no_argument,       NULL, 'V'},
        {"recursive", no_argument,      NULL, 'r'},
        {"full",      no_argument,       NULL, 'F'},
        {"auto-remove", no_argument,     NULL, 'a'},
        {"help",      no_argument,       NULL, 'h'},
        {NULL, 0, NULL, 0}
    };

    int opt;
    while ((opt = getopt_long(argc, argv, "t:f:d:arFsvVh", long_opts, NULL)) != -1) {
        switch (opt) {
        case 't': {
            int pct = atoi(optarg);
            if (pct > 99) pct = 99;
            if (pct < 1) pct = 1;
            opts.threshold_db = -(40.0 + (double)(pct - 1) * 40.0 / 98.0);
            opts.sensitivity  = (double)(pct - 1) / 98.0;
            break;
        }
        case 'f': opts.fft_size      = atoi(optarg); break;
        case 'd': opts.max_secs      = atoi(optarg); break;
        case 'a': opts.auto_remove   = 1;            break;
        case 'r': opts.recursive     = 1;            break;
        case 'F': opts.full          = 1;            break;
        case 's': opts.visual        = 1;            break;
        case 'v': opts.verbose       = 1;            break;
        case 'V': opts.visual        = 1;            break;
        case 'h': print_help(prog); return 0;
        default:  print_help(prog); return 1;
        }
    }

    if (optind >= argc) {
        print_help(prog);
        return 0;
    }

    if (opts.fft_size < 64 || opts.fft_size > 65536 || (opts.fft_size & (opts.fft_size - 1)) != 0) {
        fprintf(stderr, "Error: FFT size must be a power of 2 between 64 and 65536.\n");
        return 1;
    }

    int overall = 0;
    for (int i = optind; i < argc; i++) {
        int rc = process_path(argv[i], &opts);
        if (rc > overall) overall = rc;
    }
    return overall;
}