#include "xtc/xtc_dsp.h"
#include "../graph/graph_internal.h"
#include <math.h>
#include <stdlib.h>
#include <string.h>

#define XTC_TAU 6.28318530717958647692

struct xtc_plan {
    size_t node_count, max_frames;
    xtc_node *nodes;
    size_t *order, *offsets, *sources;
    unsigned char *render;
    float *buffers, *peaks;
    double *phases;
    double sample_rate;
    float input_gain;
    uint64_t position;
    xtc_native **native;
    xtc_plugin **plugins;
};

/**
 * @brief Releases a compiled plan and all resources it owns.
 *
 * @param plan Plan to destroy; NULL is accepted.
 */
void xtc_plan_destroy(xtc_plan *plan)
{
    if (plan == NULL)
        return;
    if (plan->native) {
        size_t i;
        for (i = 0; i < plan->node_count * 2; ++i)
            xtc_native_destroy(plan->native[i]);
    }
    if (plan->plugins) {
        size_t i;
        for (i = 0; i < plan->node_count * 2; ++i) xtc_plugin_destroy(plan->plugins[i]);
    }
    free(plan->plugins);
    free(plan->native);
    free(plan->nodes);
    free(plan->order);
    free(plan->offsets);
    free(plan->sources);
    free(plan->render);
    free(plan->buffers);
    free(plan->peaks);
    free(plan->phases);
    free(plan);
}

/**
 * @brief Allocates an independent execution plan with preallocated processing buffers.
 *
 * @param graph Graph model; borrowed for this call.
 * @param sample_rate Sample rate in hertz.
 * @param max_frames Maximum frames per processing block.
 * @param out_plan Receives the newly allocated plan; caller owns it on success.
 * @return XTC_OK on success, or an error code describing the failure.
 */
xtc_result xtc_graph_compile(const xtc_graph *graph, double sample_rate, size_t max_frames, xtc_plan **out_plan)
{
    xtc_plan *plan;
    xtc_result result;
    size_t node, edge, storage_nodes, cursor = 0U;
    int has_output = 0;
    if (out_plan == NULL)
        return XTC_ERR_INVALID_ARGUMENT;
    *out_plan = NULL;
    if (graph == NULL || !isfinite(sample_rate) || sample_rate <= 0.0 || max_frames == 0U ||
        max_frames > XTC_MAX_FRAMES)
        return XTC_ERR_INVALID_ARGUMENT;
    storage_nodes = graph->node_count == 0U ? 1U : graph->node_count;
    for (node = 0U; node < graph->node_count; ++node) {
        if (graph->nodes[node].type == XTC_NODE_OSCILLATOR && (double)graph->nodes[node].value > sample_rate * 0.5)
            return XTC_ERR_INVALID_ARGUMENT;
        if (graph->nodes[node].type == XTC_NODE_OUTPUT)
            has_output = 1;
    }
    /* Fixed graph/frame limits bound all allocation products below. */
    plan = calloc(1U, sizeof(*plan));
    if (plan == NULL)
        return XTC_ERR_OUT_OF_MEMORY;
    plan->node_count = graph->node_count;
    plan->max_frames = max_frames;
    plan->sample_rate = sample_rate;
    plan->input_gain = 1.0f;
    plan->plugins = calloc(storage_nodes * 2U,sizeof(*plan->plugins));
    plan->native = calloc(storage_nodes * 2U, sizeof(*plan->native));
    plan->nodes = calloc(storage_nodes, sizeof(*plan->nodes));
    plan->order = calloc(storage_nodes, sizeof(*plan->order));
    plan->offsets = calloc(plan->node_count + 1U, sizeof(*plan->offsets));
    plan->sources = calloc(graph->edge_count + 1U, sizeof(*plan->sources));
    plan->render = calloc(storage_nodes, sizeof(*plan->render));
    plan->buffers = calloc(storage_nodes * max_frames * 2U, sizeof(*plan->buffers));
    plan->peaks = calloc(storage_nodes, sizeof(*plan->peaks));
    plan->phases = calloc(storage_nodes, sizeof(*plan->phases));
    if (plan->plugins == NULL || plan->native == NULL || plan->nodes == NULL || plan->order == NULL || plan->offsets == NULL ||
        plan->sources == NULL || plan->render == NULL || plan->buffers == NULL || plan->peaks == NULL ||
        plan->phases == NULL) {
        xtc_plan_destroy(plan);
        return XTC_ERR_OUT_OF_MEMORY;
    }
    result = xtc_graph_order(graph, plan->order);
    if (result != XTC_OK) {
        xtc_plan_destroy(plan);
        return result;
    }
    memcpy(plan->nodes, graph->nodes, plan->node_count * sizeof(*plan->nodes));
    for (node = 0U; node < plan->node_count; ++node) {
        int terminal = 1;
        plan->offsets[node] = cursor;
        for (edge = 0U; edge < graph->edge_count; ++edge) {
            if (graph->edges[edge].destination == node)
                plan->sources[cursor++] = graph->edges[edge].source;
            if (graph->edges[edge].source == node)
                terminal = 0;
        }
        plan->render[node] =
            (unsigned char)(has_output || graph->require_output_nodes ? plan->nodes[node].type == XTC_NODE_OUTPUT
                                                                      : terminal);
    }
    for (node = 0; node < plan->node_count; ++node) {
        if (plan->nodes[node].type == XTC_NODE_PLUGIN) {
            size_t side;
            for (side = 0; side < 2; ++side) {
                result = xtc_plugin_create(&plan->nodes[node].plugin,sample_rate,max_frames,
                    &plan->plugins[side * plan->node_count + node]);
                if (result != XTC_OK) { xtc_plan_destroy(plan); return result; }
            }
        }
        if (plan->nodes[node].type == XTC_NODE_NATIVE) {
            size_t side;
            for (side = 0; side < 2; ++side) {
                result = xtc_native_create(&plan->nodes[node].native, sample_rate, max_frames, plan->nodes[node].value,
                                           &plan->native[side * plan->node_count + node]);
                if (result != XTC_OK) {
                    xtc_plan_destroy(plan);
                    return result;
                }
            }
        }
    }
    plan->offsets[plan->node_count] = cursor;
    *out_plan = plan;
    return XTC_OK;
}

/**
 * @brief Resets oscillator phases, meters, and native processor state without allocating.
 *
 * @param plan Compiled graph plan and its single-owner runtime state.
 * @return XTC_OK on success, or an error code describing the failure.
 */
xtc_result xtc_plan_reset(xtc_plan *plan)
{
    if (plan == NULL)
        return XTC_ERR_INVALID_ARGUMENT;
    {
        size_t i;
        for (i = 0; i < plan->node_count * 2; ++i)
            xtc_native_reset(plan->native[i]);
    }
    plan->position = 0;
    memset(plan->phases, 0, plan->node_count * sizeof(*plan->phases));
    memset(plan->peaks, 0, plan->node_count * sizeof(*plan->peaks));
    return XTC_OK;
}

/**
 * @brief Copies the last block's absolute peak for a meter node.
 *
 * @param plan Compiled graph plan and its single-owner runtime state.
 * @param node_id Stable node identifier.
 * @param out_peak Receives the peak.
 * @return XTC_OK on success, or an error code describing the failure.
 */
xtc_result xtc_plan_meter_peak(const xtc_plan *plan, size_t node_id, float *out_peak)
{
    if (plan == NULL || out_peak == NULL)
        return XTC_ERR_INVALID_ARGUMENT;
    size_t index;
    for (index = 0U; index < plan->node_count; ++index)
        if (plan->nodes[index].id == node_id)
            break;
    if (index == plan->node_count)
        return XTC_ERR_NOT_FOUND;
    node_id = index;
    if (plan->nodes[node_id].type != XTC_NODE_METER)
        return XTC_ERR_INVALID_ARGUMENT;
    *out_peak = plan->peaks[node_id];
    return XTC_OK;
}

/**
 * @brief Processes a block with separate stereo timeline and instrument sources.
 *
 * @param plan Compiled graph plan and its single-owner runtime state.
 * @param input Borrowed input sample buffer.
 * @param timeline Borrowed timeline source buffer; NULL means silence.
 * @param timeline_right Borrowed right timeline source buffer; NULL means silence.
 * @param instrument Borrowed instrument source buffer; NULL means silence.
 * @param instrument_right Borrowed right instrument source buffer; NULL means silence.
 * @param output Destination buffer with room for the requested frames.
 * @param right Destination right-channel buffer; NULL selects mono rendering.
 * @param frame_count Number of audio frames.
 * @return XTC_OK on success, or an error code describing the failure.
 */
xtc_result xtc_plan_process_stereo(xtc_plan *plan, const float *input, const float *timeline,
                                   const float *timeline_right, const float *instrument, const float *instrument_right,
                                   float *output, float *right, size_t frame_count)
{
    size_t index, frame, edge, channel;
    if (plan == NULL || output == NULL || (right && right == output))
        return XTC_ERR_INVALID_ARGUMENT;
    if (frame_count > plan->max_frames || plan->position > UINT64_MAX - frame_count)
        return XTC_ERR_CAPACITY;
    if (frame_count == 0U)
        return XTC_OK;
    /* All external input reads finish before output is written, allowing aliasing.
     * Nonfinite input/arithmetic becomes silence per sample, never persistent DSP state. */
    for (channel = 0; channel < (right ? 2U : 1U); ++channel) {
        const float *audio_source = channel ? timeline_right : timeline;
        const float *midi_source = channel ? instrument_right : instrument;
        for (index = 0U; index < plan->node_count; ++index) {
            size_t node = plan->order[index];
            const xtc_node *spec = &plan->nodes[node];
            float *buffer = plan->buffers + (channel * plan->node_count + node) * plan->max_frames;
            float peak = 0.0f;
            double phase = plan->phases[node];
            for (frame = 0U; frame < frame_count; ++frame) {
                float sample = 0.0f;
                if (spec->type == XTC_NODE_INSTRUMENT) {
                    sample = midi_source ? midi_source[frame] : 0.0f;
                } else if (spec->type == XTC_NODE_AUDIO) {
                    sample = audio_source ? audio_source[frame] : 0.0f;
                } else if (spec->type == XTC_NODE_OSCILLATOR) {
                    sample = (float)sin(XTC_TAU * phase);
                    phase += (double)spec->value / plan->sample_rate;
                    if (phase >= 1.0)
                        phase -= 1.0;
                } else {
                    if (plan->offsets[node] == plan->offsets[node + 1U])
                        sample = input == NULL ? 0.0f : input[frame] * plan->input_gain;
                    for (edge = plan->offsets[node]; edge < plan->offsets[node + 1U]; ++edge)
                        sample += plan->buffers[(channel * plan->node_count + plan->sources[edge]) * plan->max_frames +
                                                frame];
                    if (spec->type == XTC_NODE_GAIN)
                        sample *= spec->value;
                }
                sample = xtc_dsp_finite(sample);
                buffer[frame] = sample;
                if (fabsf(sample) > peak)
                    peak = fabsf(sample);
            }
            if (spec->type == XTC_NODE_NATIVE) {
                xtc_native_block block = {spec->native.kind == XTC_NATIVE_EFFECT ? buffer : NULL,
                                          buffer,
                                          frame_count,
                                          plan->position,
                                          NULL,
                                          0};
                xtc_result result = xtc_native_process(plan->native[channel * plan->node_count + node], &block);
                if (result != XTC_OK) {
                    memset(output, 0, frame_count * sizeof(*output));
                    if (right)
                        memset(right, 0, frame_count * sizeof(*right));
                    return result;
                }
            }
            if (spec->type == XTC_NODE_PLUGIN) {
                xtc_result result = xtc_plugin_process(plan->plugins[channel * plan->node_count + node],
                    spec->plugin.inputs ? buffer : NULL,buffer,frame_count);
                if (result != XTC_OK) {
                    memset(output,0,frame_count*sizeof(*output));
                    if (right) memset(right,0,frame_count*sizeof(*right));
                    return result;
                }
            }
            if (!right || channel == 1)
                plan->phases[node] = phase;
            if (spec->type == XTC_NODE_METER)
                plan->peaks[node] = channel && plan->peaks[node] > peak ? plan->peaks[node] : peak;
        }
    }
    /* Finish both channels before writing either caller buffer. */
    for (channel = 0; channel < (right ? 2U : 1U); ++channel) {
        float *destination = channel ? right : output;
        for (frame = 0U; frame < frame_count; ++frame) {
            float sample = 0.0f;
            for (index = 0U; index < plan->node_count; ++index)
                if (plan->render[index])
                    sample += plan->buffers[(channel * plan->node_count + index) * plan->max_frames + frame];
            destination[frame] = xtc_dsp_finite(sample);
        }
    }
    plan->position += frame_count;
    return XTC_OK;
}

/**
 * @brief Compiles at 48000 Hz, applies input gain, renders once, and releases temporary state.
 *
 * @param graph Graph model; borrowed for this call.
 * @param input Borrowed input sample buffer.
 * @param output Destination buffer with room for the requested frames.
 * @param frame_count Number of audio frames.
 * @param input_gain Finite linear gain applied to external input before processing.
 * @return XTC_OK on success, or an error code describing the failure.
 */
xtc_result xtc_graph_process_offline(xtc_graph *graph, const float *input, float *output, size_t frame_count,
                                     float input_gain)
{
    xtc_plan *plan = NULL;
    xtc_result result;
    if (input == NULL || output == NULL || !isfinite(input_gain))
        return XTC_ERR_INVALID_ARGUMENT;
    result = xtc_graph_compile(graph, 48000.0, frame_count == 0U ? 1U : frame_count, &plan);
    if (result != XTC_OK)
        return result;
    plan->input_gain = input_gain;
    result = xtc_plan_process(plan, input, output, frame_count);
    xtc_plan_destroy(plan);
    return result;
}

/**
 * @brief Processes a mono block with external input and no timeline or instrument sources.
 *
 * @param plan Compiled graph plan and its single-owner runtime state.
 * @param input Borrowed input sample buffer.
 * @param output Destination buffer with room for the requested frames.
 * @param frames Number of audio frames.
 * @return XTC_OK on success, or an error code describing the failure.
 */
xtc_result xtc_plan_process(xtc_plan *plan, const float *input, float *output, size_t frames)
{
    return xtc_plan_process_audio(plan, input, NULL, output, frames);
}

/**
 * @brief Processes a mono block with timeline audio and no instrument source.
 *
 * @param plan Compiled graph plan and its single-owner runtime state.
 * @param input Borrowed input sample buffer.
 * @param timeline Borrowed timeline source buffer; NULL means silence.
 * @param output Destination buffer with room for the requested frames.
 * @param frames Number of audio frames.
 * @return XTC_OK on success, or an error code describing the failure.
 */
xtc_result xtc_plan_process_audio(xtc_plan *plan, const float *input, const float *timeline, float *output,
                                  size_t frames)
{
    return xtc_plan_process_sources(plan, input, timeline, NULL, output, frames);
}

/**
 * @brief Processes a mono block with separate timeline and instrument sources.
 *
 * @param p Compiled graph plan and its single-owner runtime state.
 * @param in Borrowed mono input buffer; NULL means silence.
 * @param audio Borrowed timeline source buffer; NULL means silence.
 * @param midi Borrowed instrument source buffer; NULL means silence.
 * @param out Destination sample buffer with room for the requested frames.
 * @param frames Number of audio frames.
 * @return XTC_OK on success, or an error code describing the failure.
 */
xtc_result xtc_plan_process_sources(xtc_plan *p, const float *in, const float *audio, const float *midi, float *out,
                                    size_t frames)
{
    return xtc_plan_process_stereo(p, in, audio, NULL, midi, NULL, out, NULL, frames);
}