#include "sequencer_widget.hpp"
#include "xtc/xtc_midi.h"
#include <FL/Fl.H>
#include <FL/Fl_Scroll.H>
#include <FL/fl_draw.H>
#include <FL/fl_ask.H>
#include <FL/Fl_Menu_Item.H>
#include <algorithm>
#include <cstdio>

/**
 * @brief Constructs the timeline widget with a borrowed project and seek callback.
 *
 * @param left Left coordinate in pixels.
 * @param top Top coordinate in pixels.
 * @param project Borrowed project; must outlive the widget's use of it.
 * @param seek Callback used to request a transport seek.
 * @param context Opaque callback context.
 */
SequencerWidget::SequencerWidget(int left, int top, xtc_project *project, Seek seek, void *context)
    : Fl_Widget(left, top, 6300, 3700), project_(project), seek_(seek), context_(context)
{
    extent();
}

/**
 * @brief Replaces the borrowed project and refreshes the widget's displayed state.
 *
 * @param project Borrowed project; must outlive the widget's use of it.
 * @param reset Whether to clear selection, cursor, and drag state.
 */
void SequencerWidget::set_project(xtc_project *project, bool reset)
{
    project_ = project;
    if (reset) {
        track_ = clip_ = UINT64_MAX;
        cursor_ = 0;
        mode_ = 0;
    }
    extent();
    redraw();
}

/**
 * @brief Converts a screen x coordinate to a bounded timeline tick snapped to a sixteenth note.
 *
 * @param px Screen x coordinate in pixels.
 * @return Snapped tick within the supported project range.
 */
uint64_t SequencerWidget::tick(int px) const
{
    return std::min(XTC_PROJECT_MAX_TICK, static_cast<uint64_t>(std::max(0, px - x() - 120)) * 960U /
                                              static_cast<unsigned int>(scale_) / grid_ * grid_);
}

/**
 * @brief Resizes the timeline's scrollable area to fit its tracks and clip ends.
 */
void SequencerWidget::extent()
{
    size_t tracks, clips;
    xtc_project_get_counts(project_, &tracks, &clips);
    uint64_t end = 32U * 3840U;
    for (size_t i = 0; i < clips; ++i) {
        xtc_clip_info c{};
        xtc_project_get_clip(project_, i, &c);
        end = std::max(end, c.start_tick + c.length_tick + 3840U);
    }
    size(static_cast<int>(end * static_cast<unsigned int>(scale_) / 960U + 140U),
         std::max(400, static_cast<int>(tracks) * 56 + 100));
    if (parent())
        parent()->redraw();
}

/**
 * @brief Reports an edit result, refreshes the widget, and notifies listeners on success.
 *
 * @param result Result of the attempted operation.
 */
void SequencerWidget::changed(xtc_result result)
{
    if (result != XTC_OK)
        fl_alert("%s", xtc_result_string(result));
    else {
        extent();
        do_callback();
    }
    redraw();
}

/**
 * @brief Creates and selects a track through the arrangement edit hook.
 * @return XTC_OK on success, or an error code describing the failure.
 */
xtc_result SequencerWidget::add_track()
{
    if (before_edit) {
        xtc_result r = before_edit(context_);
        if (r != XTC_OK) {
            changed(r);
            return r;
        }
    }
    uint64_t id;
    xtc_result r = xtc_project_add_track(project_, "Track", &id);
    if (r == XTC_OK) {
        track_ = id;
        clip_ = UINT64_MAX;
    }
    changed(r);
    return r;
}

/**
 * @brief Creates and selects a one-bar silent region at the timeline cursor.
 * @return XTC_OK on success, or an error code describing the failure.
 */
xtc_result SequencerWidget::add_region()
{
    if (before_edit) {
        xtc_result r = before_edit(context_);
        if (r != XTC_OK) {
            changed(r);
            return r;
        }
    }
    size_t tracks, clips;
    xtc_project_get_counts(project_, &tracks, &clips);
    if (track_ == UINT64_MAX && tracks) {
        xtc_track_info t{};
        xtc_project_get_track(project_, 0, &t);
        track_ = t.id;
    }
    uint64_t id;
    xtc_result r = xtc_project_add_clip(project_, track_, "Region (silent)", cursor_, 3840U, &id);
    if (r == XTC_OK)
        clip_ = id;
    changed(r);
    return r;
}

/**
 * @brief Creates and selects a one-bar MIDI clip at the timeline cursor.
 * @return XTC_OK on success, or an error code describing the failure.
 */
xtc_result SequencerWidget::add_midi_clip()
{
    xtc_result r = before_edit ? before_edit(context_) : XTC_OK;
    uint64_t id;
    if (r == XTC_OK) {
        if (track_ == UINT64_MAX) {
            xtc_track_info t{};
            r = xtc_project_get_track(project_, 0, &t);
            track_ = r == XTC_OK ? t.id : UINT64_MAX;
        }
        if (r == XTC_OK)
            r = xtc_project_add_midi_clip(project_, track_, cursor_, 3840, &id);
        if (r == XTC_OK)
            clip_ = id;
    }
    changed(r);
    return r;
}

/**
 * @brief Removes the selected clip, or the selected track when no clip is selected.
 * @return XTC_OK on success, or an error code describing the failure.
 */
xtc_result SequencerWidget::delete_selection()
{
    if (before_edit) {
        xtc_result r = before_edit(context_);
        if (r != XTC_OK) {
            changed(r);
            return r;
        }
    }
    xtc_result r =
        clip_ != UINT64_MAX ? xtc_project_remove_clip(project_, clip_) : xtc_project_remove_track(project_, track_);
    if (r == XTC_OK)
        clip_ = track_ = UINT64_MAX;
    changed(r);
    return r;
}

/**
 * @brief Adjusts timeline zoom within its supported bounds and updates the scroll extent.
 *
 * @param direction Zoom direction; positive zooms in, nonpositive zooms out.
 */
void SequencerWidget::zoom(int direction)
{
    scale_ = std::clamp(direction > 0 ? scale_ * 2 : scale_ / 2, 24, 384);
    extent();
    redraw();
}

/**
 * @brief Draws the widget's current model, selection, and interaction feedback.
 */
void SequencerWidget::draw()
{
    fl_push_clip(x(), y(), w(), h());
    fl_color(fl_rgb_color(35, 38, 43));
    fl_rectf(x(), y(), w(), h());
    int cx, cy, cw, ch;
    fl_clip_box(x(), y(), w(), h(), cx, cy, cw, ch);
    fl_font(FL_HELVETICA, 12);
    int first = std::max(0, (cx - x() - 120) / (scale_ * 4));
    int last = (cx + cw - x() - 120) / (scale_ * 4) + 1;
    for (int bar = first; bar <= last; ++bar) {
        int px = x() + 120 + bar * scale_ * 4;
        fl_color(fl_rgb_color(65, 68, 74));
        fl_line(px, y(), px, y() + h());
        char label[32];
        std::snprintf(label, sizeof(label), "%d", bar + 1);
        fl_color(FL_WHITE);
        fl_draw(label, px + 4, y() + 19);
    }
    char tempo[32];
    std::snprintf(tempo, sizeof(tempo), "%.3g BPM | 4/4", xtc_project_tempo(project_) / 1000.0);
    fl_color(FL_WHITE);
    fl_draw(tempo, x() + 4, y() + 19);
    size_t tracks, clips;
    xtc_project_get_counts(project_, &tracks, &clips);
    for (size_t i = 0; i < tracks; ++i) {
        xtc_track_info t{};
        xtc_project_get_track(project_, i, &t);
        int py = y() + 28 + static_cast<int>(i) * 56;
        fl_color(t.id == track_ ? fl_rgb_color(70, 90, 110) : fl_rgb_color(48, 51, 57));
        fl_rectf(x(), py, 118, 55);
        fl_color(FL_WHITE);
        fl_draw(t.name, x() + 6, py + 32);
        for (size_t j = 0; j < clips; ++j) {
            xtc_clip_info c{};
            xtc_project_get_clip(project_, j, &c);
            if (c.track_id != t.id)
                continue;
            int left = x() + 120 + static_cast<int>(c.start_tick * static_cast<unsigned int>(scale_) / 960U);
            int right = left + std::max(4, static_cast<int>(c.length_tick * static_cast<unsigned int>(scale_) / 960U));
            int a = std::max(left, cx), b = std::min(right, cx + cw);
            if (b <= a || py + 50 < cy || py > cy + ch)
                continue;
            fl_color(c.id == clip_ ? fl_rgb_color(100, 170, 205) : fl_rgb_color(65, 120, 150));
            fl_rectf(a, py + 5, b - a, 44);
            fl_push_clip(a, py + 5, b - a, 44);
            fl_color(FL_WHITE);
            char label[96];
            std::snprintf(label,sizeof(label),"%s: %s",c.midi ? "MIDI" : c.asset_path[0] ? "Audio" : "Region",c.name);
            fl_draw(label,std::max(a,left+6),py+31);
            fl_pop_clip();
        }
    }
    int playhead = x() + 120 + static_cast<int>(cursor_ * static_cast<unsigned int>(scale_) / 960U);
    if (playhead >= cx && playhead <= cx + cw) {
        fl_color(FL_RED);
        fl_line(playhead, y(), playhead, y() + h());
    }
    fl_pop_clip();
}

/**
 * @brief Handles FLTK input events and delegates unhandled events to the base widget.
 *
 * @param event FLTK event code.
 * @return Nonzero if the event was handled, zero otherwise.
 */
int SequencerWidget::handle(int event)
{
    if (event == FL_PUSH && (Fl::event_button() == FL_LEFT_MOUSE || Fl::event_button() == FL_RIGHT_MOUSE)) {
        take_focus();
        mode_ = 0;
        if (Fl::event_y() < y() + 28) {
            uint64_t target = tick(Fl::event_x());
            xtc_result r = seek_(context_, target);
            if (r == XTC_OK)
                cursor_ = target;
            else
                fl_alert("Stop playback before seeking: %s", xtc_result_string(r));
            redraw();
            return 1;
        }
        size_t tracks, clips;
        xtc_project_get_counts(project_, &tracks, &clips);
        int row = (Fl::event_y() - y() - 28) / 56;
        if (row < 0 || static_cast<size_t>(row) >= tracks)
            return 1;
        xtc_track_info t{};
        xtc_project_get_track(project_, static_cast<size_t>(row), &t);
        track_ = t.id;
        clip_ = UINT64_MAX;
        for (size_t j = clips; j > 0; --j) {
            xtc_clip_info c{};
            xtc_project_get_clip(project_, j - 1, &c);
            int left = x() + 120 + static_cast<int>(c.start_tick * static_cast<unsigned int>(scale_) / 960U);
            int right = left + static_cast<int>(c.length_tick * static_cast<unsigned int>(scale_) / 960U);
            if (c.track_id == track_ && Fl::event_x() >= left && Fl::event_x() < right) {
                clip_ = c.id;
                original_ = c;
                drag_x_ = Fl::event_x();
                mode_ = Fl::event_x() - left < 7 ? 2 : right - Fl::event_x() < 7 ? 3 : 1;
                break;
            }
        }
        if (Fl::event_button() == FL_RIGHT_MOUSE) {
            mode_ = 0;
            Fl_Menu_Item items[4]{};
            items[0].text = "Duplicate clip (Ctrl+D)"; items[1].text = "Rename (F2)"; items[2].text = "Delete (undoable)";
            const Fl_Menu_Item *picked = items->popup(Fl::event_x(),Fl::event_y());
            if (picked == items) duplicate_selection();
            else if (picked == items+1) { const char *name = fl_input("Name (1..63 UTF-8 bytes)",""); if (name) rename_selection(name); }
            else if (picked == items+2) delete_selection();
        }
        redraw();
        return 1;
    }
    if (event == FL_DRAG)
        return mode_ != 0;
    if (event == FL_RELEASE && mode_) {
        int mode = mode_;
        mode_ = 0;
        int64_t delta = static_cast<int64_t>(Fl::event_x() - drag_x_) * 960 / scale_ / static_cast<int64_t>(grid_) * static_cast<int64_t>(grid_);
        int64_t start = static_cast<int64_t>(original_.start_tick);
        int64_t length = static_cast<int64_t>(original_.length_tick);
        int64_t offset = static_cast<int64_t>(original_.offset_tick);
        uint64_t target = original_.track_id;
        if (mode == 1) {
            start = std::max<int64_t>(0, start + delta);
            int row = (Fl::event_y() - y() - 28) / 56;
            xtc_track_info t{};
            if (row >= 0 && xtc_project_get_track(project_, static_cast<size_t>(row), &t) == XTC_OK)
                target = t.id;
        } else if (mode == 2) {
            start += delta;
            offset += delta;
            length -= delta;
        } else
            length += delta;
        if (start < 0 || offset < 0 || length <= 0)
            return 1;
        if (before_edit) {
            xtc_result r = before_edit(context_);
            if (r != XTC_OK) {
                changed(r);
                return 1;
            }
        }
        changed(xtc_project_edit_clip(project_, clip_, target, static_cast<uint64_t>(start),
                                      static_cast<uint64_t>(length), static_cast<uint64_t>(offset)));
        return 1;
    }
    if (event == FL_KEYDOWN && Fl::event_state(FL_CTRL) && Fl::event_key() == 'd') { duplicate_selection(); return 1; }
    if (event == FL_KEYDOWN && Fl::event_key() == FL_F+2) {
        const char *name = fl_input("Name (1..63 UTF-8 bytes)",""); if (name) rename_selection(name); return 1;
    }
    if (event == FL_KEYDOWN && Fl::event_state(FL_ALT) &&
        (Fl::event_key() == FL_Up || Fl::event_key() == FL_Down)) { move_track(Fl::event_key() == FL_Up ? -1 : 1); return 1; }
    if (event == FL_KEYDOWN && Fl::event_key() == FL_Escape) {
        mode_ = 0;
        return 1;
    }
    if (event == FL_KEYDOWN && Fl::event_key() == FL_Delete) {
        delete_selection();
        return 1;
    }
    if (event == FL_FOCUS || event == FL_UNFOCUS)
        return 1;
    return Fl_Widget::handle(event);
}

xtc_result SequencerWidget::grid(uint64_t ticks)
{
    if (ticks != 1 && ticks != 120 && ticks != 240 && ticks != 480 && ticks != 960) return XTC_ERR_INVALID_ARGUMENT;
    grid_ = ticks; redraw(); return XTC_OK;
}
xtc_result SequencerWidget::duplicate_selection()
{
    xtc_clip_info c{}; uint64_t id;
    xtc_result r = xtc_project_find_clip(project_,clip_,&c);
    if (r == XTC_OK && before_edit) r = before_edit(context_);
    if (r == XTC_OK) r = xtc_project_duplicate_clip(project_,clip_,c.track_id,c.start_tick+c.length_tick,&id);
    if (r == XTC_OK) clip_ = id;
    changed(r); return r;
}
xtc_result SequencerWidget::rename_selection(const char *name)
{
    xtc_result r = before_edit ? before_edit(context_) : XTC_OK;
    if (r == XTC_OK) r = clip_ != UINT64_MAX ? xtc_project_rename_clip(project_,clip_,name) : xtc_project_rename_track(project_,track_,name);
    changed(r); return r;
}
xtc_result SequencerWidget::move_track(int direction)
{
    size_t tracks, clips, i; xtc_project_get_counts(project_,&tracks,&clips);
    xtc_track_info track{};
    for (i = 0; i < tracks; ++i) { xtc_project_get_track(project_,i,&track); if (track.id == track_) break; }
    if (i == tracks || (direction < 0 ? i == 0 : i+1 == tracks)) return XTC_ERR_NOT_FOUND;
    xtc_result r = before_edit ? before_edit(context_) : XTC_OK;
    if (r == XTC_OK) r = xtc_project_move_track(project_,track_,direction < 0 ? i-1 : i+1);
    changed(r); return r;
}