#include "mixer_widget.hpp"
#include <FL/Fl.H>
#include <FL/Fl_Box.H>
#include <FL/Fl_Check_Button.H>
#include <FL/Fl_Choice.H>
#include <FL/Fl_Progress.H>
#include <FL/Fl_Value_Input.H>
#include <FL/Fl_Value_Slider.H>
#include <FL/fl_ask.H>
#include <FL/fl_draw.H>
#include <algorithm>
#include <cmath>
#include <cstdio>
#include <string>
#include <vector>

namespace {
constexpr uint64_t lane_ticks = 15360;
}

class AutomationLane : public Fl_Widget {
    MixerWidget &mixer_;

  public:
    /**
     * @brief Creates an automation lane bound to its owning mixer.
     *
     * @param x Left edge in parent coordinates.
     * @param y Top edge in parent coordinates.
     * @param w Lane width in pixels; tick math requires a value greater than 1.
     * @param h Lane height in pixels.
     * @param m Mixer that owns the lane; stored by reference and must outlive it.
     */
    AutomationLane(int x, int y, int w, int h, MixerWidget &m) : Fl_Widget(x, y, w, h), mixer_(m)
    {
    }

    /**
     * @brief Draws the lane grid, automation curve, points, and empty hint.
     *
     * Points for the selected track and parameter are sorted by tick, rendered
     * as an interpolated curve, and marked within the visible tick range.
     */
    void draw() override
    {
        fl_push_clip(x(), y(), w(), h());
        fl_color(fl_rgb_color(32, 35, 40));
        fl_rectf(x(), y(), w(), h());
        fl_font(FL_HELVETICA, 11);
        for (int i = 0; i <= 16; ++i) {
            int px = x() + i * (w() - 1) / 16;
            fl_color(fl_rgb_color(i % 4 ? 55 : 95, 60, 65));
            fl_line(px, y(), px, y() + h());
            if (i % 4 == 0) {
                char label[32];
                std::snprintf(label, sizeof(label), "%llu",
                              static_cast<unsigned long long>(mixer_.lane_start() + static_cast<uint64_t>(i) * 960));
                fl_color(FL_WHITE);
                fl_draw(label, px + 3, y() + 14);
            }
        }
        size_t count = 0;
        xtc_project_automation_count(mixer_.project(), &count);
        std::vector<xtc_automation_point> points;
        for (size_t i = 0; i < count; ++i) {
            xtc_automation_point a{};
            xtc_project_get_automation(mixer_.project(), i, &a);
            if (a.track_id == mixer_.selected_track() && a.parameter == mixer_.parameter())
                points.push_back(a);
        }
        std::sort(points.begin(), points.end(), [](const auto &a, const auto &b) {
            return a.tick < b.tick;
        });
        float min = mixer_.parameter() == XTC_AUTOMATION_GAIN ? 0.0f : -1.0f;
        float range = mixer_.parameter() == XTC_AUTOMATION_GAIN ? 4.0f : 2.0f;
        auto py = [&](float v) {
            return y() + h() - 6 - static_cast<int>((v - min) / range * (h() - 28));
        };
        auto value = [&](uint64_t tick) {
            if (points.empty())
                return min;
            auto it = std::upper_bound(points.begin(), points.end(), tick, [](uint64_t t, const auto &a) {
                return t < a.tick;
            });
            if (it == points.begin())
                return it->value;
            if (it == points.end())
                return points.back().value;
            const auto &a = *(it - 1);
            return a.value +
                   static_cast<float>(static_cast<double>(tick - a.tick) / static_cast<double>(it->tick - a.tick)) *
                       (it->value - a.value);
        };
        fl_color(fl_rgb_color(105, 200, 150));
        if (!points.empty())
            for (int px = 1; px < w(); ++px) {
                uint64_t a =
                    mixer_.lane_start() + static_cast<uint64_t>(px - 1) * lane_ticks / static_cast<uint64_t>(w() - 1);
                uint64_t b =
                    mixer_.lane_start() + static_cast<uint64_t>(px) * lane_ticks / static_cast<uint64_t>(w() - 1);
                fl_line(x() + px - 1, py(value(a)), x() + px, py(value(b)));
            }
        for (const auto &a : points)
            if (a.tick >= mixer_.lane_start() && a.tick <= mixer_.lane_start() + lane_ticks) {
                int px = x() +
                         static_cast<int>((a.tick - mixer_.lane_start()) * static_cast<uint64_t>(w() - 1) / lane_ticks);
                fl_rectf(px - 4, py(a.value) - 4, 8, 8);
            }
        if (points.empty()) {
            fl_color(FL_WHITE);
            fl_draw("Click to add automation; right-click a point to remove. Values replace the "
                    "static control.",
                    x() + 12, y() + h() / 2);
        }
        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 handle(int event) override
    {
        if (event != FL_PUSH)
            return Fl_Widget::handle(event);
        if (Fl::event_button() != FL_LEFT_MOUSE && Fl::event_button() != FL_RIGHT_MOUSE)
            return 0;
        uint64_t tick = mixer_.lane_start() + static_cast<uint64_t>(std::clamp(Fl::event_x() - x(), 0, w() - 1)) *
                                                  lane_ticks / static_cast<uint64_t>(w() - 1);
        tick = (tick + 120) / 240 * 240;
        tick = std::min(tick, XTC_PROJECT_MAX_TICK);
        float min = mixer_.parameter() == XTC_AUTOMATION_GAIN ? 0.0f : -1.0f;
        float range = mixer_.parameter() == XTC_AUTOMATION_GAIN ? 4.0f : 2.0f;
        float value = min + static_cast<float>(std::clamp(y() + h() - 6 - Fl::event_y(), 0, h() - 28)) /
                                static_cast<float>(h() - 28) * range;
        if (Fl::event_button() == FL_RIGHT_MOUSE) {
            size_t count = 0;
            xtc_project_automation_count(mixer_.project(), &count);
            uint64_t distance = static_cast<uint64_t>(8) * lane_ticks / static_cast<uint64_t>(w() - 1) + 1,
                     closest = UINT64_MAX;
            for (size_t i = 0; i < count; ++i) {
                xtc_automation_point a{};
                xtc_project_get_automation(mixer_.project(), i, &a);
                uint64_t d = a.tick > tick ? a.tick - tick : tick - a.tick;
                if (a.track_id == mixer_.selected_track() && a.parameter == mixer_.parameter() && d < distance) {
                    distance = d;
                    closest = a.tick;
                }
            }
            if (closest != UINT64_MAX)
                mixer_.point(closest, 0, true);
        } else
            mixer_.point(tick, value);
        return 1;
    }
};

/**
 * @brief Creates the mixer panel and its child controls.
 *
 * Builds the track chooser, gain/pan sliders, mute/solo buttons, output
 * meters, automation controls, and lane, then displays the given project.
 *
 * @param x Left edge in parent coordinates.
 * @param y Top edge in parent coordinates.
 * @param w Widget width in pixels.
 * @param h Widget height in pixels.
 * @param p Project to display; borrowed and must outlive its use.
 * @param before Callback invoked before each edit; may be nullptr.
 * @param context Opaque pointer forwarded to before.
 */
MixerWidget::MixerWidget(int x, int y, int w, int h, xtc_project *p, BeforeEdit before, void *context)
    : Fl_Group(x, y, w, h), project_(p), before_(before), context_(context)
{
    begin();
    tracks_ = new Fl_Choice(x + 70, y + 8, 240, 26, "Track");
    tracks_->callback(select, this);
    gain_ = new Fl_Value_Slider(x + 70, y + 48, 320, 28, "Gain");
    gain_->type(FL_HOR_NICE_SLIDER);
    gain_->bounds(0, 4);
    gain_->step(0.01);
    gain_->when(FL_WHEN_RELEASE);
    gain_->callback(control, this);
    pan_ = new Fl_Value_Slider(x + 480, y + 48, 320, 28, "Pan");
    pan_->type(FL_HOR_NICE_SLIDER);
    pan_->bounds(-1, 1);
    pan_->step(0.01);
    pan_->when(FL_WHEN_RELEASE);
    pan_->callback(control, this);
    mute_ = new Fl_Check_Button(x + 340, y + 8, 90, 26, "Mute");
    solo_ = new Fl_Check_Button(x + 440, y + 8, 90, 26, "Solo");
    mute_->callback(control, this);
    solo_->callback(control, this);
    left_ = new Fl_Progress(x + 70, y + 90, 320, 20, "Output L");
    right_ = new Fl_Progress(x + 480, y + 90, 320, 20, "Output R");
    for (auto *meter : {left_, right_}) {
        meter->minimum(0);
        meter->maximum(1);
        meter->selection_color(fl_rgb_color(80, 180, 120));
    }
    parameter_ = new Fl_Choice(x + 110, y + 126, 150, 26, "Automation");
    parameter_->add("Gain|Pan");
    parameter_->value(0);
    parameter_->callback(select, this);
    start_ = new Fl_Value_Input(x + 420, y + 126, 140, 26, "First tick");
    start_->bounds(0, XTC_PROJECT_MAX_TICK - lane_ticks);
    start_->step(3840);
    start_->callback(select, this);
    auto *hint = new Fl_Box(x + 10, y + 160, w - 20, 24,
                            "Gain 0..4; pan -1 left / +1 right. M/S toggles; arrows change gain, "
                            "Shift+arrows pan; Up/Down selects track.");
    hint->labelsize(12);
    lane_ = new AutomationLane(x + 10, y + 192, w - 20, h - 222, *this);
    end();
    set_project(p);
}

/**
 * @brief Returns the ID of the track selected in the track chooser.
 *
 * @return Selected track ID, or UINT64_MAX when the chooser selection does
 *         not resolve to a project track.
 */
uint64_t MixerWidget::selected_track() const
{
    xtc_track_info t{};
    return xtc_project_get_track(project_, static_cast<size_t>(tracks_->value()), &t) == XTC_OK ? t.id : UINT64_MAX;
}

/**
 * @brief Returns the automation parameter selected in the chooser.
 *
 * @return XTC_AUTOMATION_PAN when the chooser selects "Pan", otherwise
 *         XTC_AUTOMATION_GAIN.
 */
xtc_automation_parameter MixerWidget::parameter() const
{
    return parameter_->value() == 1 ? XTC_AUTOMATION_PAN : XTC_AUTOMATION_GAIN;
}

/**
 * @brief Returns the first tick shown by the automation lane.
 *
 * @return Clamped first tick in project ticks, or 0 when the input value is
 *         not finite.
 */
uint64_t MixerWidget::lane_start() const
{
    if (!std::isfinite(start_->value()))
        return 0;
    return static_cast<uint64_t>(
        std::clamp(start_->value(), 0.0, static_cast<double>(XTC_PROJECT_MAX_TICK - lane_ticks)));
}

/**
 * @brief Displays a different project and refreshes the controls.
 *
 * The current track selection is preserved only when the same project
 * pointer is passed again. The project is borrowed and must outlive use.
 *
 * @param p Project to display; must remain valid while shown.
 */
void MixerWidget::set_project(xtc_project *p)
{
    uint64_t selected = project_ == p ? selected_track() : UINT64_MAX;
    project_ = p;
    tracks_->clear();
    size_t n = 0, c = 0;
    xtc_project_get_counts(p, &n, &c);
    int index = 0;
    for (size_t i = 0; i < n; ++i) {
        xtc_track_info t{};
        xtc_project_get_track(p, i, &t);
        std::string label;
        for (char ch : std::string(t.name)) {
            if (ch == '/' || ch == '\\' || ch == '_' || ch == '&')
                label += '\\';
            label += ch;
        }
        tracks_->add(label.c_str());
        if (t.id == selected)
            index = static_cast<int>(i);
    }
    tracks_->value(n ? index : -1);
    selection();
    redraw();
}

/**
 * @brief Synchronizes the child controls with the selected track.
 *
 * Controls are deactivated when no valid track is selected. Gain falls
 * back to 1, and the remaining values come from the track info or zero when
 * unresolved.
 */
void MixerWidget::selection()
{
    xtc_track_info t{};
    bool valid = xtc_project_get_track(project_, static_cast<size_t>(tracks_->value()), &t) == XTC_OK;
    for (Fl_Widget *w :
         {static_cast<Fl_Widget *>(gain_), static_cast<Fl_Widget *>(pan_), static_cast<Fl_Widget *>(mute_),
          static_cast<Fl_Widget *>(solo_), static_cast<Fl_Widget *>(lane_)}) {
        if (valid)
            w->activate();
        else
            w->deactivate();
    }
    gain_->value(valid ? t.gain : 1);
    pan_->value(t.pan);
    mute_->value(t.mute);
    solo_->value(t.solo);
    lane_->redraw();
}

/**
 * @brief Updates the left and right output meters.
 *
 * Meter values are clamped to 1.0, while the over-range color is chosen
 * from the unclamped level.
 *
 * @param left Left-channel peak level.
 * @param right Right-channel peak level.
 */
void MixerWidget::peaks(float left, float right)
{
    left_->value(std::min(left, 1.0f));
    right_->value(std::min(right, 1.0f));
    left_->selection_color(left > 1 ? FL_RED : FL_GREEN);
    right_->selection_color(right > 1 ? FL_RED : FL_GREEN);
}

/**
 * @brief Reports an edit result and refreshes the controls.
 *
 * A successful result invokes the widget callback so the owner can mark
 * the project dirty; a failure shows a modal alert. The controls are
 * resynchronized in both cases.
 *
 * @param r Result of the attempted edit.
 * @return The same result passed in.
 */
xtc_result MixerWidget::changed(xtc_result r)
{
    if (r == XTC_OK)
        do_callback();
    else
        fl_alert("Mixer edit failed: %s", xtc_result_string(r));
    selection();
    return r;
}

/**
 * @brief Applies gain, pan, mute, and solo to the selected track.
 *
 * The constructor's before-edit callback runs first; the edit is skipped
 * if it returns an error. On success the widget callback is invoked and
 * the controls are refreshed.
 *
 * @param gain Linear gain in the range 0..4.
 * @param pan Pan position in the range -1 (left)..1 (right).
 * @param mute Mute state: 0 or 1.
 * @param solo Solo state: 0 or 1.
 * @return XTC_OK on success, or the before-edit or project mutation error.
 */
xtc_result MixerWidget::mix(float gain, float pan, int mute, int solo)
{
    xtc_result r = before_ ? before_(context_) : XTC_OK;
    if (r == XTC_OK)
        r = xtc_project_set_mix(project_, selected_track(), gain, pan, mute, solo);
    return changed(r);
}

/**
 * @brief Adds, replaces, or removes an automation point.
 *
 * The constructor's before-edit callback runs first; the edit is skipped
 * if it returns an error. On success the widget callback is invoked and
 * the controls are refreshed.
 *
 * @param tick Automation tick to modify; must be within the project range.
 * @param value New value; ignored when remove is true.
 * @param remove When true, removes the point instead of setting it.
 * @return XTC_OK on success, or the before-edit or project mutation error.
 */
xtc_result MixerWidget::point(uint64_t tick, float value, bool remove)
{
    xtc_result r = before_ ? before_(context_) : XTC_OK;
    xtc_automation_point a{selected_track(), tick, parameter(), value};
    if (r == XTC_OK)
        r = remove ? xtc_project_remove_automation(project_, a.track_id, a.parameter, tick)
                   : xtc_project_set_automation(project_, &a);
    return changed(r);
}

/**
 * @brief FLTK callback for the gain, pan, mute, and solo controls.
 *
 * Reads all four controls and applies them together to the selected track
 * through mix().
 *
 * @param c Opaque MixerWidget pointer supplied as callback context.
 */
void MixerWidget::control(Fl_Widget *, void *c)
{
    auto *m = static_cast<MixerWidget *>(c);
    m->mix(static_cast<float>(m->gain_->value()), static_cast<float>(m->pan_->value()), m->mute_->value(),
           m->solo_->value());
}

/**
 * @brief FLTK callback for the track, parameter, and first-tick controls.
 *
 * @param c Opaque MixerWidget pointer supplied as callback context.
 */
void MixerWidget::select(Fl_Widget *, void *c)
{
    static_cast<MixerWidget *>(c)->selection();
}

/**
 * @brief Handles keyboard shortcuts and forwards other events.
 *
 * M and S toggle mute and solo, Left/Right adjust gain (Shift adjusts pan),
 * and Up/Down change the selected track. Modified key presses fall through.
 *
 * @param e FLTK event code.
 * @return 1 when the event was consumed, otherwise the Fl_Group result.
 */
int MixerWidget::handle(int e)
{
    if (e == FL_KEYDOWN && !(Fl::event_state() & (FL_CTRL | FL_ALT | FL_META))) {
        int key = Fl::event_key();
        xtc_track_info t{};
        if (xtc_project_get_track(project_, static_cast<size_t>(tracks_->value()), &t) == XTC_OK) {
            if (key == 'm' || key == 's') {
                mix(t.gain, t.pan, key == 'm' ? !t.mute : t.mute, key == 's' ? !t.solo : t.solo);
                return 1;
            }
            if (key == FL_Left || key == FL_Right) {
                float d = key == FL_Left ? -0.05f : 0.05f;
                bool pan = (Fl::event_state() & FL_SHIFT) != 0;
                mix(pan ? t.gain : std::clamp(t.gain + d, 0.0f, 4.0f), pan ? std::clamp(t.pan + d, -1.0f, 1.0f) : t.pan,
                    t.mute, t.solo);
                return 1;
            }
            if (key == FL_Up || key == FL_Down) {
                size_t n = 0, c = 0;
                xtc_project_get_counts(project_, &n, &c);
                tracks_->value(std::clamp(tracks_->value() + (key == FL_Up ? -1 : 1), 0, static_cast<int>(n) - 1));
                selection();
                return 1;
            }
        }
    }
    return Fl_Group::handle(e);
}