#ifndef XTC_MIXER_WIDGET_HPP
#define XTC_MIXER_WIDGET_HPP
#include "xtc/xtc_mixer.h"
#include "xtc/xtc_backend.h"
#include <FL/Fl_Group.H>
#include <chrono>
#include <vector>

class Fl_Choice;
class Fl_Button;
class Fl_Value_Slider;
class Fl_Check_Button;
class Fl_Progress;
class Fl_Value_Input;
class AutomationLane;
class MixerStrip;
class Fl_Scroll;
class Fl_Box;

class MixerWidget : public Fl_Group {
  public:
    /**
     * @brief Prepares a model edit using the widget's opaque callback context.
     *
     * @return XTC_OK to allow the edit, or an error to cancel it.
     */
    using BeforeEdit = xtc_result (*)(void *);

    /**
     * @brief Creates the mixer panel and its child controls.
     *
     * Builds the track chooser, channel strips, pan knobs, 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(int x, int y, int w, int h, xtc_project * p, BeforeEdit before, void * context);

    /**
     * @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 set_project(xtc_project * p);

    /**
     * @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 peaks(float left, float right);

    /**
     * @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 selected_track() const;

    /**
     * @brief Returns the project currently displayed by the widget.
     *
     * @return Borrowed project pointer, possibly nullptr; the widget does not
     *         own it.
     */
    xtc_project *project() const
    {
        return project_;
    }

    /**
     * @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 parameter() const;

    /**
     * @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 lane_start() const;

    /**
     * @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 point(uint64_t tick, float value, bool remove = false);

    /**
     * @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 add_bus();
    xtc_result route(uint64_t bus);
    bool select_track(uint64_t id);
    void track_peaks(float left, float right);
    /* One control-thread snapshot updates all strips; missing taps decay to silence. */
    void meters(const xtc_meter_snapshot &snapshot);
    Fl_Group *strip(uint64_t id) const;
    size_t strip_count() const { return strips_.size(); }
    void resize(int x, int y, int w, int h) override;
    void reset_meters();
    bool master_clipped() const { return master_[0].clipped || master_[1].clipped; }
    xtc_result mix(float gain, float pan, int mute, int solo);

    /**
     * @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 event FLTK event code.
     * @return 1 when the event was consumed, otherwise the Fl_Group result.
     */
    int handle(int event) override;

  private:
    xtc_project *project_;
    BeforeEdit before_;
    void *context_;
    Fl_Choice *tracks_, *parameter_, *routes_, *mode_;
    std::vector<uint64_t> route_ids_;
    Fl_Progress *left_, *right_;
    Fl_Scroll *bank_;
    Fl_Group *master_panel_;
    Fl_Button *bus_, *reset_;
    Fl_Box *hint_, *master_readout_;
    std::vector<MixerStrip *> strips_;
    void sync_strips(bool reset = false);
    void layout();
    xtc_peak_meter master_[2]{};
    uint64_t selected_id_ = UINT64_MAX;
    std::chrono::steady_clock::time_point peak_time_ = std::chrono::steady_clock::now();
    double meter_elapsed_ = 0.1;
    void display_peaks(Fl_Progress *left, Fl_Progress *right, xtc_peak_meter *meters, const char *prefix);

    Fl_Value_Input *start_;
    AutomationLane *lane_;
    /**
     * @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 changed(xtc_result r);

    /**
     * @brief Synchronizes the child controls with the selected track.
     *
     * Reconcile strip controls with stable model IDs and the selected
     * automation target.
     */
    void selection();

    /**
     * @brief FLTK callback for the track, parameter, and first-tick controls.
     *
     * @param widget Track chooser or automation control that changed.
     * @param c Opaque MixerWidget pointer supplied as callback context.
     */
    static void select(Fl_Widget * widget, void * c);
};
#endif