// Opengl
#include <glad/glad.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/matrix_access.hpp>
#include <glm/gtx/vector_angle.hpp>

#include "imgui.h"
#include "ImGuiToolkit.h"

#include <string>
#include <sstream>

#include "Mixer.h"
#include "defines.h"
#include "Settings.h"
#include "SessionSource.h"
#include "DrawVisitor.h"
#include "Decorations.h"
#include "UserInterfaceManager.h"
#include "Log.h"

#include "TransitionView.h"


TransitionView::TransitionView() : View(TRANSITION), transition_source_(nullptr)
{
    // read default settings
    if ( Settings::application.views[mode_].name.empty() )
    {
        // no settings found: store application default
        Settings::application.views[mode_].name = "Transition";
        scene.root()->scale_ = glm::vec3(TRANSITION_DEFAULT_SCALE, TRANSITION_DEFAULT_SCALE, 1.0f);
        scene.root()->translation_ = glm::vec3(1.5f, 0.f, 0.0f);
        saveSettings();
    }
    else
        restoreSettings();

    // Geometry Scene background
    gradient_ = new Switch;
    gradient_->attach(new ImageSurface("images/gradient_0_cross_linear.png"));
    gradient_->attach(new ImageSurface("images/gradient_1_black_linear.png"));
    gradient_->attach(new ImageSurface("images/gradient_2_cross_quad.png"));
    gradient_->attach(new ImageSurface("images/gradient_3_black_quad.png"));
    gradient_->scale_ = glm::vec3(0.501f, 0.006f, 1.f);
    gradient_->translation_ = glm::vec3(-0.5f, -0.005f, -0.01f);
    scene.fg()->attach(gradient_);

    mark_1s_ = new Mesh("mesh/h_mark.ply");
    mark_1s_->translation_ = glm::vec3(-1.f, -0.01f, 0.0f);
    mark_1s_->shader()->color = glm::vec4( COLOR_TRANSITION_LINES, 0.9f );
    scene.fg()->attach(mark_1s_);

    mark_100ms_ = new Mesh("mesh/h_mark.ply");
    mark_100ms_->translation_ = glm::vec3(-1.f, -0.01f, 0.0f);
    mark_100ms_->scale_ = glm::vec3(0.5f, 0.5f, 0.0f);
    mark_100ms_->shader()->color = glm::vec4( COLOR_TRANSITION_LINES, 0.9f );
    scene.fg()->attach(mark_100ms_);

    // move the whole forground below the icons
    scene.fg()->translation_ = glm::vec3(0.f, -0.11f, 0.0f);

    output_surface_ = new Surface;
    scene.bg()->attach(output_surface_);

    Frame *border = new Frame(Frame::ROUND, Frame::THIN, Frame::GLOW);
    border->color = glm::vec4( COLOR_FRAME, 1.0f );
    scene.bg()->attach(border);

    scene.bg()->scale_ = glm::vec3(0.1f, 0.1f, 1.f);
    scene.bg()->translation_ = glm::vec3(0.4f, 0.f, 0.0f);

}

void TransitionView::update(float dt)
{
    // update scene
    View::update(dt);

    // a more complete update is requested
    if  (View::need_deep_update_ > 0) {

        // update rendering of render frame
        FrameBuffer *output = Mixer::manager().session()->frame();
        if (output){
            float aspect_ratio = output->aspectRatio();
            for (NodeSet::iterator node = scene.bg()->begin(); node != scene.bg()->end(); node++) {
                (*node)->scale_.x = aspect_ratio;
            }
            output_surface_->setTextureIndex( output->texture() );
        }

    }

    // Update transition source
    if ( transition_source_ != nullptr) {

        float d = transition_source_->group(View::TRANSITION)->translation_.x;

        // Transfer this movement to changes in mixing
        // cross fading
        if ( Settings::application.transition.cross_fade )
        {
            float f = 0.f;
            // change alpha of session:
            if (Settings::application.transition.profile == 0)
                // linear => identical coordinates in Mixing View
                f = d;
            else {
                // quadratic => square coordinates in Mixing View
                f = (d+1.f)*(d+1.f) -1.f;
            }
            transition_source_->group(View::MIXING)->translation_.x = CLAMP(f, -1.f, 0.f);
            transition_source_->group(View::MIXING)->translation_.y = 0.f;

        }
        // fade to black
        else
        {
            // change alpha of session ; hidden before -0.5, visible after
            transition_source_->group(View::MIXING)->translation_.x = d < -0.5f ? -1.f : 0.f;
            transition_source_->group(View::MIXING)->translation_.y = 0.f;

            // fade to black at 50% : fade-out [-1.0 -0.5], fade-in [-0.5 0.0]
            float f = 0.f;
            if (Settings::application.transition.profile == 0)
                f = ABS(2.f * d + 1.f);  // linear
            else {
                f = ( 2.f * d + 1.f);  // quadratic
                f *= f;
            }
            Mixer::manager().session()->setFading( 1.f - f );
        }

        // request update
        transition_source_->touch();

        if (d > 0.2f && Settings::application.transition.auto_open)
            Mixer::manager().setView(View::MIXING);

    }


}


void TransitionView::draw()
{
    // update the GUI depending on changes in settings
    gradient_->setActive( 2*Settings::application.transition.profile + (Settings::application.transition.cross_fade ? 0 : 1) );

    // draw scene of this view
    View::draw();

    // 100ms tic marks
    int n = static_cast<int>( Settings::application.transition.duration / 0.1f );
    glm::mat4 T = glm::translate(glm::identity<glm::mat4>(), glm::vec3( 1.f / n, 0.f, 0.f));
    DrawVisitor dv(mark_100ms_, Rendering::manager().Projection());
    dv.loop(n+1, T);
    scene.accept(dv);

    // 1s tic marks
    int N = static_cast<int>( Settings::application.transition.duration );
    T = glm::translate(glm::identity<glm::mat4>(), glm::vec3( 10.f / n, 0.f, 0.f));
    DrawVisitor dv2(mark_1s_, Rendering::manager().Projection());
    dv2.loop(N+1, T);
    scene.accept(dv2);

    // display interface duration
    glm::vec2 P = Rendering::manager().project(glm::vec3(-0.17f, -0.14f, 0.f), scene.root()->transform_, false);
    ImGui::SetNextWindowPos(ImVec2(P.x, P.y), ImGuiCond_Always);
    if (ImGui::Begin("##Transition", NULL, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoDecoration | ImGuiWindowFlags_NoBackground
                     | ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_NoSavedSettings
                     | ImGuiWindowFlags_NoFocusOnAppearing | ImGuiWindowFlags_NoBringToFrontOnFocus))
    {

        // style grey
        ImGui::PushStyleColor(ImGuiCol_FrameBg, ImVec4(0.27f, 0.27f, 0.27f, 0.55f));
        ImGui::PushStyleColor(ImGuiCol_FrameBgHovered, ImVec4(0.27f, 0.27f, 0.27f, 0.79f));
        ImGui::PushStyleColor(ImGuiCol_FrameBgActive, ImVec4(0.27f, 0.27f, 0.27f, 0.7f));
        ImGui::PushStyleColor(ImGuiCol_SliderGrab, ImVec4(0.15f, 0.15f, 0.15f, 1.00f));
        ImGui::PushStyleColor(ImGuiCol_SliderGrabActive, ImVec4(0.10f, 0.10f, 0.10f, 1.00f));
        ImGui::PushStyleColor(ImGuiCol_Button, ImVec4(0.00f, 0.00f, 0.00f, 0.00f));
        ImGui::PushStyleColor(ImGuiCol_ButtonHovered, ImVec4(0.27f, 0.27f, 0.27f, 0.55f)); // 7 colors

        ImGuiToolkit::PushFont(ImGuiToolkit::FONT_LARGE);
        ImGui::SetNextItemWidth(180.f);
        ImGui::SliderFloat("##transitionduration", &Settings::application.transition.duration,
                           TRANSITION_MIN_DURATION, TRANSITION_MAX_DURATION, "%.1f s");
        ImGui::SameLine();
        if ( ImGui::Button(ICON_FA_STEP_FORWARD) )
            play(false);

        ImGui::PopFont();
        ImGui::PopStyleColor(7);  // 7 colors
        ImGui::End();
    }

    P = Rendering::manager().project(glm::vec3(-0.535f, -0.14f, 0.f), scene.root()->transform_, false);
    ImGui::SetNextWindowPos(ImVec2(P.x, P.y), ImGuiCond_Always);
    if (ImGui::Begin("##TransitionType", NULL, ImGuiWindowFlags_NoMove | ImGuiWindowFlags_NoDecoration | ImGuiWindowFlags_NoBackground
                     | ImGuiWindowFlags_AlwaysAutoResize | ImGuiWindowFlags_NoSavedSettings
                     | ImGuiWindowFlags_NoFocusOnAppearing | ImGuiWindowFlags_NoBringToFrontOnFocus))
    {
        ImGuiToolkit::PushFont(ImGuiToolkit::FONT_LARGE);

        // black background in icon 'transition to black'
        if (!Settings::application.transition.cross_fade) {
            ImVec2 draw_pos = ImGui::GetCursorScreenPos();
            ImGui::PushStyleColor(ImGuiCol_Text, ImVec4(0.0f, 0.0f, 0.0f, 1.f));
            ImGuiToolkit::Icon(19,1);
            ImGui::PopStyleColor();
            ImGui::SetCursorScreenPos(draw_pos);
        }

        // toggle transition mode
        const char *tooltip[2] = {"Transition to black", "Cross fading"};
        ImGuiToolkit::IconToggle(0,2,0,8, &Settings::application.transition.cross_fade, tooltip );

        ImGui::PopFont();
        ImGui::End();
    }

}

bool TransitionView::canSelect(Source *s) {

    return ( s!=nullptr && s == transition_source_);
}

void TransitionView::attach(SessionFileSource *ts)
{
    // store source for later (detatch & interaction)
    transition_source_ = ts;

    if ( transition_source_ != nullptr) {
        // insert in scene
        Group *tg = transition_source_->group(View::TRANSITION);
        tg->visible_ = true;
        scene.ws()->attach(tg);

        // in fade to black transition, start transition from current fading value
        if ( !Settings::application.transition.cross_fade) {

            // reverse calculate x position to match actual fading of session
            float d = 0.f;
            if (Settings::application.transition.profile == 0)
                d = -1.f + 0.5f * Mixer::manager().session()->fading();  // linear
            else {
                d = -1.f - 0.5f * ( sqrt(1.f - Mixer::manager().session()->fading()) - 1.f);  // quadratic
            }

            transition_source_->group(View::TRANSITION)->translation_.x = d;
        }
    }
}

Session *TransitionView::detach()
{
    // by default, nothing to return
    Session *ret = nullptr;

    if ( transition_source_ != nullptr) {

        // get and detatch the group node from the view workspace
        Group *tg = transition_source_->group(View::TRANSITION);
        scene.ws()->detach( tg );


        // test if the icon of the transition source is "Ready"
        if ( tg->translation_.x > 0.f )
            // detatch the session and return it
            ret = transition_source_->detach();
        else
            // not detached: make current
            Mixer::manager().setCurrentSource(transition_source_);

        // done with transition
        transition_source_ = nullptr;
    }

    return ret;
}

void TransitionView::zoom (float factor)
{
    if (transition_source_ != nullptr) {
        float d = transition_source_->group(View::TRANSITION)->translation_.x;
        d += 0.1f * factor;
        transition_source_->group(View::TRANSITION)->translation_.x = CLAMP(d, -1.f, 0.f);
    }
}

std::pair<Node *, glm::vec2> TransitionView::pick(glm::vec2 P)
{
    std::pair<Node *, glm::vec2> pick = View::pick(P);

    if (transition_source_ != nullptr) {
        // start animation when clic on target
        if (pick.first == output_surface_)
            play(true);
        // otherwise cancel animation
        else
            transition_source_->group(View::TRANSITION)->clearCallbacks();
    }

    return pick;
}


void TransitionView::play(bool open)
{
    if (transition_source_ != nullptr) {

        // toggle play/stop with button
        if (!transition_source_->group(View::TRANSITION)->update_callbacks_.empty() && !open) {
            // just cancel previous animation
            transition_source_->group(View::TRANSITION)->clearCallbacks();
            return;
        }
        // else cancel previous animation and start new one
        transition_source_->group(View::TRANSITION)->clearCallbacks();

        // if want to open session after play, target  movement till end position, otherwise stop at 0
        float target_x = open ? 0.4f : 0.f;

        // calculate how far to reach target
        float time = CLAMP(- transition_source_->group(View::TRANSITION)->translation_.x, 0.f, 1.f);
        // extra distance to reach transition if want to open
        time += open ? 0.2f : 0.f;
        // calculate remaining time on the total duration, in ms
        time *= Settings::application.transition.duration  * 1000.f;


        // if remaining time is more than 50ms
        if (time > 50.f) {
            // start animation
            MoveToCallback *anim = new MoveToCallback(glm::vec3(target_x, 0.0, 0.0), time);
            transition_source_->group(View::TRANSITION)->update_callbacks_.push_back(anim);
        }
        // otherwise finish animation
        else
            transition_source_->group(View::TRANSITION)->translation_.x = target_x;
    }
}

View::Cursor TransitionView::grab (Source *s, glm::vec2 from, glm::vec2 to, std::pair<Node *, glm::vec2>)
{
    if (!s)
        return Cursor();

    // unproject
    glm::vec3 gl_Position_from = Rendering::manager().unProject(from, scene.root()->transform_);
    glm::vec3 gl_Position_to   = Rendering::manager().unProject(to, scene.root()->transform_);

    // compute delta translation
    float d = s->stored_status_->translation_.x + gl_Position_to.x - gl_Position_from.x;
    std::ostringstream info;
    if (d > 0.2) {
        s->group(mode_)->translation_.x = 0.4;
        info << "Open session";
    }
    else {
        s->group(mode_)->translation_.x = CLAMP(d, -1.f, 0.f);
        info << "Transition " <<  int( 100.f * (1.f + s->group(View::TRANSITION)->translation_.x)) << "%";
    }

    return Cursor(Cursor_ResizeEW, info.str() );
}

void TransitionView::arrow (glm::vec2 movement)
{
    Source *s = Mixer::manager().currentSource();
    if (s) {

        glm::vec3 gl_Position_from = Rendering::manager().unProject(glm::vec2(0.f), scene.root()->transform_);
        glm::vec3 gl_Position_to   = Rendering::manager().unProject(movement, scene.root()->transform_);
        glm::vec3 gl_delta = gl_Position_to - gl_Position_from;

        float d = s->group(mode_)->translation_.x + gl_delta.x * ARROWS_MOVEMENT_FACTOR;
        s->group(mode_)->translation_.x = CLAMP(d, -1.f, 0.f);

        // request update
        s->touch();
    }
}

View::Cursor TransitionView::drag (glm::vec2 from, glm::vec2 to)
{
    Cursor ret = View::drag(from, to);

    // Clamp translation to acceptable area
    scene.root()->translation_ = glm::clamp(scene.root()->translation_, glm::vec3(1.f, -1.7f, 0.f), glm::vec3(2.f, 1.7f, 0.f));

    return ret;
}