#include "Grid.hpp"
#include <libscscreensaver.hpp>
#include <libscnumerics.hpp>
#include <vector>
#include <cmath>
#include <string>

const std::string black {"#000000"};
const std::string white {"#FFFFFF"};
const std::string sand {"#B69061"};
const std::string pastel_green {"#B1D1AF"};

struct Rect {
    double cx {0};
    double cy {0};
    double width {0};
    Color color {black};
};

struct Situation {
    std::vector<Rect> rects;
    Color bg {pastel_green};
};

enum class State {wait, fade};

class Grid : public ScreensaverPlugin {
    public:
        Grid() = default;
        ~Grid() = default;

        void setup(cairo_t* context, const cairo_rectangle_t& rect) override;
        void configure() override;
        int fps() const override;
        void update() override;
        void render() override;

    private:
        size_t _h;
        size_t _v;
        Situation _old;
        Situation _new;
        Situation _cur;
        std::vector<Color> _colors;
        int _frames {0};
        State _s {State::fade};
        double _d {75}; // grid point distance
        int _wait {7}; // seconds
        int _fade {3}; // seconds
        double _border {75};
        double _min_size {2};
        double _max_size {50};
        bool _change_bg {true};
        void animate();
};

ScreensaverPlugin* create_instance() {
    return new Grid;
}

void Grid::setup(cairo_t* context, const cairo_rectangle_t& rect) {
    ScreensaverPlugin::setup(context, rect);
    if (_colors.size() == 0) {
        _colors.emplace_back(black);
        _colors.emplace_back(white);
        _colors.emplace_back(sand);
    }
    _old.rects.clear();
    _old.bg = black;
    _new.rects.clear();
    _cur.rects.clear();
    cairo_rectangle_t inset {rect};
    inset.width -= 2 * _border;
    inset.height -= 2 * _border;
    _h = static_cast<size_t>(round(inset.width / _d));
    _v = static_cast<size_t>(round(inset.height / _d));
    double h_margin = (inset.width - (_h - 1) * _d) / 2;
    double v_margin = (inset.height - (_v - 1) * _d) / 2;
    for (size_t x = 0; x < _h; ++x) {
        for (size_t y = 0; y < _v; ++y) {
            Rect r;
            r.cx = _border + h_margin + x * _d;
            r.cy = _border + v_margin + y * _d;
            r.width = 0;
            r.color = black;
            _old.rects.push_back(r);
            _cur.rects.push_back(r);
            r.width = random_between(_min_size, _max_size);
            r.color = sc::random::choice(_colors);
            _new.rects.push_back(r);
        }
    }
}

void Grid::configure() {
    _min_size = _j["min-size"];
    _max_size = _j["max-size"];
    _d = _j["dist"];
    _wait = _j["wait"];
    _fade = _j["fade"];
    _border = _j["border"];
    _new.bg = Color {_j["bg"]};
    _change_bg = _j["changebg"];
    _colors.clear();
    for (const auto& hex : _j["colors"]) {
        _colors.emplace_back(hex);
    }
    setup(_c, _r);
}

int Grid::fps() const {
    return 30;
}

void Grid::update() {
    // adjust state for next render
    switch (_s) {
        case State::wait:
            if (++_frames > _wait * fps()) {
                _frames = 0;
                _s = State::fade;
            }
            break;
        case State::fade:
            if (++_frames > _fade * fps()) {
                _frames = 0;
                _old = _new;
                for (Rect& r : _new.rects) {
                    r.width = random_between(_min_size, _max_size);
                    r.color = sc::random::choice(_colors);
                }
                HSB newbg {random_between(0, 360), 0.16, 0.82};
                _new.bg = newbg;
                _s = State::wait;
            } else {
                animate();
            }
            break;
    }
}

void Grid::render() {
    // render one frame based on current state
    if (_s == State::fade) {
        RGB bg {RGB(_cur.bg)};
        cairo_set_source_rgb(_c, bg.r, bg.g, bg.b);
        cairo_rectangle(_c, _r.x, _r.y, _r.width, _r.height);
        cairo_fill(_c);
        for (const Rect& r : _cur.rects) {
            RGB col {RGB(r.color)};
            cairo_set_source_rgb(_c, col.r, col.g, col.b);
            cairo_rectangle(_c, r.cx - r.width / 2, r.cy - r.width / 2, r.width, r.width);
            cairo_fill(_c);
        }
    }
}

void Grid::animate() {
    double f {static_cast<double>(_frames) / (_fade * fps())};
    if (_change_bg) {
        RGB bg1 {RGB(_old.bg)};
        RGB bg2 {RGB(_new.bg)};
        RGB bg3 {bg1.r + f * (bg2.r - bg1.r), bg1.g + f * (bg2.g - bg1.g), bg1.b + f * (bg2.b - bg1.b)};
        _cur.bg = bg3;
    }
    for (size_t i = 0; i < _old.rects.size(); ++i) {
        Rect& r1 = _old.rects[i];
        Rect& r2 = _new.rects[i];
        Rect& r3 = _cur.rects[i];
        RGB rgb1 {RGB(r1.color)};
        RGB rgb2 {RGB(r2.color)};
        RGB rgb3 {rgb1.r + f * (rgb2.r - rgb1.r), rgb1.g + f * (rgb2.g - rgb1.g), rgb1.b + f * (rgb2.b - rgb1.b)};
        r3.color = rgb3;
        r3.width = r1.width + f * (r2.width - r1.width);
    }
}