#include "sfml/components.hpp"
#include "sfml/sound.hpp"
#include "sfml/shaders.hpp"
#include "sfml/textures.hpp"
#include "guecs.hpp"
#include "constants.hpp"
#include <fmt/xchar.h>

#define FSM_DEBUG 1
#include "fsm.hpp"

constexpr const int WINDOW_WIDTH=300;
constexpr const int WINDOW_HEIGHT=400;

using std::string, std::wstring;

const std::unordered_map<string, wstring> LABELS {
    {"readout", L""}, {"clear", L"CLR"}, {"btn0", L"0"}, {"btn1", L"1"},
    {"btn2", L"2"}, {"btn3", L"3"}, {"btn4", L"4"},
    {"btn5", L"5"}, {"btn6", L"6"}, {"btn7", L"7"},
    {"btn8", L"8"}, {"btn9", L"9"}, {"mult", L"*"},
    {"minus", L"-"}, {"plus", L"+"}, {"neg", L"±"},
    {"div", L"/"}, {"eq", L"="} };

enum class Event {
  NUMBER, ADD, SUB, MUL,
  DIV, CLR, NOT, EQ,
};

enum class State {
  START,
  CALCULATING,
  CLEARED,
  DISPLAYED
};


struct Calculator : DeadSimpleFSM<State, Event> {
  wstring input;
  double value = 0.0;

  void event(Event ev, wchar_t op) {
    switch($state) {
      FSM_STATE(State, START, ev, op);
      FSM_STATE(State, CALCULATING, ev, op);
      FSM_STATE(State, CLEARED, ev, op);
      FSM_STATE(State, DISPLAYED, ev, op);
    }
  }

  void START(Event ev, wchar_t op) {
    if(ev == Event::NUMBER) {
      input += op;
      state(State::CALCULATING);
    }
  }

  void CALCULATING(Event ev, wchar_t op) {
    using enum Event;

    switch(ev) {
      case NUMBER:
        input += op;
        break;
      case ADD:
        value += std::stof(input);
        input = L"";
        break;
      case SUB:
        value -= std::stof(input);
        input = L"";
        break;
      case MUL:
        value *= std::stof(input);
        input = L"";
        break;
      case DIV:
        value /= std::stof(input);
        input = L"";
        break;
      case NOT:
        value = std::stof(input) * -1;
        input = L"";
        break;
      case EQ:
        value = std::stof(input);
        break;
      case CLR:
        input = L"";
        state(State::CLEARED);
        break;
    }
  }

  void CLEARED(Event ev, wchar_t op) {
    if(ev == Event::NUMBER) {
      input += op;
      state(State::CALCULATING);
    }
  }

  void DISPLAYED(Event ev, wchar_t op) {
    fmt::println(L"ev={}, op={}", (int)ev, op);
    state(State::CALCULATING);
  }
};

struct CalculatorUI {
  guecs::UI $gui;
  Calculator $fsm;

  CalculatorUI() {
    $gui.position(0, 0, WINDOW_WIDTH, WINDOW_HEIGHT);
    $gui.layout(
        "[*%(400)readout|_|_|_|clear]"
        "[btn7|btn8|btn9|mult]"
        "[btn4|btn5|btn6|minus]"
        "[btn1|btn2|btn3|plus]"
        "[neg|btn0|eq|div]");
  }

  void init() {
    $gui.set<guecs::Background>($gui.MAIN, {});

    for(auto& [name, cell] : $gui.cells()) {
      auto id = $gui.entity(name);
      auto& label = LABELS.at(name);

      $gui.set<guecs::Rectangle>(id, {});
      $gui.set<guecs::Effect>(id, {});

      if(name == "readout") {
        $gui.set<guecs::Textual>(id, {L"", 40});
      } else {
        $gui.set<guecs::Label>(id, { label });
        $gui.set<guecs::Clickable>(id, {
            [&, name](auto, auto) { handle_button(label[0]); }
        });
      }
    }

    $gui.init();
  }

  void render(sf::RenderWindow& window) {
    $gui.render(window);
    // $gui.debug_layout(window);
  }

  void mouse(float x, float y, bool hover) {
    $gui.mouse(x, y, hover);
  }

  void handle_button(wchar_t op) {
    using enum Event;

    switch(op) {
      case L'0':
      case L'1':
      case L'2':
      case L'3':
      case L'4':
      case L'5':
      case L'6':
      case L'7':
      case L'8':
      case L'9':
        $fsm.event(NUMBER, op);
        break;
      case L'*':
        $fsm.event(MUL, op);
        break;
      case L'-':
        $fsm.event(SUB, op);
        break;
      case L'+':
        $fsm.event(ADD, op);
        break;
      case L'/':
        $fsm.event(DIV, op);
        break;
      case L'±':
        $fsm.event(NOT, op);
        break;
      case L'=':
        $fsm.event(EQ, op);
        break;
      case L'C':
        $fsm.event(CLR, op);
        break;
    }

    auto readout = $gui.entity("readout");
    auto& label = $gui.get<guecs::Textual>(readout);
    label.update($fsm.input);
  }
};



int main() {
  sound::init();
  shaders::init();
  textures::init();

  sf::RenderWindow window(sf::VideoMode({WINDOW_WIDTH, WINDOW_HEIGHT}), "LEL-GUECS Calculator");
  window.setFramerateLimit(FRAME_LIMIT);
  window.setVerticalSyncEnabled(VSYNC);

  CalculatorUI calc;
  calc.init();

  while(window.isOpen()) {
    while (const auto event = window.pollEvent()) {
      if(event->is<sf::Event::Closed>()) {
        window.close();
      }

      if(const auto* mouse = event->getIf<sf::Event::MouseButtonPressed>()) {
        if(mouse->button == sf::Mouse::Button::Left) {
          sf::Vector2f pos = window.mapPixelToCoords(mouse->position);
          calc.mouse(pos.x, pos.y, false);
        }
      }
    }

    calc.render(window);
    window.display();
  }
}