import { render } from './render.js';


const X_START = '0.7t+sin(t)-6';
const Y_START = '0.7t-6';

const PATH_LEN = 20;
const PATH_STEP = PATH_LEN/1000;

const SLOW_RAMP = 1;
const FAST_RAMP = 0.01;


export function setupLevel(resources, home) {
  const level = {
    resources: resources.map(position => ({ position, collected: false })),
    home,
    running: false,
    completed: false,
    index: 0,
    equations: {
      x: math.compile(X_START),
      y: math.compile(Y_START),
    },
  };
  level.path = computePath(level.equations);
  return level;
}


export function setupLevelUi(level, root, audio) {
  const ui = { audio };

  ui.resourceAudio = document.getElementById('sfx-resource');
  ui.resourceSource = audio.createMediaElementSource(ui.resourceAudio);
  ui.resourceSource.connect(audio.destination);

  ui.doneAudio = document.getElementById('sfx-done');
  ui.doneSource = audio.createMediaElementSource(ui.doneAudio);
  ui.doneSource.connect(audio.destination);

  ui.wrongAudio = document.getElementById('sfx-wrong');
  ui.wrongSource = audio.createMediaElementSource(ui.wrongAudio);
  ui.wrongSource.connect(audio.destination);

  ui.launchButton = document.createElement('input');
  ui.launchButton.type = 'button';
  ui.launchButton.value = 'Launch';
  ui.launchButton.onclick = () => {
    ui.message.innerText = '';
    level.running = false;
    setTimeout(() => { level.running=true; stepLevel(ui, level, 0); }, 20);
  }

  ui.xeq = document.createElement('input');
  ui.xeq.value = X_START;
  ui.xeq.onchange = (e) => {
    try {
      level.equations.x = math.compile(e.target.value);
    } catch(err) { }
    level.running = false;
    level.path = computePath(level.equations);
    render(ui.ctx, level, 0);
  };
  ui.xeq.onkeydown = ui.xeq.onchange;
  ui.xeq.onkeyup = ui.xeq.onchange;

  ui.yeq = document.createElement('input');
  ui.yeq.value = Y_START;
  ui.yeq.onchange = (e) => {
    try {
      level.equations.y = math.compile(e.target.value);
    } catch(err) { }
    level.running = false;
    level.path = computePath(level.equations);
    render(ui.ctx, level, 0);
  };
  ui.yeq.onkeydown = ui.yeq.onchange;
  ui.yeq.onkeyup = ui.yeq.onchange;

  ui.message = document.createElement('div');
  ui.id = "level-message";

  root.appendChild(ui.launchButton);
  root.appendChild(ui.xeq);
  root.appendChild(ui.yeq);
  root.appendChild(ui.message);

  ui.canvas = document.createElement('canvas');
  ui.canvas.width = 600;
  ui.canvas.height = 600;
  root.appendChild(ui.canvas);

  ui.ctx = ui.canvas.getContext('2d');
  ui.ctx.translate(ui.canvas.width/2, ui.canvas.height/2)
  ui.ctx.scale(ui.canvas.width/20, -ui.canvas.height/20);

  render(ui.ctx, level, 0);
  return ui;
}


function stepLevel(ui, level, index) {
  render(ui.ctx, level, index);

  const pos = level.path[index];
  const distances = level.resources
    .map((x, i) => [x, i])
    .filter(([x, _]) => x.collected === false)
    .map(([x, i]) => [ distance(pos, x.position), i ])
    .forEach(([d, i]) => {
      if (d < 0.4) { 
        ui.resourceAudio.load();
        ui.resourceAudio.play();
        level.resources[i].collected = true; 
      }
    });



  if (distance(pos, level.home) < 0.4) {
    level.running = false;
    finishLevel(ui, level);
    render(ui.ctx, level, 0);
  } else if (level.running && index < level.path.length-1) {
    setTimeout(() => stepLevel(ui, level, index+1), 1);
  } else {
    level.running = false;
    render(ui.ctx, level, 0);
  }
}


function computePath(equations, start, end, step) {
  try {
    const ts = [...Array(Math.floor((PATH_LEN)/PATH_STEP)).keys()].map(k => PATH_STEP * k);
    return ts.map(t => [ equations.x.eval({t}), equations.y.eval({t}) ]);
  } catch (err) {
    return [ [0, 0] ];
  }
}


function distance(p1, p2) {
  const [x1, y1] = p1;
  const [x2, y2] = p2;
  return Math.sqrt((x2-x1)**2 + (y2-y1)**2);
}


function finishLevel(ui, level) {
  const uncollected = level.resources.reduce((acc, { collected }) => acc + (collected ? 0 : 1), 0);
  if (uncollected > 0) {
    ui.wrongAudio.load();
    ui.wrongAudio.play();
    ui.message.innerText = 'resources remaining!';
  } else {
    ui.doneAudio.load();
    ui.doneAudio.play();
    ui.message.innerText = 'mission complete!';
    level.completed = true;
  }
  level.resources.forEach(x => x.collected = false);
}