"use strict";
import {interpret} from "./interpreter.js";

(function () {
    const command_input_element = document.getElementById('command_input');
    const canvas_element = document.getElementById('canvas');
    const canvas = canvas_element.getContext('2d');
    const width = window.innerWidth;
    const height = window.innerHeight;
    canvas.clearRect(0, 0, width, height);
    canvas.lineWidth = 2;
    canvas.globalAlpha = 1;
    canvas.strokeStyle = 'black';
    canvas.fillStyle = 'black';
    canvas_element.width = width;
    canvas_element.height = height;

    const help_element = document.getElementById('help');
    let script;
    let tx = 0;
    let ty = 0;
    let tangle = 0;

    document.body.onkeydown = function (event) {
      if (event.key === 'Tab') {
        event.preventDefault();
      }
    }

    const count = function (string, substring) {
      if (!substring) {
        return 0;
      }
      let count = 0;
      let pos = string.indexOf(substring);

      while (pos !== -1) {
        count++;
        pos = string.indexOf(substring, pos + substring.length);
      }

      return count;
    };

    const help = [
      {v1: "start(x,y)", v2: "start(0,0);"},
      {v1: "go(distance)", v2: "go(1);"},
      {v1: "turn(angle)", v2: "turn(90);"},
      {v1: "left(angle)", v2: "left(90);"},
      {v1: "right(angle)", v2: "right(90);"},
      {v1: "pillars(number, length, shift = 0, direction = UP)", v2: "pillars(3, 10, 0, DOWN);"},
      {v1: "moving_pillars(number, length, shift = 1, direction = DOWN)", v2: "moving_pillars(3, 10, 1, DOWN);"},
      {v1: "staircase(number, size, direction = DOWN)", v2: "staircase(3, 1, DOWN);"},
      {v1: "repeat([start], end){...}", v2: "repeat(5){\n   \n}"},
      {v1: "random(range-start, range-end)", v2: "random(0,1);"},
      {v1: "sin(alpha)", v2: "sin();"},
      {v1: "cos(alpha)", v2: "cos();"},
      {v1: "tan(alpha)", v2: "tan();"},
      {v1: "atan(tangent)", v2: "atan();"},
    ];
    const slices = {};
    for (let i = 0; i < help.length; i++) {
      for (let j = 1; j < help[i].v1.length; j++) {
        const sub = help[i].v1.substring(0, j);
        if (!slices[sub]) {
          slices[sub] = [];
        }
        slices[sub].push(help[i]);
      }
      slices[help[i].v1] = [help[i]];
    }

    function refresh() {
      script = command_input_element.value;
      try {
        canvas.clearRect(0, 0, width, height);
        interpret({canvas: canvas, x: tx, y: ty, angle: tangle, unit: 10, width: width, height: height}, script);
      } catch (e) {
        document.getElementById('log').innerHTML = e;
      }
    }

    command_input_element.onkeyup = function handle_key_input(event) {
      if (event.key === 'Tab') {
        const script = command_input_element.value;
        event.preventDefault();
        const cursor_position = command_input_element.selectionStart;
        const textUpToCursor = script.slice(0, cursor_position);
        const startOfLine = textUpToCursor.lastIndexOf('\n') + 1;
        const endOfLine = script.indexOf('\n', cursor_position);
        const lineEndPosition = endOfLine === -1 ? script.length : endOfLine;
        const currentLineText = script.slice(startOfLine, lineEndPosition).trim();

        if (slices[currentLineText]) {
          const helpOptions = slices[currentLineText].map(x => x.v2);
          const firstOption = helpOptions[0];

          command_input_element.value = script.slice(0, startOfLine) + firstOption + script.slice(lineEndPosition);
          command_input_element.setSelectionRange(startOfLine + firstOption.length, startOfLine + firstOption.length);
          command_input_element.focus();
          help_element.style.visibility = 'hidden';
          refresh();
        }
      }
      if (!['ArrowUp', 'ArrowDown', 'ArrowLeft', 'ArrowRight'].includes(event.key)) {
        script = command_input_element.value;

        help_element.style.visibility = 'hidden';
        const cursor_position = command_input_element.selectionStart;
        const textUpToCursor = script.slice(0, cursor_position);
        const startOfLine = textUpToCursor.lastIndexOf('\n') + 1;

        const endOfLine = script.indexOf('\n', cursor_position);
        const lineEndPosition = endOfLine === -1 ? script.length : endOfLine;

        const currentLineText = script.slice(startOfLine, lineEndPosition);
        if (currentLineText.length > 0) {
          const command = currentLineText.trim();
          if (slices[command]) {
            const help = slices[command].map(x => x.v1);
            let help_text = "";
            for (let x = 0; x < help.length; x++) {
              help_text += `<div id="l-${x}">${help[x]}</div>`;
            }

            const computedStyle = window.getComputedStyle(command_input_element);
            const fontSize = parseFloat(computedStyle.fontSize);
            const lineHeight = computedStyle.lineHeight === 'normal' ? fontSize * 1.2 : parseFloat(computedStyle.lineHeight);

            const textBounding = command_input_element.getBoundingClientRect();
            const topPosition = textBounding.top + window.scrollY + (count(script, '\n') + 4) * lineHeight;

            help_element.style.visibility = 'visible';
            help_element.style.left = `${textBounding.left + window.scrollX}px`;
            help_element.style.top = `${topPosition - help_element.offsetHeight}px`;
            help_element.innerHTML = help_text;
            help_element.style.display = 'block';
          }
        }
        refresh();
      }
    }
    //main
    refresh();
  })
();