/**
 * Copyright 2023 Crisp Advice
 * We believe in Finnish
 */
{
  // Modules
  let Layout = require("Layout");
  let locale = require("locale");
  let storage = require("Storage");

  // Global variables
  const SWAP_SIDE_BUZZ_MILLISECONDS = 50;
  const CARD_DATA_FILE = "flashcards.data.json";
  const CARD_SETTINGS_FILE = "flashcards.settings.json";
  const CARD_EMPTY = "no cards found";
 
  let cards = [];
  let cardIndex = 0;
  let backSide = false;
  let drawTimeout;
  let fontSizes = ["15%","20%","25%"];
  let lastDragX = 0;
  let lastDragY = 0;

  let settings = Object.assign({
    listId: "",
    fontSize: 1,
    cardWidth: 9,
    swipeGesture: 1
  }, storage.readJSON(CARD_SETTINGS_FILE, true) || {});

  // Cards data
  let wordWrap = function (textStr, maxLength) {
    if (maxLength == undefined) {
      maxLength = settings.cardWidth;
    }
    let res = '';
    let str = textStr.trim();
    while (str.length > maxLength) {
      let found = false;
      // Inserts new line at first whitespace of the line
      for (let i = maxLength - 1; i > 0; i--) {
        if (str.charAt(i)==' ') {
          res = res + [str.slice(0, i), "\n"].join('');
          str = str.slice(i + 1);
          found = true;
          break;
        }
      }
      // Inserts new line at MAX_LENGTH position, the word is too long to wrap
      if (!found) {
        res += [str.slice(0, maxLength), "\n"].join('');
        str = str.slice(maxLength);
      }
    }
    return res + str;
  }

  let loadLocalCards = function() {
    var cardsJSON = "";
    if (storage.read(CARD_DATA_FILE))
    {
      cardsJSON = storage.readJSON(CARD_DATA_FILE, 1)  || {};
    }
    refreshCards(cardsJSON,false);
  }

  let refreshCards = function(cardsJSON,showMsg)
  {
    cardIndex = 0;
    backSide = false;
    cards = [];

    if (cardsJSON && cardsJSON.length) {
      cardsJSON.forEach(card => {
        cards.push([ wordWrap(card.name), wordWrap(card.desc) ]);
      });
    }

    if (!cards.length) {
      cards.push([ wordWrap(CARD_EMPTY), wordWrap(CARD_EMPTY) ]);
      drawMessage("e: cards not found");
    } else if (showMsg) {
      drawMessage("i: cards refreshed");
    }
  }

  // Drawing a card
  let queueDraw = function() {
    let timeout = 60000;
    if (drawTimeout) clearTimeout(drawTimeout);
    drawTimeout = setTimeout(function() {
      drawTimeout = undefined;
      draw();
    }, timeout - (Date.now() % timeout));
  };

  let cardLayout = new Layout( {
    type:"v", c: [
      {type:"txt", font:"6x8:3", label:"", id:"widgets", fillx:1 },
      {type:"txt", font:fontSizes[settings.fontSize], label:"ABCDEFGHIJ KLMNOPQRST UVWXYZÅÖÄ", filly:1, fillx:1, id:"card" },
      {type:"txt", font:"6x8:2", label:"00:00", id:"clock", fillx:1, bgCol:g.theme.fg, col:g.theme.bg }
    ]
  }, {lazy:true});

  let drawCard = function() {
    cardLayout.card.label = cards[cardIndex][backSide ? 1 : 0];
    cardLayout.clock.label = locale.time(new Date(),1);
    cardLayout.render();
  }

  let drawMessage = function(msg) {
    cardLayout.card.label = wordWrap(msg);
    cardLayout.render();
    console.log(msg);
  }

  let draw = function() {
    drawCard();
    Bangle.drawWidgets();
    queueDraw();
  }

  let swipeCard = function(forward)
  {
    if(forward) {
      cardIndex = (cardIndex + 1) % cards.length;
    }
    else if(--cardIndex < 0) {
      cardIndex = cards.length - 1;
    }
    drawCard();
  }

  // Handle a touch: swap card side
  let handleTouch = function(zone, event) {
    backSide = !backSide;
    drawCard();
    Bangle.buzz(SWAP_SIDE_BUZZ_MILLISECONDS);
  }

  // Handle a stroke event: cycle cards
  let handleStroke = function(event) {
    let first_x = event.xy[0];
    let last_x = event.xy[event.xy.length - 2];
    swipeCard((last_x - first_x) > 0);
  }

  // Handle a drag event: cycle cards
  let handleDrag = function(event) {
    let isFingerReleased = (event.b === 0);
    if(isFingerReleased) {
      let isHorizontalDrag = (Math.abs(lastDragX) >= Math.abs(lastDragY)) &&
                            (lastDragX !== 0);
      if(isHorizontalDrag) {
        swipeCard(lastDragX > 0);
      }
    }
    else {
      lastDragX = event.dx;
      lastDragY = event.dy;
    }
  }

  // Ensure pressing the button goes to the launcher (by making this seem like a clock?)
  Bangle.setUI({mode:"clock", remove:function() {
    if (drawTimeout) clearTimeout(drawTimeout);
    drawTimeout = undefined;
    Bangle.removeListener("touch", handleTouch);
    if (settings.swipeGesture) { Bangle.removeListener("drag", handleDrag);} else { Bangle.removeListener("stroke", handleStroke); }  
  }});

  // initialize
  cardLayout.update();
  Bangle.loadWidgets();
  loadLocalCards();

  Bangle.on("touch", handleTouch);
  if (settings.swipeGesture) { Bangle.on("drag", handleDrag); } else { Bangle.on("stroke", handleStroke); }

  // On start: display the first card
  g.clear();
  draw();
}