import { qs, sprint, locationOf, defer } from "./utils/core";
import Queue from "./utils/queue";
import EpubCFI from "./epubcfi";
import { EVENTS } from "./utils/constants";
import EventEmitter from "event-emitter";

/**
 * Find Locations for a Book
 * @param {Spine} spine
 * @param {request} request
 * @param {number} [pause=100]
 */
class Locations {
  constructor(spine, request, pause) {
    this.spine = spine;
    this.request = request;
    this.pause = pause || 100;

    this.q = new Queue(this);
    this.epubcfi = new EpubCFI();

    this._locations = [];
    this.total = 0;

    this.break = 150;

    this._current = 0;

    this.currentLocation = "";
    this._currentCfi = "";
    this.processingTimeout = undefined;
  }

  /**
   * Load all of sections in the book to generate locations
   * @param  {int} chars how many chars to split on
   * @return {object} locations
   */
  generate(chars) {
    if (chars) {
      this.break = chars;
    }

    this.q.pause();

    this.spine.each(
      function (section) {
        if (section.linear) {
          this.q.enqueue(this.process.bind(this), section);
        }
      }.bind(this)
    );

    return this.q.run().then(
      function () {
        this.total = this._locations.length - 1;

        if (this._currentCfi) {
          this.currentLocation = this._currentCfi;
        }

        return this._locations;
        // console.log(this.percentage(this.book.rendition.location.start), this.percentage(this.book.rendition.location.end));
      }.bind(this)
    );
  }

  createRange() {
    return {
      startContainer: undefined,
      startOffset: undefined,
      endContainer: undefined,
      endOffset: undefined,
    };
  }

  process(section) {
    return section.load(this.request).then(
      function (contents) {
        var completed = new defer();
        var locations = this.parse(contents, section.cfiBase);
        this._locations = this._locations.concat(locations);

        section.unload();

        this.processingTimeout = setTimeout(
          () => completed.resolve(locations),
          this.pause
        );
        return completed.promise;
      }.bind(this)
    );
  }

  parse(contents, cfiBase, chars) {
    var locations = [];
    var range;
    var doc = contents.ownerDocument;
    var body = qs(doc, "body");
    var counter = 0;
    var prev;
    var _break = chars || this.break;
    var parser = function (node) {
      var len = node.length;
      var dist;
      var pos = 0;

      if (node.textContent.trim().length === 0) {
        return false; // continue
      }

      // Start range
      if (counter == 0) {
        range = this.createRange();
        range.startContainer = node;
        range.startOffset = 0;
      }

      dist = _break - counter;

      // Node is smaller than a break,
      // skip over it
      if (dist > len) {
        counter += len;
        pos = len;
      }

      while (pos < len) {
        dist = _break - counter;

        if (counter === 0) {
          // Start new range
          pos += 1;
          range = this.createRange();
          range.startContainer = node;
          range.startOffset = pos;
        }

        // pos += dist;

        // Gone over
        if (pos + dist >= len) {
          // Continue counter for next node
          counter += len - pos;
          // break
          pos = len;
          // At End
        } else {
          // Advance pos
          pos += dist;

          // End the previous range
          range.endContainer = node;
          range.endOffset = pos;
          // cfi = section.cfiFromRange(range);
          let cfi = new EpubCFI(range, cfiBase).toString();
          locations.push(cfi);
          counter = 0;
        }
      }
      prev = node;
    };

    sprint(body, parser.bind(this));

    // Close remaining
    if (range && range.startContainer && prev) {
      range.endContainer = prev;
      range.endOffset = prev.length;
      let cfi = new EpubCFI(range, cfiBase).toString();
      locations.push(cfi);
      counter = 0;
    }

    return locations;
  }

  /**
   * Get a location from an EpubCFI
   * @param {EpubCFI} cfi
   * @return {number}
   */
  locationFromCfi(cfi) {
    let loc;
    if (EpubCFI.prototype.isCfiString(cfi)) {
      cfi = new EpubCFI(cfi);
    }
    // Check if the location has not been set yet
    if (this._locations.length === 0) {
      return -1;
    }

    loc = locationOf(cfi, this._locations, this.epubcfi.compare);

    if (loc > this.total) {
      return this.total;
    }

    return loc;
  }

  /**
   * Get a percentage position in locations from an EpubCFI
   * @param {EpubCFI} cfi
   * @return {number}
   */
  percentageFromCfi(cfi) {
    if (this._locations.length === 0) {
      return null;
    }
    // Find closest cfi
    var loc = this.locationFromCfi(cfi);
    // Get percentage in total
    return this.percentageFromLocation(loc);
  }

  /**
   * Get a percentage position from a location index
   * @param {number} location
   * @return {number}
   */
  percentageFromLocation(loc) {
    if (!loc || !this.total) {
      return 0;
    }

    return loc / this.total;
  }

  /**
   * Get an EpubCFI from location index
   * @param {number} loc
   * @return {EpubCFI} cfi
   */
  cfiFromLocation(loc) {
    var cfi = -1;
    // check that pg is an int
    if (typeof loc != "number") {
      loc = parseInt(loc);
    }

    if (loc >= 0 && loc < this._locations.length) {
      cfi = this._locations[loc];
    }

    return cfi;
  }

  /**
   * Get an EpubCFI from location percentage
   * @param {number} percentage
   * @return {EpubCFI} cfi
   */
  cfiFromPercentage(percentage) {
    let loc;
    if (percentage > 1) {
      console.warn("Normalize cfiFromPercentage value to between 0 - 1");
    }

    // Make sure 1 goes to very end
    if (percentage >= 1) {
      let cfi = new EpubCFI(this._locations[this.total]);
      cfi.collapse();
      return cfi.toString();
    }

    loc = Math.ceil(this.total * percentage);
    return this.cfiFromLocation(loc);
  }

  /**
   * Load locations from JSON
   * @param {json} locations
   */
  load(locations) {
    if (typeof locations === "string") {
      this._locations = JSON.parse(locations);
    } else {
      this._locations = locations;
    }
    this.total = this._locations.length - 1;
    return this._locations;
  }

  /**
   * Save locations to JSON
   * @return {json}
   */
  save() {
    return JSON.stringify(this._locations);
  }

  getCurrent() {
    return this._current;
  }

  setCurrent(curr) {
    var loc;

    if (typeof curr == "string") {
      this._currentCfi = curr;
    } else if (typeof curr == "number") {
      this._current = curr;
    } else {
      return;
    }

    if (this._locations.length === 0) {
      return;
    }

    if (typeof curr == "string") {
      loc = this.locationFromCfi(curr);
      this._current = loc;
    } else {
      loc = curr;
    }

    this.emit(EVENTS.LOCATIONS.CHANGED, {
      percentage: this.percentageFromLocation(loc),
    });
  }

  /**
   * Get the current location
   */
  get currentLocation() {
    return this._current;
  }

  /**
   * Set the current location
   */
  set currentLocation(curr) {
    this.setCurrent(curr);
  }

  /**
   * Locations length
   */
  length() {
    return this._locations.length;
  }

  destroy() {
    this.spine = undefined;
    this.request = undefined;
    this.pause = undefined;

    this.q.stop();
    this.q = undefined;
    this.epubcfi = undefined;

    this._locations = undefined;
    this.total = undefined;

    this.break = undefined;
    this._current = undefined;

    this.currentLocation = undefined;
    this._currentCfi = undefined;
    clearTimeout(this.processingTimeout);
  }
}

EventEmitter(Locations.prototype);

export default Locations;
