let util = require('../../../../util');
let ComponentUtil = require('./ComponentUtil').default;
let LabelSplitter = require('./LabelSplitter').default;

/**
 * @typedef {'bold'|'ital'|'boldital'|'mono'|'normal'} MultiFontStyle
 *
 * The allowed specifiers of multi-fonts.
 */

/**
 * @typedef {{color:string, size:number, face:string, mod:string, vadjust:number}} MultiFontOptions
 *
 * The full set of options of a given multi-font.
 */

/**
 * @typedef {Array.<object>} Pile
 *
 * Sequence of option objects, the order is significant.
 * The sequence is used to determine the value of a given option.
 *
 * Usage principles:
 *
 *  - All search is done in the sequence of the pile.
 *  - As soon as a value is found, the searching stops.
 *  - prototypes are totally ignored. The idea is to add option objects used as prototypes
 *    to the pile, in the correct order.
 */


/**
 * List of special styles for multi-fonts
 * @private
 */
const multiFontStyle = ['bold', 'ital', 'boldital', 'mono'];

/**
 * A Label to be used for Nodes or Edges.
 */
class Label {

  /**
   * @param {Object} body
   * @param {Object} options
   * @param {boolean} [edgelabel=false]
   */
  constructor(body, options, edgelabel = false) {
    this.body = body;
    this.pointToSelf = false;
    this.baseSize = undefined;
    this.fontOptions = {};      // instance variable containing the *instance-local* font options
    this.setOptions(options);
    this.size = {top: 0, left: 0, width: 0, height: 0, yLine: 0}; // could be cached
    this.isEdgeLabel = edgelabel;
  }


  /**
   * @param {Object} options the options of the parent Node-instance
   */
  setOptions(options) {
    this.elementOptions = options;  // Reference to the options of the parent Node-instance 

    this.initFontOptions(options.font);

    if (options.label !== undefined && options.label !== null && options.label !== '') {
      this.labelDirty = true;
    }

    if (options.font !== undefined && options.font !== null) { // font options can be deleted at various levels
      if (typeof options.font === 'string') {
        this.baseSize = this.fontOptions.size;
      }
      else if (typeof options.font === 'object') {
        let size = options.font.size;
 
        if (size !== undefined) {
          this.baseSize = size;
        }
      }
    }
  }


  /**
   * Init the font Options structure.
   *
   * Member fontOptions serves as an accumulator for the current font options.
   * As such, it needs to be completely separated from the node options.
   *
   * @param {Object} newFontOptions the new font options to process
   * @private
   */
  initFontOptions(newFontOptions) {
    // Prepare the multi-font option objects.
    // These will be filled in propagateFonts(), if required
    util.forEach(multiFontStyle, (style) => {
      this.fontOptions[style] = {};
    });

    // Handle shorthand option, if present
    if (Label.parseFontString(this.fontOptions, newFontOptions)) {
      this.fontOptions.vadjust = 0;
      return;
    }

    // Copy over the non-multifont options, if specified
    util.forEach(newFontOptions, (prop, n) => {
      if (prop !== undefined && prop !== null && typeof prop !== 'object') {
        this.fontOptions[n] = prop;
      }
    });
  }


  /**
   * If in-variable is a string, parse it as a font specifier.
   *
   * Note that following is not done here and have to be done after the call:
   * - No number conversion (size)
   * - Not all font options are set (vadjust, mod)
   *
   * @param {Object} outOptions  out-parameter, object in which to store the parse results (if any)
   * @param {Object} inOptions  font options to parse
   * @return {boolean} true if font parsed as string, false otherwise
   * @static
   */
  static parseFontString(outOptions, inOptions) {
    if (!inOptions || typeof inOptions !== 'string') return false;

    let newOptionsArray = inOptions.split(" ");

    outOptions.size  = newOptionsArray[0].replace("px",'');
    outOptions.face  = newOptionsArray[1];
    outOptions.color = newOptionsArray[2];

    return true;
  }


  /**
   * Set the width and height constraints based on 'nearest' value
   * @param {Array} pile array of option objects to consider
   * @private
   */
  constrain(pile) {
    this.fontOptions.constrainWidth = false;
    this.fontOptions.maxWdt = -1;
    this.fontOptions.minWdt = -1;

    let widthConstraint = util.topMost(pile, 'widthConstraint');
    if (typeof widthConstraint === 'number') {
      this.fontOptions.maxWdt = Number(widthConstraint);
      this.fontOptions.minWdt = Number(widthConstraint);
    } else if (typeof widthConstraint === 'object') {
      let widthConstraintMaximum = util.topMost(pile, ['widthConstraint', 'maximum']);
      if (typeof widthConstraintMaximum === 'number') {
        this.fontOptions.maxWdt = Number(widthConstraintMaximum);
      }
      let widthConstraintMinimum = util.topMost(pile, ['widthConstraint', 'minimum'])
      if (typeof widthConstraintMinimum === 'number') {
        this.fontOptions.minWdt = Number(widthConstraintMinimum);
      }
    }

    this.fontOptions.constrainHeight = false;
    this.fontOptions.minHgt = -1;
    this.fontOptions.valign = 'middle';

    let heightConstraint = util.topMost(pile, 'heightConstraint');
    if (typeof heightConstraint === 'number') {
      this.fontOptions.minHgt = Number(heightConstraint);
    } else if (typeof heightConstraint === 'object') {
      let heightConstraintMinimum = util.topMost(pile, ['heightConstraint', 'minimum']);
      if (typeof heightConstraintMinimum === 'number') {
        this.fontOptions.minHgt = Number(heightConstraintMinimum);
      }
      let heightConstraintValign = util.topMost(pile, ['heightConstraint', 'valign']);
      if (typeof heightConstraintValign === 'string') {
        if ((heightConstraintValign === 'top')||(heightConstraintValign === 'bottom')) {
            this.fontOptions.valign = heightConstraintValign;
        }
      }
    }
  }


  /**
   * Set options and update internal state
   *
   * @param {Object} options  options to set
   * @param {Array}  pile     array of option objects to consider for option 'chosen'
   */
  update(options, pile) {
    this.setOptions(options, true);
    this.constrain(pile);
    this.propagateFonts(pile);
    this.fontOptions.chooser = ComponentUtil.choosify('label', pile);
  }


  /**
   * When margins are set in an element, adjust sizes is called to remove them
   * from the width/height constraints. This must be done prior to label sizing.
   *
   * @param {{top: number, right: number, bottom: number, left: number}} margins
   */
  adjustSizes(margins) {
    let widthBias =  (margins) ? (margins.right + margins.left) : 0;
    if (this.fontOptions.constrainWidth) {
      this.fontOptions.maxWdt -= widthBias;
      this.fontOptions.minWdt -= widthBias;
    }
    let heightBias = (margins) ? (margins.top + margins.bottom)  : 0;
    if (this.fontOptions.constrainHeight) {
      this.fontOptions.minHgt -= heightBias;
    }
  }


/////////////////////////////////////////////////////////
// Methods for handling options piles
// Eventually, these will be moved to a separate class
/////////////////////////////////////////////////////////

  /**
   * Add the font members of the passed list of option objects to the pile.
   *
   * @param {Pile} dstPile  pile of option objects add to 
   * @param {Pile} srcPile  pile of option objects to take font options from
   * @private
   */
  addFontOptionsToPile(dstPile, srcPile) {
    for (let i = 0; i < srcPile.length; ++i) {
      this.addFontToPile(dstPile, srcPile[i]);
    }
  }


  /**
   * Add given font option object to the list of objects (the 'pile') to consider for determining
   * multi-font option values.
   *
   * @param {Pile} pile  pile of option objects to use
   * @param {object} options  instance to add to pile
   * @private
   */
  addFontToPile(pile, options) {
    if (options === undefined) return;
    if (options.font === undefined || options.font === null) return;

    let item = options.font;
    pile.push(item);
  }


  /**
   * Collect all own-property values from the font pile that aren't multi-font option objectss.
   *
   * @param {Pile} pile  pile of option objects to use
   * @returns {object} object with all current own basic font properties
   * @private
   */
  getBasicOptions(pile) {
    let ret = {};

    // Scans the whole pile to get all options present
    for (let n = 0; n < pile.length; ++n) {
      let fontOptions = pile[n];

      // Convert shorthand if necessary
      let tmpShorthand = {};
      if (Label.parseFontString(tmpShorthand, fontOptions)) {
        fontOptions = tmpShorthand;
      }

      util.forEach(fontOptions, (opt, name) => {
        if (opt === undefined) return;        // multi-font option need not be present 
        if (ret.hasOwnProperty(name)) return; // Keep first value we encounter

        if (multiFontStyle.indexOf(name) !== -1) {
          // Skip multi-font properties but we do need the structure
          ret[name] = {};
        } else {
          ret[name] = opt;
        }
      });
    }

    return ret;
  }


  /**
   * Return the value for given option for the given multi-font.
   *
   * All available option objects are trawled in the set order to construct the option values.
   *
   * ---------------------------------------------------------------------
   * ## Traversal of pile for multi-fonts
   *
   * The determination of multi-font option values is a special case, because any values not
   * present in the multi-font options should by definition be taken from the main font options,
   * i.e. from the current 'parent' object of the multi-font option.
   *
   * ### Search order for multi-fonts
   *
   * 'bold' used as example:
   *
   *   - search in option group 'bold' in local properties
   *   - search in main font option group in local properties
   *
   * ---------------------------------------------------------------------
   *
   * @param {Pile} pile  pile of option objects to use
   * @param {MultiFontStyle} multiName sub path for the multi-font
   * @param {string} option  the option to search for, for the given multi-font
   * @returns {string|number} the value for the given option
   * @private
   */
  getFontOption(pile, multiName, option) {
    let multiFont;

    // Search multi font in local properties
    for (let n = 0; n < pile.length; ++n) {
      let fontOptions = pile[n];

      if (fontOptions.hasOwnProperty(multiName)) {
        multiFont = fontOptions[multiName];
        if (multiFont === undefined || multiFont === null) continue;

        // Convert shorthand if necessary
        // TODO: inefficient to do this conversion every time; find a better way.
        let tmpShorthand = {};
        if (Label.parseFontString(tmpShorthand, multiFont)) {
          multiFont = tmpShorthand;
        }

        if (multiFont.hasOwnProperty(option)) {
          return multiFont[option];
        }
      }
    }

    // Option is not mentioned in the multi font options; take it from the parent font options.
    // These have already been converted with getBasicOptions(), so use the converted values.
    if (this.fontOptions.hasOwnProperty(option)) {
      return this.fontOptions[option];
    }

    // A value **must** be found; you should never get here.
    throw new Error("Did not find value for multi-font for property: '" + option + "'");
  }


  /**
   * Return all options values for the given multi-font.
   *
   * All available option objects are trawled in the set order to construct the option values.
   *
   * @param {Pile} pile  pile of option objects to use
   * @param {MultiFontStyle} multiName sub path for the mod-font
   * @returns {MultiFontOptions}
   * @private
   */
  getFontOptions(pile, multiName) {
    let result = {};
    let optionNames = ['color', 'size', 'face', 'mod', 'vadjust'];  // List of allowed options per multi-font

    for (let i = 0; i < optionNames.length; ++i) {
      let mod = optionNames[i];
      result[mod] = this.getFontOption(pile, multiName, mod);
    }

    return result;
  }

/////////////////////////////////////////////////////////
// End methods for handling options piles
/////////////////////////////////////////////////////////


  /**
   * Collapse the font options for the multi-font to single objects, from
   * the chain of option objects passed (the 'pile').
   *
   * @param {Pile} pile  sequence of option objects to consider.
   *                     First item in list assumed to be the newly set options.
   */
  propagateFonts(pile) {
    let fontPile = [];   // sequence of font objects to consider, order important

    // Note that this.elementOptions is not used here.
    this.addFontOptionsToPile(fontPile, pile);
    this.fontOptions = this.getBasicOptions(fontPile);

    // We set multifont values even if multi === false, for consistency (things break otherwise)
    for (let i = 0; i < multiFontStyle.length; ++i) {
      let mod = multiFontStyle[i];
      let modOptions  = this.fontOptions[mod];
      let tmpMultiFontOptions = this.getFontOptions(fontPile, mod);

      // Copy over found values
      util.forEach(tmpMultiFontOptions, (option, n) => {
        modOptions[n] = option;
      });

      modOptions.size    = Number(modOptions.size);
      modOptions.vadjust = Number(modOptions.vadjust);
    }
  }


  /**
   * Main function. This is called from anything that wants to draw a label.
   * @param {CanvasRenderingContext2D} ctx
   * @param {number} x
   * @param {number} y
   * @param {boolean} selected
   * @param {boolean} hover
   * @param {string} [baseline='middle']
   */
  draw(ctx, x, y, selected, hover, baseline = 'middle') {
    // if no label, return
    if (this.elementOptions.label === undefined)
      return;

    // check if we have to render the label
    let viewFontSize = this.fontOptions.size * this.body.view.scale;
    if (this.elementOptions.label && viewFontSize < this.elementOptions.scaling.label.drawThreshold - 1)
      return;

    // This ensures that there will not be HUGE letters on screen
    // by setting an upper limit on the visible text size (regardless of zoomLevel)
    if (viewFontSize >= this.elementOptions.scaling.label.maxVisible) {
      viewFontSize = Number(this.elementOptions.scaling.label.maxVisible) / this.body.view.scale;
    }

    // update the size cache if required
    this.calculateLabelSize(ctx, selected, hover, x, y, baseline);
    this._drawBackground(ctx, this.size.left, this.size.top);
    this._drawText(ctx, x, this.size.yLine, baseline, viewFontSize);

  }

  /**
   * Draws the label background
   * @param {CanvasRenderingContext2D} ctx
   * @param {number} x
   * @param {number} y
   * @private
   */
  _drawBackground(ctx, x, y) {
    if (this.fontOptions.background !== undefined && this.fontOptions.background !== "none") {
      ctx.fillStyle = this.fontOptions.background;

      let lineMargin = 2;

      if (this.isEdgeLabel) {
        switch (this.fontOptions.align) {
          case 'middle':
            ctx.fillRect(-this.size.width * 0.5, -this.size.height * 0.5, this.size.width, this.size.height);
            break;
          case 'top':
            ctx.fillRect(-this.size.width * 0.5, -(this.size.height + lineMargin), this.size.width, this.size.height);
            break;
          case 'bottom':
            ctx.fillRect(-this.size.width * 0.5, lineMargin, this.size.width, this.size.height);
            break;
          default:
            ctx.fillRect(x, y - 0.5*lineMargin, this.size.width, this.size.height);
            break;
        }
      } else {
        ctx.fillRect(x, y - 0.5*lineMargin, this.size.width, this.size.height);
      }
    }
  }


  /**
   *
   * @param {CanvasRenderingContext2D} ctx
   * @param {number} x
   * @param {number} y
   * @param {string} [baseline='middle']
   * @param {number} viewFontSize 
   * @private
   */
  _drawText(ctx, x, y, baseline = 'middle', viewFontSize) {

    [x, y] = this._setAlignment(ctx, x, y, baseline);

    ctx.textAlign = 'left';
    x = x - this.size.width / 2; // Shift label 1/2-distance to the left
    if ((this.fontOptions.valign) && (this.size.height > this.size.labelHeight)) {
      if (this.fontOptions.valign === 'top') {
        y -= (this.size.height - this.size.labelHeight) / 2;
      }
      if (this.fontOptions.valign === 'bottom') {
        y += (this.size.height - this.size.labelHeight) / 2;
      }
    }

    // draw the text
    for (let i = 0; i < this.lineCount; i++) {
      let line = this.lines[i];
      if (line && line.blocks) {
        let width = 0;
        if (this.isEdgeLabel || this.fontOptions.align === 'center') {
          width += (this.size.width - line.width) / 2
        } else if (this.fontOptions.align === 'right') {
          width += (this.size.width - line.width)
        }
        for (let j = 0; j < line.blocks.length; j++) {
          let block = line.blocks[j];
          ctx.font = block.font;
          let [fontColor, strokeColor] = this._getColor(block.color, viewFontSize, block.strokeColor);
          if (block.strokeWidth > 0) {
            ctx.lineWidth = block.strokeWidth;
            ctx.strokeStyle = strokeColor;
            ctx.lineJoin = 'round';
          }
          ctx.fillStyle = fontColor;

          if (block.strokeWidth > 0) {
            ctx.strokeText(block.text, x + width, y + block.vadjust);
          }
          ctx.fillText(block.text, x + width, y + block.vadjust);
          width += block.width;
        }
        y += line.height;
      }
    }
  }

  /**
   *
   * @param {CanvasRenderingContext2D} ctx
   * @param {number} x
   * @param {number} y
   * @param {string} baseline
   * @returns {Array.<number>}
   * @private
   */
  _setAlignment(ctx, x, y, baseline) {
    // check for label alignment (for edges)
    // TODO: make alignment for nodes
    if (this.isEdgeLabel && this.fontOptions.align !== 'horizontal' && this.pointToSelf === false) {
      x = 0;
      y = 0;

      let lineMargin = 2;
      if (this.fontOptions.align === 'top') {
        ctx.textBaseline = 'alphabetic';
        y -= 2 * lineMargin; // distance from edge, required because we use alphabetic. Alphabetic has less difference between browsers
      }
      else if (this.fontOptions.align === 'bottom') {
        ctx.textBaseline = 'hanging';
        y += 2 * lineMargin;// distance from edge, required because we use hanging. Hanging has less difference between browsers
      }
      else {
        ctx.textBaseline = 'middle';
      }
    }
    else {
      ctx.textBaseline = baseline;
    }
    return [x,y];
  }

  /**
   * fade in when relative scale is between threshold and threshold - 1.
   * If the relative scale would be smaller than threshold -1 the draw function would have returned before coming here.
   *
   * @param {string} color  The font color to use
   * @param {number} viewFontSize
   * @param {string} initialStrokeColor
   * @returns {Array.<string>} An array containing the font color and stroke color
   * @private
   */
  _getColor(color, viewFontSize, initialStrokeColor) {
    let fontColor = color || '#000000';
    let strokeColor = initialStrokeColor || '#ffffff';
    if (viewFontSize <= this.elementOptions.scaling.label.drawThreshold) {
      let opacity = Math.max(0, Math.min(1, 1 - (this.elementOptions.scaling.label.drawThreshold - viewFontSize)));
      fontColor = util.overrideOpacity(fontColor, opacity);
      strokeColor = util.overrideOpacity(strokeColor, opacity);
    }
    return [fontColor, strokeColor];
  }

  /**
   *
   * @param {CanvasRenderingContext2D} ctx
   * @param {boolean} selected
   * @param {boolean} hover
   * @returns {{width: number, height: number}}
   */
  getTextSize(ctx, selected = false, hover = false) {
    this._processLabel(ctx, selected, hover);
    return {
      width: this.size.width,
      height: this.size.height,
      lineCount: this.lineCount
    };
  }


  /**
   *
   * @param {CanvasRenderingContext2D} ctx
   * @param {boolean} selected
   * @param {boolean} hover
   * @param {number} [x=0]
   * @param {number} [y=0]
   * @param {'middle'|'hanging'} [baseline='middle']
   */
  calculateLabelSize(ctx, selected, hover, x = 0, y = 0, baseline = 'middle') {
    this._processLabel(ctx, selected, hover);
    this.size.left = x - this.size.width * 0.5;
    this.size.top = y - this.size.height * 0.5;
    this.size.yLine = y + (1 - this.lineCount) * 0.5 * this.fontOptions.size;
    if (baseline === "hanging") {
      this.size.top += 0.5 * this.fontOptions.size;
      this.size.top += 4;   // distance from node, required because we use hanging. Hanging has less difference between browsers
      this.size.yLine += 4; // distance from node
    }
  }


  /**
   *
   * @param {CanvasRenderingContext2D} ctx
   * @param {boolean} selected
   * @param {boolean} hover
   * @param {string} mod
   * @returns {{color, size, face, mod, vadjust, strokeWidth: *, strokeColor: (*|string|allOptions.edges.font.strokeColor|{string}|allOptions.nodes.font.strokeColor|Array)}}
   */
  getFormattingValues(ctx, selected, hover, mod) {
    let getValue = function(fontOptions, mod, option) {
      if (mod === "normal") {
        if (option === 'mod' ) return "";
        return fontOptions[option];
      }

      if (fontOptions[mod][option] !== undefined) {  // Grumbl leaving out test on undefined equals false for "" 
        return fontOptions[mod][option];
      } else {
        // Take from parent font option
        return fontOptions[option];
      }
    };

    let values = {
      color  : getValue(this.fontOptions, mod, 'color'  ),
      size   : getValue(this.fontOptions, mod, 'size'   ),
      face   : getValue(this.fontOptions, mod, 'face'   ),
      mod    : getValue(this.fontOptions, mod, 'mod'    ),
      vadjust: getValue(this.fontOptions, mod, 'vadjust'),
      strokeWidth: this.fontOptions.strokeWidth,
      strokeColor: this.fontOptions.strokeColor
    };
    if (selected || hover) {
      if (mod === "normal" && (this.fontOptions.chooser === true) && (this.elementOptions.labelHighlightBold)) {
          values.mod = 'bold';
      } else {
        if (typeof this.fontOptions.chooser === 'function') {
          this.fontOptions.chooser(values, this.elementOptions.id, selected, hover);
        }
      }
    }

    let fontString = "";
    if (values.mod !== undefined && values.mod !== "") {  // safeguard for undefined - this happened
      fontString += values.mod + " ";
    }
    fontString += values.size + "px " + values.face;

    ctx.font = fontString.replace(/"/g, "");
    values.font = ctx.font;
    values.height = values.size;
    return values;
  }


  /**
   *
   * @param {boolean} selected
   * @param {boolean} hover
   * @returns {boolean}
   */
  differentState(selected, hover) {
    return ((selected !== this.selectedState) || (hover !== this.hoverState));
  }
   

  /**
   * This explodes the passed text into lines and determines the width, height and number of lines.
   *
   * @param {CanvasRenderingContext2D} ctx
   * @param {boolean} selected
   * @param {boolean} hover
   * @param {string} inText  the text to explode
   * @returns {{width, height, lines}|*}
   * @private
   */
  _processLabelText(ctx, selected, hover, inText) {
    let splitter = new LabelSplitter(ctx, this, selected, hover);
    return splitter.process(inText);
  }


  /**
   * This explodes the label string into lines and sets the width, height and number of lines.
   * @param {CanvasRenderingContext2D} ctx
   * @param {boolean} selected
   * @param {boolean} hover
   * @private
   */
  _processLabel(ctx, selected, hover) {

    if(this.labelDirty === false && !this.differentState(selected,hover))
      return;
    
    let state = this._processLabelText(ctx, selected, hover, this.elementOptions.label);

    if ((this.fontOptions.minWdt > 0) && (state.width < this.fontOptions.minWdt)) {
      state.width = this.fontOptions.minWdt;
    }

    this.size.labelHeight =state.height;
    if ((this.fontOptions.minHgt > 0) && (state.height < this.fontOptions.minHgt)) {
      state.height = this.fontOptions.minHgt;
    }

    this.lines = state.lines;
    this.lineCount = state.lines.length;
    this.size.width = state.width;
    this.size.height = state.height;
    this.selectedState = selected;
    this.hoverState = hover;

    this.labelDirty = false;
  }
}

export default Label;