/**
 * layout.js - layout element for blessed
 * Copyright (c) 2013-2015, Christopher Jeffrey and contributors (MIT License).
 * https://github.com/chjj/blessed
 */

/**
 * Modules
 */

var Node = require('./node');
var Element = require('./element');

/**
 * Layout
 */

function Layout(options) {
  if (!(this instanceof Node)) {
    return new Layout(options);
  }

  options = options || {};

  if ((options.width == null
      && (options.left == null && options.right == null))
      || (options.height == null
      && (options.top == null && options.bottom == null))) {
    throw new Error('`Layout` must have a width and height!');
  }

  options.layout = options.layout || 'inline';

  Element.call(this, options);

  if (options.renderer) {
    this.renderer = options.renderer;
  }
}

Layout.prototype.__proto__ = Element.prototype;

Layout.prototype.type = 'layout';

Layout.prototype.isRendered = function(el) {
  if (!el.lpos) return false;
  return (el.lpos.xl - el.lpos.xi) > 0
      && (el.lpos.yl - el.lpos.yi) > 0;
};

Layout.prototype.getLast = function(i) {
  while (this.children[--i]) {
    var el = this.children[i];
    if (this.isRendered(el)) return el;
  }
};

Layout.prototype.getLastCoords = function(i) {
  var last = this.getLast(i);
  if (last) return last.lpos;
};

Layout.prototype._renderCoords = function() {
  var coords = this._getCoords(true);
  var children = this.children;
  this.children = [];
  this._render();
  this.children = children;
  return coords;
};

Layout.prototype.renderer = function(coords) {
  var self = this;

  // The coordinates of the layout element
  var width = coords.xl - coords.xi
    , height = coords.yl - coords.yi
    , xi = coords.xi
    , yi = coords.yi;

  // The current row offset in cells (which row are we on?)
  var rowOffset = 0;

  // The index of the first child in the row
  var rowIndex = 0;
  var lastRowIndex = 0;

  // Figure out the highest width child
  if (this.options.layout === 'grid') {
    var highWidth = this.children.reduce(function(out, el) {
      out = Math.max(out, el.width);
      return out;
    }, 0);
  }

  return function iterator(el, i) {
    // Make our children shrinkable. If they don't have a height, for
    // example, calculate it for them.
    el.shrink = true;

    // Find the previous rendered child's coordinates
    var last = self.getLast(i);

    // If there is no previously rendered element, we are on the first child.
    if (!last) {
      el.position.left = 0;
      el.position.top = 0;
    } else {
      // Otherwise, figure out where to place this child. We'll start by
      // setting it's `left`/`x` coordinate to right after the previous
      // rendered element. This child will end up directly to the right of it.
      el.position.left = last.lpos.xl - xi;

      // Make sure the position matches the highest width element
      if (self.options.layout === 'grid') {
        // Compensate with width:
        // el.position.width = el.width + (highWidth - el.width);
        // Compensate with position:
        el.position.left += highWidth - (last.lpos.xl - last.lpos.xi);
      }

      // If our child does not overlap the right side of the Layout, set it's
      // `top`/`y` to the current `rowOffset` (the coordinate for the current
      // row).
      if (el.position.left + el.width <= width) {
        el.position.top = rowOffset;
      } else {
        // Otherwise we need to start a new row and calculate a new
        // `rowOffset` and `rowIndex` (the index of the child on the current
        // row).
        rowOffset += self.children.slice(rowIndex, i).reduce(function(out, el) {
          if (!self.isRendered(el)) return out;
          out = Math.max(out, el.lpos.yl - el.lpos.yi);
          return out;
        }, 0);
        lastRowIndex = rowIndex;
        rowIndex = i;
        el.position.left = 0;
        el.position.top = rowOffset;
      }
    }

    // Make sure the elements on lower rows graviatate up as much as possible
    if (self.options.layout === 'inline') {
      var above = null;
      var abovea = Infinity;
      for (var j = lastRowIndex; j < rowIndex; j++) {
        var l = self.children[j];
        if (!self.isRendered(l)) continue;
        var abs = Math.abs(el.position.left - (l.lpos.xi - xi));
        // if (abs < abovea && (l.lpos.xl - l.lpos.xi) <= el.width) {
        if (abs < abovea) {
          above = l;
          abovea = abs;
        }
      }
      if (above) {
        el.position.top = above.lpos.yl - yi;
      }
    }

    // If our child overflows the Layout, do not render it!
    // Disable this feature for now.
    if (el.position.top + el.height > height) {
      // Returning false tells blessed to ignore this child.
      // return false;
    }
  };
};

Layout.prototype.render = function() {
  this._emit('prerender');

  var coords = this._renderCoords();
  if (!coords) {
    delete this.lpos;
    return;
  }

  if (coords.xl - coords.xi <= 0) {
    coords.xl = Math.max(coords.xl, coords.xi);
    return;
  }

  if (coords.yl - coords.yi <= 0) {
    coords.yl = Math.max(coords.yl, coords.yi);
    return;
  }

  this.lpos = coords;

  if (this.border) coords.xi++, coords.xl--, coords.yi++, coords.yl--;
  if (this.tpadding) {
    coords.xi += this.padding.left, coords.xl -= this.padding.right;
    coords.yi += this.padding.top, coords.yl -= this.padding.bottom;
  }

  var iterator = this.renderer(coords);

  if (this.border) coords.xi--, coords.xl++, coords.yi--, coords.yl++;
  if (this.tpadding) {
    coords.xi -= this.padding.left, coords.xl += this.padding.right;
    coords.yi -= this.padding.top, coords.yl += this.padding.bottom;
  }

  this.children.forEach(function(el, i) {
    if (el.screen._ci !== -1) {
      el.index = el.screen._ci++;
    }
    var rendered = iterator(el, i);
    if (rendered === false) {
      delete el.lpos;
      return;
    }
    // if (el.screen._rendering) {
    //   el._rendering = true;
    // }
    el.render();
    // if (el.screen._rendering) {
    //   el._rendering = false;
    // }
  });

  this._emit('render', [coords]);

  return coords;
};

/**
 * Expose
 */

module.exports = Layout;