/**
* @license
*
* Copyright 2011 Google Inc.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*     http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

/**
* @fileoverview Map Label.
*
* @author Luke Mahe (lukem@google.com),
*         Chris Broadfoot (cbro@google.com)
*/

/**
* Creates a new Map Label
* @constructor
* @extends google.maps.OverlayView
* @param {Object.<string, *>=} opt_options Optional properties to set.
*/

function MapLabel(opt_options) {
    this.set('fontFamily', 'sans-serif');
    this.set('fontSize', 12);
    this.set('fontColor', '#000000');
    this.set('strokeWeight', 3);
    this.set('strokeColor', '#E6E6E6');
    this.set('align', 'center');

    this.set('zIndex', 1e3);

    this.setValues(opt_options);
}
MapLabel.prototype = new google.maps.OverlayView;

//window['MapLabel'] = MapLabel;


/** @inheritDoc */
MapLabel.prototype.changed = function (prop) {
    switch (prop) {
        case 'fontFamily':
        case 'fontSize':
        case 'fontColor':
        case 'strokeWeight':
        case 'strokeColor':
        case 'align':
        case 'text':
            return this.drawCanvas_();
        case 'maxZoom':
        case 'minZoom':
        case 'position':
            return this.draw();
    }
};

/**
* Draws the label to the canvas 2d context.
* @private
*/
MapLabel.prototype.drawCanvas_ = function () {
    var canvas = this.canvas_;
    if (!canvas) return;

    var style = canvas.style;
    style.zIndex = /** @type number */(this.get('zIndex'));

    var ctx = canvas.getContext('2d');
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    ctx.strokeStyle = this.get('strokeColor');
    ctx.fillStyle = this.get('fontColor');
    ctx.font = this.get('fontSize') + 'px ' + this.get('fontFamily');

    var strokeWeight = Number(this.get('strokeWeight'));

    var text = this.get('text');
    ctx.id = text;
    if (text) {
        if (strokeWeight) {
            ctx.lineWidth = strokeWeight;
            ctx.strokeText(text, strokeWeight, strokeWeight);
        }

        ctx.fillText(text, strokeWeight, strokeWeight);

        var textMeasure = ctx.measureText(text);
        var textWidth = textMeasure.width + strokeWeight;
        style.marginLeft = this.getMarginLeft_(textWidth) + 'px';
        // Bring actual text top in line with desired latitude.
        // Cheaper than calculating height of text.
        style.marginTop = '-0.4em';
    }
};

/**
* @inheritDoc
*/
MapLabel.prototype.onAdd = function () {
    var canvas = this.canvas_ = document.createElement('canvas');
    var style = canvas.style;
    style.position = 'absolute';

    var ctx = canvas.getContext('2d');
    ctx.lineJoin = 'round';
    ctx.textBaseline = 'top';

    this.drawCanvas_();

    var panes = this.getPanes();
    if (panes) {
        panes.overlayLayer.appendChild(canvas);
        /*
        var tmp = "";
        for (i = 0; i < panes.overlayLayer.children.length - 1; i++) {
        tmp += panes.overlayLayer.children[i].id;
        }
        //alert(tmp);
        */
    }
    //alert(panes.overlayLayer.children.length);
};
MapLabel.prototype['onAdd'] = MapLabel.prototype.onAdd;

/**
* Gets the appropriate margin-left for the canvas.
* @private
* @param {number} textWidth  the width of the text, in pixels.
* @return {number} the margin-left, in pixels.
*/
MapLabel.prototype.getMarginLeft_ = function (textWidth) {
    switch (this.get('align')) {
        case 'left':
            return 0;
        case 'right':
            return -textWidth;
    }
    return textWidth / -2;
};

/**
* @inheritDoc
*/
MapLabel.prototype.draw = function () {
    var projection = this.getProjection();

    if (!projection) {
        // The map projection is not ready yet so do nothing
        return;
    }

    if (!this.canvas_) {
        // onAdd has not been called yet.
        return;
    }

    var latLng = /** @type {google.maps.LatLng} */(this.get('position'));
    if (!latLng) {
        return;
    }
    var pos = projection.fromLatLngToDivPixel(latLng);

    var style = this.canvas_.style;

    style['top'] = pos.y + 'px';
    style['left'] = pos.x + 'px';

    if (this.getVisible_() == "") {
        if (g_displayLabel)
            this.Show();
        else
            this.Hide();
    }
    else
        this.Hide();
};
MapLabel.prototype['draw'] = MapLabel.prototype.draw;

MapLabel.prototype.Hide = function () {
    var style = this.canvas_.style;
    style['visibility'] = "hidden";
};

MapLabel.prototype.Show = function () {
    var style = this.canvas_.style;
    style['visibility'] = "";
};



/**
* Get the visibility of the label.
* @private
* @return {string} blank string if visible, 'hidden' if invisible.
*/
MapLabel.prototype.getVisible_ = function () {
    var minZoom = /** @type number */(this.get('minZoom'));
    var maxZoom = /** @type number */(this.get('maxZoom'));

    if (minZoom === undefined && maxZoom === undefined) {
        return '';
    }

    var map = this.getMap();
    if (!map) {
        return '';
    }

    var mapZoom = map.getZoom();
    if (mapZoom < minZoom || mapZoom > maxZoom) {
        return 'hidden';
    }
    return '';
};

/**
* @inheritDoc
*/
MapLabel.prototype.onRemove = function () {
    var canvas = this.canvas_;
    if (canvas && canvas.parentNode) {
        canvas.parentNode.removeChild(canvas);
    }
};
MapLabel.prototype['onRemove'] = MapLabel.prototype.onRemove;