/**
 * The MIT License (MIT)
 * 
 * Copyright (c) 2015 Jordan Thomas
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 */

"use strict";

var jaro_winkler = function(a, b, options)
{
    // Load default options
    options = optionDefault(
        {
            "caseSensitive" : true
        },
        options
    );

    // Convert to lowercase if not case-sensitive
    if(!options.caseSensitive)
    {
        a = a.toLowerCase();
        b = b.toLowerCase();
    }


    var alen = a.length,
        blen = b.length;

    // Short-circuit if either is empty
    if(alen === 0 || blen === 0)
    {
        return 0;
    }

    // Short-circuit if exact match
    if(a === b)
    {
        return 1;
    }


    // Calculate difference
    var i, j;
    var low, high,
        m = 0,
        range = (Math.floor(Math.max(alen, blen) / 2)) - 1,
        aMatches = [],
        bMatches = [];

    // Find matches
    for(i = 0; i < alen; i++)
    {
        low  = ((i >= range) ? i - range : 0);
        high = ((i + range <= blen) ? (i + range) : (blen - 1));

        for(j = low; j <= high; j++)
        {
            if(aMatches[i] !== true && bMatches[j] !== true && a[i] === b[j])
            {
                aMatches[i] = true;
                bMatches[j] = true;
                m++;
                break;
            }
        }
    }

    // Short-circuit if not matches found
    if(m === 0)
    {
        return 0;
    }

    // Count transpositions
    var k = 0,
        numTrans = 0;

    for(i = 0; i < alen; i++)
    {
        if(aMatches[i] === true)
        {
            for(j = k; j < blen; j++)
            {
                if(bMatches[j] === true)
                {
                    k = j + 1;
                    break;
                }
            }

            if(a[i] !== b[j])
            {
                numTrans++;
            }
        }
    }

    var weight = (((m / alen) + (m / blen) + (m - (numTrans / 2)) / m) / 3);
    var l = 0,
        p = 0.1;

    if(weight > 0.7)
    {
        while(a[l] === b[l] && l < 4)
        {
            l++;
        }

        weight += l * p * (1 - weight);
    }

    return weight;
};