'use strict';

var Utils = require('./utils');

var arrayPrefixGenerators = {

brackets: function brackets(prefix) {
    return prefix + '[]';
},
indices: function indices(prefix, key) {
    return prefix + '[' + key + ']';
},
repeat: function repeat(prefix) {
    return prefix;
}

};

var defaults = {

delimiter: '&',
strictNullHandling: false,
skipNulls: false,
encode: true,
encoder: Utils.encode

};

var stringify = function stringify(object, prefix, generateArrayPrefix, strictNullHandling, skipNulls, encoder, filter, sort, allowDots) {

var obj = object;
if (typeof filter === 'function') {
    obj = filter(prefix, obj);
} else if (obj instanceof Date) {
    obj = obj.toISOString();
} else if (obj === null) {
    if (strictNullHandling) {
        return encoder ? encoder(prefix) : prefix;
    }

    obj = '';
}

if (typeof obj === 'string' || typeof obj === 'number' || typeof obj === 'boolean' || Utils.isBuffer(obj)) {
    if (encoder) {
        return [encoder(prefix) + '=' + encoder(obj)];
    }
    return [prefix + '=' + String(obj)];
}

var values = [];

if (typeof obj === 'undefined') {
    return values;
}

var objKeys;
if (Array.isArray(filter)) {
    objKeys = filter;
} else {
    var keys = Object.keys(obj);
    objKeys = sort ? keys.sort(sort) : keys;
}

for (var i = 0; i < objKeys.length; ++i) {
    var key = objKeys[i];

    if (skipNulls && obj[key] === null) {
        continue;
    }

    if (Array.isArray(obj)) {
        values = values.concat(stringify(obj[key], generateArrayPrefix(prefix, key), generateArrayPrefix, strictNullHandling, skipNulls, encoder, filter, sort, allowDots));
    } else {
        values = values.concat(stringify(obj[key], prefix + (allowDots ? '.' + key : '[' + key + ']'), generateArrayPrefix, strictNullHandling, skipNulls, encoder, filter, sort, allowDots));
    }
}

return values;

};

module.exports = function (object, opts) {

var obj = object;
var options = opts || {};
var delimiter = typeof options.delimiter === 'undefined' ? defaults.delimiter : options.delimiter;
var strictNullHandling = typeof options.strictNullHandling === 'boolean' ? options.strictNullHandling : defaults.strictNullHandling;
var skipNulls = typeof options.skipNulls === 'boolean' ? options.skipNulls : defaults.skipNulls;
var encode = typeof options.encode === 'boolean' ? options.encode : defaults.encode;
var encoder = encode ? (typeof options.encoder === 'function' ? options.encoder : defaults.encoder) : null;
var sort = typeof options.sort === 'function' ? options.sort : null;
var allowDots = typeof options.allowDots === 'undefined' ? false : options.allowDots;
var objKeys;
var filter;

if (options.encoder !== null && options.encoder !== undefined && typeof options.encoder !== 'function') {
    throw new TypeError('Encoder has to be a function.');
}

if (typeof options.filter === 'function') {
    filter = options.filter;
    obj = filter('', obj);
} else if (Array.isArray(options.filter)) {
    objKeys = filter = options.filter;
}

var keys = [];

if (typeof obj !== 'object' || obj === null) {
    return '';
}

var arrayFormat;
if (options.arrayFormat in arrayPrefixGenerators) {
    arrayFormat = options.arrayFormat;
} else if ('indices' in options) {
    arrayFormat = options.indices ? 'indices' : 'repeat';
} else {
    arrayFormat = 'indices';
}

var generateArrayPrefix = arrayPrefixGenerators[arrayFormat];

if (!objKeys) {
    objKeys = Object.keys(obj);
}

if (sort) {
    objKeys.sort(sort);
}

for (var i = 0; i < objKeys.length; ++i) {
    var key = objKeys[i];

    if (skipNulls && obj[key] === null) {
        continue;
    }

    keys = keys.concat(stringify(obj[key], key, generateArrayPrefix, strictNullHandling, skipNulls, encoder, filter, sort, allowDots));
}

return keys.join(delimiter);

};