HORIZON PROJECT

module.exports = function (args, opts) {

    if (!opts) opts = {};

    var flags = { bools : {}, strings : {} };

    [].concat(opts['boolean']).filter(Boolean).forEach(function (key) {

        flags.bools[key] = true;

    });

    [].concat(opts.string).filter(Boolean).forEach(function (key) {

        flags.strings[key] = true;

    });

    var aliases = {};

    Object.keys(opts.alias || {}).forEach(function (key) {

        aliases[key] = [].concat(opts.alias[key]);

        aliases[key].forEach(function (x) {

            aliases[x] = [key].concat(aliases[key].filter(function (y) {

                return x !== y;

            }));

        });

    });

    var defaults = opts['default'] || {};

    var argv = { _ : [] };

    Object.keys(flags.bools).forEach(function (key) {

        setArg(key, defaults[key] === undefined ? false : defaults[key]);

    });

    var notFlags = [];

    if (args.indexOf('--') !== -1) {

        notFlags = args.slice(args.indexOf('--')+1);

        args = args.slice(0, args.indexOf('--'));

    }

    function setArg (key, val) {

        var value = !flags.strings[key] && isNumber(val)

            ? Number(val) : val

        ;

        setKey(argv, key.split('.'), value);

        (aliases[key] || []).forEach(function (x) {

            setKey(argv, x.split('.'), value);

        });

    }

    for (var i = 0; i < args.length; i++) {

        var arg = args[i];

        if (/^--.+=/.test(arg)) {

            // Using [\s\S] instead of . because js doesn't support the

            // 'dotall' regex modifier. See:

            // http://stackoverflow.com/a/1068308/13216

            var m = arg.match(/^--([^=]+)=([\s\S]*)$/);

            setArg(m[1], m[2]);

        }

        else if (/^--no-.+/.test(arg)) {

            var key = arg.match(/^--no-(.+)/)[1];

            setArg(key, false);

        }

        else if (/^--.+/.test(arg)) {

            var key = arg.match(/^--(.+)/)[1];

            var next = args[i + 1];

            if (next !== undefined && !/^-/.test(next)

            && !flags.bools[key]

            && (aliases[key] ? !flags.bools[aliases[key]] : true)) {

                setArg(key, next);

                i++;

            }

            else if (/^(true|false)$/.test(next)) {

                setArg(key, next === 'true');

                i++;

            }

            else {

                setArg(key, flags.strings[key] ? '' : true);

            }

        }

        else if (/^-[^-]+/.test(arg)) {

            var letters = arg.slice(1,-1).split('');

            var broken = false;

            for (var j = 0; j < letters.length; j++) {

                var next = arg.slice(j+2);

                if (next === '-') {

                    setArg(letters[j], next)

                    continue;

                }

                if (/[A-Za-z]/.test(letters[j])

                && /-?\d+(\.\d*)?(e-?\d+)?$/.test(next)) {

                    setArg(letters[j], next);

                    broken = true;

                    break;

                }

                if (letters[j+1] && letters[j+1].match(/\W/)) {

                    setArg(letters[j], arg.slice(j+2));

                    broken = true;

                    break;

                }

                else {

                    setArg(letters[j], flags.strings[letters[j]] ? '' : true);

                }

            }

            var key = arg.slice(-1)[0];

            if (!broken && key !== '-') {

                if (args[i+1] && !/^(-|--)[^-]/.test(args[i+1])

                && !flags.bools[key]

                && (aliases[key] ? !flags.bools[aliases[key]] : true)) {

                    setArg(key, args[i+1]);

                    i++;

                }

                else if (args[i+1] && /true|false/.test(args[i+1])) {

                    setArg(key, args[i+1] === 'true');

                    i++;

                }

                else {

                    setArg(key, flags.strings[key] ? '' : true);

                }

            }

        }

        else {

            argv._.push(

                flags.strings['_'] || !isNumber(arg) ? arg : Number(arg)

            );

        }

    }

    Object.keys(defaults).forEach(function (key) {

        if (!hasKey(argv, key.split('.'))) {

            setKey(argv, key.split('.'), defaults[key]);

            (aliases[key] || []).forEach(function (x) {

                setKey(argv, x.split('.'), defaults[key]);

            });

        }

    });

    notFlags.forEach(function(key) {

        argv._.push(key);

    });

    return argv;

};

function hasKey (obj, keys) {

    var o = obj;

    keys.slice(0,-1).forEach(function (key) {

        o = (o[key] || {});

    });

    var key = keys[keys.length - 1];

    return key in o;

}

function setKey (obj, keys, value) {

    var o = obj;

    keys.slice(0,-1).forEach(function (key) {

        if (o[key] === undefined) o[key] = {};

        o = o[key];

    });

    var key = keys[keys.length - 1];

    if (o[key] === undefined || typeof o[key] === 'boolean') {

        o[key] = value;

    }

    else if (Array.isArray(o[key])) {

        o[key].push(value);

    }

    else {

        o[key] = [ o[key], value ];

    }

}

function isNumber (x) {

    if (typeof x === 'number') return true;

    if (/^0x[0-9a-f]+$/i.test(x)) return true;

    return /^[-+]?(?:\d+(?:\.\d*)?|\.\d+)(e[-+]?\d+)?$/.test(x);

}

function longest (xs) {

    return Math.max.apply(null, xs.map(function (x) { return x.length }));

}