// fancy-pants parsing of argv, originally forked
// from minimist: https://www.npmjs.com/package/minimist
var camelCase = require('camelcase'),
  fs = require('fs'),
  path = require('path');

module.exports = function (args, opts) {
    if (!opts) opts = {};
    var flags = { arrays: {}, bools : {}, strings : {}, counts: {}, normalize: {}, configs: {} };

    [].concat(opts['array']).filter(Boolean).forEach(function (key) {
        flags.arrays[key] = true;
    });

    [].concat(opts['boolean']).filter(Boolean).forEach(function (key) {
        flags.bools[key] = true;
    });

    [].concat(opts.string).filter(Boolean).forEach(function (key) {
        flags.strings[key] = true;
    });

    [].concat(opts.count).filter(Boolean).forEach(function (key) {
        flags.counts[key] = true;
    });

    [].concat(opts.normalize).filter(Boolean).forEach(function (key) {
        flags.normalize[key] = true;
    });

    [].concat(opts.config).filter(Boolean).forEach(function (key) {
        flags.configs[key] = true;
    });

    var aliases = {},
        newAliases = {};

    extendAliases(opts.key);
    extendAliases(opts.alias);

    var defaults = opts['default'] || {};
    Object.keys(defaults).forEach(function (key) {
        if (/-/.test(key) && !opts.alias[key]) {
            var c = camelCase(key);
            aliases[key] = aliases[key] || [];
            // don't allow the same key to be added multiple times.
            if (aliases[key].indexOf(c) === -1) {
                aliases[key] = (aliases[key] || []).concat(c);
                newAliases[c] = true;
            }
        }
        (aliases[key] || []).forEach(function (alias) {
            defaults[alias] = defaults[key];
        });
    });

    var argv = { _ : [] };
    Object.keys(flags.bools).forEach(function (key) {
        setArg(key, !(key in defaults) ? false : defaults[key]);
    });

    var notFlags = [];
    if (args.indexOf('--') !== -1) {
        notFlags = args.slice(args.indexOf('--')+1);
        args = args.slice(0, args.indexOf('--'));
    }

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

        // -- seperated by =
        if (arg.match(/^--.+=/)) {
            // 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 (arg.match(/^--no-.+/)) {
            var key = arg.match(/^--no-(.+)/)[1];
            setArg(key, false);
        }
        // -- seperated by space.
        else if (arg.match(/^--.+/)) {
            var key = arg.match(/^--(.+)/)[1];

            if (checkAllAliases(key, opts.narg)) {
                i = eatNargs(i, key, args);
            } else {
                var next = args[i + 1];

                if (next !== undefined && !next.match(/^-/)
                    && !checkAllAliases(key, flags.bools)
                    && !checkAllAliases(key, flags.counts)) {
                    setArg(key, next);
                    i++;
                }
                else if (/^(true|false)$/.test(next)) {
                    setArg(key, next);
                    i++;
                }
                else {
                    setArg(key, defaultForType(guessType(key, flags)));
                }
            }
        }
        // dot-notation flag seperated by '='.
        else if (arg.match(/^-.\..+=/)) {
            var m = arg.match(/^-([^=]+)=([\s\S]*)$/);
            setArg(m[1], m[2]);
        }
        // dot-notation flag seperated by space.
        else if (arg.match(/^-.\..+/)) {
            var key = arg.match(/^-(.\..+)/)[1];
            var next = args[i + 1];
            if (next !== undefined && !next.match(/^-/)
                && !checkAllAliases(key, flags.bools)
                && !checkAllAliases(key, flags.counts)) {
                setArg(key, next);
                i++;
            }
            else {
                setArg(key, defaultForType(guessType(key, flags)));
            }
        }
        else if (arg.match(/^-[^-]+/)) {
            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 (letters[j+1] && letters[j+1] === '=') {
                    setArg(letters[j], arg.slice(j+3));
                    broken = true;
                    break;
                }

                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], defaultForType(guessType(letters[j], flags)));
                }
            }

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

            if (!broken && key !== '-') {
                if (checkAllAliases(key, opts.narg)) {
                    i = eatNargs(i, key, args);
                } else {
                    if (args[i+1] && !/^(-|--)[^-]/.test(args[i+1])
                        && !checkAllAliases(key, flags.bools)
                        && !checkAllAliases(key, flags.counts)) {
                        setArg(key, args[i+1]);
                        i++;
                    }
                    else if (args[i+1] && /true|false/.test(args[i+1])) {
                        setArg(key, args[i+1]);
                        i++;
                    }
                    else {
                        setArg(key, defaultForType(guessType(key, flags)));
                    }
                }
            }
        }
        else {
            argv._.push(
                flags.strings['_'] || !isNumber(arg) ? arg : Number(arg)
            );
        }
    }

    setConfig(argv);
    applyDefaultsAndAliases(argv, aliases, defaults);

    Object.keys(flags.counts).forEach(function (key) {
        setArg(key, defaults[key]);
    });

    notFlags.forEach(function(key) {
        argv._.push(key);
    });

    // how many arguments should we consume, based
    // on the nargs option?
    function eatNargs (i, key, args) {
        var toEat = checkAllAliases(key, opts.narg);

        if (args.length - (i + 1) < toEat) throw Error('not enough arguments following: ' + key);

        for (var ii = i + 1; ii < (toEat + i + 1); ii++) {
            setArg(key, args[ii]);
        }

        return (i + toEat);
    }

    function setArg (key, val) {
        // handle parsing boolean arguments --foo=true --bar false.
        if (checkAllAliases(key, flags.bools) || checkAllAliases(key, flags.counts)) {
          if (typeof val === 'string') val = val === 'true';
        }

        if (/-/.test(key) && !(aliases[key] && aliases[key].length)) {
            var c = camelCase(key);
            aliases[key] = [c];
            newAliases[c] = true;
        }

        var value = !checkAllAliases(key, flags.strings) && isNumber(val) ? Number(val) : val;

        if (checkAllAliases(key, flags.counts)) {
            value = function(orig) { return orig !== undefined ? orig + 1 : 0; };
        }

        var splitKey = key.split('.');
        setKey(argv, splitKey, value);

        (aliases[splitKey[0]] || []).forEach(function (x) {
            x = x.split('.');

            // handle populating dot notation for both
            // the key and its aliases.
            if (splitKey.length > 1) {
              var a = [].concat(splitKey);
              a.shift(); // nuke the old key.
              x = x.concat(a);
            }

            setKey(argv, x, value);
        });

        var keys = [key].concat(aliases[key] || []);
        for (var i = 0, l = keys.length; i < l; i++) {
            if (flags.normalize[keys[i]]) {
                keys.forEach(function(key) {
                    argv.__defineSetter__(key, function(v) {
                        val = path.normalize(v);
                    });

                    argv.__defineGetter__(key, function () {
                        return typeof val === 'string' ?
                            path.normalize(val) : val;
                    });
                });
                break;
            }
        }
    }

    // set args from config.json file, this should be
    // applied last so that defaults can be applied.
    function setConfig (argv) {
        var configLookup = {};

        // expand defaults/aliases, in-case any happen to reference
        // the config.json file.
        applyDefaultsAndAliases(configLookup, aliases, defaults);

        Object.keys(flags.configs).forEach(function(configKey) {
            var configPath = argv[configKey] || configLookup[configKey];
            if (configPath) {
              try {
                  var config = JSON.parse(fs.readFileSync(configPath, 'utf8'));
                  Object.keys(config).forEach(function (key) {
                      // setting arguments via CLI takes precedence over
                      // values within the config file.
                      if (argv[key] === undefined) {
                        delete argv[key];
                        setArg(key, config[key]);
                      }
                  });
              } catch (ex) {
                  throw Error('invalid json config file: ' + configPath);
              }
            }
        });
    }

    function applyDefaultsAndAliases(obj, aliases, defaults) {
        Object.keys(defaults).forEach(function (key) {
            if (!hasKey(obj, key.split('.'))) {
                setKey(obj, key.split('.'), defaults[key]);

                (aliases[key] || []).forEach(function (x) {
                    setKey(obj, x.split('.'), defaults[key]);
                });
            }
        });
    }

    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 (typeof value === 'function') {
            o[key] = value(o[key]);
        }
        else if (o[key] === undefined && checkAllAliases(key, flags.arrays)) {
            o[key] = Array.isArray(value) ? value : [value];
        }
        else 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 ];
        }
    }

    // extend the aliases list with inferred aliases.
    function extendAliases (obj) {
      Object.keys(obj || {}).forEach(function(key) {
        aliases[key] = [].concat(opts.alias[key] || []);
        // For "--option-name", also set argv.optionName
        aliases[key].concat(key).forEach(function (x) {
            if (/-/.test(x)) {
                var c = camelCase(x);
                aliases[key].push(c);
                newAliases[c] = true;
            }
        });
        aliases[key].forEach(function (x) {
            aliases[x] = [key].concat(aliases[key].filter(function (y) {
                return x !== y;
            }));
        });
      });
    }

    // check if a flag is set for any of a key's aliases.
    function checkAllAliases (key, flag) {
        var isSet = false,
          toCheck = [].concat(aliases[key] || [], key);

        toCheck.forEach(function(key) {
            if (flag[key]) isSet = flag[key];
        });

        return isSet;
    };

    // return a default value, given the type of a flag.,
    // e.g., key of type 'string' will default to '', rather than 'true'.
    function defaultForType (type) {
        var def = {
            boolean: true,
            string: '',
            array: []
        };

        return def[type];
    }

    // given a flag, enforce a default type.
    function guessType (key, flags) {
        var type = 'boolean';

        if (flags.strings && flags.strings[key]) type = 'string';
        else if (flags.arrays && flags.arrays[key]) type = 'array';

        return type;
    }

    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);
    }

    return {
        argv: argv,
        aliases: aliases,
        newAliases: newAliases
    };
};