import isArray from '../utils/is-array';
import isUndefined from '../utils/is-undefined';
import { deprecateSimple } from '../utils/deprecate';
import { mergeConfigs } from './set';
import { Locale } from './constructor';
import keys from '../utils/keys';

import { baseConfig } from './base-config';

// internal storage for locale config files
var locales = {},
    localeFamilies = {},
    globalLocale;

function commonPrefix(arr1, arr2) {
    var i,
        minl = Math.min(arr1.length, arr2.length);
    for (i = 0; i < minl; i += 1) {
        if (arr1[i] !== arr2[i]) {
            return i;
        }
    }
    return minl;
}

function normalizeLocale(key) {
    return key ? key.toLowerCase().replace('_', '-') : key;
}

// pick the locale from the array
// try ['en-au', 'en-gb'] as 'en-au', 'en-gb', 'en', as in move through the list trying each
// substring from most specific to least, but move to the next array item if it's a more specific variant than the current root
function chooseLocale(names) {
    var i = 0,
        j,
        next,
        locale,
        split;

    while (i < names.length) {
        split = normalizeLocale(names[i]).split('-');
        j = split.length;
        next = normalizeLocale(names[i + 1]);
        next = next ? next.split('-') : null;
        while (j > 0) {
            locale = loadLocale(split.slice(0, j).join('-'));
            if (locale) {
                return locale;
            }
            if (
                next &&
                next.length >= j &&
                commonPrefix(split, next) >= j - 1
            ) {
                //the next array item is better than a shallower substring of this one
                break;
            }
            j--;
        }
        i++;
    }
    return globalLocale;
}

function isLocaleNameSane(name) {
    // Prevent names that look like filesystem paths, i.e contain '/' or '\'
    return name.match('^[^/\\\\]*$') != null;
}

function loadLocale(name) {
    var oldLocale = null,
        aliasedRequire;
    // TODO: Find a better way to register and load all the locales in Node
    if (
        locales[name] === undefined &&
        typeof module !== 'undefined' &&
        module &&
        module.exports &&
        isLocaleNameSane(name)
    ) {
        try {
            oldLocale = globalLocale._abbr;
            aliasedRequire = require;
            aliasedRequire('./locale/' + name);
            getSetGlobalLocale(oldLocale);
        } catch (e) {
            // mark as not found to avoid repeating expensive file require call causing high CPU
            // when trying to find en-US, en_US, en-us for every format call
            locales[name] = null; // null means not found
        }
    }
    return locales[name];
}

// This function will load locale and then set the global locale.  If
// no arguments are passed in, it will simply return the current global
// locale key.
export function getSetGlobalLocale(key, values) {
    var data;
    if (key) {
        if (isUndefined(values)) {
            data = getLocale(key);
        } else {
            data = defineLocale(key, values);
        }

        if (data) {
            // moment.duration._locale = moment._locale = data;
            globalLocale = data;
        } else {
            if (typeof console !== 'undefined' && console.warn) {
                //warn user if arguments are passed but the locale could not be set
                console.warn(
                    'Locale ' + key + ' not found. Did you forget to load it?'
                );
            }
        }
    }

    return globalLocale._abbr;
}

export function defineLocale(name, config) {
    if (config !== null) {
        var locale,
            parentConfig = baseConfig;
        config.abbr = name;
        if (locales[name] != null) {
            deprecateSimple(
                'defineLocaleOverride',
                'use moment.updateLocale(localeName, config) to change ' +
                    'an existing locale. moment.defineLocale(localeName, ' +
                    'config) should only be used for creating a new locale ' +
                    'See http://momentjs.com/guides/#/warnings/define-locale/ for more info.'
            );
            parentConfig = locales[name]._config;
        } else if (config.parentLocale != null) {
            if (locales[config.parentLocale] != null) {
                parentConfig = locales[config.parentLocale]._config;
            } else {
                locale = loadLocale(config.parentLocale);
                if (locale != null) {
                    parentConfig = locale._config;
                } else {
                    if (!localeFamilies[config.parentLocale]) {
                        localeFamilies[config.parentLocale] = [];
                    }
                    localeFamilies[config.parentLocale].push({
                        name: name,
                        config: config,
                    });
                    return null;
                }
            }
        }
        locales[name] = new Locale(mergeConfigs(parentConfig, config));

        if (localeFamilies[name]) {
            localeFamilies[name].forEach(function (x) {
                defineLocale(x.name, x.config);
            });
        }

        // backwards compat for now: also set the locale
        // make sure we set the locale AFTER all child locales have been
        // created, so we won't end up with the child locale set.
        getSetGlobalLocale(name);

        return locales[name];
    } else {
        // useful for testing
        delete locales[name];
        return null;
    }
}

export function updateLocale(name, config) {
    if (config != null) {
        var locale,
            tmpLocale,
            parentConfig = baseConfig;

        if (locales[name] != null && locales[name].parentLocale != null) {
            // Update existing child locale in-place to avoid memory-leaks
            locales[name].set(mergeConfigs(locales[name]._config, config));
        } else {
            // MERGE
            tmpLocale = loadLocale(name);
            if (tmpLocale != null) {
                parentConfig = tmpLocale._config;
            }
            config = mergeConfigs(parentConfig, config);
            if (tmpLocale == null) {
                // updateLocale is called for creating a new locale
                // Set abbr so it will have a name (getters return
                // undefined otherwise).
                config.abbr = name;
            }
            locale = new Locale(config);
            locale.parentLocale = locales[name];
            locales[name] = locale;
        }

        // backwards compat for now: also set the locale
        getSetGlobalLocale(name);
    } else {
        // pass null for config to unupdate, useful for tests
        if (locales[name] != null) {
            if (locales[name].parentLocale != null) {
                locales[name] = locales[name].parentLocale;
                if (name === getSetGlobalLocale()) {
                    getSetGlobalLocale(name);
                }
            } else if (locales[name] != null) {
                delete locales[name];
            }
        }
    }
    return locales[name];
}

// returns locale data
export function getLocale(key) {
    var locale;

    if (key && key._locale && key._locale._abbr) {
        key = key._locale._abbr;
    }

    if (!key) {
        return globalLocale;
    }

    if (!isArray(key)) {
        //short-circuit everything else
        locale = loadLocale(key);
        if (locale) {
            return locale;
        }
        key = [key];
    }

    return chooseLocale(key);
}

export function listLocales() {
    return keys(locales);
}