(function (root, factory) {
    var settingsApi = root && root.TaberebaSettings;
    if (typeof module === 'object' && module.exports) {
        settingsApi = require('./settings.js');
    }
    var api = factory(settingsApi);
    if (typeof module === 'object' && module.exports) {
        module.exports = api;
    }
    if (root) {
        root.TaberebaSettingsFile = api;
    }
}(typeof window !== 'undefined' ? window : globalThis, function (settingsApi) {
    'use strict';

    var maxFileBytes = 1024 * 1024;
    var settingsKey = 'tabereba_settings_v1';
    var backupKey = 'tabereba_settings_v1_before_file_import';
    var appStorageKeys = [settingsKey, backupKey,
        'tabereba_settings_v1_before_legacy_migration',
        'tabereba_history_v1', 'tabereba_hero_dismissed_v1'];

    function normalize(value) {
        if (!settingsApi || !value || typeof value !== 'object'
            || value.service !== 'tabereba' || value.schema_version !== 1
            || value.version !== 1 || !Array.isArray(value.sites)
            || value.sites.length < 1 || value.sites.length > 20) {
            return null;
        }
        return settingsApi.normalizeSettings(value);
    }

    function parse(json) {
        if (typeof json !== 'string' || json.length < 1 || json.length > maxFileBytes) {
            return {success: false, error: 'size', settings: null, summary: null};
        }
        try {
            var settings = normalize(JSON.parse(json));
            if (!settings) {
                return {success: false, error: 'schema', settings: null, summary: null};
            }
            var affiliateEntries = 0;
            var affiliateSites = settings.sites.filter(function (site) {
                var count = ['hotpepper_valuecommerce_html', 'tabelog_valuecommerce_html',
                    'gnavi_linkshare_html'].filter(function (key) { return site[key] !== ''; }).length;
                affiliateEntries += count;
                return count > 0;
            }).length;
            return {success: true, error: '', settings: settings,
                summary: {site_count: settings.sites.length,
                    affiliate_site_count: affiliateSites, affiliate_entry_count: affiliateEntries}};
        } catch (error) {
            return {success: false, error: 'json', settings: null, summary: null};
        }
    }

    function writeAndVerify(storage, key, value) {
        storage.setItem(key, value);
        return storage.getItem(key) === value;
    }

    function applyToStorage(storage, nextSettings) {
        var next = normalize(nextSettings);
        var current;
        if (!next) {
            return {success: false, error: 'next_invalid'};
        }
        try {
            current = parse(storage.getItem(settingsKey) || '');
            if (!current.success) {
                return {success: false, error: 'current_invalid'};
            }
            if (!writeAndVerify(storage, backupKey, JSON.stringify(current.settings))) {
                return {success: false, error: 'backup_failed'};
            }
            if (!writeAndVerify(storage, settingsKey, JSON.stringify(next))) {
                return {success: false, error: 'settings_failed'};
            }
            return {success: true, error: ''};
        } catch (error) {
            return {success: false, error: 'storage_failed'};
        }
    }

    function restoreFromStorage(storage) {
        try {
            var backup = parse(storage.getItem(backupKey) || '');
            if (!backup.success) {
                return {success: false, error: 'backup_invalid'};
            }
            if (!writeAndVerify(storage, settingsKey, JSON.stringify(backup.settings))) {
                return {success: false, error: 'settings_failed'};
            }
            storage.removeItem(backupKey);
            return {success: storage.getItem(backupKey) === null,
                error: storage.getItem(backupKey) === null ? '' : 'backup_remove_failed'};
        } catch (error) {
            return {success: false, error: 'storage_failed'};
        }
    }

    function resetStorage(storage) {
        try {
            appStorageKeys.forEach(function (key) { storage.removeItem(key); });
            return {success: appStorageKeys.every(function (key) { return storage.getItem(key) === null; })};
        } catch (error) {
            return {success: false};
        }
    }

    return {maxFileBytes: maxFileBytes, settingsKey: settingsKey, backupKey: backupKey,
        appStorageKeys: appStorageKeys.slice(), normalize: normalize, parse: parse,
        applyToStorage: applyToStorage, restoreFromStorage: restoreFromStorage,
        resetStorage: resetStorage};
}));