// Credit: https://github.com/iCrawl/Tohru/blob/master/src/providers/Sequelize.js

const { SettingProvider } = require('discord.js-commando');
const Sequelize = require('sequelize');

/**
 * Uses an PostgreSQL database to store settings with guilds
 * @extends {SettingProvider}
 */
class SequelizeProvider extends SettingProvider {
	/**
	 * @external PostgreSQLDatabase
	 * @see {@link https://www.npmjs.com/package/sequelize}
	 */

	/**
	 * @param {SQLDatabase} db - Database for the provider
	 */
	constructor(db) {
		super();

		/**
		 * Database that will be used for storing/retrieving settings
		 * @type {SQLDatabase}
		 */
		this.db = db;

		/**
		 * Client that the provider is for (set once the client is ready, after using {@link CommandoClient#setProvider})
		 * @name SequelizeProvider#client
		 * @type {CommandoClient}
		 * @readonly
		 */
		Object.defineProperty(this, 'client', { value: null, writable: true });

		/**
		 * Settings cached in memory, mapped by guild ID (or 'global')
		 * @type {Map}
		 * @private
		 */
		this.settings = new Map();

		/**
		 * Listeners on the Client, mapped by the event name
		 * @type {Map}
		 * @private
		 */
		this.listeners = new Map();

		/**
		 * Sequelize Model Object
		 * @type {SequelizeModel}
		 * @private
		 */
		this.model = this.db.define('settings', {
			guild: {
				type: Sequelize.BIGINT,
				allowNull: false,
				unique: true,
				primaryKey: true
			},
			settings: { type: Sequelize.TEXT }
		}, { freezeTableName: true, timestamps: false });

		/**
		 * @external SequelizeModel
		 * @see {@link http://docs.sequelizejs.com/en/latest/api/model/}
		 */
	}

	async init(client) {
		this.client = client;
		await this.db.sync();

		// Load all settings
		const rows = await this.model.findAll();
		for (const row of rows) {
			let settings;
			try {
				settings = JSON.parse(row.dataValues.settings);
			} catch (err) {
				client.emit('warn', `SequelizeProvider couldn't parse the settings stored for guild ${row.dataValues.guild}.`);
				continue;
			}

			const guild = row.dataValues.guild !== '0' ? row.dataValues.guild : 'global';

			this.settings.set(guild, settings);
			if (guild !== 'global' && !client.guilds.has(row.dataValues.guild)) continue;
			this.setupGuild(guild, settings);
		}

		// Listen for changes
		this.listeners
			.set('commandPrefixChange', (guild, prefix) => this.set(guild, 'prefix', prefix))
			.set('commandStatusChange', (guild, command, enabled) => this.set(guild, `cmd-${command.name}`, enabled))
			.set('groupStatusChange', (guild, group, enabled) => this.set(guild, `grp-${group.id}`, enabled))
			.set('guildCreate', guild => {
				const settings = this.settings.get(guild.id);
				if (!settings) return;
				this.setupGuild(guild.id, settings);
			})
			.set('commandRegister', command => {
				for (const [guild, settings] of this.settings) {
					if (guild !== 'global' && !client.guilds.has(guild)) continue;
					this.setupGuildCommand(client.guilds.get(guild), command, settings);
				}
			})
			.set('groupRegister', group => {
				for (const [guild, settings] of this.settings) {
					if (guild !== 'global' && !client.guilds.has(guild)) continue;
					this.setupGuildGroup(client.guilds.get(guild), group, settings);
				}
			});
		for (const [event, listener] of this.listeners) client.on(event, listener);
	}

	destroy() {
		// Remove all listeners from the client
		for (const [event, listener] of this.listeners) this.client.removeListener(event, listener);
		this.listeners.clear();
	}

	get(guild, key, defVal) {
		const settings = this.settings.get(this.constructor.getGuildID(guild));
		return settings ? typeof settings[key] !== 'undefined' ? settings[key] : defVal : defVal;
	}

	async set(guild, key, val) {
		guild = this.constructor.getGuildID(guild);
		let settings = this.settings.get(guild);
		if (!settings) {
			settings = {};
			this.settings.set(guild, settings);
		}

		settings[key] = val;
		await this.model.upsert(
			{ guild: guild !== 'global' ? guild : '0', settings: JSON.stringify(settings) }
		);
		if (guild === 'global') this.updateOtherShards(key, val);
		return val;
	}

	async remove(guild, key) {
		guild = this.constructor.getGuildID(guild);
		const settings = this.settings.get(guild);
		if (!settings || typeof settings[key] === 'undefined') return undefined;

		const val = settings[key];
		settings[key] = undefined;
		await this.model.upsert(
			{ guild: guild !== 'global' ? guild : '0', settings: JSON.stringify(settings) }
		);
		if (guild === 'global') this.updateOtherShards(key, undefined);
		return val;
	}

	async clear(guild) {
		guild = this.constructor.getGuildID(guild);
		if (!this.settings.has(guild)) return;
		this.settings.delete(guild);
		await this.model.destroy({ where: { guild: guild !== 'global' ? guild : '0' } });
	}

	/**
	 * Loads all settings for a guild
	 * @param {string} guild - Guild ID to load the settings of (or 'global')
	 * @param {Object} settings - Settings to load
	 * @private
	 */
	setupGuild(guild, settings) {
		if (typeof guild !== 'string') throw new TypeError('The guild must be a guild ID or "global".');
		guild = this.client.guilds.get(guild) || null;

		// Load the command prefix
		if (typeof settings.prefix !== 'undefined') {
			if (guild) guild._commandPrefix = settings.prefix;
			else this.client._commandPrefix = settings.prefix;
		}

		// Load all command/group statuses
		for (const command of this.client.registry.commands.values()) this.setupGuildCommand(guild, command, settings);
		for (const group of this.client.registry.groups.values()) this.setupGuildGroup(guild, group, settings);
	}

	/**
	 * Sets up a command's status in a guild from the guild's settings
	 * @param {?Guild} guild - Guild to set the status in
	 * @param {Command} command - Command to set the status of
	 * @param {Object} settings - Settings of the guild
	 * @private
	 */
	setupGuildCommand(guild, command, settings) {
		if (typeof settings[`cmd-${command.name}`] === 'undefined') return;
		if (guild) {
			if (!guild._commandsEnabled) guild._commandsEnabled = {};
			guild._commandsEnabled[command.name] = settings[`cmd-${command.name}`];
		} else {
			command._globalEnabled = settings[`cmd-${command.name}`];
		}
	}

	/**
	 * Sets up a group's status in a guild from the guild's settings
	 * @param {?Guild} guild - Guild to set the status in
	 * @param {CommandGroup} group - Group to set the status of
	 * @param {Object} settings - Settings of the guild
	 * @private
	 */
	setupGuildGroup(guild, group, settings) {
		if (typeof settings[`grp-${group.id}`] === 'undefined') return;
		if (guild) {
			if (!guild._groupsEnabled) guild._groupsEnabled = {};
			guild._groupsEnabled[group.id] = settings[`grp-${group.id}`];
		} else {
			group._globalEnabled = settings[`grp-${group.id}`];
		}
	}

	/**
	 * Updates a global setting on all other shards if using the {@link ShardingManager}.
	 * @param {string} key - Key of the setting to update
	 * @param {*} val - Value of the setting
	 * @private
	 */
	updateOtherShards(key, val) {
		if (!this.client.shard) return;
		key = JSON.stringify(key);
		val = typeof val !== 'undefined' ? JSON.stringify(val) : 'undefined';
		this.client.shard.broadcastEval(`
			if(this.shard.id !== ${this.client.shard.id} && this.provider && this.provider.settings) {
				let global = this.provider.settings.get('global');
				if (!global) {
					global = {};
					this.provider.settings.set('global', global)
				}
				global[${key}] = ${val};
			}
		`);
	}
}

module.exports = SequelizeProvider;