import LockHandler, { LockType } from './LockHandler';
import { Dirnames } from './utils/types';
const BaseService = require('lib/services/BaseService.js');

// To add a new migration:
// - Add the migration logic in ./migrations/VERSION_NUM.js
// - Add the file to the array below.
// - Set Setting.syncVersion to VERSION_NUM in models/Setting.js
// - Add tests in synchronizer_migrationHandler
const migrations = [
	null,
	require('./migrations/1.js').default,
	require('./migrations/2.js').default,
];

const Setting = require('lib/models/Setting');
const { sprintf } = require('sprintf-js');
const JoplinError = require('lib/JoplinError');

interface SyncTargetInfo {
	version: number,
}

export default class MigrationHandler extends BaseService {

	private api_:any = null;
	private lockHandler_:LockHandler = null;
	private clientType_:string;
	private clientId_:string;

	constructor(api:any, lockHandler:LockHandler, clientType:string, clientId:string) {
		super();
		this.api_ = api;
		this.lockHandler_ = lockHandler;
		this.clientType_ = clientType;
		this.clientId_ = clientId;
	}

	public async fetchSyncTargetInfo():Promise<SyncTargetInfo> {
		const syncTargetInfoText = await this.api_.get('info.json');

		// Returns version 0 if the sync target is empty
		let output:SyncTargetInfo = { version: 0 };

		if (syncTargetInfoText) {
			output = JSON.parse(syncTargetInfoText);
			if (!output.version) throw new Error('Missing "version" field in info.json');
		} else {
			const oldVersion = await this.api_.get('.sync/version.txt');
			if (oldVersion) output = { version: 1 };
		}

		return output;
	}

	private serializeSyncTargetInfo(info:SyncTargetInfo) {
		return JSON.stringify(info);
	}

	async checkCanSync():Promise<SyncTargetInfo> {
		const supportedSyncTargetVersion = Setting.value('syncVersion');
		const syncTargetInfo = await this.fetchSyncTargetInfo();

		if (syncTargetInfo.version) {
			if (syncTargetInfo.version > supportedSyncTargetVersion) {
				throw new JoplinError(sprintf('Sync version of the target (%d) is greater than the version supported by the client (%d). Please upgrade your client.', syncTargetInfo.version, supportedSyncTargetVersion), 'outdatedClient');
			} else if (syncTargetInfo.version < supportedSyncTargetVersion) {
				throw new JoplinError(sprintf('Sync version of the target (%d) is lower than the version supported by the client (%d). Please upgrade the sync target.', syncTargetInfo.version, supportedSyncTargetVersion), 'outdatedSyncTarget');
			}
		}

		return syncTargetInfo;
	}

	async upgrade(targetVersion:number = 0) {
		const supportedSyncTargetVersion = Setting.value('syncVersion');
		const syncTargetInfo = await this.fetchSyncTargetInfo();

		if (syncTargetInfo.version > supportedSyncTargetVersion) {
			throw new JoplinError(sprintf('Sync version of the target (%d) is greater than the version supported by the client (%d). Please upgrade your client.', syncTargetInfo.version, supportedSyncTargetVersion), 'outdatedClient');
		}

		// if (supportedSyncTargetVersion !== migrations.length - 1) {
		// 	// Sanity check - it means a migration has been added by syncVersion has not be incremented or vice-versa,
		// 	// so abort as it can cause strange issues.
		// 	throw new JoplinError('Application error: mismatch between max supported sync version and max migration number: ' + supportedSyncTargetVersion + ' / ' + (migrations.length - 1));
		// }

		// Special case for version 1 because it didn't have the lock folder and without
		// it the lock handler will break. So we create the directory now.
		// Also if the sync target version is 0, it means it's a new one so we need the
		// lock folder first before doing anything else.
		if (syncTargetInfo.version === 0 || syncTargetInfo.version === 1) {
			this.logger().info('MigrationHandler: Sync target version is 0 or 1 - creating "locks" directory:', syncTargetInfo);
			await this.api_.mkdir(Dirnames.Locks);
		}

		this.logger().info('MigrationHandler: Acquiring exclusive lock');
		const exclusiveLock = await this.lockHandler_.acquireLock(LockType.Exclusive, this.clientType_, this.clientId_, 1000 * 30);
		let autoLockError = null;
		this.lockHandler_.startAutoLockRefresh(exclusiveLock, (error:any) => {
			autoLockError = error;
		});

		this.logger().info('MigrationHandler: Acquired exclusive lock:', exclusiveLock);

		try {
			for (let newVersion = syncTargetInfo.version + 1; newVersion < migrations.length; newVersion++) {
				if (targetVersion && newVersion > targetVersion) break;

				const fromVersion = newVersion - 1;

				this.logger().info(`MigrationHandler: Migrating from version ${fromVersion} to version ${newVersion}`);

				const migration = migrations[newVersion];
				if (!migration) continue;

				try {
					if (autoLockError) throw autoLockError;
					await migration(this.api_);
					if (autoLockError) throw autoLockError;

					await this.api_.put('info.json', this.serializeSyncTargetInfo({
						...syncTargetInfo,
						version: newVersion,
					}));

					this.logger().info(`MigrationHandler: Done migrating from version ${fromVersion} to version ${newVersion}`);
				} catch (error) {
					error.message = `Could not upgrade from version ${fromVersion} to version ${newVersion}: ${error.message}`;
					throw error;
				}
			}
		} finally {
			this.logger().info('MigrationHandler: Releasing exclusive lock');
			this.lockHandler_.stopAutoLockRefresh(exclusiveLock);
			await this.lockHandler_.releaseLock(LockType.Exclusive, this.clientType_, this.clientId_);
		}
	}

}