import { Driver } from "../driver/Driver"
import { Repository } from "../repository/Repository"
import { EntitySubscriberInterface } from "../subscriber/EntitySubscriberInterface"
import { EntityTarget } from "../common/EntityTarget"
import { ObjectType } from "../common/ObjectType"
import { EntityManager } from "../entity-manager/EntityManager"
import { DefaultNamingStrategy } from "../naming-strategy/DefaultNamingStrategy"
import {
    CannotConnectAlreadyConnectedError,
    CannotExecuteNotConnectedError,
    EntityMetadataNotFoundError,
    QueryRunnerProviderAlreadyReleasedError,
    TypeORMError,
} from "../error"
import { TreeRepository } from "../repository/TreeRepository"
import { NamingStrategyInterface } from "../naming-strategy/NamingStrategyInterface"
import { EntityMetadata } from "../metadata/EntityMetadata"
import { Logger } from "../logger/Logger"
import { MigrationInterface } from "../migration/MigrationInterface"
import { MigrationExecutor } from "../migration/MigrationExecutor"
import { Migration } from "../migration/Migration"
import { MongoRepository } from "../repository/MongoRepository"
import { MongoEntityManager } from "../entity-manager/MongoEntityManager"
import { EntityMetadataValidator } from "../metadata-builder/EntityMetadataValidator"
import { DataSourceOptions } from "./DataSourceOptions"
import { EntityManagerFactory } from "../entity-manager/EntityManagerFactory"
import { DriverFactory } from "../driver/DriverFactory"
import { ConnectionMetadataBuilder } from "../connection/ConnectionMetadataBuilder"
import { QueryRunner } from "../query-runner/QueryRunner"
import { SelectQueryBuilder } from "../query-builder/SelectQueryBuilder"
import { LoggerFactory } from "../logger/LoggerFactory"
import { QueryResultCacheFactory } from "../cache/QueryResultCacheFactory"
import { QueryResultCache } from "../cache/QueryResultCache"
import { SqljsEntityManager } from "../entity-manager/SqljsEntityManager"
import { RelationLoader } from "../query-builder/RelationLoader"
import { ObjectUtils } from "../util/ObjectUtils"
import { IsolationLevel } from "../driver/types/IsolationLevel"
import { ReplicationMode } from "../driver/types/ReplicationMode"
import { RelationIdLoader } from "../query-builder/RelationIdLoader"
import { DriverUtils } from "../driver/DriverUtils"
import { InstanceChecker } from "../util/InstanceChecker"
import { ObjectLiteral } from "../common/ObjectLiteral"

/**
 * DataSource is a pre-defined connection configuration to a specific database.
 * You can have multiple data sources connected (with multiple connections in it),
 * connected to multiple databases in your application.
 *
 * Before, it was called `Connection`, but now `Connection` is deprecated
 * because `Connection` isn't the best name for what it's actually is.
 */
export class DataSource {
    static MetadataCache: Map<string, EntityMetadata[]> = new Map()

    readonly "@instanceof" = Symbol.for("DataSource")

    // -------------------------------------------------------------------------
    // Public Readonly Properties
    // -------------------------------------------------------------------------

    /**
     * Connection name.
     *
     * @deprecated we don't need names anymore since we are going to drop all related methods relying on this property.
     */
    readonly name: string

    /**
     * Connection options.
     */
    readonly options: DataSourceOptions

    /**
     * Indicates if DataSource is initialized or not.
     */
    readonly isInitialized: boolean

    /**
     * Database driver used by this connection.
     */
    driver: Driver

    /**
     * EntityManager of this connection.
     */
    readonly manager: EntityManager

    /**
     * Naming strategy used in the connection.
     */
    namingStrategy: NamingStrategyInterface

    /**
     * Name for the metadata table
     */
    readonly metadataTableName: string

    /**
     * Logger used to log orm events.
     */
    logger: Logger

    /**
     * Migration instances that are registered for this connection.
     */
    readonly migrations: MigrationInterface[] = []

    /**
     * Entity subscriber instances that are registered for this connection.
     */
    readonly subscribers: EntitySubscriberInterface<any>[] = []

    /**
     * All entity metadatas that are registered for this connection.
     */
    readonly entityMetadatas: EntityMetadata[] = []

    /**
     * All entity metadatas that are registered for this connection.
     * This is a copy of #.entityMetadatas property -> used for more performant searches.
     */
    readonly entityMetadatasMap = new Map<EntityTarget<any>, EntityMetadata>()

    /**
     * Used to work with query result cache.
     */
    queryResultCache?: QueryResultCache

    /**
     * Used to load relations and work with lazy relations.
     */
    readonly relationLoader: RelationLoader

    readonly relationIdLoader: RelationIdLoader

    // -------------------------------------------------------------------------
    // Constructor
    // -------------------------------------------------------------------------

    constructor(options: DataSourceOptions) {
        this.name = options.name || "default"
        this.options = options
        this.logger = new LoggerFactory().create(
            this.options.logger,
            this.options.logging,
        )
        this.driver = new DriverFactory().create(this)
        this.manager = this.createEntityManager()
        this.namingStrategy =
            options.namingStrategy || new DefaultNamingStrategy()
        this.metadataTableName = options.metadataTableName || "typeorm_metadata"
        this.queryResultCache = options.cache
            ? new QueryResultCacheFactory(this).create()
            : undefined
        this.relationLoader = new RelationLoader(this)
        this.relationIdLoader = new RelationIdLoader(this)
        this.isInitialized = false
    }

    // -------------------------------------------------------------------------
    // Public Accessors
    // -------------------------------------------------------------------------

    /**
     Indicates if DataSource is initialized or not.
     *
     * @deprecated use .isInitialized instead
     */
    get isConnected() {
        return this.isInitialized
    }

    /**
     * Gets the mongodb entity manager that allows to perform mongodb-specific repository operations
     * with any entity in this connection.
     *
     * Available only in mongodb connections.
     */
    get mongoManager(): MongoEntityManager {
        if (!InstanceChecker.isMongoEntityManager(this.manager))
            throw new TypeORMError(
                `MongoEntityManager is only available for MongoDB databases.`,
            )

        return this.manager as MongoEntityManager
    }

    /**
     * Gets a sql.js specific Entity Manager that allows to perform special load and save operations
     *
     * Available only in connection with the sqljs driver.
     */
    get sqljsManager(): SqljsEntityManager {
        if (!InstanceChecker.isSqljsEntityManager(this.manager))
            throw new TypeORMError(
                `SqljsEntityManager is only available for Sqljs databases.`,
            )

        return this.manager
    }

    // -------------------------------------------------------------------------
    // Public Methods
    // -------------------------------------------------------------------------
    /**
     * Updates current connection options with provided options.
     */
    setOptions(options: Partial<DataSourceOptions>): this {
        Object.assign(this.options, options)

        if (options.logger || options.logging) {
            this.logger = new LoggerFactory().create(
                options.logger || this.options.logger,
                options.logging || this.options.logging,
            )
        }

        if (options.namingStrategy) {
            this.namingStrategy = options.namingStrategy
        }

        if (options.cache) {
            this.queryResultCache = new QueryResultCacheFactory(this).create()
        }

        // todo: we must update the database in the driver as well, if it was set by setOptions method
        //  in the future we need to refactor the code and remove "database" from the driver, and instead
        //  use database (and options) from a single place - data source.
        if (options.database) {
            this.driver.database = DriverUtils.buildDriverOptions(
                this.options,
            ).database
        }

        // todo: need to take a look if we need to update schema and other "poor" properties

        return this
    }

    /**
     * Performs connection to the database.
     * This method should be called once on application bootstrap.
     * This method not necessarily creates database connection (depend on database type),
     * but it also can setup a connection pool with database to use.
     */
    async initialize(): Promise<this> {
        if (this.isInitialized)
            throw new CannotConnectAlreadyConnectedError(this.name)

        // connect to the database via its driver
        await this.driver.connect()

        // connect to the cache-specific database if cache is enabled
        if (this.queryResultCache) await this.queryResultCache.connect()

        // set connected status for the current connection
        ObjectUtils.assign(this, { isInitialized: true })

        try {
            // build all metadatas registered in the current connection
            await this.buildMetadatas()

            await this.driver.afterConnect()

            // if option is set - drop schema once connection is done
            if (this.options.dropSchema) await this.dropDatabase()

            // if option is set - automatically synchronize a schema
            if (this.options.migrationsRun)
                await this.runMigrations({
                    transaction: this.options.migrationsTransactionMode,
                })

            // if option is set - automatically synchronize a schema
            if (this.options.synchronize) await this.synchronize()
        } catch (error) {
            // if for some reason build metadata fail (for example validation error during entity metadata check)
            // connection needs to be closed
            await this.destroy()
            throw error
        }

        return this
    }

    /**
     * Performs connection to the database.
     * This method should be called once on application bootstrap.
     * This method not necessarily creates database connection (depend on database type),
     * but it also can setup a connection pool with database to use.
     *
     * @deprecated use .initialize method instead
     */
    async connect(): Promise<this> {
        return this.initialize()
    }

    /**
     * Closes connection with the database.
     * Once connection is closed, you cannot use repositories or perform any operations except opening connection again.
     */
    async destroy(): Promise<void> {
        if (!this.isInitialized)
            throw new CannotExecuteNotConnectedError(this.name)

        await this.driver.disconnect()

        // disconnect from the cache-specific database if cache was enabled
        if (this.queryResultCache) await this.queryResultCache.disconnect()

        ObjectUtils.assign(this, { isInitialized: false })
    }

    /**
     * Closes connection with the database.
     * Once connection is closed, you cannot use repositories or perform any operations except opening connection again.
     *
     * @deprecated use .destroy method instead
     */
    async close(): Promise<void> {
        return this.destroy()
    }

    /**
     * Creates database schema for all entities registered in this connection.
     * Can be used only after connection to the database is established.
     *
     * @param dropBeforeSync If set to true then it drops the database with all its tables and data
     */
    async synchronize(dropBeforeSync: boolean = false): Promise<void> {
        if (!this.isInitialized)
            throw new CannotExecuteNotConnectedError(this.name)

        if (dropBeforeSync) await this.dropDatabase()

        const schemaBuilder = this.driver.createSchemaBuilder()
        await schemaBuilder.build()
    }

    /**
     * Drops the database and all its data.
     * Be careful with this method on production since this method will erase all your database tables and their data.
     * Can be used only after connection to the database is established.
     */
    // TODO rename
    async dropDatabase(): Promise<void> {
        const queryRunner = this.createQueryRunner()
        try {
            if (
                this.driver.options.type === "mssql" ||
                DriverUtils.isMySQLFamily(this.driver) ||
                this.driver.options.type === "aurora-mysql" ||
                DriverUtils.isSQLiteFamily(this.driver)
            ) {
                const databases: string[] = []
                this.entityMetadatas.forEach((metadata) => {
                    if (
                        metadata.database &&
                        databases.indexOf(metadata.database) === -1
                    )
                        databases.push(metadata.database)
                })
                if (databases.length === 0 && this.driver.database) {
                    databases.push(this.driver.database)
                }

                if (databases.length === 0) {
                    await queryRunner.clearDatabase()
                } else {
                    for (const database of databases) {
                        await queryRunner.clearDatabase(database)
                    }
                }
            } else {
                await queryRunner.clearDatabase()
            }
        } finally {
            await queryRunner.release()
        }
    }

    /**
     * Runs all pending migrations.
     * Can be used only after connection to the database is established.
     */
    async runMigrations(options?: {
        transaction?: "all" | "none" | "each"
        fake?: boolean
    }): Promise<Migration[]> {
        if (!this.isInitialized)
            throw new CannotExecuteNotConnectedError(this.name)

        const migrationExecutor = new MigrationExecutor(this)
        migrationExecutor.transaction =
            (options && options.transaction) || "all"
        migrationExecutor.fake = (options && options.fake) || false

        const successMigrations =
            await migrationExecutor.executePendingMigrations()
        return successMigrations
    }

    /**
     * Reverts last executed migration.
     * Can be used only after connection to the database is established.
     */
    async undoLastMigration(options?: {
        transaction?: "all" | "none" | "each"
        fake?: boolean
    }): Promise<void> {
        if (!this.isInitialized)
            throw new CannotExecuteNotConnectedError(this.name)

        const migrationExecutor = new MigrationExecutor(this)
        migrationExecutor.transaction =
            (options && options.transaction) || "all"
        migrationExecutor.fake = (options && options.fake) || false

        await migrationExecutor.undoLastMigration()
    }

    /**
     * Lists all migrations and whether they have been run.
     * Returns true if there are pending migrations
     */
    async showMigrations(): Promise<boolean> {
        if (!this.isInitialized) {
            throw new CannotExecuteNotConnectedError(this.name)
        }
        const migrationExecutor = new MigrationExecutor(this)
        return await migrationExecutor.showMigrations()
    }

    /**
     * Checks if entity metadata exist for the given entity class, target name or table name.
     */
    hasMetadata(target: EntityTarget<any>): boolean {
        return !!this.findMetadata(target)
    }

    /**
     * Gets entity metadata for the given entity class or schema name.
     */
    getMetadata(target: EntityTarget<any>): EntityMetadata {
        const metadata = this.findMetadata(target)
        if (!metadata) throw new EntityMetadataNotFoundError(target)

        return metadata
    }

    /**
     * Gets repository for the given entity.
     */
    getRepository<Entity extends ObjectLiteral>(
        target: EntityTarget<Entity>,
    ): Repository<Entity> {
        return this.manager.getRepository(target)
    }

    /**
     * Gets tree repository for the given entity class or name.
     * Only tree-type entities can have a TreeRepository, like ones decorated with @Tree decorator.
     */
    getTreeRepository<Entity extends ObjectLiteral>(
        target: EntityTarget<Entity>,
    ): TreeRepository<Entity> {
        return this.manager.getTreeRepository(target)
    }

    /**
     * Gets mongodb-specific repository for the given entity class or name.
     * Works only if connection is mongodb-specific.
     */
    getMongoRepository<Entity extends ObjectLiteral>(
        target: EntityTarget<Entity>,
    ): MongoRepository<Entity> {
        if (!(this.driver.options.type === "mongodb"))
            throw new TypeORMError(
                `You can use getMongoRepository only for MongoDB connections.`,
            )

        return this.manager.getRepository(target) as any
    }

    /**
     * Gets custom entity repository marked with @EntityRepository decorator.
     *
     * @deprecated use Repository.extend function to create a custom repository
     */
    getCustomRepository<T>(customRepository: ObjectType<T>): T {
        return this.manager.getCustomRepository(customRepository)
    }

    /**
     * Wraps given function execution (and all operations made there) into a transaction.
     * All database operations must be executed using provided entity manager.
     */
    async transaction<T>(
        runInTransaction: (entityManager: EntityManager) => Promise<T>,
    ): Promise<T>
    async transaction<T>(
        isolationLevel: IsolationLevel,
        runInTransaction: (entityManager: EntityManager) => Promise<T>,
    ): Promise<T>
    async transaction<T>(
        isolationOrRunInTransaction:
            | IsolationLevel
            | ((entityManager: EntityManager) => Promise<T>),
        runInTransactionParam?: (entityManager: EntityManager) => Promise<T>,
    ): Promise<any> {
        return this.manager.transaction(
            isolationOrRunInTransaction as any,
            runInTransactionParam as any,
        )
    }

    /**
     * Executes raw SQL query and returns raw database results.
     */
    async query<T = any>(
        query: string,
        parameters?: any[],
        queryRunner?: QueryRunner,
    ): Promise<T> {
        if (InstanceChecker.isMongoEntityManager(this.manager))
            throw new TypeORMError(`Queries aren't supported by MongoDB.`)

        if (queryRunner && queryRunner.isReleased)
            throw new QueryRunnerProviderAlreadyReleasedError()

        const usedQueryRunner = queryRunner || this.createQueryRunner()

        try {
            return await usedQueryRunner.query(query, parameters) // await is needed here because we are using finally
        } finally {
            if (!queryRunner) await usedQueryRunner.release()
        }
    }

    /**
     * Creates a new query builder that can be used to build a SQL query.
     */
    createQueryBuilder<Entity extends ObjectLiteral>(
        entityClass: EntityTarget<Entity>,
        alias: string,
        queryRunner?: QueryRunner,
    ): SelectQueryBuilder<Entity>

    /**
     * Creates a new query builder that can be used to build a SQL query.
     */
    createQueryBuilder(queryRunner?: QueryRunner): SelectQueryBuilder<any>

    /**
     * Creates a new query builder that can be used to build a SQL query.
     */
    createQueryBuilder<Entity extends ObjectLiteral>(
        entityOrRunner?: EntityTarget<Entity> | QueryRunner,
        alias?: string,
        queryRunner?: QueryRunner,
    ): SelectQueryBuilder<Entity> {
        if (InstanceChecker.isMongoEntityManager(this.manager))
            throw new TypeORMError(`Query Builder is not supported by MongoDB.`)

        if (alias) {
            alias = DriverUtils.buildAlias(this.driver, undefined, alias)
            const metadata = this.getMetadata(
                entityOrRunner as EntityTarget<Entity>,
            )
            return new SelectQueryBuilder(this, queryRunner)
                .select(alias)
                .from(metadata.target, alias)
        } else {
            return new SelectQueryBuilder(
                this,
                entityOrRunner as QueryRunner | undefined,
            )
        }
    }

    /**
     * Creates a query runner used for perform queries on a single database connection.
     * Using query runners you can control your queries to execute using single database connection and
     * manually control your database transaction.
     *
     * Mode is used in replication mode and indicates whatever you want to connect
     * to master database or any of slave databases.
     * If you perform writes you must use master database,
     * if you perform reads you can use slave databases.
     */
    createQueryRunner(mode: ReplicationMode = "master"): QueryRunner {
        const queryRunner = this.driver.createQueryRunner(mode)
        const manager = this.createEntityManager(queryRunner)
        Object.assign(queryRunner, { manager: manager })
        return queryRunner
    }

    /**
     * Gets entity metadata of the junction table (many-to-many table).
     */
    getManyToManyMetadata(
        entityTarget: EntityTarget<any>,
        relationPropertyPath: string,
    ) {
        const relationMetadata =
            this.getMetadata(entityTarget).findRelationWithPropertyPath(
                relationPropertyPath,
            )
        if (!relationMetadata)
            throw new TypeORMError(
                `Relation "${relationPropertyPath}" was not found in ${entityTarget} entity.`,
            )
        if (!relationMetadata.isManyToMany)
            throw new TypeORMError(
                `Relation "${entityTarget}#${relationPropertyPath}" does not have a many-to-many relationship.` +
                    `You can use this method only on many-to-many relations.`,
            )

        return relationMetadata.junctionEntityMetadata
    }

    /**
     * Creates an Entity Manager for the current connection with the help of the EntityManagerFactory.
     */
    createEntityManager(queryRunner?: QueryRunner): EntityManager {
        return new EntityManagerFactory().create(this, queryRunner)
    }

    // -------------------------------------------------------------------------
    // Protected Methods
    // -------------------------------------------------------------------------

    /**
     * Finds exist entity metadata by the given entity class, target name or table name.
     */
    protected findMetadata(
        target: EntityTarget<any>,
    ): EntityMetadata | undefined {
        const metadataFromMap = this.entityMetadatasMap.get(target)
        if (metadataFromMap) return metadataFromMap

        for (let [_, metadata] of this.entityMetadatasMap) {
            if (
                InstanceChecker.isEntitySchema(target) &&
                metadata.name === target.options.name
            ) {
                return metadata
            }
            if (typeof target === "string") {
                if (target.indexOf(".") !== -1) {
                    if (metadata.tablePath === target) {
                        return metadata
                    }
                } else {
                    if (
                        metadata.name === target ||
                        metadata.tableName === target
                    ) {
                        return metadata
                    }
                }
            }
            if (
                ObjectUtils.isObjectWithName(target) &&
                typeof target.name === "string"
            ) {
                if (target.name.indexOf(".") !== -1) {
                    if (metadata.tablePath === target.name) {
                        return metadata
                    }
                } else {
                    if (
                        metadata.name === target.name ||
                        metadata.tableName === target.name
                    ) {
                        return metadata
                    }
                }
            }
        }

        return undefined
    }

    private async getEntityMetadatas(
        connectionMetadataBuilder: ConnectionMetadataBuilder,
    ) {
        if (
            this.options.metadataNamespace &&
            DataSource.MetadataCache.has(this.options.metadataNamespace)
        ) {
            return DataSource.MetadataCache.get(this.options.metadataNamespace)!
        }

        const flattenedEntities = ObjectUtils.mixedListToArray(
            this.options.entities || [],
        )
        const entityMetadatas =
            await connectionMetadataBuilder.buildEntityMetadatas(
                flattenedEntities,
            )
        if (
            this.options.metadataNamespace &&
            !DataSource.MetadataCache.has(this.options.metadataNamespace)
        ) {
            DataSource.MetadataCache.set(
                this.options.metadataNamespace,
                entityMetadatas,
            )
        }

        return entityMetadatas
    }

    /**
     * Builds metadatas for all registered classes inside this connection.
     */
    protected async buildMetadatas(): Promise<void> {
        const connectionMetadataBuilder = new ConnectionMetadataBuilder(this)
        const entityMetadataValidator = new EntityMetadataValidator()

        // create subscribers instances if they are not disallowed from high-level (for example they can disallowed from migrations run process)
        const flattenedSubscribers = ObjectUtils.mixedListToArray(
            this.options.subscribers || [],
        )
        const subscribers = await connectionMetadataBuilder.buildSubscribers(
            flattenedSubscribers,
        )
        ObjectUtils.assign(this, { subscribers: subscribers })

        // build entity metadatas
        const entityMetadatas = await this.getEntityMetadatas(
            connectionMetadataBuilder,
        )
        ObjectUtils.assign(this, {
            entityMetadatas: entityMetadatas,
            entityMetadatasMap: new Map(
                entityMetadatas.map((metadata) => [metadata.target, metadata]),
            ),
        })

        // create migration instances
        const flattenedMigrations = ObjectUtils.mixedListToArray(
            this.options.migrations || [],
        )
        const migrations = await connectionMetadataBuilder.buildMigrations(
            flattenedMigrations,
        )
        ObjectUtils.assign(this, { migrations: migrations })

        // validate all created entity metadatas to make sure user created entities are valid and correct
        entityMetadataValidator.validateMany(
            this.entityMetadatas.filter(
                (metadata) => metadata.tableType !== "view",
            ),
            this.driver,
        )

        // set current data source to the entities
        for (let entityMetadata of entityMetadatas) {
            if (
                InstanceChecker.isBaseEntityConstructor(entityMetadata.target)
            ) {
                entityMetadata.target.useDataSource(this)
            }
        }
    }
}