import { AbstractSqliteDriver } from "../sqlite-abstract/AbstractSqliteDriver"
import { SqljsConnectionOptions } from "./SqljsConnectionOptions"
import { SqljsQueryRunner } from "./SqljsQueryRunner"
import { QueryRunner } from "../../query-runner/QueryRunner"
import { DataSource } from "../../data-source/DataSource"
import { DriverPackageNotInstalledError } from "../../error/DriverPackageNotInstalledError"
import { DriverOptionNotSetError } from "../../error/DriverOptionNotSetError"
import { PlatformTools } from "../../platform/PlatformTools"
import { EntityMetadata } from "../../metadata/EntityMetadata"
import { OrmUtils } from "../../util/OrmUtils"
import { ObjectLiteral } from "../../common/ObjectLiteral"
import { ReplicationMode } from "../types/ReplicationMode"
import { TypeORMError } from "../../error"

// This is needed to satisfy the typescript compiler.
interface Window {
    SQL: any
    localforage: any
}
declare let window: Window

export class SqljsDriver extends AbstractSqliteDriver {
    // The driver specific options.
    options: SqljsConnectionOptions

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

    constructor(connection: DataSource) {
        super(connection)

        // If autoSave is enabled by user, location or autoSaveCallback have to be set
        // because either autoSave saves to location or calls autoSaveCallback.
        if (
            this.options.autoSave &&
            !this.options.location &&
            !this.options.autoSaveCallback
        ) {
            throw new DriverOptionNotSetError(`location or autoSaveCallback`)
        }

        // load sql.js package
        this.loadDependencies()
    }

    // -------------------------------------------------------------------------
    // Public Methods
    // -------------------------------------------------------------------------

    /**
     * Performs connection to the database.
     */
    async connect(): Promise<void> {
        this.databaseConnection = await this.createDatabaseConnection()
    }

    /**
     * Closes connection with database.
     */
    async disconnect(): Promise<void> {
        this.queryRunner = undefined
        this.databaseConnection.close()
    }

    /**
     * Creates a query runner used to execute database queries.
     */
    createQueryRunner(mode: ReplicationMode): QueryRunner {
        if (!this.queryRunner) this.queryRunner = new SqljsQueryRunner(this)

        return this.queryRunner
    }

    /**
     * Loads a database from a given file (Node.js), local storage key (browser) or array.
     * This will delete the current database!
     */
    async load(
        fileNameOrLocalStorageOrData: string | Uint8Array,
        checkIfFileOrLocalStorageExists: boolean = true,
    ): Promise<any> {
        if (typeof fileNameOrLocalStorageOrData === "string") {
            // content has to be loaded
            if (PlatformTools.type === "node") {
                // Node.js
                // fileNameOrLocalStorageOrData should be a path to the file
                if (PlatformTools.fileExist(fileNameOrLocalStorageOrData)) {
                    const database = PlatformTools.readFileSync(
                        fileNameOrLocalStorageOrData,
                    )
                    return this.createDatabaseConnectionWithImport(database)
                } else if (checkIfFileOrLocalStorageExists) {
                    throw new TypeORMError(
                        `File ${fileNameOrLocalStorageOrData} does not exist`,
                    )
                } else {
                    // File doesn't exist and checkIfFileOrLocalStorageExists is set to false.
                    // Therefore open a database without importing an existing file.
                    // File will be written on first write operation.
                    return this.createDatabaseConnectionWithImport()
                }
            } else {
                // browser
                // fileNameOrLocalStorageOrData should be a local storage / indexedDB key
                let localStorageContent = null
                if (this.options.useLocalForage) {
                    if (window.localforage) {
                        localStorageContent = await window.localforage.getItem(
                            fileNameOrLocalStorageOrData,
                        )
                    } else {
                        throw new TypeORMError(
                            `localforage is not defined - please import localforage.js into your site`,
                        )
                    }
                } else {
                    localStorageContent =
                        PlatformTools.getGlobalVariable().localStorage.getItem(
                            fileNameOrLocalStorageOrData,
                        )
                }

                if (localStorageContent != null) {
                    // localStorage value exists.
                    return this.createDatabaseConnectionWithImport(
                        JSON.parse(localStorageContent),
                    )
                } else if (checkIfFileOrLocalStorageExists) {
                    throw new TypeORMError(
                        `File ${fileNameOrLocalStorageOrData} does not exist`,
                    )
                } else {
                    // localStorage value doesn't exist and checkIfFileOrLocalStorageExists is set to false.
                    // Therefore open a database without importing anything.
                    // localStorage value will be written on first write operation.
                    return this.createDatabaseConnectionWithImport()
                }
            }
        } else {
            return this.createDatabaseConnectionWithImport(
                fileNameOrLocalStorageOrData,
            )
        }
    }

    /**
     * Saved the current database to the given file (Node.js), local storage key (browser) or
     * indexedDB key (browser with enabled useLocalForage option).
     * If no location path is given, the location path in the options (if specified) will be used.
     */
    async save(location?: string) {
        if (!location && !this.options.location) {
            throw new TypeORMError(
                `No location is set, specify a location parameter or add the location option to your configuration`,
            )
        }

        let path = ""
        if (location) {
            path = location
        } else if (this.options.location) {
            path = this.options.location
        }

        if (PlatformTools.type === "node") {
            try {
                const content = Buffer.from(this.databaseConnection.export())
                await PlatformTools.writeFile(path, content)
            } catch (e) {
                throw new TypeORMError(`Could not save database, error: ${e}`)
            }
        } else {
            const database: Uint8Array = this.databaseConnection.export()
            // convert Uint8Array to number array to improve local-storage storage
            const databaseArray = [].slice.call(database)
            if (this.options.useLocalForage) {
                if (window.localforage) {
                    await window.localforage.setItem(
                        path,
                        JSON.stringify(databaseArray),
                    )
                } else {
                    throw new TypeORMError(
                        `localforage is not defined - please import localforage.js into your site`,
                    )
                }
            } else {
                PlatformTools.getGlobalVariable().localStorage.setItem(
                    path,
                    JSON.stringify(databaseArray),
                )
            }
        }
    }

    /**
     * This gets called by the QueryRunner when a change to the database is made.
     * If a custom autoSaveCallback is specified, it get's called with the database as Uint8Array,
     * otherwise the save method is called which saves it to file (Node.js), local storage (browser)
     * or indexedDB (browser with enabled useLocalForage option).
     * Don't auto-save when in transaction as the call to export will end the current transaction
     */
    async autoSave() {
        if (this.options.autoSave && !this.queryRunner?.isTransactionActive) {
            if (this.options.autoSaveCallback) {
                await this.options.autoSaveCallback(this.export())
            } else {
                await this.save()
            }
        }
    }

    /**
     * Returns the current database as Uint8Array.
     */
    export(): Uint8Array {
        return this.databaseConnection.export()
    }

    /**
     * Creates generated map of values generated or returned by database after INSERT query.
     */
    createGeneratedMap(metadata: EntityMetadata, insertResult: any) {
        const generatedMap = metadata.generatedColumns.reduce(
            (map, generatedColumn) => {
                // seems to be the only way to get the inserted id, see https://github.com/kripken/sql.js/issues/77
                if (
                    generatedColumn.isPrimary &&
                    generatedColumn.generationStrategy === "increment"
                ) {
                    const query = "SELECT last_insert_rowid()"
                    try {
                        let result = this.databaseConnection.exec(query)
                        this.connection.logger.logQuery(query)
                        return OrmUtils.mergeDeep(
                            map,
                            generatedColumn.createValueMap(
                                result[0].values[0][0],
                            ),
                        )
                    } catch (e) {
                        this.connection.logger.logQueryError(e, query, [])
                    }
                }

                return map
            },
            {} as ObjectLiteral,
        )

        return Object.keys(generatedMap).length > 0 ? generatedMap : undefined
    }

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

    /**
     * Creates connection with the database.
     * If the location option is set, the database is loaded first.
     */
    protected createDatabaseConnection(): Promise<any> {
        if (this.options.location) {
            return this.load(this.options.location, false)
        }

        return this.createDatabaseConnectionWithImport(this.options.database)
    }

    /**
     * Creates connection with an optional database.
     * If database is specified it is loaded, otherwise a new empty database is created.
     */
    protected async createDatabaseConnectionWithImport(
        database?: Uint8Array,
    ): Promise<any> {
        // sql.js < 1.0 exposes an object with a `Database` method.
        const isLegacyVersion = typeof this.sqlite.Database === "function"
        const sqlite = isLegacyVersion
            ? this.sqlite
            : await this.sqlite(this.options.sqlJsConfig)
        if (database && database.length > 0) {
            this.databaseConnection = new sqlite.Database(database)
        } else {
            this.databaseConnection = new sqlite.Database()
        }

        this.databaseConnection.exec(`PRAGMA foreign_keys = ON`)

        return this.databaseConnection
    }

    /**
     * If driver dependency is not given explicitly, then try to load it via "require".
     */
    protected loadDependencies(): void {
        if (PlatformTools.type === "browser") {
            const sqlite = this.options.driver || window.SQL
            this.sqlite = sqlite
        } else {
            try {
                const sqlite =
                    this.options.driver || PlatformTools.load("sql.js")
                this.sqlite = sqlite
            } catch (e) {
                throw new DriverPackageNotInstalledError("sql.js", "sql.js")
            }
        }
    }
}