import {
  Integration,
  DatasourceFieldTypes,
  QueryTypes,
  SqlQuery,
  QueryJson,
} from "../definitions/datasource"
import {
  finaliseExternalTables,
  getSqlQuery,
  buildExternalTableId,
  convertSqlType,
} from "./utils"
import oracledb, {
  ExecuteOptions,
  Result,
  Connection,
  ConnectionAttributes,
  BindParameters,
} from "oracledb"
import Sql from "./base/sql"
import { Table } from "../definitions/common"
import { DatasourcePlus } from "./base/datasourcePlus"
import { FieldTypes } from "../constants"

module OracleModule {
  oracledb.outFormat = oracledb.OUT_FORMAT_OBJECT

  interface OracleConfig {
    host: string
    port: number
    database: string
    user: string
    password: string
  }

  const SCHEMA: Integration = {
    docs: "https://github.com/oracle/node-oracledb",
    plus: true,
    friendlyName: "Oracle",
    description:
      "Oracle Database is an object-relational database management system developed by Oracle Corporation",
    datasource: {
      host: {
        type: DatasourceFieldTypes.STRING,
        default: "localhost",
        required: true,
      },
      port: {
        type: DatasourceFieldTypes.NUMBER,
        required: true,
        default: 1521,
      },
      database: {
        type: DatasourceFieldTypes.STRING,
        required: true,
      },
      user: {
        type: DatasourceFieldTypes.STRING,
        required: true,
      },
      password: {
        type: DatasourceFieldTypes.PASSWORD,
        required: true,
      },
    },
    query: {
      create: {
        type: QueryTypes.SQL,
      },
      read: {
        type: QueryTypes.SQL,
      },
      update: {
        type: QueryTypes.SQL,
      },
      delete: {
        type: QueryTypes.SQL,
      },
    },
  }

  const UNSUPPORTED_TYPES = ["BLOB", "CLOB", "NCLOB"]

  /**
   * Raw query response
   */
  interface ColumnsResponse {
    TABLE_NAME: string
    COLUMN_NAME: string
    DATA_TYPE: string
    DATA_DEFAULT: string | null
    COLUMN_ID: number
    CONSTRAINT_NAME: string | null
    CONSTRAINT_TYPE: string | null
    R_CONSTRAINT_NAME: string | null
    SEARCH_CONDITION: string | null
  }

  /**
   * An oracle constraint
   */
  interface OracleConstraint {
    name: string
    type: string
    relatedConstraintName: string | null
    searchCondition: string | null
  }

  /**
   * An oracle column and it's related constraints
   */
  interface OracleColumn {
    name: string
    type: string
    default: string | null
    id: number
    constraints: { [key: string]: OracleConstraint }
  }

  /**
   * An oracle table and it's related columns
   */
  interface OracleTable {
    name: string
    columns: { [key: string]: OracleColumn }
  }

  const OracleContraintTypes = {
    PRIMARY: "P",
    NOT_NULL_OR_CHECK: "C",
    FOREIGN_KEY: "R",
    UNIQUE: "U",
  }

  class OracleIntegration extends Sql implements DatasourcePlus {
    private readonly config: OracleConfig

    public tables: Record<string, Table> = {}
    public schemaErrors: Record<string, string> = {}

    private readonly COLUMNS_SQL = `
      SELECT
        tabs.table_name,
        cols.column_name,
        cols.data_type,
        cols.data_default,
        cols.column_id,
        cons.constraint_name,
        cons.constraint_type,
        cons.r_constraint_name,
        cons.search_condition
      FROM
        user_tables tabs
      JOIN 
        user_tab_columns cols
        ON tabs.table_name = cols.table_name 
      LEFT JOIN 
        user_cons_columns col_cons
        ON cols.column_name = col_cons.column_name
        AND cols.table_name = col_cons.table_name
      LEFT JOIN 
        user_constraints cons
        ON col_cons.constraint_name = cons.constraint_name
        AND cons.table_name = cols.table_name
      WHERE
        (cons.status = 'ENABLED'
          OR cons.status IS NULL)
    `
    constructor(config: OracleConfig) {
      super("oracledb")
      this.config = config
    }

    /**
     * Map the flat tabular columns and constraints data into a nested object
     */
    private mapColumns(result: Result<ColumnsResponse>): {
      [key: string]: OracleTable
    } {
      const oracleTables: { [key: string]: OracleTable } = {}

      if (result.rows) {
        result.rows.forEach(row => {
          const tableName = row.TABLE_NAME
          const columnName = row.COLUMN_NAME
          const dataType = row.DATA_TYPE
          const dataDefault = row.DATA_DEFAULT
          const columnId = row.COLUMN_ID
          const constraintName = row.CONSTRAINT_NAME
          const constraintType = row.CONSTRAINT_TYPE
          const relatedConstraintName = row.R_CONSTRAINT_NAME
          const searchCondition = row.SEARCH_CONDITION

          let table = oracleTables[tableName]
          if (!table) {
            table = {
              name: tableName,
              columns: {},
            }
            oracleTables[tableName] = table
          }

          let column = table.columns[columnName]
          if (!column) {
            column = {
              name: columnName,
              type: dataType,
              default: dataDefault,
              id: columnId,
              constraints: {},
            }
            table.columns[columnName] = column
          }

          if (constraintName && constraintType) {
            let constraint = column.constraints[constraintName]
            if (!constraint) {
              constraint = {
                name: constraintName,
                type: constraintType,
                relatedConstraintName: relatedConstraintName,
                searchCondition: searchCondition,
              }
            }
            column.constraints[constraintName] = constraint
          }
        })
      }

      return oracleTables
    }

    private isSupportedColumn(column: OracleColumn) {
      if (UNSUPPORTED_TYPES.includes(column.type)) {
        return false
      }

      return true
    }

    private isAutoColumn(column: OracleColumn) {
      if (column.default && column.default.toLowerCase().includes("nextval")) {
        return true
      }

      return false
    }

    /**
     * No native boolean in oracle. Best we can do is to check if a manual 1 or 0 number constraint has been set up
     * This matches the default behaviour for generating DDL used in knex.
     */
    private isBooleanType(column: OracleColumn): boolean {
      if (
        column.type.toLowerCase() === "number" &&
        Object.values(column.constraints).filter(c => {
          if (
            c.type === OracleContraintTypes.NOT_NULL_OR_CHECK &&
            c.searchCondition
          ) {
            const condition = c.searchCondition
              .replace(/\s/g, "") // remove spaces
              .replace(/[']+/g, "") // remove quotes
            if (
              condition.includes("in(0,1)") ||
              condition.includes("in(1,0)")
            ) {
              return true
            }
          }
          return false
        }).length > 0
      ) {
        return true
      }

      return false
    }

    private internalConvertType(column: OracleColumn): string {
      if (this.isBooleanType(column)) {
        return FieldTypes.BOOLEAN
      }

      return convertSqlType(column.type)
    }

    /**
     * Fetches the tables from the oracle table and assigns them to the datasource.
     * @param {*} datasourceId - datasourceId to fetch
     * @param entities - the tables that are to be built
     */
    async buildSchema(datasourceId: string, entities: Record<string, Table>) {
      const columnsResponse = await this.internalQuery<ColumnsResponse>({
        sql: this.COLUMNS_SQL,
      })
      const oracleTables = this.mapColumns(columnsResponse)

      const tables: { [key: string]: Table } = {}

      // iterate each table
      Object.values(oracleTables).forEach(oracleTable => {
        let table = tables[oracleTable.name]
        if (!table) {
          table = {
            _id: buildExternalTableId(datasourceId, oracleTable.name),
            primary: [],
            name: oracleTable.name,
            schema: {},
          }
          tables[oracleTable.name] = table
        }

        // iterate each column on the table
        Object.values(oracleTable.columns)
          // remove columns that we can't read / save
          .filter(oracleColumn => this.isSupportedColumn(oracleColumn))
          // match the order of the columns in the db
          .sort((c1, c2) => c1.id - c2.id)
          .forEach(oracleColumn => {
            const columnName = oracleColumn.name
            let fieldSchema = table.schema[columnName]
            if (!fieldSchema) {
              fieldSchema = {
                autocolumn: this.isAutoColumn(oracleColumn),
                name: columnName,
                type: this.internalConvertType(oracleColumn),
              }
              table.schema[columnName] = fieldSchema
            }

            // iterate each constraint on the column
            Object.values(oracleColumn.constraints).forEach(
              oracleConstraint => {
                if (oracleConstraint.type === OracleContraintTypes.PRIMARY) {
                  table.primary!.push(columnName)
                }
              }
            )
          })
      })

      const final = finaliseExternalTables(tables, entities)
      this.tables = final.tables
      this.schemaErrors = final.errors
    }

    private async internalQuery<T>(query: SqlQuery): Promise<Result<T>> {
      let connection
      try {
        connection = await this.getConnection()

        const options: ExecuteOptions = { autoCommit: true }
        const bindings: BindParameters = query.bindings || []
        const result: Result<T> = await connection.execute<T>(
          query.sql,
          bindings,
          options
        )

        return result
      } finally {
        if (connection) {
          try {
            await connection.close()
          } catch (err) {
            console.error(err)
          }
        }
      }
    }

    private getConnection = async (): Promise<Connection> => {
      //connectString : "(DESCRIPTION =(ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))(CONNECT_DATA =(SID= ORCL)))"
      const connectString = `${this.config.host}:${this.config.port || 1521}/${
        this.config.database
      }`
      const attributes: ConnectionAttributes = {
        user: this.config.user,
        password: this.config.user,
        connectString,
      }
      return oracledb.getConnection(attributes)
    }

    async create(query: SqlQuery | string): Promise<any[]> {
      const response = await this.internalQuery<any>(getSqlQuery(query))
      return response.rows && response.rows.length
        ? response.rows
        : [{ created: true }]
    }

    async read(query: SqlQuery | string): Promise<any[]> {
      const response = await this.internalQuery<any>(getSqlQuery(query))
      return response.rows ? response.rows : []
    }

    async update(query: SqlQuery | string): Promise<any[]>  {
      const response = await this.internalQuery(getSqlQuery(query))
      return response.rows && response.rows.length
        ? response.rows
        : [{ updated: true }]
    }

    async delete(query: SqlQuery | string): Promise<any[]>  {
      const response = await this.internalQuery(getSqlQuery(query))
      return response.rows && response.rows.length
        ? response.rows
        : [{ deleted: true }]
    }

    async query(json: QueryJson) {
      const operation = this._operation(json).toLowerCase()
      const input = this._query(json, { disableReturning: true })
      if (Array.isArray(input)) {
        const responses = []
        for (let query of input) {
          responses.push(await this.internalQuery(query))
        }
        return responses
      } else {
        const response = await this.internalQuery(input)
        return response.rows && response.rows.length
          ? response.rows
          : [{ [operation]: true }]
      }
    }
  }

  module.exports = {
    schema: SCHEMA,
    integration: OracleIntegration,
  }
}