'use strict'

const debug = require('debug')('mssql:base')
const { EventEmitter } = require('events')
const { IDS, objectHasProperty } = require('../utils')
const globalConnection = require('../global-connection')
const { RequestError, ConnectionError } = require('../error')
const { TYPES } = require('../datatypes')
const shared = require('../shared')

/**
 * Class Request.
 *
 * @property {Transaction} transaction Reference to transaction when request was created in transaction.
 * @property {*} parameters Collection of input and output parameters.
 * @property {Boolean} canceled `true` if request was canceled.
 *
 * @fires Request#recordset
 * @fires Request#row
 * @fires Request#done
 * @fires Request#error
 */

class Request extends EventEmitter {
  /**
   * Create new Request.
   *
   * @param {Connection|ConnectionPool|Transaction|PreparedStatement} parent If ommited, global connection is used instead.
   */

  constructor (parent) {
    super()

    IDS.add(this, 'Request')
    debug('request(%d): created', IDS.get(this))

    this.canceled = false
    this._paused = false
    this.parent = parent || globalConnection.pool
    this.parameters = {}
  }

  get paused () {
    return this._paused
  }

  /**
   * Generate sql string and set imput parameters from tagged template string.
   *
   * @param {Template literal} template
   * @return {String}
   */
  template () {
    const values = Array.prototype.slice.call(arguments)
    const strings = values.shift()
    return this._template(strings, values)
  }

  /**
   * Fetch request from tagged template string.
   *
   * @private
   * @param {Array} strings
   * @param {Array} values
   * @param {String} [method] If provided, method is automatically called with serialized command on this object.
   * @return {Request}
   */

  _template (strings, values, method) {
    const command = [strings[0]]

    for (let index = 0; index < values.length; index++) {
      const value = values[index]
      // if value is an array, prepare each items as it's own comma separated parameter
      if (Array.isArray(value)) {
        for (let parameterIndex = 0; parameterIndex < value.length; parameterIndex++) {
          this.input(`param${index + 1}_${parameterIndex}`, value[parameterIndex])
          command.push(`@param${index + 1}_${parameterIndex}`)
          if (parameterIndex < value.length - 1) {
            command.push(', ')
          }
        }
        command.push(strings[index + 1])
      } else {
        this.input(`param${index + 1}`, value)
        command.push(`@param${index + 1}`, strings[index + 1])
      }
    }

    if (method) {
      return this[method](command.join(''))
    } else {
      return command.join('')
    }
  }

  /**
   * Add an input parameter to the request.
   *
   * @param {String} name Name of the input parameter without @ char.
   * @param {*} [type] SQL data type of input parameter. If you omit type, module automaticaly decide which SQL data type should be used based on JS data type.
   * @param {*} value Input parameter value. `undefined` and `NaN` values are automatically converted to `null` values.
   * @return {Request}
   */

  input (name, type, value) {
    if ((/(--| |\/\*|\*\/|')/).test(name)) {
      throw new RequestError(`SQL injection warning for param '${name}'`, 'EINJECT')
    }

    if (arguments.length < 2) {
      throw new RequestError('Invalid number of arguments. At least 2 arguments expected.', 'EARGS')
    } else if (arguments.length === 2) {
      value = type
      type = shared.getTypeByValue(value)
    }

    // support for custom data types
    if (value && typeof value.valueOf === 'function' && !(value instanceof Date)) value = value.valueOf()

    if (value === undefined) value = null // undefined to null
    if (typeof value === 'number' && isNaN(value)) value = null // NaN to null
    if (type instanceof Function) type = type()

    if (objectHasProperty(this.parameters, name)) {
      throw new RequestError(`The parameter name ${name} has already been declared. Parameter names must be unique`, 'EDUPEPARAM')
    }

    this.parameters[name] = {
      name,
      type: type.type,
      io: 1,
      value,
      length: type.length,
      scale: type.scale,
      precision: type.precision,
      tvpType: type.tvpType
    }

    return this
  }

  /**
   * Replace an input parameter on the request.
   *
   * @param {String} name Name of the input parameter without @ char.
   * @param {*} [type] SQL data type of input parameter. If you omit type, module automaticaly decide which SQL data type should be used based on JS data type.
   * @param {*} value Input parameter value. `undefined` and `NaN` values are automatically converted to `null` values.
   * @return {Request}
   */

  replaceInput (name, type, value) {
    delete this.parameters[name]

    return this.input(name, type, value)
  }

  /**
   * Add an output parameter to the request.
   *
   * @param {String} name Name of the output parameter without @ char.
   * @param {*} type SQL data type of output parameter.
   * @param {*} [value] Output parameter value initial value. `undefined` and `NaN` values are automatically converted to `null` values. Optional.
   * @return {Request}
   */

  output (name, type, value) {
    if (!type) { type = TYPES.NVarChar }

    if ((/(--| |\/\*|\*\/|')/).test(name)) {
      throw new RequestError(`SQL injection warning for param '${name}'`, 'EINJECT')
    }

    if ((type === TYPES.Text) || (type === TYPES.NText) || (type === TYPES.Image)) {
      throw new RequestError('Deprecated types (Text, NText, Image) are not supported as OUTPUT parameters.', 'EDEPRECATED')
    }

    // support for custom data types
    if (value && typeof value.valueOf === 'function' && !(value instanceof Date)) value = value.valueOf()

    if (value === undefined) value = null // undefined to null
    if (typeof value === 'number' && isNaN(value)) value = null // NaN to null
    if (type instanceof Function) type = type()

    if (objectHasProperty(this.parameters, name)) {
      throw new RequestError(`The parameter name ${name} has already been declared. Parameter names must be unique`, 'EDUPEPARAM')
    }

    this.parameters[name] = {
      name,
      type: type.type,
      io: 2,
      value,
      length: type.length,
      scale: type.scale,
      precision: type.precision
    }

    return this
  }

  /**
   * Replace an output parameter on the request.
   *
   * @param {String} name Name of the output parameter without @ char.
   * @param {*} type SQL data type of output parameter.
   * @param {*} [value] Output parameter value initial value. `undefined` and `NaN` values are automatically converted to `null` values. Optional.
   * @return {Request}
   */

  replaceOutput (name, type, value) {
    delete this.parameters[name]

    return this.output(name, type, value)
  }

  /**
   * Execute the SQL batch.
   *
   * @param {String} batch T-SQL batch to be executed.
   * @param {Request~requestCallback} [callback] A callback which is called after execution has completed, or an error has occurred. If omited, method returns Promise.
   * @return {Request|Promise}
   */

  batch (batch, callback) {
    if (this.stream == null && this.connection) this.stream = this.connection.config.stream
    if (this.arrayRowMode == null && this.connection) this.arrayRowMode = this.connection.config.arrayRowMode
    this.rowsAffected = 0

    if (typeof callback === 'function') {
      this._batch(batch, (err, recordsets, output, rowsAffected) => {
        if (this.stream) {
          if (err) this.emit('error', err)
          err = null

          this.emit('done', {
            output,
            rowsAffected
          })
        }

        if (err) return callback(err)
        callback(null, {
          recordsets,
          recordset: recordsets && recordsets[0],
          output,
          rowsAffected
        })
      })
      return this
    }

    // Check is method was called as tagged template
    if (typeof batch === 'object') {
      const values = Array.prototype.slice.call(arguments)
      const strings = values.shift()
      batch = this._template(strings, values)
    }

    return new shared.Promise((resolve, reject) => {
      this._batch(batch, (err, recordsets, output, rowsAffected) => {
        if (this.stream) {
          if (err) this.emit('error', err)
          err = null

          this.emit('done', {
            output,
            rowsAffected
          })
        }

        if (err) return reject(err)
        resolve({
          recordsets,
          recordset: recordsets && recordsets[0],
          output,
          rowsAffected
        })
      })
    })
  }

  /**
   * @private
   * @param {String} batch
   * @param {Request~requestCallback} callback
   */

  _batch (batch, callback) {
    if (!this.connection) {
      return setImmediate(callback, new RequestError('No connection is specified for that request.', 'ENOCONN'))
    }

    if (!this.connection.connected) {
      return setImmediate(callback, new ConnectionError('Connection is closed.', 'ECONNCLOSED'))
    }

    this.canceled = false
    setImmediate(callback)
  }

  /**
   * Bulk load.
   *
   * @param {Table} table SQL table.
   * @param {object} [options] Options to be passed to the underlying driver (tedious only).
   * @param {Request~bulkCallback} [callback] A callback which is called after bulk load has completed, or an error has occurred. If omited, method returns Promise.
   * @return {Request|Promise}
   */

  bulk (table, options, callback) {
    if (typeof options === 'function') {
      callback = options
      options = {}
    } else if (typeof options === 'undefined') {
      options = {}
    }

    if (this.stream == null && this.connection) this.stream = this.connection.config.stream
    if (this.arrayRowMode == null && this.connection) this.arrayRowMode = this.connection.config.arrayRowMode

    if (this.stream || typeof callback === 'function') {
      this._bulk(table, options, (err, rowsAffected) => {
        if (this.stream) {
          if (err) this.emit('error', err)
          return this.emit('done', {
            rowsAffected
          })
        }

        if (err) return callback(err)
        callback(null, {
          rowsAffected
        })
      })
      return this
    }

    return new shared.Promise((resolve, reject) => {
      this._bulk(table, options, (err, rowsAffected) => {
        if (err) return reject(err)
        resolve({
          rowsAffected
        })
      })
    })
  }

  /**
   * @private
   * @param {Table} table
   * @param {object} options
   * @param {Request~bulkCallback} callback
   */

  _bulk (table, options, callback) {
    if (!this.parent) {
      return setImmediate(callback, new RequestError('No connection is specified for that request.', 'ENOCONN'))
    }

    if (!this.parent.connected) {
      return setImmediate(callback, new ConnectionError('Connection is closed.', 'ECONNCLOSED'))
    }

    this.canceled = false
    setImmediate(callback)
  }

  /**
   * Sets request to `stream` mode and pulls all rows from all recordsets to a given stream.
   *
   * @param {Stream} stream Stream to pipe data into.
   * @return {Stream}
   */

  pipe (stream) {
    this.stream = true
    this.on('row', stream.write.bind(stream))
    this.on('error', stream.emit.bind(stream, 'error'))
    this.on('done', () => {
      setImmediate(() => stream.end())
    })
    stream.emit('pipe', this)
    return stream
  }

  /**
   * Execute the SQL command.
   *
   * @param {String} command T-SQL command to be executed.
   * @param {Request~requestCallback} [callback] A callback which is called after execution has completed, or an error has occurred. If omited, method returns Promise.
   * @return {Request|Promise}
   */

  query (command, callback) {
    if (this.stream == null && this.connection) this.stream = this.connection.config.stream
    if (this.arrayRowMode == null && this.connection) this.arrayRowMode = this.connection.config.arrayRowMode
    this.rowsAffected = 0

    if (typeof callback === 'function') {
      this._query(command, (err, recordsets, output, rowsAffected, columns) => {
        if (this.stream) {
          if (err) this.emit('error', err)
          err = null

          this.emit('done', {
            output,
            rowsAffected
          })
        }

        if (err) return callback(err)
        const result = {
          recordsets,
          recordset: recordsets && recordsets[0],
          output,
          rowsAffected
        }
        if (this.arrayRowMode) result.columns = columns
        callback(null, result)
      })
      return this
    }

    // Check is method was called as tagged template
    if (typeof command === 'object') {
      const values = Array.prototype.slice.call(arguments)
      const strings = values.shift()
      command = this._template(strings, values)
    }

    return new shared.Promise((resolve, reject) => {
      this._query(command, (err, recordsets, output, rowsAffected, columns) => {
        if (this.stream) {
          if (err) this.emit('error', err)
          err = null

          this.emit('done', {
            output,
            rowsAffected
          })
        }

        if (err) return reject(err)
        const result = {
          recordsets,
          recordset: recordsets && recordsets[0],
          output,
          rowsAffected
        }
        if (this.arrayRowMode) result.columns = columns
        resolve(result)
      })
    })
  }

  /**
   * @private
   * @param {String} command
   * @param {Request~bulkCallback} callback
   */

  _query (command, callback) {
    if (!this.parent) {
      return setImmediate(callback, new RequestError('No connection is specified for that request.', 'ENOCONN'))
    }

    if (!this.parent.connected) {
      return setImmediate(callback, new ConnectionError('Connection is closed.', 'ECONNCLOSED'))
    }

    this.canceled = false
    setImmediate(callback)
  }

  /**
   * Call a stored procedure.
   *
   * @param {String} procedure Name of the stored procedure to be executed.
   * @param {Request~requestCallback} [callback] A callback which is called after execution has completed, or an error has occurred. If omited, method returns Promise.
   * @return {Request|Promise}
   */

  execute (command, callback) {
    if (this.stream == null && this.connection) this.stream = this.connection.config.stream
    if (this.arrayRowMode == null && this.connection) this.arrayRowMode = this.connection.config.arrayRowMode
    this.rowsAffected = 0

    if (typeof callback === 'function') {
      this._execute(command, (err, recordsets, output, returnValue, rowsAffected, columns) => {
        if (this.stream) {
          if (err) this.emit('error', err)
          err = null

          this.emit('done', {
            output,
            rowsAffected,
            returnValue
          })
        }

        if (err) return callback(err)
        const result = {
          recordsets,
          recordset: recordsets && recordsets[0],
          output,
          rowsAffected,
          returnValue
        }
        if (this.arrayRowMode) result.columns = columns
        callback(null, result)
      })
      return this
    }

    return new shared.Promise((resolve, reject) => {
      this._execute(command, (err, recordsets, output, returnValue, rowsAffected, columns) => {
        if (this.stream) {
          if (err) this.emit('error', err)
          err = null

          this.emit('done', {
            output,
            rowsAffected,
            returnValue
          })
        }

        if (err) return reject(err)
        const result = {
          recordsets,
          recordset: recordsets && recordsets[0],
          output,
          rowsAffected,
          returnValue
        }
        if (this.arrayRowMode) result.columns = columns
        resolve(result)
      })
    })
  }

  /**
   * @private
   * @param {String} procedure
   * @param {Request~bulkCallback} callback
   */

  _execute (procedure, callback) {
    if (!this.parent) {
      return setImmediate(callback, new RequestError('No connection is specified for that request.', 'ENOCONN'))
    }

    if (!this.parent.connected) {
      return setImmediate(callback, new ConnectionError('Connection is closed.', 'ECONNCLOSED'))
    }

    this.canceled = false
    setImmediate(callback)
  }

  /**
   * Cancel currently executed request.
   *
   * @return {Boolean}
   */

  cancel () {
    this._cancel()
    return true
  }

  /**
   * @private
   */

  _cancel () {
    this.canceled = true
  }

  pause () {
    if (this.stream) {
      this._pause()
      return true
    }
    return false
  }

  _pause () {
    this._paused = true
  }

  resume () {
    if (this.stream) {
      this._resume()
      return true
    }
    return false
  }

  _resume () {
    this._paused = false
  }

  _setCurrentRequest (request) {
    this._currentRequest = request
    if (this._paused) {
      this.pause()
    }
    return this
  }
}

module.exports = Request
