// SPDX-FileCopyrightText: 2024 John Livingston <https://www.john-livingston.fr/>
//
// SPDX-License-Identifier: AGPL-3.0-only

import type { RegisterServerOptions } from '@peertube/peertube-types'
import type { ChannelConfigurationOptions } from '../../../../shared/lib/types'
import {
  channelTermsMaxLength,
  forbidSpecialCharsMaxTolerance,
  forbidSpecialCharsDefaultTolerance,
  noDuplicateDefaultDelay,
  noDuplicateMaxDelay
} from '../../../../shared/lib/constants'
import * as RE2 from 're2'

type SanitizeMode = 'validation' | 'read'

/**
 * Sanitize data so that they can safely be used/stored for channel configuration configuration.
 * Throw an error if the format is obviously wrong.
 * Cleans data (removing empty values, ...)
 * @param options Peertube server options
 * @param _channelInfos Channel infos
 * @param data Input data
 * @param mode Sanitization mode. 'validation': when verifiying user input. 'read': when reading from disk.
 */
async function sanitizeChannelConfigurationOptions (
  _options: RegisterServerOptions,
  _channelId: number | string,
  data: unknown,
  mode: SanitizeMode
): Promise<ChannelConfigurationOptions> {
  if (!_assertObjectType(data)) {
    throw new Error('Invalid data type')
  }

  const botData = data.bot ?? {}
  if (!_assertObjectType(botData)) {
    throw new Error('Invalid data.bot data type')
  }

  // slowMode not present in livechat <= 8.2.0:
  const slowModeData = data.slowMode ?? {}
  if (!_assertObjectType(slowModeData)) {
    throw new Error('Invalid data.slowMode data type')
  }
  slowModeData.duration ??= slowModeData.defaultDuration ?? 0 // v8.3.0 to 8.3.2: was in defaultDuration

  const moderationData = data.moderation ?? {} // comes with livechat 10.3.0
  if (!_assertObjectType(moderationData)) {
    throw new Error('Invalid data.moderation data type')
  }
  moderationData.delay ??= 0
  moderationData.anonymize ??= false // comes with livechat 11.0.0

  // mute not present in livechat <= 10.2.0
  const mute = data.mute ?? {}
  if (!_assertObjectType(mute)) {
    throw new Error('Invalid data.mute data type')
  }
  mute.anonymous ??= false

  // forbidSpecialChars comes with livechat 12.0.0
  botData.forbidSpecialChars ??= {
    enabled: false,
    reason: '',
    tolerance: forbidSpecialCharsDefaultTolerance,
    applyToModerators: false
  }
  if (!_assertObjectType(botData.forbidSpecialChars)) {
    throw new Error('Invalid data.bot.forbidSpecialChars data type')
  }

  // noDuplicate comes with livechat 12.0.0
  botData.noDuplicate ??= {
    enabled: false,
    reason: '',
    delay: noDuplicateDefaultDelay,
    applyToModerators: false
  }
  if (!_assertObjectType(botData.noDuplicate)) {
    throw new Error('Invalid data.bot.noDuplicate data type')
  }

  // terms not present in livechat <= 10.2.0
  let terms = data.terms ?? undefined
  if (terms !== undefined && (typeof terms !== 'string')) {
    throw new Error('Invalid data.terms data type')
  }
  if (terms && terms.length > channelTermsMaxLength) {
    throw new Error('data.terms value too long')
  }
  if (terms === '') { terms = undefined }

  const result: ChannelConfigurationOptions = {
    bot: {
      enabled: _readBoolean(botData, 'enabled'),
      nickname: _readSimpleInput(botData, 'nickname', true),
      forbiddenWords: await _readForbiddenWords(botData, mode),
      forbidSpecialChars: await _readForbidSpecialChars(botData),
      noDuplicate: await _readNoDuplicate(botData),
      quotes: _readQuotes(botData),
      commands: _readCommands(botData)
      // TODO: bannedJIDs
    },
    slowMode: {
      duration: _readInteger(slowModeData, 'duration', 0, 1000)
    },
    mute: {
      anonymous: _readBoolean(mute, 'anonymous')
    },
    moderation: {
      delay: _readInteger(moderationData, 'delay', 0, 60),
      anonymize: _readBoolean(moderationData, 'anonymize')
    }
  }
  if (terms !== undefined) {
    result.terms = terms
  }

  return result
}

function _assertObjectType (data: unknown): data is Record<string, unknown> {
  return !!data && (typeof data === 'object') && Object.keys(data).every(k => typeof k === 'string')
}

function _readBoolean (data: Record<string, unknown>, f: string): boolean {
  if (!(f in data)) {
    return false
  }
  if (typeof data[f] !== 'boolean') {
    throw new Error('Invalid data type for field ' + f)
  }
  return data[f]
}

function _readInteger (data: Record<string, unknown>, f: string, min: number, max: number): number {
  if (!(f in data)) {
    throw new Error('Missing integer value for field ' + f)
  }
  const v = typeof data[f] === 'number' ? Math.trunc(data[f]) : parseInt(data[f] as string)
  if (isNaN(v)) {
    throw new Error('Invalid value type for field ' + f)
  }
  if (v < min) {
    throw new Error('Invalid value type (<min) for field ' + f)
  }
  if (v > max) {
    throw new Error('Invalid value type (>max) for field ' + f)
  }
  return v
}

function _readSimpleInput (data: Record<string, unknown>, f: string, strict?: boolean, noSpace?: boolean): string {
  if (!(f in data)) {
    return ''
  }
  if (typeof data[f] !== 'string') {
    throw new Error('Invalid data type for field ' + f)
  }
  // Removing control characters.
  // eslint-disable-next-line no-control-regex
  let s = data[f].replace(/[\u0000-\u001F\u007F-\u009F]/g, '')
  if (strict) {
    // Replacing all invalid characters, no need to throw an error..
    s = s.replace(/[^\p{L}\p{N}\p{Z}_-]$/gu, '')
  }
  if (noSpace) {
    s = s.replace(/\s+/g, '')
  }
  return s
}

function _readStringArray (data: Record<string, unknown>, f: string): string[] {
  if (!(f in data)) {
    return []
  }
  if (!Array.isArray(data[f])) {
    throw new Error('Invalid data type for field ' + f)
  }
  const result: string[] = []
  for (const v of data[f]) {
    if (typeof v !== 'string') {
      throw new Error('Invalid data type in a value of field ' + f)
    }
    if (v === '' || /^\s+$/.test(v)) {
      // ignore empty values
      continue
    }
    result.push(v)
  }
  return result
}

function _readMultiLineString (data: Record<string, unknown>, f: string): string {
  if (!(f in data)) {
    return ''
  }
  if (typeof data[f] !== 'string') {
    throw new Error('Invalid data type for field ' + f)
  }
  // Removing control characters (must authorize \u001A: line feed)
  // eslint-disable-next-line no-control-regex
  const s = data[f].replace(/[\u0000-\u0009\u001B-\u001F\u007F-\u009F]/g, '')
  return s
}

async function _readRegExpArray (data: Record<string, unknown>, f: string, mode: SanitizeMode): Promise<string[]> {
  // Note: this function can instanciate a lot of RegExp.
  // To avoid freezing the server, we make it async, and will validate each regexp in a separate tick.
  if (!(f in data)) {
    return []
  }
  if (!Array.isArray(data[f])) {
    throw new Error('Invalid data type for field ' + f)
  }
  const result: string[] = []
  for (const v of data[f]) {
    if (typeof v !== 'string') {
      throw new Error('Invalid data type in a value of field ' + f)
    }
    if (v === '' || /^\s+$/.test(v)) {
      // ignore empty values
      continue
    }
    // value must be a valid RE2 regexp
    try {
      async function _validate (v: string): Promise<void> {
        // Before livechat v13, the bot was using RegExp.
        // Now it is using RE2, to avoid ReDOS attacks.
        // RE2 does not accept all regular expressions.
        // So, here come the question about settings saved before...
        // So we introduce the "mode" parameter.
        // When reading from disk, we want to be more permissive.
        // When validating frontend data, we want to be more restrictive.
        // Note: the bot will simply ignore any invalid RE2 expression, and generate an error log on loading.
        if (mode === 'read') {
          // eslint-disable-next-line no-new
          new RegExp(v)
        } else {
          // eslint-disable-next-line no-new, new-cap
          new RE2.default(v)
        }
      }
      await _validate(v)
    } catch (err: any) {
      throw new ChannelConfigurationValidationError('Invalid value in field ' + f, err.toString() as string)
    }
    result.push(v)
  }
  return result
}

async function _readForbiddenWords (
  botData: Record<string, unknown>,
  mode: SanitizeMode
): Promise<ChannelConfigurationOptions['bot']['forbiddenWords']> {
  if (!Array.isArray(botData.forbiddenWords)) {
    throw new Error('Invalid forbiddenWords data')
  }
  const result: ChannelConfigurationOptions['bot']['forbiddenWords'] = []
  for (const fw of botData.forbiddenWords) {
    if (!_assertObjectType(fw)) {
      throw new Error('Invalid entry in botData.forbiddenWords')
    }
    const regexp = !!fw.regexp
    let entries
    if (regexp) {
      entries = await _readRegExpArray(fw, 'entries', mode)
    } else {
      entries = _readStringArray(fw, 'entries')
    }
    const applyToModerators = _readBoolean(fw, 'applyToModerators')
    const label = fw.label ? _readSimpleInput(fw, 'label') : undefined
    const reason = fw.reason ? _readSimpleInput(fw, 'reason') : undefined
    const comments = fw.comments ? _readMultiLineString(fw, 'comments') : undefined

    result.push({
      regexp,
      entries,
      applyToModerators,
      label,
      reason,
      comments
    })
  }
  return result
}

async function _readForbidSpecialChars (
  botData: Record<string, unknown>
): Promise<ChannelConfigurationOptions['bot']['forbidSpecialChars']> {
  if (!_assertObjectType(botData.forbidSpecialChars)) {
    throw new Error('Invalid forbidSpecialChars data')
  }
  const result: ChannelConfigurationOptions['bot']['forbidSpecialChars'] = {
    enabled: _readBoolean(botData.forbidSpecialChars, 'enabled'),
    reason: _readSimpleInput(botData.forbidSpecialChars, 'reason'),
    tolerance: _readInteger(botData.forbidSpecialChars, 'tolerance', 0, forbidSpecialCharsMaxTolerance),
    applyToModerators: _readBoolean(botData.forbidSpecialChars, 'applyToModerators')
  }
  return result
}

async function _readNoDuplicate (
  botData: Record<string, unknown>
): Promise<ChannelConfigurationOptions['bot']['noDuplicate']> {
  if (!_assertObjectType(botData.noDuplicate)) {
    throw new Error('Invalid forbidSpecialChars data')
  }
  const result: ChannelConfigurationOptions['bot']['noDuplicate'] = {
    enabled: _readBoolean(botData.noDuplicate, 'enabled'),
    reason: _readSimpleInput(botData.noDuplicate, 'reason'),
    delay: _readInteger(botData.noDuplicate, 'delay', 0, noDuplicateMaxDelay),
    applyToModerators: _readBoolean(botData.noDuplicate, 'applyToModerators')
  }
  return result
}

function _readQuotes (botData: Record<string, unknown>): ChannelConfigurationOptions['bot']['quotes'] {
  if (!Array.isArray(botData.quotes)) {
    throw new Error('Invalid quotes data')
  }
  const result: ChannelConfigurationOptions['bot']['quotes'] = []
  for (const qs of botData.quotes) {
    if (!_assertObjectType(qs)) {
      throw new Error('Invalid entry in botData.quotes')
    }
    const messages = _readStringArray(qs, 'messages')
    const delay = _readInteger(qs, 'delay', 1, 6000)

    result.push({
      messages,
      delay
    })
  }
  return result
}

function _readCommands (botData: Record<string, unknown>): ChannelConfigurationOptions['bot']['commands'] {
  if (!Array.isArray(botData.commands)) {
    throw new Error('Invalid commands data')
  }
  const result: ChannelConfigurationOptions['bot']['commands'] = []
  for (const cs of botData.commands) {
    if (!_assertObjectType(cs)) {
      throw new Error('Invalid entry in botData.commands')
    }
    const message = _readSimpleInput(cs, 'message')
    const command = _readSimpleInput(cs, 'command', false, true)

    result.push({
      message,
      command
    })
  }
  return result
}

class ChannelConfigurationValidationError extends Error {
  /**
   * The message for the frontend.
   */
  public validationErrorMessage: string

  constructor (message: string | undefined, validationErrorMessage: string) {
    super(message)
    this.validationErrorMessage = validationErrorMessage
  }
}

export {
  sanitizeChannelConfigurationOptions
}