import { createLogger } from '@sim/logger'
import { toError } from '@sim/utils/errors'
import { secureFetchWithRetry } from '@/lib/knowledge/documents/secure-fetch.server'
import { VALIDATE_RETRY_OPTIONS } from '@/lib/knowledge/documents/utils'
import type { ConnectorConfig, ExternalDocument, ExternalDocumentList } from '@/connectors/types'
import { htmlToPlainText, joinTagArray, parseTagDate } from '@/connectors/utils'
import { DEFAULT_MAX_TICKETS, zendeskConnectorMeta } from '@/connectors/zendesk/meta'

const logger = createLogger('ZendeskConnector')

const ARTICLES_PER_PAGE = 30
const TICKETS_PER_PAGE = 100
const SEARCH_API_RESULT_CAP = 1000

const VALID_TICKET_STATUSES = new Set(['new', 'open', 'pending', 'hold', 'solved', 'closed'])

interface ZendeskArticle {
  id: number
  title: string
  body: string
  html_url: string
  section_id: number | null
  label_names: string[]
  author_id: number
  locale: string
  created_at: string
  updated_at: string
  edited_at: string
  draft: boolean
}

interface ZendeskTicket {
  id: number
  subject: string
  description: string
  status: string
  priority: string | null
  tags: string[]
  requester_id: number
  assignee_id: number | null
  created_at: string
  updated_at: string
}

interface ZendeskComment {
  id: number
  body: string
  html_body: string
  author_id: number
  created_at: string
  public: boolean
}

/**
 * Strict Zendesk subdomain label: a single DNS label of lowercase letters,
 * digits, and hyphens (not leading/trailing). Rejects anything that could
 * smuggle a scheme, host, path, port, or fragment into the base URL.
 */
const SUBDOMAIN_PATTERN = /^[a-z0-9](?:[a-z0-9-]{0,61}[a-z0-9])?$/

/**
 * Validates and normalizes a Zendesk subdomain.
 *
 * @throws {Error} when the subdomain is missing or not a valid DNS label.
 */
function normalizeSubdomain(subdomain: string): string {
  const normalized = subdomain.trim().toLowerCase()
  if (!SUBDOMAIN_PATTERN.test(normalized)) {
    throw new Error('Invalid Zendesk subdomain')
  }
  return normalized
}

/**
 * Builds the base URL for a Zendesk subdomain. The subdomain is validated to a
 * strict DNS label so it cannot be used to forge requests to arbitrary hosts.
 */
export function buildBaseUrl(subdomain: string): string {
  return `https://${normalizeSubdomain(subdomain)}.zendesk.com`
}

/**
 * Makes an authenticated GET request to the Zendesk API.
 * Uses email/token authentication.
 */
async function zendeskApiGet(
  url: string,
  accessToken: string,
  sourceConfig: Record<string, unknown>,
  retryOptions?: Parameters<typeof secureFetchWithRetry>[2]
): Promise<Record<string, unknown>> {
  const email = sourceConfig.email as string

  const response = await secureFetchWithRetry(
    url,
    {
      method: 'GET',
      headers: {
        Authorization: `Basic ${btoa(`${email}/token:${accessToken}`)}`,
        Accept: 'application/json',
      },
    },
    retryOptions
  )

  if (!response.ok) {
    throw new Error(`Zendesk API HTTP error: ${response.status}`)
  }

  return (await response.json()) as Record<string, unknown>
}

/**
 * Fetches all Help Center articles with pagination.
 */
async function fetchArticles(
  subdomain: string,
  accessToken: string,
  sourceConfig: Record<string, unknown>,
  locale?: string
): Promise<ZendeskArticle[]> {
  const allArticles: ZendeskArticle[] = []
  const baseUrl = buildBaseUrl(subdomain)
  const localePath = locale ? `/${encodeURIComponent(locale)}` : ''
  let page = 1

  while (true) {
    const url = `${baseUrl}/api/v2/help_center${localePath}/articles.json?page=${page}&per_page=${ARTICLES_PER_PAGE}`
    const data = await zendeskApiGet(url, accessToken, sourceConfig)
    const articles = (data.articles as ZendeskArticle[]) || []

    if (articles.length === 0) break

    allArticles.push(...articles)

    if (!data.next_page) break
    page++
  }

  return allArticles
}

/**
 * Fetches tickets with optional status filtering and pagination.
 */
async function fetchTickets(
  subdomain: string,
  accessToken: string,
  sourceConfig: Record<string, unknown>,
  statusFilter?: string,
  maxTickets?: number
): Promise<ZendeskTicket[]> {
  const allTickets: ZendeskTicket[] = []
  const baseUrl = buildBaseUrl(subdomain)
  const limit = maxTickets || DEFAULT_MAX_TICKETS
  let url: string | null = `${baseUrl}/api/v2/tickets.json?per_page=${TICKETS_PER_PAGE}`

  if (statusFilter && statusFilter !== 'all') {
    if (VALID_TICKET_STATUSES.has(statusFilter)) {
      if (limit > SEARCH_API_RESULT_CAP) {
        logger.warn(
          `Zendesk Search API caps at ${SEARCH_API_RESULT_CAP} results; requested limit ${limit} will be truncated. Remove status filter to use the unbounded tickets endpoint.`
        )
      }
      const params = new URLSearchParams({
        query: `type:ticket status:${statusFilter}`,
        per_page: String(TICKETS_PER_PAGE),
      })
      url = `${baseUrl}/api/v2/search.json?${params.toString()}`
    } else {
      logger.warn(
        `Invalid Zendesk statusFilter "${statusFilter}"; falling back to all tickets. Valid values: ${[...VALID_TICKET_STATUSES].join(', ')}.`
      )
    }
  }

  while (url && allTickets.length < limit) {
    const data = await zendeskApiGet(url, accessToken, sourceConfig)
    const tickets = ((data.tickets || data.results) as ZendeskTicket[]) || []

    if (tickets.length === 0) break

    allTickets.push(...tickets)

    url = (data.next_page as string) || null
  }

  return allTickets.slice(0, limit)
}

/**
 * Fetches all comments for a ticket.
 */
async function fetchTicketComments(
  subdomain: string,
  accessToken: string,
  sourceConfig: Record<string, unknown>,
  ticketId: number
): Promise<ZendeskComment[]> {
  const allComments: ZendeskComment[] = []
  const baseUrl = buildBaseUrl(subdomain)
  let url: string | null = `${baseUrl}/api/v2/tickets/${ticketId}/comments.json?per_page=100`

  while (url) {
    const data = await zendeskApiGet(url, accessToken, sourceConfig)
    const comments = (data.comments as ZendeskComment[]) || []

    allComments.push(...comments)

    url = (data.next_page as string) || null
  }

  return allComments
}

/**
 * Formats ticket with its comments into a single document content string.
 */
function formatTicketContent(ticket: ZendeskTicket, comments: ZendeskComment[]): string {
  const parts: string[] = []

  parts.push(`Subject: ${ticket.subject}`)
  parts.push(`Status: ${ticket.status}`)
  if (ticket.priority) {
    parts.push(`Priority: ${ticket.priority}`)
  }
  parts.push(`Created: ${ticket.created_at}`)
  parts.push(`Updated: ${ticket.updated_at}`)
  if (ticket.tags.length > 0) {
    parts.push(`Tags: ${ticket.tags.join(', ')}`)
  }
  parts.push('')
  parts.push('--- Description ---')
  parts.push(htmlToPlainText(ticket.description))

  if (comments.length > 0) {
    parts.push('')
    parts.push('--- Comments ---')
    for (const comment of comments) {
      const visibility = comment.public ? 'Public' : 'Internal'
      parts.push(`\n[${comment.created_at}] (${visibility}) Author ${comment.author_id}:`)
      parts.push(htmlToPlainText(comment.html_body || comment.body))
    }
  }

  return parts.join('\n')
}

/**
 * Converts an article to an ExternalDocument with inline content.
 * Articles return body inline from the list API so no deferral is needed.
 */
function articleToDocument(article: ZendeskArticle, subdomain: string): ExternalDocument {
  const content = htmlToPlainText(article.body || '')

  return {
    externalId: `article-${article.id}`,
    title: article.title,
    content,
    mimeType: 'text/plain',
    sourceUrl: article.html_url || `https://${subdomain}.zendesk.com/hc/articles/${article.id}`,
    contentHash: `zendesk:article:${article.id}:${article.updated_at}`,
    metadata: {
      type: 'article',
      articleId: article.id,
      sectionId: article.section_id,
      labels: article.label_names,
      author: String(article.author_id),
      locale: article.locale,
      draft: article.draft,
      createdAt: article.created_at,
      updatedAt: article.updated_at,
    },
  }
}

/**
 * Creates a deferred stub for a ticket. Content is not fetched here because
 * each ticket requires a separate comments API call. Full content is fetched
 * lazily via getDocument only for new/changed documents.
 */
function ticketToStub(ticket: ZendeskTicket, subdomain: string): ExternalDocument {
  return {
    externalId: `ticket-${ticket.id}`,
    title: `Ticket #${ticket.id}: ${ticket.subject}`,
    content: '',
    contentDeferred: true,
    mimeType: 'text/plain',
    sourceUrl: `https://${subdomain}.zendesk.com/agent/tickets/${ticket.id}`,
    contentHash: `zendesk:ticket:${ticket.id}:${ticket.updated_at}`,
    metadata: {
      type: 'ticket',
      ticketId: ticket.id,
      status: ticket.status,
      priority: ticket.priority,
      tags: ticket.tags,
      createdAt: ticket.created_at,
      updatedAt: ticket.updated_at,
    },
  }
}

/**
 * Converts a ticket (with comments) to a full ExternalDocument.
 * Used by getDocument to resolve deferred ticket stubs.
 */
function ticketToDocument(
  ticket: ZendeskTicket,
  comments: ZendeskComment[],
  subdomain: string
): ExternalDocument {
  const content = formatTicketContent(ticket, comments)

  return {
    externalId: `ticket-${ticket.id}`,
    title: `Ticket #${ticket.id}: ${ticket.subject}`,
    content,
    contentDeferred: false,
    mimeType: 'text/plain',
    sourceUrl: `https://${subdomain}.zendesk.com/agent/tickets/${ticket.id}`,
    contentHash: `zendesk:ticket:${ticket.id}:${ticket.updated_at}`,
    metadata: {
      type: 'ticket',
      ticketId: ticket.id,
      status: ticket.status,
      priority: ticket.priority,
      tags: ticket.tags,
      commentCount: comments.length,
      createdAt: ticket.created_at,
      updatedAt: ticket.updated_at,
    },
  }
}

export const zendeskConnector: ConnectorConfig = {
  ...zendeskConnectorMeta,

  listDocuments: async (
    accessToken: string,
    sourceConfig: Record<string, unknown>,
    _cursor?: string,
    _syncContext?: Record<string, unknown>
  ): Promise<ExternalDocumentList> => {
    const subdomain = (sourceConfig.subdomain as string)?.trim()
    if (!subdomain) {
      throw new Error('Subdomain is required')
    }

    const email = sourceConfig.email as string
    if (!email?.trim()) {
      throw new Error('Email is required')
    }

    const contentType = (sourceConfig.contentType as string) || 'both'
    const ticketStatus = sourceConfig.ticketStatus as string | undefined
    const locale = (sourceConfig.locale as string)?.trim() || undefined
    const maxTickets = sourceConfig.maxTickets
      ? Number(sourceConfig.maxTickets)
      : DEFAULT_MAX_TICKETS

    const documents: ExternalDocument[] = []

    if (contentType === 'articles' || contentType === 'both') {
      logger.info('Fetching Zendesk Help Center articles', { subdomain, locale })
      const articles = await fetchArticles(subdomain, accessToken, sourceConfig, locale)
      logger.info(`Fetched ${articles.length} articles from Zendesk`)

      for (const article of articles) {
        if (!article.body?.trim()) continue
        documents.push(articleToDocument(article, subdomain))
      }
    }

    if (contentType === 'tickets' || contentType === 'both') {
      logger.info('Fetching Zendesk support tickets', { subdomain, ticketStatus, maxTickets })
      const tickets = await fetchTickets(
        subdomain,
        accessToken,
        sourceConfig,
        ticketStatus,
        maxTickets
      )
      logger.info(`Fetched ${tickets.length} tickets from Zendesk`)

      for (const ticket of tickets) {
        documents.push(ticketToStub(ticket, subdomain))
      }
    }

    return {
      documents,
      hasMore: false,
    }
  },

  getDocument: async (
    accessToken: string,
    sourceConfig: Record<string, unknown>,
    externalId: string
  ): Promise<ExternalDocument | null> => {
    const subdomain = (sourceConfig.subdomain as string)?.trim()
    if (!subdomain) return null

    try {
      if (externalId.startsWith('article-')) {
        const articleId = externalId.replace('article-', '')
        const baseUrl = buildBaseUrl(subdomain)
        const url = `${baseUrl}/api/v2/help_center/articles/${articleId}.json`
        const data = await zendeskApiGet(url, accessToken, sourceConfig)
        const article = data.article as ZendeskArticle
        if (!article) return null
        return articleToDocument(article, subdomain)
      }

      if (externalId.startsWith('ticket-')) {
        const ticketId = Number(externalId.replace('ticket-', ''))
        const baseUrl = buildBaseUrl(subdomain)
        const url = `${baseUrl}/api/v2/tickets/${ticketId}.json`
        const data = await zendeskApiGet(url, accessToken, sourceConfig)
        const ticket = data.ticket as ZendeskTicket
        if (!ticket) return null
        const comments = await fetchTicketComments(subdomain, accessToken, sourceConfig, ticketId)
        return ticketToDocument(ticket, comments, subdomain)
      }

      return null
    } catch (error) {
      logger.warn('Failed to get Zendesk document', {
        externalId,
        error: toError(error).message,
      })
      return null
    }
  },

  validateConfig: async (
    accessToken: string,
    sourceConfig: Record<string, unknown>
  ): Promise<{ valid: boolean; error?: string }> => {
    const subdomain = (sourceConfig.subdomain as string)?.trim()
    if (!subdomain) {
      return { valid: false, error: 'Subdomain is required' }
    }

    const email = (sourceConfig.email as string)?.trim()
    if (!email) {
      return { valid: false, error: 'Email is required' }
    }

    const contentType = sourceConfig.contentType as string | undefined
    if (!contentType) {
      return { valid: false, error: 'Content type is required' }
    }

    const maxTickets = sourceConfig.maxTickets as string | undefined
    if (maxTickets && (Number.isNaN(Number(maxTickets)) || Number(maxTickets) <= 0)) {
      return { valid: false, error: 'Max tickets must be a positive number' }
    }

    try {
      const baseUrl = buildBaseUrl(subdomain)
      const url = `${baseUrl}/api/v2/users/me.json`
      await zendeskApiGet(url, accessToken, sourceConfig, VALIDATE_RETRY_OPTIONS)
      return { valid: true }
    } catch (error) {
      return { valid: false, error: toError(error).message || 'Failed to validate configuration' }
    }
  },

  mapTags: (metadata: Record<string, unknown>): Record<string, unknown> => {
    const result: Record<string, unknown> = {}

    if (typeof metadata.type === 'string') {
      result.contentType = metadata.type
    }

    if (typeof metadata.status === 'string') {
      result.status = metadata.status
    }

    if (typeof metadata.priority === 'string') {
      result.priority = metadata.priority
    }

    const labels = joinTagArray(metadata.labels)
    if (labels) {
      result.labels = labels
    }

    const tags = joinTagArray(metadata.tags)
    if (tags) {
      result.tags = tags
    }

    const updatedAt = parseTagDate(metadata.updatedAt)
    if (updatedAt) {
      result.updatedAt = updatedAt
    }

    if (typeof metadata.commentCount === 'number') {
      result.commentCount = metadata.commentCount
    }

    return result
  },
}