import { nextCursor, slackRequest } from './request.ts'
import { boundedLimit, inputRecord, optionalBoolean, optionalString } from './validation.ts'

const allowedTypes = new Set(['public_channel', 'private_channel', 'im', 'mpim'])

type ConversationsResponse = {
  ok: boolean
  channels?: unknown[]
  response_metadata?: { next_cursor?: string }
  [key: string]: unknown
}

/** List conversations available to the authorizing Slack user. */
export default async function listConversations(params: Record<string, unknown> = {}) {
  const input = inputRecord(params)
  const requestedTypes = input.types ?? ['public_channel', 'private_channel', 'im', 'mpim']
  if (!Array.isArray(requestedTypes) || requestedTypes.some((type) => typeof type !== 'string' || !allowedTypes.has(type))) {
    throw new Error('types must contain only public_channel, private_channel, im, or mpim.')
  }

  const result = await slackRequest<ConversationsResponse>('users.conversations', {
    types: requestedTypes.join(','),
    limit: boundedLimit(input.limit),
    cursor: optionalString(input, 'cursor'),
    exclude_archived: optionalBoolean(input, 'excludeArchived') ?? true,
  })

  return {
    conversations: result.channels ?? [],
    nextCursor: nextCursor(result),
  }
}