import { createError } from 'h3'
import { getPostgresClient } from './postgres-client'

/**
 * @typedef {Object} PostComment
 * @property {string} id - 댓글 ID
 * @property {string} postId - 게시물 ID
 * @property {string | null} parentId - 부모 댓글 ID
 * @property {string} body - 댓글 내용
 * @property {string} status - 댓글 상태
 * @property {string} createdAt - 생성 시각
 * @property {string} updatedAt - 수정 시각
 * @property {{ id: string, username: string }} user - 작성자 정보
 */

/**
 * DB 클라이언트 조회 (선택)
 * @returns {ReturnType<typeof import('postgres').default> | null} postgres sql 클라이언트
 */
const getSql = () => getPostgresClient()

/**
 * 게시물 ID 조회
 * @param {ReturnType<typeof import('postgres').default>} sql - postgres 클라이언트
 * @param {string} slug - 게시물 슬러그
 * @returns {Promise<string | null>} 게시물 ID
 */
const findPublishedPostIdBySlug = async (sql, slug) => {
  const rows = await sql`
    SELECT id
    FROM posts
    WHERE slug = ${slug}
      AND status = 'published'
      AND (
        published_at IS NULL
        OR published_at <= now()
      )
    LIMIT 1
  `

  return rows?.[0]?.id || null
}

/**
 * 게시물 댓글 조회
 * @param {string} slug - 게시물 슬러그
 * @returns {Promise<Array<PostComment>>} 댓글 목록
 */
export const listPostCommentsBySlug = async (slug) => {
  const sql = getSql()

  if (!sql) {
    return []
  }

  const postId = await findPublishedPostIdBySlug(sql, slug)
  if (!postId) {
    throw createError({
      statusCode: 404,
      statusMessage: '게시물을 찾을 수 없습니다'
    })
  }

  const rows = await sql`
    SELECT
      comments.id,
      comments.post_id AS "postId",
      comments.parent_id AS "parentId",
      comments.body,
      comments.status,
      comments.created_at AS "createdAt",
      comments.updated_at AS "updatedAt",
      users.id AS "userId",
      users.username AS "username"
    FROM comments
    INNER JOIN users ON users.id = comments.user_id
    WHERE comments.post_id = ${postId}
      AND comments.status = 'published'
    ORDER BY comments.created_at ASC
  `

  return rows.map((row) => ({
    id: row.id,
    postId: row.postId,
    parentId: row.parentId || null,
    body: row.body,
    status: row.status,
    createdAt: row.createdAt.toISOString(),
    updatedAt: row.updatedAt.toISOString(),
    user: {
      id: row.userId,
      username: row.username
    }
  }))
}

/**
 * 댓글 생성
 * @param {{ slug: string, userId: string, body: string, parentId?: string | null }} input - 댓글 입력값
 * @returns {Promise<PostComment>} 생성된 댓글
 */
export const createComment = async (input) => {
  const sql = getSql()

  if (!sql) {
    throw createError({
      statusCode: 500,
      message: '데이터베이스 설정이 필요합니다.'
    })
  }

  const postId = await findPublishedPostIdBySlug(sql, input.slug)
  if (!postId) {
    throw createError({
      statusCode: 404,
      statusMessage: '게시물을 찾을 수 없습니다'
    })
  }

  let parentId = input.parentId || null

  if (parentId) {
    const parentRows = await sql`
      SELECT id, post_id AS "postId", parent_id AS "parentId", status
      FROM comments
      WHERE id = ${parentId}
      LIMIT 1
    `
    const parent = parentRows?.[0]

    if (!parent || parent.postId !== postId || parent.status !== 'published') {
      throw createError({
        statusCode: 400,
        message: '유효하지 않은 부모 댓글입니다.'
      })
    }

    if (parent.parentId) {
      throw createError({
        statusCode: 400,
        message: '대댓글에는 추가 답글을 달 수 없습니다.'
      })
    }
  }

  const rows = await sql`
    INSERT INTO comments (post_id, user_id, parent_id, body, status)
    VALUES (${postId}, ${input.userId}, ${parentId}, ${input.body}, 'published')
    RETURNING
      id,
      post_id AS "postId",
      parent_id AS "parentId",
      body,
      status,
      created_at AS "createdAt",
      updated_at AS "updatedAt"
  `

  const created = rows?.[0]
  if (!created) {
    throw createError({
      statusCode: 500,
      message: '댓글 생성에 실패했습니다.'
    })
  }

  const userRows = await sql`
    SELECT id, username
    FROM users
    WHERE id = ${input.userId}
    LIMIT 1
  `

  const user = userRows?.[0]
  if (!user) {
    throw createError({
      statusCode: 401,
      message: '회원 정보를 찾을 수 없습니다.'
    })
  }

  return {
    id: created.id,
    postId: created.postId,
    parentId: created.parentId || null,
    body: created.body,
    status: created.status,
    createdAt: created.createdAt.toISOString(),
    updatedAt: created.updatedAt.toISOString(),
    user: {
      id: user.id,
      username: user.username
    }
  }
}