/**
 * Serves the comments on dumps. Comments are broadcast over the WebSocket as
 * they are posted, edited and deleted, to everyone, or to its poster alone for
 * a private dump, whose comments 404 for anyone else.
 *
 * - `GET /api/dumps/:dumpId/comments` — optional sign-in. Answers every comment
 *   on a dump, oldest first.
 * - `POST /api/dumps/:dumpId/comments` — signed in. Posts a comment, replying
 *   to `parentId` if given.
 * - `PATCH /api/comments/:commentId` — signed in, as its author or with
 *   `comment:moderate`. Edits a comment.
 * - `GET /api/comments/:commentId/likers?page=&limit=` — optional sign-in.
 *   Answers a page of the users who like a comment.
 * - `DELETE /api/comments/:commentId` — signed in, as its author or with
 *   `comment:moderate`. Deletes a comment, leaving its place in the thread.
 *
 * @module
 */

import { Router } from "@oak/oak";
import { type APIResponse, type PaginatedData } from "../../shared/api.ts";
import { APIException } from "../lib/api-exception.ts";
import type { Comment } from "../../shared/comment.ts";
import {
  isCreateCommentRequest,
  isUpdateCommentRequest,
} from "../validators/comment.ts";
import type { PublicUser } from "../../shared/user.ts";
import { toPublicUser } from "../model/user.ts";
import { authMiddleware } from "../middleware/auth.ts";
import { can } from "../lib/permissions.ts";
import { parseOptionalAuth } from "../lib/auth.ts";
import { parsePagination } from "../lib/pagination.ts";
import {
  createComment,
  deleteComment,
  getCommentDumpId,
  getComments,
  updateComment,
} from "../services/comment-service.ts";
import { getCommentLikers } from "../services/comment-like-service.ts";
import { getDump } from "../services/dump-service.ts";
import {
  broadcastCommentCreated,
  broadcastCommentDeleted,
  broadcastCommentUpdated,
} from "../services/ws-service.ts";

/**
 * Mounted by `api/main.ts` behind the error, Open Graph and CORS middleware.
 * An `APIException` thrown by a handler becomes the JSON error response there.
 */
const router: Router = new Router({ prefix: "/api" });

router.get("/dumps/:dumpId/comments", async (ctx) => {
  const requestingUserId = await parseOptionalAuth(ctx) ?? undefined;
  const dump = getDump(ctx.params.dumpId, requestingUserId);
  const comments = getComments(dump.id);
  const responseBody: APIResponse<Comment[]> = {
    success: true,
    data: comments,
  };
  ctx.response.body = responseBody;
});

router.post("/dumps/:dumpId/comments", authMiddleware, async (ctx) => {
  const userId = ctx.state.user.userId;
  const dump = getDump(ctx.params.dumpId, userId);
  const body: unknown = await ctx.request.body.json();
  if (!isCreateCommentRequest(body)) {
    throw new APIException(400, "Invalid comment data");
  }
  const comment = createComment(
    dump.id,
    userId,
    body.body,
    body.parentId ?? undefined,
  );
  broadcastCommentCreated(comment, dump);
  const responseBody: APIResponse<Comment> = { success: true, data: comment };
  ctx.response.status = 201;
  ctx.response.body = responseBody;
});

router.patch("/comments/:commentId", authMiddleware, async (ctx) => {
  const userId = ctx.state.user.userId;
  const canModerate = can(ctx.state.user, "comment:moderate");
  const body: unknown = await ctx.request.body.json();
  if (!isUpdateCommentRequest(body)) {
    throw new APIException(400, "Invalid comment data");
  }
  const { comment, dump } = updateComment(
    ctx.params.commentId,
    body.body,
    userId,
    canModerate,
  );
  broadcastCommentUpdated(comment, dump);
  const responseBody: APIResponse<Comment> = { success: true, data: comment };
  ctx.response.body = responseBody;
});

router.get("/comments/:commentId/likers", async (ctx) => {
  const requestingUserId = await parseOptionalAuth(ctx) ?? undefined;
  const dumpId = getCommentDumpId(ctx.params.commentId);
  getDump(dumpId, requestingUserId); // 404s unless the caller may see the dump.
  const { page, limit } = parsePagination(ctx.request.url.searchParams);
  const { items, hasMore } = getCommentLikers(
    ctx.params.commentId,
    page,
    limit,
  );
  const responseBody: APIResponse<PaginatedData<PublicUser>> = {
    success: true,
    data: {
      items: items.map(toPublicUser),
      hasMore,
    },
  };
  ctx.response.body = responseBody;
});

router.delete("/comments/:commentId", authMiddleware, (ctx) => {
  const userId = ctx.state.user.userId;
  const canModerate = can(ctx.state.user, "comment:moderate");
  const dump = deleteComment(
    ctx.params.commentId,
    userId,
    canModerate,
  );
  broadcastCommentDeleted(ctx.params.commentId, dump);
  const responseBody: APIResponse<null> = { success: true, data: null };
  ctx.response.body = responseBody;
});

export default router;