/**
 * The `chat_messages` table: its row type, its guard, and its mapper to the
 * API's {@link ChatMessage}.
 *
 * @module
 */

import type { SQLOutputValue } from "node:sqlite";
import type { ChatMessage } from "../../shared/chat.ts";

/**
 * A row of the `chat_messages` table, joined with its author and, when it is
 * a reply, the replied-to message and its author.
 */
export interface ChatMessageRow {
  /** The message's id. */
  id: string;
  /** The author's id. */
  user_id: string;
  /** The message, in Markdown. */
  body: string;
  /** When the message was sent. */
  created_at: string;
  /** When the message was last edited, if ever. */
  updated_at: string | null;
  /** The author's name (joined). */
  author_username: string;
  /** The author's avatar type, null without one (joined). */
  author_avatar_mime: string | null;
  /**
   * The id of the message this replies to, kept even once that message is
   * deleted.
   */
  reply_to_id: string | null;
  /**
   * The replied-to message's author (joined); null when there's no reply or it
   * was since deleted.
   */
  reply_to_author: string | null;
  /**
   * The start of the replied-to message (joined); null when there's no reply or
   * it was since deleted.
   */
  reply_to_body: string | null;
  /** Any other column the query selects. */
  [key: string]: SQLOutputValue;
}

/** Checks whether `obj` is a {@link ChatMessageRow}. */
export function isChatMessageRow(obj: unknown): obj is ChatMessageRow {
  return !!obj && typeof obj === "object" &&
    "id" in obj && typeof obj.id === "string" &&
    "user_id" in obj && typeof obj.user_id === "string" &&
    "body" in obj && typeof obj.body === "string" &&
    "created_at" in obj && typeof obj.created_at === "string" &&
    "updated_at" in obj &&
    (typeof obj.updated_at === "string" || obj.updated_at === null) &&
    "author_username" in obj && typeof obj.author_username === "string" &&
    "author_avatar_mime" in obj &&
    (typeof obj.author_avatar_mime === "string" ||
      obj.author_avatar_mime === null) &&
    "reply_to_id" in obj &&
    (typeof obj.reply_to_id === "string" || obj.reply_to_id === null) &&
    "reply_to_author" in obj &&
    (typeof obj.reply_to_author === "string" || obj.reply_to_author === null) &&
    "reply_to_body" in obj &&
    (typeof obj.reply_to_body === "string" || obj.reply_to_body === null);
}

/** Converts a row to the API's {@link ChatMessage}. */
export function chatMessageRowToApi(row: ChatMessageRow): ChatMessage {
  return {
    id: row.id,
    userId: row.user_id,
    body: row.body,
    createdAt: new Date(row.created_at),
    updatedAt: row.updated_at ? new Date(row.updated_at) : undefined,
    authorUsername: row.author_username,
    authorAvatarMime: row.author_avatar_mime ?? undefined,
    replyToId: row.reply_to_id ?? undefined,
    replyToAuthor: row.reply_to_author ?? undefined,
    replyToBody: row.reply_to_body ?? undefined,
  };
}