/**
 * Maps the `dumps` table to the API's {@link Dump}. Every service that reads
 * dumps selects them with the column lists here, checks each row with
 * {@link isDumpRow} and converts it with {@link dumpRowToApi}.
 *
 * @module
 */

import type { SQLOutputValue } from "node:sqlite";
import type { Dump, RichContent } from "../../shared/dump.ts";

/**
 * Read from the `dumps` table with {@link DUMP_SELECT_COLUMNS}, or written back
 * from a {@link Dump} by {@link dumpApiToRow}. It lacks `url_canonical`, which
 * only the duplicate lookup reads.
 */
export interface DumpRow {
  id: string;
  kind: string;
  title: string;
  comment: string | null;
  user_id: string;
  created_at: string;
  updated_at: string | null;
  slug: string | null;
  /** The link as the poster submitted it. */
  url: string | null;
  /** {@link RichContent} as JSON. */
  rich_content: string | null;
  file_name: string | null;
  file_mime: string | null;
  file_size: number | null;
  vote_count: number;
  /** Computed by a subquery, which counts the comments that aren't deleted. */
  comment_count: number;
  is_private: number;
  custom_thumbnail_mime: string | null;
  /** Lets a query select more columns, such as a join's. */
  [key: string]: SQLOutputValue;
}

/**
 * Lists the stored columns of {@link DumpRow}. A column added to the table must
 * be added here, to {@link DumpRow} and to {@link isDumpRow}.
 */
export const DUMP_COLUMNS =
  "id, kind, title, slug, comment, user_id, created_at, updated_at, url, rich_content, file_name, file_mime, file_size, vote_count, is_private, custom_thumbnail_mime";

// The same columns, for a query that aliases `dumps` as `d`.
const DUMP_COLUMNS_ALIASED = DUMP_COLUMNS.split(", ").map((c) => `d.${c}`)
  .join(", ");

/**
 * Selects a whole {@link DumpRow}, the stored columns and the computed
 * `comment_count`.
 */
export const DUMP_SELECT_COLUMNS: string = `${DUMP_COLUMNS},
  (SELECT COUNT(*) FROM comments WHERE dump_id = dumps.id AND deleted = 0) as comment_count`;

/**
 * Selects a whole {@link DumpRow} in a query that aliases `dumps` as `d` to
 * join it with other tables.
 */
export const DUMP_SELECT_COLUMNS_ALIASED: string = `${DUMP_COLUMNS_ALIASED},
  (SELECT COUNT(*) FROM comments WHERE dump_id = d.id AND deleted = 0) as comment_count`;

/**
 * Checks whether `obj`, a row from a query, is a {@link DumpRow}. It checks
 * each column's type, not that `kind` is `url` or `file`.
 */
export function isDumpRow(obj: unknown): obj is DumpRow {
  return !!obj &&
    typeof obj === "object" &&
    "id" in obj && typeof obj.id === "string" &&
    "kind" in obj && typeof obj.kind === "string" &&
    "title" in obj && typeof obj.title === "string" &&
    "comment" in obj &&
    (typeof obj.comment === "string" || obj.comment === null) &&
    "user_id" in obj && typeof obj.user_id === "string" &&
    "created_at" in obj && typeof obj.created_at === "string" &&
    "updated_at" in obj &&
    (typeof obj.updated_at === "string" || obj.updated_at === null) &&
    "slug" in obj && (typeof obj.slug === "string" || obj.slug === null) &&
    "url" in obj && (typeof obj.url === "string" || obj.url === null) &&
    "rich_content" in obj &&
    (typeof obj.rich_content === "string" || obj.rich_content === null) &&
    "file_name" in obj &&
    (typeof obj.file_name === "string" || obj.file_name === null) &&
    "file_mime" in obj &&
    (typeof obj.file_mime === "string" || obj.file_mime === null) &&
    "file_size" in obj &&
    (typeof obj.file_size === "number" || obj.file_size === null) &&
    "vote_count" in obj && typeof obj.vote_count === "number" &&
    "comment_count" in obj && typeof obj.comment_count === "number" &&
    "is_private" in obj && typeof obj.is_private === "number" &&
    "custom_thumbnail_mime" in obj &&
    (typeof obj.custom_thumbnail_mime === "string" ||
      obj.custom_thumbnail_mime === null);
}

/**
 * Converts a row to the API's {@link Dump}, parsing its preview's JSON. It
 * leaves `categoryIds` out: the services add them with `attachCategoryIds`.
 */
export function dumpRowToApi(row: DumpRow): Dump {
  return {
    id: row.id,
    kind: row.kind as "url" | "file",
    title: row.title,
    slug: row.slug ?? undefined,
    url: row.url ?? undefined,
    comment: row.comment ?? undefined,
    userId: row.user_id,
    createdAt: new Date(row.created_at),
    updatedAt: row.updated_at ? new Date(row.updated_at) : undefined,
    richContent: row.rich_content
      ? (JSON.parse(row.rich_content) as RichContent)
      : undefined,
    fileName: row.file_name ?? undefined,
    fileMime: row.file_mime ?? undefined,
    fileSize: row.file_size ?? undefined,
    voteCount: row.vote_count,
    commentCount: row.comment_count,
    isPrivate: Boolean(row.is_private),
    thumbnailMime: row.custom_thumbnail_mime ?? undefined,
  };
}

/**
 * Converts a {@link Dump} back to a row, for a service that writes an edited
 * dump's columns.
 */
export function dumpApiToRow(dump: Dump): DumpRow {
  return {
    id: dump.id,
    kind: dump.kind,
    title: dump.title,
    slug: dump.slug ?? null,
    comment: dump.comment ?? null,
    user_id: dump.userId,
    created_at: dump.createdAt.toISOString(),
    updated_at: dump.updatedAt?.toISOString() ?? null,
    url: dump.url ?? null,
    rich_content: dump.richContent ? JSON.stringify(dump.richContent) : null,
    file_name: dump.fileName ?? null,
    file_mime: dump.fileMime ?? null,
    file_size: dump.fileSize ?? null,
    vote_count: dump.voteCount,
    comment_count: dump.commentCount,
    is_private: dump.isPrivate ? 1 : 0,
    custom_thumbnail_mime: dump.thumbnailMime ?? null,
  };
}