/**
 * Adds likes on comments, as the `comment_likes` table and a `like_count` on
 * each comment that comment-like-service keeps in step, so that listing
 * comments doesn't count their likes.
 *
 * @module
 */

import type { DatabaseSync } from "node:sqlite";

/**
 * Run once by `runMigrations`. Existing comments start with no likes, and a
 * database made from schema.sql already has both.
 */
export function up(db: DatabaseSync): void {
  const commentCols = db.prepare(`PRAGMA table_info(comments);`).all() as {
    name: string;
  }[];
  if (!commentCols.some((c) => c.name === "like_count")) {
    db.exec(
      `ALTER TABLE comments ADD COLUMN like_count INTEGER NOT NULL DEFAULT 0;`,
    );
  }

  db.exec(`CREATE TABLE IF NOT EXISTS comment_likes (
    comment_id TEXT NOT NULL,
    user_id    TEXT NOT NULL,
    created_at TEXT NOT NULL,
    PRIMARY KEY (comment_id, user_id),
    FOREIGN KEY (comment_id) REFERENCES comments(id) ON DELETE CASCADE,
    FOREIGN KEY (user_id)    REFERENCES users(id)    ON DELETE CASCADE
  );`);

  db.exec(
    `CREATE INDEX IF NOT EXISTS idx_comment_likes_user ON comment_likes(user_id);`,
  );
}