import postgres from "postgres";
import { randomUUID } from "node:crypto";

type Sql = ReturnType<typeof postgres>;

export interface ListRow {
  id: string;
  name: string;
}

export interface TaskRow {
  id: string;
  list_id: string;
  title: string;
  description: string | null;
  source: string;
  consumed: boolean;
  created_at: Date;
  updated_at: Date;
}

export async function getLists(sql: Sql): Promise<ListRow[]> {
  return sql<ListRow[]>`select id, name from lists order by name`;
}

/** Full-replace catalog: upsert all supplied, delete any list not present (cascades tasks). */
export async function replaceLists(
  sql: Sql,
  lists: { id: string; name: string }[],
): Promise<void> {
  await sql.begin(async (tx) => {
    for (const l of lists) {
      await tx`
        insert into lists (id, name, updated_at)
        values (${l.id}, ${l.name}, now())
        on conflict (id) do update set name = excluded.name, updated_at = now()`;
    }
    if (lists.length) {
      const ids = lists.map((l) => l.id);
      await tx`delete from lists where id <> all(${ids})`;
    } else {
      await tx`delete from lists`;
    }
  });
}

export async function listExists(sql: Sql, id: string): Promise<boolean> {
  const rows = await sql`select 1 from lists where id = ${id}`;
  return rows.length > 0;
}

export async function getTasksForList(sql: Sql, listId: string): Promise<TaskRow[]> {
  return sql<TaskRow[]>`select * from tasks where list_id = ${listId} order by created_at`;
}

export async function createWebTask(
  sql: Sql,
  t: { listId: string; title: string; description: string | null },
): Promise<TaskRow> {
  const id = randomUUID();
  const [row] = await sql<TaskRow[]>`
    insert into tasks (id, list_id, title, description, source, consumed)
    values (${id}, ${t.listId}, ${t.title}, ${t.description}, 'web', false)
    returning *`;
  return row;
}

/** Idempotent upsert of a desktop Idle task by id. Returns whether a row was inserted. */
export async function upsertDesktopTask(
  sql: Sql,
  id: string,
  t: { listId: string; title: string; description?: string | null },
): Promise<{ created: boolean }> {
  const [row] = await sql<{ created: boolean }[]>`
    insert into tasks (id, list_id, title, description, source)
    values (${id}, ${t.listId}, ${t.title}, ${t.description ?? null}, 'desktop')
    on conflict (id) do update set
      list_id = excluded.list_id,
      title = excluded.title,
      description = excluded.description,
      updated_at = now()
    returning (xmax = 0) as created`;
  return { created: row.created };
}

/** Web-created tasks the desktop has not yet imported. */
export async function getUnconsumed(sql: Sql): Promise<TaskRow[]> {
  return sql<TaskRow[]>`
    select * from tasks where source = 'web' and consumed = false order by created_at`;
}

export async function consume(sql: Sql, id: string): Promise<boolean> {
  const res = await sql`update tasks set consumed = true, updated_at = now() where id = ${id}`;
  return res.count > 0;
}

export async function deleteTask(sql: Sql, id: string): Promise<void> {
  await sql`delete from tasks where id = ${id}`;
}