import type { Db } from "@wrnexus/db";
import type { Job } from "./index.ts";
import type { QueueJobRecord, QueueStore } from "./durable.ts";

const SAFE = /^[A-Za-z_][A-Za-z0-9_]*$/;
const check = (value: string) => {
  if (!SAFE.test(value)) throw new TypeError(`Invalid queue table: ${value}`);
  return value;
};

export async function installDatabaseQueueSchema(db: Db, table = "wrnexus_jobs") {
  const target = check(table);
  await db.exec(`CREATE TABLE IF NOT EXISTS ${target} (
    id VARCHAR(191) PRIMARY KEY, name VARCHAR(191) NOT NULL, payload TEXT NOT NULL,
    run_at BIGINT NOT NULL, priority INTEGER NOT NULL DEFAULT 0,
    idempotency_key VARCHAR(191), lease_owner VARCHAR(191), lease_until BIGINT
  )`);
  await db.exec(`CREATE TABLE IF NOT EXISTS ${target}_history (
    id VARCHAR(191) PRIMARY KEY, name VARCHAR(191) NOT NULL, state VARCHAR(32) NOT NULL,
    payload TEXT NOT NULL, error TEXT, finished_at BIGINT NOT NULL
  )`);
  for (const statement of [
    `CREATE INDEX ${target}_due ON ${target} (run_at, priority)`,
    `CREATE UNIQUE INDEX ${target}_idempotency ON ${target} (name, idempotency_key)`,
  ]) {
    try {
      await db.exec(statement);
    } catch (error) {
      if (!/exist|duplicate|already/i.test(String(error))) throw error;
    }
  }
}

export function databaseQueueStore(db: Db, table = "wrnexus_jobs"): QueueStore {
  const target = check(table);
  type Row = { payload: string };
  const decode = (row: Row) => JSON.parse(row.payload) as Job;
  return {
    async put(job) {
      if (db.driver.dialect === "mysql") {
        await db.exec(
          `INSERT INTO ${target} (id,name,payload,run_at,priority,idempotency_key,lease_owner,lease_until)
          VALUES (?,?,?,?,?,?,NULL,NULL) ON DUPLICATE KEY UPDATE name=VALUES(name),payload=VALUES(payload),run_at=VALUES(run_at),priority=VALUES(priority),lease_owner=NULL,lease_until=NULL`,
          [
            job.id,
            job.name,
            JSON.stringify(job),
            job.runAt,
            job.priority,
            job.idempotencyKey ?? null,
          ],
        );
      } else {
        await db.exec(
          `INSERT INTO ${target} (id,name,payload,run_at,priority,idempotency_key,lease_owner,lease_until)
          VALUES (?,?,?,?,?,?,NULL,NULL) ON CONFLICT(id) DO UPDATE SET name=excluded.name,payload=excluded.payload,run_at=excluded.run_at,priority=excluded.priority,lease_owner=NULL,lease_until=NULL`,
          [
            job.id,
            job.name,
            JSON.stringify(job),
            job.runAt,
            job.priority,
            job.idempotencyKey ?? null,
          ],
        );
      }
    },
    async get(id) {
      const row = await db.one<Row>(`SELECT payload FROM ${target} WHERE id = ?`, [id]);
      return row ? decode(row) : null;
    },
    async remove(id) {
      await db.exec(`DELETE FROM ${target} WHERE id = ?`, [id]);
    },
    async due(now, limit) {
      return (
        await db.all<Row>(
          `SELECT payload FROM ${target} WHERE run_at <= ? AND (lease_until IS NULL OR lease_until < ?) ORDER BY priority DESC,run_at LIMIT ?`,
          [now, now, limit],
        )
      ).map(decode);
    },
    async list(name) {
      return (
        await db.all<Row>(
          `SELECT payload FROM ${target}${name ? " WHERE name = ?" : ""} ORDER BY run_at`,
          name ? [name] : [],
        )
      ).map(decode);
    },
    async findByIdempotencyKey(name, key) {
      const row = await db.one<Row>(
        `SELECT payload FROM ${target} WHERE name = ? AND idempotency_key = ?`,
        [name, key],
      );
      return row ? decode(row) : null;
    },
    async size() {
      return Number(
        (await db.one<{ total: number | string }>(`SELECT COUNT(*) AS total FROM ${target}`))
          ?.total ?? 0,
      );
    },
    async claim(id, worker, leaseUntil, now = Date.now()) {
      return (
        (
          await db.exec(
            `UPDATE ${target} SET lease_owner=?,lease_until=? WHERE id=? AND (lease_until IS NULL OR lease_until < ?)`,
            [worker, leaseUntil, id, now],
          )
        ).changes > 0
      );
    },
    async release(id, worker) {
      await db.exec(
        `UPDATE ${target} SET lease_owner=NULL,lease_until=NULL WHERE id=? AND lease_owner=?`,
        [id, worker],
      );
    },
    async archive(record) {
      const values = [
        record.job.id,
        record.job.name,
        record.state,
        JSON.stringify(record.job),
        record.error ?? null,
        record.finishedAt,
      ];
      if (db.driver.dialect === "mysql")
        await db.exec(
          `INSERT INTO ${target}_history (id,name,state,payload,error,finished_at) VALUES (?,?,?,?,?,?) ON DUPLICATE KEY UPDATE state=VALUES(state),payload=VALUES(payload),error=VALUES(error),finished_at=VALUES(finished_at)`,
          values,
        );
      else
        await db.exec(
          `INSERT INTO ${target}_history (id,name,state,payload,error,finished_at) VALUES (?,?,?,?,?,?) ON CONFLICT(id) DO UPDATE SET state=excluded.state,payload=excluded.payload,error=excluded.error,finished_at=excluded.finished_at`,
          values,
        );
    },
    async history(id) {
      const rows = await db.all<{
        state: QueueJobRecord["state"];
        payload: string;
        error: string | null;
        finished_at: number;
      }>(
        `SELECT state,payload,error,finished_at FROM ${target}_history${id ? " WHERE id = ?" : ""} ORDER BY finished_at DESC`,
        id ? [id] : [],
      );
      return rows.map((row) => ({
        job: JSON.parse(row.payload),
        state: row.state,
        error: row.error ?? undefined,
        finishedAt: Number(row.finished_at),
      }));
    },
  };
}