import {
  getRuntimeStateJson,
  setRuntimeStateJson,
  withImmediateTransaction,
} from "./sdk-runtime-state-db.js";

const DATABASE_LOCK_KEY = "databaseLock";

interface DatabaseLock {
  isLocked: boolean;
  lockedBy: string;
  lockedAt: string | null;
}

const defaultLock = (): DatabaseLock => ({
  isLocked: false,
  lockedBy: "",
  lockedAt: null,
});

function readLock(): DatabaseLock {
  return getRuntimeStateJson<DatabaseLock>(DATABASE_LOCK_KEY) ?? defaultLock();
}

/**
 * Gets the current database lock state
 * @returns The current database lock state
 */
export const getDatabaseLock = (): DatabaseLock => {
  return readLock();
};

/**
 * Attempts to acquire the database lock
 * @param processName Name of the process requesting the lock
 * @returns true if lock was acquired, false if database is already locked
 */
export const acquireDatabaseLock = (processName: string): boolean => {
  return withImmediateTransaction(() => {
    const currentLock = readLock();
    if (currentLock.isLocked) {
      return false;
    }

    setRuntimeStateJson(DATABASE_LOCK_KEY, {
      isLocked: true,
      lockedBy: processName,
      lockedAt: new Date().toISOString(),
    });
    return true;
  });
};

/**
 * Releases the database lock
 * @param processName Name of the process releasing the lock
 * @returns true if lock was released, false if process doesn't own the lock
 */
export const releaseDatabaseLock = (processName: string): boolean => {
  return withImmediateTransaction(() => {
    const currentLock = readLock();
    if (!currentLock.isLocked || currentLock.lockedBy !== processName) {
      return false;
    }

    setRuntimeStateJson(DATABASE_LOCK_KEY, defaultLock());
    return true;
  });
};

/**
 * Checks if the database is available for use
 * @returns true if database is available, false if locked
 */
export const isDatabaseAvailable = (): boolean => {
  return !readLock().isLocked;
};