import type { VmSandboxHandle } from "@suaveplan/api-sandbox-vm";
import {
    SAND_VM_BRIDGE_CODES,
    SandboxVmBridgeError,
} from "../error-codes/error-codes.js";

/**
 * Idempotent lifecycle forwarder around a `VmSandboxHandle`. Wraps
 * `start` so a second call is a silent no-op (the underlying sandbox
 * has already evaluated its module) and wraps `dispose` so a second
 * call is also a no-op (the sandbox's own `isDisposed()` would short-
 * circuit, but having the guard at the bridge layer means the host
 * never sees a stray throw if a future sandbox impl tightens its
 * behaviour).
 *
 * Underlying-handle failures are re-wrapped as
 * `SAND_VM_BRIDGE.LIFECYCLE_FAILED` with the original error preserved
 * as `cause`.
 */
export interface SandboxLifecycleForwarder {
    readonly start: () => Promise<void>;
    readonly dispose: () => void;
    readonly hasStarted: () => boolean;
    readonly isDisposed: () => boolean;
}

/**
 * Build the idempotent lifecycle forwarder around a `VmSandboxHandle`.
 */
export function createSandboxLifecycleForwarder(
    sandbox: VmSandboxHandle
): SandboxLifecycleForwarder {
    let started = false;
    let disposed = false;

    return Object.freeze({
        async start(): Promise<void> {
            if (started) return;
            if (disposed) {
                throw new SandboxVmBridgeError(
                    SAND_VM_BRIDGE_CODES.LIFECYCLE_FAILED,
                    "cannot start a disposed sandbox bridge"
                );
            }
            try {
                await sandbox.start();
            } catch (err) {
                throw new SandboxVmBridgeError(
                    SAND_VM_BRIDGE_CODES.LIFECYCLE_FAILED,
                    "sandbox start failed",
                    { cause: err }
                );
            }
            started = true;
        },
        dispose(): void {
            if (disposed) return;
            disposed = true;
            try {
                sandbox.dispose();
            } catch (err) {
                throw new SandboxVmBridgeError(
                    SAND_VM_BRIDGE_CODES.LIFECYCLE_FAILED,
                    "sandbox dispose failed",
                    { cause: err }
                );
            }
        },
        hasStarted(): boolean {
            return started;
        },
        isDisposed(): boolean {
            return disposed;
        },
    });
}