import { describe, it, expect, vi, beforeEach, afterEach, type MockInstance } from 'vitest';
import { Command } from 'commander';
import { registerRuntimeLaunchers, type RuntimeLaunchHandler } from './launch.js';

/**
 * Tests for the commander wiring between `mosaic <runtime>` / `mosaic yolo <runtime>`
 * subcommands and the internal `launchRuntime` dispatcher.
 *
 * Regression target: see mosaicstack/stack#454 — before the fix, `mosaic yolo claude`
 * passed the literal string "claude" as an excess positional argument to the
 * underlying CLI, which Claude Code then interpreted as the first user message.
 *
 * The bug existed because Commander.js includes declared positional arguments
 * (here `<runtime>`) in `cmd.args` alongside any true excess args. The action
 * handler must slice them off before forwarding.
 */

function buildProgram(handler: RuntimeLaunchHandler): Command {
  const program = new Command();
  program.exitOverride(); // prevent process.exit on parse errors
  registerRuntimeLaunchers(program, handler);
  return program;
}

// `process.exit` returns `never`, so vi.spyOn demands a replacement with the
// same signature. We throw from the mock to short-circuit into test-land.
const exitThrows = (): never => {
  throw new Error('process.exit called');
};

describe('registerRuntimeLaunchers — non-yolo subcommands', () => {
  let mockExit: MockInstance<typeof process.exit>;

  beforeEach(() => {
    // process.exit is called when the yolo action rejects an invalid runtime.
    // Stub it so the assertion catches the rejection instead of terminating
    // the test runner.
    mockExit = vi.spyOn(process, 'exit').mockImplementation(exitThrows);
  });

  afterEach(() => {
    mockExit.mockRestore();
  });

  it.each(['claude', 'codex', 'opencode', 'pi'] as const)(
    'forwards %s with empty extraArgs and yolo=false',
    (runtime) => {
      const handler = vi.fn();
      const program = buildProgram(handler);
      program.parse(['node', 'mosaic', runtime]);

      expect(handler).toHaveBeenCalledTimes(1);
      expect(handler).toHaveBeenCalledWith(runtime, [], false);
    },
  );

  it('forwards excess args after a non-yolo runtime subcommand', () => {
    const handler = vi.fn();
    const program = buildProgram(handler);
    program.parse(['node', 'mosaic', 'claude', '--print', 'hello']);

    expect(handler).toHaveBeenCalledWith('claude', ['--print', 'hello'], false);
  });
});

describe('registerRuntimeLaunchers — yolo <runtime>', () => {
  let mockExit: MockInstance<typeof process.exit>;
  let mockError: MockInstance<typeof console.error>;

  beforeEach(() => {
    mockExit = vi.spyOn(process, 'exit').mockImplementation(exitThrows);
    mockError = vi.spyOn(console, 'error').mockImplementation(() => {});
  });

  afterEach(() => {
    mockExit.mockRestore();
    mockError.mockRestore();
  });

  it.each(['claude', 'codex', 'opencode', 'pi'] as const)(
    'does NOT pass the runtime name as an extra arg (regression #454) for yolo %s',
    (runtime) => {
      const handler = vi.fn();
      const program = buildProgram(handler);
      program.parse(['node', 'mosaic', 'yolo', runtime]);

      expect(handler).toHaveBeenCalledTimes(1);
      // The critical assertion: extraArgs must be empty, not [runtime].
      // Before the fix, cmd.args was [runtime] and the runtime name leaked
      // through to the underlying CLI as an initial positional argument.
      expect(handler).toHaveBeenCalledWith(runtime, [], true);
    },
  );

  it('forwards true excess args after a yolo runtime', () => {
    const handler = vi.fn();
    const program = buildProgram(handler);
    program.parse(['node', 'mosaic', 'yolo', 'claude', '--print', 'hi']);

    expect(handler).toHaveBeenCalledWith('claude', ['--print', 'hi'], true);
  });

  it('rejects an unknown runtime under yolo without invoking the handler', () => {
    const handler = vi.fn();
    const program = buildProgram(handler);

    expect(() => program.parse(['node', 'mosaic', 'yolo', 'bogus'])).toThrow('process.exit called');
    expect(handler).not.toHaveBeenCalled();
    expect(mockExit).toHaveBeenCalledWith(1);
  });
});