export enum TaskStatus {
  WAITING = 'waiting',
  PENDING = 'pending',
  RUNNING = 'running',
  RATE_LIMITED = 'rate_limited',
  WAITING_ANSWER = 'waiting_answer',
  COMPLETED = 'completed',
  FAILED = 'failed',
  TIMED_OUT = 'timed_out',
  CANCELLED = 'cancelled',
  UNKNOWN = 'unknown',
}

export const TERMINAL_STATUSES: ReadonlySet<TaskStatus> = new Set([
  TaskStatus.COMPLETED,
  TaskStatus.FAILED,
  TaskStatus.CANCELLED,
  TaskStatus.TIMED_OUT,
  TaskStatus.UNKNOWN,
]);

export function isTerminalStatus(status: TaskStatus): boolean {
  return TERMINAL_STATUSES.has(status);
}

export type TaskTypeName = 'coder' | 'planner' | 'tester' | 'researcher' | 'general';

export type Provider = 'codex' | 'copilot' | 'claude-cli';

// ---------------------------------------------------------------------------
// PendingQuestion — discriminated union for 5 pause-flow question variants
// Spec reference: §3.3
// ---------------------------------------------------------------------------

export type PendingQuestion =
  | {
      type: 'user_input';
      requestId: string;
      questions: Array<{
        id: string;
        text: string;
        options?: string[];
        allowFreeform?: boolean;
      }>;
    }
  | {
      type: 'command_approval';
      requestId: string;
      command: string;
      sandboxPolicy?: string;
    }
  | {
      type: 'file_approval';
      requestId: string;
      fileChanges: Array<{ path: string; patch: string }>;
    }
  | {
      type: 'elicitation';
      requestId: string;
      serverName?: string;
      message: string;
      schema?: unknown;
    }
  | {
      type: 'dynamic_tool';
      requestId: string;
      toolName: string;
      arguments: string;
    };

export type PendingQuestionType = PendingQuestion['type'];

// ---------------------------------------------------------------------------
// TaskState — complete in-memory representation of a task
// Spec reference: §3.2 (data model), §4.1 (FSM states)
// ---------------------------------------------------------------------------

export interface TaskState {
  // Identity
  id: string;
  status: TaskStatus;
  provider: Provider;
  taskType: TaskTypeName;

  // Execution
  prompt: string;
  cwd: string;
  model?: string;
  effort?: 'low' | 'medium' | 'high' | 'xhigh';
  sessionId?: string;
  operationId?: string;

  // Lifecycle timestamps
  createdAt: string;
  updatedAt: string;
  startedAt?: string;
  completedAt?: string;
  lastOutputAt?: string;
  timeoutMs?: number;
  timeoutAt?: string;
  keepAlive?: number;

  // Output
  output: string[];
  outputFilePath?: string;

  // Dependencies & labels
  dependsOn?: string[];
  labels: string[];

  // Pause state
  pendingQuestions: PendingQuestion[];

  // Error tracking
  error?: string;
  exitCode?: number;
  result?: unknown;

  // Token usage from last thread/tokenUsage/updated event
  tokenUsage?: {
    totalTokens: number;
    inputTokens: number;
    outputTokens: number;
    contextWindow: number | null;
  };

  // Recovery markers
  recovered?: boolean;
  degraded?: boolean;
}