import { randomUUID } from 'node:crypto';
import { getRun, start } from 'workflow/api';
import type { WorkflowRunStatus } from '@workflow/world';
import type { Task, TaskStatus, TaskTimeline, TaskType } from '@/lib/types';
import { runTaskWorkflow } from '@/app/workflows/task-runner';
import { describeTaskFailure } from '@/lib/server/task-errors';
import {
  countTasksByStatus,
  createTaskRunRecord,
  findInFlightTaskByResourceKey,
  getTaskByIdForUser,
  listTaskStageEventsForTask,
  listRecentTasksForUser,
  markTaskFailure,
  setTaskStatusFromWorkflow,
  setTaskWorkflowRunId,
  updateTaskNotificationState
} from '@/lib/server/repos/tasks';
import { buildTaskNotification } from '@/lib/server/task-notifications';

type EnqueueTaskInput = {
  userId: string;
  taskType: TaskType;
  payload?: Record<string, unknown>;
  priority?: number;
  maxAttempts?: number;
  resourceKey?: string;
};

type UpdateTaskNotificationInput = {
  read?: boolean;
  silenced?: boolean;
};

function mapWorkflowStatus(status: WorkflowRunStatus): TaskStatus {
  switch (status) {
    case 'pending':
      return 'queued';
    case 'running':
      return 'running';
    case 'completed':
      return 'completed';
    case 'failed':
    case 'cancelled':
      return 'failed';
    default:
      return 'failed';
  }
}

function isProjectionPendingSync(task: Task) {
  return task.status === 'queued' || task.status === 'running';
}

async function reconcileTaskWithWorkflow(task: Task) {
  if (!task.workflow_run_id || !isProjectionPendingSync(task)) {
    return task;
  }

  try {
    const run = getRun(task.workflow_run_id);
    const workflowStatus = await run.status;
    const nextStatus = mapWorkflowStatus(workflowStatus);

    if (nextStatus === task.status) {
      return task;
    }

    const failure = nextStatus === 'failed'
      ? describeTaskFailure(task, workflowStatus === 'cancelled' ? 'Workflow run cancelled' : 'Workflow run failed')
      : null;

    const updated = await setTaskStatusFromWorkflow(
      task.id,
      nextStatus,
      failure?.detail ?? null,
      failure?.summary ?? null
    );

    const fallbackTask = {
      ...task,
      status: nextStatus,
      stage: nextStatus,
      stage_detail: nextStatus === 'failed' ? (failure?.summary ?? 'The background workflow stopped unexpectedly.') : 'Workflow run completed.',
      stage_context: null,
      error: failure?.detail ?? null,
      finished_at: nextStatus === 'queued' || nextStatus === 'running'
        ? null
        : task.finished_at ?? new Date().toISOString()
    } satisfies Omit<Task, 'notification'>;

    return updated ?? {
      ...fallbackTask,
      notification: buildTaskNotification(fallbackTask)
    };
  } catch {
    return task;
  }
}

export async function enqueueTask(input: EnqueueTaskInput) {
  const task = await createTaskRunRecord({
    id: randomUUID(),
    user_id: input.userId,
    task_type: input.taskType,
    payload: input.payload ?? {},
    priority: input.priority ?? 50,
    max_attempts: input.maxAttempts ?? 3,
    resource_key: input.resourceKey ?? null
  });

  try {
    const run = await start(runTaskWorkflow, [task.id]);
    await setTaskWorkflowRunId(task.id, run.runId);

    return {
      ...task,
      workflow_run_id: run.runId
    } satisfies Task;
  } catch (error) {
    const failure = describeTaskFailure(task, 'Failed to start workflow');
    await markTaskFailure(task.id, failure.detail, 'failed', {
      detail: failure.summary
    });

    const wrapped = new Error(failure.detail);
    (wrapped as Error & { cause?: unknown }).cause = error;
    throw wrapped;
  }
}

export async function findInFlightTask(userId: string, taskType: TaskType, resourceKey: string) {
  const task = await findInFlightTaskByResourceKey(userId, taskType, resourceKey);

  if (!task) {
    return null;
  }

  return await reconcileTaskWithWorkflow(task);
}

export async function getTaskById(taskId: string, userId: string) {
  const task = await getTaskByIdForUser(taskId, userId);

  if (!task) {
    return null;
  }

  return await reconcileTaskWithWorkflow(task);
}

export async function listRecentTasks(userId: string, limit = 20, statuses?: TaskStatus[]) {
  const tasks = await listRecentTasksForUser(userId, limit, statuses);
  return await Promise.all(tasks.map((task) => reconcileTaskWithWorkflow(task)));
}

export async function updateTaskNotification(
  userId: string,
  taskId: string,
  input: UpdateTaskNotificationInput
) {
  const task = await updateTaskNotificationState(taskId, userId, input);
  if (!task) {
    return null;
  }

  return await reconcileTaskWithWorkflow(task);
}

export async function getTaskTimeline(taskId: string, userId: string): Promise<TaskTimeline | null> {
  const task = await getTaskById(taskId, userId);
  if (!task) {
    return null;
  }

  const events = await listTaskStageEventsForTask(taskId, userId);

  return {
    task,
    events
  };
}

export async function getTaskQueueSnapshot() {
  return await countTasksByStatus();
}