import { Router, Request, Response } from 'express';
import { existsSync, readFileSync } from 'fs';
import { join } from 'path';
import { type Repository, type Job, localTaskRepoName } from '../db/repository.js';
import { logger } from '../logger.js';
import { canViewTask } from './local-api-helpers.js';

const MAX_ACTIVITY_LOG_CHARS = 4000;

function readActivityLog(worktreePath: string | null, maxChars: number = 0): string {
  if (!worktreePath) return '';
  const logPath = join(worktreePath, 'logs', 'activity.log');
  if (!existsSync(logPath)) return '';
  try {
    const content = readFileSync(logPath, 'utf-8');
    return maxChars > 0 && content.length > maxChars
      ? content.slice(-maxChars)
      : content;
  } catch {
    return '';
  }
}

export function createSubtaskActivityRouter(repo: Repository): Router {
  const router = Router();

  // GET /:id/subtasks/activities — bulk fetch all subtask activities (includes nested subtasks)
  router.get('/:id/subtasks/activities', async (req: Request, res: Response) => {
    try {
      const taskId = Number(req.params.id);
      const viewer = req.user as Express.User | undefined;
      const task = await repo.getLocalTask(taskId, viewer ? { viewer } : undefined);
      if (!canViewTask(req, res, task)) return;

      const latestJob = await repo.getLatestJobForIssue(localTaskRepoName(taskId), taskId);
      if (!latestJob) { res.status(404).json({ error: 'No job found' }); return; }

      // 再帰的に全サブジョブ（孫含む）を収集
      const collectAllSubJobs = async (parentId: string): Promise<Job[]> => {
        const jobs = await repo.getSubJobs(parentId);
        const result = [...jobs];
        for (const job of jobs) {
          if (job.status === 'waiting_subtasks') {
            result.push(...await collectAllSubJobs(job.id));
          }
        }
        return result;
      };
      const allJobs = await collectAllSubJobs(latestJob.id);

      const subtasks = allJobs.map(job => ({
        jobId: job.id,
        issueNumber: job.issueNumber,
        status: job.status,
        currentMovement: job.currentMovement ?? null,
        currentActivity: job.currentActivity ?? null,
        activityLog: readActivityLog(job.worktreePath, MAX_ACTIVITY_LOG_CHARS),
      }));

      res.json({ subtasks });
    } catch (err) {
      logger.error(`Subtask activities API error: ${err}`);
      res.status(500).json({ error: 'Failed to fetch subtask activities' });
    }
  });

  // GET /:id/subtasks/:jobId/activity — individual subtask activity (supports nested subtasks)
  router.get('/:id/subtasks/:jobId/activity', async (req: Request, res: Response) => {
    try {
      const taskId = Number(req.params.id);
      const jobId = req.params.jobId;

      const viewer = (req.user as Express.User | undefined) ?? undefined;
      const task = await repo.getLocalTask(taskId, viewer ? { viewer } : undefined);
      if (!canViewTask(req, res, task)) return;

      // jobId で直接取得（孫タスクにも対応）
      const job = await repo.getJob(jobId, viewer ? { viewer } : undefined);
      if (!job || !job.worktreePath) { res.status(404).json({ error: 'Subtask not found' }); return; }

      // タスクのワークスペース配下であることを確認
      if (task!.workspacePath && !job.worktreePath.startsWith(task!.workspacePath)) {
        res.status(404).json({ error: 'Subtask not found' }); return;
      }

      res.json({ activityLog: readActivityLog(job.worktreePath) });
    } catch (err) {
      logger.error(`Subtask activity API error: ${err}`);
      res.status(500).json({ error: 'Failed to fetch subtask activity' });
    }
  });

  return router;
}