# -*- coding: utf-8 -*-
"""
任务执行引擎：后台线程执行单次 LLM 调用，记录日志与成本，
完成后进入「待审核」或直接「已完成」。
"""
import threading
import traceback
import db
import llm_gateway
import config


def _log(task_id, level, message):
    try:
        db.w('INSERT INTO task_logs (task_id, level, message, created_at) VALUES (?,?,?,?)',
             (task_id, level, message, db.now()))
    except Exception:
        pass


def _set_task(task_id, **fields):
    if not fields:
        return
    fields['updated_at'] = db.now()
    sets = ', '.join(f'{k}=?' for k in fields)
    db.w(f'UPDATE tasks SET {sets} WHERE id=?', (*fields.values(), task_id))


def _cost_record(task, worker, usage):
    db.w(
        'INSERT INTO cost_records (task_id, project_id, worker_id, provider, model, '
        'prompt_tokens, completion_tokens, total_tokens, cost, created_at) '
        'VALUES (?,?,?,?,?,?,?,?,?,?)',
        (task['id'], task['project_id'], worker['id'], worker['provider'],
         worker['model'], usage['prompt_tokens'], usage['completion_tokens'],
         usage['total_tokens'], usage['cost'], db.now()))


def pick_worker_auto(task):
    """自动路由：按模型输入单价升序挑选 enabled Worker"""
    rows = db.q('SELECT * FROM workers WHERE status="enabled" ORDER BY id')
    if not rows:
        return None
    best, best_price = None, None
    for r in rows:
        pin, pout = llm_gateway.model_price(r['model'])
        price = pin + pout * 0.5
        if best_price is None or price < best_price:
            best, best_price = r, price
    return best


def check_worker_limits(worker):
    """成本上限预检：返回 (ok, reason)"""
    if worker['task_cost_limit'] and worker['task_cost_limit'] > 0:
        used = db.task_worker_cost(worker['id'])
        if used >= worker['task_cost_limit']:
            return False, f'该 Worker 累计成本 {used:.4f} 元已达单任务上限 {worker["task_cost_limit"]} 元'
    if worker['monthly_cost_limit'] and worker['monthly_cost_limit'] > 0:
        used = db.monthly_worker_cost(worker['id'])
        if used >= worker['monthly_cost_limit']:
            return False, f'该 Worker 本月成本 {used:.4f} 元已达月度上限 {worker["monthly_cost_limit"]} 元'
    return True, ''


def _check_project_budget(task):
    proj = db.q('SELECT * FROM projects WHERE id=?', (task['project_id'],), one=True)
    if proj and proj['budget_limit'] and proj['budget_limit'] > 0:
        rows = db.q('SELECT COALESCE(SUM(cost),0) AS t FROM cost_records WHERE project_id=?',
                    (task['project_id'],))
        used = rows[0]['t'] if rows else 0
        if used >= proj['budget_limit']:
            return False, f'项目预算已用完（{used:.2f}/{proj["budget_limit"]:.2f} 元）'
    return True, ''


def run_task(task_id):
    """在后台线程中执行任务"""
    task = db.q('SELECT * FROM tasks WHERE id=?', (task_id,), one=True)
    if not task:
        return
    if task['status'] == 'running':
        return

    # 确定 Worker
    worker = None
    if task['worker_id']:
        worker = db.q('SELECT * FROM workers WHERE id=?', (task['worker_id'],), one=True)
        if not worker or worker['status'] != 'enabled':
            _set_task(task_id, status='failed', error='指定 Worker 不存在或已停用',
                      finished_at=db.now())
            _log(task_id, 'error', '指定 Worker 不存在或已停用')
            return
    else:
        worker = pick_worker_auto(task)
        if not worker:
            _set_task(task_id, status='failed', error='无可用 Worker（自动路由失败）',
                      finished_at=db.now())
            _log(task_id, 'error', '自动路由失败：无可用 Worker')
            return
        _set_task(task_id, worker_id=worker['id'])
        _log(task_id, 'info', f'自动路由 → Worker「{worker["name"]}」（{worker["provider"]}/{worker["model"]}）')

    # 预算/成本预检
    ok, reason = check_worker_limits(worker)
    if not ok:
        _set_task(task_id, status='failed', error=reason, finished_at=db.now())
        _log(task_id, 'error', reason)
        return
    ok, reason = _check_project_budget(task)
    if not ok:
        _set_task(task_id, status='failed', error=reason, finished_at=db.now())
        _log(task_id, 'error', reason)
        return

    _set_task(task_id, status='running', started_at=db.now(), error='')
    _log(task_id, 'info', f'开始执行：Worker「{worker["name"]}」 模型 {worker["provider"]}/{worker["model"]}')

    messages = []
    if worker['system_prompt']:
        messages.append({'role': 'system', 'content': worker['system_prompt']})
    messages.append({'role': 'user', 'content': task['description'] or task['title']})

    try:
        usage = llm_gateway.chat(
            worker['provider'], worker['model'], messages,
            temperature=worker['temperature'], max_tokens=worker['max_tokens'],
            base_url=worker['base_url'] or None, api_key=worker['api_key'] or None)
    except Exception as e:
        _set_task(task_id, status='failed', error=str(e), finished_at=db.now())
        _log(task_id, 'error', f'执行失败: {e}')
        return

    _cost_record(task, worker, usage)
    _log(task_id, 'success',
         f'执行完成：{usage["total_tokens"]} tokens（输入 {usage["prompt_tokens"]} / 输出 {usage["completion_tokens"]}），'
         f'成本 ¥{usage["cost"]:.6f}')

    new_status = 'review' if task['review_required'] else 'done'
    fields = {
        'status': new_status,
        'output_text': usage['text'],
        'output_version': task['output_version'] + 1,
        'finished_at': db.now(),
    }
    _set_task(task_id, **fields)
    if new_status == 'review':
        _log(task_id, 'info', '产出已提交，等待人工审核（HITL）')
    else:
        _log(task_id, 'success', '任务完成（无需审核）')


class TaskRunner:
    def __init__(self):
        self._threads = {}

    def submit(self, task_id):
        if task_id in self._threads and self._threads[task_id].is_alive():
            return False
        t = threading.Thread(target=self._safe_run, args=(task_id,), daemon=True)
        self._threads[task_id] = t
        t.start()
        return True

    def _safe_run(self, task_id):
        try:
            run_task(task_id)
        except Exception:
            _log(task_id, 'error', '引擎异常: ' + traceback.format_exc())
            try:
                _set_task(task_id, status='failed', error='引擎异常，见日志', finished_at=db.now())
            except Exception:
                pass


runner = TaskRunner()