"""
FileSystem Trace Store - 文件系统存储实现

用于跨进程数据共享，数据持久化到 .trace/ 目录
"""

import json
import os
from pathlib import Path
from typing import Dict, List, Optional, Any
from datetime import datetime

from agent.execution.models import Trace, Step


class FileSystemTraceStore:
    """文件系统 Trace 存储

    目录结构：
    .trace/
    ├── trace-001/
    │   ├── meta.json           # Trace 元数据
    │   ├── steps/
    │   │   ├── step-1.json     # 每个 step 独立文件
    │   │   ├── step-2.json
    │   │   └── step-3.json
    │   └── events.jsonl        # 事件流（WebSocket 续传）
    └── trace-002/
        └── ...
    """

    def __init__(self, base_path: str = ".trace"):
        self.base_path = Path(base_path)
        self.base_path.mkdir(exist_ok=True)

    def _get_trace_dir(self, trace_id: str) -> Path:
        """获取 trace 目录"""
        return self.base_path / trace_id

    def _get_meta_file(self, trace_id: str) -> Path:
        """获取 meta.json 文件路径"""
        return self._get_trace_dir(trace_id) / "meta.json"

    def _get_steps_dir(self, trace_id: str) -> Path:
        """获取 steps 目录"""
        return self._get_trace_dir(trace_id) / "steps"

    def _get_step_file(self, trace_id: str, step_id: str) -> Path:
        """获取 step 文件路径"""
        return self._get_steps_dir(trace_id) / f"{step_id}.json"

    def _get_events_file(self, trace_id: str) -> Path:
        """获取 events.jsonl 文件路径"""
        return self._get_trace_dir(trace_id) / "events.jsonl"

    # ===== Trace 操作 =====

    async def create_trace(self, trace: Trace) -> str:
        """创建新的 Trace"""
        trace_dir = self._get_trace_dir(trace.trace_id)
        trace_dir.mkdir(exist_ok=True)

        # 创建 steps 目录
        steps_dir = self._get_steps_dir(trace.trace_id)
        steps_dir.mkdir(exist_ok=True)

        # 写入 meta.json
        meta_file = self._get_meta_file(trace.trace_id)
        meta_file.write_text(json.dumps(trace.to_dict(), indent=2, ensure_ascii=False))

        # 创建空的 events.jsonl
        events_file = self._get_events_file(trace.trace_id)
        events_file.touch()

        return trace.trace_id

    async def get_trace(self, trace_id: str) -> Optional[Trace]:
        """获取 Trace"""
        meta_file = self._get_meta_file(trace_id)
        if not meta_file.exists():
            return None

        data = json.loads(meta_file.read_text())

        # 解析 datetime 字段
        if data.get("created_at"):
            data["created_at"] = datetime.fromisoformat(data["created_at"])
        if data.get("completed_at"):
            data["completed_at"] = datetime.fromisoformat(data["completed_at"])

        return Trace(**data)

    async def update_trace(self, trace_id: str, **updates) -> None:
        """更新 Trace"""
        trace = await self.get_trace(trace_id)
        if not trace:
            return

        # 更新字段
        for key, value in updates.items():
            if hasattr(trace, key):
                setattr(trace, key, value)

        # 写回文件
        meta_file = self._get_meta_file(trace_id)
        meta_file.write_text(json.dumps(trace.to_dict(), indent=2, ensure_ascii=False))

    async def list_traces(
        self,
        mode: Optional[str] = None,
        agent_type: Optional[str] = None,
        uid: Optional[str] = None,
        status: Optional[str] = None,
        limit: int = 50
    ) -> List[Trace]:
        """列出 Traces"""
        traces = []

        # 遍历所有 trace 目录
        if not self.base_path.exists():
            return []

        for trace_dir in self.base_path.iterdir():
            if not trace_dir.is_dir():
                continue

            meta_file = trace_dir / "meta.json"
            if not meta_file.exists():
                continue

            try:
                data = json.loads(meta_file.read_text())

                # 过滤
                if mode and data.get("mode") != mode:
                    continue
                if agent_type and data.get("agent_type") != agent_type:
                    continue
                if uid and data.get("uid") != uid:
                    continue
                if status and data.get("status") != status:
                    continue

                # 解析 datetime
                if data.get("created_at"):
                    data["created_at"] = datetime.fromisoformat(data["created_at"])
                if data.get("completed_at"):
                    data["completed_at"] = datetime.fromisoformat(data["completed_at"])

                traces.append(Trace(**data))
            except Exception:
                # 跳过损坏的文件
                continue

        # 排序（最新的在前）
        traces.sort(key=lambda t: t.created_at, reverse=True)

        return traces[:limit]

    # ===== Step 操作 =====

    async def add_step(self, step: Step) -> str:
        """添加 Step"""
        trace_id = step.trace_id

        # 1. 写入 step 文件
        step_file = self._get_step_file(trace_id, step.step_id)
        step_file.write_text(json.dumps(step.to_dict(view="full"), indent=2, ensure_ascii=False))

        # 2. 更新 trace 的统计信息
        trace = await self.get_trace(trace_id)
        if trace:
            trace.total_steps += 1
            trace.last_sequence = max(trace.last_sequence, step.sequence)

            # 累加 tokens 和 cost
            if step.tokens:
                trace.total_tokens += step.tokens
            if step.cost:
                trace.total_cost += step.cost
            if step.duration_ms:
                trace.total_duration_ms += step.duration_ms

            # 写回 meta.json
            meta_file = self._get_meta_file(trace_id)
            meta_file.write_text(json.dumps(trace.to_dict(), indent=2, ensure_ascii=False))

        # 3. 更新父节点的 UI 字段
        if step.parent_id:
            parent = await self.get_step(step.parent_id)
            if parent:
                parent.has_children = True
                parent.children_count += 1

                # 写回父节点文件
                parent_file = self._get_step_file(trace_id, step.parent_id)
                parent_file.write_text(json.dumps(parent.to_dict(view="full"), indent=2, ensure_ascii=False))

        # 4. 追加 step_added 事件
        await self.append_event(trace_id, "step_added", {
            "step_id": step.step_id,
            "step_type": step.step_type,
            "parent_id": step.parent_id,
            "sequence": step.sequence,
        })

        return step.step_id

    async def get_step(self, step_id: str) -> Optional[Step]:
        """获取 Step（扫描所有 trace）"""
        for trace_dir in self.base_path.iterdir():
            if not trace_dir.is_dir():
                continue

            step_file = trace_dir / "steps" / f"{step_id}.json"
            if step_file.exists():
                try:
                    data = json.loads(step_file.read_text())

                    # 解析 datetime
                    if data.get("created_at"):
                        data["created_at"] = datetime.fromisoformat(data["created_at"])

                    return Step(**data)
                except Exception:
                    continue

        return None

    async def get_trace_steps(self, trace_id: str) -> List[Step]:
        """获取 Trace 的所有 Steps"""
        steps_dir = self._get_steps_dir(trace_id)
        if not steps_dir.exists():
            return []

        steps = []
        for step_file in steps_dir.glob("*.json"):
            try:
                data = json.loads(step_file.read_text())

                # 解析 datetime
                if data.get("created_at"):
                    data["created_at"] = datetime.fromisoformat(data["created_at"])

                steps.append(Step(**data))
            except Exception:
                # 跳过损坏的文件
                continue

        # 按 sequence 排序
        steps.sort(key=lambda s: s.sequence)
        return steps

    async def get_step_children(self, step_id: str) -> List[Step]:
        """获取 Step 的子节点"""
        # 需要扫描所有 trace 的所有 steps
        # TODO: 可以优化为维护索引文件
        children = []

        for trace_dir in self.base_path.iterdir():
            if not trace_dir.is_dir():
                continue

            steps_dir = trace_dir / "steps"
            if not steps_dir.exists():
                continue

            for step_file in steps_dir.glob("*.json"):
                try:
                    data = json.loads(step_file.read_text())
                    if data.get("parent_id") == step_id:
                        # 解析 datetime
                        if data.get("created_at"):
                            data["created_at"] = datetime.fromisoformat(data["created_at"])
                        children.append(Step(**data))
                except Exception:
                    continue

        # 按 sequence 排序
        children.sort(key=lambda s: s.sequence)
        return children

    async def update_step(self, step_id: str, **updates) -> None:
        """更新 Step 字段"""
        step = await self.get_step(step_id)
        if not step:
            return

        # 更新字段
        for key, value in updates.items():
            if hasattr(step, key):
                setattr(step, key, value)

        # 写回文件
        step_file = self._get_step_file(step.trace_id, step_id)
        step_file.write_text(json.dumps(step.to_dict(view="full"), indent=2, ensure_ascii=False))

    # ===== 事件流操作（用于 WebSocket 断线续传）=====

    async def get_events(
        self,
        trace_id: str,
        since_event_id: int = 0
    ) -> List[Dict[str, Any]]:
        """获取事件流"""
        events_file = self._get_events_file(trace_id)
        if not events_file.exists():
            return []

        events = []
        with events_file.open('r') as f:
            for line in f:
                try:
                    event = json.loads(line.strip())
                    if event.get("event_id", 0) > since_event_id:
                        events.append(event)
                except Exception:
                    continue

        return events

    async def append_event(
        self,
        trace_id: str,
        event_type: str,
        payload: Dict[str, Any]
    ) -> int:
        """追加事件，返回 event_id"""
        # 获取 trace 并递增 event_id
        trace = await self.get_trace(trace_id)
        if not trace:
            return 0

        trace.last_event_id += 1
        event_id = trace.last_event_id

        # 更新 trace 的 last_event_id
        await self.update_trace(trace_id, last_event_id=event_id)

        # 创建事件
        event = {
            "event_id": event_id,
            "event": event_type,
            "ts": datetime.now().isoformat(),
            **payload
        }

        # 追加到 events.jsonl
        events_file = self._get_events_file(trace_id)
        with events_file.open('a') as f:
            f.write(json.dumps(event, ensure_ascii=False) + '\n')

        return event_id