"""
Service Layer - QueryService（查询服务）

负责所有查询逻辑，包括 FTS5 全文搜索、标签搜索、页面查询等。

参考设计文档：第 2.3 节
"""

import logging
from typing import List, Set, Optional
from ..storage import Database, WikiPage
from .cache import CacheService

logger = logging.getLogger(__name__)


class QueryService:
    """查询服务 - 负责所有查询逻辑"""

    def __init__(self, db: Database, cache: CacheService):
        self.db = db
        self.cache = cache

    async def search(self, query: str, limit: int = 10) -> List[WikiPage]:
        """FTS5 全文搜索"""
        # 1. 检查缓存
        cache_key = f"search:{query}:{limit}"
        cached = await self.cache.get(cache_key)
        if cached:
            logger.debug(f"Cache hit for search: {query}")
            return cached

        # 2. FTS5 搜索
        results = await self.db.fts_search(query, limit)

        # 3. 缓存结果
        await self.cache.set(cache_key, results, ttl=3600)

        return results

    async def search_by_tags(self, tags: List[str]) -> List[WikiPage]:
        """按标签搜索"""
        cache_key = f"tags:{','.join(tags)}"
        cached = await self.cache.get(cache_key)
        if cached:
            return cached

        results = await self.db.search_by_tags(tags)
        await self.cache.set(cache_key, results, ttl=3600)
        return results

    async def search_by_source_tool(self, tool_name: str, limit: int = 50) -> List[WikiPage]:
        """按来源工具搜索（memory_bridge 使用）"""
        cache_key = f"tool:{tool_name}:{limit}"
        cached = await self.cache.get(cache_key)
        if cached:
            return cached

        results = await self.db.search_by_source_tool(tool_name, limit)
        await self.cache.set(cache_key, results, ttl=1800)  # 30 分钟 TTL
        return results

    async def get_page(self, path: str) -> Optional[WikiPage]:
        """获取单个页面"""
        cache_key = f"page:{path}"
        cached = await self.cache.get(cache_key)
        if cached:
            return cached

        page = await self.db.get_page(path)
        if page:
            await self.cache.set(cache_key, page, ttl=3600)
        return page

    async def get_links(self, path: str) -> Set[str]:
        """获取页面的出链"""
        cache_key = f"links:{path}"
        cached = await self.cache.get(cache_key)
        if cached:
            return cached

        links = await self.db.get_links(path)
        await self.cache.set(cache_key, links, ttl=3600)
        return links

    async def get_backlinks(self, path: str) -> Set[str]:
        """获取页面的反向链接"""
        cache_key = f"backlinks:{path}"
        cached = await self.cache.get(cache_key)
        if cached:
            return cached

        backlinks = await self.db.get_backlinks(path)
        await self.cache.set(cache_key, backlinks, ttl=3600)
        return backlinks

    async def find_orphans(self) -> Set[str]:
        """查找孤立页面（无反向链接）"""
        cache_key = "orphans"
        cached = await self.cache.get(cache_key)
        if cached:
            return cached

        all_pages = await self.db.get_all_pages()
        orphans = set()
        for page in all_pages:
            backlinks = await self.db.get_backlinks(page.path)
            if not backlinks and page.path != "index.md":
                orphans.add(page.path)

        await self.cache.set(cache_key, orphans, ttl=1800)
        return orphans

    async def get_stats(self) -> dict:
        """获取索引统计信息"""
        return await self.db.get_stats()

    async def invalidate_cache(self, pattern: str = "*") -> int:
        """使缓存失效"""
        return await self.cache.invalidate(pattern)