import hashlib
import json
import sqlite3
import time
from typing import Any, Optional, Set


class ToolCache:
    DETERMINISTIC_TOOLS: Set[str] = {
        "read_file",
        "list_directory",
        "get_current_directory",
        "db_get",
        "db_query",
        "index_directory",
        "http_fetch",
        "web_search",
        "web_search_news",
        "search_knowledge",
        "get_knowledge_entry",
        "get_knowledge_by_category",
        "get_knowledge_statistics",
    }

    def __init__(self, db_path: str, ttl_seconds: int = 300):
        self.db_path = db_path
        self.ttl_seconds = ttl_seconds
        self._initialize_cache()

    def _initialize_cache(self):
        conn = sqlite3.connect(self.db_path, check_same_thread=False)
        cursor = conn.cursor()
        cursor.execute(
            """
            CREATE TABLE IF NOT EXISTS tool_cache (
                cache_key TEXT PRIMARY KEY,
                tool_name TEXT NOT NULL,
                result_data TEXT NOT NULL,
                created_at INTEGER NOT NULL,
                expires_at INTEGER NOT NULL,
                hit_count INTEGER DEFAULT 0
            )
        """
        )
        cursor.execute(
            """
            CREATE INDEX IF NOT EXISTS idx_tool_expires ON tool_cache(expires_at)
        """
        )
        cursor.execute(
            """
            CREATE INDEX IF NOT EXISTS idx_tool_name ON tool_cache(tool_name)
        """
        )
        conn.commit()
        conn.close()

    def _generate_cache_key(self, tool_name: str, arguments: dict) -> str:
        cache_data = {"tool": tool_name, "args": arguments}
        serialized = json.dumps(cache_data, sort_keys=True)
        return hashlib.sha256(serialized.encode()).hexdigest()

    def is_cacheable(self, tool_name: str) -> bool:
        return tool_name in self.DETERMINISTIC_TOOLS

    def get(self, tool_name: str, arguments: dict) -> Optional[Any]:
        if not self.is_cacheable(tool_name):
            return None

        cache_key = self._generate_cache_key(tool_name, arguments)

        conn = sqlite3.connect(self.db_path, check_same_thread=False)
        cursor = conn.cursor()

        current_time = int(time.time())
        cursor.execute(
            """
            SELECT result_data, hit_count FROM tool_cache
            WHERE cache_key = ? AND expires_at > ?
        """,
            (cache_key, current_time),
        )

        row = cursor.fetchone()

        if row:
            cursor.execute(
                """
                UPDATE tool_cache SET hit_count = hit_count + 1
                WHERE cache_key = ?
            """,
                (cache_key,),
            )
            conn.commit()
            conn.close()
            return json.loads(row[0])

        conn.close()
        return None

    def set(self, tool_name: str, arguments: dict, result: Any):
        if not self.is_cacheable(tool_name):
            return

        cache_key = self._generate_cache_key(tool_name, arguments)

        current_time = int(time.time())
        expires_at = current_time + self.ttl_seconds

        conn = sqlite3.connect(self.db_path, check_same_thread=False)
        cursor = conn.cursor()

        cursor.execute(
            """
            INSERT OR REPLACE INTO tool_cache
            (cache_key, tool_name, result_data, created_at, expires_at, hit_count)
            VALUES (?, ?, ?, ?, ?, 0)
        """,
            (cache_key, tool_name, json.dumps(result), current_time, expires_at),
        )

        conn.commit()
        conn.close()

    def invalidate_tool(self, tool_name: str):
        conn = sqlite3.connect(self.db_path, check_same_thread=False)
        cursor = conn.cursor()

        cursor.execute("DELETE FROM tool_cache WHERE tool_name = ?", (tool_name,))
        deleted_count = cursor.rowcount

        conn.commit()
        conn.close()

        return deleted_count

    def clear_expired(self):
        current_time = int(time.time())

        conn = sqlite3.connect(self.db_path, check_same_thread=False)
        cursor = conn.cursor()

        cursor.execute("DELETE FROM tool_cache WHERE expires_at <= ?", (current_time,))
        deleted_count = cursor.rowcount

        conn.commit()
        conn.close()

        return deleted_count

    def clear_all(self):
        conn = sqlite3.connect(self.db_path, check_same_thread=False)
        cursor = conn.cursor()

        cursor.execute("DELETE FROM tool_cache")
        deleted_count = cursor.rowcount

        conn.commit()
        conn.close()

        return deleted_count

    def get_statistics(self) -> dict:
        conn = sqlite3.connect(self.db_path, check_same_thread=False)
        cursor = conn.cursor()

        cursor.execute("SELECT COUNT(*) FROM tool_cache")
        total_entries = cursor.fetchone()[0]

        current_time = int(time.time())
        cursor.execute("SELECT COUNT(*) FROM tool_cache WHERE expires_at > ?", (current_time,))
        valid_entries = cursor.fetchone()[0]

        cursor.execute(
            "SELECT SUM(hit_count) FROM tool_cache WHERE expires_at > ?",
            (current_time,),
        )
        total_hits = cursor.fetchone()[0] or 0

        cursor.execute(
            """
            SELECT tool_name, COUNT(*), SUM(hit_count)
            FROM tool_cache
            WHERE expires_at > ?
            GROUP BY tool_name
        """,
            (current_time,),
        )

        tool_stats = {}
        for row in cursor.fetchall():
            tool_stats[row[0]] = {"cached_entries": row[1], "total_hits": row[2] or 0}

        conn.close()

        return {
            "total_entries": total_entries,
            "valid_entries": valid_entries,
            "expired_entries": total_entries - valid_entries,
            "total_cache_hits": total_hits,
            "by_tool": tool_stats,
        }