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


class APICache:
    def __init__(self, db_path: str, ttl_seconds: int = 3600):
        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 api_cache (
                cache_key TEXT PRIMARY KEY,
                response_data TEXT NOT NULL,
                created_at INTEGER NOT NULL,
                expires_at INTEGER NOT NULL,
                model TEXT,
                token_count INTEGER
            )
        """
        )
        cursor.execute(
            """
            CREATE INDEX IF NOT EXISTS idx_expires_at ON api_cache(expires_at)
        """
        )
        conn.commit()
        conn.close()

    def _generate_cache_key(
        self, model: str, messages: list, temperature: float, max_tokens: int
    ) -> str:
        cache_data = {
            "model": model,
            "messages": messages,
            "temperature": temperature,
            "max_tokens": max_tokens,
        }
        serialized = json.dumps(cache_data, sort_keys=True)
        return hashlib.sha256(serialized.encode()).hexdigest()

    def get(
        self, model: str, messages: list, temperature: float, max_tokens: int
    ) -> Optional[Dict[str, Any]]:
        cache_key = self._generate_cache_key(model, messages, temperature, max_tokens)

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

        current_time = int(time.time())
        cursor.execute(
            """
            SELECT response_data FROM api_cache
            WHERE cache_key = ? AND expires_at > ?
        """,
            (cache_key, current_time),
        )

        row = cursor.fetchone()
        conn.close()

        if row:
            return json.loads(row[0])
        return None

    def set(
        self,
        model: str,
        messages: list,
        temperature: float,
        max_tokens: int,
        response: Dict[str, Any],
        token_count: int = 0,
    ):
        cache_key = self._generate_cache_key(model, messages, temperature, max_tokens)

        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 api_cache
            (cache_key, response_data, created_at, expires_at, model, token_count)
            VALUES (?, ?, ?, ?, ?, ?)
        """,
            (
                cache_key,
                json.dumps(response),
                current_time,
                expires_at,
                model,
                token_count,
            ),
        )

        conn.commit()
        conn.close()

    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 api_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 api_cache")
        deleted_count = cursor.rowcount

        conn.commit()
        conn.close()

        return deleted_count

    def get_statistics(self) -> Dict[str, Any]:
        conn = sqlite3.connect(self.db_path, check_same_thread=False)
        cursor = conn.cursor()

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

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

        cursor.execute(
            "SELECT SUM(token_count) FROM api_cache WHERE expires_at > ?",
            (current_time,),
        )
        total_tokens = cursor.fetchone()[0] or 0

        conn.close()

        return {
            "total_entries": total_entries,
            "valid_entries": valid_entries,
            "expired_entries": total_entries - valid_entries,
            "total_cached_tokens": total_tokens,
        }