docstrange/services/api_key_pool.py

"""
API Key Pool Manager for DocStrange.

Manages a pool of Nanonets API keys with automatic rotation on rate limit (429).
"""

import os
import json
import time
import threading
from pathlib import Path
from typing import Optional, List, Dict, Any
import logging

logger = logging.getLogger(__name__)


class KeyStatus:
    ACTIVE = "active"
    RATE_LIMITED = "rate_limited"
    EXPIRED = "expired"


class ApiKeyEntry:
    """Represents a single API key in the pool with its state."""

    def __init__(self, key: str, source: str = "manual"):
        self.key = key
        self.source = source  # "manual", "env", "config", "credentials"
        self.status = KeyStatus.ACTIVE
        self.rate_limited_at = None
        self.reset_at = None  # When the rate limit resets (epoch time)
        self.requests_made = 0
        self.last_used = None

    def mark_rate_limited(self, reset_after_seconds: int = 3600):
        """Mark this key as rate-limited."""
        self.status = KeyStatus.RATE_LIMITED
        self.rate_limited_at = time.time()
        self.reset_at = time.time() + reset_after_seconds
        logger.warning(f"API key {self.key[:8]}... rate limited, resets at {self.reset_at}")

    def is_available(self) -> bool:
        """Check if this key is available for use."""
        if self.status == KeyStatus.ACTIVE:
            return True
        if self.status == KeyStatus.RATE_LIMITED and self.reset_at:
            if time.time() >= self.reset_at:
                self.status = KeyStatus.ACTIVE
                self.rate_limited_at = None
                self.reset_at = None
                return True
        return False

    def record_use(self):
        """Record that this key was used."""
        self.requests_made += 1
        self.last_used = time.time()


class ApiKeyPool:
    """
    Manages a pool of API keys with automatic rotation.

    When a key hits rate limit (429), it's marked as unavailable and the next
    key in the pool is tried. When all keys are exhausted, signals fallback.
    """

    _instance = None
    _lock = threading.Lock()

    def __init__(self):
        self._keys: List[ApiKeyEntry] = []
        self._current_index = 0
        self._lock_pool = threading.Lock()
        self._config_path = Path.home() / ".docstrange" / "api_keys.json"
        self._load_config()

    @classmethod
    def get_instance(cls) -> "ApiKeyPool":
        """Get singleton instance."""
        if cls._instance is None:
            with cls._lock:
                if cls._instance is None:
                    cls._instance = cls()
        return cls._instance

    def _load_config(self):
        """Load API keys from config file."""
        try:
            if self._config_path.exists():
                with open(self._config_path, 'r') as f:
                    config = json.load(f)

                keys = config.get("api_keys", [])
                for key_entry in keys:
                    if isinstance(key_entry, str):
                        self.add_key(key_entry, source="config")
                    elif isinstance(key_entry, dict) and "key" in key_entry:
                        self.add_key(key_entry["key"], source=key_entry.get("source", "config"))

                logger.info(f"Loaded {len(self._keys)} API keys from config")
        except Exception as e:
            logger.warning(f"Failed to load API key config: {e}")

        # Also check environment variable for a comma-separated list of keys
        env_keys = os.environ.get('NANONETS_API_KEYS', '')
        if env_keys:
            for key in env_keys.split(','):
                key = key.strip()
                if key:
                    self.add_key(key, source="env")

    def save_config(self):
        """Save API keys to config file."""
        try:
            config_dir = self._config_path.parent
            config_dir.mkdir(exist_ok=True)

            keys_data = []
            for entry in self._keys:
                keys_data.append({
                    "key": entry.key,
                    "source": entry.source
                })

            with open(self._config_path, 'w') as f:
                json.dump({"api_keys": keys_data}, f, indent=2)

            os.chmod(self._config_path, 0o600)
            logger.info(f"Saved {len(keys_data)} API keys to config")
        except Exception as e:
            logger.error(f"Failed to save API key config: {e}")

    def add_key(self, key: str, source: str = "manual") -> bool:
        """Add an API key to the pool."""
        with self._lock_pool:
            # Check for duplicates
            for entry in self._keys:
                if entry.key == key:
                    return False

            self._keys.append(ApiKeyEntry(key, source))
            logger.info(f"Added API key from {source} to pool (total: {len(self._keys)})")
            return True

    def remove_key(self, key: str) -> bool:
        """Remove an API key from the pool."""
        with self._lock_pool:
            for i, entry in enumerate(self._keys):
                if entry.key == key:
                    self._keys.pop(i)
                    return True
            return False

    def get_next_key(self) -> Optional[str]:
        """
        Get the next available API key.

        Returns None if all keys are rate-limited.
        """
        with self._lock_pool:
            if not self._keys:
                return None

            # Try to find an available key starting from current index
            total_keys = len(self._keys)
            for i in range(total_keys):
                idx = (self._current_index + i) % total_keys
                if self._keys[idx].is_available():
                    self._current_index = idx
                    self._keys[idx].record_use()
                    return self._keys[idx].key

            return None

    def mark_key_rate_limited(self, key: str, reset_after_seconds: int = 3600):
        """Mark a specific key as rate-limited."""
        with self._lock_pool:
            for entry in self._keys:
                if entry.key == key:
                    entry.mark_rate_limited(reset_after_seconds)
                    break

    def has_available_keys(self) -> bool:
        """Check if any API keys are available."""
        with self._lock_pool:
            return any(k.is_available() for k in self._keys)

    def get_pool_stats(self) -> Dict[str, Any]:
        """Get statistics about the key pool."""
        with self._lock_pool:
            stats = {
                "total_keys": len(self._keys),
                "available": 0,
                "rate_limited": 0,
                "total_requests": 0
            }
            for key in self._keys:
                if key.is_available():
                    stats["available"] += 1
                else:
                    stats["rate_limited"] += 1
                stats["total_requests"] += key.requests_made
            return stats

    def get_all_keys(self) -> List[str]:
        """Get all API keys (masked for display)."""
        with self._lock_pool:
            return [f"{k.key[:8]}...{k.key[-4:]}" if len(k.key) > 12 else "***" for k in self._keys]


# Convenience functions
def get_pool() -> ApiKeyPool:
    """Get the API key pool singleton."""
    return ApiKeyPool.get_instance()


def add_api_key(key: str):
    """Add an API key to the pool."""
    pool = get_pool()
    pool.add_key(key)
    pool.save_config()


def remove_api_key(key: str):
    """Remove an API key from the pool."""
    pool = get_pool()
    pool.remove_key(key)
    pool.save_config()


def list_api_keys() -> List[str]:
    """List all API keys (masked)."""
    pool = get_pool()
    return pool.get_all_keys()


def get_available_key() -> Optional[str]:
    """Get the next available API key."""
    return get_pool().get_next_key()