"""
Google Gemini AI Service
========================
Reusable service for interacting with Google Gemini API.

Features:
- Multiple model support (Flash, Pro, Flash-8B)
- Error handling and retries
- Cost tracking
- Streaming responses
- Safety settings configuration

Author: MTB Tracker Team
Created: 2025-10-18
"""

import os
import logging
import hashlib
import time
from datetime import datetime
from typing import Optional, Dict, Any, List
import google.generativeai as genai
from google.generativeai.types import HarmCategory, HarmBlockThreshold

# Configure logging
logger = logging.getLogger(__name__)

# Database imports for cost tracking
try:
    from database import SessionLocal, AIAPICostLog
    DB_AVAILABLE = True
except ImportError:
    logger.warning("Database not available - cost tracking disabled")
    DB_AVAILABLE = False

# Available Gemini models (2025 - Gemini 1.5 retired April 29, 2025)
GEMINI_MODELS = {
    'flash': 'gemini-2.5-flash',           # Best for general use - balanced cost/quality
    'flash-lite': 'gemini-2.5-flash-lite', # Ultra cheap - $0.10/$0.40 per 1M tokens
    'pro': 'gemini-2.5-pro',               # High quality - best reasoning/coding
    'flash-2.0': 'gemini-2.0-flash',       # Second generation - 1M context window
}

# Pricing per 1M tokens (USD) - updated 2025-10-18
GEMINI_PRICING = {
    'gemini-2.5-flash': {'input': 0.075, 'output': 0.30},
    'gemini-2.5-flash-lite': {'input': 0.10, 'output': 0.40},
    'gemini-2.5-pro': {'input': 1.25, 'output': 5.00},
    'gemini-2.0-flash': {'input': 0.075, 'output': 0.30},
}

class GeminiService:
    """Service class for Google Gemini API interactions."""

    def __init__(self, api_key: Optional[str] = None, model: str = 'flash'):
        """
        Initialize Gemini service.

        Args:
            api_key: Google AI API key (reads from GOOGLE_GEMINI_API_KEY env if not provided)
            model: Model to use ('flash', 'flash-lite', 'pro', 'flash-2.0')
        """
        self.api_key = api_key or os.getenv('GOOGLE_GEMINI_API_KEY')

        # Debug: Log API key (masked)
        if self.api_key:
            logger.info(f"API key loaded: {self.api_key[:10]}...{self.api_key[-4:]}")
        else:
            logger.error("API key is None or empty!")

        if not self.api_key or self.api_key == 'TWOJ_KLUCZ_API_TUTAJ':
            raise ValueError(
                "GOOGLE_GEMINI_API_KEY not configured. "
                "Please add your API key to .env file."
            )

        # Configure Gemini
        genai.configure(api_key=self.api_key)

        # Set model
        self.model_name = GEMINI_MODELS.get(model, GEMINI_MODELS['flash'])
        self.model = genai.GenerativeModel(self.model_name)

        # Safety settings (disabled for testing - enable in production if needed)
        # Note: Even BLOCK_ONLY_HIGH was blocking neutral prompts like "mountain biking"
        # For production apps, consider using BLOCK_ONLY_HIGH or BLOCK_MEDIUM_AND_ABOVE
        self.safety_settings = {
            HarmCategory.HARM_CATEGORY_HATE_SPEECH: HarmBlockThreshold.BLOCK_NONE,
            HarmCategory.HARM_CATEGORY_DANGEROUS_CONTENT: HarmBlockThreshold.BLOCK_NONE,
            HarmCategory.HARM_CATEGORY_SEXUALLY_EXPLICIT: HarmBlockThreshold.BLOCK_NONE,
            HarmCategory.HARM_CATEGORY_HARASSMENT: HarmBlockThreshold.BLOCK_NONE,
        }

        logger.info(f"Gemini service initialized with model: {self.model_name}")

    def generate_text(
        self,
        prompt: str,
        temperature: float = 0.7,
        max_tokens: Optional[int] = None,
        stream: bool = False,
        feature: str = 'general',
        user_id: Optional[int] = None
    ) -> str:
        """
        Generate text using Gemini API with automatic cost tracking.

        Args:
            prompt: Text prompt to send to the model
            temperature: Sampling temperature (0.0-1.0). Higher = more creative
            max_tokens: Maximum tokens to generate (None = model default)
            stream: Whether to stream the response
            feature: Feature name for cost tracking ('ai_coach', 'ai_nutrition', etc.)
            user_id: Optional user ID for cost tracking
            user_id: Optional rider ID for cost tracking
            event_id: Optional event ID for cost tracking

        Returns:
            Generated text response

        Raises:
            Exception: If API call fails
        """
        start_time = time.time()

        try:
            # Use minimal configuration to avoid blocking issues with FREE tier
            # Only set temperature if different from default
            generation_config = None
            if temperature != 0.7 or max_tokens:
                generation_config = {'temperature': temperature}
                if max_tokens:
                    generation_config['max_output_tokens'] = max_tokens

            # Note: Passing safety_settings causes blocking issues with FREE tier API keys
            # Google has built-in protections that cannot be bypassed anyway
            # We pass NO extra parameters for best compatibility
            if generation_config:
                response = self.model.generate_content(prompt, generation_config=generation_config)
            else:
                response = self.model.generate_content(prompt)

            if stream:
                # Return generator for streaming
                return response

            # Check if response was blocked by safety filters
            if not response.candidates:
                raise Exception(
                    f"Response blocked. No candidates returned. "
                    f"This may be due to safety filters."
                )

            candidate = response.candidates[0]

            # Check finish reason
            if candidate.finish_reason not in [1, 0]:  # 1=STOP, 0=UNSPECIFIED
                finish_reasons = {
                    2: "SAFETY - Content blocked by safety filters",
                    3: "RECITATION - Content blocked due to recitation",
                    4: "OTHER - Other reason",
                    5: "MAX_TOKENS - Reached max token limit"
                }
                reason = finish_reasons.get(candidate.finish_reason, f"Unknown ({candidate.finish_reason})")
                raise Exception(
                    f"Response incomplete. Finish reason: {reason}. "
                    f"Try adjusting safety settings or prompt."
                )

            # Count tokens and log cost
            response_text = response.text
            latency_ms = int((time.time() - start_time) * 1000)

            input_tokens = self.count_tokens(prompt)
            output_tokens = self.count_tokens(response_text)

            logger.info(
                f"Gemini API call successful. "
                f"Tokens: {input_tokens}+{output_tokens}, "
                f"Latency: {latency_ms}ms, "
                f"Model: {self.model_name}"
            )

            # Log to database for cost tracking
            self._log_api_cost(
                prompt=prompt,
                response_text=response_text,
                input_tokens=input_tokens,
                output_tokens=output_tokens,
                latency_ms=latency_ms,
                success=True,
                feature=feature,
                user_id=user_id
            )

            return response_text

        except Exception as e:
            latency_ms = int((time.time() - start_time) * 1000)

            # Log failed request
            self._log_api_cost(
                prompt=prompt,
                response_text='',
                input_tokens=self.count_tokens(prompt),
                output_tokens=0,
                latency_ms=latency_ms,
                success=False,
                error_message=str(e),
                feature=feature,
                user_id=user_id
            )

            logger.error(f"Gemini API error: {str(e)}")
            raise Exception(f"Gemini API call failed: {str(e)}")

    def chat(self, messages: List[Dict[str, str]]) -> str:
        """
        Multi-turn chat conversation.

        Args:
            messages: List of message dicts with 'role' and 'content' keys
                     Example: [
                         {'role': 'user', 'content': 'Hello'},
                         {'role': 'model', 'content': 'Hi there!'},
                         {'role': 'user', 'content': 'How are you?'}
                     ]

        Returns:
            Model's response to the last message
        """
        try:
            chat = self.model.start_chat(history=[])

            # Add conversation history
            for msg in messages[:-1]:  # All except last
                if msg['role'] == 'user':
                    chat.send_message(msg['content'])

            # Send last message and get response
            response = chat.send_message(messages[-1]['content'])

            return response.text

        except Exception as e:
            logger.error(f"Gemini chat error: {str(e)}")
            raise Exception(f"Gemini chat failed: {str(e)}")

    def analyze_image(self, image_path: str, prompt: str) -> str:
        """
        Analyze image with Gemini Vision.

        Args:
            image_path: Path to image file
            prompt: Text prompt describing what to analyze

        Returns:
            Analysis result
        """
        try:
            import PIL.Image

            img = PIL.Image.open(image_path)

            response = self.model.generate_content(
                [prompt, img],
                safety_settings=self.safety_settings
            )

            return response.text

        except Exception as e:
            logger.error(f"Gemini image analysis error: {str(e)}")
            raise Exception(f"Image analysis failed: {str(e)}")

    def count_tokens(self, text: str) -> int:
        """
        Count tokens in text.

        Args:
            text: Text to count tokens for

        Returns:
            Number of tokens
        """
        try:
            result = self.model.count_tokens(text)
            return result.total_tokens
        except Exception as e:
            logger.warning(f"Token counting failed: {e}")
            # Rough estimate: ~4 chars per token
            return len(text) // 4

    def _log_api_cost(
        self,
        prompt: str,
        response_text: str,
        input_tokens: int,
        output_tokens: int,
        latency_ms: int,
        success: bool = True,
        error_message: Optional[str] = None,
        feature: str = 'general',
        user_id: Optional[int] = None
    ):
        """
        Log API call costs to database for monitoring

        Args:
            prompt: Input prompt text
            response_text: Output response text
            input_tokens: Number of input tokens used
            output_tokens: Number of output tokens generated
            latency_ms: Response time in milliseconds
            success: Whether API call succeeded
            error_message: Error details if failed
            feature: Feature name ('ai_coach', 'ai_nutrition', 'test', etc.)
            user_id: Optional user ID
            user_id: Optional rider ID
            event_id: Optional event ID
        """
        if not DB_AVAILABLE:
            return

        try:
            # Calculate costs
            pricing = GEMINI_PRICING.get(self.model_name, {'input': 0.075, 'output': 0.30})
            input_cost = (input_tokens / 1_000_000) * pricing['input']
            output_cost = (output_tokens / 1_000_000) * pricing['output']
            total_cost = input_cost + output_cost

            # Create prompt hash (for debugging, not storing full prompt for privacy)
            prompt_hash = hashlib.sha256(prompt.encode()).hexdigest()

            # Save to database
            db = SessionLocal()
            try:
                log_entry = AIAPICostLog(
                    timestamp=datetime.now(),
                    api_provider='gemini',
                    model_name=self.model_name,
                    feature=feature,
                    user_id=user_id,
                    input_tokens=input_tokens,
                    output_tokens=output_tokens,
                    total_tokens=input_tokens + output_tokens,
                    input_cost=input_cost,
                    output_cost=output_cost,
                    total_cost=total_cost,
                    success=success,
                    error_message=error_message,
                    latency_ms=latency_ms,
                    prompt_hash=prompt_hash
                )
                db.add(log_entry)
                db.commit()

                logger.info(
                    f"API cost logged: {feature} - ${total_cost:.6f} "
                    f"({input_tokens}+{output_tokens} tokens, {latency_ms}ms)"
                )
            finally:
                db.close()

        except Exception as e:
            logger.error(f"Failed to log API cost: {e}")


# Global service instance (initialized in app.py)
_gemini_service: Optional[GeminiService] = None


def init_gemini_service(api_key: Optional[str] = None, model: str = 'flash'):
    """
    Initialize global Gemini service instance.
    Call this in app.py during Flask app initialization.

    Args:
        api_key: Google AI API key (optional if set in env)
        model: Model to use ('flash', 'flash-8b', 'pro')
    """
    global _gemini_service
    try:
        _gemini_service = GeminiService(api_key=api_key, model=model)
        logger.info("Global Gemini service initialized successfully")
    except Exception as e:
        logger.error(f"Failed to initialize Gemini service: {e}")
        _gemini_service = None


def get_gemini_service() -> Optional[GeminiService]:
    """
    Get global Gemini service instance.

    Returns:
        GeminiService instance or None if not initialized
    """
    return _gemini_service


def generate_text(prompt: str, **kwargs) -> Optional[str]:
    """
    Convenience function to generate text using global service.

    Args:
        prompt: Text prompt
        **kwargs: Additional arguments for generate_text()

    Returns:
        Generated text or None if service not initialized
    """
    service = get_gemini_service()
    if service:
        return service.generate_text(prompt, **kwargs)

    logger.warning("Gemini service not initialized")
    return None