"""Gemini model provider implementation."""

import logging
import time
from typing import Optional

from google import genai
from google.genai import types

from .base import ModelCapabilities, ModelProvider, ModelResponse, ProviderType, RangeTemperatureConstraint

logger = logging.getLogger(__name__)


class GeminiModelProvider(ModelProvider):
    """Google Gemini model provider implementation."""

    # Model configurations
    SUPPORTED_MODELS = {
        "gemini-2.5-flash-preview-05-20": {
            "context_window": 1_048_576,  # 1M tokens
            "supports_extended_thinking": True,
            "max_thinking_tokens": 24576,  # Flash 2.5 thinking budget limit
        },
        "gemini-2.5-pro-preview-06-05": {
            "context_window": 1_048_576,  # 1M tokens
            "supports_extended_thinking": True,
            "max_thinking_tokens": 32768,  # Pro 2.5 thinking budget limit
        },
        # Shorthands
        "flash": "gemini-2.5-flash-preview-05-20",
        "pro": "gemini-2.5-pro-preview-06-05",
    }

    # Thinking mode configurations - percentages of model's max_thinking_tokens
    # These percentages work across all models that support thinking
    THINKING_BUDGETS = {
        "minimal": 0.005,  # 0.5% of max - minimal thinking for fast responses
        "low": 0.08,  # 8% of max - light reasoning tasks
        "medium": 0.33,  # 33% of max - balanced reasoning (default)
        "high": 0.67,  # 67% of max - complex analysis
        "max": 1.0,  # 100% of max - full thinking budget
    }

    def __init__(self, api_key: str, **kwargs):
        """Initialize Gemini provider with API key."""
        super().__init__(api_key, **kwargs)
        self._client = None
        self._token_counters = {}  # Cache for token counting

    @property
    def client(self):
        """Lazy initialization of Gemini client."""
        if self._client is None:
            self._client = genai.Client(api_key=self.api_key)
        return self._client

    def get_capabilities(self, model_name: str) -> ModelCapabilities:
        """Get capabilities for a specific Gemini model."""
        # Resolve shorthand
        resolved_name = self._resolve_model_name(model_name)

        if resolved_name not in self.SUPPORTED_MODELS:
            raise ValueError(f"Unsupported Gemini model: {model_name}")

        # Check if model is allowed by restrictions
        from utils.model_restrictions import get_restriction_service

        restriction_service = get_restriction_service()
        if not restriction_service.is_allowed(ProviderType.GOOGLE, model_name, resolved_name):
            raise ValueError(f"Gemini model '{resolved_name}' is not allowed by restriction policy.")

        config = self.SUPPORTED_MODELS[resolved_name]

        # Gemini models support 0.0-2.0 temperature range
        temp_constraint = RangeTemperatureConstraint(0.0, 2.0, 0.7)

        return ModelCapabilities(
            provider=ProviderType.GOOGLE,
            model_name=resolved_name,
            friendly_name="Gemini",
            context_window=config["context_window"],
            supports_extended_thinking=config["supports_extended_thinking"],
            supports_system_prompts=True,
            supports_streaming=True,
            supports_function_calling=True,
            temperature_constraint=temp_constraint,
        )

    def generate_content(
        self,
        prompt: str,
        model_name: str,
        system_prompt: Optional[str] = None,
        temperature: float = 0.7,
        max_output_tokens: Optional[int] = None,
        thinking_mode: str = "medium",
        **kwargs,
    ) -> ModelResponse:
        """Generate content using Gemini model."""
        # Validate parameters
        resolved_name = self._resolve_model_name(model_name)
        self.validate_parameters(model_name, temperature)

        # Combine system prompt with user prompt if provided
        if system_prompt:
            full_prompt = f"{system_prompt}\n\n{prompt}"
        else:
            full_prompt = prompt

        # Prepare generation config
        generation_config = types.GenerateContentConfig(
            temperature=temperature,
            candidate_count=1,
        )

        # Add max output tokens if specified
        if max_output_tokens:
            generation_config.max_output_tokens = max_output_tokens

        # Add thinking configuration for models that support it
        capabilities = self.get_capabilities(model_name)
        if capabilities.supports_extended_thinking and thinking_mode in self.THINKING_BUDGETS:
            # Get model's max thinking tokens and calculate actual budget
            model_config = self.SUPPORTED_MODELS.get(resolved_name)
            if model_config and "max_thinking_tokens" in model_config:
                max_thinking_tokens = model_config["max_thinking_tokens"]
                actual_thinking_budget = int(max_thinking_tokens * self.THINKING_BUDGETS[thinking_mode])
                generation_config.thinking_config = types.ThinkingConfig(thinking_budget=actual_thinking_budget)

        # Retry logic with exponential backoff
        max_retries = 2  # Total of 2 attempts (1 initial + 1 retry)
        base_delay = 1.0  # Start with 1 second delay

        last_exception = None

        for attempt in range(max_retries):
            try:
                # Generate content
                response = self.client.models.generate_content(
                    model=resolved_name,
                    contents=full_prompt,
                    config=generation_config,
                )

                # Extract usage information if available
                usage = self._extract_usage(response)

                return ModelResponse(
                    content=response.text,
                    usage=usage,
                    model_name=resolved_name,
                    friendly_name="Gemini",
                    provider=ProviderType.GOOGLE,
                    metadata={
                        "thinking_mode": thinking_mode if capabilities.supports_extended_thinking else None,
                        "finish_reason": (
                            getattr(response.candidates[0], "finish_reason", "STOP") if response.candidates else "STOP"
                        ),
                    },
                )

            except Exception as e:
                last_exception = e

                # Check if this is a retryable error
                error_str = str(e).lower()
                is_retryable = any(
                    term in error_str
                    for term in [
                        "timeout",
                        "connection",
                        "network",
                        "temporary",
                        "unavailable",
                        "retry",
                        "429",
                        "500",
                        "502",
                        "503",
                        "504",
                    ]
                )

                # If this is the last attempt or not retryable, give up
                if attempt == max_retries - 1 or not is_retryable:
                    break

                # Calculate delay with exponential backoff
                delay = base_delay * (2**attempt)

                # Log retry attempt (could add logging here if needed)
                # For now, just sleep and retry
                time.sleep(delay)

        # If we get here, all retries failed
        error_msg = f"Gemini API error for model {resolved_name} after {max_retries} attempts: {str(last_exception)}"
        raise RuntimeError(error_msg) from last_exception

    def count_tokens(self, text: str, model_name: str) -> int:
        """Count tokens for the given text using Gemini's tokenizer."""
        self._resolve_model_name(model_name)

        # For now, use a simple estimation
        # TODO: Use actual Gemini tokenizer when available in SDK
        # Rough estimation: ~4 characters per token for English text
        return len(text) // 4

    def get_provider_type(self) -> ProviderType:
        """Get the provider type."""
        return ProviderType.GOOGLE

    def validate_model_name(self, model_name: str) -> bool:
        """Validate if the model name is supported and allowed."""
        resolved_name = self._resolve_model_name(model_name)

        # First check if model is supported
        if resolved_name not in self.SUPPORTED_MODELS or not isinstance(self.SUPPORTED_MODELS[resolved_name], dict):
            return False

        # Then check if model is allowed by restrictions
        from utils.model_restrictions import get_restriction_service

        restriction_service = get_restriction_service()
        if not restriction_service.is_allowed(ProviderType.GOOGLE, resolved_name, model_name):
            logger.debug(f"Gemini model '{model_name}' -> '{resolved_name}' blocked by restrictions")
            return False

        return True

    def supports_thinking_mode(self, model_name: str) -> bool:
        """Check if the model supports extended thinking mode."""
        capabilities = self.get_capabilities(model_name)
        return capabilities.supports_extended_thinking

    def get_thinking_budget(self, model_name: str, thinking_mode: str) -> int:
        """Get actual thinking token budget for a model and thinking mode."""
        resolved_name = self._resolve_model_name(model_name)
        model_config = self.SUPPORTED_MODELS.get(resolved_name, {})

        if not model_config.get("supports_extended_thinking", False):
            return 0

        if thinking_mode not in self.THINKING_BUDGETS:
            return 0

        max_thinking_tokens = model_config.get("max_thinking_tokens", 0)
        if max_thinking_tokens == 0:
            return 0

        return int(max_thinking_tokens * self.THINKING_BUDGETS[thinking_mode])

    def _resolve_model_name(self, model_name: str) -> str:
        """Resolve model shorthand to full name."""
        # Check if it's a shorthand
        shorthand_value = self.SUPPORTED_MODELS.get(model_name.lower())
        if isinstance(shorthand_value, str):
            return shorthand_value
        return model_name

    def _extract_usage(self, response) -> dict[str, int]:
        """Extract token usage from Gemini response."""
        usage = {}

        # Try to extract usage metadata from response
        # Note: The actual structure depends on the SDK version and response format
        if hasattr(response, "usage_metadata"):
            metadata = response.usage_metadata
            if hasattr(metadata, "prompt_token_count"):
                usage["input_tokens"] = metadata.prompt_token_count
            if hasattr(metadata, "candidates_token_count"):
                usage["output_tokens"] = metadata.candidates_token_count
            if "input_tokens" in usage and "output_tokens" in usage:
                usage["total_tokens"] = usage["input_tokens"] + usage["output_tokens"]

        return usage