import asyncio
import json
import logging
import time
from dataclasses import dataclass, field
from typing import Any, Literal, TypeVar, overload

from google import genai
from google.auth.credentials import Credentials
from google.genai import types
from google.genai.types import MediaModality
from pydantic import BaseModel

from browser_use.llm.base import BaseChatModel
from browser_use.llm.exceptions import ModelProviderError
from browser_use.llm.google.serializer import GoogleMessageSerializer
from browser_use.llm.messages import BaseMessage
from browser_use.llm.schema import SchemaOptimizer
from browser_use.llm.views import ChatInvokeCompletion, ChatInvokeUsage

T = TypeVar('T', bound=BaseModel)


VerifiedGeminiModels = Literal[
	'gemini-2.0-flash',
	'gemini-2.0-flash-exp',
	'gemini-2.0-flash-lite-preview-02-05',
	'Gemini-2.0-exp',
	'gemini-2.5-flash',
	'gemini-2.5-flash-lite',
	'gemini-flash-latest',
	'gemini-flash-lite-latest',
	'gemini-2.5-pro',
	'gemma-3-27b-it',
	'gemma-3-4b',
	'gemma-3-12b',
	'gemma-3n-e2b',
	'gemma-3n-e4b',
]


@dataclass
class ChatGoogle(BaseChatModel):
	"""
	A wrapper around Google's Gemini chat model using the genai client.

	This class accepts all genai.Client parameters while adding model,
	temperature, and config parameters for the LLM interface.

	Args:
		model: The Gemini model to use
		temperature: Temperature for response generation
		config: Additional configuration parameters to pass to generate_content
			(e.g., tools, safety_settings, etc.).
		api_key: Google API key
		vertexai: Whether to use Vertex AI
		credentials: Google credentials object
		project: Google Cloud project ID
		location: Google Cloud location
		http_options: HTTP options for the client
		include_system_in_user: If True, system messages are included in the first user message
		supports_structured_output: If True, uses native JSON mode; if False, uses prompt-based fallback
		max_retries: Number of retries for retryable errors (default: 3)
		retryable_status_codes: List of HTTP status codes to retry on (default: [403,  503])
		retry_delay: Delay in seconds between retries (default: 0.01)

	Example:
		from google.genai import types

		llm = ChatGoogle(
			model='gemini-2.0-flash-exp',
			config={
				'tools': [types.Tool(code_execution=types.ToolCodeExecution())]
			},
			max_retries=5,
			retryable_status_codes=[403, 503],
			retry_delay=0.02
		)
	"""

	# Model configuration
	model: VerifiedGeminiModels | str
	temperature: float | None = 0.5
	top_p: float | None = None
	seed: int | None = None
	thinking_budget: int | None = None  # for gemini-2.5 flash and flash-lite models, default will be set to 0
	max_output_tokens: int | None = 8096
	config: types.GenerateContentConfigDict | None = None
	include_system_in_user: bool = False
	supports_structured_output: bool = True  # New flag
	max_retries: int = 3  # Number of retries for retryable errors
	retryable_status_codes: list[int] = field(default_factory=lambda: [403, 503])  # Status codes to retry on
	retry_delay: float = 0.01  # Delay in seconds between retries

	# Client initialization parameters
	api_key: str | None = None
	vertexai: bool | None = None
	credentials: Credentials | None = None
	project: str | None = None
	location: str | None = None
	http_options: types.HttpOptions | types.HttpOptionsDict | None = None

	# Internal client cache to prevent connection issues
	_client: genai.Client | None = None

	# Static
	@property
	def provider(self) -> str:
		return 'google'

	@property
	def logger(self) -> logging.Logger:
		"""Get logger for this chat instance"""
		return logging.getLogger(f'browser_use.llm.google.{self.model}')

	def _get_client_params(self) -> dict[str, Any]:
		"""Prepare client parameters dictionary."""
		# Define base client params
		base_params = {
			'api_key': self.api_key,
			'vertexai': self.vertexai,
			'credentials': self.credentials,
			'project': self.project,
			'location': self.location,
			'http_options': self.http_options,
		}

		# Create client_params dict with non-None values
		client_params = {k: v for k, v in base_params.items() if v is not None}

		return client_params

	def get_client(self) -> genai.Client:
		"""
		Returns a genai.Client instance.

		Returns:
			genai.Client: An instance of the Google genai client.
		"""
		if self._client is not None:
			return self._client

		client_params = self._get_client_params()
		self._client = genai.Client(**client_params)
		return self._client

	@property
	def name(self) -> str:
		return str(self.model)

	def _get_stop_reason(self, response: types.GenerateContentResponse) -> str | None:
		"""Extract stop_reason from Google response."""
		if hasattr(response, 'candidates') and response.candidates:
			return str(response.candidates[0].finish_reason) if hasattr(response.candidates[0], 'finish_reason') else None
		return None

	def _get_usage(self, response: types.GenerateContentResponse) -> ChatInvokeUsage | None:
		usage: ChatInvokeUsage | None = None

		if response.usage_metadata is not None:
			image_tokens = 0
			if response.usage_metadata.prompt_tokens_details is not None:
				image_tokens = sum(
					detail.token_count or 0
					for detail in response.usage_metadata.prompt_tokens_details
					if detail.modality == MediaModality.IMAGE
				)

			usage = ChatInvokeUsage(
				prompt_tokens=response.usage_metadata.prompt_token_count or 0,
				completion_tokens=(response.usage_metadata.candidates_token_count or 0)
				+ (response.usage_metadata.thoughts_token_count or 0),
				total_tokens=response.usage_metadata.total_token_count or 0,
				prompt_cached_tokens=response.usage_metadata.cached_content_token_count,
				prompt_cache_creation_tokens=None,
				prompt_image_tokens=image_tokens,
			)

		return usage

	@overload
	async def ainvoke(self, messages: list[BaseMessage], output_format: None = None) -> ChatInvokeCompletion[str]: ...

	@overload
	async def ainvoke(self, messages: list[BaseMessage], output_format: type[T]) -> ChatInvokeCompletion[T]: ...

	async def ainvoke(
		self, messages: list[BaseMessage], output_format: type[T] | None = None
	) -> ChatInvokeCompletion[T] | ChatInvokeCompletion[str]:
		"""
		Invoke the model with the given messages.

		Args:
			messages: List of chat messages
			output_format: Optional Pydantic model class for structured output

		Returns:
			Either a string response or an instance of output_format
		"""

		# Serialize messages to Google format with the include_system_in_user flag
		contents, system_instruction = GoogleMessageSerializer.serialize_messages(
			messages, include_system_in_user=self.include_system_in_user
		)

		# Build config dictionary starting with user-provided config
		config: types.GenerateContentConfigDict = {}
		if self.config:
			config = self.config.copy()

		# Apply model-specific configuration (these can override config)
		if self.temperature is not None:
			config['temperature'] = self.temperature

		# Add system instruction if present
		if system_instruction:
			config['system_instruction'] = system_instruction

		if self.top_p is not None:
			config['top_p'] = self.top_p

		if self.seed is not None:
			config['seed'] = self.seed

		# set default for flash, flash-lite, gemini-flash-lite-latest, and gemini-flash-latest models
		if self.thinking_budget is None and ('gemini-2.5-flash' in self.model or 'gemini-flash' in self.model):
			self.thinking_budget = 0

		if self.thinking_budget is not None:
			thinking_config_dict: types.ThinkingConfigDict = {'thinking_budget': self.thinking_budget}
			config['thinking_config'] = thinking_config_dict

		if self.max_output_tokens is not None:
			config['max_output_tokens'] = self.max_output_tokens

		async def _make_api_call():
			start_time = time.time()
			self.logger.debug(f'🚀 Starting API call to {self.model}')

			try:
				if output_format is None:
					# Return string response
					self.logger.debug('📄 Requesting text response')

					response = await self.get_client().aio.models.generate_content(
						model=self.model,
						contents=contents,  # type: ignore
						config=config,
					)

					elapsed = time.time() - start_time
					self.logger.debug(f'✅ Got text response in {elapsed:.2f}s')

					# Handle case where response.text might be None
					text = response.text or ''
					if not text:
						self.logger.warning('⚠️ Empty text response received')

					usage = self._get_usage(response)

					return ChatInvokeCompletion(
						completion=text,
						usage=usage,
						stop_reason=self._get_stop_reason(response),
					)

				else:
					# Handle structured output
					if self.supports_structured_output:
						# Use native JSON mode
						self.logger.debug(f'🔧 Requesting structured output for {output_format.__name__}')
						config['response_mime_type'] = 'application/json'
						# Convert Pydantic model to Gemini-compatible schema
						optimized_schema = SchemaOptimizer.create_gemini_optimized_schema(output_format)

						gemini_schema = self._fix_gemini_schema(optimized_schema)
						config['response_schema'] = gemini_schema

						response = await self.get_client().aio.models.generate_content(
							model=self.model,
							contents=contents,
							config=config,
						)

						elapsed = time.time() - start_time
						self.logger.debug(f'✅ Got structured response in {elapsed:.2f}s')

						usage = self._get_usage(response)

						# Handle case where response.parsed might be None
						if response.parsed is None:
							self.logger.debug('📝 Parsing JSON from text response')
							# When using response_schema, Gemini returns JSON as text
							if response.text:
								try:
									# Handle JSON wrapped in markdown code blocks (common Gemini behavior)
									text = response.text.strip()
									if text.startswith('```json') and text.endswith('```'):
										text = text[7:-3].strip()
										self.logger.debug('🔧 Stripped ```json``` wrapper from response')
									elif text.startswith('```') and text.endswith('```'):
										text = text[3:-3].strip()
										self.logger.debug('🔧 Stripped ``` wrapper from response')

									# Parse the JSON text and validate with the Pydantic model
									parsed_data = json.loads(text)
									return ChatInvokeCompletion(
										completion=output_format.model_validate(parsed_data),
										usage=usage,
										stop_reason=self._get_stop_reason(response),
									)
								except (json.JSONDecodeError, ValueError) as e:
									self.logger.error(f'❌ Failed to parse JSON response: {str(e)}')
									self.logger.debug(f'Raw response text: {response.text[:200]}...')
									raise ModelProviderError(
										message=f'Failed to parse or validate response {response}: {str(e)}',
										status_code=500,
										model=self.model,
									) from e
							else:
								self.logger.error('❌ No response text received')
								raise ModelProviderError(
									message=f'No response from model {response}',
									status_code=500,
									model=self.model,
								)

						# Ensure we return the correct type
						if isinstance(response.parsed, output_format):
							return ChatInvokeCompletion(
								completion=response.parsed,
								usage=usage,
								stop_reason=self._get_stop_reason(response),
							)
						else:
							# If it's not the expected type, try to validate it
							return ChatInvokeCompletion(
								completion=output_format.model_validate(response.parsed),
								usage=usage,
								stop_reason=self._get_stop_reason(response),
							)
					else:
						# Fallback: Request JSON in the prompt for models without native JSON mode
						self.logger.debug(f'🔄 Using fallback JSON mode for {output_format.__name__}')
						# Create a copy of messages to modify
						modified_messages = [m.model_copy(deep=True) for m in messages]

						# Add JSON instruction to the last message
						if modified_messages and isinstance(modified_messages[-1].content, str):
							json_instruction = f'\n\nPlease respond with a valid JSON object that matches this schema: {SchemaOptimizer.create_optimized_json_schema(output_format)}'
							modified_messages[-1].content += json_instruction

						# Re-serialize with modified messages
						fallback_contents, fallback_system = GoogleMessageSerializer.serialize_messages(
							modified_messages, include_system_in_user=self.include_system_in_user
						)

						# Update config with fallback system instruction if present
						fallback_config = config.copy()
						if fallback_system:
							fallback_config['system_instruction'] = fallback_system

						response = await self.get_client().aio.models.generate_content(
							model=self.model,
							contents=fallback_contents,  # type: ignore
							config=fallback_config,
						)

						elapsed = time.time() - start_time
						self.logger.debug(f'✅ Got fallback response in {elapsed:.2f}s')

						usage = self._get_usage(response)

						# Try to extract JSON from the text response
						if response.text:
							try:
								# Try to find JSON in the response
								text = response.text.strip()

								# Common patterns: JSON wrapped in markdown code blocks
								if text.startswith('```json') and text.endswith('```'):
									text = text[7:-3].strip()
								elif text.startswith('```') and text.endswith('```'):
									text = text[3:-3].strip()

								# Parse and validate
								parsed_data = json.loads(text)
								return ChatInvokeCompletion(
									completion=output_format.model_validate(parsed_data),
									usage=usage,
									stop_reason=self._get_stop_reason(response),
								)
							except (json.JSONDecodeError, ValueError) as e:
								self.logger.error(f'❌ Failed to parse fallback JSON: {str(e)}')
								self.logger.debug(f'Raw response text: {response.text[:200]}...')
								raise ModelProviderError(
									message=f'Model does not support JSON mode and failed to parse JSON from text response: {str(e)}',
									status_code=500,
									model=self.model,
								) from e
						else:
							self.logger.error('❌ No response text in fallback mode')
							raise ModelProviderError(
								message='No response from model',
								status_code=500,
								model=self.model,
							)
			except Exception as e:
				elapsed = time.time() - start_time
				self.logger.error(f'💥 API call failed after {elapsed:.2f}s: {type(e).__name__}: {e}')
				# Re-raise the exception
				raise

		# Retry logic for certain errors
		assert self.max_retries >= 1, 'max_retries must be at least 1'

		for attempt in range(self.max_retries):
			try:
				return await _make_api_call()
			except ModelProviderError as e:
				# Retry if status code is in retryable list and we have attempts left
				if e.status_code in self.retryable_status_codes and attempt < self.max_retries - 1:
					self.logger.warning(f'⚠️ Got {e.status_code} error, retrying... (attempt {attempt + 1}/{self.max_retries})')
					await asyncio.sleep(self.retry_delay)
					continue
				# Otherwise raise
				raise
			except Exception as e:
				# For non-ModelProviderError, wrap and raise
				error_message = str(e)
				status_code: int | None = None

				# Try to extract status code if available
				if hasattr(e, 'response'):
					response_obj = getattr(e, 'response', None)
					if response_obj and hasattr(response_obj, 'status_code'):
						status_code = getattr(response_obj, 'status_code', None)

				# Enhanced timeout error handling
				if 'timeout' in error_message.lower() or 'cancelled' in error_message.lower():
					if isinstance(e, asyncio.CancelledError) or 'CancelledError' in str(type(e)):
						error_message = 'Gemini API request was cancelled (likely timeout). Consider: 1) Reducing input size, 2) Using a different model, 3) Checking network connectivity.'
						status_code = 504
					else:
						status_code = 408
				elif any(indicator in error_message.lower() for indicator in ['forbidden', '403']):
					status_code = 403
				elif any(
					indicator in error_message.lower()
					for indicator in ['rate limit', 'resource exhausted', 'quota exceeded', 'too many requests', '429']
				):
					status_code = 429
				elif any(
					indicator in error_message.lower()
					for indicator in ['service unavailable', 'internal server error', 'bad gateway', '503', '502', '500']
				):
					status_code = 503

				raise ModelProviderError(
					message=error_message,
					status_code=status_code or 502,
					model=self.name,
				) from e

		raise RuntimeError('Retry loop completed without return or exception')

	def _fix_gemini_schema(self, schema: dict[str, Any]) -> dict[str, Any]:
		"""
		Convert a Pydantic model to a Gemini-compatible schema.

		This function removes unsupported properties like 'additionalProperties' and resolves
		$ref references that Gemini doesn't support.
		"""

		# Handle $defs and $ref resolution
		if '$defs' in schema:
			defs = schema.pop('$defs')

			def resolve_refs(obj: Any) -> Any:
				if isinstance(obj, dict):
					if '$ref' in obj:
						ref = obj.pop('$ref')
						ref_name = ref.split('/')[-1]
						if ref_name in defs:
							# Replace the reference with the actual definition
							resolved = defs[ref_name].copy()
							# Merge any additional properties from the reference
							for key, value in obj.items():
								if key != '$ref':
									resolved[key] = value
							return resolve_refs(resolved)
						return obj
					else:
						# Recursively process all dictionary values
						return {k: resolve_refs(v) for k, v in obj.items()}
				elif isinstance(obj, list):
					return [resolve_refs(item) for item in obj]
				return obj

			schema = resolve_refs(schema)

		# Remove unsupported properties
		def clean_schema(obj: Any) -> Any:
			if isinstance(obj, dict):
				# Remove unsupported properties
				cleaned = {}
				for key, value in obj.items():
					if key not in ['additionalProperties', 'title', 'default']:
						cleaned_value = clean_schema(value)
						# Handle empty object properties - Gemini doesn't allow empty OBJECT types
						if (
							key == 'properties'
							and isinstance(cleaned_value, dict)
							and len(cleaned_value) == 0
							and isinstance(obj.get('type', ''), str)
							and obj.get('type', '').upper() == 'OBJECT'
						):
							# Convert empty object to have at least one property
							cleaned['properties'] = {'_placeholder': {'type': 'string'}}
						else:
							cleaned[key] = cleaned_value

				# If this is an object type with empty properties, add a placeholder
				if (
					isinstance(cleaned.get('type', ''), str)
					and cleaned.get('type', '').upper() == 'OBJECT'
					and 'properties' in cleaned
					and isinstance(cleaned['properties'], dict)
					and len(cleaned['properties']) == 0
				):
					cleaned['properties'] = {'_placeholder': {'type': 'string'}}

				# Also remove 'title' from the required list if it exists
				if 'required' in cleaned and isinstance(cleaned.get('required'), list):
					cleaned['required'] = [p for p in cleaned['required'] if p != 'title']

				return cleaned
			elif isinstance(obj, list):
				return [clean_schema(item) for item in obj]
			return obj

		return clean_schema(schema)
