from fastapi import FastAPI, HTTPException, Request
from fastapi.middleware.cors import CORSMiddleware
from pydantic import BaseModel, Field
from typing import List, Dict, Any, Optional, Union
import torch
import time
import logging
import asyncio
from datetime import datetime
import json
from contextlib import asynccontextmanager
import uvicorn
import psutil
import GPUtil
from ..configs.config import Config, get_balanced_config
from ..architecture.model import create_compact_model, CompactAIModel
import os

logging.basicConfig(level=logging.INFO)
logger = logging.getLogger(__name__)

# Global model instance
model: Optional[CompactAIModel] = None
tokenizer = None  # We'll use a simple tokenizer for now


@asynccontextmanager
async def lifespan(app: FastAPI):
    """Application lifespan manager."""
    global model

    # Load model on startup
    logger.info("Loading Compact AI Model...")
    try:
        model_size = os.getenv("MODEL_SIZE", "small")
        model = create_compact_model(model_size)

        # Load checkpoint if available
        checkpoint_path = os.getenv("MODEL_CHECKPOINT")
        if checkpoint_path and os.path.exists(checkpoint_path):
            checkpoint = torch.load(checkpoint_path, map_location="cpu")
            model.load_state_dict(checkpoint)
            logger.info(f"Loaded model checkpoint from {checkpoint_path}")

        model.eval()
        if torch.cuda.is_available():
            model = model.cuda()

        logger.info("Model loaded successfully!")
    except Exception as e:
        logger.error(f"Failed to load model: {e}")
        model = None

    yield

    # Cleanup on shutdown
    logger.info("Shutting down...")


app = FastAPI(
    title="Compact AI Model API",
    description="API for the compact AI model with interleaved thinking",
    version="1.0.0",
    lifespan=lifespan,
)

# Add CORS middleware
app.add_middleware(
    CORSMiddleware,
    allow_origins=["*"],
    allow_credentials=True,
    allow_methods=["*"],
    allow_headers=["*"],
)


# Pydantic models for requests/responses
class ChatMessage(BaseModel):
    role: str = Field(..., description="Role of the message (user/assistant/system)")
    content: str = Field(..., description="Content of the message")


class ChatCompletionRequest(BaseModel):
    model: str = Field(default="compact-ai-v1", description="Model name")
    messages: List[ChatMessage] = Field(..., description="List of messages")
    max_tokens: Optional[int] = Field(default=100, description="Maximum tokens to generate")
    temperature: Optional[float] = Field(default=0.7, ge=0.0, le=2.0, description="Sampling temperature")
    top_p: Optional[float] = Field(default=1.0, ge=0.0, le=1.0, description="Top-p sampling")
    reasoning_depth: Optional[Union[str, int]] = Field(default="adaptive", description="Reasoning depth")
    early_stop_threshold: Optional[float] = Field(default=0.85, description="Early stop threshold")
    thinking_visualization: Optional[bool] = Field(default=False, description="Include thinking visualization")


class CompletionRequest(BaseModel):
    model: str = Field(default="compact-ai-v1", description="Model name")
    prompt: str = Field(..., description="Input prompt")
    max_tokens: Optional[int] = Field(default=50, description="Maximum tokens to generate")
    temperature: Optional[float] = Field(default=0.8, ge=0.0, le=2.0, description="Sampling temperature")
    reasoning_tokens: Optional[int] = Field(default=100, description="Maximum reasoning tokens")


class AnthropicMessageRequest(BaseModel):
    model: str = Field(default="compact-ai-v1", description="Model name")
    messages: List[ChatMessage] = Field(..., description="List of messages")
    max_tokens: int = Field(default=1024, description="Maximum tokens to generate")
    system: Optional[str] = Field(default=None, description="System message")
    thinking_config: Optional[Dict[str, Any]] = Field(default=None, description="Thinking configuration")


class ChatCompletionChoice(BaseModel):
    index: int
    message: ChatMessage
    finish_reason: str
    thinking_trace: Optional[Dict[str, Any]] = None


class ChatCompletionResponse(BaseModel):
    id: str
    object: str = "chat.completion"
    created: int
    model: str
    choices: List[ChatCompletionChoice]
    usage: Dict[str, int]


class CompletionChoice(BaseModel):
    text: str
    index: int
    finish_reason: str
    thinking_tokens: Optional[int] = None


class CompletionResponse(BaseModel):
    id: str
    object: str = "text_completion"
    created: int
    model: str
    choices: List[CompletionChoice]
    usage: Dict[str, int]


class AnthropicMessageResponse(BaseModel):
    id: str
    type: str = "message"
    role: str = "assistant"
    content: List[Dict[str, Any]]
    model: str
    usage: Dict[str, int]


class ModelInfo(BaseModel):
    id: str
    object: str = "model"
    created: int
    owned_by: str = "compact-ai"


class ModelListResponse(BaseModel):
    object: str = "list"
    data: List[ModelInfo]


class HealthResponse(BaseModel):
    status: str
    model_loaded: bool
    gpu_available: bool
    memory_usage: Dict[str, Any]
    uptime: str


# Simple tokenizer for demonstration (replace with proper tokenizer)
class SimpleTokenizer:
    def __init__(self, vocab_size=32000):
        self.vocab_size = vocab_size
        self.pad_token_id = 0
        self.eos_token_id = 1
        self.bos_token_id = 2

    def encode(self, text: str, max_length=None, truncation=True, padding=False):
        # Very simple tokenization - split by spaces and map to IDs
        tokens = text.split()
        token_ids = [hash(word) % (self.vocab_size - 100) + 100 for word in tokens]

        if max_length and len(token_ids) > max_length:
            token_ids = token_ids[:max_length]

        if padding and max_length:
            token_ids += [self.pad_token_id] * (max_length - len(token_ids))

        return token_ids

    def decode(self, token_ids: List[int]):
        # Simple reverse mapping (not accurate for real tokenizers)
        return " ".join([f"<token_{tid}>" for tid in token_ids])


tokenizer = SimpleTokenizer()


def generate_text(
    prompt: str,
    max_tokens: int = 50,
    temperature: float = 0.8,
    reasoning_depth: Union[str, int] = "adaptive",
    early_stop_threshold: float = 0.85,
    use_thinking: bool = True,
) -> Dict[str, Any]:
    """Generate text using the model."""
    if model is None:
        raise HTTPException(status_code=503, detail="Model not loaded")

    try:
        # Tokenize input
        input_ids = tokenizer.encode(prompt, max_length=512, truncation=True)
        input_tensor = torch.tensor([input_ids], dtype=torch.long)

        if torch.cuda.is_available():
            input_tensor = input_tensor.cuda()

        # Determine reasoning depth
        if isinstance(reasoning_depth, str):
            if reasoning_depth == "adaptive":
                max_reasoning_depth = None  # Let model decide
            elif reasoning_depth == "simple":
                max_reasoning_depth = 1
            elif reasoning_depth == "complex":
                max_reasoning_depth = 4
            else:
                max_reasoning_depth = 2
        else:
            max_reasoning_depth = reasoning_depth

        with torch.no_grad():
            outputs = model(
                input_tensor,
                use_thinking=use_thinking,
                max_reasoning_depth=max_reasoning_depth,
            )

        logits = outputs["logits"][0]  # Remove batch dimension
        thinking_results = outputs["thinking_results"]
        reasoning_tokens = outputs.get("final_tokens", 0)

        # Generate tokens
        generated_tokens = []
        current_logits = logits[-1]  # Start from last token

        for _ in range(max_tokens):
            if temperature > 0:
                probs = torch.softmax(current_logits / temperature, dim=-1)
                next_token = torch.multinomial(probs, 1).item()
            else:
                next_token = current_logits.argmax().item()

            generated_tokens.append(next_token)

            if next_token == tokenizer.eos_token_id:
                break

            # Get next logits (simplified - in practice you'd run the model again)
            if len(generated_tokens) < max_tokens:
                current_logits = current_logits  # Simplified

        # Decode generated text
        generated_text = tokenizer.decode(generated_tokens)

        return {
            "generated_text": generated_text,
            "thinking_results": thinking_results,
            "reasoning_tokens": reasoning_tokens,
            "input_tokens": len(input_ids),
            "output_tokens": len(generated_tokens),
        }

    except Exception as e:
        logger.error(f"Generation error: {e}")
        raise HTTPException(status_code=500, detail=f"Generation failed: {str(e)}")


@app.post("/v1/chat/completions", response_model=ChatCompletionResponse)
async def chat_completions(request: ChatCompletionRequest):
    """OpenAI-compatible chat completions endpoint."""
    start_time = time.time()

    # Extract the last user message as prompt
    user_messages = [msg for msg in request.messages if msg.role == "user"]
    if not user_messages:
        raise HTTPException(status_code=400, detail="No user message found")

    prompt = user_messages[-1].content

    # Add system message if present
    system_messages = [msg for msg in request.messages if msg.role == "system"]
    if system_messages:
        prompt = f"System: {system_messages[0].content}\n\n{prompt}"

    # Generate response
    result = generate_text(
        prompt=prompt,
        max_tokens=request.max_tokens or 100,
        temperature=request.temperature or 0.7,
        reasoning_depth=request.reasoning_depth or "adaptive",
        early_stop_threshold=request.early_stop_threshold or 0.85,
    )

    # Prepare thinking visualization if requested
    thinking_trace = None
    if request.thinking_visualization and result["thinking_results"]:
        thinking_trace = {
            "reasoning_paths": len(result["thinking_results"]),
            "reasoning_tokens": result["reasoning_tokens"],
            "confidence_scores": [0.85, 0.78, 0.92],  # Mock data
        }

    response = ChatCompletionResponse(
        id=f"chatcmpl-{int(time.time())}",
        created=int(time.time()),
        model=request.model,
        choices=[
            ChatCompletionChoice(
                index=0,
                message=ChatMessage(role="assistant", content=result["generated_text"]),
                finish_reason="stop",
                thinking_trace=thinking_trace,
            )
        ],
        usage={
            "prompt_tokens": result["input_tokens"],
            "completion_tokens": result["output_tokens"],
            "total_tokens": result["input_tokens"] + result["output_tokens"],
            "reasoning_tokens": result["reasoning_tokens"],
        }
    )

    logger.info(f"Chat completion took {time.time() - start_time:.2f}s")
    return response


@app.post("/v1/completions", response_model=CompletionResponse)
async def completions(request: CompletionRequest):
    """OpenAI-compatible text completions endpoint."""
    start_time = time.time()

    result = generate_text(
        prompt=request.prompt,
        max_tokens=request.max_tokens or 50,
        temperature=request.temperature or 0.8,
        reasoning_depth=2,  # Default for completions
        early_stop_threshold=0.8,
    )

    response = CompletionResponse(
        id=f"cmpl-{int(time.time())}",
        created=int(time.time()),
        model=request.model,
        choices=[
            CompletionChoice(
                text=result["generated_text"],
                index=0,
                finish_reason="stop",
                thinking_tokens=result["reasoning_tokens"],
            )
        ],
        usage={
            "prompt_tokens": result["input_tokens"],
            "completion_tokens": result["output_tokens"],
            "total_tokens": result["input_tokens"] + result["output_tokens"],
        }
    )

    logger.info(f"Completion took {time.time() - start_time:.2f}s")
    return response


@app.post("/v1/messages", response_model=AnthropicMessageResponse)
async def anthropic_messages(request: AnthropicMessageRequest):
    """Anthropic-compatible messages endpoint."""
    start_time = time.time()

    # Extract messages
    messages = []
    for msg in request.messages:
        if msg.role == "user":
            messages.append(f"Human: {msg.content}")
        elif msg.role == "assistant":
            messages.append(f"Assistant: {msg.content}")

    # Add system message
    if request.system:
        messages.insert(0, f"System: {request.system}")

    prompt = "\n\n".join(messages)

    # Parse thinking config
    thinking_config = request.thinking_config or {}
    reasoning_depth = thinking_config.get("reasoning_depth", "complex")
    visualization = thinking_config.get("thinking_visualization", True)

    result = generate_text(
        prompt=prompt,
        max_tokens=request.max_tokens,
        temperature=0.7,  # Default for Anthropic
        reasoning_depth=reasoning_depth,
        early_stop_threshold=0.85,
    )

    # Prepare content with thinking if requested
    content = [{"type": "text", "text": result["generated_text"]}]

    if visualization and result["thinking_results"]:
        thinking_text = f"\n\nThinking process used {result['reasoning_tokens']} reasoning tokens across {len(result['thinking_results'])} layers."
        content.insert(0, {"type": "text", "text": thinking_text})

    response = AnthropicMessageResponse(
        id=f"msg_{int(time.time())}",
        model=request.model,
        content=content,
        usage={
            "input_tokens": result["input_tokens"],
            "output_tokens": result["output_tokens"],
            "total_tokens": result["input_tokens"] + result["output_tokens"],
        }
    )

    logger.info(f"Anthropic message took {time.time() - start_time:.2f}s")
    return response


@app.get("/v1/models", response_model=ModelListResponse)
async def list_models():
    """List available models."""
    return ModelListResponse(
        data=[
            ModelInfo(
                id="compact-ai-v1",
                created=int(time.time()),
            )
        ]
    )


@app.get("/v1/models/{model_id}")
async def get_model(model_id: str):
    """Get model information."""
    if model_id != "compact-ai-v1":
        raise HTTPException(status_code=404, detail="Model not found")

    return ModelInfo(
        id=model_id,
        created=int(time.time()),
    )


@app.get("/health", response_model=HealthResponse)
async def health_check():
    """Health check endpoint."""
    memory_info = psutil.virtual_memory()
    gpu_info = {}

    try:
        gpus = GPUtil.getGPUs()
        if gpus:
            gpu = gpus[0]
            gpu_info = {
                "gpu_name": gpu.name,
                "gpu_memory_used": gpu.memoryUsed,
                "gpu_memory_total": gpu.memoryTotal,
                "gpu_memory_free": gpu.memoryFree,
                "gpu_utilization": gpu.load * 100,
            }
    except:
        pass

    return HealthResponse(
        status="healthy" if model is not None else "unhealthy",
        model_loaded=model is not None,
        gpu_available=torch.cuda.is_available(),
        memory_usage={
            "ram_used": memory_info.used,
            "ram_total": memory_info.total,
            "ram_percent": memory_info.percent,
            **gpu_info,
        },
        uptime=str(datetime.now() - datetime.fromtimestamp(psutil.boot_time())),
    )


@app.get("/")
async def root():
    """Root endpoint."""
    return {"message": "Compact AI Model API", "version": "1.0.0"}


if __name__ == "__main__":
    import argparse

    parser = argparse.ArgumentParser(description="Run Compact AI Model API")
    parser.add_argument("--host", default="0.0.0.0", help="Host to bind to")
    parser.add_argument("--port", type=int, default=8000, help="Port to bind to")
    parser.add_argument("--workers", type=int, default=1, help="Number of workers")
    parser.add_argument("--model-size", default="small", choices=["tiny", "small", "medium"], help="Model size")
    parser.add_argument("--checkpoint", help="Path to model checkpoint")

    args = parser.parse_args()

    # Set environment variables
    os.environ["MODEL_SIZE"] = args.model_size
    if args.checkpoint:
        os.environ["MODEL_CHECKPOINT"] = args.checkpoint

    uvicorn.run(
        "main:app",
        host=args.host,
        port=args.port,
        workers=args.workers,
        reload=False,
        log_level="info",
    )