app.py

"""
HuggingFace Spaces - OpenAI & Anthropic Compatible Coding API
A free, skills-only API endpoint for coding tasks (like Codex/Claude Code)
Author: Matrix Agent

Features:
- Full OpenAI API compatibility (/v1/chat/completions)
- Full Anthropic API compatibility (/v1/messages)
- Optimized for coding tasks
- Runs on free HF Spaces (2 vCPU, 16GB RAM)

API Specifications verified against:
- OpenAI: https://platform.openai.com/docs/api-reference/chat/create
- Anthropic: https://docs.anthropic.com/en/api/messages
"""

import os
import time
import uuid
import json
import asyncio
from typing import List, Optional, Union, Dict, Any, AsyncGenerator
from contextlib import asynccontextmanager

import torch
from transformers import AutoModelForCausalLM, AutoTokenizer, TextIteratorStreamer
from threading import Thread

from fastapi import FastAPI, HTTPException, Header, Request, Response
from fastapi.middleware.cors import CORSMiddleware
from fastapi.responses import StreamingResponse, JSONResponse
from pydantic import BaseModel, Field

# ============================================================================
# Configuration
# ============================================================================

MODEL_ID = os.getenv("MODEL_ID", "Qwen/Qwen2.5-Coder-1.5B-Instruct")
ANTHROPIC_VERSION = "2023-06-01"  # Standard Anthropic API version

MODEL_ALIASES = {
    # OpenAI-style model names -> actual model
    "gpt-4": MODEL_ID,
    "gpt-4-turbo": MODEL_ID,
    "gpt-4o": MODEL_ID,
    "gpt-4o-mini": MODEL_ID,
    "gpt-3.5-turbo": MODEL_ID,
    "codex": MODEL_ID,
    "code-davinci-002": MODEL_ID,
    "o1": MODEL_ID,
    "o1-mini": MODEL_ID,
    # Anthropic-style model names
    "claude-3-opus-20240229": MODEL_ID,
    "claude-3-sonnet-20240229": MODEL_ID,
    "claude-3-haiku-20240307": MODEL_ID,
    "claude-3-5-sonnet-20241022": MODEL_ID,
    "claude-3-5-haiku-20241022": MODEL_ID,
    "claude-3-opus": MODEL_ID,
    "claude-3-sonnet": MODEL_ID,
    "claude-3-haiku": MODEL_ID,
    "claude-3-5-sonnet": MODEL_ID,
    "claude-code": MODEL_ID,
}

API_KEY = os.getenv("API_KEY", "sk-free-coding-api")
MAX_TOKENS_DEFAULT = 2048
TEMPERATURE_DEFAULT = 0.7

# ============================================================================
# Global Model Instance
# ============================================================================

model = None
tokenizer = None

def load_model():
    """Load model with CPU optimization"""
    global model, tokenizer

    print(f"🚀 Loading model: {MODEL_ID}")
    print(f"📊 Device: CPU (Free HF Spaces)")

    tokenizer = AutoTokenizer.from_pretrained(
        MODEL_ID,
        trust_remote_code=True,
        padding_side="left"
    )

    if tokenizer.pad_token is None:
        tokenizer.pad_token = tokenizer.eos_token

    # Load with CPU optimizations for 16GB RAM
    model = AutoModelForCausalLM.from_pretrained(
        MODEL_ID,
        torch_dtype=torch.float32,
        device_map="cpu",
        trust_remote_code=True,
        low_cpu_mem_usage=True,
    )

    model.eval()
    print("✅ Model loaded successfully!")
    return model, tokenizer

# ============================================================================
# Pydantic Models - OpenAI Compatible (Full Spec)
# ============================================================================

class OpenAIContentPart(BaseModel):
    """Content part for multimodal messages"""
    type: str  # "text", "image_url"
    text: Optional[str] = None
    image_url: Optional[Dict[str, str]] = None

class OpenAIMessage(BaseModel):
    """OpenAI message format - supports both string and array content"""
    role: str  # "system", "user", "assistant", "tool"
    content: Optional[Union[str, List[OpenAIContentPart]]] = None
    name: Optional[str] = None
    tool_calls: Optional[List[Dict]] = None
    tool_call_id: Optional[str] = None

class OpenAIResponseFormat(BaseModel):
    """Response format specification"""
    type: str = "text"  # "text", "json_object", "json_schema"
    json_schema: Optional[Dict] = None

class OpenAIChatRequest(BaseModel):
    """Full OpenAI Chat Completions request spec"""
    model: str
    messages: List[OpenAIMessage]
    # Generation parameters
    temperature: Optional[float] = Field(default=1.0, ge=0, le=2)
    top_p: Optional[float] = Field(default=1.0, ge=0, le=1)
    n: Optional[int] = Field(default=1, ge=1, le=10)
    stream: Optional[bool] = False
    stop: Optional[Union[str, List[str]]] = None
    max_tokens: Optional[int] = None
    max_completion_tokens: Optional[int] = None  # Newer parameter
    presence_penalty: Optional[float] = Field(default=0, ge=-2, le=2)
    frequency_penalty: Optional[float] = Field(default=0, ge=-2, le=2)
    logit_bias: Optional[Dict[str, float]] = None
    logprobs: Optional[bool] = False
    top_logprobs: Optional[int] = None
    # Additional parameters
    user: Optional[str] = None
    seed: Optional[int] = None
    tools: Optional[List[Dict]] = None
    tool_choice: Optional[Union[str, Dict]] = None
    response_format: Optional[OpenAIResponseFormat] = None
    # Stream options
    stream_options: Optional[Dict] = None

class OpenAIChoiceMessage(BaseModel):
    role: str = "assistant"
    content: Optional[str] = None
    tool_calls: Optional[List[Dict]] = None

class OpenAIChoice(BaseModel):
    index: int
    message: OpenAIChoiceMessage
    finish_reason: Optional[str] = None  # "stop", "length", "tool_calls", "content_filter"
    logprobs: Optional[Dict] = None

class OpenAIStreamChoice(BaseModel):
    index: int
    delta: Dict
    finish_reason: Optional[str] = None
    logprobs: Optional[Dict] = None

class OpenAIUsage(BaseModel):
    prompt_tokens: int
    completion_tokens: int
    total_tokens: int
    prompt_tokens_details: Optional[Dict] = None
    completion_tokens_details: Optional[Dict] = None

class OpenAIChatResponse(BaseModel):
    """Full OpenAI Chat Completions response spec"""
    id: str
    object: str = "chat.completion"
    created: int
    model: str
    choices: List[OpenAIChoice]
    usage: Optional[OpenAIUsage] = None
    system_fingerprint: Optional[str] = None
    service_tier: Optional[str] = None

class OpenAIStreamResponse(BaseModel):
    id: str
    object: str = "chat.completion.chunk"
    created: int
    model: str
    choices: List[OpenAIStreamChoice]
    system_fingerprint: Optional[str] = None

class OpenAIModelInfo(BaseModel):
    id: str
    object: str = "model"
    created: int
    owned_by: str = "hf-spaces"

class OpenAIModelsResponse(BaseModel):
    object: str = "list"
    data: List[OpenAIModelInfo]

# ============================================================================
# Pydantic Models - Anthropic Compatible (Full Spec)
# ============================================================================

class AnthropicTextBlock(BaseModel):
    """Text content block"""
    type: str = "text"
    text: str

class AnthropicImageSource(BaseModel):
    """Image source for vision"""
    type: str = "base64"
    media_type: str  # "image/jpeg", "image/png", "image/webp", "image/gif"
    data: str

class AnthropicImageBlock(BaseModel):
    """Image content block"""
    type: str = "image"
    source: AnthropicImageSource

class AnthropicToolUseBlock(BaseModel):
    """Tool use content block"""
    type: str = "tool_use"
    id: str
    name: str
    input: Dict

class AnthropicToolResultBlock(BaseModel):
    """Tool result content block"""
    type: str = "tool_result"
    tool_use_id: str
    content: Union[str, List[Dict]]

# Union type for all content blocks
AnthropicContentBlock = Union[AnthropicTextBlock, AnthropicImageBlock, Dict]

class AnthropicMessage(BaseModel):
    """Anthropic message format"""
    role: str  # "user", "assistant"
    content: Union[str, List[AnthropicContentBlock]]

class AnthropicTool(BaseModel):
    """Tool definition"""
    name: str
    description: Optional[str] = None
    input_schema: Dict

class AnthropicToolChoice(BaseModel):
    """Tool choice specification"""
    type: str  # "auto", "any", "tool"
    name: Optional[str] = None

class AnthropicRequest(BaseModel):
    """Full Anthropic Messages API request spec"""
    model: str
    messages: List[AnthropicMessage]
    max_tokens: int  # Required in Anthropic API
    # Optional parameters
    system: Optional[Union[str, List[Dict]]] = None
    temperature: Optional[float] = Field(default=1.0, ge=0, le=1)
    top_p: Optional[float] = Field(default=0.999, ge=0, le=1)
    top_k: Optional[int] = None
    stream: Optional[bool] = False
    stop_sequences: Optional[List[str]] = None
    # Tool use
    tools: Optional[List[AnthropicTool]] = None
    tool_choice: Optional[AnthropicToolChoice] = None
    # Metadata
    metadata: Optional[Dict] = None

class AnthropicResponseContent(BaseModel):
    type: str = "text"
    text: Optional[str] = None
    # For tool_use
    id: Optional[str] = None
    name: Optional[str] = None
    input: Optional[Dict] = None

class AnthropicUsage(BaseModel):
    input_tokens: int
    output_tokens: int

class AnthropicResponse(BaseModel):
    """Full Anthropic Messages API response spec"""
    id: str
    type: str = "message"
    role: str = "assistant"
    model: str
    content: List[AnthropicResponseContent]
    stop_reason: Optional[str] = None  # "end_turn", "max_tokens", "stop_sequence", "tool_use"
    stop_sequence: Optional[str] = None
    usage: AnthropicUsage

# ============================================================================
# Content Parsing Utilities
# ============================================================================

def extract_text_from_openai_content(content: Union[str, List, None]) -> str:
    """Extract text from OpenAI message content (string or array)"""
    if content is None:
        return ""
    if isinstance(content, str):
        return content
    if isinstance(content, list):
        text_parts = []
        for part in content:
            if isinstance(part, dict):
                if part.get("type") == "text":
                    text_parts.append(part.get("text", ""))
            elif hasattr(part, "type") and part.type == "text":
                text_parts.append(part.text or "")
        return "\n".join(text_parts)
    return str(content)

def extract_text_from_anthropic_content(content: Union[str, List]) -> str:
    """Extract text from Anthropic message content (string or array)"""
    if isinstance(content, str):
        return content
    if isinstance(content, list):
        text_parts = []
        for block in content:
            if isinstance(block, dict):
                if block.get("type") == "text":
                    text_parts.append(block.get("text", ""))
            elif hasattr(block, "type") and block.type == "text":
                text_parts.append(block.text or "")
        return "\n".join(text_parts)
    return str(content)

def extract_system_prompt_anthropic(system: Union[str, List[Dict], None]) -> str:
    """Extract system prompt from Anthropic format"""
    if system is None:
        return ""
    if isinstance(system, str):
        return system
    if isinstance(system, list):
        # System can be array of text blocks
        text_parts = []
        for block in system:
            if isinstance(block, dict) and block.get("type") == "text":
                text_parts.append(block.get("text", ""))
        return "\n".join(text_parts)
    return ""

# ============================================================================
# Message Formatting
# ============================================================================

def format_messages_for_model(
    messages: List[Dict],
    system_prompt: Optional[str] = None
) -> str:
    """Format messages for the model using chat template"""
    formatted_messages = []

    if system_prompt:
        formatted_messages.append({"role": "system", "content": system_prompt})

    for msg in messages:
        role = msg.get("role", "user")
        content = msg.get("content", "")

        # Map tool role to assistant for compatibility
        if role == "tool":
            role = "user"

        formatted_messages.append({"role": role, "content": content})

    # Use tokenizer's chat template if available
    if hasattr(tokenizer, 'apply_chat_template') and tokenizer.chat_template:
        try:
            return tokenizer.apply_chat_template(
                formatted_messages,
                tokenize=False,
                add_generation_prompt=True
            )
        except Exception:
            pass

    # Fallback: Simple format
    prompt = ""
    for msg in formatted_messages:
        role = msg["role"]
        content = msg["content"]
        if role == "system":
            prompt += f"<|system|>\n{content}\n"
        elif role == "user":
            prompt += f"<|user|>\n{content}\n"
        elif role == "assistant":
            prompt += f"<|assistant|>\n{content}\n"
    prompt += "<|assistant|>\n"
    return prompt

# ============================================================================
# Generation Logic
# ============================================================================

def generate_response(
    prompt: str,
    max_tokens: int = MAX_TOKENS_DEFAULT,
    temperature: float = TEMPERATURE_DEFAULT,
    top_p: float = 0.95,
    top_k: Optional[int] = None,
    stop: Optional[List[str]] = None,
) -> tuple[str, int, int, str]:
    """
    Generate response from the model
    Returns: (response_text, input_tokens, output_tokens, stop_reason)
    """
    inputs = tokenizer(prompt, return_tensors="pt", truncation=True, max_length=4096)
    input_length = inputs.input_ids.shape[1]

    # Generation config
    gen_kwargs = {
        "max_new_tokens": max_tokens,
        "temperature": max(temperature, 0.01),
        "top_p": top_p,
        "do_sample": temperature > 0,
        "pad_token_id": tokenizer.pad_token_id,
        "eos_token_id": tokenizer.eos_token_id,
    }

    if top_k is not None and top_k > 0:
        gen_kwargs["top_k"] = top_k

    with torch.no_grad():
        outputs = model.generate(inputs.input_ids, **gen_kwargs)

    # Decode only the new tokens
    generated_tokens = outputs[0][input_length:]
    response_text = tokenizer.decode(generated_tokens, skip_special_tokens=True)

    output_length = len(generated_tokens)
    stop_reason = "stop"  # Default

    # Handle stop sequences
    if stop:
        for stop_seq in stop:
            if stop_seq in response_text:
                response_text = response_text.split(stop_seq)[0]
                stop_reason = "stop"
                break

    # Check if max tokens reached
    if output_length >= max_tokens:
        stop_reason = "length"

    return response_text.strip(), input_length, output_length, stop_reason

async def generate_stream(
    prompt: str,
    max_tokens: int = MAX_TOKENS_DEFAULT,
    temperature: float = TEMPERATURE_DEFAULT,
    top_p: float = 0.95,
    top_k: Optional[int] = None,
) -> AsyncGenerator[str, None]:
    """Stream generation for real-time responses"""
    inputs = tokenizer(prompt, return_tensors="pt", truncation=True, max_length=4096)

    streamer = TextIteratorStreamer(tokenizer, skip_special_tokens=True, skip_prompt=True)

    gen_kwargs = {
        "max_new_tokens": max_tokens,
        "temperature": max(temperature, 0.01),
        "top_p": top_p,
        "do_sample": temperature > 0,
        "pad_token_id": tokenizer.pad_token_id,
        "eos_token_id": tokenizer.eos_token_id,
        "streamer": streamer,
    }

    if top_k is not None and top_k > 0:
        gen_kwargs["top_k"] = top_k

    thread = Thread(target=lambda: model.generate(inputs.input_ids, **gen_kwargs))
    thread.start()

    for text in streamer:
        yield text

    thread.join()

# ============================================================================
# FastAPI Application
# ============================================================================

@asynccontextmanager
async def lifespan(app: FastAPI):
    """Load model on startup"""
    load_model()
    yield

app = FastAPI(
    title="Free Coding API",
    description="OpenAI & Anthropic compatible API for coding tasks",
    version="1.0.0",
    lifespan=lifespan
)

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

# ============================================================================
# Authentication
# ============================================================================

def verify_api_key(authorization: Optional[str] = None) -> bool:
    """Simple API key verification"""
    if not API_KEY or API_KEY == "":
        return True

    if not authorization:
        return False

    if authorization.startswith("Bearer "):
        token = authorization[7:]
    else:
        token = authorization

    return token == API_KEY

# ============================================================================
# OpenAI Compatible Endpoints
# ============================================================================

@app.get("/v1/models")
async def list_models():
    """List available models (OpenAI compatible)"""
    models = [
        OpenAIModelInfo(id=alias, created=int(time.time()))
        for alias in MODEL_ALIASES.keys()
    ]
    return OpenAIModelsResponse(data=models)

@app.get("/v1/models/{model_id}")
async def get_model(model_id: str):
    """Get model info"""
    if model_id in MODEL_ALIASES or model_id == MODEL_ID:
        return OpenAIModelInfo(id=model_id, created=int(time.time()))
    raise HTTPException(status_code=404, detail="Model not found")

@app.post("/v1/chat/completions")
async def openai_chat_completions(
    request: OpenAIChatRequest,
    authorization: Optional[str] = Header(None),
):
    """OpenAI-compatible chat completions endpoint - Full spec compliance"""

    if not verify_api_key(authorization):
        raise HTTPException(status_code=401, detail="Invalid API key")

    # Extract messages
    messages = []
    for m in request.messages:
        content = extract_text_from_openai_content(m.content)
        messages.append({"role": m.role, "content": content})

    # Extract system message if present
    system_prompt = None
    filtered_messages = []
    for msg in messages:
        if msg["role"] == "system":
            system_prompt = msg["content"]
        else:
            filtered_messages.append(msg)

    prompt = format_messages_for_model(filtered_messages, system_prompt=system_prompt)

    # Determine max tokens
    max_tokens = request.max_completion_tokens or request.max_tokens or MAX_TOKENS_DEFAULT

    # Handle stop sequences
    stop_sequences = None
    if request.stop:
        stop_sequences = [request.stop] if isinstance(request.stop, str) else request.stop

    request_id = f"chatcmpl-{uuid.uuid4().hex[:29]}"
    system_fingerprint = f"fp_{uuid.uuid4().hex[:10]}"
    created_time = int(time.time())

    if request.stream:
        # OpenAI Streaming format
        async def stream_generator():
            # First chunk with role
            first_chunk = {
                "id": request_id,
                "object": "chat.completion.chunk",
                "created": created_time,
                "model": request.model,
                "system_fingerprint": system_fingerprint,
                "choices": [{
                    "index": 0,
                    "delta": {"role": "assistant", "content": ""},
                    "logprobs": None,
                    "finish_reason": None
                }]
            }
            yield f"data: {json.dumps(first_chunk)}\n\n"

            # Stream content
            async for token in generate_stream(
                prompt,
                max_tokens=max_tokens,
                temperature=request.temperature or 1.0,
                top_p=request.top_p or 1.0,
            ):
                chunk = {
                    "id": request_id,
                    "object": "chat.completion.chunk",
                    "created": created_time,
                    "model": request.model,
                    "system_fingerprint": system_fingerprint,
                    "choices": [{
                        "index": 0,
                        "delta": {"content": token},
                        "logprobs": None,
                        "finish_reason": None
                    }]
                }
                yield f"data: {json.dumps(chunk)}\n\n"

            # Final chunk with finish_reason
            final_chunk = {
                "id": request_id,
                "object": "chat.completion.chunk",
                "created": created_time,
                "model": request.model,
                "system_fingerprint": system_fingerprint,
                "choices": [{
                    "index": 0,
                    "delta": {},
                    "logprobs": None,
                    "finish_reason": "stop"
                }]
            }
            yield f"data: {json.dumps(final_chunk)}\n\n"

            # Usage chunk if requested
            if request.stream_options and request.stream_options.get("include_usage"):
                usage_chunk = {
                    "id": request_id,
                    "object": "chat.completion.chunk",
                    "created": created_time,
                    "model": request.model,
                    "choices": [],
                    "usage": {
                        "prompt_tokens": 0,
                        "completion_tokens": 0,
                        "total_tokens": 0
                    }
                }
                yield f"data: {json.dumps(usage_chunk)}\n\n"

            yield "data: [DONE]\n\n"

        return StreamingResponse(
            stream_generator(),
            media_type="text/event-stream",
            headers={
                "Cache-Control": "no-cache",
                "Connection": "keep-alive",
                "X-Accel-Buffering": "no"
            }
        )

    # Non-streaming response
    response_text, input_tokens, output_tokens, stop_reason = generate_response(
        prompt,
        max_tokens=max_tokens,
        temperature=request.temperature or 1.0,
        top_p=request.top_p or 1.0,
        stop=stop_sequences,
    )

    # Map stop reason to OpenAI format
    openai_finish_reason = "stop" if stop_reason == "stop" else "length"

    return OpenAIChatResponse(
        id=request_id,
        created=created_time,
        model=request.model,
        system_fingerprint=system_fingerprint,
        choices=[
            OpenAIChoice(
                index=0,
                message=OpenAIChoiceMessage(role="assistant", content=response_text),
                finish_reason=openai_finish_reason,
                logprobs=None
            )
        ],
        usage=OpenAIUsage(
            prompt_tokens=input_tokens,
            completion_tokens=output_tokens,
            total_tokens=input_tokens + output_tokens
        )
    )

# ============================================================================
# Anthropic Compatible Endpoints
# ============================================================================

@app.post("/v1/messages")
async def anthropic_messages(
    request: AnthropicRequest,
    authorization: Optional[str] = Header(None),
    x_api_key: Optional[str] = Header(None, alias="x-api-key"),
    anthropic_version: Optional[str] = Header(None, alias="anthropic-version"),
):
    """Anthropic-compatible messages endpoint - Full spec compliance"""

    # Anthropic uses x-api-key header
    auth_key = x_api_key or authorization
    if not verify_api_key(auth_key):
        raise HTTPException(status_code=401, detail="Invalid API key")

    # Extract messages
    messages = []
    for m in request.messages:
        content = extract_text_from_anthropic_content(m.content)
        messages.append({"role": m.role, "content": content})

    # Extract system prompt
    system_prompt = extract_system_prompt_anthropic(request.system)

    prompt = format_messages_for_model(messages, system_prompt=system_prompt)

    request_id = f"msg_{uuid.uuid4().hex[:24]}"

    if request.stream:
        # Anthropic streaming format (Server-Sent Events)
        async def stream_generator():
            input_tokens = 0  # Would be calculated from prompt

            # 1. message_start event
            message_start = {
                "type": "message_start",
                "message": {
                    "id": request_id,
                    "type": "message",
                    "role": "assistant",
                    "model": request.model,
                    "content": [],
                    "stop_reason": None,
                    "stop_sequence": None,
                    "usage": {
                        "input_tokens": input_tokens,
                        "output_tokens": 0
                    }
                }
            }
            yield f"event: message_start\ndata: {json.dumps(message_start)}\n\n"

            # 2. content_block_start event
            content_block_start = {
                "type": "content_block_start",
                "index": 0,
                "content_block": {
                    "type": "text",
                    "text": ""
                }
            }
            yield f"event: content_block_start\ndata: {json.dumps(content_block_start)}\n\n"

            # 3. Stream content_block_delta events
            output_tokens = 0
            async for token in generate_stream(
                prompt,
                max_tokens=request.max_tokens,
                temperature=request.temperature or 1.0,
                top_p=request.top_p or 0.999,
                top_k=request.top_k,
            ):
                output_tokens += 1
                delta = {
                    "type": "content_block_delta",
                    "index": 0,
                    "delta": {
                        "type": "text_delta",
                        "text": token
                    }
                }
                yield f"event: content_block_delta\ndata: {json.dumps(delta)}\n\n"

            # 4. content_block_stop event
            content_block_stop = {
                "type": "content_block_stop",
                "index": 0
            }
            yield f"event: content_block_stop\ndata: {json.dumps(content_block_stop)}\n\n"

            # 5. message_delta event
            message_delta = {
                "type": "message_delta",
                "delta": {
                    "stop_reason": "end_turn",
                    "stop_sequence": None
                },
                "usage": {
                    "output_tokens": output_tokens
                }
            }
            yield f"event: message_delta\ndata: {json.dumps(message_delta)}\n\n"

            # 6. message_stop event
            message_stop = {"type": "message_stop"}
            yield f"event: message_stop\ndata: {json.dumps(message_stop)}\n\n"

        return StreamingResponse(
            stream_generator(),
            media_type="text/event-stream",
            headers={
                "Cache-Control": "no-cache",
                "Connection": "keep-alive",
                "X-Accel-Buffering": "no"
            }
        )

    # Non-streaming response
    response_text, input_tokens, output_tokens, stop_reason = generate_response(
        prompt,
        max_tokens=request.max_tokens,
        temperature=request.temperature or 1.0,
        top_p=request.top_p or 0.999,
        top_k=request.top_k,
        stop=request.stop_sequences,
    )

    # Map stop reason to Anthropic format
    anthropic_stop_reason = "end_turn"
    stop_sequence_used = None
    if stop_reason == "length":
        anthropic_stop_reason = "max_tokens"
    elif stop_reason == "stop" and request.stop_sequences:
        for seq in request.stop_sequences:
            if seq in response_text:
                anthropic_stop_reason = "stop_sequence"
                stop_sequence_used = seq
                break

    return AnthropicResponse(
        id=request_id,
        model=request.model,
        content=[AnthropicResponseContent(type="text", text=response_text)],
        stop_reason=anthropic_stop_reason,
        stop_sequence=stop_sequence_used,
        usage=AnthropicUsage(
            input_tokens=input_tokens,
            output_tokens=output_tokens
        )
    )

# ============================================================================
# Health & Info Endpoints
# ============================================================================

@app.get("/")
async def root():
    return {
        "name": "Free Coding API",
        "version": "1.0.0",
        "model": MODEL_ID,
        "compatibility": {
            "openai": "v1 Chat Completions API",
            "anthropic": "Messages API (2023-06-01)"
        },
        "endpoints": {
            "openai_chat": "/v1/chat/completions",
            "anthropic_messages": "/v1/messages",
            "models": "/v1/models"
        },
        "docs": "/docs"
    }

@app.get("/health")
async def health():
    return {
        "status": "healthy",
        "model_loaded": model is not None,
        "model_id": MODEL_ID
    }

# ============================================================================
# Main Entry Point
# ============================================================================

if __name__ == "__main__":
    import uvicorn
    uvicorn.run(app, host="0.0.0.0", port=7860)