import asyncio
import json
import time
import uuid
from typing import AsyncIterator, List, Optional

from fastapi import APIRouter, Header, Security
from fastapi.responses import JSONResponse, StreamingResponse

from app import schemas
from app.api.endpoints.openai import (
    MODEL_ID,
    _CollectingMoviePilotAgent,
    _error_response as _openai_error_response,
)
from app.api.openai_utils import build_anthropic_messages, build_prompt, build_session_id
from app.core.config import settings
from app.core.security import anthropic_api_key_header
from app.schemas.types import MessageChannel

router = APIRouter()

SESSION_PREFIX = "anthropic:"


def _anthropic_error_response(
    message: str,
    status_code: int,
    error_type: str = "invalid_request_error",
) -> JSONResponse:
    return JSONResponse(
        status_code=status_code,
        content=schemas.AnthropicErrorResponse(
            error=schemas.AnthropicErrorDetail(type=error_type, message=message)
        ).model_dump(),
    )


def _check_auth(api_key: Optional[str]) -> Optional[JSONResponse]:
    if not api_key or api_key != settings.API_TOKEN:
        return _anthropic_error_response(
            "invalid x-api-key",
            401,
            error_type="authentication_error",
        )
    return None


async def _stream_anthropic_response(
    agent: _CollectingMoviePilotAgent,
    prompt: str,
    images: List[str],
) -> AsyncIterator[str]:
    event_queue: asyncio.Queue = asyncio.Queue()
    if hasattr(agent.stream_handler, "bind_queue"):
        agent.stream_handler.bind_queue(event_queue)

    message_id = f"msg_{uuid.uuid4().hex}"

    async def _run_agent():
        try:
            await agent.process(prompt, images=images, files=None)
        except Exception as exc:
            await event_queue.put({"error": str(exc)})
        finally:
            await event_queue.put(None)

    task = asyncio.create_task(_run_agent())
    try:
        yield f"event: message_start\ndata: {json.dumps({'type': 'message_start', 'message': {'id': message_id, 'type': 'message', 'role': 'assistant', 'content': [], 'model': MODEL_ID, 'stop_reason': None, 'stop_sequence': None, 'usage': {'input_tokens': 0, 'output_tokens': 0}}}, ensure_ascii=False)}\n\n"
        yield f"event: content_block_start\ndata: {json.dumps({'type': 'content_block_start', 'index': 0, 'content_block': {'type': 'text', 'text': ''}}, ensure_ascii=False)}\n\n"
        while True:
            item = await event_queue.get()
            if item is None:
                break
            if isinstance(item, dict) and item.get("error"):
                raise RuntimeError(str(item["error"]))
            text = str(item or "")
            if not text:
                continue
            yield f"event: content_block_delta\ndata: {json.dumps({'type': 'content_block_delta', 'index': 0, 'delta': {'type': 'text_delta', 'text': text}}, ensure_ascii=False)}\n\n"
        yield f"event: content_block_stop\ndata: {json.dumps({'type': 'content_block_stop', 'index': 0}, ensure_ascii=False)}\n\n"
        yield f"event: message_delta\ndata: {json.dumps({'type': 'message_delta', 'delta': {'stop_reason': 'end_turn', 'stop_sequence': None}, 'usage': {'output_tokens': 0}}, ensure_ascii=False)}\n\n"
        yield f"event: message_stop\ndata: {json.dumps({'type': 'message_stop'}, ensure_ascii=False)}\n\n"
    finally:
        if not task.done():
            task.cancel()
            try:
                await task
            except asyncio.CancelledError:
                pass


@router.post("/messages", summary="Anthropic compatible messages", response_model=schemas.AnthropicMessagesResponse)
async def messages(
    payload: schemas.AnthropicMessagesRequest,
    x_api_key: Optional[str] = Security(anthropic_api_key_header),
    anthropic_version: Optional[str] = Header(default=None, alias="anthropic-version"),
):
    auth_error = _check_auth(x_api_key)
    if auth_error:
        return auth_error

    if not settings.AI_AGENT_ENABLE:
        return _anthropic_error_response(
            "MoviePilot AI agent is disabled.",
            503,
            error_type="api_error",
        )

    normalized_messages = build_anthropic_messages(payload.system, payload.messages)
    try:
        prompt, images = build_prompt(normalized_messages, use_server_session=False)
    except ValueError as exc:
        return _anthropic_error_response(str(exc), 400)

    session_seed = anthropic_version or "anthropic"
    session_id = build_session_id(f"{session_seed}:{uuid.uuid4().hex}", SESSION_PREFIX)
    agent = _CollectingMoviePilotAgent(
        session_id=session_id,
        user_id=session_id,
        channel=MessageChannel.Web.value,
        source="anthropic",
        username="anthropic-client",
        stream_mode=payload.stream,
    )

    if payload.stream:
        return StreamingResponse(
            _stream_anthropic_response(agent=agent, prompt=prompt, images=images),
            media_type="text/event-stream",
            headers={
                "Cache-Control": "no-cache",
                "Connection": "keep-alive",
                "X-Accel-Buffering": "no",
            },
        )

    try:
        result = await agent.process(prompt, images=images, files=None)
    except Exception as exc:
        return _anthropic_error_response(str(exc), 500, error_type="api_error")

    content = "\n\n".join(
        message.strip()
        for message in agent.collected_messages
        if message and message.strip()
    ).strip()
    if not content and result:
        content = str(result).strip()
    if not content:
        content = "未获得有效回复。"

    return schemas.AnthropicMessagesResponse(
        id=f"msg_{uuid.uuid4().hex}",
        content=[schemas.AnthropicTextBlock(text=content)],
        model=MODEL_ID,
    )