import json
from datetime import datetime, timezone
from typing import Protocol

import httpx

from app.config import Settings
from app.models import LeaveDraftSuggestion, LeaveDraftSuggestionRequest, LeaveProgressAnswerRequest


class SuggestionGateway(Protocol):
    async def suggest(self, request: LeaveDraftSuggestionRequest) -> LeaveDraftSuggestion: ...


class ProgressGateway(Protocol):
    async def answer_progress(self, request: LeaveProgressAnswerRequest) -> str: ...


class QwenSuggestionGateway:
    def __init__(self, settings: Settings) -> None:
        self.settings = settings

    async def suggest(self, request: LeaveDraftSuggestionRequest) -> LeaveDraftSuggestion:
        if not self.settings.qwen_api_key:
            raise QwenConfigurationError("QWEN_API_KEY is not configured")
        reference_time = request.now or datetime.now(timezone.utc)
        payload = {
            "model": self.settings.qwen_model,
            "temperature": 0.1,
            "response_format": {"type": "json_object"},
            "messages": [
                {"role": "system", "content": SYSTEM_PROMPT},
                {
                    "role": "user",
                    "content": json.dumps(
                        {
                            "text": request.text,
                            "timezone": request.timezone,
                            "referenceTime": reference_time.isoformat(),
                        },
                        ensure_ascii=False,
                    ),
                },
            ],
        }
        async with httpx.AsyncClient(timeout=self.settings.request_timeout_seconds) as client:
            response = await client.post(
                f"{self.settings.qwen_base_url}/chat/completions",
                headers={"Authorization": f"Bearer {self.settings.qwen_api_key}"},
                json=payload,
            )
        if response.status_code >= 400:
            raise QwenUpstreamError(f"Qwen returned HTTP {response.status_code}")
        try:
            content = response.json()["choices"][0]["message"]["content"]
            return LeaveDraftSuggestion.model_validate_json(content)
        except (KeyError, IndexError, TypeError, ValueError) as exc:
            raise QwenUpstreamError("Qwen returned an invalid structured response") from exc

    async def answer_progress(self, request: LeaveProgressAnswerRequest) -> str:
        if not self.settings.qwen_api_key:
            raise QwenConfigurationError("QWEN_API_KEY is not configured")
        payload = {
            "model": self.settings.qwen_model,
            "temperature": 0.1,
            "response_format": {"type": "json_object"},
            "messages": [
                {"role": "system", "content": PROGRESS_SYSTEM_PROMPT},
                {"role": "user", "content": request.model_dump_json()},
            ],
        }
        async with httpx.AsyncClient(timeout=self.settings.request_timeout_seconds) as client:
            response = await client.post(f"{self.settings.qwen_base_url}/chat/completions", headers={"Authorization": f"Bearer {self.settings.qwen_api_key}"}, json=payload)
        if response.status_code >= 400:
            raise QwenUpstreamError(f"Qwen returned HTTP {response.status_code}")
        try:
            content = response.json()["choices"][0]["message"]["content"]
            answer = json.loads(content)["answer"]
            if not isinstance(answer, str) or not answer.strip() or len(answer) > 2000:
                raise ValueError("invalid answer")
            return answer.strip()
        except (KeyError, IndexError, TypeError, ValueError, json.JSONDecodeError) as exc:
            raise QwenUpstreamError("Qwen returned an invalid progress answer") from exc


SYSTEM_PROMPT = """
你是企业 OA 请假表单解析器。只把用户自然语言转换为 JSON 建议值，不执行任何业务动作。
输出必须是一个 JSON 对象，只允许字段：type、startsAt、endsAt、reason、assumptions、needsClarification。
type 只能是 PERSONAL、SICK、ANNUAL 或 null。时间必须是带时区偏移的 ISO-8601。
不能确定的值输出 null，并把需要用户补充的问题写入 needsClarification。
不得输出申请人、审批人、租户、权限、流程或隐藏字段。不得使用 Markdown。
""".strip()

PROGRESS_SYSTEM_PROMPT = """
你是企业 OA 只读流程进度助手。数据库记录已经由业务后端鉴权并选定，你只能依据输入 context 回答 question。
输出必须是 JSON 对象且只包含 answer 字段。回答必须明确当前 status；有 activeTaskNames 时说明当前节点；流程结束时说明已结束。
不得猜测审批人、原因、流程变量或预计完成时间，不得给出批准、驳回、撤回、提交等写操作指令，不得使用 Markdown。
""".strip()


class QwenConfigurationError(RuntimeError):
    pass


class QwenUpstreamError(RuntimeError):
    pass