import hashlib
import json
import logging
import time

import httpx
from sqlalchemy import select
from sqlalchemy.ext.asyncio import AsyncSession

from app.config import settings
from app.models.app_settings import AppSettings

logger = logging.getLogger("app.services.ai_advisor")

SYSTEM_PROMPT = """
Ты — эксперт по 3D-печати из инженерных пластиков по технологии FDM.
Твоя задача — рекомендовать оптимальный материал для печати на основе описания задачи клиента.

Доступные материалы:
{materials_json}

Правила:
1. Всегда рекомендуй один основной материал и 1-2 альтернативы.
2. Учитывай: температурный режим, механические нагрузки, химическое воздействие, UV, влажность.
3. Если задача не подходит для FDM-печати (слишком мелкие детали, высокая точность) — честно скажи об этом.
4. Отвечай кратко, по делу, на русском языке.
5. Если клиент не указал критичные параметры — задай уточняющие вопросы.

Формат ответа — строго JSON:
{{
  "recommended_material_id": <int>,
  "recommended_material_name": "<str>",
  "reasoning": "<обоснование на русском>",
  "alternatives": [{{"material_id": <int>, "name": "<str>", "why": "<причина>"}}],
  "questions": ["<вопрос, если нужна доп. информация>"]
}}
"""


async def _get_setting(db: AsyncSession, key: str, default: str = "") -> str:
    result = await db.execute(select(AppSettings.value).where(AppSettings.key == key))
    row = result.scalar_one_or_none()
    return row if row is not None else default


def _make_proxy_signature(salt: str) -> tuple[str, int]:
    timestamp = int(time.time())
    hash_input = f"{timestamp}{salt}".encode()
    signature = hashlib.sha256(hash_input).hexdigest()
    return signature, timestamp


async def _call_via_proxy(proxy_url: str, proxy_salt: str, messages: list[dict]) -> str:
    """Send request through AI proxy."""
    signature, timestamp = _make_proxy_signature(proxy_salt)
    headers = {
        "x-signature": signature,
        "x-timestamp": str(timestamp),
    }
    async with httpx.AsyncClient(timeout=60.0) as client:
        resp = await client.post(
            f"{proxy_url.rstrip('/')}/generate_text",
            json={"messages": messages},
            headers=headers,
        )
    if resp.status_code != 200:
        logger.error("AI proxy error %d: %s", resp.status_code, resp.text[:500])
        raise ValueError(f"AI proxy вернул ошибку: {resp.status_code}")

    data = resp.json()
    text = data.get("response", "")
    if not text:
        raise ValueError(f"AI proxy вернул пустой ответ (finish_reason={data.get('finish_reason')})")
    return text


async def _call_direct(api_key: str, system: str, user_message: str) -> str:
    """Call Qwen via OpenAI-compatible DashScope API."""
    url = f"{settings.QWEN_BASE_URL.rstrip('/')}/chat/completions"
    headers = {
        "Authorization": f"Bearer {api_key}",
        "Content-Type": "application/json",
    }
    payload = {
        "model": settings.QWEN_MODEL,
        "messages": [
            {"role": "system", "content": system},
            {"role": "user", "content": user_message},
        ],
        "temperature": 0.3,
        "max_tokens": 1024,
    }
    async with httpx.AsyncClient(timeout=60.0) as client:
        resp = await client.post(url, json=payload, headers=headers)
    if resp.status_code != 200:
        logger.error("Qwen API error %d: %s", resp.status_code, resp.text[:500])
        raise ValueError(f"Qwen API ошибка: {resp.status_code}")

    data = resp.json()
    choices = data.get("choices", [])
    if not choices:
        raise ValueError("Qwen API вернул пустой ответ")
    return choices[0].get("message", {}).get("content", "")


def _parse_json_response(text: str) -> dict:
    try:
        return json.loads(text)
    except json.JSONDecodeError:
        start = text.find("{")
        end = text.rfind("}") + 1
        if start != -1 and end > start:
            return json.loads(text[start:end])
        raise ValueError("AI вернул невалидный JSON")


async def get_material_recommendation(
    task_description: str,
    materials_data: list[dict],
    budget_preference: str = "optimal",
    file_info: dict | None = None,
    db: AsyncSession | None = None,
) -> dict:
    """Get material recommendation — via proxy or direct, based on DB settings."""
    logger.info("=== AI Advisor request ===")
    logger.info("Task: %s", task_description)

    # Read settings from DB, fallback to config
    use_proxy = True
    proxy_url = settings.AI_PROXY_URL
    proxy_salt = settings.AI_PROXY_SALT
    direct_api_key = settings.QWEN_API_KEY

    if db:
        use_proxy_str = await _get_setting(db, "ai_use_proxy", "true")
        use_proxy = use_proxy_str.lower() in ("true", "1", "yes")
        db_proxy_url = await _get_setting(db, "ai_proxy_url")
        db_proxy_salt = await _get_setting(db, "ai_proxy_salt")
        db_api_key = await _get_setting(db, "ai_direct_api_key")
        if db_proxy_url:
            proxy_url = db_proxy_url
        if db_proxy_salt:
            proxy_salt = db_proxy_salt
        if db_api_key:
            direct_api_key = db_api_key

    materials_json = json.dumps(materials_data, ensure_ascii=False, indent=2)
    system = SYSTEM_PROMPT.format(materials_json=materials_json)

    user_message = f"Описание задачи: {task_description}\nПредпочтение по бюджету: {budget_preference}"
    if file_info:
        user_message += f"\nИнформация о модели: {json.dumps(file_info, ensure_ascii=False)}"

    start_time = time.time()

    if use_proxy:
        logger.info("Mode: PROXY (%s)", proxy_url)
        if not proxy_url:
            raise ValueError("AI proxy URL не настроен")
        messages = [{"role": "user", "content": system + "\n\n" + user_message}]
        response_text = await _call_via_proxy(proxy_url, proxy_salt, messages)
    else:
        logger.info("Mode: DIRECT (Qwen API, model=%s)", settings.QWEN_MODEL)
        if not direct_api_key:
            raise ValueError("Qwen API Key не настроен (QWEN_API_KEY)")
        response_text = await _call_direct(direct_api_key, system, user_message)

    elapsed = time.time() - start_time
    logger.info("AI responded in %.2f seconds", elapsed)
    logger.debug("Raw response (%d chars): %s", len(response_text), response_text[:500])

    result = _parse_json_response(response_text)
    logger.info("Recommended: id=%s, name=%s",
                 result.get("recommended_material_id"), result.get("recommended_material_name"))
    logger.info("=== AI Advisor complete ===")
    return result