from __future__ import annotations

from datetime import datetime
from typing import List, Optional

from fastapi import APIRouter, HTTPException
from fastapi.responses import Response
from pydantic import BaseModel, Field

from app.db import get_pool

router = APIRouter(tags=["domain_model_prices"])


# ── Pydantic models ──────────────────────────────────────────────────────────

class DomainModelPriceIn(BaseModel):
    model_name: str
    discount: float = Field(..., gt=0, le=1, description="折扣系数，如 0.8 表示八折")
    note: Optional[str] = None


class DomainModelPriceOut(BaseModel):
    id: int
    domain: str
    model_name: str
    discount: float
    note: Optional[str]
    created_at: datetime
    updated_at: datetime


# ── Helpers ──────────────────────────────────────────────────────────────────

async def _bump_domain_version(conn, domain: str) -> None:
    await conn.execute(
        """
        INSERT INTO domain_version (domain, version, updated_at)
        VALUES ($1, 1, NOW())
        ON CONFLICT (domain) DO UPDATE
            SET version = domain_version.version + 1,
                updated_at = NOW()
        """,
        domain,
    )


# ── Routes ───────────────────────────────────────────────────────────────────

@router.get("/discounts/{domain}/model-prices", response_model=List[DomainModelPriceOut])
async def list_domain_model_prices(domain: str) -> List[DomainModelPriceOut]:
    """列出某域名下所有已配置的模型折扣。"""
    pool = get_pool()
    rows = await pool.fetch(
        "SELECT * FROM domain_model_prices WHERE domain = $1 ORDER BY model_name",
        domain,
    )
    return [DomainModelPriceOut(**dict(r)) for r in rows]


@router.put("/discounts/{domain}/model-prices/{model_name}", response_model=DomainModelPriceOut)
async def upsert_domain_model_price(
    domain: str,
    model_name: str,
    body: DomainModelPriceIn,
) -> DomainModelPriceOut:
    """新增或更新某域名下某模型的折扣系数。"""
    pool = get_pool()
    async with pool.acquire() as conn:
        async with conn.transaction():
            row = await conn.fetchrow(
                """
                INSERT INTO domain_model_prices (domain, model_name, discount, note)
                VALUES ($1, $2, $3, $4)
                ON CONFLICT (domain, model_name) DO UPDATE
                    SET discount   = EXCLUDED.discount,
                        note       = EXCLUDED.note,
                        updated_at = NOW()
                RETURNING *
                """,
                domain,
                model_name,
                body.discount,
                body.note,
            )
            await _bump_domain_version(conn, domain)
    return DomainModelPriceOut(**dict(row))


@router.delete(
    "/discounts/{domain}/model-prices/{model_name}",
    status_code=204,
    response_model=None,
)
async def delete_domain_model_price(domain: str, model_name: str) -> Response:
    """删除某域名下某模型的折扣配置。"""
    pool = get_pool()
    async with pool.acquire() as conn:
        async with conn.transaction():
            result = await conn.execute(
                "DELETE FROM domain_model_prices WHERE domain = $1 AND model_name = $2",
                domain,
                model_name,
            )
            if result == "DELETE 0":
                raise HTTPException(status_code=404, detail="配置不存在")
            await _bump_domain_version(conn, domain)
    return Response(status_code=204)


# ── Batch upsert ─────────────────────────────────────────────────────────────

class BatchItem(BaseModel):
    model_name: str
    discount: float = Field(..., gt=0, le=1)
    note: Optional[str] = None


class BatchIn(BaseModel):
    items: List[BatchItem]


@router.put("/discounts/{domain}/model-prices", response_model=List[DomainModelPriceOut])
async def batch_upsert_domain_model_prices(
    domain: str,
    body: BatchIn,
) -> List[DomainModelPriceOut]:
    """批量新增或更新某域名下多个模型的折扣系数。"""
    if not body.items:
        return []
    pool = get_pool()
    async with pool.acquire() as conn:
        async with conn.transaction():
            rows = []
            for item in body.items:
                row = await conn.fetchrow(
                    """
                    INSERT INTO domain_model_prices (domain, model_name, discount, note)
                    VALUES ($1, $2, $3, $4)
                    ON CONFLICT (domain, model_name) DO UPDATE
                        SET discount   = EXCLUDED.discount,
                            note       = EXCLUDED.note,
                            updated_at = NOW()
                    RETURNING *
                    """,
                    domain,
                    item.model_name,
                    item.discount,
                    item.note,
                )
                rows.append(DomainModelPriceOut(**dict(row)))
            await _bump_domain_version(conn, domain)
    return rows