from fastapi import APIRouter, HTTPException, Query
from pydantic import BaseModel
from typing import List
from decimal import Decimal

from app.core.database import get_connection

router = APIRouter(prefix="/opening-balances", tags=["期首残高"])


# ---------- Models ----------

class OpeningBalanceItem(BaseModel):
    account_id: int
    debit: Decimal = Decimal("0")
    credit: Decimal = Decimal("0")


class OpeningBalanceRequest(BaseModel):
    fiscal_year: int
    balances: List[OpeningBalanceItem]


# ---------- GET：期首残高取得 ----------

@router.get("", summary="期首残高取得")
def get_opening_balances(
    fiscal_year: int = Query(..., description="会計年度（例：2025）")
):
    with get_connection() as conn, conn.cursor() as cur:
        cur.execute("""
            SELECT
                a.account_id,
                a.account_code,
                a.account_name,
                a.account_type,
                COALESCE(o.opening_debit, 0)  AS opening_debit,
                COALESCE(o.opening_credit, 0) AS opening_credit
            FROM accounts a
            LEFT JOIN opening_balances o
              ON o.account_id = a.account_id
             AND o.fiscal_year = %s
            WHERE a.is_active = true
            ORDER BY a.account_code
        """, (fiscal_year,))
        return cur.fetchall()


# ---------- POST：期首残高保存 ----------

@router.post("", summary="期首残高保存")
def save_opening_balances(req: OpeningBalanceRequest):

    # 年度锁定チェック
    cur.execute("""
        SELECT is_locked
            FROM fiscal_year_locks
            WHERE fiscal_year = %s
    """, (req.fiscal_year,))

    row = cur.fetchone()
    if row and row["is_locked"]:
        raise HTTPException(
            status_code=400,
            detail="この会計年度の期首残高は既に確定されています。"
        )

    total_debit = Decimal("0")
    total_credit = Decimal("0")

    for b in req.balances:
        total_debit += b.debit
        total_credit += b.credit

    if total_debit != total_credit:
        raise HTTPException(
            status_code=400,
            detail="借方合計と貸方合計が一致していません。"
        )

    with get_connection() as conn, conn.cursor() as cur:

        # 既存データ削除（年度単位）
        cur.execute("""
            DELETE FROM opening_balances
             WHERE fiscal_year = %s
        """, (req.fiscal_year,))

        # 再登録
        for b in req.balances:
            if b.debit == 0 and b.credit == 0:
                continue

            cur.execute("""
                INSERT INTO opening_balances
                    (fiscal_year, account_id, opening_debit, opening_credit)
                VALUES
                    (%s, %s, %s, %s)
            """, (
                req.fiscal_year,
                b.account_id,
                b.debit,
                b.credit
            ))

        conn.commit()

    return {"message": "期首残高を保存しました。"}