from fastapi import APIRouter, HTTPException
from app.core.database import get_connection
from pydantic import BaseModel
from typing import List
from decimal import Decimal
from datetime import date

router = APIRouter(prefix="/journal-entries", tags=["仕訳"])


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


class JournalEntryRequest(BaseModel):
    entry_date: date
    description: str
    lines: List[JournalLine]

class JournalEntryUpdateRequest(BaseModel):
    description: str
    lines: List[JournalLine]
    updated_reason: str


class JournalEntryDeleteRequest(BaseModel):
    deleted_reason: str

@router.post("", summary="仕訳登録")
def create_journal_entry(req: JournalEntryRequest):

    from app.utils.month_lock import is_month_locked

    if is_month_locked(req.entry_date):
        raise HTTPException(
            status_code=400,
            detail="该月份已锁定，不能新增仕訳"
        )

    if not req.lines:
        raise HTTPException(status_code=400, detail="仕訳明細不能为空")

    # （可选）简单的借贷平衡校验
    total_debit = sum(l.debit for l in req.lines)
    total_credit = sum(l.credit for l in req.lines)
    if total_debit != total_credit:
        raise HTTPException(status_code=400, detail="借方和贷方不平衡")

    fiscal_year = req.entry_date.year

    with get_connection() as conn:
        with conn.cursor() as cur:
            # 仕訳ヘッダ
            cur.execute("""
                INSERT INTO journal_entries (
                    journal_date,
                    description,
                    fiscal_year,
                    version,
                    is_deleted,
                    created_by
                )
                VALUES (%s, %s, %s, 1, false, %s)
                RETURNING journal_id
            """, (
                req.entry_date,
                req.description,
                fiscal_year,
                "system"   # 以后可以换成登录用户
            ))

            entry_id = cur.fetchone()["journal_id"]

            # 明細
            for line in req.lines:
                cur.execute("""
                    INSERT INTO journal_lines (
                        journal_id,
                        account_id,
                        debit,
                        credit
                    )
                    VALUES (%s, %s, %s, %s)
                """, (
                    entry_id,
                    line.account_id,
                    line.debit,
                    line.credit
                ))

        conn.commit()

    return {
        "status": "ok",
        "journal_entry_id": entry_id
    }


@router.put("/{journal_id}")
def update_journal_entry(journal_id: int, req: JournalEntryUpdateRequest):
    from app.utils.month_lock import is_month_locked

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

            # ① 取得现有仕訳
            cur.execute("""
                SELECT journal_date, is_deleted, version
                  FROM journal_entries
                 WHERE journal_id = %s
            """, (journal_id,))
            row = cur.fetchone()

            if not row:
                raise HTTPException(status_code=404, detail="仕訳が存在しません")

            if row["is_deleted"]:
                raise HTTPException(status_code=400, detail="削除済み仕訳は更新できません")

            journal_date = row["journal_date"]

            # 借贷平衡校验（update）
            total_debit = sum(l.debit for l in req.lines)
            total_credit = sum(l.credit for l in req.lines)

            if total_debit != total_credit:
                raise HTTPException(status_code=400, detail="借方和贷方不平衡")


            # ② 月次锁定检查
            if is_month_locked(journal_date):
                raise HTTPException(status_code=400, detail="该月份已锁定，不能修改仕訳")

            # ③ 更新 header
            cur.execute("""
                UPDATE journal_entries
                   SET description = %s,
                       version = version + 1,
                       updated_at = NOW(),
                       updated_reason = %s
                 WHERE journal_id = %s
            """, (
                req.description,
                req.updated_reason,
                journal_id
            ))

            # ④ 删除原有明细（物理删除，OK）
            cur.execute("""
                DELETE FROM journal_lines
                 WHERE journal_id = %s
            """, (journal_id,))

            # ⑤ 插入新明细
            for line in req.lines:
                cur.execute("""
                    INSERT INTO journal_lines (
                        journal_id,
                        account_id,
                        debit,
                        credit
                    ) VALUES (%s, %s, %s, %s)
                """, (
                    journal_id,
                    line.account_id,
                    line.debit,
                    line.credit
                ))

        conn.commit()

    return {
        "status": "ok",
        "journal_id": journal_id,
        "message": "仕訳を更新しました"
    }



@router.delete("/{journal_id}", summary="仕訳删除（软删除）")
def delete_journal_entry(journal_id: int, req: JournalEntryDeleteRequest):

    with get_connection() as conn:
        with conn.cursor() as cur:
            cur.execute("""
                UPDATE journal_entries
                   SET is_deleted = true,
                       deleted_at = NOW(),
                       deleted_reason = %s
                 WHERE journal_id = %s
                   AND is_deleted = false
                RETURNING journal_id
            """, (
                req.deleted_reason,
                journal_id
            ))

            row = cur.fetchone()
            if not row:
                raise HTTPException(
                    status_code=404,
                    detail="仕訳不存在，或已被删除"
                )

        conn.commit()

    return {
        "status": "deleted",
        "journal_entry_id": journal_id
    }