from fastapi import APIRouter, Query
from datetime import date
from typing import Optional
from app.core.database import get_connection

router = APIRouter(prefix="/trial-balance", tags=["试算表"])


@router.get("", summary="试算表（全科目）")
def get_trial_balance(
    fiscal_year: Optional[int] = Query(None, description="会计年度（可选）"),
    date_from: Optional[date] = Query(None, description="开始日期（可选）"),
    date_to: Optional[date] = Query(None, description="结束日期（可选）"),
):
    print("### trial-balance OPTIONAL PARAMS ACTIVE ###")

    with get_connection() as conn:
        # 检查 is_latest 字段是否存在（新的版本追踪系统）
        with conn.cursor() as check_cur:
            check_cur.execute("""
                SELECT COUNT(*) as cnt
                FROM information_schema.columns 
                WHERE table_name = 'journal_entries' AND column_name = 'is_latest'
            """)
            has_is_latest = check_cur.fetchone()[0] > 0

    # 构建查询语句
    if has_is_latest:
        # 新系统：只取最新版本（is_latest = true）
        sql = """
            SELECT
                a.account_id,
                a.account_code,
                a.account_name,
                a.account_type,
                COALESCE(SUM(l.debit), 0)  AS debit,
                COALESCE(SUM(l.credit), 0) AS credit
            FROM journal_lines l
            JOIN journal_entries e ON e.journal_entry_id = l.journal_entry_id
            JOIN accounts a ON a.account_id = l.account_id
            WHERE e.is_deleted = false
            AND e.is_latest = true
            AND a.account_code NOT IN ('512', '513', '516')
        """
    else:
        # 旧系统：排除已修正的记录（使用 parent_entry_id）
        sql = """
            SELECT
                a.account_id,
                a.account_code,
                a.account_name,
                a.account_type,
                COALESCE(SUM(l.debit), 0)  AS debit,
                COALESCE(SUM(l.credit), 0) AS credit
            FROM journal_lines l
            JOIN journal_entries e ON e.journal_entry_id = l.journal_entry_id
            JOIN accounts a ON a.account_id = l.account_id
            WHERE e.is_deleted = false
            AND a.account_code NOT IN ('512', '513', '516')
            AND e.journal_entry_id NOT IN (
                SELECT parent_entry_id 
                FROM journal_entries 
                WHERE parent_entry_id IS NOT NULL
            )
        """

    params = {}

    if fiscal_year is not None:
        sql += " AND e.fiscal_year = %(fiscal_year)s"
        params["fiscal_year"] = fiscal_year

    if date_from is not None:
        sql += " AND e.entry_date >= %(date_from)s"
        params["date_from"] = date_from

    if date_to is not None:
        sql += " AND e.entry_date <= %(date_to)s"
        params["date_to"] = date_to

    sql += """
        GROUP BY
            a.account_id,
            a.account_code,
            a.account_name,
            a.account_type
        ORDER BY
            CASE 
                WHEN a.account_code < '509' THEN a.account_code
                WHEN a.account_code IN ('510', '511') THEN '508.' || a.account_code
                ELSE a.account_code
            END
    """

    with get_connection() as conn, conn.cursor() as cur:
        cur.execute(sql, params)
        rows = cur.fetchall()

    return rows


@router.get("/fiscal-years", summary="仕訳データから会計年度一覧取得（5月期）")
def get_fiscal_years():
    """
    仕訳の最小・最大日付から5月期の年度リストを生成して返す。
    例: 2025-06-01〜2026-05-31 → {"label": "令和8年(2026年)5月期", "date_from": "2025-06-01", "date_to": "2026-05-31"}
    """
    REIWA_OFFSET = 2018  # 令和元年 = 2019年

    with get_connection() as conn, conn.cursor() as cur:
        cur.execute("""
            SELECT
                MIN(entry_date)::date AS min_date,
                MAX(entry_date)::date AS max_date
            FROM journal_entries
            WHERE is_deleted = false
        """)
        row = cur.fetchone()

    if not row or not row["min_date"]:
        return []

    min_date = row["min_date"]
    max_date = row["max_date"]

    # 5月期の年度を計算: 決算年（end_year）は entry_date の月が6以上なら翌年、1〜5なら当年
    def fiscal_end_year(d):
        return d.year + 1 if d.month >= 6 else d.year

    start_fy = fiscal_end_year(min_date)
    end_fy   = fiscal_end_year(max_date)

    result = []
    for fy in range(start_fy, end_fy + 1):  # 小さい順（昇順）
        reiwa = fy - REIWA_OFFSET
        if reiwa > 0:
            wareki = f"令和{reiwa}年"
        elif reiwa == 0:
            wareki = "平成31/令和元年"
        else:
            wareki = f"平成{fy - 1988}年"
        label = f"{wareki}({fy}年)5月期"
        result.append({
            "label":     label,
            "date_from": f"{fy - 1}-06-01",
            "date_to":   f"{fy}-05-31",
        })

    return result