# -*- coding: utf-8 -*-
"""杜邦区间选择器 —— 季度(YYYY-Qn)/半年(YYYY-Hn) 解析回归用例。

缺陷背景（project-20261004-ask08-dupont-quarter-half-500-fix）：
  `resolve_window()` 的季度/半年分支判据写成 `p[4] == "q" / "h"`（应为 `p[5]`），
  且排在单月分支（`p[4] == "-"`）之后 ⇒ 死代码；真实入参 `2026-q2` / `2026-h1`
  （端点内 `.lower()`）落进单月分支 → `months_between()` 的 `int(end[5:7])`
  抛 `ValueError: invalid literal for int() ... 'q2'` → HTTP 500。

本用例只测纯函数 `resolve_window`（不连库、不写盘、不碰服务），
口径与前端 `frontend/src/views/DupontAnalysis.vue::periodOptions` 对齐。
"""
import pytest

from app.utils.dupont_basis import resolve_window

YEARS = (2024, 2025, 2026)
AVAIL = [f"{y}-{m:02d}" for y in YEARS for m in range(1, 13)]


def rw(period, **kw):
    kw.setdefault("today", "2026-10")
    return resolve_window(period, None, None, AVAIL, **kw)


# ── 正例：季度 / 半年（缺陷面 18 项） ───────────────────────────────────────

@pytest.mark.parametrize("year,q,s,e", [
    (2026, 1, "2026-01", "2026-03"),
    (2026, 2, "2026-04", "2026-06"),
    (2026, 3, "2026-07", "2026-09"),
    (2026, 4, "2026-10", "2026-12"),
    (2025, 2, "2025-04", "2025-06"),
    (2024, 4, "2024-10", "2024-12"),
])
def test_quarter_parses(year, q, s, e):
    w = rw(f"{year}-Q{q}")
    assert "error" not in w
    assert w["period_key"] == "quarter"
    assert (w["period_start"], w["period_end"]) == (s, e)
    assert w["months"] == 3


@pytest.mark.parametrize("year,h,s,e", [
    (2026, 1, "2026-01", "2026-06"),
    (2026, 2, "2026-07", "2026-12"),
    (2025, 1, "2025-01", "2025-06"),
    (2024, 2, "2024-07", "2024-12"),
])
def test_half_parses(year, h, s, e):
    w = rw(f"{year}-H{h}")
    assert "error" not in w
    assert w["period_key"] == "half"
    assert (w["period_start"], w["period_end"]) == (s, e)
    assert w["months"] == 6


def test_all_18_defect_options_parse():
    """前端选择器同一区间内的 3 年 × (2 半年 + 4 季度) = 18 项全部可解析。"""
    bad = []
    for y in YEARS:
        for h in (1, 2):
            w = rw(f"{y}-H{h}")
            if w.get("period_key") != "half" or w.get("months") != 6:
                bad.append(f"{y}-H{h} -> {w}")
        for q in (1, 2, 3, 4):
            w = rw(f"{y}-Q{q}")
            if w.get("period_key") != "quarter" or w.get("months") != 3:
                bad.append(f"{y}-Q{q} -> {w}")
    assert bad == [], bad


def test_lower_and_upper_case_equivalent():
    """端点内 `.lower()` 后入参为小写；大小写必须同解且区间一致。"""
    assert rw("2026-Q2") == rw("2026-q2")
    assert rw("2026-H1") == rw("2026-h1")


# ── 反例：单月 / 全年 / YTD / TTM / 自定义 口径不得被季度半年分支改动 ──────

@pytest.mark.parametrize("month", ["2026-01", "2026-08", "2026-12"])
def test_single_month_not_swallowed_by_quarter_half(month):
    w = rw(month)
    assert "error" not in w
    assert w["period_key"] == "month", w
    assert w["period_start"] == w["period_end"] == month
    assert w["months"] == 1


def test_full_year_still_year():
    w = rw("2026")
    assert w["period_key"] == "year"
    assert (w["period_start"], w["period_end"]) == ("2026-01", "2026-12")
    assert w["months"] == 12


def test_ytd_ttm_unchanged():
    ytd = rw("ytd", anchor="2026-10")
    assert ytd["period_key"] == "ytd"
    assert (ytd["period_start"], ytd["period_end"]) == ("2026-01", "2026-10")
    assert ytd["months"] == 10

    ttm = rw("ttm", anchor="2026-10")
    assert ttm["period_key"] == "ttm"
    assert (ttm["period_start"], ttm["period_end"]) == ("2025-10", "2026-10")
    assert ttm["months"] == 13


def test_custom_unchanged():
    w = resolve_window("custom", "2026-01", "2026-06", AVAIL, today="2026-10")
    assert w["period_key"] == "custom"
    assert (w["period_start"], w["period_end"]) == ("2026-01", "2026-06")
    assert w["months"] == 6


@pytest.mark.parametrize("junk", ["2026-qx", "2026-hx", "2026-x3", "q2", "2026-1"])
def test_malformed_period_returns_error_dict_not_raise(junk):
    """无法识别的区间参数必须回落 error dict（端点转 4xx），绝不抛异常。"""
    w = rw(junk)
    assert isinstance(w, dict)
    assert w.get("error"), (junk, w)