"""登录界面自定义背景图接口（/api/v1/config/login-background）测试。

接口公开（无凭证可访问）：
- 运行目录存在 background.jpg / background.png 时返回对应图片二进制；
- 两者同时存在时 jpg 优先；
- 均不存在时返回 404 FILE_NOT_FOUND 标准错误体。
"""

from __future__ import annotations

import pytest


# 最小合法 PNG 文件头（IHDR 数据块），仅用于让 send_file 返回二进制
_PNG_BYTES = (
    b"\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR"
    b"\x00\x00\x00\x01\x00\x00\x00\x01\x08\x06\x00\x00\x00"
)
_JPEG_BYTES = b"\xff\xd8\xff\xe0\x00\x10JFIF"


@pytest.fixture()
def background_dir(flask_app, tmp_path):
    """把背景图查找目录指到临时目录，测试后还原。"""
    original = flask_app.config.get("DMS_LOGIN_BACKGROUND_DIR")
    flask_app.config["DMS_LOGIN_BACKGROUND_DIR"] = str(tmp_path)
    yield tmp_path
    if original is None:
        flask_app.config.pop("DMS_LOGIN_BACKGROUND_DIR", None)
    else:
        flask_app.config["DMS_LOGIN_BACKGROUND_DIR"] = original


def test_login_background_returns_jpg_when_present(client, background_dir):
    (background_dir / "background.jpg").write_bytes(_JPEG_BYTES)
    response = client.get("/api/v1/config/login-background")
    assert response.status_code == 200
    assert response.mimetype == "image/jpeg"
    assert response.data == _JPEG_BYTES
    assert response.headers["X-Content-Type-Options"] == "nosniff"
    assert "max-age" in response.headers.get("Cache-Control", "")


def test_login_background_returns_png_when_only_png_present(client, background_dir):
    (background_dir / "background.png").write_bytes(_PNG_BYTES)
    response = client.get("/api/v1/config/login-background")
    assert response.status_code == 200
    assert response.mimetype == "image/png"
    assert response.data == _PNG_BYTES


def test_login_background_prefers_jpg_over_png(client, background_dir):
    (background_dir / "background.png").write_bytes(_PNG_BYTES)
    (background_dir / "background.jpg").write_bytes(_JPEG_BYTES)
    response = client.get("/api/v1/config/login-background")
    assert response.status_code == 200
    assert response.mimetype == "image/jpeg"
    assert response.data == _JPEG_BYTES


def test_login_background_returns_404_when_absent(client, background_dir):
    response = client.get("/api/v1/config/login-background")
    assert response.status_code == 404
    body = response.get_json()
    assert body["code"] == "FILE_NOT_FOUND"
    assert body["requestId"]


# ─── 主题背景图（契约1.31）：theme 查询参数优先 background-{theme}，回落通用图 ───


def test_login_background_theme_prefers_themed_jpg(client, background_dir):
    (background_dir / "background.jpg").write_bytes(_JPEG_BYTES)
    (background_dir / "background-red.png").write_bytes(_PNG_BYTES)
    response = client.get("/api/v1/config/login-background?theme=red")
    assert response.status_code == 200
    assert response.mimetype == "image/png"
    assert response.data == _PNG_BYTES


def test_login_background_theme_falls_back_to_generic(client, background_dir):
    (background_dir / "background.jpg").write_bytes(_JPEG_BYTES)
    response = client.get("/api/v1/config/login-background?theme=green")
    assert response.status_code == 200
    assert response.mimetype == "image/jpeg"
    assert response.data == _JPEG_BYTES


def test_login_background_theme_whitelist_rejects_unknown(client, background_dir):
    (background_dir / "background.jpg").write_bytes(_JPEG_BYTES)
    # 白名单外的 theme 按未提供处理，回落通用背景图
    response = client.get("/api/v1/config/login-background?theme=..%2Fetc")
    assert response.status_code == 200
    assert response.data == _JPEG_BYTES