package web

import (
	"net/http"
	"net/http/httptest"
	"testing"
)

// sameOriginRequest 是 CSRF 纵深防御的核心判据。会话 cookie 已经是 SameSite=Lax，
// 这层是防「将来有人把 SameSite 放宽」以及同站不同源。
func TestSameOriginRequest(t *testing.T) {
	cases := []struct {
		name   string
		host   string
		origin string
		ref    string
		xfh    string
		want   bool
	}{
		{name: "无任何来源头（curl/脚本）", host: "site.example", want: true},
		{name: "本站 Origin", host: "site.example", origin: "http://site.example", want: true},
		{name: "本站 Origin（带端口）", host: "site.example:8080", origin: "http://site.example:8080", want: true},
		{name: "本站 Origin（https）", host: "site.example", origin: "https://site.example", want: true},
		{name: "跨站 Origin", host: "site.example", origin: "http://evil.com", want: false},
		{name: "跨站 Origin 同后缀", host: "site.example", origin: "http://site.example.evil.com", want: false},
		{name: "Origin 为 null（沙箱 iframe）", host: "site.example", origin: "null", want: false},
		{name: "Origin 不可解析", host: "site.example", origin: "://", want: false},
		{name: "跨站 Referer", host: "site.example", ref: "http://evil.com/admin", want: false},
		{name: "本站 Referer", host: "site.example", ref: "http://site.example/admin/notes", want: true},
		{name: "Origin 优先于 Referer", host: "site.example", origin: "http://evil.com", ref: "http://site.example/x", want: false},
		{name: "反代改写 Host，靠 XFH 兜底", host: "10.0.0.5:8080", origin: "https://site.example",
			xfh: "site.example", want: true},
		{name: "反代 XFH 多段取首段", host: "10.0.0.5:8080", origin: "https://site.example",
			xfh: "site.example, proxy.internal", want: true},
		{name: "反代 XFH 也不匹配", host: "10.0.0.5:8080", origin: "https://evil.com",
			xfh: "site.example", want: false},
	}
	for _, c := range cases {
		r := httptest.NewRequest("POST", "/admin/logout", nil)
		r.Host = c.host
		if c.origin != "" {
			r.Header.Set("Origin", c.origin)
		}
		if c.ref != "" {
			r.Header.Set("Referer", c.ref)
		}
		if c.xfh != "" {
			r.Header.Set("X-Forwarded-Host", c.xfh)
		}
		if got := sameOriginRequest(r); got != c.want {
			t.Errorf("%s: sameOriginRequest = %v，期望 %v", c.name, got, c.want)
		}
	}
}

// 走完整中间件链验证接线：写请求跨站被 403，读请求不受影响。
func TestHandlerRejectsCrossOriginWrite(t *testing.T) {
	f := newLoginFixture(t)
	h := f.srv.Handler()

	post := func(method, path, origin, ref string) int {
		t.Helper()
		r := httptest.NewRequest(method, path, nil)
		if origin != "" {
			r.Header.Set("Origin", origin)
		}
		if ref != "" {
			r.Header.Set("Referer", ref)
		}
		w := httptest.NewRecorder()
		h.ServeHTTP(w, r)
		return w.Code
	}

	if code := post("POST", "/admin/logout", "http://evil.com", ""); code != http.StatusForbidden {
		t.Errorf("跨站 POST 应 403，实际 %d", code)
	}
	if code := post("POST", "/admin/logout", "null", ""); code != http.StatusForbidden {
		t.Errorf("Origin: null 的 POST 应 403，实际 %d", code)
	}
	if code := post("POST", "/admin/logout", "", "http://evil.com/x"); code != http.StatusForbidden {
		t.Errorf("跨站 Referer 的 POST 应 403，实际 %d", code)
	}
	// 本站来源与「无来源头」都要放行到业务逻辑（不是 403 即可）
	for _, c := range []struct{ name, origin, ref string }{
		{"本站 Origin", "http://example.com", ""},
		{"无来源头", "", ""},
	} {
		if code := post("POST", "/admin/logout", c.origin, c.ref); code == http.StatusForbidden {
			t.Errorf("%s 的 POST 不该被拦，实际 403", c.name)
		}
	}
	// GET 是读，带跨站 Origin 也不能拦（否则外链图片/预取就废了）
	if code := post("GET", "/healthz", "http://evil.com", ""); code == http.StatusForbidden {
		t.Errorf("GET 不该被 CSRF 守卫拦，实际 403")
	}
}