package main

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

func formPost(body string, cookie *http.Cookie) *http.Request {
	req := httptest.NewRequest(http.MethodPost, "/login", strings.NewReader(body))
	req.Header.Set("Content-Type", "application/x-www-form-urlencoded")
	if cookie != nil {
		req.AddCookie(cookie)
	}
	return req
}

// 未帶 Session Cookie 時不會查詢資料庫,因此 handler 可以傳入 nil db。
func TestLoginPageRendersForm(t *testing.T) {
	h := loginPageHandler(nil)
	rec := httptest.NewRecorder()
	h(rec, httptest.NewRequest(http.MethodGet, "/login", nil))
	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", rec.Code)
	}
	if ct := rec.Header().Get("Content-Type"); !strings.Contains(ct, "text/html") {
		t.Fatalf("Content-Type = %q, want text/html", ct)
	}
	if csp := rec.Header().Get("Content-Security-Policy"); !strings.Contains(csp, "default-src 'none'") || !strings.Contains(csp, "style-src 'self'") {
		t.Fatalf("Content-Security-Policy = %q, 應停用外部資源載入且樣式僅允許本站", csp)
	}
	for _, want := range []string{`<form`, `name="username"`, `name="password"`, `name="csrf_token"`, `/static/css/main.css`} {
		if !strings.Contains(rec.Body.String(), want) {
			t.Fatalf("登入表單缺少 %s", want)
		}
	}
	if !strings.Contains(rec.Header().Get("Set-Cookie"), csrfCookieName) {
		t.Fatal("輸出表單時應設定 CSRF Cookie")
	}
}

// renderLoggedInPage 不查詢資料庫，可直接以虛構 Session 測試側邊導覽欄版面。
func TestRenderLoggedInPageSidebar(t *testing.T) {
	rec := httptest.NewRecorder()
	s := &Session{
		ID:        "test-session",
		User:      User{Username: "alice", Email: "alice@example.com"},
		ExpiresAt: time.Now().Add(24 * time.Hour),
	}
	renderLoggedInPage(rec, httptest.NewRequest(http.MethodGet, "/login", nil), http.StatusOK, s, "")
	if rec.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", rec.Code)
	}
	body := rec.Body.String()
	for _, want := range []string{
		"<aside", // 側邊導覽欄
		`aria-label="側邊導覽列"`,
		"alterminal",    // 品牌區
		`href="/"`, // 導覽項目（帳號首頁）
		`aria-current="page"`,
		"帳號資訊",
		`id="sidebar-toggle"`, // 手機版純 CSS 開合（CSP 不允許 JS）
		`action="/logout"`,    // 側欄頁尾的登出表單
		`name="csrf_token"`,
		"alice@example.com",
	} {
		if !strings.Contains(body, want) {
			t.Errorf("已登入頁缺少 %s", want)
		}
	}
}

func TestRenderLoginPageStaysStandalone(t *testing.T) {
	rec := httptest.NewRecorder()
	renderLoginPage(rec, httptest.NewRequest(http.MethodGet, "/login", nil), http.StatusOK, "", "")
	if strings.Contains(rec.Body.String(), "<aside") {
		t.Fatal("登入表單頁應維持獨立版面，不含側邊導覽欄")
	}
}

func TestRenderLoginPageEscapesPrefill(t *testing.T) {
	rec := httptest.NewRecorder()
	renderLoginPage(rec, httptest.NewRequest(http.MethodGet, "/login", nil),
		http.StatusUnauthorized, "帳號或密碼錯誤", "<script>alert(1)</script>")
	if rec.Code != http.StatusUnauthorized {
		t.Fatalf("status = %d, want 401", rec.Code)
	}
	body := rec.Body.String()
	if strings.Contains(body, "<script>") {
		t.Fatal("預填帳號須經 HTML 轉義")
	}
	if !strings.Contains(body, "&lt;script&gt;") {
		t.Fatal("預填帳號應以轉義後的值輸出")
	}
	if !strings.Contains(body, "帳號或密碼錯誤") {
		t.Fatal("應顯示錯誤訊息")
	}
}

func TestVerifyCSRF(t *testing.T) {
	cookie := &http.Cookie{Name: csrfCookieName, Value: "token-A"}
	tests := []struct {
		name string
		req  *http.Request
		want bool
	}{
		{"相符", formPost("csrf_token=token-A&username=a&password=b", cookie), true},
		{"不相符", formPost("csrf_token=token-B&username=a&password=b", cookie), false},
		{"缺少 Cookie", formPost("csrf_token=token-A&username=a&password=b", nil), false},
		{"缺少欄位", formPost("username=a&password=b", cookie), false},
		{"空欄位", formPost("csrf_token=&username=a&password=b", cookie), false},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			if got := verifyCSRF(tt.req); got != tt.want {
				t.Fatalf("verifyCSRF() = %v, want %v", got, tt.want)
			}
		})
	}
}

// 表單流程的錯誤路徑都在查詢資料庫前回應,可用 nil db 測試。
func TestLoginHandlerFormRejections(t *testing.T) {
	h := loginHandler(nil)
	cookie := &http.Cookie{Name: csrfCookieName, Value: "token-A"}

	t.Run("CSRF 不符回 403 表單", func(t *testing.T) {
		rec := httptest.NewRecorder()
		h(rec, formPost("csrf_token=wrong&username=alice&password=sup3r-secret", cookie))
		if rec.Code != http.StatusForbidden {
			t.Fatalf("status = %d, want 403, body = %s", rec.Code, rec.Body.String())
		}
		if !strings.Contains(rec.Header().Get("Content-Type"), "text/html") {
			t.Fatalf("Content-Type = %q, want text/html", rec.Header().Get("Content-Type"))
		}
		if !strings.Contains(rec.Body.String(), "表單驗證失敗") {
			t.Fatal("應在表單中顯示 CSRF 錯誤訊息")
		}
	})

	t.Run("缺 password 回 400 表單並保留帳號", func(t *testing.T) {
		rec := httptest.NewRecorder()
		h(rec, formPost("csrf_token=token-A&username=alice&password=", cookie))
		if rec.Code != http.StatusBadRequest {
			t.Fatalf("status = %d, want 400", rec.Code)
		}
		body := rec.Body.String()
		if !strings.Contains(body, "password 不可為空") {
			t.Fatal("應顯示驗證錯誤訊息")
		}
		if !strings.Contains(body, `value="alice"`) {
			t.Fatal("應保留使用者輸入的帳號")
		}
	})

	t.Run("不支援的 Content-Type 回 JSON 415", func(t *testing.T) {
		rec := httptest.NewRecorder()
		req := httptest.NewRequest(http.MethodPost, "/login", strings.NewReader("x=1"))
		req.Header.Set("Content-Type", "text/plain")
		h(rec, req)
		if rec.Code != http.StatusUnsupportedMediaType {
			t.Fatalf("status = %d, want 415", rec.Code)
		}
		if !strings.Contains(rec.Body.String(), `"error"`) {
			t.Fatalf("非表單流程應回 JSON 錯誤: %s", rec.Body.String())
		}
	})
}