package api

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

	"github.com/gin-gonic/gin"
)

func init() {
	gin.SetMode(gin.TestMode)
}

// TestIsAllowedOrigin 驗證 CORS 白名單判斷邏輯（M8-8 / TDD §4.2）。
func TestIsAllowedOrigin(t *testing.T) {
	cases := []struct {
		origin string
		want   bool
	}{
		// 白名單合法情境
		{"http://127.0.0.1:3721", true},
		{"http://127.0.0.1", true},
		{"http://localhost:3000", true},
		{"http://localhost:8080", true},
		{"http://localhost", true},
		{"http://[::1]:3721", true},
		{"http://LOCALHOST:9999", true}, // hostname 應大小寫不敏感

		// scheme 不對
		{"https://127.0.0.1:3721", false},
		{"https://localhost:3000", false},
		{"ws://127.0.0.1:3721", false},

		// hostname 不在白名單
		{"http://192.168.1.5:3721", false},
		{"http://example.com", false},
		{"http://malicious.local", false},
		{"http://127.0.0.1.evil.com", false}, // suffix 攻擊
		{"http://evil-127.0.0.1.com", false},

		// 特殊情境
		{"", false},
		{"null", false},
		{"http://", false},
		{"not-a-url", false},
	}

	for _, tc := range cases {
		got := isAllowedOrigin(tc.origin)
		if got != tc.want {
			t.Errorf("isAllowedOrigin(%q) = %v, want %v", tc.origin, got, tc.want)
		}
	}
}

// newTestRouter 建一台只掛 CORSMiddleware 的最小 router，用於測試 middleware 行為。
func newTestRouter() *gin.Engine {
	r := gin.New()
	r.Use(CORSMiddleware())
	r.GET("/api/ping", func(c *gin.Context) {
		c.JSON(http.StatusOK, gin.H{"ok": true})
	})
	r.POST("/api/do", func(c *gin.Context) {
		c.JSON(http.StatusOK, gin.H{"ok": true})
	})
	return r
}

// TestCORSMiddleware_AllowedOriginGET：白名單 Origin 的 GET 應回 200 且帶 ACA header。
func TestCORSMiddleware_AllowedOriginGET(t *testing.T) {
	r := newTestRouter()

	req := httptest.NewRequest(http.MethodGet, "/api/ping", nil)
	req.Header.Set("Origin", "http://127.0.0.1:3000")
	w := httptest.NewRecorder()
	r.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", w.Code)
	}
	if got := w.Header().Get("Access-Control-Allow-Origin"); got != "http://127.0.0.1:3000" {
		t.Errorf("ACA-Origin = %q, want http://127.0.0.1:3000", got)
	}
	if got := w.Header().Get("Access-Control-Allow-Credentials"); got != "true" {
		t.Errorf("ACA-Credentials = %q, want true", got)
	}
	if got := w.Header().Get("Vary"); got != "Origin" {
		t.Errorf("Vary = %q, want Origin", got)
	}
}

// TestCORSMiddleware_LocalhostAllowed：localhost 任意 port 都應放行。
func TestCORSMiddleware_LocalhostAllowed(t *testing.T) {
	r := newTestRouter()

	req := httptest.NewRequest(http.MethodGet, "/api/ping", nil)
	req.Header.Set("Origin", "http://localhost:8080")
	w := httptest.NewRecorder()
	r.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", w.Code)
	}
	if got := w.Header().Get("Access-Control-Allow-Origin"); got != "http://localhost:8080" {
		t.Errorf("ACA-Origin = %q, want http://localhost:8080", got)
	}
}

// TestCORSMiddleware_DisallowedOriginPOST：非白名單 Origin 的 POST 必須 403。
func TestCORSMiddleware_DisallowedOriginPOST(t *testing.T) {
	r := newTestRouter()

	req := httptest.NewRequest(http.MethodPost, "/api/do", nil)
	req.Header.Set("Origin", "https://example.com")
	w := httptest.NewRecorder()
	r.ServeHTTP(w, req)

	if w.Code != http.StatusForbidden {
		t.Fatalf("status = %d, want 403", w.Code)
	}
	if got := w.Header().Get("Access-Control-Allow-Origin"); got != "" {
		t.Errorf("非白名單不應回 ACA-Origin，got %q", got)
	}
}

// TestCORSMiddleware_DisallowedOriginGET：非白名單 GET 應該執行 handler 但不回 ACA。
func TestCORSMiddleware_DisallowedOriginGET(t *testing.T) {
	r := newTestRouter()

	req := httptest.NewRequest(http.MethodGet, "/api/ping", nil)
	req.Header.Set("Origin", "http://malicious.local")
	w := httptest.NewRecorder()
	r.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200 (handler 仍執行，瀏覽器層擋讀取)", w.Code)
	}
	if got := w.Header().Get("Access-Control-Allow-Origin"); got != "" {
		t.Errorf("非白名單不應回 ACA-Origin，got %q", got)
	}
}

// TestCORSMiddleware_PreflightAllowed：白名單 Origin 的 OPTIONS preflight 應回 204 + 完整 headers。
func TestCORSMiddleware_PreflightAllowed(t *testing.T) {
	r := newTestRouter()

	req := httptest.NewRequest(http.MethodOptions, "/api/do", nil)
	req.Header.Set("Origin", "http://127.0.0.1:9999")
	req.Header.Set("Access-Control-Request-Method", "POST")
	req.Header.Set("Access-Control-Request-Headers", "Content-Type")
	w := httptest.NewRecorder()
	r.ServeHTTP(w, req)

	if w.Code != http.StatusNoContent {
		t.Fatalf("status = %d, want 204", w.Code)
	}
	if got := w.Header().Get("Access-Control-Allow-Origin"); got != "http://127.0.0.1:9999" {
		t.Errorf("ACA-Origin = %q, want http://127.0.0.1:9999", got)
	}
	if got := w.Header().Get("Access-Control-Allow-Methods"); got == "" {
		t.Errorf("ACA-Methods 不應為空")
	}
	if got := w.Header().Get("Access-Control-Allow-Headers"); got == "" {
		t.Errorf("ACA-Headers 不應為空")
	}
}

// TestCORSMiddleware_PreflightDisallowed：非白名單 OPTIONS preflight 應 403，不回 ACA。
func TestCORSMiddleware_PreflightDisallowed(t *testing.T) {
	r := newTestRouter()

	req := httptest.NewRequest(http.MethodOptions, "/api/do", nil)
	req.Header.Set("Origin", "http://evil.com")
	req.Header.Set("Access-Control-Request-Method", "POST")
	w := httptest.NewRecorder()
	r.ServeHTTP(w, req)

	if w.Code != http.StatusForbidden {
		t.Fatalf("status = %d, want 403", w.Code)
	}
	if got := w.Header().Get("Access-Control-Allow-Origin"); got != "" {
		t.Errorf("非白名單不應回 ACA-Origin，got %q", got)
	}
}

// TestCORSMiddleware_SameOrigin：沒帶 Origin（same-origin）應放行。
func TestCORSMiddleware_SameOrigin(t *testing.T) {
	r := newTestRouter()

	req := httptest.NewRequest(http.MethodGet, "/api/ping", nil)
	w := httptest.NewRecorder()
	r.ServeHTTP(w, req)

	if w.Code != http.StatusOK {
		t.Fatalf("status = %d, want 200", w.Code)
	}
	if got := w.Header().Get("Access-Control-Allow-Origin"); got != "" {
		t.Errorf("same-origin 不應回 ACA-Origin，got %q", got)
	}
}