package middleware

import (
	"bytes"
	"encoding/json"
	"errors"
	"log"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"

	"github.com/gin-gonic/gin"

	"github.com/user-management-system/internal/config"
	apierrors "github.com/user-management-system/internal/pkg/errors"
	"github.com/user-management-system/internal/security"
)

func TestCORS_UsesConfiguredOrigins(t *testing.T) {
	gin.SetMode(gin.TestMode)
	SetCORSConfig(config.CORSConfig{
		AllowedOrigins:   []string{"https://app.example.com"},
		AllowCredentials: true,
	})
	t.Cleanup(func() {
		SetCORSConfig(config.CORSConfig{
			AllowedOrigins:   []string{"*"},
			AllowCredentials: true,
		})
	})

	recorder := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(recorder)
	c.Request = httptest.NewRequest(http.MethodOptions, "/api/v1/users", nil)
	c.Request.Header.Set("Origin", "https://app.example.com")
	c.Request.Header.Set("Access-Control-Request-Headers", "Authorization")

	CORS()(c)

	if recorder.Code != http.StatusNoContent {
		t.Fatalf("expected 204, got %d", recorder.Code)
	}
	if got := recorder.Header().Get("Access-Control-Allow-Origin"); got != "https://app.example.com" {
		t.Fatalf("unexpected allow origin: %s", got)
	}
	if got := recorder.Header().Get("Access-Control-Allow-Credentials"); got != "true" {
		t.Fatalf("expected credentials header to be 'true', got %q", got)
	}
}

func TestCORS_RejectsDisallowedOrigin(t *testing.T) {
	gin.SetMode(gin.TestMode)
	SetCORSConfig(config.CORSConfig{
		AllowedOrigins:   []string{"https://app.example.com"},
		AllowCredentials: false,
	})
	t.Cleanup(func() {
		SetCORSConfig(config.CORSConfig{
			AllowedOrigins:   []string{"*"},
			AllowCredentials: true,
		})
	})

	recorder := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(recorder)
	c.Request = httptest.NewRequest(http.MethodGet, "/api/v1/users", nil)
	c.Request.Header.Set("Origin", "https://evil.example.com")

	CORS()(c)

	if recorder.Code != http.StatusForbidden {
		t.Fatalf("expected 403, got %d", recorder.Code)
	}
}

func TestSanitizeQuery_MasksSensitiveValues(t *testing.T) {
	raw := "token=abc123&foo=bar&access_token=xyz&secret=s1"
	sanitized := sanitizeQuery(raw)

	if sanitized == "" {
		t.Fatal("expected sanitized query")
	}
	if sanitized == raw {
		t.Fatal("expected query to be sanitized")
	}
	for _, value := range []string{"abc123", "xyz", "s1"} {
		if strings.Contains(sanitized, value) {
			t.Fatalf("expected sensitive value %q to be masked in %q", value, sanitized)
		}
	}
	if sanitizeQuery("") != "" {
		t.Fatal("expected empty query to stay empty")
	}
}

func TestSecurityHeaders_AttachesExpectedHeaders(t *testing.T) {
	gin.SetMode(gin.TestMode)

	recorder := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(recorder)
	c.Request = httptest.NewRequest(http.MethodGet, "/api/v1/users", nil)

	SecurityHeaders()(c)

	if got := recorder.Header().Get("X-Content-Type-Options"); got != "nosniff" {
		t.Fatalf("unexpected nosniff header: %q", got)
	}
	if got := recorder.Header().Get("X-Frame-Options"); got != "DENY" {
		t.Fatalf("unexpected frame options: %q", got)
	}
	if got := recorder.Header().Get("Content-Security-Policy"); got == "" {
		t.Fatal("expected content security policy header")
	}
	if got := recorder.Header().Get("Strict-Transport-Security"); got != "" {
		t.Fatalf("did not expect hsts header for http request, got %q", got)
	}
}

func TestSecurityHeaders_AttachesHSTSForForwardedHTTPS(t *testing.T) {
	gin.SetMode(gin.TestMode)

	recorder := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(recorder)
	c.Request = httptest.NewRequest(http.MethodGet, "/api/v1/users", nil)
	c.Request.Header.Set("X-Forwarded-Proto", "https")

	SecurityHeaders()(c)

	if got := recorder.Header().Get("Strict-Transport-Security"); !strings.Contains(got, "max-age=31536000") {
		t.Fatalf("expected hsts header, got %q", got)
	}
}

func TestNoStoreSensitiveResponses_AttachesExpectedHeadersToAuthRoutes(t *testing.T) {
	gin.SetMode(gin.TestMode)

	recorder := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(recorder)
	c.Request = httptest.NewRequest(http.MethodGet, "/api/v1/auth/capabilities", nil)

	NoStoreSensitiveResponses()(c)

	if got := recorder.Header().Get("Cache-Control"); got != sensitiveNoStoreCacheControl {
		t.Fatalf("unexpected cache-control header: %q", got)
	}
	if got := recorder.Header().Get("Pragma"); got != "no-cache" {
		t.Fatalf("unexpected pragma header: %q", got)
	}
	if got := recorder.Header().Get("Expires"); got != "0" {
		t.Fatalf("unexpected expires header: %q", got)
	}
	if got := recorder.Header().Get("Surrogate-Control"); got != "no-store" {
		t.Fatalf("unexpected surrogate-control header: %q", got)
	}
}

func TestNoStoreSensitiveResponses_DoesNotAttachHeadersToNonAuthRoutes(t *testing.T) {
	gin.SetMode(gin.TestMode)

	recorder := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(recorder)
	c.Request = httptest.NewRequest(http.MethodGet, "/api/v1/users", nil)

	NoStoreSensitiveResponses()(c)

	if got := recorder.Header().Get("Cache-Control"); got != "" {
		t.Fatalf("did not expect cache-control header, got %q", got)
	}
}

// ---------- TraceID middleware ----------

func TestTraceID_GeneratesAndAttachesTraceID(t *testing.T) {
	gin.SetMode(gin.TestMode)

	recorder := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(recorder)
	c.Request = httptest.NewRequest(http.MethodGet, "/api/v1/users", nil)

	TraceID()(c)

	traceID := c.GetString("trace_id")
	if traceID == "" {
		t.Fatal("expected trace_id to be set")
	}
	if len(traceID) < 8 {
		t.Fatalf("trace_id should be reasonably long, got %q", traceID)
	}

	if got := recorder.Header().Get("X-Trace-ID"); got != traceID {
		t.Fatalf("expected X-Trace-ID header to match trace_id, got %q", got)
	}
}

func TestTraceID_ExtractsExistingTraceID(t *testing.T) {
	gin.SetMode(gin.TestMode)

	existingTraceID := "existing-trace-id-12345"
	recorder := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(recorder)
	c.Request = httptest.NewRequest(http.MethodGet, "/api/v1/users", nil)
	c.Request.Header.Set("X-Trace-ID", existingTraceID)

	TraceID()(c)

	traceID := c.GetString("trace_id")
	if traceID != existingTraceID {
		t.Fatalf("expected trace_id to be extracted from header, got %q", traceID)
	}
}

func TestTraceID_GetTraceIDHandlesMissingAndPresentValue(t *testing.T) {
	gin.SetMode(gin.TestMode)

	recorder := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(recorder)
	c.Request = httptest.NewRequest(http.MethodGet, "/api/v1/users", nil)

	if got := GetTraceID(c); got != "" {
		t.Fatalf("GetTraceID() = %q, want empty string", got)
	}

	c.Set(TraceIDKey, "trace-123")
	if got := GetTraceID(c); got != "trace-123" {
		t.Fatalf("GetTraceID() = %q, want trace-123", got)
	}
}

// ---------- Error handling middleware ----------

func TestErrorHandler_HandlesErrors(t *testing.T) {
	gin.SetMode(gin.TestMode)

	recorder := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(recorder)
	c.Request = httptest.NewRequest(http.MethodGet, "/api/v1/users", nil)

	c.Error(errors.New("test error"))

	ErrorHandler()(c)

	if recorder.Code != http.StatusInternalServerError {
		t.Fatalf("expected status 500, got %d", recorder.Code)
	}
}

func TestErrorHandler_ApplicationErrorPreservesStatusAndReason(t *testing.T) {
	gin.SetMode(gin.TestMode)

	recorder := httptest.NewRecorder()
	router := gin.New()
	router.Use(ErrorHandler())
	router.GET("/users", func(c *gin.Context) {
		_ = c.Error(apierrors.Forbidden("FORBIDDEN", "denied"))
	})

	req := httptest.NewRequest(http.MethodGet, "/users", nil)
	router.ServeHTTP(recorder, req)

	if recorder.Code != http.StatusForbidden {
		t.Fatalf("expected status 403, got %d", recorder.Code)
	}

	var body map[string]any
	if err := json.Unmarshal(recorder.Body.Bytes(), &body); err != nil {
		t.Fatalf("unmarshal body failed: %v", err)
	}
	if got := body["reason"]; got != "FORBIDDEN" {
		t.Fatalf("reason = %#v, want FORBIDDEN", got)
	}
	if got := body["message"]; got != "denied" {
		t.Fatalf("message = %#v, want denied", got)
	}
}

func TestRecover_HandlesPanic(t *testing.T) {
	gin.SetMode(gin.TestMode)

	recorder := httptest.NewRecorder()
	c, router := gin.CreateTestContext(recorder)
	c.Request = httptest.NewRequest(http.MethodGet, "/panic", nil)

	router.Use(Recover())
	router.GET("/panic", func(c *gin.Context) {
		panic("test panic")
	})

	router.ServeHTTP(recorder, c.Request)

	if recorder.Code != http.StatusInternalServerError {
		t.Fatalf("expected status 500 after panic, got %d", recorder.Code)
	}
}

func TestRecover_ReturnsInternalServerErrorPayload(t *testing.T) {
	gin.SetMode(gin.TestMode)

	recorder := httptest.NewRecorder()
	router := gin.New()
	router.Use(Recover())
	router.GET("/panic", func(c *gin.Context) {
		panic("boom")
	})

	req := httptest.NewRequest(http.MethodGet, "/panic", nil)
	router.ServeHTTP(recorder, req)

	if recorder.Code != http.StatusInternalServerError {
		t.Fatalf("expected status 500 after panic, got %d", recorder.Code)
	}

	var body map[string]any
	if err := json.Unmarshal(recorder.Body.Bytes(), &body); err != nil {
		t.Fatalf("unmarshal body failed: %v", err)
	}
	if got := body["code"]; got != float64(http.StatusInternalServerError) {
		t.Fatalf("code = %#v, want %d", got, http.StatusInternalServerError)
	}
}

func TestLogger_WritesSanitizedQueryAndErrorContext(t *testing.T) {
	gin.SetMode(gin.TestMode)

	var buf bytes.Buffer
	originalWriter := log.Writer()
	log.SetOutput(&buf)
	t.Cleanup(func() {
		log.SetOutput(originalWriter)
	})

	recorder := httptest.NewRecorder()
	router := gin.New()
	router.Use(TraceID())
	router.Use(Logger())
	router.GET("/users", func(c *gin.Context) {
		c.Set("user_id", int64(7))
		_ = c.Error(errors.New("boom"))
		c.Status(http.StatusAccepted)
	})

	req := httptest.NewRequest(http.MethodGet, "/users?token=secret&name=alice", nil)
	req.RemoteAddr = "203.0.113.5:1234"
	req.Header.Set("User-Agent", "logger-test")
	router.ServeHTTP(recorder, req)

	deadline := time.Now().Add(time.Second)
	for time.Now().Before(deadline) && !strings.Contains(buf.String(), "[Query] /users?name=alice&token=%2A%2A%2A") {
		time.Sleep(10 * time.Millisecond)
	}

	logOutput := buf.String()
	if !strings.Contains(logOutput, "[API]") {
		t.Fatalf("expected API log entry, got %q", logOutput)
	}
	if !strings.Contains(logOutput, "user_id: 7") {
		t.Fatalf("expected user id in logs, got %q", logOutput)
	}
	if !strings.Contains(logOutput, "[Error]") || !strings.Contains(logOutput, "boom") {
		t.Fatalf("expected error log entry, got %q", logOutput)
	}
	if strings.Contains(logOutput, "token=secret") {
		t.Fatalf("expected sanitized query string, got %q", logOutput)
	}
}

func TestLogger_DropsMalformedQueryString(t *testing.T) {
	gin.SetMode(gin.TestMode)

	var buf bytes.Buffer
	originalWriter := log.Writer()
	log.SetOutput(&buf)
	t.Cleanup(func() {
		log.SetOutput(originalWriter)
	})

	recorder := httptest.NewRecorder()
	router := gin.New()
	router.Use(Logger())
	router.GET("/users", func(c *gin.Context) {
		c.Status(http.StatusOK)
	})

	req := httptest.NewRequest(http.MethodGet, "/users?bad=%zz", nil)
	router.ServeHTTP(recorder, req)

	time.Sleep(25 * time.Millisecond)
	if strings.Contains(buf.String(), "[Query]") {
		t.Fatalf("expected malformed query to be skipped, got %q", buf.String())
	}
}

func TestResponseWrapper_SkipsSSEAndBinaryResponses(t *testing.T) {
	gin.SetMode(gin.TestMode)

	testCases := []struct {
		name        string
		path        string
		contentType string
	}{
		{name: "sse", path: "/stream", contentType: "text/event-stream"},
		{name: "binary", path: "/download", contentType: "application/octet-stream"},
		{name: "swagger", path: "/swagger/index.html", contentType: ""},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			recorder := httptest.NewRecorder()
			router := gin.New()
			router.Use(ResponseWrapper())
			router.GET(tc.path, func(c *gin.Context) {
				c.Header("Content-Type", "application/json")
				c.JSON(http.StatusOK, gin.H{"ok": true})
			})

			req := httptest.NewRequest(http.MethodGet, tc.path, nil)
			if tc.contentType != "" {
				req.Header.Set("Content-Type", tc.contentType)
			}
			router.ServeHTTP(recorder, req)

			if recorder.Code != http.StatusOK {
				t.Fatalf("expected 200, got %d", recorder.Code)
			}
			if got := recorder.Body.String(); got != `{"ok":true}` {
				t.Fatalf("body = %s, want raw payload", got)
			}
		})
	}
}

func TestResponseWrapper_BufferMethodsTrackStatusAndBody(t *testing.T) {
	recorder := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(recorder)
	wrapper := &responseWrapper{
		ResponseWriter: c.Writer,
		body:           bytes.NewBuffer(nil),
		statusCode:     http.StatusOK,
	}

	if _, err := wrapper.Write([]byte("abc")); err != nil {
		t.Fatalf("Write() error = %v", err)
	}
	if _, err := wrapper.WriteString("def"); err != nil {
		t.Fatalf("WriteString() error = %v", err)
	}
	wrapper.WriteHeader(http.StatusAccepted)

	if got := wrapper.body.String(); got != "abcdef" {
		t.Fatalf("buffered body = %q, want abcdef", got)
	}
	if wrapper.statusCode != http.StatusAccepted {
		t.Fatalf("statusCode = %d, want %d", wrapper.statusCode, http.StatusAccepted)
	}
}

func TestIPFilter_RealIPAndInternalOnly(t *testing.T) {
	gin.SetMode(gin.TestMode)

	filter := security.NewIPFilter()
	middleware := NewIPFilterMiddleware(filter, IPFilterConfig{
		TrustProxy:     true,
		TrustedProxies: []string{"10.0.0.2"},
	})

	recorder := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(recorder)
	c.Request = httptest.NewRequest(http.MethodGet, "/protected", nil)
	c.Request.RemoteAddr = "10.0.0.2:8080"
	c.Request.Header.Set("X-Forwarded-For", "198.51.100.10, 10.0.0.2")

	if got := middleware.realIP(c); got != "198.51.100.10" {
		t.Fatalf("realIP() = %q, want 198.51.100.10", got)
	}
	if !middleware.isTrustedProxy("10.0.0.2") {
		t.Fatal("expected trusted proxy match")
	}
	if middleware.isTrustedProxy("10.0.0.3") {
		t.Fatal("unexpected trusted proxy match")
	}

	if !isPrivateIP("127.0.0.1") {
		t.Fatal("expected loopback to be private")
	}
	if isPrivateIP("198.51.100.10") {
		t.Fatal("expected public address to be non-private")
	}

	allowed := httptest.NewRecorder()
	allowedRouter := gin.New()
	allowedRouter.Use(InternalOnly())
	allowedRouter.GET("/metrics", func(c *gin.Context) {
		c.Status(http.StatusOK)
	})
	allowedReq := httptest.NewRequest(http.MethodGet, "/metrics", nil)
	allowedReq.RemoteAddr = "127.0.0.1:12345"
	allowedRouter.ServeHTTP(allowed, allowedReq)
	if allowed.Code != http.StatusOK {
		t.Fatalf("expected private IP to pass, got %d", allowed.Code)
	}

	blocked := httptest.NewRecorder()
	blockedRouter := gin.New()
	blockedRouter.Use(InternalOnly())
	blockedRouter.GET("/metrics", func(c *gin.Context) {
		c.Status(http.StatusOK)
	})
	blockedReq := httptest.NewRequest(http.MethodGet, "/metrics", nil)
	blockedReq.RemoteAddr = "198.51.100.10:12345"
	blockedRouter.ServeHTTP(blocked, blockedReq)
	if blocked.Code != http.StatusForbidden {
		t.Fatalf("expected public IP to be rejected, got %d", blocked.Code)
	}
}

func TestIPFilter_FilterAndFallbacks(t *testing.T) {
	gin.SetMode(gin.TestMode)

	filter := security.NewIPFilter()
	if err := filter.AddToBlacklist("198.51.100.10", "manual", time.Minute); err != nil {
		t.Fatalf("AddToBlacklist() error = %v", err)
	}
	middleware := NewIPFilterMiddleware(filter, IPFilterConfig{})
	if middleware.GetFilter() != filter {
		t.Fatal("expected GetFilter() to expose the original filter")
	}

	blockedRecorder := httptest.NewRecorder()
	blockedRouter := gin.New()
	blockedRouter.Use(middleware.Filter())
	blockedRouter.GET("/protected", func(c *gin.Context) {
		c.Status(http.StatusOK)
	})
	blockedReq := httptest.NewRequest(http.MethodGet, "/protected", nil)
	blockedReq.RemoteAddr = "198.51.100.10:12345"
	blockedRouter.ServeHTTP(blockedRecorder, blockedReq)
	if blockedRecorder.Code != http.StatusForbidden {
		t.Fatalf("expected blocked IP to be rejected, got %d", blockedRecorder.Code)
	}

	allowedRecorder := httptest.NewRecorder()
	allowedRouter := gin.New()
	allowedRouter.Use(middleware.Filter())
	allowedRouter.GET("/protected", func(c *gin.Context) {
		if got := c.GetString("client_ip"); got != "127.0.0.1" {
			t.Fatalf("client_ip = %q, want 127.0.0.1", got)
		}
		c.Status(http.StatusOK)
	})
	allowedReq := httptest.NewRequest(http.MethodGet, "/protected", nil)
	allowedReq.RemoteAddr = "127.0.0.1:54321"
	allowedRouter.ServeHTTP(allowedRecorder, allowedReq)
	if allowedRecorder.Code != http.StatusOK {
		t.Fatalf("expected allowed IP to pass, got %d", allowedRecorder.Code)
	}

	trustedProxyMiddleware := NewIPFilterMiddleware(filter, IPFilterConfig{
		TrustProxy: true,
	})
	proxyRecorder := httptest.NewRecorder()
	proxyCtx, _ := gin.CreateTestContext(proxyRecorder)
	proxyCtx.Request = httptest.NewRequest(http.MethodGet, "/protected", nil)
	proxyCtx.Request.RemoteAddr = "10.0.0.2:8080"
	proxyCtx.Request.Header.Set("X-Real-IP", "203.0.113.9")
	if got := trustedProxyMiddleware.realIP(proxyCtx); got != "203.0.113.9" {
		t.Fatalf("realIP() X-Real-IP fallback = %q, want 203.0.113.9", got)
	}
}