package middleware

import (
	"bytes"
	"context"
	"crypto/ed25519"
	"crypto/rand"
	"log/slog"
	"net"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"

	"git.wntrmute.dev/kyle/mcias/internal/db"
	"git.wntrmute.dev/kyle/mcias/internal/model"
	"git.wntrmute.dev/kyle/mcias/internal/token"
)

func generateTestKey(t *testing.T) (ed25519.PublicKey, ed25519.PrivateKey) {
	t.Helper()
	pub, priv, err := ed25519.GenerateKey(rand.Reader)
	if err != nil {
		t.Fatalf("generate test key: %v", err)
	}
	return pub, priv
}

func openTestDB(t *testing.T) *db.DB {
	t.Helper()
	database, err := db.Open(":memory:")
	if err != nil {
		t.Fatalf("open test db: %v", err)
	}
	if err := db.Migrate(database); err != nil {
		t.Fatalf("migrate test db: %v", err)
	}
	t.Cleanup(func() { _ = database.Close() })
	return database
}

const testIssuer = "https://auth.example.com"

// issueAndTrackToken creates a valid JWT and records it in the DB.
func issueAndTrackToken(t *testing.T, priv ed25519.PrivateKey, database *db.DB, accountID int64, roles []string) string {
	t.Helper()
	tokenStr, claims, err := token.IssueToken(priv, testIssuer, "user-uuid", roles, time.Hour)
	if err != nil {
		t.Fatalf("IssueToken: %v", err)
	}
	if err := database.TrackToken(claims.JTI, accountID, claims.IssuedAt, claims.ExpiresAt); err != nil {
		t.Fatalf("TrackToken: %v", err)
	}
	return tokenStr
}

func TestRequestLogger(t *testing.T) {
	var buf bytes.Buffer
	logger := slog.New(slog.NewTextHandler(&buf, nil))

	handler := RequestLogger(logger)(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(http.StatusOK)
	}))

	req := httptest.NewRequest(http.MethodGet, "/v1/health", nil)
	rr := httptest.NewRecorder()
	handler.ServeHTTP(rr, req)

	if rr.Code != http.StatusOK {
		t.Errorf("status = %d, want 200", rr.Code)
	}
	logOutput := buf.String()
	if logOutput == "" {
		t.Error("expected log output, got empty string")
	}
	// Security: Authorization header must not appear in logs.
	req2 := httptest.NewRequest(http.MethodGet, "/v1/health", nil)
	req2.Header.Set("Authorization", "Bearer secret-token-value")
	buf.Reset()
	rr2 := httptest.NewRecorder()
	handler.ServeHTTP(rr2, req2)
	if bytes.Contains(buf.Bytes(), []byte("secret-token-value")) {
		t.Error("log output contains Authorization token value — credential leak!")
	}
}

func TestRequireAuthValid(t *testing.T) {
	pub, priv := generateTestKey(t)
	database := openTestDB(t)

	acct, err := database.CreateAccount("alice", model.AccountTypeHuman, "hash")
	if err != nil {
		t.Fatalf("CreateAccount: %v", err)
	}

	tokenStr := issueAndTrackToken(t, priv, database, acct.ID, []string{"reader"})

	reached := false
	handler := RequireAuth(pub, database, testIssuer)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		reached = true
		claims := ClaimsFromContext(r.Context())
		if claims == nil {
			t.Error("claims not in context")
		}
		w.WriteHeader(http.StatusOK)
	}))

	req := httptest.NewRequest(http.MethodGet, "/v1/test", nil)
	req.Header.Set("Authorization", "Bearer "+tokenStr)
	rr := httptest.NewRecorder()
	handler.ServeHTTP(rr, req)

	if rr.Code != http.StatusOK {
		t.Errorf("status = %d, want 200; body: %s", rr.Code, rr.Body.String())
	}
	if !reached {
		t.Error("handler was not reached with valid token")
	}
}

func TestRequireAuthMissingHeader(t *testing.T) {
	pub, priv := generateTestKey(t)
	_ = priv
	database := openTestDB(t)

	handler := RequireAuth(pub, database, testIssuer)(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		t.Error("handler should not be reached without auth")
		w.WriteHeader(http.StatusOK)
	}))

	req := httptest.NewRequest(http.MethodGet, "/v1/test", nil)
	rr := httptest.NewRecorder()
	handler.ServeHTTP(rr, req)

	if rr.Code != http.StatusUnauthorized {
		t.Errorf("status = %d, want 401", rr.Code)
	}
}

func TestRequireAuthInvalidToken(t *testing.T) {
	pub, _ := generateTestKey(t)
	database := openTestDB(t)

	handler := RequireAuth(pub, database, testIssuer)(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		t.Error("handler should not be reached with invalid token")
		w.WriteHeader(http.StatusOK)
	}))

	req := httptest.NewRequest(http.MethodGet, "/v1/test", nil)
	req.Header.Set("Authorization", "Bearer not.a.valid.jwt")
	rr := httptest.NewRecorder()
	handler.ServeHTTP(rr, req)

	if rr.Code != http.StatusUnauthorized {
		t.Errorf("status = %d, want 401", rr.Code)
	}
}

func TestRequireAuthRevokedToken(t *testing.T) {
	pub, priv := generateTestKey(t)
	database := openTestDB(t)

	acct, err := database.CreateAccount("bob", model.AccountTypeHuman, "hash")
	if err != nil {
		t.Fatalf("CreateAccount: %v", err)
	}

	tokenStr := issueAndTrackToken(t, priv, database, acct.ID, nil)

	// Extract JTI and revoke the token.
	claims, err := token.ValidateToken(pub, tokenStr, testIssuer)
	if err != nil {
		t.Fatalf("ValidateToken: %v", err)
	}
	if err := database.RevokeToken(claims.JTI, "test revocation"); err != nil {
		t.Fatalf("RevokeToken: %v", err)
	}

	handler := RequireAuth(pub, database, testIssuer)(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		t.Error("handler should not be reached with revoked token")
		w.WriteHeader(http.StatusOK)
	}))

	req := httptest.NewRequest(http.MethodGet, "/v1/test", nil)
	req.Header.Set("Authorization", "Bearer "+tokenStr)
	rr := httptest.NewRecorder()
	handler.ServeHTTP(rr, req)

	if rr.Code != http.StatusUnauthorized {
		t.Errorf("status = %d, want 401", rr.Code)
	}
}

func TestRequireAuthExpiredToken(t *testing.T) {
	pub, priv := generateTestKey(t)
	database := openTestDB(t)

	// Issue an already-expired token.
	tokenStr, _, err := token.IssueToken(priv, testIssuer, "user-uuid", nil, -time.Minute)
	if err != nil {
		t.Fatalf("IssueToken: %v", err)
	}

	handler := RequireAuth(pub, database, testIssuer)(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		t.Error("handler should not be reached with expired token")
		w.WriteHeader(http.StatusOK)
	}))

	req := httptest.NewRequest(http.MethodGet, "/v1/test", nil)
	req.Header.Set("Authorization", "Bearer "+tokenStr)
	rr := httptest.NewRecorder()
	handler.ServeHTTP(rr, req)

	if rr.Code != http.StatusUnauthorized {
		t.Errorf("status = %d, want 401", rr.Code)
	}
}

func TestRequireRoleGranted(t *testing.T) {
	claims := &token.Claims{Roles: []string{"admin"}}
	ctx := context.WithValue(context.Background(), claimsKey, claims)

	reached := false
	handler := RequireRole("admin")(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		reached = true
		w.WriteHeader(http.StatusOK)
	}))

	req := httptest.NewRequest(http.MethodGet, "/", nil).WithContext(ctx)
	rr := httptest.NewRecorder()
	handler.ServeHTTP(rr, req)

	if rr.Code != http.StatusOK {
		t.Errorf("status = %d, want 200", rr.Code)
	}
	if !reached {
		t.Error("handler not reached with correct role")
	}
}

func TestRequireRoleForbidden(t *testing.T) {
	claims := &token.Claims{Roles: []string{"reader"}}
	ctx := context.WithValue(context.Background(), claimsKey, claims)

	handler := RequireRole("admin")(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		t.Error("handler should not be reached without admin role")
		w.WriteHeader(http.StatusOK)
	}))

	req := httptest.NewRequest(http.MethodGet, "/", nil).WithContext(ctx)
	rr := httptest.NewRecorder()
	handler.ServeHTTP(rr, req)

	if rr.Code != http.StatusForbidden {
		t.Errorf("status = %d, want 403", rr.Code)
	}
}

func TestRequireRoleNoClaims(t *testing.T) {
	handler := RequireRole("admin")(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		t.Error("handler should not be reached without claims in context")
		w.WriteHeader(http.StatusOK)
	}))

	req := httptest.NewRequest(http.MethodGet, "/", nil)
	rr := httptest.NewRecorder()
	handler.ServeHTTP(rr, req)

	if rr.Code != http.StatusForbidden {
		t.Errorf("status = %d, want 403", rr.Code)
	}
}

func TestRateLimitAllows(t *testing.T) {
	handler := RateLimit(10, 5, nil)(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(http.StatusOK)
	}))

	req := httptest.NewRequest(http.MethodPost, "/v1/auth/login", nil)
	req.RemoteAddr = "127.0.0.1:12345"

	// First 5 requests should be allowed (burst=5).
	for i := range 5 {
		rr := httptest.NewRecorder()
		handler.ServeHTTP(rr, req)
		if rr.Code != http.StatusOK {
			t.Errorf("request %d: status = %d, want 200", i+1, rr.Code)
		}
	}
}

func TestRateLimitBlocks(t *testing.T) {
	handler := RateLimit(0.1, 2, nil)(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(http.StatusOK)
	}))

	req := httptest.NewRequest(http.MethodPost, "/v1/auth/login", nil)
	req.RemoteAddr = "10.0.0.1:9999"

	// Exhaust the burst of 2.
	for range 2 {
		rr := httptest.NewRecorder()
		handler.ServeHTTP(rr, req)
	}

	// Next request should be rate-limited.
	rr := httptest.NewRecorder()
	handler.ServeHTTP(rr, req)
	if rr.Code != http.StatusTooManyRequests {
		t.Errorf("status = %d, want 429 after burst exceeded", rr.Code)
	}
}

func TestExtractBearerToken(t *testing.T) {
	tests := []struct {
		name    string
		header  string
		want    string
		wantErr bool
	}{
		{"valid", "Bearer mytoken123", "mytoken123", false},
		{"missing header", "", "", true},
		{"no bearer prefix", "Token mytoken123", "", true},
		{"empty token", "Bearer ", "", true},
		{"case insensitive", "bearer mytoken123", "mytoken123", false},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			req := httptest.NewRequest(http.MethodGet, "/", nil)
			if tc.header != "" {
				req.Header.Set("Authorization", tc.header)
			}
			got, err := extractBearerToken(req)
			if (err != nil) != tc.wantErr {
				t.Errorf("wantErr=%v, got err=%v", tc.wantErr, err)
			}
			if !tc.wantErr && got != tc.want {
				t.Errorf("token = %q, want %q", got, tc.want)
			}
		})
	}
}

// TestClientIP verifies the proxy-aware IP extraction logic.
func TestClientIP(t *testing.T) {
	proxy := net.ParseIP("10.0.0.1")

	tests := []struct {
		name          string
		remoteAddr    string
		xForwardedFor string
		xRealIP       string
		trustedProxy  net.IP
		want          string
	}{
		{
			name:       "no proxy configured: uses RemoteAddr",
			remoteAddr: "203.0.113.5:54321",
			want:       "203.0.113.5",
		},
		{
			name:          "proxy configured but request not from proxy: uses RemoteAddr",
			remoteAddr:    "198.51.100.9:12345",
			xForwardedFor: "203.0.113.99",
			trustedProxy:  proxy,
			want:          "198.51.100.9",
		},
		{
			name:          "request from trusted proxy with X-Real-IP: uses X-Real-IP",
			remoteAddr:    "10.0.0.1:8080",
			xRealIP:       "203.0.113.42",
			trustedProxy:  proxy,
			want:          "203.0.113.42",
		},
		{
			name:          "request from trusted proxy with X-Forwarded-For: uses first entry",
			remoteAddr:    "10.0.0.1:8080",
			xForwardedFor: "203.0.113.77, 10.0.0.2",
			trustedProxy:  proxy,
			want:          "203.0.113.77",
		},
		{
			name:          "X-Real-IP takes precedence over X-Forwarded-For",
			remoteAddr:    "10.0.0.1:8080",
			xRealIP:       "203.0.113.11",
			xForwardedFor: "203.0.113.22",
			trustedProxy:  proxy,
			want:          "203.0.113.11",
		},
		{
			name:          "proxy request with invalid X-Real-IP falls back to X-Forwarded-For",
			remoteAddr:    "10.0.0.1:8080",
			xRealIP:       "not-an-ip",
			xForwardedFor: "203.0.113.55",
			trustedProxy:  proxy,
			want:          "203.0.113.55",
		},
		{
			name:          "proxy request with no forwarding headers falls back to RemoteAddr host",
			remoteAddr:    "10.0.0.1:8080",
			trustedProxy:  proxy,
			want:          "10.0.0.1",
		},
		{
			// Security: attacker fakes X-Forwarded-For but connects directly.
			name:          "spoofed X-Forwarded-For from non-proxy IP is ignored",
			remoteAddr:    "198.51.100.99:9999",
			xForwardedFor: "127.0.0.1",
			trustedProxy:  proxy,
			want:          "198.51.100.99",
		},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			req := httptest.NewRequest(http.MethodGet, "/", nil)
			req.RemoteAddr = tc.remoteAddr
			if tc.xForwardedFor != "" {
				req.Header.Set("X-Forwarded-For", tc.xForwardedFor)
			}
			if tc.xRealIP != "" {
				req.Header.Set("X-Real-IP", tc.xRealIP)
			}
			got := ClientIP(req, tc.trustedProxy)
			if got != tc.want {
				t.Errorf("ClientIP = %q, want %q", got, tc.want)
			}
		})
	}
}

// TestRateLimitTrustedProxy verifies that rate limiting uses the forwarded IP
// when the request originates from a trusted proxy.
func TestRateLimitTrustedProxy(t *testing.T) {
	proxy := net.ParseIP("10.0.0.1")
	// Very low rps and burst=1 so any two requests from the same IP are blocked.
	handler := RateLimit(0.001, 1, proxy)(http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(http.StatusOK)
	}))

	// Two requests from the same real client IP, forwarded by the proxy.
	// Both carry the same X-Real-IP; the second should be rate-limited.
	for i, wantStatus := range []int{http.StatusOK, http.StatusTooManyRequests} {
		req := httptest.NewRequest(http.MethodPost, "/v1/auth/login", nil)
		req.RemoteAddr = "10.0.0.1:5000" // from the trusted proxy
		req.Header.Set("X-Real-IP", "203.0.113.5")
		rr := httptest.NewRecorder()
		handler.ServeHTTP(rr, req)
		if rr.Code != wantStatus {
			t.Errorf("request %d: status = %d, want %d", i+1, rr.Code, wantStatus)
		}
	}

	// A different real client (different X-Real-IP) should still be allowed.
	req := httptest.NewRequest(http.MethodPost, "/v1/auth/login", nil)
	req.RemoteAddr = "10.0.0.1:5001"
	req.Header.Set("X-Real-IP", "203.0.113.99")
	rr := httptest.NewRecorder()
	handler.ServeHTTP(rr, req)
	if rr.Code != http.StatusOK {
		t.Errorf("distinct client: status = %d, want 200 (separate bucket)", rr.Code)
	}
}