package server_test

import (
	"bytes"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"regexp"
	"strings"
	"testing"

	"git.codelab.vc/pkg/httpx/server"
)

func TestChain(t *testing.T) {
	t.Run("applies middlewares in correct order", func(t *testing.T) {
		var order []string

		mwA := func(next http.Handler) http.Handler {
			return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
				order = append(order, "A-before")
				next.ServeHTTP(w, r)
				order = append(order, "A-after")
			})
		}

		mwB := func(next http.Handler) http.Handler {
			return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
				order = append(order, "B-before")
				next.ServeHTTP(w, r)
				order = append(order, "B-after")
			})
		}

		handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
			order = append(order, "handler")
			w.WriteHeader(http.StatusOK)
		})

		chained := server.Chain(mwA, mwB)(handler)

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

		expected := []string{"A-before", "B-before", "handler", "B-after", "A-after"}
		if len(order) != len(expected) {
			t.Fatalf("got %v, want %v", order, expected)
		}
		for i, v := range expected {
			if order[i] != v {
				t.Fatalf("order[%d] = %q, want %q", i, order[i], v)
			}
		}
	})

	t.Run("empty chain returns handler unchanged", func(t *testing.T) {
		called := false
		handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
			called = true
			w.WriteHeader(http.StatusOK)
		})

		chained := server.Chain()(handler)

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

		if !called {
			t.Fatal("handler was not called")
		}
	})
}

func TestChain_SingleMiddleware(t *testing.T) {
	var called bool
	mw := func(next http.Handler) http.Handler {
		return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			called = true
			next.ServeHTTP(w, r)
		})
	}

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

	chained := server.Chain(mw)(handler)

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

	if !called {
		t.Fatal("single middleware was not called")
	}
	if w.Code != http.StatusOK {
		t.Fatalf("got status %d, want %d", w.Code, http.StatusOK)
	}
}

func TestStatusWriter_WriteHeaderMultipleCalls(t *testing.T) {
	handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		w.WriteHeader(http.StatusCreated)
		w.WriteHeader(http.StatusNotFound) // second call should not change captured status
	})

	var buf bytes.Buffer
	logger := slog.New(slog.NewTextHandler(&buf, nil))
	mw := server.Logging(logger)(handler)

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

	if !strings.Contains(buf.String(), "status=201") {
		t.Fatalf("expected status=201 (first WriteHeader call captured), got %q", buf.String())
	}
}

func TestStatusWriter_WriteDefaultsTo200(t *testing.T) {
	handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		_, _ = w.Write([]byte("hello")) // Write without WriteHeader
	})

	var buf bytes.Buffer
	logger := slog.New(slog.NewTextHandler(&buf, nil))
	mw := server.Logging(logger)(handler)

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

	if !strings.Contains(buf.String(), "status=200") {
		t.Fatalf("expected status=200 when Write called without WriteHeader, got %q", buf.String())
	}
}

func TestStatusWriter_Unwrap(t *testing.T) {
	handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		rc := http.NewResponseController(w)
		if err := rc.Flush(); err != nil {
			// httptest.ResponseRecorder implements Flusher, so this should succeed
			// if Unwrap works correctly.
			http.Error(w, "flush failed", http.StatusInternalServerError)
			return
		}
		w.WriteHeader(http.StatusOK)
	})

	// Use Logging to wrap in statusWriter
	var buf bytes.Buffer
	logger := slog.New(slog.NewTextHandler(&buf, nil))
	mw := server.Logging(logger)(handler)

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

	if w.Code == http.StatusInternalServerError {
		t.Fatal("Flush failed — Unwrap likely not exposing underlying Flusher")
	}
}

func TestRequestID(t *testing.T) {
	t.Run("generates ID when not present", func(t *testing.T) {
		var gotID string
		handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			gotID = server.RequestIDFromContext(r.Context())
			w.WriteHeader(http.StatusOK)
		})

		mw := server.RequestID()(handler)

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

		if gotID == "" {
			t.Fatal("expected request ID in context, got empty")
		}
		if w.Header().Get("X-Request-Id") != gotID {
			t.Fatalf("response header %q != context ID %q", w.Header().Get("X-Request-Id"), gotID)
		}
		// UUID v4 format: 8-4-4-4-12 hex chars.
		if len(gotID) != 36 {
			t.Fatalf("expected UUID length 36, got %d: %q", len(gotID), gotID)
		}
	})

	t.Run("preserves existing ID", func(t *testing.T) {
		var gotID string
		handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			gotID = server.RequestIDFromContext(r.Context())
			w.WriteHeader(http.StatusOK)
		})

		mw := server.RequestID()(handler)

		w := httptest.NewRecorder()
		req := httptest.NewRequest(http.MethodGet, "/", nil)
		req.Header.Set("X-Request-Id", "custom-123")
		mw.ServeHTTP(w, req)

		if gotID != "custom-123" {
			t.Fatalf("got ID %q, want %q", gotID, "custom-123")
		}
	})

	t.Run("context without ID returns empty", func(t *testing.T) {
		req := httptest.NewRequest(http.MethodGet, "/", nil)
		if id := server.RequestIDFromContext(req.Context()); id != "" {
			t.Fatalf("expected empty, got %q", id)
		}
	})
}

func TestRequestID_UUIDFormat(t *testing.T) {
	uuidV4Re := regexp.MustCompile(`^[0-9a-f]{8}-[0-9a-f]{4}-4[0-9a-f]{3}-[89ab][0-9a-f]{3}-[0-9a-f]{12}$`)

	var gotID string
	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		gotID = server.RequestIDFromContext(r.Context())
		w.WriteHeader(http.StatusOK)
	})

	mw := server.RequestID()(handler)

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

	if !uuidV4Re.MatchString(gotID) {
		t.Fatalf("generated ID %q does not match UUID v4 format", gotID)
	}
}

func TestRequestID_Uniqueness(t *testing.T) {
	seen := make(map[string]struct{}, 1000)

	handler := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		id := server.RequestIDFromContext(r.Context())
		if _, exists := seen[id]; exists {
			t.Fatalf("duplicate request ID: %q", id)
		}
		seen[id] = struct{}{}
		w.WriteHeader(http.StatusOK)
	})

	mw := server.RequestID()(handler)

	for i := 0; i < 1000; i++ {
		w := httptest.NewRecorder()
		req := httptest.NewRequest(http.MethodGet, "/", nil)
		mw.ServeHTTP(w, req)
	}

	if len(seen) != 1000 {
		t.Fatalf("expected 1000 unique IDs, got %d", len(seen))
	}
}

func TestRecovery(t *testing.T) {
	t.Run("recovers from panic and returns 500", func(t *testing.T) {
		handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
			panic("something went wrong")
		})

		mw := server.Recovery()(handler)

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

		if w.Code != http.StatusInternalServerError {
			t.Fatalf("got status %d, want %d", w.Code, http.StatusInternalServerError)
		}
	})

	t.Run("logs panic with logger", func(t *testing.T) {
		var buf bytes.Buffer
		logger := slog.New(slog.NewTextHandler(&buf, nil))

		handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
			panic("boom")
		})

		mw := server.Recovery(server.WithRecoveryLogger(logger))(handler)

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

		if !strings.Contains(buf.String(), "panic recovered") {
			t.Fatalf("expected log to contain 'panic recovered', got %q", buf.String())
		}
		if !strings.Contains(buf.String(), "boom") {
			t.Fatalf("expected log to contain 'boom', got %q", buf.String())
		}
	})

	t.Run("passes through without panic", func(t *testing.T) {
		handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
			w.WriteHeader(http.StatusOK)
			_, _ = w.Write([]byte("ok"))
		})

		mw := server.Recovery()(handler)

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

		if w.Code != http.StatusOK {
			t.Fatalf("got status %d, want %d", w.Code, http.StatusOK)
		}
	})
}

func TestRecovery_PanicWithNonString(t *testing.T) {
	tests := []struct {
		name  string
		value any
	}{
		{"integer", 42},
		{"struct", struct{ X int }{X: 1}},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
				panic(tt.value)
			})

			var buf bytes.Buffer
			logger := slog.New(slog.NewTextHandler(&buf, nil))
			mw := server.Recovery(server.WithRecoveryLogger(logger))(handler)

			w := httptest.NewRecorder()
			req := httptest.NewRequest(http.MethodGet, "/test", nil)
			mw.ServeHTTP(w, req)

			if w.Code != http.StatusInternalServerError {
				t.Fatalf("got status %d, want %d", w.Code, http.StatusInternalServerError)
			}
			if !strings.Contains(buf.String(), "panic recovered") {
				t.Fatalf("expected 'panic recovered' in log, got %q", buf.String())
			}
		})
	}
}

func TestRecovery_ResponseBody(t *testing.T) {
	handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		panic("fail")
	})

	mw := server.Recovery()(handler)

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

	body := strings.TrimSpace(w.Body.String())
	if body != "Internal Server Error" {
		t.Fatalf("got body %q, want %q", body, "Internal Server Error")
	}
}

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

	// Put RequestID before Recovery so request_id is in context
	handler := server.RequestID()(
		server.Recovery(server.WithRecoveryLogger(logger))(
			http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
				panic("boom")
			}),
		),
	)

	w := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodPost, "/api/test", nil)
	handler.ServeHTTP(w, req)

	logOutput := buf.String()
	for _, attr := range []string{"method=", "path=", "request_id="} {
		if !strings.Contains(logOutput, attr) {
			t.Fatalf("expected %q in log, got %q", attr, logOutput)
		}
	}
}

func TestLogging(t *testing.T) {
	t.Run("logs request details", func(t *testing.T) {
		var buf bytes.Buffer
		logger := slog.New(slog.NewTextHandler(&buf, nil))

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

		mw := server.Logging(logger)(handler)

		w := httptest.NewRecorder()
		req := httptest.NewRequest(http.MethodPost, "/api/users", nil)
		mw.ServeHTTP(w, req)

		logOutput := buf.String()
		if !strings.Contains(logOutput, "request completed") {
			t.Fatalf("expected 'request completed' in log, got %q", logOutput)
		}
		if !strings.Contains(logOutput, "POST") {
			t.Fatalf("expected method in log, got %q", logOutput)
		}
		if !strings.Contains(logOutput, "/api/users") {
			t.Fatalf("expected path in log, got %q", logOutput)
		}
		if !strings.Contains(logOutput, "status=201") {
			t.Fatalf("expected status=201 in log, got %q", logOutput)
		}
	})

	t.Run("logs error level for 5xx", func(t *testing.T) {
		var buf bytes.Buffer
		logger := slog.New(slog.NewTextHandler(&buf, nil))

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

		mw := server.Logging(logger)(handler)

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

		logOutput := buf.String()
		if !strings.Contains(logOutput, "level=ERROR") {
			t.Fatalf("expected ERROR level in log, got %q", logOutput)
		}
	})
}

func TestLogging_4xxIsInfoLevel(t *testing.T) {
	var buf bytes.Buffer
	logger := slog.New(slog.NewTextHandler(&buf, nil))

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

	mw := server.Logging(logger)(handler)

	w := httptest.NewRecorder()
	req := httptest.NewRequest(http.MethodGet, "/missing", nil)
	mw.ServeHTTP(w, req)

	logOutput := buf.String()
	if !strings.Contains(logOutput, "level=INFO") {
		t.Fatalf("expected INFO level for 404, got %q", logOutput)
	}
	if strings.Contains(logOutput, "level=ERROR") {
		t.Fatalf("404 should not be logged as ERROR, got %q", logOutput)
	}
}

func TestLogging_DefaultStatus200(t *testing.T) {
	var buf bytes.Buffer
	logger := slog.New(slog.NewTextHandler(&buf, nil))

	handler := http.HandlerFunc(func(w http.ResponseWriter, _ *http.Request) {
		_, _ = w.Write([]byte("hello"))
	})

	mw := server.Logging(logger)(handler)

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

	if !strings.Contains(buf.String(), "status=200") {
		t.Fatalf("expected status=200 in log when handler only calls Write, got %q", buf.String())
	}
}

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

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

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

	if !strings.Contains(buf.String(), "request_id=") {
		t.Fatalf("expected request_id in log output, got %q", buf.String())
	}
}