package observability

import (
	"bytes"
	"encoding/json"
	"io"
	"log/slog"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"
)

func TestRequestIDSetsHeaderAndContext(t *testing.T) {
	handler := RequestID()(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if got := RequestIDFromContext(r.Context()); got == "" {
			t.Fatal("RequestIDFromContext() = empty, want non-empty")
		}
		w.WriteHeader(http.StatusNoContent)
	}))

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

	if rec.Header().Get("X-Request-Id") == "" {
		t.Fatal("X-Request-Id header = empty, want non-empty")
	}
}

func TestTimeoutAddsContextDeadline(t *testing.T) {
	handler := Timeout(50 * time.Millisecond)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		if _, ok := r.Context().Deadline(); !ok {
			t.Fatal("context deadline missing")
		}
		w.WriteHeader(http.StatusOK)
	}))

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

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

func TestRecoverHandlesPanic(t *testing.T) {
	logger := slog.New(slog.NewTextHandler(io.Discard, nil))
	handler := Recover(logger)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		panic("boom")
	}))

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

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

func TestAccessLogUsesForwardedClientIP(t *testing.T) {
	var buf bytes.Buffer
	logger := slog.New(slog.NewTextHandler(&buf, nil))
	handler := AccessLog(logger)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusNoContent)
	}))

	req := httptest.NewRequest(http.MethodGet, "/mcp", nil)
	req.RemoteAddr = "10.0.0.10:1234"
	req.Header.Set("X-Real-IP", "203.0.113.7")
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	if rec.Code != http.StatusNoContent {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusNoContent)
	}
	if !strings.Contains(buf.String(), "remote_addr=203.0.113.7") {
		t.Fatalf("log output = %q, want remote_addr=203.0.113.7", buf.String())
	}
}

func TestAccessLogIncludesMCPToolName(t *testing.T) {
	var buf bytes.Buffer
	logger := slog.New(slog.NewTextHandler(&buf, nil))
	handler := AccessLog(logger)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusNoContent)
	}))

	payload := map[string]any{
		"jsonrpc": "2.0",
		"id":      "1",
		"method":  "tools/call",
		"params": map[string]any{
			"name":      "list_projects",
			"arguments": map[string]any{},
		},
	}
	body, err := json.Marshal(payload)
	if err != nil {
		t.Fatalf("json.Marshal() error = %v", err)
	}

	req := httptest.NewRequest(http.MethodPost, "/mcp", bytes.NewReader(body))
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	if rec.Code != http.StatusNoContent {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusNoContent)
	}
	if !strings.Contains(buf.String(), "tool=list_projects") {
		t.Fatalf("log output = %q, want tool=list_projects", buf.String())
	}
	if !strings.Contains(buf.String(), "tool_call=list_projects") {
		t.Fatalf("log output = %q, want tool_call=list_projects", buf.String())
	}
}

func TestAccessLogIncludesMCPSessionIDHeader(t *testing.T) {
	var buf bytes.Buffer
	logger := slog.New(slog.NewTextHandler(&buf, nil))
	handler := AccessLog(logger)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusNoContent)
	}))

	req := httptest.NewRequest(http.MethodGet, "/sse", nil)
	req.Header.Set("MCP-Session-Id", "sess-123")
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	if rec.Code != http.StatusNoContent {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusNoContent)
	}
	if !strings.Contains(buf.String(), "mcp_session_id=sess-123") {
		t.Fatalf("log output = %q, want mcp_session_id=sess-123", buf.String())
	}
}

func TestAccessLogIncludesMCPSessionIDQueryParam(t *testing.T) {
	var buf bytes.Buffer
	logger := slog.New(slog.NewTextHandler(&buf, nil))
	handler := AccessLog(logger)(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusNoContent)
	}))

	req := httptest.NewRequest(http.MethodGet, "/sse?session_id=sess-q-1", nil)
	rec := httptest.NewRecorder()
	handler.ServeHTTP(rec, req)

	if rec.Code != http.StatusNoContent {
		t.Fatalf("status = %d, want %d", rec.Code, http.StatusNoContent)
	}
	if !strings.Contains(buf.String(), "mcp_session_id=sess-q-1") {
		t.Fatalf("log output = %q, want mcp_session_id=sess-q-1", buf.String())
	}
}