package health

import (
	"encoding/json"
	"errors"
	"net/http"
	"net/http/httptest"
	"testing"
)

func TestHealthHandler_ServeHTTP(t *testing.T) {
	tests := []struct {
		name           string
		method         string
		checkers       []HealthChecker
		expectedStatus int
		expectedHealth string
	}{
		{
			name:           "GET request with no checkers",
			method:         "GET",
			checkers:       []HealthChecker{},
			expectedStatus: http.StatusOK,
			expectedHealth: "ok",
		},
		{
			name:   "GET request with healthy checker",
			method: "GET",
			checkers: []HealthChecker{
				NewSimpleChecker("test", func() error { return nil }),
			},
			expectedStatus: http.StatusOK,
			expectedHealth: "ok",
		},
		{
			name:   "GET request with unhealthy checker",
			method: "GET",
			checkers: []HealthChecker{
				NewSimpleChecker("test", func() error { return errors.New("test error") }),
			},
			expectedStatus: http.StatusServiceUnavailable,
			expectedHealth: "error",
		},
		{
			name:           "POST request should return 405",
			method:         "POST",
			checkers:       []HealthChecker{},
			expectedStatus: http.StatusMethodNotAllowed,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			handler := NewHandler("1.0.0")
			for _, checker := range tt.checkers {
				handler.AddCheck(checker)
			}

			req := httptest.NewRequest(tt.method, "/health", nil)
			w := httptest.NewRecorder()

			handler.ServeHTTP(w, req)

			if w.Code != tt.expectedStatus {
				t.Errorf("expected status %d, got %d", tt.expectedStatus, w.Code)
			}

			if tt.method == "GET" && tt.expectedStatus != http.StatusMethodNotAllowed {
				var response Response
				if err := json.NewDecoder(w.Body).Decode(&response); err != nil {
					t.Fatalf("failed to decode response: %v", err)
				}

				if response.Status != tt.expectedHealth {
					t.Errorf("expected status %s, got %s", tt.expectedHealth, response.Status)
				}

				if response.Version != "1.0.0" {
					t.Errorf("expected version 1.0.0, got %s", response.Version)
				}

				if len(response.Checks) != len(tt.checkers) {
					t.Errorf("expected %d checks, got %d", len(tt.checkers), len(response.Checks))
				}
			}
		})
	}
}

func TestSimpleChecker(t *testing.T) {
	t.Run("healthy checker", func(t *testing.T) {
		checker := NewSimpleChecker("test", func() error { return nil })
		
		if checker.Name() != "test" {
			t.Errorf("expected name 'test', got %s", checker.Name())
		}
		
		if err := checker.Check(); err != nil {
			t.Errorf("expected no error, got %v", err)
		}
	})

	t.Run("unhealthy checker", func(t *testing.T) {
		testErr := errors.New("test error")
		checker := NewSimpleChecker("test", func() error { return testErr })
		
		if checker.Name() != "test" {
			t.Errorf("expected name 'test', got %s", checker.Name())
		}
		
		if err := checker.Check(); err != testErr {
			t.Errorf("expected error %v, got %v", testErr, err)
		}
	})
}