package registry

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"net/http/httptest"
	"testing"
	"time"

	"github.com/beckn-one/beckn-onix/pkg/model"
)

// TestValidate ensures the config validation logic works correctly.
func TestValidate(t *testing.T) {
	t.Parallel()
	testCases := []struct {
		name        string
		config      *Config
		expectedErr string
	}{
		{
			name:        "should return error for nil config",
			config:      nil,
			expectedErr: "registry config cannot be nil",
		},
		{
			name:        "should return error for empty URL",
			config:      &Config{URL: ""},
			expectedErr: "registry URL cannot be empty",
		},
		{
			name:        "should succeed for valid config",
			config:      &Config{URL: "http://localhost:8080"},
			expectedErr: "",
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			err := validate(tc.config)
			if tc.expectedErr != "" {
				if err == nil {
					t.Fatalf("expected an error but got none")
				}
				if err.Error() != tc.expectedErr {
					t.Errorf("expected error message '%s', but got '%s'", tc.expectedErr, err.Error())
				}
			} else {
				if err != nil {
					t.Fatalf("expected no error, but got: %v", err)
				}
			}
		})
	}
}

// TestNew tests the constructor for the RegistryClient.
func TestNew(t *testing.T) {
	t.Parallel()

	t.Run("should fail with invalid config", func(t *testing.T) {
		_, _, err := New(context.Background(), &Config{URL: ""})
		if err == nil {
			t.Fatal("expected an error for invalid config but got none")
		}
	})

	t.Run("should succeed with valid config and set defaults", func(t *testing.T) {
		cfg := &Config{URL: "http://test.com"}
		client, closer, err := New(context.Background(), cfg)
		if err != nil {
			t.Fatalf("expected no error, but got: %v", err)
		}
		if client == nil {
			t.Fatal("expected client to be non-nil")
		}
		if closer == nil {
			t.Fatal("expected closer to be non-nil")
		}
		// Check if default retry settings are applied (go-retryablehttp defaults)
		if client.client.RetryMax != 4 {
			t.Errorf("expected default RetryMax of 4, but got %d", client.client.RetryMax)
		}
	})

	t.Run("should apply custom retry settings", func(t *testing.T) {
		cfg := &Config{
			URL:          "http://test.com",
			RetryMax:     10,
			RetryWaitMin: 100 * time.Millisecond,
			RetryWaitMax: 1 * time.Second,
		}
		client, _, err := New(context.Background(), cfg)
		if err != nil {
			t.Fatalf("expected no error, but got: %v", err)
		}

		if client.client.RetryMax != cfg.RetryMax {
			t.Errorf("expected RetryMax to be %d, but got %d", cfg.RetryMax, client.client.RetryMax)
		}
		if client.client.RetryWaitMin != cfg.RetryWaitMin {
			t.Errorf("expected RetryWaitMin to be %v, but got %v", cfg.RetryWaitMin, client.client.RetryWaitMin)
		}
		if client.client.RetryWaitMax != cfg.RetryWaitMax {
			t.Errorf("expected RetryWaitMax to be %v, but got %v", cfg.RetryWaitMax, client.client.RetryWaitMax)
		}
	})
}

// TestRegistryClient_Lookup tests the Lookup method.
func TestRegistryClient_Lookup(t *testing.T) {
	t.Parallel()

	t.Run("should succeed and unmarshal response", func(t *testing.T) {
		expectedSubs := []model.Subscription{
			{
				KeyID:            "test-key",
				SigningPublicKey: "test-signing-key",
				EncrPublicKey:    "test-encryption-key",
				ValidFrom:        time.Now(),
				ValidUntil:       time.Now().Add(24 * time.Hour),
				Status:           "SUBSCRIBED",
			},
			{
				KeyID:            "test-key-2",
				SigningPublicKey: "test-signing-key-2",
				EncrPublicKey:    "test-encryption-key-2",
				ValidFrom:        time.Now(),
				ValidUntil:       time.Now().Add(48 * time.Hour),
				Status:           "SUBSCRIBED",
			},
		}

		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			if r.URL.Path != "/lookup" {
				t.Errorf("expected path '/lookup', got '%s'", r.URL.Path)
			}
			w.Header().Set("Content-Type", "application/json")
			w.WriteHeader(http.StatusOK)
			if err := json.NewEncoder(w).Encode(expectedSubs); err != nil {
				t.Fatalf("failed to write response: %v", err)
			}
		}))
		defer server.Close()

		client, closer, err := New(context.Background(), &Config{URL: server.URL})
		if err != nil {
			t.Fatalf("failed to create client: %v", err)
		}
		defer closer()

		results, err := client.Lookup(context.Background(), &model.Subscription{})
		if err != nil {
			t.Fatalf("lookup failed: %v", err)
		}

		if len(results) != len(expectedSubs) {
			t.Fatalf("expected %d results, but got %d", len(expectedSubs), len(results))
		}

		if results[0].SubscriberID != expectedSubs[0].SubscriberID {
			t.Errorf("expected subscriber ID '%s', got '%s'", expectedSubs[0].SubscriberID, results[0].SubscriberID)
		}
	})

	t.Run("should fail on non-200 status", func(t *testing.T) {
		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			w.WriteHeader(http.StatusBadRequest)
		}))
		defer server.Close()

		client, closer, err := New(context.Background(), &Config{URL: server.URL})
		if err != nil {
			t.Fatalf("failed to create client: %v", err)
		}
		defer closer()

		_, err = client.Lookup(context.Background(), &model.Subscription{})
		if err == nil {
			t.Fatal("expected an error but got none")
		}
	})

	t.Run("should fail on bad JSON response", func(t *testing.T) {
		server := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			w.WriteHeader(http.StatusOK)
			fmt.Fprint(w, `[{"subscriber_id": "bad-json"`) // Malformed JSON
		}))
		defer server.Close()

		client, closer, err := New(context.Background(), &Config{URL: server.URL, RetryMax: 1})
		if err != nil {
			t.Fatalf("failed to create client: %v", err)
		}
		defer closer()

		_, err = client.Lookup(context.Background(), &model.Subscription{})
		if err == nil {
			t.Fatal("expected an unmarshaling error but got none")
		}
	})
}