package http

import (
	"context"
	"fmt"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	ptypes "github.com/traefik/paerser/types"
	"github.com/traefik/traefik/v3/pkg/config/dynamic"
	"github.com/traefik/traefik/v3/pkg/safe"
	"github.com/traefik/traefik/v3/pkg/tls"
)

func TestProvider_Init(t *testing.T) {
	tests := []struct {
		desc         string
		endpoint     string
		pollInterval ptypes.Duration
		expErr       bool
	}{
		{
			desc:   "should return an error if no endpoint is configured",
			expErr: true,
		},
		{
			desc:     "should return an error if pollInterval is equal to 0",
			endpoint: "http://localhost:8080",
			expErr:   true,
		},
		{
			desc:         "should not return an error",
			endpoint:     "http://localhost:8080",
			pollInterval: ptypes.Duration(time.Second),
			expErr:       false,
		},
	}

	for _, test := range tests {
		t.Run(test.desc, func(t *testing.T) {
			provider := &Provider{
				Endpoint:     test.endpoint,
				PollInterval: test.pollInterval,
			}

			err := provider.Init()
			if test.expErr {
				require.Error(t, err)
				return
			}

			require.NoError(t, err)
		})
	}
}

func TestProvider_SetDefaults(t *testing.T) {
	provider := &Provider{}

	provider.SetDefaults()

	assert.Equal(t, provider.PollInterval, ptypes.Duration(5*time.Second))
	assert.Equal(t, provider.PollTimeout, ptypes.Duration(5*time.Second))
}

func TestProvider_fetchConfigurationData(t *testing.T) {
	tests := []struct {
		desc       string
		statusCode int
		headers    map[string]string
		expData    []byte
		expErr     require.ErrorAssertionFunc
	}{
		{
			desc:       "should return the fetched configuration data",
			statusCode: http.StatusOK,
			expData:    []byte("{}"),
			expErr:     require.NoError,
		},
		{
			desc:       "should send configured headers",
			statusCode: http.StatusOK,
			headers: map[string]string{
				"Foo":  "bar",
				"Bar":  "baz",
				"Host": "localhost",
			},
			expData: []byte("{}"),
			expErr:  require.NoError,
		},
		{
			desc:       "should return an error if endpoint does not return an OK status code",
			statusCode: http.StatusInternalServerError,
			expErr:     require.Error,
		},
	}

	for _, test := range tests {
		t.Run(test.desc, func(t *testing.T) {
			handlerCalled := false
			srv := httptest.NewServer(http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {
				handlerCalled = true

				for k, v := range test.headers {
					if strings.EqualFold(k, "Host") {
						assert.Equal(t, v, req.Host)
					} else {
						assert.Equal(t, v, req.Header.Get(k))
					}
				}

				rw.WriteHeader(test.statusCode)
				_, _ = rw.Write([]byte("{}"))
			}))
			defer srv.Close()

			provider := Provider{
				Endpoint:     srv.URL,
				Headers:      test.headers,
				PollInterval: ptypes.Duration(1 * time.Second),
				PollTimeout:  ptypes.Duration(1 * time.Second),
			}

			err := provider.Init()
			require.NoError(t, err)

			configData, err := provider.fetchConfigurationData()
			test.expErr(t, err)

			assert.True(t, handlerCalled)
			assert.Equal(t, test.expData, configData)
		})
	}
}

func TestProvider_decodeConfiguration(t *testing.T) {
	tests := []struct {
		desc       string
		configData []byte
		expConfig  *dynamic.Configuration
		expErr     bool
	}{
		{
			desc:       "should return an error if the configuration data cannot be decoded",
			expErr:     true,
			configData: []byte("{"),
		},
		{
			desc:       "should return the decoded dynamic configuration",
			configData: []byte(`{"tcp":{"routers":{"foo":{}}}}`),
			expConfig: &dynamic.Configuration{
				HTTP: &dynamic.HTTPConfiguration{
					Routers:           make(map[string]*dynamic.Router),
					Middlewares:       make(map[string]*dynamic.Middleware),
					Services:          make(map[string]*dynamic.Service),
					ServersTransports: make(map[string]*dynamic.ServersTransport),
				},
				TCP: &dynamic.TCPConfiguration{
					Routers: map[string]*dynamic.TCPRouter{
						"foo": {},
					},
					Services:          make(map[string]*dynamic.TCPService),
					ServersTransports: map[string]*dynamic.TCPServersTransport{},
				},
				TLS: &dynamic.TLSConfiguration{
					Stores:  make(map[string]tls.Store),
					Options: make(map[string]tls.Options),
				},
				UDP: &dynamic.UDPConfiguration{
					Routers:  make(map[string]*dynamic.UDPRouter),
					Services: make(map[string]*dynamic.UDPService),
				},
			},
		},
	}

	for _, test := range tests {
		t.Run(test.desc, func(t *testing.T) {
			configuration, err := decodeConfiguration(test.configData)
			if test.expErr {
				require.Error(t, err)
				return
			}

			require.NoError(t, err)
			assert.Equal(t, test.expConfig, configuration)
		})
	}
}

func TestProvider_Provide(t *testing.T) {
	handler := func(rw http.ResponseWriter, req *http.Request) {
		rw.WriteHeader(http.StatusOK)
		_, _ = fmt.Fprintf(rw, "{}")
	}

	server := httptest.NewServer(http.HandlerFunc(handler))
	defer server.Close()

	provider := Provider{
		Endpoint:     server.URL,
		PollTimeout:  ptypes.Duration(1 * time.Second),
		PollInterval: ptypes.Duration(100 * time.Millisecond),
	}

	err := provider.Init()
	require.NoError(t, err)

	configurationChan := make(chan dynamic.Message)

	expConfiguration := &dynamic.Configuration{
		HTTP: &dynamic.HTTPConfiguration{
			Routers:           make(map[string]*dynamic.Router),
			Middlewares:       make(map[string]*dynamic.Middleware),
			Services:          make(map[string]*dynamic.Service),
			ServersTransports: make(map[string]*dynamic.ServersTransport),
		},
		TCP: &dynamic.TCPConfiguration{
			Routers:           make(map[string]*dynamic.TCPRouter),
			Services:          make(map[string]*dynamic.TCPService),
			ServersTransports: map[string]*dynamic.TCPServersTransport{},
		},
		TLS: &dynamic.TLSConfiguration{
			Stores:  make(map[string]tls.Store),
			Options: make(map[string]tls.Options),
		},
		UDP: &dynamic.UDPConfiguration{
			Routers:  make(map[string]*dynamic.UDPRouter),
			Services: make(map[string]*dynamic.UDPService),
		},
	}

	err = provider.Provide(configurationChan, safe.NewPool(context.Background()))
	require.NoError(t, err)

	timeout := time.After(time.Second)

	select {
	case configuration := <-configurationChan:
		assert.NotNil(t, configuration.Configuration)
		assert.Equal(t, expConfiguration, configuration.Configuration)
	case <-timeout:
		t.Errorf("timeout while waiting for config")
	}
}

func TestProvider_ProvideConfigurationOnlyOnceIfUnchanged(t *testing.T) {
	handler := func(rw http.ResponseWriter, req *http.Request) {
		rw.WriteHeader(http.StatusOK)
		_, _ = fmt.Fprintf(rw, "{}")
	}

	server := httptest.NewServer(http.HandlerFunc(handler))
	defer server.Close()

	provider := Provider{
		Endpoint:     server.URL + "/endpoint",
		PollTimeout:  ptypes.Duration(1 * time.Second),
		PollInterval: ptypes.Duration(100 * time.Millisecond),
	}

	err := provider.Init()
	require.NoError(t, err)

	configurationChan := make(chan dynamic.Message, 10)

	err = provider.Provide(configurationChan, safe.NewPool(context.Background()))
	require.NoError(t, err)

	time.Sleep(time.Second)

	assert.Len(t, configurationChan, 1)
}