package subscription

import (
	"errors"
	"fmt"
	"maps"
	"strings"
	"testing"
	"text/template"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"github.com/thrasher-corp/gocryptotrader/common"
	"github.com/thrasher-corp/gocryptotrader/currency"
	"github.com/thrasher-corp/gocryptotrader/exchanges/asset"
)

var errValidateSubscriptionsTestError = errors.New("validate subscriptions test error")

type mockExWithSubValidator struct {
	GenerateBadSubscription bool
	FailGetSubscriptions    bool
	*mockEx
}

func (m *mockExWithSubValidator) ValidateSubscriptions(in List) error {
	for _, sub := range in {
		if sub.Channel == "fail-channel" {
			return fmt.Errorf("%w: %q", errValidateSubscriptionsTestError, sub.String())
		}
	}
	return nil
}

func (m *mockExWithSubValidator) GetSubscriptions() (List, error) {
	if m.GenerateBadSubscription {
		return List{{Channel: "fail-channel"}}, nil
	}
	if m.FailGetSubscriptions {
		return nil, ErrNotFound
	}
	return nil, nil
}

type mockEx struct {
	pairs     assetPairs
	assets    asset.Items
	tpl       string
	auth      bool
	errPairs  error
	errFormat error
}

func newMockEx() *mockEx {
	return &mockEx{
		assets: asset.Items{asset.Spot, asset.Futures, asset.Index},
		pairs: assetPairs{
			asset.Spot:    currency.Pairs{ethusdcPair, btcusdtPair, currency.NewPair(currency.LTC, currency.USDT)},
			asset.Futures: currency.Pairs{ethusdcPair, btcusdtPair},
			asset.Index:   currency.Pairs{btcusdtPair},
		},
	}
}

func (m *mockEx) IsAssetWebsocketSupported(a asset.Item) bool {
	return a != asset.Index
}

func (m *mockEx) GetEnabledPairs(a asset.Item) (currency.Pairs, error) {
	return m.pairs[a], m.errPairs
}

func (m *mockEx) GetPairFormat(_ asset.Item, _ bool) (currency.PairFormat, error) {
	return currency.PairFormat{Uppercase: true, Delimiter: "-"}, m.errFormat
}

func (m *mockEx) GetSubscriptionTemplate(s *Subscription) (*template.Template, error) {
	if s.Channel == "nil" {
		return nil, nil
	}
	return template.New(m.tpl).
		Funcs(template.FuncMap{
			"assetName": func(a asset.Item) string {
				if a == asset.Futures {
					return "future"
				}
				return a.String()
			},
			"updateAssetPairs": func(ap assetPairs) string {
				ap[asset.Futures] = nil
				ap[asset.Spot] = ap[asset.Spot][0:1]
				return ""
			},
			"batch": func(pairs currency.Pairs, size int) []string {
				s := []string{}
				for _, p := range common.Batch(pairs, size) {
					p = p.Format(currency.PairFormat{Uppercase: true})
					s = append(s, p.Join())
				}
				return s
			},
		}).
		ParseFiles("testdata/" + m.tpl)
}

func (m *mockEx) GetAssetTypes(_ bool) asset.Items            { return m.assets }
func (m *mockEx) CanUseAuthenticatedWebsocketEndpoints() bool { return m.auth }
func (m *mockEx) GetSubscriptions() (List, error)             { return nil, nil }

// equalLists is a utility function to compare subscription lists and show a pretty failure message
// It overcomes the verbose depth of assert.ElementsMatch spewConfig
// Duplicate of internal/testing/subscriptions/EqualLists
func equalLists(tb testing.TB, a, b List) bool {
	tb.Helper()
	for _, sub := range append(a, b...) {
		sub.Key = &StrictKey{&ExactKey{sub}}
	}
	s, err := NewStoreFromList(a)
	require.NoError(tb, err, "NewStoreFromList must not error")
	added, missing := s.Diff(b)
	if len(added) > 0 || len(missing) > 0 {
		fail := "Differences:"
		if len(added) > 0 {
			fail = fail + "\n + " + strings.Join(added.Strings(), "\n + ")
		}
		if len(missing) > 0 {
			fail = fail + "\n - " + strings.Join(missing.Strings(), "\n - ")
		}
		assert.Fail(tb, fail, "Subscriptions should be equal")
		return false
	}
	return true
}

// StrictKey is key type for subscriptions where all the pairs, QualifiedChannel and Params in a Subscription must match exactly
type StrictKey struct {
	*ExactKey
}

var _ MatchableKey = StrictKey{} // Enforce StrictKey must implement MatchableKey

// Match implements MatchableKey
// Returns true if the key fields exactly matches the subscription, including all Pairs, QualifiedChannel and Params
func (k StrictKey) Match(eachKey MatchableKey) bool {
	if !k.ExactKey.Match(eachKey) {
		return false
	}
	eachSub := eachKey.GetSubscription()
	return eachSub.QualifiedChannel == k.QualifiedChannel &&
		maps.Equal(eachSub.Params, k.Params)
}

// String implements Stringer; returns the Asset, Channel and Pairs
// Does not provide concurrency protection on the subscription it points to
func (k StrictKey) String() string {
	s := k.Subscription
	if s == nil {
		return "Uninitialised StrictKey"
	}
	return s.QualifiedChannel + " " + ExactKey{s}.String()
}