package redis

import (
	"context"
	"encoding/json"
	"math/rand"
	"strings"
	"time"

	"github.com/pkg/errors"
	"github.com/redis/go-redis/v9"
	"gitlab.com/wpetit/goweb/logger"
)

var (
	DefaultTxMaxAttempts = 20
	DefaultTxBaseDelay   = 100 * time.Millisecond
)

type jsonWrapper[T any] struct {
	value T
}

func (w *jsonWrapper[T]) MarshalBinary() ([]byte, error) {
	data, err := json.Marshal(w.value)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	return data, nil
}

func (w *jsonWrapper[T]) UnmarshalBinary(data []byte) error {
	if err := json.Unmarshal(data, &w.value); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

func (w *jsonWrapper[T]) UnmarshalText(data []byte) error {
	if err := json.Unmarshal(data, &w.value); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

func (w *jsonWrapper[T]) Value() T {
	return w.value
}

func wrap[T any](v T) *jsonWrapper[T] {
	return &jsonWrapper[T]{v}
}

func unwrap[T any](v any) (T, error) {
	str, ok := v.(string)
	if !ok {
		return *new(T), errors.Errorf("could not unwrap value of type '%T'", v)
	}

	u := new(T)

	if err := json.Unmarshal([]byte(str), u); err != nil {
		return *new(T), errors.WithStack(err)
	}

	return *u, nil
}

func key(parts ...string) string {
	return strings.Join(parts, ":")
}

func WithRetry(ctx context.Context, client redis.UniversalClient, key string, fn func(ctx context.Context, tx *redis.Tx) error, maxAttempts int, baseDelay time.Duration) error {
	var err error

	delay := baseDelay

	for attempt := 0; attempt < maxAttempts; attempt++ {
		if err = WithTx(ctx, client, key, fn); err != nil {
			err = errors.WithStack(err)
			logger.Debug(ctx, "redis transaction failed", logger.E(err))

			if errors.Is(err, redis.TxFailedErr) {
				logger.Debug(ctx, "retrying redis transaction", logger.F("attempts", attempt), logger.F("delay", delay))
				time.Sleep(delay)
				delay = delay*2 + time.Duration(rand.Int63n(int64(baseDelay)))

				continue
			}

			return errors.WithStack(err)
		}

		return nil
	}

	logger.Error(ctx, "redis error", logger.E(errors.WithStack(err)))

	return errors.WithStack(redis.TxFailedErr)
}

func WithTx(ctx context.Context, client redis.UniversalClient, key string, fn func(ctx context.Context, tx *redis.Tx) error) error {
	txf := func(tx *redis.Tx) error {
		if err := fn(ctx, tx); err != nil {
			return errors.WithStack(err)
		}

		return nil
	}

	err := client.Watch(ctx, txf, key)
	if err != nil {
		return errors.WithStack(err)
	}

	return nil
}

func contains[T ~string](values []T, v T) bool {
	for _, vv := range values {
		if vv == v {
			return true
		}
	}

	return false
}