package redis

import (
	"context"
	"time"

	"forge.cadoles.com/cadoles/bouncer/internal/store"
	"github.com/pkg/errors"
	"github.com/redis/go-redis/v9"
)

const (
	keyPrefixLayer = "layer"
)

type LayerRepository struct {
	client           redis.UniversalClient
	txMaxAttempts    int
	txRetryBaseDelay time.Duration
}

// CreateLayer implements store.LayerRepository
func (r *LayerRepository) CreateLayer(ctx context.Context, proxyName store.ProxyName, layerName store.LayerName, layerType store.LayerType, options store.LayerOptions) (*store.Layer, error) {
	now := time.Now().UTC()
	key := layerKey(proxyName, layerName)

	layerItem := &layerItem{
		layerHeaderItem: layerHeaderItem{
			Proxy:    string(proxyName),
			Name:     string(layerName),
			Type:     string(layerType),
			Weight:   0,
			Revision: 0,
			Enabled:  false,
		},

		CreatedAt: wrap(now),
		UpdatedAt: wrap(now),
		Options:   wrap(options),
	}

	txf := func(tx *redis.Tx) error {
		exists, err := tx.Exists(ctx, key).Uint64()
		if err != nil {
			return errors.WithStack(err)
		}

		if exists > 0 {
			return errors.WithStack(store.ErrAlreadyExist)
		}

		_, err = tx.TxPipelined(ctx, func(p redis.Pipeliner) error {
			p.HMSet(ctx, key, &layerItem.layerHeaderItem)
			p.HMSet(ctx, key, layerItem)

			return nil
		})

		if err != nil {
			return errors.WithStack(err)
		}

		layerItem, err = r.txGetLayerItem(ctx, tx, proxyName, layerName)
		if err != nil {
			return errors.WithStack(err)
		}

		return nil
	}

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

	return &store.Layer{
		LayerHeader: store.LayerHeader{
			Name:    store.LayerName(layerItem.Name),
			Proxy:   store.ProxyName(layerItem.Proxy),
			Type:    store.LayerType(layerItem.Type),
			Weight:  layerItem.Weight,
			Enabled: layerItem.Enabled,
		},

		CreatedAt: layerItem.CreatedAt.Value(),
		UpdatedAt: layerItem.UpdatedAt.Value(),
		Options:   layerItem.Options.Value(),
	}, nil
}

// DeleteLayer implements store.LayerRepository
func (r *LayerRepository) DeleteLayer(ctx context.Context, proxyName store.ProxyName, layerName store.LayerName) error {
	key := layerKey(proxyName, layerName)

	if cmd := r.client.Del(ctx, key); cmd.Err() != nil {
		return errors.WithStack(cmd.Err())
	}

	return nil
}

// GetLayer implements store.LayerRepository
func (r *LayerRepository) GetLayer(ctx context.Context, proxyName store.ProxyName, layerName store.LayerName) (*store.Layer, error) {
	key := layerKey(proxyName, layerName)
	var layerItem *layerItem

	err := WithRetry(ctx, r.client, key, func(ctx context.Context, tx *redis.Tx) error {
		pItem, err := r.txGetLayerItem(ctx, tx, proxyName, layerName)
		if err != nil {
			return errors.WithStack(err)
		}

		layerItem = pItem

		return nil
	}, r.txMaxAttempts, r.txRetryBaseDelay)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	layer, err := layerItem.ToLayer()
	if err != nil {
		return nil, errors.WithStack(err)
	}

	return layer, nil
}

func (r *LayerRepository) txGetLayerItem(ctx context.Context, tx *redis.Tx, proxyName store.ProxyName, layerName store.LayerName) (*layerItem, error) {
	layerItem := layerItem{}
	key := layerKey(proxyName, layerName)

	exists, err := tx.Exists(ctx, key).Uint64()
	if err != nil {
		return nil, errors.WithStack(err)
	}

	if exists == 0 {
		return nil, errors.WithStack(store.ErrNotFound)
	}

	if err := tx.HGetAll(ctx, key).Scan(&layerItem.layerHeaderItem); err != nil {
		return nil, errors.WithStack(err)
	}

	if err := tx.HGetAll(ctx, key).Scan(&layerItem); err != nil {
		return nil, errors.WithStack(err)
	}

	return &layerItem, nil
}

// QueryLayers implements store.LayerRepository
func (r *LayerRepository) QueryLayers(ctx context.Context, proxyName store.ProxyName, funcs ...store.QueryLayerOptionFunc) ([]*store.LayerHeader, error) {
	opts := store.DefaultQueryLayerOptions()
	for _, fn := range funcs {
		fn(opts)
	}

	keyParts := []string{keyPrefixLayer, string(proxyName)}

	if opts.Name != nil {
		keyParts = append(keyParts, string(*opts.Name))
	} else {
		keyParts = append(keyParts, "*")
	}

	key := key(keyParts...)

	iter := r.client.Scan(ctx, 0, key, 0).Iterator()

	headers := make([]*store.LayerHeader, 0)

	for iter.Next(ctx) {
		key := iter.Val()

		layerHeaderItem := &layerHeaderItem{}

		if err := r.client.HGetAll(ctx, key).Scan(layerHeaderItem); err != nil {
			return nil, errors.WithStack(err)
		}

		layerHeader, err := layerHeaderItem.ToLayerHeader()
		if err != nil {
			return nil, errors.WithStack(err)
		}

		headers = append(headers, layerHeader)
	}

	if err := iter.Err(); err != nil {
		return nil, errors.WithStack(err)
	}

	return headers, nil
}

// UpdateLayer implements store.LayerRepository
func (r *LayerRepository) UpdateLayer(ctx context.Context, proxyName store.ProxyName, layerName store.LayerName, funcs ...store.UpdateLayerOptionFunc) (*store.Layer, error) {
	opts := &store.UpdateLayerOptions{}
	for _, fn := range funcs {
		fn(opts)
	}

	key := layerKey(proxyName, layerName)
	var layerItem layerItem

	err := WithRetry(ctx, r.client, key, func(ctx context.Context, tx *redis.Tx) error {
		item, err := r.txGetLayerItem(ctx, tx, proxyName, layerName)
		if err != nil {
			return errors.WithStack(err)
		}

		if opts.Enabled != nil {
			item.Enabled = *opts.Enabled
		}

		if opts.Weight != nil {
			item.Weight = *opts.Weight
		}

		if opts.Options != nil {
			item.Options = wrap(*opts.Options)
		}

		item.UpdatedAt = wrap(time.Now().UTC())
		item.Revision = item.Revision + 1

		_, err = tx.TxPipelined(ctx, func(p redis.Pipeliner) error {
			p.HMSet(ctx, key, item.layerHeaderItem)
			p.HMSet(ctx, key, item)

			return nil
		})
		if err != nil {
			return errors.WithStack(err)
		}

		layerItem = *item

		return nil
	}, r.txMaxAttempts, r.txRetryBaseDelay)
	if err != nil {
		return nil, errors.WithStack(err)
	}

	layer, err := layerItem.ToLayer()
	if err != nil {
		return nil, errors.WithStack(err)
	}

	return layer, nil
}

func NewLayerRepository(client redis.UniversalClient, txMaxAttempts int, txRetryBaseDelay time.Duration) *LayerRepository {
	return &LayerRepository{
		client:           client,
		txMaxAttempts:    txMaxAttempts,
		txRetryBaseDelay: txRetryBaseDelay,
	}
}

var _ store.LayerRepository = &LayerRepository{}

func layerKey(proxyName store.ProxyName, layerName store.LayerName) string {
	return key(keyPrefixLayer, string(proxyName), string(layerName))
}