package redis

import (
	"context"
	"time"

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

const (
	keyPrefixProxy = "proxy"
)

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

// GetProxy implements store.ProxyRepository
func (r *ProxyRepository) GetProxy(ctx context.Context, name store.ProxyName) (*store.Proxy, error) {
	key := proxyKey(name)
	var proxyItem *proxyItem

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

		proxyItem = pItem

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

	proxy, err := proxyItem.ToProxy()
	if err != nil {
		return nil, errors.WithStack(err)
	}

	return proxy, nil
}

func (r *ProxyRepository) txGetProxyItem(ctx context.Context, tx *redis.Tx, name store.ProxyName) (*proxyItem, error) {
	proxyItem := proxyItem{}
	key := proxyKey(name)

	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(&proxyItem.proxyHeaderItem); err != nil {
		return nil, errors.WithStack(err)
	}

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

	return &proxyItem, nil
}

// CreateProxy implements store.ProxyRepository
func (r *ProxyRepository) CreateProxy(ctx context.Context, name store.ProxyName, to string, from ...string) (*store.Proxy, error) {
	now := time.Now().UTC()
	key := proxyKey(name)

	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)
		}

		proxyItem := &proxyItem{
			proxyHeaderItem: proxyHeaderItem{
				Name:      string(name),
				CreatedAt: wrap(now),
				UpdatedAt: wrap(now),
				Weight:    0,
				Revision:  0,
				Enabled:   false,
			},
			To:   to,
			From: wrap(from),
		}

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

			return nil
		})

		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.Proxy{
		ProxyHeader: store.ProxyHeader{
			Name: name,

			Weight:  0,
			Enabled: false,
		},
		To:        to,
		From:      from,
		CreatedAt: now,
		UpdatedAt: now,
	}, nil
}

// DeleteProxy implements store.ProxyRepository
func (r *ProxyRepository) DeleteProxy(ctx context.Context, name store.ProxyName) error {
	key := proxyKey(name)

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

	return nil
}

// QueryProxy implements store.ProxyRepository
func (r *ProxyRepository) QueryProxy(ctx context.Context, funcs ...store.QueryProxyOptionFunc) ([]*store.ProxyHeader, error) {
	opts := store.DefaultQueryProxyOptions()
	for _, fn := range funcs {
		fn(opts)
	}

	iter := r.client.Scan(ctx, 0, keyPrefixProxy+"*", 0).Iterator()

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

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

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

		proxyHeader, err := proxyHeaderItem.ToProxyHeader()
		if err != nil {
			return nil, errors.WithStack(err)
		}

		if opts.Enabled != nil && proxyHeader.Enabled != *opts.Enabled {
			continue
		}

		if opts.Names != nil && !contains(opts.Names, proxyHeader.Name) {
			continue
		}

		headers = append(headers, proxyHeader)
	}

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

	return headers, nil
}

// UpdateProxy implements store.ProxyRepository
func (r *ProxyRepository) UpdateProxy(ctx context.Context, name store.ProxyName, funcs ...store.UpdateProxyOptionFunc) (*store.Proxy, error) {
	opts := &store.UpdateProxyOptions{}
	for _, fn := range funcs {
		fn(opts)
	}

	key := proxyKey(name)
	var proxyItem proxyItem

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

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

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

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

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

		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.proxyHeaderItem)
			p.HMSet(ctx, key, item)

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

		proxyItem = *item

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

	proxy, err := proxyItem.ToProxy()
	if err != nil {
		return nil, errors.WithStack(err)
	}

	return proxy, nil
}

func NewProxyRepository(client redis.UniversalClient, txMaxAttempts int, txRetryBaseDelay time.Duration) *ProxyRepository {
	return &ProxyRepository{
		client:           client,
		txMaxAttempts:    20,
		txRetryBaseDelay: txRetryBaseDelay,
	}
}

var _ store.ProxyRepository = &ProxyRepository{}

func proxyKey(name store.ProxyName) string {
	return key(keyPrefixProxy, string(name))
}