add file and redis loader

internal/loader/redis.go

@@ -0,0 +1,124 @@
+package loader
+
+import (
+	"bytes"
+	"context"
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/go-redis/redis/v8"
+)
+
+const (
+	DefaultRedisKey = "gost"
+)
+
+type redisLoaderOptions struct {
+	db       int
+	password string
+	key      string
+}
+
+type RedisLoaderOption func(opts *redisLoaderOptions)
+
+func DBRedisLoaderOption(db int) RedisLoaderOption {
+	return func(opts *redisLoaderOptions) {
+		opts.db = db
+	}
+}
+
+func PasswordRedisLoaderOption(password string) RedisLoaderOption {
+	return func(opts *redisLoaderOptions) {
+		opts.password = password
+	}
+}
+
+func KeyRedisLoaderOption(key string) RedisLoaderOption {
+	return func(opts *redisLoaderOptions) {
+		opts.key = key
+	}
+}
+
+type redisSetLoader struct {
+	client *redis.Client
+	key    string
+}
+
+// RedisSetLoader loads values from redis set.
+func RedisSetLoader(addr string, opts ...RedisLoaderOption) Loader {
+	var options redisLoaderOptions
+	for _, opt := range opts {
+		opt(&options)
+	}
+
+	key := options.key
+	if key == "" {
+		key = DefaultRedisKey
+	}
+
+	return &redisSetLoader{
+		client: redis.NewClient(&redis.Options{
+			Addr:     addr,
+			Password: options.password,
+			DB:       options.db,
+		}),
+		key: key,
+	}
+}
+
+func (p *redisSetLoader) Load(ctx context.Context) (io.Reader, error) {
+	v, err := p.client.SMembers(ctx, p.key).Result()
+	if err != nil {
+		return nil, err
+	}
+	return bytes.NewReader([]byte(strings.Join(v, "\n"))), nil
+}
+
+func (p *redisSetLoader) Close() error {
+	return p.client.Close()
+}
+
+type redisHashLoader struct {
+	client *redis.Client
+	key    string
+}
+
+// RedisHashLoader loads values from redis hash.
+func RedisHashLoader(addr string, opts ...RedisLoaderOption) Loader {
+	var options redisLoaderOptions
+	for _, opt := range opts {
+		opt(&options)
+	}
+
+	key := options.key
+	if key == "" {
+		key = DefaultRedisKey
+	}
+
+	return &redisHashLoader{
+		client: redis.NewClient(&redis.Options{
+			Addr:     addr,
+			Password: options.password,
+			DB:       options.db,
+		}),
+		key: key,
+	}
+}
+
+func (p *redisHashLoader) Load(ctx context.Context) (io.Reader, error) {
+	m, err := p.client.HGetAll(ctx, p.key).Result()
+	if err != nil {
+		return nil, err
+	}
+
+	var b strings.Builder
+	for k, v := range m {
+		fmt.Fprintf(&b, "%s %s\n", k, v)
+	}
+	return bytes.NewBufferString(b.String()), nil
+}
+
+func (p *redisHashLoader) Close() error {
+	return p.client.Close()
+}