first commit

provider/json/provider.go

@@ -0,0 +1,66 @@
+package json
+
+import (
+	"context"
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+
+	"github.com/tidwall/gjson"
+	"gitoa.ru/go-4devs/config"
+	"gitoa.ru/go-4devs/config/key"
+	"gitoa.ru/go-4devs/config/value"
+)
+
+var _ config.Provider = (*Provider)(nil)
+
+func New(json []byte, opts ...Option) *Provider {
+	provider := Provider{
+		key:  key.Name,
+		data: json,
+	}
+
+	for _, opt := range opts {
+		opt(&provider)
+	}
+
+	return &provider
+}
+
+func NewFile(path string, opts ...Option) (*Provider, error) {
+	file, err := ioutil.ReadFile(filepath.Clean(path))
+	if err != nil {
+		return nil, fmt.Errorf("%w: unable to read config file %#q: file not found or unreadable", err, path)
+	}
+
+	return New(file), nil
+}
+
+type Option func(*Provider)
+
+type Provider struct {
+	data []byte
+	key  config.KeyFactory
+}
+
+func (p *Provider) IsSupport(ctx context.Context, key config.Key) bool {
+	return p.key(ctx, key) != ""
+}
+
+func (p *Provider) Name() string {
+	return "json"
+}
+
+func (p *Provider) Read(ctx context.Context, key config.Key) (config.Variable, error) {
+	path := p.key(ctx, key)
+
+	if val := gjson.GetBytes(p.data, path); val.Exists() {
+		return config.Variable{
+			Name:     path,
+			Provider: p.Name(),
+			Value:    value.JString(val.String()),
+		}, nil
+	}
+
+	return config.Variable{}, config.ErrVariableNotFound
+}