Tidy up loader code a little and make more generic

We weren't using some of this anyway and we could easily just load any
file into an object - so lets use it for catalog as well as the config
file.

cmd/tap-incident/cmd/app.go

@@ -137,7 +137,7 @@ func loadCatalogOrError(ctx context.Context, catalogFile string) (catalog *tap.C
 		OUT("Failed to load catalog file!\n")
 	}()
 
-	catalog, err = tap.CatalogFileLoader(catalogFile).Load(ctx)
+	catalog, err = config.LoadAndParse(catalogFile, tap.Catalog{})
 	if err != nil {
 		return nil, errors.Wrap(err, "loading catalog")
 	}
@@ -167,7 +167,7 @@ func loadConfigOrError(ctx context.Context, configFile string) (cfg *config.Conf
 		return nil, errors.New("No config file set! (--config)")
 	}
 
-	cfg, err = config.FileLoader(configFile).Load(ctx)
+	cfg, err = config.LoadAndParse(configFile, config.Config{})
 	if err != nil {
 		return nil, errors.Wrap(err, "loading config")
 	}

config/config.go

@@ -1,8 +1,6 @@
 package config
 
 import (
-	"context"
-
 	validation "github.com/go-ozzo/ozzo-validation"
 )
 
@@ -17,8 +15,3 @@ func (c Config) Validate() error {
 			Error("must provide an api_key to authenticate against the incident.io API.")),
 	)
 }
-
-// Load returns currently loaded config
-func (c Config) Load(context.Context) (Config, error) {
-	return Config(c), nil
-}

config/loader.go

@@ -1,28 +1,24 @@
 package config
 
 import (
-	"context"
+	"encoding/json"
 	"os"
-)
 
-type Loader interface {
-	Load(context.Context) (*Config, error)
-}
+	"github.com/pkg/errors"
+)
 
-type LoaderFunc func(context.Context) (*Config, error)
+func LoadAndParse[T any](path string, obj T) (*T, error) {
+	b, err := os.ReadFile(path)
+	if err != nil {
+		return &obj, errors.Wrapf(err, "unable to read file at path %v", path)
+	}
 
-func (l LoaderFunc) Load(ctx context.Context) (*Config, error) {
-	return l(ctx)
+	return ParseContents(b, obj)
 }
 
-// FileLoader loads config from a filepath
-type FileLoader string
-
-func (l FileLoader) Load(context.Context) (*Config, error) {
-	data, err := os.ReadFile(string(l))
-	if err != nil {
-		return nil, err
+func ParseContents[T any](content []byte, obj T) (*T, error) {
+	if err := json.Unmarshal(content, &obj); err != nil {
+		return &obj, err
 	}
-
-	return Parse(string(l), data)
+	return &obj, nil
 }

tap/catalog.go

@@ -1,12 +1,7 @@
 package tap
 
 import (
-	"context"
-	"encoding/json"
-	"os"
-
 	"github.com/incident-io/singer-tap/model"
-	"github.com/pkg/errors"
 )
 
 // A catalog can contain several streams or "entries"
@@ -84,34 +79,3 @@ func NewDefaultCatalog(streams map[string]Stream) *Catalog {
 		Streams: entries,
 	}
 }
-
-type CatalogLoader interface {
-	Load(context.Context) (*Catalog, error)
-}
-
-type CatalogLoaderFunc func(context.Context) (*Catalog, error)
-
-func (l CatalogLoaderFunc) Load(ctx context.Context) (*Catalog, error) {
-	return l(ctx)
-}
-
-// CatalogFileLoader loads Catalog from a filepath
-type CatalogFileLoader string
-
-func (l CatalogFileLoader) Load(context.Context) (*Catalog, error) {
-	data, err := os.ReadFile(string(l))
-	if err != nil {
-		return nil, err
-	}
-
-	return ParseCatalogFile(string(l), data)
-}
-
-func ParseCatalogFile(filename string, data []byte) (*Catalog, error) {
-	var catalog Catalog
-	if err := json.Unmarshal(data, &catalog); err != nil {
-		return nil, errors.Wrap(err, "parsing json")
-	}
-
-	return &catalog, nil
-}