Add debug output (#29)

main.go

@@ -12,6 +12,7 @@ import (
 	"math/big"
 	"os"
 	"reflect"
+	"strconv"
 	"strings"
 	"time"
 
@@ -26,13 +27,16 @@ const (
 	optNameProjectID  = "project"
 	optNameDataset    = "dataset"
 	optNameOutputFile = "output"
+	optNameDebug      = "debug"
 	// envName
 	envNameGCloudProjectID = "GCLOUD_PROJECT_ID"
 	envNameBigQueryDataset = "BIGQUERY_DATASET"
 	envNameOutputFile      = "OUTPUT_FILE"
+	envNameDebug           = "DEBUG"
 	// defaultValue
 	defaultValueEmpty      = ""
 	defaultValueOutputFile = "bqschema.generated.go"
+	defaultValueDebug      = "false"
 )
 
 var (
@@ -75,6 +79,13 @@ func Run(ctx context.Context) (err error) {
 		return fmt.Errorf("getOptOrEnvOrDefault: %w", err)
 	}
 
+	var debugString string
+	debugString, err = getOptOrEnvOrDefault(optNameDebug, *optValueOutputPath, envNameDebug, defaultValueDebug)
+	if err != nil {
+		return fmt.Errorf("getOptOrEnvOrDefault: %w", err)
+	}
+	debug, _ := strconv.ParseBool(debugString)
+
 	client, err := bigquery.NewClient(ctx, project)
 	if err != nil {
 		return fmt.Errorf("bigquery.NewClient: %w", err)
@@ -85,7 +96,7 @@ func Run(ctx context.Context) (err error) {
 		}
 	}()
 
-	generatedCode, err := Generate(ctx, client, dataset)
+	generatedCode, err := Generate(ctx, client, dataset, debug)
 	if err != nil {
 		return fmt.Errorf("Generate: %w", err)
 	}
@@ -98,7 +109,7 @@ func Run(ctx context.Context) (err error) {
 	return nil
 }
 
-func Generate(ctx context.Context, client *bigquery.Client, dataset string) (generatedCode []byte, err error) {
+func Generate(ctx context.Context, client *bigquery.Client, dataset string, debug bool) (generatedCode []byte, err error) {
 
 	const head = `// Code generated by go run github.com/ginokent/bqschema-gen-go; DO NOT EDIT.
 
@@ -135,13 +146,25 @@ package bqschema
 	// NOTE(ginokent): combine
 	code := head + importCode + tail
 
+	if debug {
+		fmt.Println(">>>> DEBUG >>>>>>>>>>>>>>>>")
+		fmt.Println(code)
+		fmt.Println("<<<< DEBUG <<<<<<<<<<<<<<<<")
+	}
+
 	gen := []byte(code)
 
 	genFmt, err := format.Source(gen)
 	if err != nil {
 		return nil, fmt.Errorf("format.Source: %w", err)
 	}
 
+	if debug {
+		fmt.Println(">>>> DEBUG >>>>>>>>>>>>>>>>")
+		fmt.Println(string(genFmt))
+		fmt.Println("<<<< DEBUG <<<<<<<<<<<<<<<<")
+	}
+
 	genImports, err := imports.Process("", genFmt, nil)
 	if err != nil {
 		return nil, fmt.Errorf("imports.Process: %w", err)