Use generator to generate exceptions from yaml

Signed-off-by: Asai Neko <sugar@sne.moe>

cmd/gen_exception/exception.tmpl

@@ -0,0 +1,8 @@
+// Code generated by gen-exception; DO NOT EDIT.
+package exception
+
+const (
+{{- range .Items }}
+	{{ .Name }} = "{{ .Value }}"
+{{- end }}
+)

cmd/gen_exception/main.go

@@ -0,0 +1,97 @@
+//go:build ignore
+
+package main
+
+import (
+	"fmt"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+	"text/template"
+
+	"golang.org/x/text/cases"
+	"golang.org/x/text/language"
+	"gopkg.in/yaml.v3"
+)
+
+type ErrorItem struct {
+	Name  string
+	Value string
+}
+
+type TplData struct {
+	Items []ErrorItem
+}
+
+func toCamel(s string) string {
+	caser := cases.Title(language.English)
+	s = strings.ReplaceAll(s, "-", "_")
+	parts := strings.Split(s, "_")
+	for i := range parts {
+		parts[i] = caser.String(parts[i])
+	}
+	return strings.Join(parts, "")
+}
+
+func recursiveParse(prefix string, raw any, items *[]ErrorItem) {
+	switch v := raw.(type) {
+	case map[string]any:
+		for key, val := range v {
+			recursiveParse(prefix+toCamel(key), val, items)
+		}
+	case string:
+		*items = append(*items, ErrorItem{
+			Name:  prefix,
+			Value: v,
+		})
+	case int, int64:
+		*items = append(*items, ErrorItem{
+			Name:  prefix,
+			Value: fmt.Sprintf("%v", v),
+		})
+	}
+}
+
+func main() {
+	yamlDir := "internal/exception/definitions"
+	outputDir := "internal/exception"
+	tplPath := "cmd/gen_exception/exception.tmpl"
+
+	if _, err := os.Stat(tplPath); os.IsNotExist(err) {
+		log.Fatalf("Cannot found tmpl %s", tplPath)
+	}
+
+	funcMap := template.FuncMap{"ToCamel": toCamel}
+	tmpl := template.Must(template.New("exception.tmpl").Funcs(funcMap).ParseFiles(tplPath))
+
+	os.MkdirAll(outputDir, 0755)
+
+	files, _ := filepath.Glob(filepath.Join(yamlDir, "*.yaml"))
+	for _, yamlFile := range files {
+		content, err := os.ReadFile(yamlFile)
+		if err != nil {
+			log.Printf("Read file error: %v", err)
+			continue
+		}
+
+		var rawData any
+		if err := yaml.Unmarshal(content, &rawData); err != nil {
+			log.Printf("Unmarshal error in %s: %v", yamlFile, err)
+			continue
+		}
+
+		var items []ErrorItem
+		recursiveParse("", rawData, &items)
+
+		baseName := strings.TrimSuffix(filepath.Base(yamlFile), filepath.Ext(yamlFile))
+		outputFileName := baseName + "_gen.go"
+		outputPath := filepath.Join(outputDir, outputFileName)
+
+		f, _ := os.Create(outputPath)
+		tmpl.Execute(f, TplData{Items: items})
+		f.Close()
+
+		fmt.Printf("Generated: %s (%d constants)\n", outputPath, len(items))
+	}
+}