feat: add markdown generation to config generator (#652)

gen/gen_md.go

@@ -0,0 +1,127 @@
+package main
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io/fs"
+	"log/slog"
+	"os"
+	"reflect"
+	"strings"
+
+	"github.com/steveiliop56/tinyauth/internal/config"
+)
+
+type MarkdownEntry struct {
+	Env         string
+	Flag        string
+	Description string
+	Default     any
+}
+
+func generateMarkdown() {
+	cfg := config.NewDefaultConfiguration()
+	entries := make([]MarkdownEntry, 0)
+
+	root := reflect.TypeOf(cfg).Elem()
+	rootValue := reflect.ValueOf(cfg).Elem()
+	rootPath := "tinyauth."
+
+	walkAndBuild(root, rootValue, rootPath, &entries, buildMdEntry, buildMdMapEntry, buildMdChildPath)
+	compiled := compileMd(entries)
+
+	err := os.Remove("config.gen.md")
+	if err != nil && !errors.Is(err, fs.ErrNotExist) {
+		slog.Error("failed to remove example env file", "error", err)
+		os.Exit(1)
+	}
+
+	err = os.WriteFile("config.gen.md", compiled, 0644)
+	if err != nil {
+		slog.Error("failed to write example env file", "error", err)
+		os.Exit(1)
+	}
+}
+
+func buildMdEntry(child reflect.StructField, childValue reflect.Value, parentPath string, entries *[]MarkdownEntry) {
+	desc := child.Tag.Get("description")
+	tag := child.Tag.Get("yaml")
+
+	if tag == "-" {
+		return
+	}
+
+	value := childValue.Interface()
+
+	entry := MarkdownEntry{
+		Env:         strings.ToUpper(strings.ReplaceAll(parentPath, ".", "_")) + strings.ToUpper(child.Name),
+		Flag:        fmt.Sprintf("--%s%s", strings.TrimPrefix(parentPath, "tinyauth."), tag),
+		Description: desc,
+	}
+
+	switch childValue.Kind() {
+	case reflect.Slice:
+		sl, ok := value.([]string)
+		if !ok {
+			slog.Error("invalid default value", "value", value)
+			return
+		}
+		entry.Default = fmt.Sprintf("`%s`", strings.Join(sl, ","))
+	default:
+		entry.Default = fmt.Sprintf("`%v`", value)
+	}
+	*entries = append(*entries, entry)
+}
+
+func buildMdMapEntry(child reflect.StructField, parentPath string, entries *[]MarkdownEntry) {
+	fieldType := child.Type
+
+	if fieldType.Key().Kind() != reflect.String {
+		slog.Info("unsupported map key type", "type", fieldType.Key().Kind())
+		return
+	}
+
+	tag := child.Tag.Get("yaml")
+
+	if tag == "-" {
+		return
+	}
+
+	mapPath := parentPath + tag + ".[name]."
+	valueType := fieldType.Elem()
+
+	if valueType.Kind() == reflect.Struct {
+		zeroValue := reflect.New(valueType).Elem()
+		walkAndBuild(valueType, zeroValue, mapPath, entries, buildMdEntry, buildMdMapEntry, buildMdChildPath)
+	}
+}
+
+func buildMdChildPath(parent string, child string) string {
+	return parent + strings.ToLower(child) + "."
+}
+
+func compileMd(entries []MarkdownEntry) []byte {
+	buffer := bytes.Buffer{}
+
+	buffer.WriteString("# Tinyauth configuration reference\n\n")
+	buffer.WriteString("| Environment | Flag | Description | Default |\n")
+	buffer.WriteString("| - | - | - | - |\n")
+
+	previousSection := ""
+
+	for _, entry := range entries {
+		if strings.Count(entry.Env, "_") > 1 {
+			section := strings.Split(strings.TrimPrefix(entry.Env, "TINYAUTH_"), "_")[0]
+			if section != previousSection {
+				buffer.WriteString("\n## " + strings.ToLower(section) + "\n\n")
+				buffer.WriteString("| Environment | Flag | Description | Default |\n")
+				buffer.WriteString("| - | - | - | - |\n")
+				previousSection = section
+			}
+		}
+		fmt.Fprintf(&buffer, "| `%s` | `%s` | %s | %s |\n", entry.Env, entry.Flag, entry.Description, entry.Default)
+	}
+
+	return buffer.Bytes()
+}