// Copyright 2017-2025 WIT.COM Inc. All rights reserved.
// Use of this source code is governed by the GPL 3.0

package main

import (
	"bytes"
	"fmt"
	"io"
	"log"
	"reflect"
	"unicode/utf8"

	"go.wit.com/lib/protobuf/bugpb"
	"go.wit.com/lib/protobuf/forgepb"
	"golang.org/x/text/encoding/charmap"
	"google.golang.org/protobuf/proto"
)

func doDebug() {
	me.forge = forgepb.InitPB()
	me.forge.ScanGoSrc()
	if err := me.forge.ConfigSave(); err != nil {
		if err := me.forge.Repos.ConfigSave(); err != nil {
			err := ValidateProtoUTF8(me.forge.Repos)
			if err != nil {
				log.Printf("Protobuf UTF-8 validation failed: %v\n", err)
			}
			if err := bugpb.SanitizeProtoUTF8(me.forge.Repos); err != nil {
				log.Fatalf("Sanitization failed: %v", err)
			}
		}
		// badExit(err)
	}
	me.forge.SetConfigSave(true)
	me.forge.Exit()
	okExit("this never runs")
}

// ValidateProtoUTF8 checks all string fields in a proto.Message recursively.
func ValidateProtoUTF8(msg proto.Message) error {
	return validateValue(reflect.ValueOf(msg), "")
}

func validateValue(val reflect.Value, path string) error {
	if !val.IsValid() {
		return nil
	}

	if val.Kind() == reflect.Ptr {
		if val.IsNil() {
			return nil
		}
		return validateValue(val.Elem(), path)
	}

	switch val.Kind() {
	case reflect.Struct:
		for i := 0; i < val.NumField(); i++ {
			field := val.Field(i)
			fieldType := val.Type().Field(i)
			fieldPath := fmt.Sprintf("%s.%s", path, fieldType.Name)
			if err := validateValue(field, fieldPath); err != nil {
				return err
			}
		}

	case reflect.String:
		s := val.String()
		if !utf8.ValidString(s) {
			return fmt.Errorf("invalid UTF-8 string at %s: %q", path, s)
		}

	case reflect.Slice:
		if val.Type().Elem().Kind() == reflect.Uint8 {
			return nil // skip []byte
		}
		for i := 0; i < val.Len(); i++ {
			if err := validateValue(val.Index(i), fmt.Sprintf("%s[%d]", path, i)); err != nil {
				return err
			}
		}

	case reflect.Map:
		for _, key := range val.MapKeys() {
			valItem := val.MapIndex(key)
			if err := validateValue(valItem, fmt.Sprintf("%s[%v]", path, key)); err != nil {
				return err
			}
		}
	}

	return nil
}

// SanitizeProtoUTF8 fixes all invalid UTF-8 strings in a proto.Message recursively.
func SanitizeProtoUTF8(msg proto.Message) error {
	return sanitizeValue(reflect.ValueOf(msg), "")
}

func sanitizeValue(val reflect.Value, path string) error {
	if !val.IsValid() {
		return nil
	}

	if val.Kind() == reflect.Ptr {
		if val.IsNil() {
			return nil
		}
		return sanitizeValue(val.Elem(), path)
	}

	switch val.Kind() {
	case reflect.Struct:
		for i := 0; i < val.NumField(); i++ {
			field := val.Field(i)
			fieldType := val.Type().Field(i)
			if !field.CanSet() {
				continue
			}
			if err := sanitizeValue(field, fmt.Sprintf("%s.%s", path, fieldType.Name)); err != nil {
				return err
			}
		}

	case reflect.String:
		s := val.String()
		if !utf8.ValidString(s) {
			utf8Str, err := latin1ToUTF8(s)
			if err != nil {
				return fmt.Errorf("failed to convert %s to UTF-8: %v", path, err)
			}
			val.SetString(utf8Str)
		}

	case reflect.Slice:
		if val.Type().Elem().Kind() == reflect.Uint8 {
			return nil // skip []byte
		}
		for i := 0; i < val.Len(); i++ {
			if err := sanitizeValue(val.Index(i), fmt.Sprintf("%s[%d]", path, i)); err != nil {
				return err
			}
		}

	case reflect.Map:
		for _, key := range val.MapKeys() {
			valItem := val.MapIndex(key)
			newItem := reflect.New(valItem.Type()).Elem()
			newItem.Set(valItem)
			if err := sanitizeValue(newItem, fmt.Sprintf("%s[%v]", path, key)); err != nil {
				return err
			}
			val.SetMapIndex(key, newItem)
		}
	}

	return nil
}

func latin1ToUTF8(input string) (string, error) {
	reader := charmap.ISO8859_1.NewDecoder().Reader(bytes.NewReader([]byte(input)))
	result, err := io.ReadAll(reader)
	if err != nil {
		return "", err
	}
	return string(result), nil
}