AutoStruct/autostruct.go

package autostruct

import (
	"encoding/json"
	"fmt"
	"log"
	"os"
	"reflect"
	"strings"
)

// Generates structures given json
//
// Can also be used to generate structures via go code
type AutoStruct struct {
	StructName  string   // Name to prefix to all structures generated
	PackageName string   // Package to assign the new go file
	FileName    string   // The name to assign the new go file
	File        *os.File // Access to the new go file (writer)
}

// Sets up the AutoStruct to build a go file containing structures
//
// Structname is a prefix to add to all structures, if no prefix desired leave an empty string in place
func (a *AutoStruct) Init(fname, packname, structname string) error {
	a.StructName = structname
	a.FileName = fname
	a.PackageName = packname
	var err error
	if FileExists(a.FileName + ".go") {
		log.Printf("AutoStruct.Init('%s', '%s', '%s') => Warning, file exists, this is an experimental feature.", fname, packname, structname)
	}
	a.File, err = os.OpenFile(a.FileName+".go", os.O_CREATE|os.O_RDWR, 0666)
	if err != nil {
		return err
	}
	return nil
}

// Places the package name defined in the init
func (a *AutoStruct) PlacePackageName() {
	a.File.Write([]byte("package " + a.PackageName + "\n"))
}

// In cases where you use a specific type from another module
//
// Don't forget to call EndImports() to close this, go will be cranky
func (a *AutoStruct) StartImports() {
	a.File.Write([]byte("import (\n"))
}

// Adds a unambiguous import
//
// Use AddAliasImport() for 'alias "import"'
func (a *AutoStruct) AddImport(importname string) {
	a.File.Write([]byte("\t\"" + importname + "\"\n"))
}

// Adds an aliased import
//
// Ex  door "red-gree.com/door"
//
// Use AddImport() for a unambiguous import
func (a *AutoStruct) AddAliasImport(importalias, importname string) {
	a.File.Write([]byte("\t" + importalias + " \"" + importname + "\"\n"))
}

// Closes the import statement
func (a *AutoStruct) EndImports() {
	a.File.Write([]byte(")\n"))
}

// Begins a structure
func (a *AutoStruct) StartStruct(structname string) {
	a.File.Write([]byte("type " + a.StructName + structname + " struct {\n"))
}

// Adds a field to the structure
//
// Ex   Name string
//
// Use AddCommentField() to add a comment with the field
//
// Use AddJsonField() to add a json tag with the field
//
// Use AddJsonCommentField() to add a json tag and a comment
func (a *AutoStruct) AddField(fieldname, fieldtype string) {
	a.File.Write([]byte("\t" + fieldname + " " + fieldtype + "\n"))
}

// Adds a field to the structure (includes a comment about the field)
//
// Ex    Name string // The BBS user name
//
// Use AddField() to add a field without a comment or json tag
//
// Use AddJsonCommentField() to add a field with a comment and a json tag
//
// Use AddJsonField() to add a field with a json tag but no comment
func (a *AutoStruct) AddCommentField(fieldname, fieldtype, comment string) {
	a.File.Write([]byte("\t" + fieldname + " " + fieldtype + " // " + comment + "\n"))
}

// Adds a field to the structure (includes a json tag)
//
// Ex     Name string `json:"name"`
//
// Use json tag "-" to mark fields to not be in json's marshal or unmarshal process
//
// Use AddField() to add a field without a comment or json tag
//
// Use AddCommentField() to add a field without a json tag but with a comment
//
// Use AddJsonCommentField() to add a field with a json tag and a comment
func (a *AutoStruct) AddJsonField(fieldname, fieldtype, jsonname string) {
	a.File.Write([]byte("\t" + fieldname + " " + fieldtype + " `json:\"" + jsonname + "\"`\n"))
}

// Adds a field to the structure (includes both a json tag and a comment)
//
// Ex     Name string `json:"name"` // The BBS user name
//
// Use json tag "-" to mark fields to not be in json's marshal or unmarshal process
//
// Use AddJsonField() to add a field with a json tag but no comment
//
// Use AddField() to add a field without a comment or json tag
//
// Use AddCommentField() to add a field with a comment but no json tag
func (a *AutoStruct) AddJsonCommentField(fieldname, fieldtype, jsonname, comment string) {
	a.File.Write([]byte("\t" + fieldname + " " + fieldtype + " `json:\"" + jsonname + "\"` // " + comment + "\n"))
}

// Ends/Closes the structure
func (a *AutoStruct) EndStruct() {
	a.File.Write([]byte("}\n"))
}

// Adds some space between things
func (a *AutoStruct) Newline() {
	a.File.Write([]byte("\n"))
}

// Adds a single line comment
func (a *AutoStruct) Comment(comment string) {
	a.File.Write([]byte("// " + comment + "\n"))
}

// Closes the newly formed go file
func (a *AutoStruct) Close() {
	a.File.Close()
}

// Forms needed structures and a master structure
//
// TODO: Change it so it actually forms a map[string]string key=fieldname value=fieldtype
//       This will allow us to then form other structures we need as we iterate the data
func (a *AutoStruct) LoadJson(filename, structname string) (int, error) {
	var structsMade int
	var err error
	var file []byte
	file, err = os.ReadFile(filename + ".json")
	if err != nil {
		return structsMade, err
	}
	var data map[string]interface{}
	err = json.Unmarshal(file, &data)
	if err != nil {
		return structsMade, err
	}
	fmt.Printf("%#v\n", data)
	// Wrong, we actually want to store this then make any substructures then make the base struct
	a.StartStruct(structname)
	for k, v := range data {
		k = strings.ReplaceAll(k, "-", "_") // Replace '-' with '_'
		k = strings.ReplaceAll(k, " ", "")  // Remove ' '
		switch reflect.TypeOf(v).Kind() {
		case reflect.Array, reflect.Slice:
			// Array or slice []
			// Check all types are the same (else need new struct)
			// Iterate over nested array/slice and maps

			// Assuming all types are same
			var array []interface{} = v.([]interface{})
			a.AddField(k, "[]"+reflect.TypeOf(array[0]).String())
		case reflect.Map:
			// Map key, val
			// Check all types are the same (else need new struct)
			// Iterate over nested array/slice and maps

			// Assuming all types are same
			var mp map[string]interface{} = v.(map[string]interface{})
			var keys []string = make([]string, 0, len(mp))
			for k2 := range mp {
				keys = append(keys, k2)
			}
			a.AddField(k, "map[string]"+reflect.TypeOf(mp[keys[0]]).String())
		default:
			// Fallback
			a.AddField(k, reflect.TypeOf(v).String())
		}
	}
	structsMade += 1
	a.EndStruct()
	return structsMade, nil
}