package main

import (
	"bytes"
	"fmt"
	"text/template"

	"google.golang.org/protobuf/compiler/protogen"
)

const ModelTpl = `const TableName{{.ModelName}} = "{{.TableName}}"
func (t *{{.ModelName}}) TableName() string {
	return "{{.TableName}}"
}

{{range $structs := .DbFields}}
func (m *{{$.ModelName}}) Get{{$structs.FieldName}}Field() string {
	return "{{$structs.BsonField}}"
}
{{end}}
`

type DbField struct {
	FieldName string
	BsonField string
}

type model struct {
	ModelName   string
	TableName   string
	PackageName string
	DbFields    []*DbField
}

func GenerateModel(message *protogen.Message, packageName string) (string, error) {
	var name = message.GoIdent.GoName
	var entry = &model{
		ModelName:   name,
		TableName:   GetCommentTableName(message),
		PackageName: packageName,
	}

	for _, field := range message.Fields {
		var dbField = &DbField{
			FieldName: field.GoName,
			BsonField: GetCommentBsonName(field),
		}
		entry.DbFields = append(entry.DbFields, dbField)
	}

	tpl, err := template.New("model_tpl").Parse(ModelTpl)
	if err != nil {
		return "", fmt.Errorf("parse %s template failed: %v", name, err)
	}

	tpl.DefinedTemplates()
	var buf bytes.Buffer
	if err = tpl.Execute(&buf, entry); err != nil {
		return "", fmt.Errorf("execute %s template failed: %v", name, err)
	}

	return buf.String(), nil
}