from_swagger/main.go

package main

import (
	"encoding/json"
	"fmt"
	"os"
	"sort"
	"strings"
)

type config struct {
	Openapi string `json:"openapi"`
	Info    struct {
		Title       string `json:"title"`
		Description string `json:"description"`
		Version     string `json:"version"`
	} `json:"info"`
	Paths map[string]map[string]struct {
		Tags        []string `json:"tags"`
		Summary     string   `json:"summary"`
		OperationID string   `json:"operationId"`
		Parameters  []struct {
			Name   string   `json:"name"`
			In     string   `json:"in"`
			Schema property `json:"schema"`
		} `json:"parameters"`
		RequestBody *struct {
			Content struct {
				ApplicationJSON struct {
					Schema property `json:"schema"`
				} `json:"application/json"`
			} `json:"content"`
			Required bool `json:"required"`
		} `json:"requestBody"`
		Responses struct {
			Num200 struct {
				Description string `json:"description"`
				Content     struct {
					ApplicationJSON struct {
						Schema property `json:"schema"`
					} `json:"application/json"`
				} `json:"content"`
			} `json:"200"`
		} `json:"responses"`
	} `json:"paths"`
	Components struct {
		Models map[string]struct {
			Type       string              `json:"type"`
			Properties map[string]property `json:"properties"`
		} `json:"schemas"`
	} `json:"components"`
}

type property struct {
	Type     string `json:"type"`
	Format   string `json:"format"`
	Nullable bool   `json:"nullable"`
	Ref      string `json:"$ref"`
	AllOf    []struct {
		Ref string `json:"$ref"`
	} `json:"allOf"`
	Items struct {
		Ref string `json:"$ref"`
	} `json:"items"`
}

func (p *property) toKt() string {
	sb := strings.Builder{}
	if p.Type != "" {
		sb.WriteString(fmt.Sprintf("%s", toMicronautKotlinType(*p)))
	}
	if p.Ref != "" {
		sb.WriteString(fmt.Sprintf("%s", refToName(p.Ref)))
	}
	if len(p.AllOf) != 0 {
		sb.WriteString(fmt.Sprintf("%s", refToName(p.AllOf[0].Ref)))
	}
	if p.Nullable {
		sb.WriteString(fmt.Sprintf("?"))
	}
	return sb.String()
}

func main() {
	b, err := os.ReadFile("swaggers/example_1.json")
	if err != nil {
		panic(err)
	}
	config := &config{}
	if err := json.Unmarshal(b, config); err != nil {
		panic(err)
	}

	res := toMicronautKotlin(config)

	if err := os.WriteFile("res/models.kt", []byte(res["models"]), 0600); err != nil {
		panic(err)
	}

	if err := os.WriteFile("res/client.kt", []byte(res["client"]), 0600); err != nil {
		panic(err)
	}
}

func toMicronautKotlin(config *config) map[string]string {
	sbModels := strings.Builder{}
	sbModels.WriteString("package models\n\n")
	for modelName, model := range config.Components.Models {
		sbModels.WriteString(fmt.Sprintf("data class %s(\n", modelName))
		for name, value := range model.Properties {
			sbModels.WriteString(fmt.Sprintf("\tvar %s: ", name))
			sbModels.WriteString(value.toKt())
			sbModels.WriteString(",\n")
		}
		sbModels.WriteString(")\n\n")
	}

	sbClient := strings.Builder{}
	sbClient.WriteString("package client\n\n")
	sbClient.WriteString("import io.micronaut.http.HttpResponse\n")
	sbClient.WriteString("import io.micronaut.http.annotation.*\n")
	sbClient.WriteString("import io.micronaut.http.client.annotation.Client\n")
	sbClient.WriteString("\n")
	sbClient.WriteString("@Client(value = \"INPUT URL\")\n")
	sbClient.WriteString("interface GDSClient {\n\n")

	pathKeys := getSortKeys(config.Paths)
	for _, path := range pathKeys {
		methods := config.Paths[path]
		methodKeys := getSortKeys(methods)
		for _, method := range methodKeys {
			v := methods[method]

			if v.Summary != "" {
				sbClient.WriteString(fmt.Sprintf("\t// %s\n", v.Summary))
			}
			sbClient.WriteString(fmt.Sprintf("\t@%s(value = \"%s\")\n", toMicronautKotlinMethod(method), path))
			sbClient.WriteString(fmt.Sprintf("\tfun %s(", v.OperationID))

			if len(v.Parameters) != 0 || v.RequestBody != nil {
				sbClient.WriteString("\n")
			}
			for _, p := range v.Parameters {
				sbClient.WriteString("\t\t")
				switch p.In {
				case "header":
					sbClient.WriteString("@Header")
				case "path":
					sbClient.WriteString("@PathVariable")
				default:
					sbClient.WriteString(fmt.Sprintf("(type %s not support)", p.In))
				}
				sbClient.WriteString(fmt.Sprintf(" %s: %s,\n", p.Name, p.Schema.toKt()))
			}
			if v.RequestBody != nil {
				sbClient.WriteString(fmt.Sprintf("\t\t@Body %s: %s,\n", "body", v.RequestBody.Content.ApplicationJSON.Schema.toKt()))
			}
			if len(v.Parameters) != 0 || v.RequestBody != nil {
				sbClient.WriteString("\t")
			}

			sbClient.WriteString(")")

			resp := v.Responses.Num200.Content.ApplicationJSON.Schema.toKt()
			if resp != "" {
				sbClient.WriteString(fmt.Sprintf(": HttpResponse<%s>", resp))
			}
			sbClient.WriteString("\n\n")
		}
	}
	sbClient.WriteString("}\n\n")

	return map[string]string{
		"models": sbModels.String(),
		"client": sbClient.String(),
	}
}

func toMicronautKotlinType(prop property) string {
	switch prop.Type {
	case "string":
		return "String"
	case "integer":
		return "Int"
	case "boolean":
		return "Boolean"
	case "number":
		return "Double"
	case "array":
		return fmt.Sprintf("List<%s>", refToName(prop.Items.Ref))
	}
	return fmt.Sprintf("type %s not support", prop.Type)
}

func toMicronautKotlinMethod(method string) string {
	switch method {
	case "get":
		return "Get"
	case "post":
		return "Post"
	case "put":
		return "Put"
	case "delete":
		return "Delete"
	}
	return fmt.Sprintf("mmethod %s not support", method)
}

func refToName(ref string) string {
	arr := strings.Split(ref, "/")
	return arr[len(arr)-1]
}

func getSortKeys[T any](m map[string]T) []string {
	keys := make([]string, 0, len(m))
	for k := range m {
		keys = append(keys, k)
	}
	sort.Strings(keys)
	return keys
}