package generator

import (
	"bytes"
	"embed"
	"html/template"
	"io"
	"io/fs"
	"os"
	"path"
	"time"

	"git.nobla.cn/golang/aeus/tools/gen/internal/types"
)

var (
	fileMap = map[string]string{
		"cmd/main.go":                   MainTemp,
		"internal/scope/scope.go":       ScopeTemp,
		"internal/service/service.go":   ServiceLoaderTemp,
		"api/v1/pb/greeter.proto":       GreeterTemp,
		"version/version.go":            VersionTemp,
		"Makefile":                      MakefileTemp,
		".gitignore":                    GitIgnoreTemp,
		"README.md":                     ReadmeTemp,
		"go.mod":                        GoModTemp,
		"webhook.yaml":                  WebhookTemp,
		"deploy/docker/deployment.yaml": DeploymentTemp,
	}
)

var (
	//go:embed third_party
	protoDir embed.FS
)

type (
	TemplateData struct {
		ShortName     string
		PackageName   string
		Datetime      string
		Version       string
		ImageRegistry string
	}
)

func writeFile(file string, buf []byte) (err error) {
	dirname := path.Dir(file)
	if _, err = os.Stat(dirname); err != nil {
		if err = os.MkdirAll(dirname, 0755); err != nil {
			return
		}
	}
	err = os.WriteFile(file, buf, 0644)
	return
}

func scanDir(s embed.FS, dirname string, callback func(file string) error) (err error) {
	var (
		entities []fs.DirEntry
	)
	if entities, err = s.ReadDir(dirname); err != nil {
		return nil
	}
	for _, entity := range entities {
		if entity.Name() == "." || entity.Name() == ".." {
			continue
		}
		name := path.Join(dirname, entity.Name())
		if entity.IsDir() {
			scanDir(s, name, callback)
		} else {
			if err = callback(name); err != nil {
				break
			}
		}
	}
	return
}

func Geerate(app *types.Applicetion) (err error) {
	shortName := app.ShortName()
	data := TemplateData{
		ShortName:     shortName,
		PackageName:   app.Package,
		Version:       app.Version,
		ImageRegistry: "{{IMAGE_REGISTRY_URL}}",
		Datetime:      time.Now().Format(time.DateTime),
	}
	if data.Version == "" {
		data.Version = "v0.0.1"
	}
	var t *template.Template
	writer := bytes.NewBuffer(nil)
	for name, tmpl := range fileMap {
		if t, err = template.New(name).Parse(tmpl); err != nil {
			return
		}
		if err = t.Execute(writer, data); err != nil {
			return
		}
		if err = writeFile(path.Join(shortName, name), writer.Bytes()); err != nil {
			return
		}
		writer.Reset()
	}
	if err = writeFile(shortName+".go", []byte("package "+shortName)); err != nil {
		return
	}
	err = scanDir(protoDir, "third_party", func(filename string) error {
		if fp, openerr := protoDir.Open(filename); openerr != nil {
			return openerr
		} else {
			if buf, readerr := io.ReadAll(fp); readerr == nil {
				writeFile(path.Join(shortName, filename), buf)
			}
			fp.Close()
		}
		return nil
	})
	return
}