package config

import (
	"fmt"
	"os"
	"path/filepath"
	"strings"

	"google.golang.org/protobuf/encoding/protojson"
	"google.golang.org/protobuf/encoding/prototext"
	"google.golang.org/protobuf/proto"
)

var ErrProtoFilename error = fmt.Errorf("proto does not have Filename")

// writes the protobuf to disk
// uses the already configured Filename
func Save(pb proto.Message) error {
	fullname, err := GetFilename(pb)
	if err != nil {
		return err
	}
	return SaveToFilename(pb, fullname)
}

// special case. adds a header to the TEXT output
func SaveWithHeader(pb proto.Message, header string) error {
	err := saveTEXT(pb, header)
	return err
}

// writes the protobuf to disk (sets Filename if PB has 'Filename')
func SaveToFilename(pb proto.Message, fullname string) error {
	basedir, _ := filepath.Split(fullname)
	if err := os.MkdirAll(basedir, os.ModePerm); err != nil {
		return err
	}
	if strings.HasSuffix(fullname, ".pb") {
		return saveProto(pb, fullname)
	}
	if strings.HasSuffix(fullname, ".text") {
		return saveTEXT(pb, "")
	}
	if strings.HasSuffix(fullname, ".json") {
		return saveJSON(pb)
	}
	return fmt.Errorf("unknown filetype '%s'", fullname)
}

func saveProto(pb proto.Message, fullname string) error {
	if !strings.HasSuffix(fullname, ".pb") {
		// todo: append .text here?
		return fmt.Errorf("%s needs to end in '.pb'", fullname)
	}

	dir, name := filepath.Split(fullname)
	if name == "" {
		return fmt.Errorf("filename was blank")
	}
	if err := os.MkdirAll(dir, os.ModePerm); err != nil {
		return err
	}

	data, err := proto.Marshal(pb)
	if err != nil {
		return err
	}

	return configWrite(fullname, data)
}

func saveTEXT(pb proto.Message, header string) error {
	// get pb.Filename if it is there in the .proto file
	fullname, err := GetFilename(pb)
	if err != nil {
		return err
	}
	fullname = strings.TrimSpace(fullname)
	if fullname == "" {
		return fmt.Errorf("saveTEXT() pb.Filename was blank")
	}

	if !strings.HasSuffix(fullname, ".text") {
		// todo: append .text here?
		return fmt.Errorf("not .text file: %s", fullname)
	}

	dir, name := filepath.Split(fullname)
	if name == "" {
		return fmt.Errorf("filename was blank")
	}
	if err := os.MkdirAll(dir, os.ModePerm); err != nil {
		return err
	}

	data := prototext.Format(pb)

	err = configWrite(fullname, []byte(data))
	if err != nil {
		return err
	}
	return nil
}

func saveJSON(pb proto.Message) error {
	// get pb.Filename if it is there in the .proto file
	fullname, err := GetFilename(pb)
	if err != nil {
		return err
	}
	if !strings.HasSuffix(fullname, ".text") {
		// todo: append .text here?
		return fmt.Errorf("not .text file: %s", fullname)
	}

	dir, name := filepath.Split(fullname)
	if name == "" {
		return fmt.Errorf("filename was blank")
	}
	if err := os.MkdirAll(dir, os.ModePerm); err != nil {
		return err
	}

	data := protojson.Format(pb)

	fullname += ".json"

	err = configWrite(fullname, []byte(data))
	if err != nil {
		return err
	}
	return nil
}

func configWrite(fullname string, data []byte) error {
	cfgfile, err := os.OpenFile(fullname, os.O_RDWR|os.O_CREATE|os.O_TRUNC, 0644)
	defer cfgfile.Close()
	if err != nil {
		return err
	}
	_, err = cfgfile.Write(data)
	return err
}