package config

import (
	"errors"
	"fmt"
	"os"
	"strings"

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

func LoadPB(pb proto.Message) error {
	return ReLoad(pb)
}

// uses the version to die. This is needed because loading binary
// protobuf files with rearranged messages is indeterminate
func ReLoad(pb proto.Message) error {
	fullname, err := GetFilename(pb)
	if (fullname == "") || (err != nil) {
		panic("config.LoadPB() got blank filename = ''")
	}
	// this code needs work
	newver, pbver, err := VersionCheckFile(pb, fullname)
	if errors.Is(err, os.ErrNotExist) {
		//
		err = SaveToFilename(pb, fullname)
		return err
	}
	if err != nil {
		fmt.Println("")
		fmt.Printf("VERSION new '%s' != cur PB '%s'\n", newver, pbver)
		fmt.Println("")
		fmt.Println("Your protobuf file is old and can not be loaded")
		fmt.Println("your application must decide how to handle this (delete or fix)")
		fmt.Println("always die here. application is broken")
		fmt.Println("You must delete or convert the file", fullname)
		fmt.Println("")
		// probably should ALWAYS PANIC HERE
		// upon further study, always die here is better than not
		s := fmt.Sprintf("protobuf version wrong. delete or fix %s", fullname)
		panic(s)
		// return to let the application figure this out
		// return err
	}
	err = LoadFromFilename(pb, fullname)
	return err
}

func LoadFromFilename(pb proto.Message, fullname string) error {
	if strings.HasSuffix(fullname, ".text") {
		return loadTEXT(pb, fullname)
	}
	if strings.HasSuffix(fullname, ".json") {
		return loadJSON(pb, fullname)
	}
	if strings.HasSuffix(fullname, ".pb") {
		return loadPB(pb, fullname)
	}

	return fmt.Errorf("unknown filetype '%s'", fullname)
}

func loadPB(pb proto.Message, fullname string) error {
	data, err := loadFile(fullname)
	if err != nil {
		// set pb.Filename that was attempted
		return err
	}

	if err = proto.Unmarshal(data, pb); err != nil {
		return err
	}

	return nil
}

func loadTEXT(pb proto.Message, fullname string) error {
	var data []byte
	var err error
	SetFilename(pb, fullname)
	if data, err = loadFile(fullname); err != nil {
		return err
	}

	// don't even bother with Marshal()
	if data == nil {
		return ErrEmpty // file is empty
	}

	// Unmarshal()
	if err = prototext.Unmarshal(data, pb); err != nil {
		return ErrMarshal
	}

	if fn, err := GetFilename(pb); err != nil {
		if fn != fullname {
			SetFilename(pb, fullname)
		}
	}
	return nil
}

// json files are backup Marshal() data in case .text Unmarshal() fails
// they always should have the ".text" filename in them
func loadJSON(pb proto.Message, fullname string) error {
	var data []byte
	var err error
	if data, err = loadFile(fullname); err != nil {
		return err
	}

	// don't even bother with Marshal()
	if data == nil {
		return ErrEmpty // file is empty
	}

	// Unmarshal()
	if err = protojson.Unmarshal(data, pb); err != nil {
		return ErrMarshal
	}

	if fn, err := GetFilename(pb); err != nil {
		if fn != fullname {
			SetFilename(pb, fullname)
		}
	}
	return nil
}

func loadFile(fullname string) ([]byte, error) {
	data, err := os.ReadFile(fullname)
	if errors.Is(err, os.ErrNotExist) {
		// if file does not exist, just return nil. this
		return nil, err
	}
	if err != nil {
		return nil, err
	}
	if len(data) == 0 {
		return data, ErrEmpty
	}
	return data, nil
}

/* left this here to remind myself just how dumb I can be

// dumb but simple to read logic
func missingConfig(fullname string) error {
	data1, err1 := os.ReadFile(fullname)
	if !errors.Is(err1, os.ErrNotExist) {
		return err1
	}

	data2, err2 := os.ReadFile(fullname + ".json")
	if !errors.Is(err2, os.ErrNotExist) {
		return err2
	}
	if errors.Is(err1, os.ErrNotExist) && errors.Is(err2, os.ErrNotExist) {
		return os.ErrNotExist
	}
	if (len(data1) == 0) && (len(data2) == 0) {
		return ErrEmpty
	}
	return nil
}
*/