package config

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

	"go.wit.com/lib/ENV"
	"go.wit.com/log"
	"google.golang.org/protobuf/encoding/protojson"
	"google.golang.org/protobuf/encoding/prototext"
	"google.golang.org/protobuf/proto"
)

// loads foo.proto from ~/.cache/<appname>/foo.text
func CacheLoad(pb proto.Message) error {
	appname, err := ENV.GetAppname() // already configured by your application
	if err != nil {
		return err
	}
	protoname, err := GetProtobufName(pb) // defined in the foo.proto file
	if err != nil {
		return err
	}

	// Get ~/.cache/appname/protoname.text
	fullname := makeCacheFilename(appname, protoname)

	// get the current filename in the protobuf file
	curfilename, err := GetFilename(pb)
	if err != nil {
		return err
	}
	if curfilename == "" {
		// log.Printf("ConfigLoad() read in %s\n", fullname)
	}

	err = loadPB(pb, fullname)
	if err != nil {
		return ErrMarshal
	}

	// If the cache file is new or has moved, this updates it to correct filename
	// (the filename is what is used by pb.Save()
	if curfilename != fullname {
		_, err := SetFilename(pb, fullname)
		if err != nil {
			log.Info("FILENAME COULD NOT BE SET old=", curfilename)
			log.Info("FILENAME COULD NOT BE SET new=", fullname)
			return errors.Join(err, errors.New("something is wrong in lib/config"))
		}
	}
	return nil
}

// loads from the users .cache dir
// if the .proto file version changes, automatically delete the .pb
// file. This is important to avoid marshalling garbage data
// .cache files are treated as such, a "cache" file. don't keep important
// things in here. argv stores the information here for autodelete
func LoadCache(pb proto.Message, appname string, protoname string) error {
	cacheDir, _ := os.UserCacheDir()
	fullpath := filepath.Join(cacheDir, appname)
	os.MkdirAll(fullpath, os.ModePerm)
	fullname := filepath.Join(fullpath, protoname+".pb")
	_, err := SetFilename(pb, fullname)
	if err != nil {
		pb = nil
		os.Remove(fullname)
		return err
	}
	newver, curver, err := LoadVersionCheckPB(pb)
	if err != nil {
		pb = nil
		os.Remove(fullname)
		return err
	}
	_, _ = newver, curver
	return nil
}

func LoadVersionCheckPB(pb proto.Message) (string, string, error) {
	var newver string
	var pbver string
	var err error

	fullname, err := GetFilename(pb)
	if err != nil {
		return newver, pbver, err
	}
	// text is supposed to be "easy". Don't verify 'version'
	if strings.HasSuffix(fullname, ".text") {
		err = loadTEXT(pb, fullname)
		return newver, pbver, err
	}

	// verify 'version' for .pb files
	// application should die if they don't match
	var worked bool
	newver, err = GetString(pb, "version")
	if err != nil {
		return newver, pbver, err
	}
	// maybe don't really verify .json files (?)
	// doing it for now anyway. maybe just return an error
	if strings.HasSuffix(fullname, ".json") {
		if err = loadJSON(pb, fullname); err != nil {
			return newver, pbver, err
		}
		worked = true
	}
	if strings.HasSuffix(fullname, ".pb") {
		if err = loadPB(pb, fullname); err != nil {
			return newver, pbver, err
		}
		_, err = SetFilename(pb, fullname)
		if err != nil {
			return newver, pbver, err
		}
		worked = true
	}
	if !worked {
		return newver, pbver, fmt.Errorf("unknown filetype '%s'", fullname)
	}
	// get the version from the current PB saved on disk
	pbver, _ = GetString(pb, "version")
	if newver != pbver {
		return newver, pbver, VersionMismatch
	}
	return newver, pbver, nil
}

// uses the version to die. This is needed because loading binary
// protobuf files with rearranged messages is indeterminate
func LoadPB(pb proto.Message) error {
	fullname, err := GetFilename(pb)
	if fullname == "" {
		panic("config.LoadPB() got blank filename = ''")
	}
	if err != nil {
		return err
	}
	// this code needs work
	newver, pbver, err := LoadVersionCheckPB(pb)
	if errors.Is(err, os.ErrNotExist) {
		return err
	}
	if errors.Is(err, VersionMismatch) || (newver != pbver) {
		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)
	}
	if err != nil {
		// return to let the application figure this out
		return err
	}
	return nil
}

func LoadFromFilename(pb proto.Message, fullname string) error {
	return LoadFile(pb, fullname)
}

func LoadFile(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 LoadConfigPB(pb proto.Message, appname string, protoname string) (string, error) {
	var fullname string
	if strings.HasPrefix(appname, "/") {
		fullname = filepath.Join(appname, protoname+".pb")
	} else {
		configDir, err := os.UserConfigDir()
		if err != nil {
			return "", err
		}

		fullname = filepath.Join(configDir, appname, protoname+".pb")
	}

	data, err := loadFile(fullname)
	if err != nil {
		return fullname, err
	}

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

	return fullname, 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
}

/* 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
}
*/

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
}