package config

// loads from the users .cache/ dir
//
// GOAL: always work. When in doubt, delete things in ~/.cache/
// RULE: always use raw .pb files, never human readable .text or .json files
//
// deletes files when versions don't match
// deletes files when filenames can't be set
// deletes anything that doesn't work
//
// This is important to avoid unmarshalling garbage protobuf data

import (
	"errors"
	"fmt"
	"os"

	"go.wit.com/lib/env"
	"google.golang.org/protobuf/proto"
)

// loads foo.proto from ~/.cache/<appname>/foo.pb
func LoadCacheDir(pb proto.Message) error {
	appname, err := env.GetAppname() // already configured by your application
	if err != nil {
		return err
	}

	err = LoadCacheDirByAppname(pb, appname)
	return err
}

// loads foo.proto from ~/.cache/<appname>/foo.pb
func LoadCacheDirByAppname(pb proto.Message, appname string) error {
	protoname, err := GetProtobufName(pb) // defined in the foo.proto file
	if err != nil {
		return err
	}

	err = CreateCacheDirPB(pb, appname, protoname)
	return err
}

// checks the UUID and Version of the .pb file
func CreateCacheDirPB(pb proto.Message, dirname string, filename string) error {
	// Get ~/.cache/dirname/filename.text
	fullname := MakeCacheFilename(dirname, filename)

	_, err := SetFilename(pb, fullname)
	if err != nil {
		fmt.Println("lib/config PB file does not support Filename")
	}
	newver, curver, err := VersionCheckFile(pb, fullname)
	_, _ = newver, curver
	if err == nil {
		// everything is fine. Versions match. load file
		err = LoadFromFilename(pb, fullname)
		return err
	}
	if errors.Is(err, os.ErrNotExist) {
		// file is new, create the file
		err = SaveToFilename(pb, fullname)
		return err
	}
	// some other bad error
	return err
}

// checks the UUID and Version of the .pb file
func ForceCreateCacheDirPB(pb proto.Message, dirname string, filename string) error {
	// Get ~/.cache/dirname/filename.text
	fullname := MakeCacheFilename(dirname, filename)

	_, err := SetFilename(pb, fullname)
	if err != nil {
		fmt.Println("lib/config PB file does not support Filename")
	}
	newver, curver, err := VersionCheckFile(pb, fullname)
	_, _ = newver, curver
	if err == nil {
		// everything is fine. Versions match. load file
		err = LoadFromFilename(pb, fullname)
		if err == nil {
			return nil
		}
		fmt.Printf("lib/config Load() %s failed. Removing file. (%v)\n", fullname, err)
	}
	// Version Check failed.
	err = os.Remove(fullname)
	if err != nil {
		fmt.Printf("lib/config os.Remove() %s failed (%v)\n", fullname, err)
		return err
	}
	// if there is any err, recreate the file
	err = SaveToFilename(pb, fullname)
	return err
}