// Copyright © 2023 Roberto Hidalgo <event-gateway@un.rob.mx>
// SPDX-License-Identifier: Apache-2.0
package config

import (
	"encoding/json"
	"fmt"
	"io/fs"
	"os"
	"os/signal"
	"syscall"

	"git.rob.mx/nidito/chinampa/pkg/logger"
)

var flog = logger.Sub("event-gateway.config.file")

var FS fs.FS

type fileSchema map[string]*Listener

type File struct {
	Path string
}

var _ Loader = &File{}

func (l *File) String() string {
	return fmt.Sprintf("FileLoader at %s", l.Path)
}

func (l *File) Load() (res []*Listener, err error) {
	var data []byte
	if FS != nil {
		data, err = fs.ReadFile(FS, l.Path)
	} else {
		data, err = os.ReadFile(l.Path)
	}
	if err != nil {
		return res, fmt.Errorf("could not read %s: %s", l.Path, err)
	}

	config := &fileSchema{}
	if err := json.Unmarshal(data, &config); err != nil {
		return res, fmt.Errorf("could not unserialize %s as json: %s", l.Path, err)
	}

	for name, listener := range *config {
		listener.ID = name
		res = append(res, listener)
	}
	return res, nil
}

func (l *File) Watch(reg chan []*Listener) {
	c := make(chan os.Signal, 1)
	signal.Notify(c, syscall.SIGHUP)
	go func() {
		for {
			<-c
			flog.Info("SIGHUP detected, reloading file configuration")
			res, err := l.Load()
			if err != nil {
				flog.Errorf("could not reload file configuration: %s", err)
			}
			flog.Info("Reloaded file configuration, updating listeners")
			reg <- res
		}
	}()
}