package main

import (
	"encoding/json"
	"log"
	"os"
	"path"
	"stream-poc2/model"
)

func pathForMedia(mediaID string) string {
	return path.Join("db", mediaID)
}

var metadataCache = make(map[string]model.MediaMetadata) // metadata is currently immutable, so we can make it simple here

func loadMediaMetadata(id string) (model.MediaMetadata, error) {
	var metadata model.MediaMetadata
	var ok bool

	metadata, ok = metadataCache[id]
	if ok {
		return metadata, nil
	}

	log.Printf("metadata for %s not found in cache... loading...", id)

	mediaPath := pathForMedia(id)
	if !isDir(mediaPath) {
		log.Println("media path dir does not exists", mediaPath)
		return model.MediaMetadata{}, os.ErrNotExist
	}

	f, err := os.OpenFile(path.Join(mediaPath, "meta.json"), os.O_RDONLY, 0)
	if err != nil {
		log.Println("Failed ot open file:", err)
		return model.MediaMetadata{}, err
	}
	defer func(f *os.File) {
		err := f.Close()
		if err != nil {
			log.Println("failed to close metadata file:", err)
		}
	}(f)

	err = json.NewDecoder(f).Decode(&metadata)
	if err != nil {
		log.Println("Failed to load metadata:", metadata)
		return model.MediaMetadata{}, err
	}

	metadataCache[id] = metadata

	return metadata, nil
}