package library

import (
	"errors"
	"io/fs"
	"path"
	"path/filepath"
	"strconv"
	"strings"
	"sync"
	"syscall"
	"time"
	"velvettear/badger/internal/config"
	"velvettear/badger/internal/database"
	"velvettear/badger/internal/log"
	"velvettear/badger/internal/tools"
)

func Import() {
	timestamp := tools.LogTimestamp()
	importDirectory := config.ImportDirectory()
	log.Info("import of directory '" + importDirectory + "' started...")
	// find files in import directory
	files := findFiles(importDirectory)
	if len(files) == 0 {
		log.InfoTimed("import of directory '"+importDirectory+"' finished, no files were detected", timestamp)
		return
	}
	// setup waitgroup and communication channels
	ipcMove := make(chan wrapper)
	ipcStore := make(chan wrapper)
	wait := new(sync.WaitGroup)
	wait.Add(3)
	// parse the files and store the generated metadata asynchronously
	go parseFiles(files, ipcMove, wait)
	go moveFiles(ipcMove, ipcStore, wait)
	go storeMetadata(ipcStore, wait)
	wait.Wait()
	close(ipcStore)
	// persist the in memory database to the filesystem
	database.Persist()
	// clean up empty directories
	deletionErrors := tools.DeleteEmpty(importDirectory)
	for _, error := range deletionErrors {
		dirNotEmptyError, ok := error.(*fs.PathError)
		if !ok || !errors.Is(dirNotEmptyError, syscall.ENOTEMPTY) {
			log.Error("encountered an error deleting directory", error.Error())
			continue
		}
		log.Warning("could not delete directy '" + dirNotEmptyError.Path + "' because it's not empty")
	}
	log.InfoTimed("import of directory '"+importDirectory+"' finished", timestamp)
}

func moveFiles(ipcInput chan wrapper, ipcOutput chan wrapper, wait *sync.WaitGroup) {
	timestamp := tools.LogTimestamp()
	log.Debug("starting loop to move files according to their metadata...")
	moved := 0
	for {
		wrapper := <-ipcInput
		target := path.Join(wrapper.metadata.GenerateTargetPath(), wrapper.metadata.GenerateFileName())
		if tools.Exists(target) {
			log.Warning("file '" + wrapper.metadata.Path + "' should be moved to already existing location '" + target + "', appending timestamp")
			extension := filepath.Ext("." + wrapper.metadata.Path)
			target = strings.Replace(target, extension, " [badger "+strconv.FormatInt(time.Now().UnixMilli(), 10)+"]"+extension, -1)
		}
		// if !wrapper.metadata.ShouldBeMoved(target) {
		// 	continue
		// }
		// TODO: uncomment for "real usage"
		error := tools.MoveFile(wrapper.metadata.Path, target)
		if error != nil {
			log.Error("encountered an error moving file '"+wrapper.metadata.Path+"' to '"+target+"'", error.Error())
			continue
		}
		moved++
		wrapper.metadata.Path = target
		ipcOutput <- wrapper
		if wrapper.last {
			break
		}
	}
	log.InfoTimed("successfully moved "+strconv.Itoa(moved)+" files according to their metadata", timestamp)
	wait.Done()
}