package main

import (
	"log"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	"time"

	"github.com/djherbis/times"
)

var timeUnits = map[string]int64{
	"ms": 1,
	"s":  1000,
	"m":  1000 * 60,
	"h":  1000 * 60 * 60,
	"d":  1000 * 60 * 60 * 24,
	"M":  1000 * 60 * 60 * 24 * 30,
	"y":  1000 * 60 * 60 * 24 * 365,
}

var numFilesArchived = 0
var numFilesDeleted = 0

var valueRegex, _ = regexp.Compile(`\d+`)
var unitRegex, _ = regexp.Compile(`[a-zA-Z]+`)

func parseDuration(date string) int64 {
	var milliseconds int64 = 0

	date = strings.TrimSpace(date)
	var parts = strings.Split(date, "_")
	for _, part := range parts {
		part = strings.TrimSpace(part)
		log.Printf("Parsing date part: %s", part)
		var value = valueRegex.FindString(part)
		var unit = unitRegex.FindString(part)

		if value == "" || unit == "" {
			log.Println("Invalid date part: " + part)
			continue
		}

		if _, ok := timeUnits[unit]; !ok {
			log.Println("Invalid date unit: " + unit)
			continue
		}
		log.Printf("Part %s parsed as: Value: %s, Unit: %s", part, value, unit)

		var valueMs, _ = strconv.ParseInt(value, 10, 16)
		valueMs = valueMs * timeUnits[unit]
		milliseconds += valueMs
		log.Printf("Adding %dms to duration, now: %d", valueMs, milliseconds)
	}

	return milliseconds
}

func getEnv(key, def string) string {
	var value, exists = os.LookupEnv(key)
	if exists {
		return value
	}
	return def
}

func scanRoot() {
	log.Println("Scanning root directory...")
	filepath.Walk(constants.ROOT, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			log.Printf("Error scanning %s: %s", path, err)
			return nil
		}
		path = filepath.ToSlash(path)

		if path == constants.ROOT {
			log.Printf("Skipping root directory %s...", path)
			return nil
		}

		// I forgot why this code was here... It doesn't make sense to me now
		// if info.IsDir() {
		// 	log.Printf("Skipping directory %s...", path)
		// 	return filepath.SkipDir
		// }

		// We hope that IGNORED_DIRECTORIES is a small list, so we can afford to iterate over it
		// In fact iteration should be faster for small lists rather than hashing
		for _, ignoredDir := range constants.IGNORED_DIRECTORIES {
			log.Println(constants.IGNORED_DIRECTORIES, len(constants.IGNORED_DIRECTORIES))
			if strings.HasPrefix(path, ignoredDir) {
				log.Printf("Ignoring directory %s", path)
				return filepath.SkipDir
			}
		}

		processFile(path, info)
		return nil
	})
}

func scanArchive() {
	log.Println("Scanning archive...")
	filepath.Walk(constants.ROOT_ARCHIVE, func(path string, info os.FileInfo, err error) error {
		log.Printf("Scanning archive file %s...", path)
		if err != nil {
			log.Printf("Error scanning %s: %s", path, err)
			return nil
		}
		path = filepath.ToSlash(path)

		if path == constants.ROOT_ARCHIVE {
			log.Printf("Skipping root directory %s...", path)
			return nil
		}

		processArchiveFile(path, info)
		return nil
	})
}

func processFile(path string, info os.FileInfo) {
	now := time.Now().UnixMilli()
	log.Printf("Processing file %s...", path)

	timeType := "accessed"
	if constants.USE_MODTIME {
		timeType = "modified"
	}

	var fileTime int64
	if constants.USE_MODTIME {
		fileTime = times.Get(info).ModTime().UnixMilli()
	} else {
		fileTime = times.Get(info).AccessTime().UnixMilli()
	}

	timeDelta := now - fileTime
	log.Printf("File %s last %s at %d, %dms ago", path, timeType, fileTime, timeDelta)
	if timeDelta > constants.ARCHIVE_THRESHOLD {
		log.Printf("File %s was %s more than %dms ago, archiving...", path, timeType, constants.ARCHIVE_THRESHOLD)
		archiveFile(path)
	}
}

func processArchiveFile(path string, info os.FileInfo) {
	now := time.Now().UnixMilli()

	timeType := "accessed"
	if constants.USE_MODTIME {
		timeType = "modified"
	}

	var fileTime int64
	if constants.USE_MODTIME {
		fileTime = times.Get(info).ModTime().UnixMilli()
	} else {
		fileTime = times.Get(info).AccessTime().UnixMilli()
	}

	timeDelta := now - int64(fileTime)

	fileTimeFormatted := time.UnixMilli(fileTime).Format("15:04:05.000000")
	timeDeltaFormatted := time.Duration(timeDelta) * time.Millisecond
	log.Printf("File %s last %s at %s, %s ago", path, timeType, fileTimeFormatted, timeDeltaFormatted)

	if timeDelta > constants.DELETE_THRESHOLD {
		log.Printf("File %s was %s more than %dms ago, deleting...", path, timeType, constants.DELETE_THRESHOLD)
		deleteFile(path)
	}
}

func archiveFile(path string) {
	newPath := constants.ROOT_ARCHIVE + strings.Replace(path, constants.ROOT, "", 1)
	log.Printf("Archiving file %s to %s...", path, newPath)

	err := os.MkdirAll(filepath.Dir(newPath), os.ModePerm)
	if err != nil {
		log.Printf("Error creating directory %s: %s", filepath.Dir(newPath), err)
		return
	}
	// err := os.Rename(path, newPath)
	// if err != nil {
	// 	log.Printf("Error archiving file %s: %s", path, err)
	// 	return
	// }
	numFilesArchived++
}

func deleteFile(path string) {
	log.Printf("Deleting file %s...", path)
	// err := os.Remove(path)
	// if err != nil {
	// 	log.Printf("Error deleting file %s: %s", path, err)
	// 	return
	// }
	numFilesDeleted++
}

func cleanRoot() {
	files, err := os.ReadDir(constants.ROOT)
	if err != nil {
		log.Printf("Error reading root directory %s: %s", constants.ROOT, err)
		return
	}
	for _, file := range files {
		if !file.IsDir() {
			continue
		}
		empty, err := isDirEmpty(constants.ROOT + "/" + file.Name())
		if err != nil {
			log.Printf("Error checking if directory %s is empty: %s", file.Name(), err)
			continue
		}
		log.Printf("Directory %s isempty: %t", file.Name(), empty)
		if empty {
			log.Printf("Deleting empty directory %s", file.Name())
			err := os.RemoveAll(constants.ROOT + "/" + file.Name())
			if err != nil {
				log.Printf("Error deleting empty directory %s: %s", file.Name(), err)
			}
		}
	}
}
func isDirEmpty(dirPath string) (bool, error) {
	var empty = true
	var ferr error = nil

	filepath.Walk(dirPath, func(path string, info os.FileInfo, err error) error {
		if err != nil {
			log.Printf("Error scanning %s: %s", path, err)
			ferr = err
			return nil
		}
		if !info.IsDir() {
			empty = false
			log.Printf("Directory %s is not empty, found %s", dirPath, path)
			return filepath.SkipAll
		}
		return nil
	})
	return empty, ferr
}

type Constants struct {
	ROOT                string
	ROOT_ARCHIVE        string
	IGNORED_DIRECTORIES []string
	ARCHIVE_THRESHOLD   int64
	DELETE_THRESHOLD    int64
	SCAN_INTERVAL       time.Duration
	USE_MODTIME         bool
}

var constants = &Constants{}

func main() {
	log.SetFlags(log.Lmicroseconds)
	// Important: Access times don’t accumulate.
	// This implies that archiving the file won't alter its access time.
	// Therefore, assign X as the ARCHIVE_TIME and X + Y as the DELETE_TIME,
	// where X represents the duration it can exist in the folder,
	// and Y represents the duration it can exist in the archive.

	ROOT := filepath.ToSlash(strings.TrimSpace(getEnv("ROOT", "C:/tmp")))
	ROOT_ARCHIVE := filepath.ToSlash(strings.TrimSpace(getEnv("ROOT_ARCHIVE", ROOT+"/archive")))
	os.Mkdir(ROOT_ARCHIVE, os.ModePerm)
	IGNORED_DIRECTORIES := []string{}
	ignoredEnv := getEnv("IGNORED_DIRECTORIES", "")
	if ignoredEnv != "" {
		ignoredEnv = strings.TrimSpace(ignoredEnv)
		IGNORED_DIRECTORIES = append(IGNORED_DIRECTORIES, strings.Split(ignoredEnv, ",")...)
	}
	IGNORED_DIRECTORIES = append(IGNORED_DIRECTORIES, ROOT_ARCHIVE)
	for key, dir := range IGNORED_DIRECTORIES {
		IGNORED_DIRECTORIES[key] = filepath.ToSlash(strings.TrimSpace(dir))
	}
	ARCHIVE_THRESHOLD := parseDuration(getEnv("ARCHIVE_THRESHOLD", "1d"))
	DELETE_THRESHOLD := parseDuration(getEnv("DELETE_THRESHOLD", "12h"))
	SCAN_INTERVAL := time.Duration(parseDuration(getEnv("SCAN_INTERVAL", "1m"))) * time.Millisecond
	USE_MODTIME := strings.TrimSpace(getEnv("USE_MODTIME", "false")) == "true"

	constants.ROOT = ROOT
	constants.ROOT_ARCHIVE = ROOT_ARCHIVE
	constants.IGNORED_DIRECTORIES = IGNORED_DIRECTORIES
	constants.ARCHIVE_THRESHOLD = ARCHIVE_THRESHOLD
	constants.DELETE_THRESHOLD = DELETE_THRESHOLD
	constants.SCAN_INTERVAL = SCAN_INTERVAL
	constants.USE_MODTIME = USE_MODTIME

	log.Println("Input args parsed as:")
	log.Printf("ROOT: %s", ROOT)
	log.Printf("ROOT_ARCHIVE: %s", ROOT_ARCHIVE)
	log.Printf("IGNORED_DIRECTORIES: %s", IGNORED_DIRECTORIES)
	log.Printf("ARCHIVE_THRESHOLD: %s", time.Duration(ARCHIVE_THRESHOLD) * time.Millisecond)
	log.Printf("DELETE_THRESHOLD: %s", time.Duration(DELETE_THRESHOLD) * time.Millisecond)
	log.Printf("SCAN_INTERVAL: %s", SCAN_INTERVAL)
	log.Printf("USE_MODTIME: %s", strconv.FormatBool(USE_MODTIME))

	doRun()
	for {
		os.Exit(0)
		time.Sleep(SCAN_INTERVAL)
		doRun()
	}
}

func doRun() {
	log.Printf("Running at %s", time.Now().Format("15:04:05"))
	scanRoot()
	scanArchive()
	cleanRoot()
	log.Printf("Archived %d files, deleted %d files", numFilesArchived, numFilesDeleted)
	numFilesArchived = 0
	numFilesDeleted = 0
}