#!/usr/bin/python3
"""
Script for periodical cleaning of log or backup folders.
This script will check for disk space in folderToObserve
and make sure that there's at least minDiskSpaceGB free space
oldest files will be removed first regardless of their folder

empty folders are removed, links are not followed

the params can be provided in command line like:
diskFreeKeep.py 10 /myFolder1 /otherFolder /asManyULike

more folders can be provided, but they must be from same filesystem
"""
import os, sys, datetime

foldersToObserve = ['/tmp']
minDiskSpaceGB = 1  # gigabytes
minDiskSpace = 1024 * 1024 * 1024;
# if true we print initial content of folder to observe
printContent = True


def files_to_delete(folders):
    files = []
    for rootfolder in folders:
        files.extend(
            os.path.join(dirname, filename)
            for dirname, dirnames, filenames in os.walk(rootfolder)
            for filename in filenames
        )
    files.sort(key=getFileTime, reverse=True)
    return files


def getFileTime(file):
    return os.lstat(file).st_mtime


def free_space_up_to(free_bytes_required, rootfolder):
    file_list = files_to_delete(rootfolder)
    if printContent:
        print("files in folder", len(file_list))
        print("\n==============");
        for file in file_list:
            print(datetime.datetime.fromtimestamp(os.lstat(file).st_mtime).isoformat(),
                  '{:10.3f}'.format(round(os.lstat(file).st_size / 1024 / 1024, 3)),
                  "MB",
                  file)
        print("==============\n");
    rf = os.open(rootfolder[0], os.O_RDONLY)
    for fileToRemove in file_list:
        try:
            statv = os.fstatvfs(rf)
            if statv.f_bfree * statv.f_bsize >= free_bytes_required:
                print("free space now:", '{:10.3f}'.format(round(statv.f_bfree * statv.f_bsize / 1024 / 1024, 3)), "MB")
                print("We have enough space now")
                break
            print("free space now:", '{:10.3f}'.format(round(statv.f_bfree * statv.f_bsize / 1024 / 1024, 3)), "MB", "removing file", fileToRemove)
            os.remove(fileToRemove)
        except:
            print("Oops!", sys.exc_info()[0], "occured.")


def setParams(cliParams):
    global minDiskSpace, minDiskSpaceGB, foldersToObserve, printContent

    if len(cliParams) > 1:
        if cliParams[1]:
            minDiskSpaceGB = float(cliParams[1])

    if len(cliParams) > 2:
        foldersToObserve = cliParams[2:]

    minDiskSpace = float(minDiskSpaceGB) * 1024 * 1024 * 1024
    print("Will free up folder", foldersToObserve, "until there's free", minDiskSpaceGB, "GB")


def deleteEmptyFolders(folderToDelete, removeRoot=False):
    if not removeRoot:
        print ("will try to delete empty folders from", folderToDelete)
    try:
        files = os.listdir(folderToDelete)
        if len(files):
            for f in files:
                fullpath = os.path.join(folderToDelete, f)
                if os.path.isdir(fullpath):
                    deleteEmptyFolders(fullpath, True)
        # if folder empty, delete it
        files = os.listdir(folderToDelete)
        if len(files) == 0 and removeRoot:
            print("Removing empty folder:", folderToDelete)
            os.rmdir(folderToDelete)
    except:
        print("error while deleting empty folders", sys.exc_info())


if __name__ == "__main__":
    setParams(sys.argv)
    free_space_up_to(minDiskSpace, foldersToObserve)
    for folderToDelete in foldersToObserve:
        deleteEmptyFolders(folderToDelete)