import ctypes
import datetime
import os
import platform
import shutil
import sys
import traceback
import s3upload


def freespace(p):
     """
     FROM: http://atlee.ca/blog/2008/02/23/getting-free-diskspace-in-python/
           http://stackoverflow.com/questions/51658/cross-platform-space-remaining-on-volume-using-python
     Returns the number of free bytes on the drive that ``p`` is on
     """
     if platform.system() == 'Windows':
         free_bytes = ctypes.c_ulonglong(0)
         ctypes.windll.kernel32.GetDiskFreeSpaceExW(ctypes.c_wchar_p(p), None, None, ctypes.pointer(free_bytes))
         return free_bytes.value
     else:
         s = os.statvfs(p)
         return s.f_bsize * s.f_bavail

def directory_size(path):
    """
    FROM: http://stackoverflow.com/questions/1392413/calculating-a-directory-size-using-python
    """
    total_size = 0.0
    for dirpath, dirnames, filenames in os.walk(path):
        for f in filenames:
            fp = os.path.join(dirpath, f)
            total_size += os.path.getsize(fp)
    return total_size

def parse_date_dir(d, date_fmt):
    if not os.path.exists(d):
        raise ValueError('%s does not exist' % d)
    if not os.path.isdir(d):
        raise ValueError('%s is not a directory' % d)
    return datetime.datetime.strptime(os.path.basename(d), date_fmt)

def is_date_dir(d, date_fmt):
    try:
        parse_date_dir(d, date_fmt)
        return True
    except ValueError:
        return False

def get_directory_list(path, date_fmt='%Y%m%d'):
    parse_func = lambda d: parse_date_dir(d, date_fmt)
    subdirs = [os.path.join(path, child) for child in os.listdir(path)]
    datedirs = [d for d in subdirs if is_date_dir(d, date_fmt)]
    return sorted(datedirs, key=parse_func)
    

def upload_dirs_until_free(path, target_free_mbs, dryrun):
    starting_freespace = float(freespace(path))
    dirs_uploaded = 0
    files_uploaded = 0
    cur_freespace = starting_freespace
    reclaimed_space = 0.0
    error = False
    directory_list = get_directory_list(path)

    if not directory_list:
        print "Target directory %s has no subdirectories!" % path
        sys.exit(1)

    print "Target directory: %s" % path
    print "Starting freespace: %.02f MBs" % (starting_freespace / 1024 / 1024)
    print "Target freespace: %.02f MBs"  % target_free_mbs
    print "Image subdirectories: %s" % len(directory_list)

    if dryrun:
        print
        print '!!! Doing dryrun -- current free space will be estimated !!!'

    print
    try:
        for dir_to_upload in directory_list:
            if cur_freespace >= target_free_mbs * 1024 * 1024:
                break
        
            dir_size = directory_size(dir_to_upload)
            print 'Uploading %s (%.02f MBs)' % (dir_to_upload, dir_size / 1024 / 1024)

            res = s3upload.do_upload(dir_to_upload, verbose=False, dryrun=dryrun)
            files_uploaded += res['files_uploaded']
            print "%s files uploaded in %.02fs" % (res['files_uploaded'], res['sec_elapsed'])

            dirs_uploaded += 1
            reclaimed_space += dir_size

            if not dryrun:
                print "Deleting %s" % dir_to_upload
                shutil.rmtree(dir_to_upload)
                
            if dryrun:
                cur_freespace += dir_size 
            else:
                cur_freespace = float(freespace(path))
            print "%.02f MBs now free" % (cur_freespace / 1024 / 1024)
            print

    except Exception:
        print "An unexpected error occured!"
        error = True
        traceback.print_exc()

    print "---------------------------------------"
    if error:
        pass
    else:
        pass
    print "Finished successfully" if not error else "!!! Terminated abnormally !!!"
    print "Current free space: %.02f MBs" % (cur_freespace / 1024 / 1024)
    print "Reclaimed space: %.02f MBs" % (reclaimed_space / 1024 / 1024)
    print "Directories uploaded: %s" % dirs_uploaded
    print "Files uploaded: %s" % files_uploaded


if __name__ == '__main__':
    if not 4 <= len(sys.argv) <= 5:
        print "usage: dailyimgupload.py workingdir path megabytes [dryrun]"
        sys.exit(1)

    wd = sys.argv[1]
    if not os.path.isdir(wd):
        print "Invalid working directory: %s" % wd
        sys.exit(1)
    print "Switching working directory to %s" % wd
    os.chdir(wd)

    path = sys.argv[2]
    if not os.path.isdir(path):
        print "invalid image directory: %s" % path
        sys.exit(1)

    mbs = sys.argv[3]
    try:
        target_free_mbs = float(mbs)
    except ValueError:
        print "invalid number of megabytes: %s" % mbs
        sys.exit(1)

    if len(sys.argv) == 5:
        dryrun = sys.argv[4]
        if dryrun in ('true', 'false'):
            dryrun = dryrun == 'true'
        else:
            print "invalid dry run argument: %s (must be either 'true' or 'false')" % dryrun
            sys.exit(1)
    else:
        dryrun = True

    upload_dirs_until_free(path, target_free_mbs, dryrun)