# coding: utf-8
# Olaf, Dec 2015, Pythonista 1.6 beta

'''Appex GetFromURL
Pythonista app extension for use on share sheet of other apps to import file from URL into Pythonista
The file is saved at HOME/DESTINATION without user interaction (no 'save as' dialog) unless duplicate'''

from __future__ import print_function
try:
    import appex, console, contextlib, itertools, os, os.path, sys, time, urllib, urlparse
except ImportError:
    assert False, 'This script needs the appex module in Pythonista version > 1.5'

HOME, DESTINATION = 'Documents', 'FromURL' # you can change DESTINATION to any name of your liking

@contextlib.contextmanager
def callfunctionafterwardswithsec(function):
    '''Context-manager that calls function with duration of with block (sec) after termination

    >>> def pr_sec(sec): print('Duration {:3.2} sec'.format(sec))
    >>> with callfunctionafterwardswithsec(pr_sec): pass
    Duration 0.0 sec'''

    start = time.clock()
    yield
    end = time.clock()
    function(end - start)

def left_subpath_upto(path, sentinel):
    '''Left part (subpath) of path upto and including sentinel

    >>> print(left_subpath_upto('a/b/c', 'b'))
    a/b'''

    while path:
        head, tail = os.path.split(path)
        if tail == sentinel:
            break
        path = head
    return path

def iter_pad(length, arg0, *args):
    '''Iterator to pad arguments (at least 1) to specified length by repetition of final argument

    >>> print(''.join(iter_pad(3, 'a', 'b')))
    abb'''

    args = (arg0,) + args
    return itertools.islice(itertools.chain(args, itertools.repeat(args[-1])), length)

def parse_into_paths(input_url, HOME=HOME, DESTINATION=DESTINATION):
    '''Parse input URL into paths tuple for further processing

    >>> parse_into_paths('http://test.org/x.py', DESTINATION='TEST') # doctest: +ELLIPSIS
    ('x.py', 'http://test.org', 'Documents/TEST', '/private/var/.../TEST', '/priv.../TEST/x.py', True)'''

    url_tuple = urlparse.urlparse(input_url)
    scheme, netloc, basename = url_tuple.scheme, url_tuple.netloc, os.path.basename(url_tuple.path)
    input_short = urlparse.urlunparse(iter_pad(len(url_tuple), scheme, netloc, ''))
    output_short = os.path.join(HOME, DESTINATION)
    output_dir = os.path.join(left_subpath_upto(sys.argv[0], HOME), DESTINATION)
    output_path = os.path.join(output_dir, basename)
    is_Python = os.path.splitext(basename)[1].lower() == '.py'
    return basename, input_short, output_short, output_dir, output_path, is_Python

def copy_url(input_url):
    '''Write a copy of the file at input_url to HOME/DESTINATION
    if the destination directory doesn't exist, it is created
    if the destination file already exists, the user can cancel or overwrite
    if it is a Python file, a comment line is added to log the origin'''

    basename, input_short, output_short, output_dir, output_path, is_Python = parse_into_paths(input_url)

    if not os.path.exists(output_dir):
        os.mkdir(output_dir)
        console.hud_alert('Created destination directory {}'.format(output_short))
    if os.path.exists(output_path):
        try:
            console.alert('Duplicate file',
                          '{} already exists in {}'.format(basename, output_short),
                          'Overwrite') # or Cancel
        except KeyboardInterrupt:
            return

    with contextlib.closing(urllib.urlopen(input_url)) as input:
        data = input.read()
        console.hud_alert('Got {} ({} chars) from {}'.format(basename, len(data), input_short))
    with open(output_path, 'wb') as output:
        if is_Python:
            datetime = time.strftime('%a %d-%b-%Y %H:%M:%S', time.gmtime())
            output.write('# Retrieved from {} on {}\n\n'.format(input_url, datetime))
        output.write(data)
        console.hud_alert('Wrote {} to {}'.format(basename, output_short))

def main():
    '''App extension logic, with unit tests if run within Pythonista'''

    if appex.is_running_extension():
        if appex.get_url():
            copy_url(appex.get_url())
            appex.finish()
        else:
            console.hud_alert('No input URL found', 'error')
    else:
        console.hud_alert('This script must be run from the sharing extension', 'error')
        import doctest
        doctest.testmod()

if __name__ == '__main__':
    main()