'''Python AppImage hooks
'''
import atexit
import os
import sys


_bin_at_start = os.listdir(sys.prefix + '/bin')
'''Initial content of the bin/ directory
'''


def patch_pip_install():
    '''Change absolute shebangs to relative ones following a `pip` install
    '''
    if not 'pip' in sys.modules:
        return

    appdir = os.getenv('APPDIR')
    python_x_y = 'python{:}.{:}'.format(*sys.version_info[:2])
    if sys.prefix != '{:}/opt/{:}'.format(appdir, python_x_y):
        return

    args = sys.argv[1:]
    if 'install' in args:
        for exe in os.listdir(sys.prefix + '/bin'):
            path = os.path.join(sys.prefix, 'bin', exe)

            if (not os.path.isfile(path)) or (not os.access(path, os.X_OK)) or \
               exe.startswith('python') or os.path.islink(path) or             \
               exe.endswith('.pyc') or exe.endswith('.pyo'):
                continue

            try:
                with open(path, 'r') as f:
                    header = f.read(2)
                    if header != '#!':
                        continue
                    content = f.read()
            except:
                continue

            shebang, body = content.split(os.linesep, 1)
            shebang = shebang.strip().split()
            executable = shebang.pop(0)
            if executable != sys.executable:
                head, altbody = body.split(os.linesep, 1)
                if head.startswith("'''exec' /"): # Patch for alt shebang
                    body = altbody.split(os.linesep, 1)[1]
                    executable = head.split()[1]
                    if executable != sys.executable:
                        continue
                else:
                    continue

            relpath = os.path.relpath(
                sys.prefix + '/../../usr/bin/' + python_x_y,
                sys.prefix + '/bin')
            shebang.append('"$@"')
            cmd = (
                '"exec"',
                '"$(dirname $(readlink -f ${0}))/' + relpath + '"',
                '"$0"',
                ' '.join(shebang)
            )

            try:
                with open(path, 'w') as f:
                    f.write('#! /bin/sh\n')
                    f.write(' '.join(cmd) + '\n')
                    f.write(body)
            except IOError:
                continue

            if exe in _bin_at_start:
                continue

            usr_dir = os.path.join(sys.prefix, '../../usr/bin')
            usr_exe = os.path.join(usr_dir, exe)
            if not os.path.exists(usr_exe):
                relpath = os.path.relpath(path, usr_dir)
                os.symlink(relpath, usr_exe)

    elif 'uninstall' in args:
        usr_dir = os.path.join(sys.prefix, '../../usr/bin')
        for exe in os.listdir(usr_dir):
            path = os.path.join(usr_dir, exe)
            if (not os.path.islink(path)) or                                   \
               os.path.exists(os.path.realpath(path)):
                continue
            os.remove(path)


if os.getenv('VIRTUAL_ENV') is None:
    atexit.register(patch_pip_install)
else:
    del _bin_at_start
    del patch_pip_install