#!/usr/bin/env python3

__license__ = 'MIT'

import argparse
import json
import hashlib
import os
import subprocess
import tempfile
import urllib.request
import shlex
from collections import OrderedDict


parser = argparse.ArgumentParser()
parser.add_argument('packages', nargs='+')
parser.add_argument('--python2', action='store_true',
                    help='Look for a Python 2 package')
parser.add_argument('--cleanup', choices=['scripts', 'all'],
                    help='Select what to clean up after build')
parser.add_argument('--build-only', action='store_const',
                    dest='cleanup', const='all',
                    help='Clean up all files after build')
parser.add_argument('--output',
                    help='Specify output file name')
opts = parser.parse_args()

def get_pypi_url(name: str, filename: str) -> str:
    url = 'https://pypi.python.org/pypi/{}/json'.format(name)
    print('Extracting download url for', name)
    with urllib.request.urlopen(url) as response:
        body = json.loads(response.read().decode('utf-8'))
        for release in body['releases'].values():
            for source in release:
                if source['filename'] == filename:
                    return source['url']
        else:
            raise Exception('Failed to extract url from {}'.format(url))


def get_file_hash(filename: str) -> str:
    sha = hashlib.sha256()
    print('Generating hash for', filename)
    with open(filename, 'rb') as f:
        while True:
            data = f.read(1024 * 1024 * 32)
            if not data:
                break
            sha.update(data)
        return sha.hexdigest()


package_name = 'python{}-{}'.format('2' if opts.python2 else '3',
                                    opts.packages[0])
tempdir_prefix = 'pip-generator-{}-'.format(package_name)

with tempfile.TemporaryDirectory(prefix=tempdir_prefix) as tempdir:
    if opts.python2:
        pip_executable = 'pip2'
        pip_install_prefix = '--install-option="--prefix=${FLATPAK_DEST}"'
    else:
        pip_executable = 'pip3'
        pip_install_prefix = '--prefix=${FLATPAK_DEST}'

    pip_download = [
        pip_executable,
        'download',
        '--dest',
        tempdir
    ]

    subprocess.run(pip_download + [
        '--no-binary', ':all:',
    ] + opts.packages, check=True)

    pip_command = [
        pip_executable,
        'install',
        '--no-index',
        '--find-links="file://${PWD}"',
        pip_install_prefix,
    ] + [
        shlex.quote(package)
        for package in opts.packages
    ]

    main_module = OrderedDict([
        ('name', package_name),
        ('buildsystem', 'simple'),
        ('build-commands', [' '.join(pip_command)]),
        ('sources', []),
    ])

    if opts.cleanup == 'all':
        main_module['cleanup'] = ['*']
    elif opts.cleanup == 'scripts':
        main_module['cleanup'] = ['/bin', '/share/man/man1']

    for filename in os.listdir(tempdir):
        name = filename.rsplit('-', 1)[0]
        sha256 = get_file_hash(os.path.join(tempdir, filename))
        url = get_pypi_url(name, filename)
        source = OrderedDict([
            ('type', 'file'),
            ('url', url),
            ('sha256', sha256),
        ])
        main_module['sources'].append(source)

output_filename = opts.output or package_name + '.json'
with open(output_filename, 'w') as output:
    output.write(json.dumps(main_module, indent=4))