#!/usr/bin/env python3

# python deps: requests, pyyaml
# non-python deps: aria2, git

import os
import pathlib
import requests
import subprocess
import yaml


class StackageSession(object):
    def __init__(self):
        self._base_path = pathlib.Path(os.environ['TUNASYNC_WORKING_DIR'])

    def download(self, dir_, url, sha1=None, force=False):
        dir_path = self._base_path / dir_
        file_path = dir_path / url.split('/')[-1]
        if force and file_path.is_file():
            file_path.unlink()
        if file_path.is_file():
            print('{} exists, skipping'.format(file_path))
        else:
            args = ['aria2c', url, '--dir={}'.format(dir_path)]
            if sha1:
                args.append('--checksum=sha-1={}'.format(sha1))
            if subprocess.run(args).returncode != 0 and file_path.is_file():
                file_path.unlink()
                raise OSError('Download failed for {}'.format(url))
            else:
                print('Downloaded {} to {}'.format(url, file_path))

    def load_stack_setup(self):
        d = yaml.load(requests.get(
            'https://raw.githubusercontent.com/fpco/stackage-content/master/stack/stack-setup-2.yaml').content)
        for platform in d['ghc']:
            for ver in d['ghc'][platform]:
                self.download('ghc', d['ghc'][platform][ver]['url'], d['ghc'][platform][ver]['sha1'])
                d['ghc'][platform][ver]['url'] = 'http://mirrors.tuna.tsinghua.edu.cn/stackage/ghc/{}'.format(
                    d['ghc'][platform][ver]['url'].split('/')[-1])
        d['msys2'] = {'windows32': {'version': '20161025',
                                    'url': 'http://mirrors.tuna.tsinghua.edu.cn/msys2/distrib/i686/msys2-base-i686-20161025.tar.xz',
                                    'content-length': 47526500,
                                    'sha1': '5D17FA53077A93A38A9AC0ACB8A03BF6C2FC32AD'},
                      'windows64': {'version': '20161025',
                                    'url': 'http://mirrors.tuna.tsinghua.edu.cn/msys2/distrib/x86_64/msys2-base-x86_64-20161025.tar.xz',
                                    'content-length': 47166584,
                                    'sha1': '05FD74A6C61923837DFFE22601C9014F422B5460'}}
        with open(self._base_path / 'stack-setup.yaml', 'w') as f:
            yaml.dump(d, f)
        print('Loaded stack-setup.yaml')

    def load_stackage_snapshots(self):
        for channel in ['lts-haskell', 'stackage-nightly']:
            if (self._base_path / channel).is_dir():
                args = ['git', '-C', self._base_path / channel, 'pull']
            else:
                args = ['git', '-C', self._base_path, 'clone', '--depth', '1',
                        'https://github.com/fpco/{}.git'.format(channel)]
            subprocess.run(args, check=True)
            print('Loaded {}'.format(channel))
        self.download('', 'https://www.stackage.org/download/snapshots.json', force=True)
        print('Loaded snapshots.json')


if __name__ == '__main__':
    s = StackageSession()
    s.load_stackage_snapshots()
    s.load_stack_setup()