import subprocess, re, os, tempfile

class GitError(Exception):
    pass
class SHAError(GitError):
    pass
class ExecutionError(GitError):
    def __init__(self, errcode):
        self.error_code = errcode

def _check(process):
    if process.returncode != 0:
        raise ExecutionError(process.returncode)

_sha_re = re.compile('^[0-9a-fA-F]*$')

def rev_parse(rev='HEAD', tree=None):
    process = subprocess.Popen(['git', 'rev-parse', rev],
                               stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                               close_fds=True, universal_newlines=True, cwd=tree)
    stdout = process.communicate()[0]
    process.wait()
    _check(process)

    sha = stdout.strip()
    if not _sha_re.match(sha):
        raise SHAError()
    return sha

def clean(tree=None):
    cmd = ['git', 'clean', '-f', '-x', '-d', '-q']

    process = subprocess.Popen(cmd,
                               stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                               close_fds=True, universal_newlines=True, cwd=tree)
    stdout = process.communicate()[0]
    process.wait()
    _check(process)

def fetch(tree=None):
    cmd = ['git', 'fetch']

    process = subprocess.Popen(cmd, cwd=tree)
    process.wait()
    _check(process)

def status(tree=None):
    '''
    For interpretation of the porcelain output refer to
    the git status(1) man page. In summary the first column is the
    index state, the second represents the working tree state and
    the third column are files in cases of renames. This gives back
    None in case no changes are present, otherwise it returns a list
    of dict entries with key values: index, work_tree, and files. The
    files are a list of all files found on that entry, in case of a rename
    this would consist of a list of 2 files.

    As an example if you had this on your git status:

    R  udev/foo.sh -> poo/foo.sh
    D  scripts/bar.sh
    ?? .poo.py.swp

    This would be transposed into the following dict:

        results = status(tree=your_git_tree_path)
        if not results:
            return 0
        for entry in results:
            print entry

    {'files': [' udev/foo.sh', 'poo/foo.sh'], 'index': 'R', 'work_tree': ' '}
    {'files': [' scripts/bar.sh'], 'index': 'D', 'work_tree': ' '}
    {'files': [' .poo.py.swp'], 'index': '?', 'work_tree': '?'}
    '''
    def split_status(entry):
        if len(entry) == 0:
            return None
        if len(entry) == 1:
            return dict(index=entry[0], work_tree=None, files=None)
        if len(entry) == 2:
            return dict(index=entry[0], work_tree=entry[1], files=None)
        else:
            return dict(index=entry[0], work_tree=entry[1],
                        files=entry[2:].split(' -> '))

    cmd = ['git', 'status', '--porcelain']

    process = subprocess.Popen(cmd,
            stdout=subprocess.PIPE, stderr=subprocess.STDOUT, close_fds=True,
            universal_newlines=True, cwd=tree)
    stdout = process.communicate()[0]
    process.wait()
    _check(process)

    list_status = stdout.split('\n')
    if (len(list_status) == 1 and list_status[0] == ''):
        return None
    return [split_status(entry) for entry in list_status]

def describe(rev='HEAD', tree=None, extra_args=[]):
    cmd = ['git', 'describe', '--always']

    cmd.extend(extra_args)
    if rev is not None:
        cmd.append(rev)

    process = subprocess.Popen(cmd,
                               stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                               close_fds=True, universal_newlines=True, cwd=tree)
    stdout = process.communicate()[0]
    process.wait()
    _check(process)

    return stdout.strip()

def verify(git_tree):
    tag = describe(rev=None, tree=git_tree, extra_args=['--dirty'])
    cmd = ['git', 'tag', '-v', tag]

    process = subprocess.Popen(cmd,
                               stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                               close_fds=True, universal_newlines=True, cwd=git_tree)
    stdout = process.communicate()[0]
    process.wait()

    return dict(r=process.returncode, output=stdout)

def paranoia(tree):
    clean(tree)
    poo = status(tree)
    if (poo):
        return dict(r=-1, output=poo)
    return verify(tree)

def init(tree=None):
    process = subprocess.Popen(['git', 'init'],
                               stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                               close_fds=True, universal_newlines=True, cwd=tree)
    stdout = process.communicate()[0]
    process.wait()
    _check(process)

def add(path, tree=None):
    process = subprocess.Popen(['git', 'add', '--ignore-removal', path],
                               stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                               close_fds=True, universal_newlines=True, cwd=tree)
    stdout = process.communicate()[0]
    process.wait()
    _check(process)

def commit_all(message, tree=None):
    add('.', tree=tree)
    process = subprocess.Popen(['git', 'commit', '--allow-empty', '-a', '-m', message],
                               stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                               close_fds=True, universal_newlines=True, cwd=tree)
    stdout = process.communicate()[0]
    process.wait()
    _check(process)

def ls_tree(rev, files, tree=None):
    process = subprocess.Popen(['git', 'ls-tree', '-z', '-r', rev, '--', ] + list(files),
                               stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                               close_fds=True, universal_newlines=True, cwd=tree)
    stdout = process.communicate()[0]
    files = stdout.split('\0')
    ret = []
    for f in files:
        if not f:
            continue
        meta, f = f.split('\t', 1)
        meta = meta.split()
        meta.append(f)
        ret.append(meta)
    process.wait()
    _check(process)
    return ret

def get_blob(blob, outf, tree=None):
    try:
        import git, gitdb
        r = git.Repo(path=tree)
        b = r.rev_parse(blob + '^{blob}')
        b.stream_data(outf)
    except ImportError:
        process = subprocess.Popen(['git', 'show', blob],
                                   stdout=outf, close_fds=True, cwd=tree)
        process.wait()
        _check(process)

def clone(gittree, outputdir, options=[]):
    process = subprocess.Popen(['git', 'clone'] + options + [gittree, outputdir])
    process.wait()
    _check(process)

def set_origin(giturl, gitdir):
    process = subprocess.Popen(['git', 'remote', 'rm', 'origin'],
                               close_fds=True, universal_newlines=True, cwd=gitdir)
    process.wait()

    process = subprocess.Popen(['git', 'remote', 'add', 'origin', giturl],
                               close_fds=True, universal_newlines=True, cwd=gitdir)
    process.wait()
    _check(process)

def remote_update(gitdir):
    process = subprocess.Popen(['git', 'remote', 'update'],
                               close_fds=True, universal_newlines=True, cwd=gitdir)
    process.wait()
    _check(process)

def shortlog(from_commit, to_commit, tree=None):
    process = subprocess.Popen(['git', 'shortlog', from_commit + '..' + to_commit],
                               stdout=subprocess.PIPE, stderr=subprocess.PIPE,
                               close_fds=True, universal_newlines=True,
                               cwd=tree)
    stdout = process.communicate()[0]
    process.wait()
    _check(process)
    return stdout

def commit_env_vars(commitid, tree=None):
    process = subprocess.Popen(['git', 'show', '--name-only',
                                '--format=format:GIT_AUTHOR_NAME=%an%nGIT_AUTHOR_EMAIL=%ae%nGIT_AUTHOR_DATE=%aD%x00',
                                commitid],
                                stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                                close_fds=True, universal_newlines=True,
                                cwd=tree)
    stdout = process.communicate()[0]
    process.wait()
    _check(process)
    data = stdout.split('\x00')[0]
    vals = data.split('\n')
    d = {}
    for k, v in map(lambda x: x.split('=', 1), vals):
        d[k] = v
    return d

def commit_message(commitid, tree=None):
    process = subprocess.Popen(['git', 'show', '--name-only',
                                '--format=format:%s%n%n%b%x00', commitid],
                                stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                                close_fds=True, universal_newlines=True,
                                cwd=tree)
    stdout = process.communicate()[0]
    process.wait()
    _check(process)
    return stdout.split('\x00')[0]

def remove_config(cfg, tree=None):
    process = subprocess.Popen(['git', 'config', '--unset-all', cfg],
                               close_fds=True, universal_newlines=True, cwd=tree)
    process.wait()
    _check(process)

def ls_remote(branch, tree=None, remote='origin'):
    process = subprocess.Popen(['git', 'ls-remote', '--exit-code', remote, 'refs/heads/' + branch],
                               stdout=subprocess.PIPE,
                               close_fds=True, universal_newlines=True, cwd=tree)
    stdout = process.communicate()[0]
    process.wait()
    _check(process)
    sha = stdout.split()[0]
    if not _sha_re.match(sha):
        raise SHAError()
    return sha

def add(fn, tree=None):
    process = subprocess.Popen(['git', 'add', '--ignore-removal', fn], cwd=tree,
                               close_fds=True, universal_newlines=True)
    process.wait()
    _check(process)

def commit(msg, tree=None, env = {}, opts=[]):
    stdin = tempfile.NamedTemporaryFile(mode='wr')
    stdin.write(msg)
    stdin.seek(0)
    process = subprocess.Popen(['git', 'commit', '--file=-'] + opts,
                               stdin=stdin.file, universal_newlines=True, env=env,
                               cwd=tree)
    process.wait()
    _check(process)

def push(opts=[], tree=None):
    process = subprocess.Popen(['git', 'push'] + opts,
                               close_fds=True, universal_newlines=True, cwd=tree)
    process.wait()
    _check(process)

def log_commits(from_commit, to_commit, tree=None):
    process = subprocess.Popen(['git', 'log', '--first-parent', '--format=format:%H',
                                from_commit + '..' + to_commit],
                               stdout=subprocess.PIPE,
                               close_fds=True, universal_newlines=True,
                               cwd=tree)
    stdout = process.communicate()[0]
    process.wait()
    _check(process)
    vals = stdout.split()
    vals.reverse()
    return vals

def commit_env_vars(commitid, tree=None):
    process = subprocess.Popen(['git', 'show', '--name-only',
                                '--format=format:GIT_AUTHOR_NAME=%an%nGIT_AUTHOR_EMAIL=%ae%nGIT_AUTHOR_DATE=%aD%x00',
                                commitid],
                                stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                                close_fds=True, universal_newlines=True,
                                cwd=tree)
    stdout = process.communicate()[0]
    process.wait()
    _check(process)
    data = stdout.split('\x00')[0]
    vals = data.split('\n')
    d = {}
    for k, v in map(lambda x: x.split('=', 1), vals):
        d[k] = v
    return d

def rm(opts=[], tree=None):
    process = subprocess.Popen(['git', 'rm'] + opts,
                               close_fds=True, universal_newlines=True, cwd=tree)
    process.wait()
    _check(process)

def reset(opts=[], tree=None):
    process = subprocess.Popen(['git', 'reset'] + opts,
                               close_fds=True, universal_newlines=True, cwd=tree)
    process.wait()
    _check(process)

def diff(tree=None, extra_args=None):
    cmd = ['git', 'diff', '--color=always'] + extra_args

    process = subprocess.Popen(cmd,
                               stdout=subprocess.PIPE, stderr=subprocess.STDOUT,
                               close_fds=True, universal_newlines=True, cwd=tree)
    stdout = process.communicate()[0]
    process.wait()
    _check(process)

    return stdout