remote-helpers: add testgit helper

Currently the remote helper infrastructure is only used by the curl
helper, which does not give a good impression of how remote helpers
can be used to interact with foreign repositories. Since implementing
such a helper is non-trivial it would be good to have at least one
easy-to-follow example demonstrating how to implement a helper that
interacts with a foreign vcs using fast-import/fast-export.

The testgit helper can be used to interact with remote git
repositories by prefixing the url with "testgit::".

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 70 insertions, 0 deletions

diff --git a/git_remote_helpers/git/repo.py b/git_remote_helpers/git/repo.py
new file mode 100644
index 000000000..82d5f78c7
--- /dev/null
+++ b/git_remote_helpers/git/repo.py
@@ -0,0 +1,70 @@
+import os
+import subprocess
+
+def sanitize(rev, sep='\t'):
+    """Converts a for-each-ref line to a name/value pair.
+    """
+
+    splitrev = rev.split(sep)
+    branchval = splitrev[0]
+    branchname = splitrev[1].strip()
+    if branchname.startswith("refs/heads/"):
+        branchname = branchname[11:]
+
+    return branchname, branchval
+
+def is_remote(url):
+    """Checks whether the specified value is a remote url.
+    """
+
+    prefixes = ["http", "file", "git"]
+
+    return any(url.startswith(i) for i in prefixes)
+
+class GitRepo(object):
+    """Repo object representing a repo.
+    """
+
+    def __init__(self, path):
+        """Initializes a new repo at the given path.
+        """
+
+        self.path = path
+        self.head = None
+        self.revmap = {}
+        self.local = not is_remote(self.path)
+
+        if(self.path.endswith('.git')):
+            self.gitpath = self.path
+        else:
+            self.gitpath = os.path.join(self.path, '.git')
+
+        if self.local and not os.path.exists(self.gitpath):
+            os.makedirs(self.gitpath)
+
+    def get_revs(self):
+        """Fetches all revs from the remote.
+        """
+
+        args = ["git", "ls-remote", self.gitpath]
+        path = ".cached_revs"
+        ofile = open(path, "w")
+
+        subprocess.check_call(args, stdout=ofile)
+        output = open(path).readlines()
+        self.revmap = dict(sanitize(i) for i in output)
+        if "HEAD" in self.revmap:
+            del self.revmap["HEAD"]
+        self.revs = self.revmap.keys()
+        ofile.close()
+
+    def get_head(self):
+        """Determines the head of a local repo.
+        """
+
+        if not self.local:
+            return
+
+        path = os.path.join(self.gitpath, "HEAD")
+        head = open(path).readline()
+        self.head, _ = sanitize(head, ' ')