build: create version from git tag

setup.py

@@ -1,11 +1,61 @@
+import os
+import subprocess
+
+from distutils.command.sdist import sdist
+
 from setuptools import find_packages, setup
 
+
+class eo_sdist(sdist):
+    def run(self):
+        if os.path.exists('VERSION'):
+            os.remove('VERSION')
+        version = get_version()
+        with open('VERSION', 'w') as fd:
+            fd.write(version)
+        sdist.run(self)
+        if os.path.exists('VERSION'):
+            os.remove('VERSION')
+
+
+def get_version():
+    """Use the VERSION, if absent generates a version with git describe, if not
+    tag exists, take 0.0- and add the length of the commit log.
+    """
+    if os.path.exists('VERSION'):
+        with open('VERSION') as v:
+            return v.read()
+    if os.path.exists('.git'):
+        p = subprocess.Popen(
+            ['git', 'describe', '--dirty=.dirty', '--match=v*'],
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+        )
+        result = p.communicate()[0]
+        if p.returncode == 0:
+            result = result.decode('ascii').strip()[1:]  # strip spaces/newlines and initial v
+            if '-' in result:  # not a tagged version
+                real_number, commit_count, commit_hash = result.split('-', 2)
+                version = '%s.post%s+%s' % (real_number, commit_count, commit_hash)
+            else:
+                version = result
+            return version
+        else:
+            return '0.0.post%s' % len(subprocess.check_output(['git', 'rev-list', 'HEAD']).splitlines())
+    return '0.0'
+
+
+
+
 setup(
     name='gitea_redmine',
-    version="0.1",
+    version=get_version(),
     description='Micro serveur HTTP pour intercepter les webhooks Gitea et mettre à jour les tickets redmine correspondants avec les bons status / liens vers pull requests.',
     author='Agate Berriot',
     author_email='aberriot@entrouvert.com',
+    cmdclass={
+        'sdist': eo_sdist,
+    },
     packages=find_packages(exclude=['tests']),
     py_modules=['gitea_redmine'],
     include_package_data=True,