setup.py: Integrate C++/usvg install

setup.py

@@ -1,12 +1,106 @@
 #!/usr/bin/env python3
 
+import os
+import sys
 from setuptools import setup
+from setuptools.command.install import install
+import subprocess
+from multiprocessing import cpu_count
+from pathlib import Path
 
 def readme():
     with open('README.rst') as f:
         return f.read()
 
+
+def get_virtualenv_path():
+    """Used to work out path to install compiled binaries to."""
+    if hasattr(sys, 'real_prefix'):
+        return sys.prefix
+
+    if hasattr(sys, 'base_prefix') and sys.base_prefix != sys.prefix:
+        return sys.prefix
+
+    if 'conda' in sys.prefix:
+        return sys.prefix
+
+    return '/usr/local'
+
+def compile_and_install_svgflatten():
+    src_path = 'svg-flatten'
+
+    try:
+        subprocess.run(['make', 'check-deps'], cwd=src_path, check=True)
+        subprocess.run(['make', '-j', str(cpu_count()), 'all'], cwd=src_path, check=True)
+        subprocess.run(['make', 'install', f'PREFIX={get_virtualenv_path()}'], cwd=src_path, check=True)
+    except subprocess.CalledProcessError:
+        print('Error building svg-flatten C++ binary. Please see log above for details.', file=sys.stderr)
+        sys.exit(1)
+
+def has_usvg():
+    checks = ['usvg', str(Path.home() / '.cargo' / 'bin' / 'usvg')]
+    if 'USVG' in os.environ:
+        checks = [os.environ['USVG'], *checks]
+
+    for check in checks:
+        try:
+            subprocess.run(['usvg'], capture_output=True)
+            return True
+
+        except FileNotFoundError:
+            pass
+
+    else:
+        return False
+
+def install_usvg():
+    try:
+        subprocess.run(['cargo'], check=True, capture_output=True)
+
+    except subprocess.CalledProcessError as e:
+        if b'no default toolchain set' in e.stderr:
+            print('No rust installation found. Calling rustup.')
+
+            try:
+                subprocess.run(['rustup', 'install', 'stable'], check=True)
+                subprocess.run(['rustup', 'default', 'stable'], check=True)
+
+            except subprocess.FileNotFoundError as e:
+                print('Cannot find rustup executable. svg-flatten needs usvg, which we install via rustup. Please install rustup or install usvg manually.', file=sys.stderr)
+                sys.exit(1)
+
+            except subprocess.CalledProcessError as e:
+                print('Error installing usvg:', e.returncode, file=sys.stderr)
+                sys.exit(1)
+
+        else:
+            print('Error installing usvg:', e.returncode, file=sys.stderr)
+            print(e.stdout.decode())
+            print(e.stderr.decode())
+            sys.exit(1)
+
+    except subprocess.FileNotFoundError as e:
+        print('Cannot find cargo executable. svg-flatten needs usvg, which we install via cargo. Please install cargo or install usvg manually.', file=sys.stderr)
+        sys.exit(1)
+
+    try:
+        subprocess.run(['cargo', 'install', 'usvg'], check=True)
+
+    except subprocess.CalledProcessError as e:
+        print('Error installing usvg:', e.returncode, file=sys.stderr)
+        sys.exit(1)
+
+class CustomInstall(install):
+    """Custom handler for the 'install' command."""
+    def run(self):
+        compile_and_install_svgflatten()
+        if not has_usvg():
+            print('usvg not found. Installing.')
+            install_usvg()
+        super().run()
+
 setup(
+    cmdclass={'install': CustomInstall},
     name = 'gerbolyze',
     version = '2.0.0',
     py_modules = ['gerbolyze'],
@@ -40,3 +134,4 @@ setup(
         'Topic :: Utilities'
         ]
 )
+