ExampleURLProvider.py

import re
import urllib2

from autopkglib import Processor, ProcessorError


__all__ = ["ExampleURLProvider"]


EXAMPLE_BASE_URL = "http://example.com/downloads"
re_dmg = re.compile(r'a[^>]* href="(?P<filename>[^"]+\.dmg)"')


class ExampleURLProvider(Processor):
    description = "Provides URL to the latest Example download."
    input_variables = {
        "base_url": {
            "required": False,
            "description": "Default is '%s." % EXAMPLE_BASE_URL,
        },
    }
    output_variables = {
        "url": {
            "description": "URL to the latest Example product download.",
        },
    }
    
    __doc__ = description
    
    def get_example_dmg_url(self, base_url):
        # Construct download directory URL.
        index_url = base_url
        
        # Read HTML index.
        try:
            f = urllib2.urlopen(index_url)
            html = f.read()
            f.close()
        except BaseException as e:
            raise ProcessorError("Can't download %s: %s" % (index_url, e))
        
        # Search for HTML links that link to files ending in .dmg
        m = re_dmg.search(html)
        if not m:
            raise ProcessorError(
                "Couldn't find download URL in %s" 
                % index_url)
        
        # Return URL.
        return "/".join((base_url, m.group("filename")))
    
    def main(self):
        # Determine base_url.
        base_url = self.env.get("base_url", EXAMPLE_BASE_URL)
        
        self.env["url"] = self.get_example_dmg_url(base_url)
        self.output("Found URL %s" % self.env["url"])


if __name__ == "__main__":
    processor = ExampleURLProvider()
    processor.execute_shell()