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import urllib2

from webkitpy.tool.steps.abstractstep import AbstractStep
from webkitpy.tool.steps.options import Options
from webkitpy.common.config import urls
from webkitpy.common.system.deprecated_logging import log, error


class UpdateChromiumDEPS(AbstractStep):
    @classmethod
    def options(cls):
        return AbstractStep.options() + [
            Options.non_interactive,
        ]

    # Notice that this method throws lots of exciting exceptions!
    def _fetch_last_known_good_revision(self):
        return int(urllib2.urlopen(urls.chromium_lkgr_url).read())

    def _validate_revisions(self, current_chromium_revision, new_chromium_revision):
        if new_chromium_revision < current_chromium_revision:
            message = "Current Chromium DEPS revision %s is newer than %s." % (current_chromium_revision, new_chromium_revision)
            if self._options.non_interactive:
                error(message)  # Causes the process to terminate.
            log(message)
            new_chromium_revision = self._tool.user.prompt("Enter new chromium revision (enter nothing to cancel):\n")
            try:
                new_chromium_revision = int(new_chromium_revision)
            except ValueError, TypeError:
                new_chromium_revision = None
            if not new_chromium_revision:
                error("Unable to update Chromium DEPS")


    def run(self, state):
        # Note that state["chromium_revision"] must be defined, but can be None.
        new_chromium_revision = state["chromium_revision"]
        if not new_chromium_revision:
            new_chromium_revision = self._fetch_last_known_good_revision()

        deps = self._tool.checkout().chromium_deps()
        current_chromium_revision = deps.read_variable("chromium_rev")
        self._validate_revisions(current_chromium_revision, new_chromium_revision)
        log("Updating Chromium DEPS to %s" % new_chromium_revision)
        deps.write_variable("chromium_rev", new_chromium_revision)
