#!/bin/bash
#
# Perform an MK runtime extension, if applicable, and then execute the MK
# client with the same arguments passed to this script.

# Get the extension URL from our configuration parser.  This is not exposed to
# the extended environment, so we can't override how this is discovered in
# this code.  That is probably the biggest limitation of the update system at
# this point in time, but requires moving config parsing logic into this
# script to fix... which is complex, to say the least. ;)
url="$(mk config extend)"

# Configuration-ish constants
livedir='/tmp/mk-update'
varpath='/var/lib/mk-update'
zip="${varpath}/mk-extension.zip"

# Set up the runtime environment.
mkdir -p "${varpath}"

if test -n "${url}"; then
    # Try and download an update from the server.
    if [[ "$(curl "${url}" -z "${zip}" -o "${zip}" -sLw "%{http_code}")" == "200" ]]; then
        # We got an update to the file.  Might have spat out errors about missing
        # zip file for sourcing or whatever, but those don't matter.  What matters
        # is we got a 200 on the download, so we need to bump to a new version of
        # the file.
        tmpdir="$(mktemp -d /tmp/mk-update-$$-XXXXXXXXXX)"
        if unzip -o "${zip}" -d "${tmpdir}"; then
            rm -rf "${livedir}"
            mv "${tmpdir}" "${livedir}"
        else
            # @todo danielp 2014-05-02: log this back to the server
            rm -rf "${tmpdir}"
        fi
    fi
fi

# If we have a live directory, add it to the various environment vars.
if test -d "${livedir}"; then
    export PATH="${livedir}/bin${PATH:+:${PATH}}"
    export LD_LIBRARY_PATH="${livedir}/lib${LD_LIBRARY_PATH:+:${LD_LIBRARY_PATH}}"
    export RUBYLIB="${livedir}/lib/ruby${RUBYLIB:+:${RUBYLIB}}"
    MK_EXTERNAL_FACTS="${livedir}/facts.d"
    test -d "$MK_EXTERNAL_FACTS" && export MK_EXTERNAL_FACTS
fi

# Finally, execute the MK client in our new post-update environment.
exec mk "$@"