monitor.sh

#!/bin/sh

set -eux

dbg() {
    echo "$@" >&2
}

readonly CHAN="#christensen-test"
readonly URL="https://channels.nix.gsc.io"
readonly remote="origin"
readonly gitrepo="$1"
readonly dest="$2"

(
    cd "$gitrepo" >&2
    git fetch "$remote"  >&2
    git for-each-ref --format '%(refname:strip=3)' \
        "refs/remotes/$remote"
) | grep -v HEAD |
    (
        cd "$dest"
        touch summary
        echo -n "" > summary
        summary="$(pwd)/summary"
        while read -r branch; do
            name=$(echo "$branch" | sed -e "s#/#_#g" -e "s#\.\.#_#g")
            mkdir -p "$name"
            (
                cd "$name"
                touch latest
                (
                    cd "$gitrepo" >&2
                    git show -s --format="%H %at" "$remote/$branch"
                ) > latest.next
                if [ "$(md5sum < latest.next)" != "$(md5sum < latest)" ]; then
                    dbg "Change in ${branch}"
                    (
                        cd "$gitrepo" >&2
                        echo -n "Channel $branch advanced to "
                        git show -s --format="https://github.com/NixOS/nixpkgs/commit/%H (from %cr, history: $URL/$name/history)" "$remote/$branch"
                    ) >> "$summary"
                    mv latest.next latest
                    chmod a+r latest
                    touch history
                    (
                        cat history
                        cat latest
                    ) | tail -n10000 > history.next
                    mv history.next history
                    chmod a+r history
                else
                    dbg "No change in ${branch}"
                    rm latest.next
                fi
            )
        done

        if [ $(wc -l "$summary" | cut -d' ' -f1) -gt 0 ]; then
            (
                sleep 5
                echo 'NICK testbot'
                sleep 2
                echo 'USER testbot 0 * :testbot'
                sleep 2
                echo "JOIN :$CHAN"
                sleep 10
                cat "$summary" | sed -e "s/^/NOTICE $CHAN :/"
                sleep 3
                echo "QUIT :Info at $URL"
                sleep 5
            ) | telnet irc.freenode.net 6667 || true
        fi

        rm -f summary
    )