#!/bin/sh

lock=/tmp/mmg
mkdir "$lock" || exit 1

myexit() {
    rmdir "$lock" 2>/dev/null
    exit "$1"
}

HOME=/home/nsm
. "$HOME/.profile"
export TZ=UTC
d=/dev/shm
read -r ver < "$d/half/uname"

{
    cat <<EOF
# $ver
# /dev/shm and /tmp are tmpfs
# as user, nsm here:
#   touch /dev/shm/mempool.dat.new
# as root:
#   cd /home/nsm/.bitcoin
#   mount -o rw,bind /dev/shm/mempool.dat.new mempool.dat.new
# everything else here that follows
# is run as an unprivileged user
EOF
    set -x
    date -u
    bitcoind -version | head -1
    bitcoin-cli echo hello | grep . || myexit 1
    mountpoint "$HOME/.bitcoin/mempool.dat.new" || myexit 1

    bitcoin-cli getmempoolinfo | nicecat.sh /tmp/gmi-main.json

    : following is getrawmempool, just shortened
    grm.sh | safecat.sh /dev/shm/mymempool.txt

    : Following non-zero exit is intended.
    : On bitcoind side it looks like this:
    :   Failed to dump mempool: Rename failed. Continuing anyway.
    time bitcoin-cli savemempool

    f="$d/mempool.dat.new"

    : Leverage safecat to make a clean, atomic copy of the mempool dump
    cat "$f" | safecat.sh "$d/mempool.copy"

    : Safe symlink update without crashing or throwing an error if it exists
    if test ! -e "$d/mempool.copy.dat"; then
        ln -s "$d/mempool.copy" "$d/mempool.copy.dat"
    fi

    cd "$d"
    ls -ilh mempool.copy mempool.dat.new
    cd "$HOME/web/ln"
    ls -l mymempool*

    date -u
} 2>&1 | nicecat.sh "$d/mymempool.log"

myexit 0