#!/bin/sh

# Run as root
[ "$(id -u)" -eq 0 ] || exec sudo "${0}" "${@}"
cd "$(dirname "${0}")"

[ "${1}" = "-n" ] && NO_SYNC=true

meh() { printf " \033[1;32m*\033[0m %s\n" "${*}"; }
omg() { printf " \033[1;33m*\033[0m %s\n" "${*}"; }
wtf() { printf " \033[1;31m*\033[0m %s\n" "${*}"; kill $$; exit 1; }

sync="rsync://paka/freebsd-ports"

sync_opts="--archive --compress --delete --hard-links --sparse --stats --verbose"

zpool="amani"

ports=${zpool}/ports
upstream=${zpool}/srcs/freebsd/ports/upstream
prepare=${zpool}/srcs/freebsd/ports/prepare

today="$(date +%Y-%m-%d)"
upstream_fs="$(zfs get -H -o value mountpoint "${upstream}")"

# Check if target ports tree actually exists; otherwise, assume it's safe to replace
if zfs list "${ports}" >&- 2>&-
then
  ports_exists="YES"
  ports_origin="$(zfs get -H -o value origin "${ports}")"
  ports_origin="${ports_origin%%@*}"
  ports_fs="$(zfs get -H -o value mountpoint "${ports}")"

  # Make sure the ports tree is a descendent of the ports upstream
  [ "${ports_origin}" = "${upstream}" ] || wtf "Target ${ports} is not a child of ${upstream}
  (is ${ports_origin})"
fi
ports_fs="${ports_fs:-/usr/ports}"

if [ -z "${NO_SYNC}" ]
then
  # Compute the next available snapshot
  last_snapshot="$(zfs list -rHt snapshot -o name "${upstream}" | grep "@${today}_" | sort | tail -n 1 | sed -e 's/^.*_\([0-9]\{2\}\)$/\1/')"
  if [ "${last_snapshot}" ]
  then
    snapshot="$(printf "${today}_%02u" "$(( ${last_snapshot} + 1 ))")"
    echo "${today}_${last_snapshot} -> ${snapshot}"
  else
    snapshot="${today}_00"
    echo "None -> ${snapshot}"
  fi
else
  # Don't bother creating a new snapshot if the tree will not be synchronized
  last_snapshot="$(zfs list -rHt snapshot -o name "${upstream}" | sort | tail -n 1)"
  snapshot="${last_snapshot##*@}"
  echo "Using existing snapshot ${snapshot}"
fi

# Bail out if anything is /
[ -z "${ports_fs}" ] && wtf "ports_fs is / ?!"
[ -z "${upstream_fs}" ] && wtf "upstream_fs is / ?!"
[ -z "${ports_fs}"  -o -z "${upstream_fs}" ] && wtf "Writing to /? Are you nuts?"

if [ -z "${NO_SYNC}" ]
then
  meh "Update"
  rsync ${sync_opts} "${sync}/" "${upstream_fs}/" || wtf "update failed"

  meh "Snapshot"
  zfs snapshot "${upstream}@${snapshot}" || wtf "snapshot failed"
fi

meh "Clone"
zfs clone "${upstream}@${snapshot}" "${prepare}" || wtf "clone failed"
zfs set atime=off "${prepare}" || wtf "atime-off failed"

# Resolve filesystem mountpoints, now that everything should exist
prepare_fs="$(zfs get -H -o value mountpoint "${prepare}")"

meh "Overlay"
( cd ports; find * | cpio -p "${prepare_fs}" ) || wtf "overlay failed"

meh "Patch"
for patch in patch/*.patch
do
  meh "... ${patch}"
  ( cd "${prepare_fs}"; patch -p0 ) < "${patch}" || wtf "patch failed"
done

meh "Install"
zfs set readonly=on "${prepare}" || wtf "readonly failed"
# Half of this is conditional on the old ports tree's existence
[ -z "${ports_exists}" ] || zfs rename "${ports}" "${ports}-bak" || wtf "backup rename failed"
zfs rename "${prepare}" "${ports}" || wtf "rename prepare -> ports failed"
[ -z "${ports_exists}" ] || zfs inherit mountpoint "${ports}-bak" || wtf "inherit failed"
zfs set mountpoint="${ports_fs}" "${ports}" || wtf "mountpoint failed"
[ -z "${ports_exists}" ] || zfs destroy "${ports}-bak" || wtf "destroy failed"

meh "All done"