#!/bin/bash

set -e

emsg() {
  >&2 echo "garlicd: $@"
}

msg() {
  emsg "$@"
  if [ ! -z "$st" ]; then echo "garlicd: $@" >>"$st"; fi
}

if [ ! -z "$1" ]; then
  >&2 echo "usage: garlicd"
  exit 1
fi

export PATH="@extraPath@:$PATH"

garlic_sandbox=$(nix show-config |\
  grep extra-sandbox-paths |\
  grep -o '/garlic=[^ ]*' || true)

if [ -z "$garlic_sandbox" ]; then
  emsg "Missing extra-sandbox-paths /garlic mountpoint"
  emsg "Check the ~/.config/nix/nix.conf file"
  exit 1
fi

mountdir_rel=$(echo "$garlic_sandbox" | sed 's@^/garlic=@@g')
mountdir=$(readlink -f "$mountdir_rel")
run="$mountdir/run"
completed="$mountdir/completed"
wipe="$mountdir/wipe"
st="$mountdir/st"

handle_bad_signal() {
  msg "cleaning FIFO pipes"
  rm -f "$run" "$completed" "$wipe"
  exit 1
}

trap handle_bad_signal SIGINT

for fifo in "$run" "$completed" "$wipe"; do
  if [ ! -e "$fifo" ]; then
    mkfifo "$fifo"
    # FIXME: Use more resctrictive permissions
    chmod 666 "$fifo"
  fi
done

while true; do
  emsg "--- Waiting for experiments ---"
  tre=$(head -1 "$run")

  # Truncate state file
  printf "" > "$st"

  msg "Attempting to run: $tre"
  msg "Copying files to MN4..."
  # It fails if the user doesn't have nix-store, but is already copied
  # with the post build hook
  nix copy --to ssh://mn1 $tre || true

  set +e

  msg "Launching the experiment..."
  garlic -R "$tre" 2>>"$st"
  if [ "$?" != 0 ]; then
    echo ERROR > "$completed"
    msg "Failed to run the experiment :-("
    continue
  fi

  msg "Fetching results..."
  garlic -FKv "$tre" 2>>"$st"

  if [ "$?" != 0 ]; then
    echo ERROR > "$completed"
    msg "The experiment failed :-("
    continue
  fi

  set -e

  msg "Signalling nix build..."
  echo -n "$tre" >> "$completed"

  msg "Waiting for nix to finish the build..."

  tre2=$(head -1 "$wipe")
  if [ "$tre" != "$tre2" ]; then
    msg "error: trebuchet mismatch"
    exit 1
  fi

  msg "Removing temporal files..."
  garlic -D "$tre" 2>>"$st"

  echo -n "$tre" >> "$completed"

  msg "Execution completed :-)"
done