#!/usr/bin/env nix-shell
#!nix-shell -i bash -p nettools

SELF=$(hostname)

usage() {
  echo "deploy: deploy a nix config to a remote machine, possibly activating it"
  echo ""
  echo "usage: deploy [options] [host] [host2 ...]"
  echo "options:"
  echo "- --action copy|switch|test   (default: 'switch')"
  echo "- --variant light|min|''|all  (default: '')"
  echo "- --pre: alias for --action copy --variant all all"
  echo ""
  echo "common idioms:"
  echo "- deploy all: deploy all hosts, sequentially"
  echo "- deploy --pre: build and copy all hosts"
  exho "- deploy desko lappy: build and deploy just those hosts"
  echo "- deploy: deploy the local host"
  exit 1
}

info() {
  echo "[deploy]" "$@"
}

action=switch
hosts=()
defaultHost="$SELF"
variants=()
defaultVariant=
nixArgs=()
addHost() {
  if [ "$1" = all ]; then
    # order matters:
    hosts+=(moby lappy desko servo crappy)
  else
    hosts+=("$1")
  fi
}
addVariant() {
  if [ "$1" = all ]; then
    variants+=("-min" "-light" "" "-min-next" "-light-next" "-next")
  elif [ -n "$1" ]; then
    variants+=("-$1")
  else
    # "full" variant
    variants+=("")
  fi
}
parseArgs() {
  while [ "$#" -ne 0 ]; do
    local arg=$1
    shift
    case "$arg" in
      (--action)
        action=$1
        shift
        ;;
      (--help)
        usage
        ;;
      (--variant)
        addVariant "$1"
        shift
        ;;
      (all|crappy|desko|lappy|moby|servo)
        addHost "$arg"
        ;;
      (--pre)
        action=copy
        defaultVariant=all
        defaultHost=all
        ;;
      (*)
        nixArgs+=("$arg")
        ;;
    esac
  done

  if [ "${#hosts[@]}" -eq 0 ] && [ -n "$defaultHost" ]; then
    addHost "$defaultHost"
  fi
  if [ "${#variants[@]}" -eq 0 ]; then
    addVariant "$defaultVariant"
  fi
}

runOnTarget() {
  # run the command ($@) on the machine we're deploying to.
  # if that's a remote machine, then do it via ssh, else local shell.
  if [ -n "$host" ] && [ "$host" != "$SELF" ]; then
    info "running on remote:" "$@"
    ssh "$host" "$@"
  else
    info "running locally:" "$@"
    "$@"
  fi
}

# deployOneHost $host $variant
deployOneHost() {
  local host="$1"
  local variant="$2"

  info "building $host$variant ..."
  nix-build -A "hosts.$host$variant.toplevel" --out-link "./build/result-$host$variant" "${nixArgs[@]}" || return 1
  storePath="$(readlink ./build/result-$host$variant)"
  info "build $host$variant -> $storePath"

  # mimic `nixos-rebuild --target-host`, in effect:
  # - nix-copy-closure ...
  # - nix-env --set ...
  # - switch-to-configuration <boot|dry-activate|switch|test|>
  # avoid the actual `nixos-rebuild` for a few reasons:
  # - fewer nix evals
  # - more introspectability and debuggability
  # - sandbox friendliness (especially: `git` doesn't have to be run as root)

  if [ -n "$host" ] && [ "$host" != "$SELF" ]; then
    if [ -e /run/secrets/nix_signing_key ]; then
      info "signing store paths ..."
      sudo nix store sign -r -k /run/secrets/nix_signing_key "$storePath"
    else
      info "not signing store paths: /run/secrets/nix_signing_key does not exist"
    fi
    # add more `-v` for more verbosity (up to 5).
    # builders-use-substitutes false: optimizes so that the remote machine doesn't try to get paths from its substituters.
    #   we already have all paths here, and the remote substitution is slow to check and SERIOUSLY flaky on moby in particular.
    nix copy -vv --option builders-use-substitutes false --to "ssh-ng://$host" "$storePath" || return 1
  fi

  if [ -n "$action" ] && [ "$action" != "copy" ]; then
    info "activating profile... "
    runOnTarget sudo nix-env -p /nix/var/nix/profiles/system --set "$storePath" || return 1
    runOnTarget sudo "$storePath/bin/switch-to-configuration" "$action" || return 1
  fi
}


parseArgs "$@"

failedDeploys=()
for h in "${hosts[@]}"; do
  for v in "${variants[@]}"; do
    deployOneHost "$h" "$v" || \
      failedDeploys+=("$h$v")
  done
done

if [ "${#failedDeploys[@]}" -ne 0 ]; then
  echo "FAILED DEPLOYMENT:"
  for d in "${failedDeploys[@]}"; do
    echo "- $d"
  done
  exit 1
else
  echo "SUCCESS"
fi