#!/usr/bin/env bash
###
### a simple complement to bild which only deals with launching repls
###
### > repl [opts] <target..>
###
### Starts a repl/shell for one or more targets. (Currently, all targets must
### have the same extension for this to work.) Repls started with this script
### should bind to `localhost:$PORT`.
###
### Options:
###   --bash   start bash instead of the target language repl
help() {
    sed -rn 's/^### ?//;T;p' "$0"
}
if [[ $# == 0 ]] || [[ "$1" == "-h" ]]; then
    help
    exit 1
fi
##
  set -e
  CMD=
  if [[ "$1" == "--bash" ]]; then
    CMD="bash"
    shift
  fi
  targets=${@:?}
  json=$(bild --json ${targets[@]})
  langdeps=$(jq --raw-output '.[].langdeps | join(" ")' <<< $json)
  sysdeps=$(jq --raw-output '.[].sysdeps | join(" ")' <<< $json)
  exts=$(jq --raw-output '.[].namespace.ext' <<< $json | sort | uniq)
  BILD="(import ${BIZ_ROOT:?}/Biz/Bild.nix {})"
  for lib in ${sysdeps[@]}; do
    flags+=(--packages "$BILD.private.nixpkgs.${lib}")
    flags+=(--packages "$BILD.private.nixpkgs.pkg-config")
  done
  case $exts in
    C)
      flags+=(--packages "$BILD.private.nixpkgs.gcc")
      command="bash"
      ;;
    Hs)
      if [ -z ${var+PORT} ]; then
        echo "warn:  repl:  ghci does not support binding to a port"
      fi
      flags+=(--packages "$BILD.private.ghcWith (h: with h; [$langdeps])")
      command=${CMD:-"ghci -i${BIZ_ROOT:?} -ghci-script ${BIZ_ROOT:?}/.ghci ${targets[@]}"}
      ;;
    Scm)
      for lib in ${langdeps[@]}; do
        flags+=(--packages "$BILD.private.nixpkgs.guile-${lib}")
      done
      flags+=(--packages "$BILD.private.nixpkgs.guile")
      command=${CMD:-"guile -L ${BIZ_ROOT:?} -C ${BIZ_ROOT:?}/_/int --r7rs --listen=${PORT:-37146}"}
      ;;
    Lisp)
      flags+=(--packages "$BILD.private.sbclWith (p: with p; [asdf swank $langdeps])")
      command=${CMD:-"sbcl --eval '(require :asdf)' --eval '(require :swank)' --eval '(swank:create-server :port ${PORT:-4005})' --load $targets"}
      ;;
    Rs)
      flags+=(--packages "$BILD.private.nixpkgs.rustc")
      command=bash
      ;;
    *)
      echo "unsupported targets: ${targets[@]}"
      exit 1
      ;;
  esac
##
  nix-shell "${flags[@]}" --command "$command"
##