#!/bin/sh -eu

# Very quick and simple "configure" script for the debugger, ocamlbuild and
# ocamldoc.
# Arguments:
#  $1: tool to configure for: "debugger", "ocamlbuild" or "ocamldoc"
# Environment variables:
#  UNINSTALLED_OCAML_DESTDIR: see below
#  UNINSTALLED_OCAML_PREFIX: see below

TOOL="${1:="none"}"

# Configuration from the user through environment variables:
# - UNINSTALLED_OCAML_DESTDIR: if the OCaml compiler has been installed
#   temporarily, the location it has been installed to.
# - UNINSTALLED_OCAML_PREFIX: the -prefix used for the ocaml compilation; only
#   used if UNINSTALLED_OCAML_PREFIX is set.

: ${UNINSTALLED_OCAML_DESTDIR:=""}
: ${UNINSTALLED_OCAML_PREFIX:=/usr/local}


# Helper functions

# test_ocaml_tool: test that the command named "$1" and provided as "$2" runs;
# this is a simple test which runs "$1 -version 2>/dev/null >/dev/null".
test_ocaml_tool() {
  local NAME="${1}" # This is only used to give a better error message
  local COMMAND="${2}"

  if ${COMMAND} -version 2>/dev/null >/dev/null; then
    echo "${COMMAND}"
  else
    echo "Couldn't find a way to invoke '${NAME}'." 1>&2
  fi
}

# bytecode_or_native: turn the command name provided through "$1" into a
# command to invoke it, either by prepending ${OCAMLRUN} or by appending .opt
# (basically).
bytecode_or_native() {
  local EXECUTABLE="${1}"

  if [ -z "${OPT}" ]; then
    test_ocaml_tool "${EXECUTABLE}" "${OCAMLRUN}${U_BINDIR}${EXECUTABLE}"
  else
    test_ocaml_tool "${EXECUTABLE}" "${U_BINDIR}${EXECUTABLE}.opt"
  fi
}

# Test the given code in the toplevel; useful to check that a given
# functionality is available.
test_in_toplevel() {
  CODE="${1}"
  MODULES="${2}"
  (
    export CAML_LD_LIBRARY_PATH=${CAML_LD_LIBRARY_PATH}
    printf "${CODE}" | ${OCAML} ${MODULES} >/dev/null
  )
}


# Body

if [ -n "${UNINSTALLED_OCAML_DESTDIR}" ]; then
  U_BINDIR="${UNINSTALLED_OCAML_DESTDIR}/${UNINSTALLED_OCAML_PREFIX}/bin/"
else
  U_BINDIR=""
fi

# Determine whether we can use .opt binaries for the compilation; the test is
# fairly simple but should cover > 95% of uses and since it's only a speed
# improvement it doesn't have to be perfect.
# NOTE: if your .opt binaries don't work for one reason or another, simply run
#       "chmod -x" on (one of) them.
if [ -x "${U_BINDIR}ocamlc.opt" ] && [ -x "${U_BINDIR}ocamlopt.opt" ]; then
  echo "Will use .opt binaries."
  OPT=".opt"
else
  echo "Will not use .opt binaries."
  OPT=""
fi

: ${OCAMLRUN:="${U_BINDIR}ocamlrun "}
: ${OCAML:="${OCAMLRUN}${U_BINDIR}ocaml"}
: ${OCAMLC:="$(bytecode_or_native ocamlc)"}
: ${OCAMLOPT:="$(bytecode_or_native ocamlopt)"}
: ${OCAMLLEX:="$(bytecode_or_native ocamllex)"}
: ${OCAMLDEP:="$(bytecode_or_native ocamldep)"}
: ${OCAMLYACC:="${U_BINDIR}ocamlyacc"}
: ${OCAMLDOC_RUN:="${OCAMLRUN}./ocamldoc"}

if [ -z "${OCAMLC}" ] || [ -z "${OCAMLLEX}" ] || [ -z "${OCAMLDEP}" ]; then
  printf '\nERROR: some required tools were not found.\n\n' 1>&2
  exit 1
fi

# If the compiler is in an uninstalled state, we need to invoke it with
# "-nostdlib -I $DESTDIR/$LIBDIR" so determine that. It will also be useful for
# the Makefile "include" directive.
LIBDIR="$(${OCAMLC} -config | awk -F' ' '/^standard_library_default: / { print $2; }')"
if [ -z "${UNINSTALLED_OCAML_DESTDIR}" ]; then
  CLFLAGS="-I +compiler-libs"
  OCAML_MAKEFILE_CONFIG="${LIBDIR}/Makefile.config"
  CAML_LD_LIBRARY_PATH=""
else
  CLFLAGS="-nostdlib -I ${UNINSTALLED_OCAML_DESTDIR}/${LIBDIR} -I ${UNINSTALLED_OCAML_DESTDIR}/${LIBDIR}/compiler-libs"
  OCAML_MAKEFILE_CONFIG="${UNINSTALLED_OCAML_DESTDIR}/${LIBDIR}/Makefile.config"
  CAML_LD_LIBRARY_PATH="${UNINSTALLED_OCAML_DESTDIR}/${LIBDIR}/stublibs"
fi

# Now that we have the compiler and linker search flags, append them.
OCAML="${OCAML} ${CLFLAGS}"
OCAMLC="${OCAMLC} ${CLFLAGS}"
OCAMLOPT="${OCAMLOPT} ${CLFLAGS}"

# Log to the user
echo "ocamlrun:     ${OCAMLRUN}"
echo "ocaml:        ${OCAML}"
echo "ocamlc:       ${OCAMLC}"
echo "ocamlopt:     ${OCAMLOPT}"
echo "ocamllex:     ${OCAMLLEX}"
echo "ocamldep:     ${OCAMLDEP}"
echo "ocamlyacc:    ${OCAMLYACC}"
echo "ocamldoc_run: ${OCAMLDOC_RUN}"
echo "uninstalled libdir: ${LIBDIR}"

# Check the tool-specific dependencies
case "${TOOL}" in
  'debugger')
    echo 'Checking for sockets...'
    test_in_toplevel \
      'open Unix;;\nlet sock = socket PF_INET SOCK_STREAM 0;;' \
      'unix.cma'
    ;;
  'ocamldoc')
    ;;
  'ocamlbuild')
    ;;
  *)
    printf '\nERROR: you need to select a tool: "debugger", "ocamlbuild" or "ocamldoc".\n\n'
    exit 1
    ;;
esac

# Write the configuration summary to Makefile.local_config
cat > "${TOOL}/Makefile.local" << EOF
OCAML_MAKEFILE_CONFIG=${OCAML_MAKEFILE_CONFIG}
include \$(OCAML_MAKEFILE_CONFIG)
OCAML=${OCAML}
OCAMLC=${OCAMLC}
OCAMLOPT=${OCAMLOPT}
OCAMLLEX=${OCAMLLEX}
OCAMLDEP=${OCAMLDEP}
OCAMLYACC=${OCAMLYACC}
OCAMLDOC_RUN=${OCAMLDOC_RUN}
export CAML_LD_LIBRARY_PATH=${CAML_LD_LIBRARY_PATH}
UNINSTALLED_LIBDIR="${LIBDIR}"
EOF

echo "Successfully configured for '${TOOL}'."