#!/usr/bin/env bash

# README:
#
#   The `ffi` module has a sub module for each supported O/S (curently only Mac)
#   and each of these contains the same four bindings; `langinfo`, `localcharset`,
#   `locale`, and `xlocale`. In this way the interface to the library above
#   is always the same and bindings have not yet needed to be edited in any
#   way.

case $(uname) in
  Darwin)
    if [[ $(command -v llvm-config) ]] ; then
	MAC_PLATFORM=MacOSX
	INCLUDE="$(xcode-select -p)/Platforms/$MAC_PLATFORM.platform/Developer/SDKs/$MAC_PLATFORM.sdk/usr/include"
	BIND_HEADERS=langinfo,locale,xlocale
	MODULE=macos
    else
        echo "llvm not installed, or not on the path, try:"
        echo "$ brew install llvm"
        echo "$ PATH=\$PATH:/usr/local/opt/llvm/bin"
        exit 2
    fi
    ;;
  Linux)
    if [[ $(command -v llvm-config) ]] ; then
	INCLUDE="/usr/include"
	BIND_HEADERS=langinfo,locale
	MODULE=linux
    else
        echo "llvm not installed, or not on the path, try:"
	echo "sudo apt-get install llvm"
	echo "sudo apt-get install clang"
	exit 2
    fi
    ;;
  *)
    echo "Unsupported O/S"
    exit 1
    ;;
esac

mkdir -p src/ffi/$MODULE

if [[ ! $(command -v bindgen) ]] ; then
    cargo install bindgen
    cargo install rustfmt
fi

MODULES=""
for HEADER in ${BIND_HEADERS//,/ }
do
  if [[ -f "$INCLUDE/$HEADER.h" ]] ; then
    echo "generating bindings for $INCLUDE/$HEADER.h into src/ffi/$MODULE/$HEADER.rs"
    bindgen --verbose $INCLUDE/$HEADER.h --output src/ffi/$MODULE/$HEADER.rs
    git add src/ffi/$MODULE/$HEADER.rs
    MODULES=$(printf "%s\n#[allow(non_snake_case, non_camel_case_types, dead_code, unused_variables)]\npub mod %s;\n" "$MODULES" $HEADER)
  else
    echo "header file $HEADER.h does not exist in $INCLUDE"
  fi
done

VERSION_FILE="src/ffi/$MODULE/mod.rs"

echo "writing module file in $VERSION_FILE"

cat <<EOF > "$VERSION_FILE"
/* automatically generated by create-bindings */
/* generated on $(date), */
/*   for $(uname -s), release $(uname -r) */
$MODULES
EOF
git add $VERSION_FILE