#!/usr/bin/env bash
## repository at https://github.com/ryanmjacobs/c
VERSION=v0.15-dev

# max cachesize in kilobytes (default=5MB)
[[ -z "$C_CACHE_SIZE" ]] && C_CACHE_SIZE=$((5*1024))
if ! [[ "$C_CACHE_SIZE" =~ ^[0-9]*$ ]]; then
    C_CACHE_SIZE=$((5*1024))
    >&2 echo 'warning: $C_CACHE_SIZE should be a positive integer'
fi

help_msg() {
    >&$1 echo "Usage: $(basename "$0") <file.c ... | compiler_options ...> [program_arguments]"
    >&$1 echo "       $(basename "$0") --clear-cache"
    >&$1 echo 'Execute C programs from the command line.'
    >&$1 echo
    >&$1 echo '  Ex: c main.c'
    >&$1 echo '  Ex: c main.c arg1 arg2'
    >&$1 echo "  Ex: c 'main.c other.c' arg1 arg2"
    >&$1 echo "  Ex: c 'main.c -lncurses' arg1 arg2"
    >&$1 echo
}

cleanup() {
    # remove temporary source directory
    rm -rf "$tmpdir"

    # remove cache files until we are under $cachesize
    if [ "$(uname -s)" == "SunOS" ] ; then ducmd="du -ks" ; else ducmd="du -kc" ; fi
    while [[ "$($ducmd "$tmproot" | tail -1 | cut -f1)" -gt "$C_CACHE_SIZE" ]]; do
        [[ -z "$(ls -A "$tmproot")" ]] && break
        rm -rf "$(find "$tmproot" | tail -n1)"
    done
}

# Handle --help, -h, and zero args
[[ "$1" == "--help" || "$1" == "-h" ]] && { help_msg 1; exit 0; }
[[ "$#" -lt 1 ]] && { help_msg 2; exit 2; }

# get cache location
if [[ -n "$C_CACHE_PATH" ]]; then
    tmproot="$C_CACHE_PATH"
else
    [[ -z "$TMPDIR" ]] && TMPDIR="/tmp"
    tmproot="$TMPDIR/c.cache.$USER"
fi

# Hadle --clear-cache
[[ "$1" == "--clear-cache" ]] && exec rm -rf "$tmproot"

# ensure our $CC and $CXX variables are set
[[ -z "$CC" ]]  && CC=cc
[[ -z "$FC" ]]  && FC=gfortran
[[ -z "$CXX" ]] && CXX=c++
if ! hash "$CC" &>/dev/null; then
    >&2 echo "error: \$CC ($CC) not found"
    exit 1
fi

# $comp holds the files and options that will be passed to the compiler
# $fname will become the program's argv[0]
if [ -f "$1" ]; then
    # given only one file, so that must be our source file
    comp=("$1")
    fname="$1"
else
    # capture all of our source files,
    # use the first file as our fname
    for arg in $1; do
        if [[ "$arg" == "--" ]]; then
            fname="$2"
            comp=("$2" "${comp[@]}")
            shift
        else
            comp+=("$arg")
        fi
    done

    # if we don't have an fname yet, pick one out of $comp
    # that doesn't start with a '-'
    if [[ -z "$fname" ]]; then
        for arg in $1; do
            if [[ "$arg" != -* ]]; then
                fname="$arg"
                break
            fi
        done
    fi
fi

# create cache location
mkdir -p "$tmproot"
chmod 700 "$tmproot"

# decide on a hash function by using the first one we find
potential_hashes=(md5sum sha256sum sha1sum shasum)
hash_func=:
for hf in "${potential_hashes[@]}"; do
    hash "$hf" &>/dev/null && { hash_func="$hf"; break; }
done

# disable caching if we don't locate a hashing function
[ "$hash_func" == : ] && C_CACHE_SIZE=0

# determine if we are C, C++ or Fortran, then use appropriate flags
is_cpp=false
is_fortran=false
for f in "$fname" "${comp[@]}"; do
    # only examine files
    [[ ! -f "$f" ]] && continue

    # if one file has a C++ extension, then the whole set is C++
    if [[ "$f" =~ \.(cc|c\+\+|cpp|cxx)$ ]]; then
        is_cpp=true

        if hash "$CXX" &>/dev/null; then
            # found $CXX, we will use that
            CC="$CXX"
            comp+=("$CXXFLAGS")
        else
            # couldn't find $CXX, so we make do with $CC and -lstdc++
            comp+=("$CFLAGS -lstdc++")
        fi

        break
    fi

    # if one file has a Fortran extension, then the whole set is Fortran
    # We have to check case insensitive because many fortran suffixes are
    # uppercase
    shopt -s nocasematch
    if [[ "$f" =~ \.(f|f95|f77|f90|f03|f15|for)$ ]]; then
      is_fortran=true
      CC="${FC}"
      comp+=(${FCFLAGS})
    fi
    shopt -u nocasematch

done

# add $CFLAGS if and only if we are not C++
if [[ "$is_cpp" == false && "${is_fortran}" == false ]]; then
    comp+=($CFLAGS)
fi

# add preprocessor flags
comp+=("$CPPFLAGS")

# hash all of our data
prehash="$CC ${comp[*]}" # compiler + flags and files
for f in "${comp[@]}"; do
    [ -f "$f" ] && prehash+="$f $(cpp "$f" 2>&1)"
done

# hash everything into one unique identifier, for caching purposes
id="c$("$hash_func" <<< "$prehash" | cut -d' ' -f1)"
tmpdir="$tmproot/$id.src"
binname="$tmproot/$id.bin"

# run binary
run() {
    trap cleanup SIGINT

    if [ -x "$binname" ]; then
      shift
      (exec -a "$fname" "$binname" "$@")
      ret=$?
    else
      echo
      ret=4
    fi

    trap - SIGINT
    cleanup
    exit $ret
}

# run cached file if it exists
if [[ -f "$binname" ]]; then
    run "$@"
else
    mkdir -p "$tmpdir"
fi

# assemble our includes, based on the original file locations
includes=("-I'$PWD'")
for f in "${comp[@]}"; do
    [[ -f "$f" ]] && includes+=("-I'$(dirname "$f")'")
done

i=0
# copy source files to $tmpdir
for f in "${comp[@]}"; do
    if [[ -f "$f" && "$f" != $tmpdir* ]]; then
        mkdir -p "$tmpdir/$(dirname "$f")"
        cp "$f" "$tmpdir/$f"

        # assume language is C, if no extension is given
        base="$(basename "$f")"
        ext="${base##*.}"
        if [[ "$ext" == "$base" ]]; then
            comp[$i]="-x c $tmpdir/$f -x none"
        else
            comp[$i]="$tmpdir/$f"
        fi

        # remove shebangs from every source file
        if [[ "$(head -n1 "$tmpdir/$f")" == \#\!* ]]; then
            echo "$(tail -n +2 "$tmpdir/$f")" > "$tmpdir/$f"
        fi
    fi
    let i++
done

# final operations before compilation
rest=()
flags=()
for f in "${comp[@]}"; do
    # skip empty elements
    [[ -z "$f" ]] && break

    # separate the flags from other arguments
    [[ "$f" =~ ^- ]] &&\
        flags+=("$f") ||\
        rest+=("$f")
done

# compile and run

# kludgey fix for gcc arguments
out="$("$CC" -O2 -o "$binname" ${flags[@]} "${includes[@]}" "${rest[@]}" 2>&1)"
if [ $? -ne 0 ]; then
    eval "$CC" -O2 -o "$binname" ${flags[@]} "${includes[@]}" "${rest[@]}"
else
    echo -n "$out"
fi

if [ $? -eq 0 ]; then
    run "$@"
else
    cleanup
    exit 1
fi