#! /bin/sh

# Copyright (c) 2011, 2012 Spawngrid, Inc
# Copyright (c) 2011 Evax Software <contact(at)evax(dot)org>
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
# THE SOFTWARE.

ERLANG_DOWNLOAD_URL=http://www.erlang.org/download

KERL_BASE_DIR="$HOME/.kerl"
KERL_CONFIG="$HOME/.kerlrc"
KERL_DOWNLOAD_DIR="$KERL_BASE_DIR/archives"
KERL_BUILD_DIR="$KERL_BASE_DIR/builds"
KERL_GIT_DIR="$KERL_BASE_DIR/gits"
if [ -n "$KERL_CONFIGURE_OPTIONS" ]; then
    _KCO="$KERL_CONFIGURE_OPTIONS"
fi
if [ -n "$KERL_CONFIGURE_APPLICATIONS" ]; then
    _KCA="$KERL_CONFIGURE_APPLICATIONS"
fi
if [ -n "$KERL_CONFIGURE_DISABLE_APPLICATIONS" ]; then
    _KCDA="$KERL_CONFIGURE_DISABLE_APPLICATIONS"
fi
if [ -n "$KERL_SASL_STARTUP" ]; then
    _KSS="$KERL_SASL_STARTUP"
fi
if [ -n "$KERL_DEPLOY_SSH_OPTIONS" ]; then
    _KDSSH="$KERL_DEPLOY_SSH_OPTIONS"
fi
if [ -n "$KERL_DEPLOY_RSYNC_OPTIONS" ]; then
    _KDRSYNC="$KERL_DEPLOY_RSYNC_OPTIONS"
fi
if [ -n "$KERL_INSTALL_MANPAGES" ]; then
    _KIM="$KERL_INSTALL_MANPAGES"
fi
KERL_CONFIGURE_OPTIONS=
KERL_CONFIGURE_APPLICATIONS=
KERL_CONFIGURE_DISABLE_APPLICATIONS=
KERL_SASL_STARTUP=
KERL_INSTALL_MANPAGES=

# ensure the base dir exsists
mkdir -p "$KERL_BASE_DIR"

# source the config file if available
if [ -f "$KERL_CONFIG" ]; then . "$KERL_CONFIG"; fi

if [ -n "$_KCO" ]; then
    KERL_CONFIGURE_OPTIONS="$_KCO"
fi
if [ -n "$_KCA" ]; then
    KERL_CONFIGURE_APPLICATIONS="$_KCA"
fi
if [ -n "$_KCDA" ]; then
    KERL_CONFIGURE_DISABLE_APPLICATIONS="$_KCDA"
fi
if [ -n "$_KSS" ]; then
    KERL_SASL_STARTUP="$_KSS"
fi
if [ -n "$_KDSSH" ]; then
    KERL_DEPLOY_SSH_OPTIONS="$_KDSSH"
fi
if [ -n "$_KDRSYNC" ]; then
    KERL_DEPLOY_RSYNC_OPTIONS="$_KDRSYNC"
fi
if [ -n "$_KIM" ]; then
    KERL_INSTALL_MANPAGES="$_KIM"
fi

if [ -z "$KERL_SASL_STARTUP" ]; then
    INSTALL_OPT=-minimal
else
    INSTALL_OPT=-sasl
fi

KERL_SYSTEM=`uname -s`
case "$KERL_SYSTEM" in
    Darwin|FreeBSD|OpenBSD)
        MD5SUM="openssl md5"
        MD5SUM_FIELD=2
        SED_OPT=-E
        ;;
    *)
        MD5SUM=md5sum
        MD5SUM_FIELD=1
        SED_OPT=-r
        ;;
esac

usage()
{
    echo "kerl: build and install Erlang/OTP"
    echo "usage: $0 <command> [options ...]"
    echo "\n  <command>       Command to be executed\n"
    echo "Valid commands are:"
    echo "  build    Build specified release or git repository"
    echo "  install  Install the specified release at the given location"
    echo "  deploy   Deploy the specified installation to the given host and location"
    echo "  update   Update the list of available releases from erlang.org"
    echo "  list     List releases, builds and installations"
    echo "  delete   Delete builds and installations"
    echo "  active   Print the path of the active installation"
    echo "  status   Print available builds and installations"
    echo "  prompt   Print a string suitable for insertion in prompt"
    echo "  cleanup  Remove compilation artifacts (use after installation)"
    exit 1
}

if [ $# -eq 0 ]; then usage; fi

get_releases()
{
    curl -L -s $ERLANG_DOWNLOAD_URL/ | \
        sed $SED_OPT -e 's/^.*<[aA] [hH][rR][eE][fF]=\"\otp_src_([-0-9A-Za-z_.]+)\.tar\.gz\">.*$/\1/' \
                     -e '/^R1|^[0-9]/!d' | \
        sed -e "s/^R\(.*\)/\1:R\1/" | sed -e "s/^\([^\:]*\)$/\1-z:\1/" | sort | cut -d':' -f2
}

update_checksum_file()
{
    echo "Getting the checksum file from erlang.org..."
    curl -L $ERLANG_DOWNLOAD_URL/MD5 > "$KERL_DOWNLOAD_DIR/MD5" || exit 1
}

ensure_checksum_file()
{
    if [ ! -f "$KERL_DOWNLOAD_DIR/MD5" ]; then
        update_checksum_file
    fi
}

check_releases()
{
    if [ ! -f "$KERL_BASE_DIR/otp_releases" ]; then
        echo "Getting the available releases from erlang.org..."
        get_releases > "$KERL_BASE_DIR/otp_releases"
    fi
}

KERL_NO_LION_SUPPORT="R10B-0 R10B-2 R10B-3 R10B-4 R10B-5 R10B-6 R10B-7
R10B-8 R10B-9 R11B-0 R11B-1 R11B-2 R11B-3 R11B-4 R11B-5 R12B-0 R12B-1
R12B-2 R12B-3 R12B-4 R12B-5 R13A R13B R13B01 R13B02 R13B03 R13B04 R14A R14B R14B01 R14B02 R14B03"

lion_support() {
    for v in $KERL_NO_LION_SUPPORT; do
        if [ "$v" = "$1" ]; then
           return 1
        fi
    done
    return 0
}

is_valid_release()
{
    check_releases
    for rel in `cat $KERL_BASE_DIR/otp_releases`; do
        if [ "$1" = "$rel" ]; then
            return 0
        fi
    done
    return 1
}

assert_valid_release()
{
    if ! is_valid_release $1; then
        echo "$1 is not a valid Erlang/OTP release"
        exit 1
    fi
    return 0
}

get_release_from_name()
{
    if [ -f "$KERL_BASE_DIR/otp_builds" ]; then
        for l in `cat "$KERL_BASE_DIR/otp_builds"`; do
            rel=`echo $l | cut -d "," -f 1`
            name=`echo $l | cut -d "," -f 2`
            if [ "$name" = "$1" ]; then
                echo "$rel"
                return 0
            fi
        done
    fi
    return 1
}

get_newest_valid_release()
{
    check_releases
    for rel in `cat $KERL_BASE_DIR/otp_releases | tail -1`; do
        if [ ! -z "$rel" ]; then
            echo "$rel"
            return 0
        fi
    done
    return 1
}

is_valid_installation()
{
    if [ -f "$1/activate" ]; then
        return 0
    fi
    return 1
}

assert_valid_installation()
{
    if ! is_valid_installation $1; then
        echo "$1 is not a kerl-managed Erlang/OTP installation"
        exit 1
    fi
    return 0
}

assert_build_name_unused()
{
    if [ -f "$KERL_BASE_DIR/otp_builds" ]; then
        for l in `cat "$KERL_BASE_DIR/otp_builds"`; do
            name=`echo $l | cut -d "," -f 2`
            if [ "$name" = "$1" ]; then
                echo "There's already a build named $1"
                exit 1
            fi
        done
    fi
}

do_git_build()
{
    assert_build_name_unused $3

    GIT=`echo -n "$1" | $MD5SUM | cut -d " " -f $MD5SUM_FIELD`
    mkdir -p "$KERL_GIT_DIR"
    cd "$KERL_GIT_DIR"
    echo "Checking Erlang/OTP git repository from $1..."
    if [ ! -d "$GIT" ]; then
        git clone -q --mirror "$1" "$GIT" > /dev/null 2>&1
        if [ $? -ne 0 ]; then
            echo "Error mirroring remote git repository"
            exit 1
        fi
    fi
    cd "$GIT"
    git remote update --prune > /dev/null 2>&1
    if [ $? -ne 0 ]; then
        echo "Error updating remote git repository"
        exit 1
    fi

    rm -Rf "$KERL_BUILD_DIR/$3"
    mkdir -p "$KERL_BUILD_DIR/$3"
    cd "$KERL_BUILD_DIR/$3"
    git clone -l "$KERL_GIT_DIR/$GIT" otp_src_git > /dev/null 2>&1
    if [ $? -ne 0 ]; then
        echo "Error cloning local git repository"
        exit 1
    fi
    cd otp_src_git
    git checkout $2 > /dev/null 2>&1
    if [ $? -ne 0 ]; then
        git checkout -b $2 $2 > /dev/null 2>&1
    fi
    if [ $? -ne 0 ]; then
        echo "Couldn't checkout specified version"
        rm -Rf "$KERL_BUILD_DIR/$3"
        exit 1
    fi
    if [ ! -x otp_build ]; then
        echo "Not a valid Erlang/OTP repository"
        rm -Rf "$KERL_BUILD_DIR/$3"
        exit 1
    fi
    LOGFILE="$KERL_BUILD_DIR/$3/otp_build.log"
    echo "Building Erlang/OTP $3 from git, please wait..."
    ./otp_build autoconf $KERL_CONFIGURE_OPTIONS > "$LOGFILE" 2>&1 && \
        ./otp_build configure $KERL_CONFIGURE_OPTIONS > "$LOGFILE" 2>&1
    if [ $? -ne 0 ]; then
        echo "Build error, see $LOGFILE"
        exit 1
    fi
    if [ -n "$KERL_CONFIGURE_APPLICATIONS" ]; then
        find ./lib -maxdepth 1 -type d -exec touch -f {}/SKIP \;
        for i in $KERL_CONFIGURE_APPLICATIONS; do
            rm ./lib/$i/SKIP
            if [ $? -ne 0 ]; then
                echo "Couldn't prepare '$i' application for building"
                exit 1
            fi
        done
    fi
    if [ -n "$KERL_CONFIGURE_DISABLE_APPLICATIONS" ]; then
        for i in $KERL_CONFIGURE_DISABLE_APPLICATIONS; do
            touch -f ./lib/$i/SKIP
            if [ $? -ne 0 ]; then
                echo "Couldn't disable '$i' application for building"
                exit 1
            fi
        done
    fi
    ./otp_build boot -a $KERL_CONFIGURE_OPTIONS > "$LOGFILE" 2>&1
    if [ $? -ne 0 ]; then
        echo "Build error, see $LOGFILE"
        exit 1
    fi
    rm -f "$LOGFILE"
    ./otp_build release -a "$KERL_BUILD_DIR/$3/release_git" > /dev/null 2>&1
    cd "$KERL_BUILD_DIR/$3/release_git"
    ./Install $INSTALL_OPT "$KERL_BUILD_DIR/$3/release_git" > /dev/null 2>&1
    echo "Erlang/OTP $3 from git has been successfully built"
    list_add builds "git,$3"
}

do_build()
{
    case "$KERL_SYSTEM" in
        Darwin)
            if [ `gcc --version 2>/dev/null | grep -i llvm | wc -l` = "1" ]; then
                if lion_support $1; then
                    KERL_CONFIGURE_OPTIONS="CFLAGS=-O0 $KERL_CONFIGURE_OPTIONS"
                else
                    if [ -x "`which gcc-4.2`" ]; then
                        KERL_CONFIGURE_OPTIONS="CC=gcc-4.2 $KERL_CONFIGURE_OPTIONS"
                    else
                        KERL_CONFIGURE_OPTIONS="CC=llvm-gcc-4.2 CFLAGS=-O0 $KERL_CONFIGURE_OPTIONS"
                    fi
                fi
            fi
        ;;
        *)
        ;;
    esac

    assert_valid_release $1
    assert_build_name_unused $2

    FILENAME=otp_src_$1.tar.gz
    download "$FILENAME"
    mkdir -p "$KERL_BUILD_DIR/$2"
    if [ ! -d "$KERL_BUILD_DIR/$2/otp_src_$1" ]; then
        echo "Extracting source code"
        UNTARDIRNAME="$KERL_BUILD_DIR/$2/otp_src_$1-kerluntar-$$"
        rm -rf "$UNTARDIRNAME"
        mkdir -p "$UNTARDIRNAME"
        (cd "$UNTARDIRNAME" && tar xfz "$KERL_DOWNLOAD_DIR/$FILENAME" && mv * "$KERL_BUILD_DIR/$2/otp_src_$1")
        rm -rf "$UNTARDIRNAME"
    fi
    echo "Building Erlang/OTP $1 ($2), please wait..."
    ERL_TOP="$KERL_BUILD_DIR/$2/otp_src_$1"
    cd "$ERL_TOP"
    LOGFILE="$KERL_BUILD_DIR/$2/otp_build_$1.log"
    if [ -n "$KERL_USE_AUTOCONF" ]; then
        ./otp_build autoconf $KERL_CONFIGURE_OPTIONS > "$LOGFILE" 2>&1 && \
            ./otp_build configure $KERL_CONFIGURE_OPTIONS > "$LOGFILE" 2>&1
    else
        ./otp_build configure $KERL_CONFIGURE_OPTIONS > "$LOGFILE" 2>&1

    fi
    if [ $? -ne 0 ]; then
        echo "Build failed, see $LOGFILE"
        list_remove builds "$1 $2"
        exit 1
    fi
    if [ -n "$KERL_CONFIGURE_APPLICATIONS" ]; then
        find ./lib -maxdepth 1 -type d -exec touch -f {}/SKIP \;
        for i in $KERL_CONFIGURE_APPLICATIONS; do
            rm ./lib/$i/SKIP
            if [ $? -ne 0 ]; then
                echo "Couldn't prepare '$i' application for building"
                list_remove builds "$1 $2"
                exit 1
            fi
        done
    fi
    if [ -n "$KERL_CONFIGURE_DISABLE_APPLICATIONS" ]; then
        for i in $KERL_CONFIGURE_DISABLE_APPLICATIONS; do
            touch -f ./lib/$i/SKIP
            if [ $? -ne 0 ]; then
                echo "Couldn't disable '$i' application for building"
                exit 1
            fi
        done
    fi
    ./otp_build boot -a $KERL_CONFIGURE_OPTIONS > "$LOGFILE" 2>&1
    if [ $? -ne 0 ]; then
        echo "Build failed, see $LOGFILE"
        list_remove builds "$1 $2"
        exit 1
    fi
    rm -f "$LOGFILE"
    ERL_TOP="$ERL_TOP" ./otp_build release -a "$KERL_BUILD_DIR/$2/release_$1" > /dev/null 2>&1
    cd "$KERL_BUILD_DIR/$2/release_$1"
    ./Install $INSTALL_OPT "$KERL_BUILD_DIR/$2/release_$1" > /dev/null 2>&1
    echo "Erlang/OTP $1 ($2) has been successfully built"
    list_add builds "$1,$2"
}

do_install()
{
    rel=`get_release_from_name $1`
    if [ $? -ne 0 ]; then
        echo "No build named $1"
        exit 1
    fi
    mkdir -p "$2"
    if [ ! -d "$2" ]; then
        echo "Destination is not a directory"
        exit 1
    fi
    absdir=`cd "$2" && pwd`
    echo "Installing Erlang/OTP $rel ($1) in $absdir..."
    ERL_TOP="$KERL_BUILD_DIR/$1/otp_src_$rel"
    cd "$ERL_TOP"
    ERL_TOP="$ERL_TOP" ./otp_build release -a "$absdir" > /dev/null 2>&1 &&
        cd "$absdir" && ./Install $INSTALL_OPT "$absdir" > /dev/null 2>&1
    if [ $? -ne 0 ]; then
        echo "Couldn't install Erlang/OTP $rel ($1) in $absdir"
        exit 1
    fi
    list_add installations "$1 $absdir";
    cat <<ACTIVATE > "$absdir/activate"
# credits to virtualenv
kerl_deactivate()
{
    if [ -n "\$_KERL_PATH_REMOVABLE" ]; then
        PATH=\${PATH//\${_KERL_PATH_REMOVABLE}:/}
        export PATH
        unset _KERL_PATH_REMOVABLE
    fi
    if [ -n "\$_KERL_MANPATH_REMOVABLE" ]; then
        MANPATH=\${MANPATH//\${_KERL_MANPATH_REMOVABLE}:/}
        export MANPATH
        unset _KERL_MANPATH_REMOVABLE
    fi
    if [ -n "\$_KERL_SAVED_REBAR_PLT_DIR" ]; then
        REBAR_PLT_DIR="\$_KERL_SAVED_REBAR_PLT_DIR"
        export REBAR_PLT_DIR
        unset _KERL_SAVED_REBAR_PLT_DIR
    fi
    if [ -n "\$_KERL_ACTIVE_DIR" ]; then
        unset _KERL_ACTIVE_DIR
    fi
    if [ -n "\$_KERL_SAVED_PS1" ]; then
        PS1="\$_KERL_SAVED_PS1"
        export PS1
        unset _KERL_SAVED_PS1
    fi
    if [ -n "\$BASH" -o -n "\$ZSH_VERSION" ]; then
        hash -r
    fi
    if [ ! "\$1" = "nondestructive" ]; then
        unset -f kerl_deactivate
    fi
}
kerl_deactivate nondestructive

_KERL_SAVED_REBAR_PLT_DIR="\$REBAR_PLT_DIR"
export _KERL_SAVED_REBAR_PLT_DIR
_KERL_PATH_REMOVABLE="$absdir/bin"
PATH="\${_KERL_PATH_REMOVABLE}:\$PATH"
export PATH _KERL_PATH_REMOVABLE
_KERL_MANPATH_REMOVABLE="$absdir/man"
MANPATH="\${_KERL_MANPATH_REMOVABLE}:\$MANPATH"
export MANPATH _KERL_MANPATH_REMOVABLE
REBAR_PLT_DIR="$absdir"
export REBAR_PLT_DIR
_KERL_ACTIVE_DIR="$absdir"
export _KERL_ACTIVE_DIR
if [ -f "$KERL_CONFIG" ]; then . "$KERL_CONFIG"; fi
if [ -n "\$KERL_ENABLE_PROMPT" ]; then
    _KERL_SAVED_PS1="\$PS1"
    export _KERL_SAVED_PS1
    PS1="($1)\$PS1"
    export PS1
fi
if [ -n "\$BASH" -o -n "\$ZSH_VERSION" ]; then
    hash -r
fi
ACTIVATE
    if [ "$rel" != "git" ]; then
        if [ -n "$KERL_INSTALL_MANPAGES" ]; then
            echo "Fetching and installing manpages..."
            FILENAME=otp_doc_man_$rel.tar.gz
            download "$FILENAME"
            echo "Extracting manpages"
            cd "$absdir" && tar xfz "$KERL_DOWNLOAD_DIR/$FILENAME"
        fi

        if [ -n "$KERL_INSTALL_HTMLDOCS" ]; then
            echo "Fetching and installing HTML docs..."
            FILENAME="otp_doc_html_$rel.tar.gz"
            download "$FILENAME"
            echo "Extracting HTML docs"
            (cd "$absdir" && mkdir -p html && \
                tar -C "$absdir/html" -xzf "$KERL_DOWNLOAD_DIR/$FILENAME")
        fi
    else
        rel=`get_newest_valid_release`
        if [ $? -ne 0 ]; then
            echo "No newest valid release"
            exit 1
        fi

        if [ -n "$KERL_INSTALL_MANPAGES" ]; then
            echo "CAUTION: Fetching and installing newest ($rel) manpages..."
            FILENAME=otp_doc_man_$rel.tar.gz
            download "$FILENAME"
            echo "Extracting manpages"
            cd "$absdir" && tar xfz "$KERL_DOWNLOAD_DIR/$FILENAME"
        fi

        if [ -n "$KERL_INSTALL_HTMLDOCS" ]; then
            echo "CATION: Fetching and installing newest ($rel) HTML docs..."
            FILENAME="otp_doc_html_$rel.tar.gz"
            download "$FILENAME"
            echo "Extracting HTML docs"
            (cd "$absdir" && mkdir -p html && \
                tar -C "$absdir/html" -xzf "$KERL_DOWNLOAD_DIR/$FILENAME")
        fi
    fi

    echo "You can activate this installation running the following command:"
    echo ". $absdir/activate"
    echo "Later on, you can leave the installation typing:"
    echo "kerl_deactivate"
}

do_deploy()
{
    if [ -z "$1" ]; then
        echo "No host given"
        exit 1
    fi
    host=$1

    assert_valid_installation "$2"
    rel=`get_name_from_install_path "$2"`
    path=$2
    remotepath=$path

    if [ ! -z "$3" ]; then
        remotepath=$3
    fi

    ssh $KERL_DEPLOY_SSH_OPTIONS $host true > /dev/null 2>&1
    if [ $? -ne 0 ]; then
        echo "Couldn't ssh to $host"
        exit 1
    fi

    echo "Cloning Erlang/OTP $rel ($path) to $host ($remotepath) ..."

    rsync -aqz -e "ssh $KERL_DEPLOY_SSH_OPTIONS" $KERL_DEPLOY_RSYNC_OPTIONS "$path/" "$host:$remotepath/"
    if [ $? -ne 0 ]; then
        echo "Couldn't rsync Erlang/OTP $rel ($path) to $host ($remotepath)"
        exit 1
    fi

    ssh $KERL_DEPLOY_SSH_OPTIONS $host "cd \"$remotepath\" && env ERL_TOP=\`pwd\` ./Install $INSTALL_OPT \`pwd\` > /dev/null 2>&1"
    if [ $? -ne 0 ]; then
        echo "Couldn't install Erlang/OTP $rel to $host ($remotepath)"
        exit 1
    fi

    ssh $KERL_DEPLOY_SSH_OPTIONS $host "cd \"$remotepath\" && sed -i -e \"s#$path#\`pwd\`#g\" activate"
    if [ $? -ne 0 ]; then
        echo "Couldn't completely install Erlang/OTP $rel to $host ($remotepath)"
        exit 1
    fi

    echo "On $host, you can activate this installation running the following command:"
    echo ". $remotepath/activate"
    echo "Later on, you can leave the installation typing:"
    echo "kerl_deactivate"
}

list_print()
{
    if [ -f $KERL_BASE_DIR/otp_$1 ]; then
        if [ "`cat "$KERL_BASE_DIR/otp_$1" | wc -l`" != "0" ]; then
            if [ -z "$2" ]; then
                cat "$KERL_BASE_DIR/otp_$1"
            else
                echo `cat "$KERL_BASE_DIR/otp_$1"`
            fi
            return 0
        fi
    fi
    echo "There are no $1 available"
}

list_add()
{
    if [ -f "$KERL_BASE_DIR/otp_$1" ]; then
        for l in `cat "$KERL_BASE_DIR/otp_$1"`; do
            if [ "$l" = "$2" ]; then
                return 1
            fi
        done
        echo "$2" >> "$KERL_BASE_DIR/otp_$1"
    else
        echo "$2" > "$KERL_BASE_DIR/otp_$1"
    fi
}

list_remove()
{
    if [ -f "$KERL_BASE_DIR/otp_$1" ]; then
        sed $SED_OPT -i -e "/^.*$2$/d" "$KERL_BASE_DIR/otp_$1"
    fi
}

list_has()
{
    if [ -f "$KERL_BASE_DIR/otp_$1" ]; then
        grep $2 "$KERL_BASE_DIR/otp_$1" > /dev/null 2>&1 && return 0
    fi
    return 1
}

list_usage()
{
    echo "usage: $0 list <releases|builds|installations>"
}

delete_usage()
{
    echo "usage: $0 delete <build|installation> <build_name or path>"
}

cleanup_usage()
{
    echo "usage: $0 cleanup <build_name|all>"
}

update_usage()
{
    echo "usage: $0 update releases"
}

get_active_path()
{
    if [ -n "$_KERL_ACTIVE_DIR" ]; then
        echo $_KERL_ACTIVE_DIR
    fi
    return 0
}

get_name_from_install_path()
{
    if [ -f "$KERL_BASE_DIR/otp_installations" ]; then
        grep -F "$1" "$KERL_BASE_DIR/otp_installations" | cut -d ' ' -f 1
    fi
    return 0
}

do_active()
{
    ACTIVE_PATH=`get_active_path`
    if [ -n "$ACTIVE_PATH" ]; then
        echo "The current active installation is:"
        echo $ACTIVE_PATH
        return 0
    else
        echo "No Erlang/OTP kerl installation is currently active"
        return 1
    fi
}

download()
{
    if [ ! -f "$KERL_DOWNLOAD_DIR/$1" ]; then
        echo "Downloading $1 to $KERL_DOWNLOAD_DIR"
        mkdir -p "$KERL_DOWNLOAD_DIR"
        curl -L "$ERLANG_DOWNLOAD_URL/$1" > "$KERL_DOWNLOAD_DIR/$1"
        update_checksum_file
    fi
    ensure_checksum_file
    echo "Verifying archive checksum..."
    SUM=`$MD5SUM "$KERL_DOWNLOAD_DIR/$1" | cut -d " " -f $MD5SUM_FIELD`
    ORIG_SUM=`grep -F "$1" "$KERL_DOWNLOAD_DIR/MD5" | cut -d " " -f 2`
    if [ "$SUM" != "$ORIG_SUM" ]; then
        echo "Checksum error, check the files in $KERL_DOWNLOAD_DIR"
        exit 1
    fi
    echo "Checksum verified ($SUM)"
}

case "$1" in
    build)
        if [ "$2" = "git" ]; then
            if [ $# -ne 5 ]; then
                echo "usage: $0 $1 $2 <git_url> <git_version> <build_name>"
                exit 1
            fi
            do_git_build $3 $4 $5
        else
            if [ $# -lt 3 ]; then
                echo "usage: $0 $1 <release> <build_name>"
                exit 1
            fi
            do_build $2 $3
        fi
        ;;
    install)
        if [ $# -lt 2 ]; then
            echo "usage: $0 $1 <build_name> [directory]"
            exit 1
        fi
        if [ $# -eq 3 ]; then
            if [ "$3" = "$HOME" ]; then
                echo "Refusing to install in $HOME, this is a bad idea."
                exit 1
            else
                do_install $2 "$3"
            fi
        else
            if [ -z "$KERL_DEFAULT_INSTALL_DIR" ]; then
                if [ "$PWD" = "$HOME" ]; then
                    echo "Refusing to install in $HOME, this is a bad idea."
                    exit 1
                else
                    do_install $2 .
                fi
            else
                do_install $2 "$KERL_DEFAULT_INSTALL_DIR/$2"
            fi
        fi
        ;;
    deploy)
        if [ $# -lt 2 ]; then
            echo "usage: $0 $1 <[user@]host> [directory] [remote_directory]"
            exit 1
        fi
        if [ $# -eq 4 ]; then
            do_deploy $2 "$3" "$4"
        else
            if [ $# -eq 3 ]; then
                do_deploy $2 "$3"
            else
                do_deploy $2 .
            fi
        fi
        ;;
    update)
        if [ $# -lt 2 ]; then
            update_usage
            exit 1
        fi
        case "$2" in
            releases)
                rm -f "$KERL_BASE_DIR/otp_releases"
                check_releases
                echo "The available releases are:"
                list_print releases spaces
                ;;
            *)
                update_usage
                exit 1
                ;;
        esac
        ;;
    list)
        if [ $# -ne 2 ]; then
            list_usage
            exit 1
        fi
        case "$2" in
            releases)
                check_releases
                list_print $2 space
                echo "Run \"$0 update releases\" to update this list from erlang.org"
                ;;
            builds)
                list_print $2
                ;;
            installations)
                list_print $2
                ;;
            *)
                echo "Cannot list $2"
                list_usage
                exit 1
                ;;
        esac
        ;;
    delete)
        if [ $# -ne 3 ]; then
            delete_usage
            exit 1
        fi
        case "$2" in
            build)
                rel=`get_release_from_name $3`
                if [ -d "$KERL_BUILD_DIR/$3" ]; then
                    rm -Rf "$KERL_BUILD_DIR/$3"
                else
                    if [ -z "$rel" ]; then
                      echo "No build named $3"
                      exit 1
                    fi
                fi
                list_remove $2s "$rel,$3"
                echo "The $3 build has been deleted"
                ;;
            installation)
                assert_valid_installation "$3"
                rm -Rf "$3"
                escaped=`echo "$3" | sed $SED_OPT -e 's#/$##' -e 's#\/#\\\/#g'`
                list_remove $2s "$escaped"
                echo "The installation in $3 has been deleted"
                ;;
            *)
                echo "Cannot delete $2"
                delete_usage
                exit 1
                ;;
        esac
        ;;
    active)
        if ! do_active; then
            exit 1;
        fi
        ;;
    status)
        echo "Available builds:"
        list_print builds
        echo "----------"
        echo "Available installations:"
        list_print installations
        echo "----------"
        do_active
        exit 0
        ;;
    prompt)
        FMT=" (%s)"
        if [ -n "$2" ]; then
            FMT="$2"
        fi
        ACTIVE_PATH=`get_active_path`
        if [ -n "$ACTIVE_PATH" ]; then
            ACTIVE_NAME=`get_name_from_install_path "$ACTIVE_PATH"`
            if [ -z "$ACTIVE_NAME" ]; then
                VALUE="`basename "$ACTIVE_PATH"`*"
            else
                VALUE="$ACTIVE_NAME"
            fi
            printf "$FMT" "$VALUE"
        fi
        exit 0
        ;;
    cleanup)
        if [ $# -ne 2 ]; then
            cleanup_usage
            exit 1
        fi
        case "$2" in
            all)
                echo "Cleaning up compilation products for ALL builds"
                rm -rf $KERL_BUILD_DIR/*
                rm -rf $KERL_DOWNLOAD_DIR/*
                rm -rf $KERL_GIT_DIR/*
                echo "Cleaned up all compilation products under $KERL_BUILD_DIR"
                ;;
            *)
                echo "Cleaning up compilation products for $3"
                rm -rf $KERL_BUILD_DIR/$3
                echo "Cleaned up all compilation products under $KERL_BUILD_DIR"
                ;;
        esac
        ;;
    *)
        echo "unknown command: $1"; usage; exit 1
        ;;
esac