install

#!/usr/bin/env bash

# install and uninstall script for dyetide bash script and data files

# Requires root privilege unless --user / --home is used
# Use --dry-run first to preview what will be done

usage() {
cat << EOM
$0 [options]
Options:
 --user, --home             install to (uninstall from) home directory
 --dry-run                  prints actions rather than performing them
 -v, --verbose              print verbose information
 -h, --help                 output usage information

Environment variables that affect installation:
 PREFIX                     default: /usr/local **
 BINDIR                     default: PREFIX/bin
 DATADIR                    default: PREFIX/share
 MANDIR                     default: DATADIR/man

** If --user/--home specified, PREFIX defaults to ~/.local
EOM
}

do_log() {
    printf "%s\n" "$*" 1>&2
    return 0
}

# Determine elevation mechanism
if command -v "doas" &> /dev/null ; then
    __elev="doas"
else
    __elev="sudo"
fi

# Parse arguments
for arg in "$@" ; do
    case "$arg" in
        --user|--home)
            PREFIX="${PREFIX:-${HOME}/.local}"
            __elev=""
            ;;
        --verbose|-v)
            __verbose=1
            ;;
        --dry-run)
            __log=do_log
            ;;
        --help|-h)
            usage
            exit 0
            ;;
    esac
done

bindir="${BINDIR:-${PREFIX:-/usr/local}/bin}"
datadir="${DATADIR:-${PREFIX:-/usr/local}/share}"
mandir="${MANDIR:-$datadir/man}"

if [[ -n $__verbose ]] ; then
    echo "BINDIR=\"$bindir\""
    echo "DATADIR=\"$datadir\""
    echo "MANDIR=\"$mandir\""
    [[ -n $__elev ]] && echo "using $__elev for privilege elevation"
fi

error() {
    printf "error: %s\n" "$1" 1>&2
    ${2:+exit $2}
}

dependencycheck() {
    local dep missingdependencies=0
    for dep in "$@" ; do
        if ! command -v "$dep" &> /dev/null ; then
            error "dependency not met: $dep"
        fi
    done
    if [[ $missingdependencies -gt 0 ]] ; then
        exit 1
    fi
}


function changeowner() {
        [[ -n $__elev ]] || return
        $__log $__elev chown -R "$USER":"$USER" ./*
}

function overwrite() {
    local resp
    read -e -r -p "$1(y/n): " resp
    case "$resp" in
        [Yy]|yes)
            return 0
            ;;
        *)
            printf "%s\n" "no change made"
            ;;
    esac
    return 1
}

function install_binfile() {
    local file base
    for file in "$@"; do
        base="${file##*/}"
        if [[ -f "$bindir/$base" ]] ; then
            overwrite "$base already installed, would you like to reinstall?" || continue
        fi
        $__log $__elev cp "$file" "$bindir/" || error "failed to create $bindir/$base"
        $__log $__elev chmod 755 "$bindir/$base" || error "failed to change permission of $bindir/$base"
    done
}

function uninstall_binfile() {
    local file
    for file in "$@"; do
        [[ -e "$bindir/$file" ]] || continue
        $__log $__elev rm -f "$bindir/$file" || error "failed to remove $bindir/$file"
    done
}

function install_data() {
    if [[ -d "$datadir/dyetide" ]] ; then
        overwrite "$datadir/dyetide directory already exists, would you like to overwrite configuration files?" || return
        $__log $__elev rm -rf "$datadir/dyetide" || error "failed to remove existing $datadir/dyetide directory" 2
    fi
    printf "%s\n" "installing configuration files in directory $datadir/dyetide/ ..."
    $__log $__elev mkdir -p "$datadir/dyetide" || error "failed to create $datadir/dyetide directory" 2
    local target
    for target in "$@" ; do
        $__log $__elev cp -r "$target" "$datadir/dyetide/" || error "failed to copy $target to $datadir/dyetide"
    done
}

function uninstall_data() {
    [[ -d "$datadir/dyetide" ]] || return
    $__log $__elev rm -rf "$datadir/dyetide" || error "failed to remove $datadir/dyetide directory"
}

function install_manfile() {
    local sub file base
    sub="$1"; shift
    $__log $__elev mkdir -p "$mandir/$sub" || error "failed to create $mandir/$sub directory" 2
    for file in "$@" ; do
        base="${file##*/}"
        if [[ -f "$mandir/$sub/$base" ]] ; then
            overwrite "$base already installed, would you like to reinstall?" || continue
        fi
        $__log $__elev cp "$file" "$mandir/$sub" || error "failed to create $mandir/$sub/$base"
    done
}

function uninstall_manfile() {
    local sub file
    sub="$1"; shift
    for file in "$@"; do
        [[ -e "$mandir/$sub/$file" ]] || continue
        $__log $__elev rm -f "$mandir/$sub/$file" || error "failed to remove $mandir/$sub/$file"
    done
}

#
# main routine
#

case "$0" in
    *uninstall*)
        dependencycheck $__elev rm
        uninstall_binfile dyetide dye
        uninstall_manfile man1 dyetide.1.gz
        ;;
    *)
        changeowner
        dependencycheck $__elev chown cp chmod mkdir date awk sed rm find sort grep
        install_binfile dyetide dye
        install_manfile man1 man_page/*.1.gz
        ;;
esac