#!/usr/bin/env bash

if [ -z "$(which realpath)" ]; then
    realpath() {
        rpath=$1
        if [ "${rpath[0]}" == "/" ]; then
            echo $rpath;
        elif [ "${rpath:0:1}" == "~" ]; then
            echo $HOME/${rpath:2}
        elif [ "${rpath:0:2}" == ".." ]; then
            echo $(dirname $(pwd))/${rpath:3}
        elif [ "${rpath:0:1}" == "." ]; then
            echo $(pwd)/${rpath:2}
        else
            echo $(pwd)/$rpath
        fi
    }
fi


stow() {
    local stowrepo=$1
    local stowtarget=$2
   
    [ "$VERBOSE" -gt 1 ] && echo "Entering $stowrepo..."

    local files=()
    while read line; do
        if [ "$line" != "." -a "$line" != ".." ]; then
            files+=("$line")
        fi
    done < <(ls -a $stowrepo)
    
    [ "$VERBOSE" -gt 1 ] && echo "Filelist: ${files[@]}"

    for file in "${files[@]}"; do
        local file=$(basename "$file")
        local ctarget="$stowtarget/$file"
        local csource="$stowrepo/$file"
        if [ -e "$ctarget" ]; then
            if [ -L "$ctarget" -a "$(readlink -f "$ctarget")" == "$(realpath "$csource")" ]; then # Link already exists. Skip
                [ $VERBOSE -gt 0 ] && echo "Skipping $ctarget..."
            elif [ ! -L "$ctarget" -a -d "$ctarget" -a -d "$csource" ]; then # Dictionary exists. Enter
                stow "$csource" "$ctarget"
            else # No can do.
                echo "Aborting. $ctarget exists, but is not owned by dotstow"; exit 1
            fi
        else
            if [ "$SIMULATE" -gt 0 ] || ln -s "$(realpath "$csource")" "$ctarget"; then
                [ $VERBOSE -gt 0 ] && echo "Linking $ctarget to $csource"
            else
                echo "Could not link $ctarget to $csource"; exit 1
            fi
        fi
    done

    [ "$VERBOSE" -gt 1 ] && echo "Leaving $stowrepo..."
}

destow() {
    local stowrepo=$1
    local stowtarget=$2

    [ "$VERBOSE" -gt 1 ] && echo "Entering $stowrepo..."

    local files=()
    while read line; do
        if [ "$line" != "." -a "$line" != ".." ]; then
            files+=("$line")
        fi
    done < <(ls -a $stowrepo)

    [ "$VERBOSE" -gt 1 ] && echo "Filelist: ${files[@]}"

    for file in "${files[@]}"; do
        local file=$(basename "$file")
        local ctarget="$stowtarget/$file"
        local csource="$stowrepo/$file"

        if [ ! -e "$ctarget" ]; then # Target doesn't exists. skip
            [ $VERBOSE -gt 0 ] && echo "$ctarget does not exist. Skipping..."
        elif [ ! -L "$ctarget" ]; then
            if [ -d "$ctarget" -a -d "$csource" ]; then
                destow "$csource" "$ctarget"
            else
                echo "$ctarget exists, but is not owned by dotstow (Not a link)"; exit 1
            fi
        elif [ "$(readlink -f "$ctarget")" != "$(realpath "$csource")" ]; then
            [ "$VERBOSE" -gt 0 ] && echo "$(readlink -f "$ctarget")" != "$(realpath "$csource")"
            echo "$ctarget exists, but is not owned by dotstow (Wrong link)"; exit 1
        else
            if [ "$SIMULATE" -gt 0 ] || rm -f "$ctarget"; then
                [ $VERBOSE -gt 0 ] && echo "Unlinking $ctarget"
            else
                echo "Could not unlink $ctarget"; exit 1
            fi
        fi
    done

    [ "$VERBOSE" -gt 1 ] && echo "Leaving $stowrepo..."
}

restow() {
    destow "$1" "$2"
    stow "$1" "$2"
}

TARGET="$HOME"
VERBOSE=0
REPO="$(dirname $0)"
COMMAND=stow
HELP=0
SIMULATE=0

while getopts DSRvhnt: opt; do
    case $opt in
        D)
            COMMAND=destow
            ;;
        S)
            COMMAND=stow
            ;;
        R)
            COMMAND=restow
            ;;
        t)
            TARGET="$OPTARG"
            ;;
        v)
            let VERBOSE++
            ;;
        h)
            HELP=1
            ;;
        n)
            SIMULATE=1
            ;;
        \?)
            echo "Invalid option: -$OPTARG" >&2
            exit 1
            ;;
        :)
            echo "Option -$OPTARG required an argument." >&2
            ;;
    esac
done
shift $[ $OPTIND-1 ]

TARGET=${TARGET/%\//} # Remove trailing slashes

if [ "$HELP" -eq 1 -o "${#@}" -eq 0 ]; then
    echo -e "Usage: ./dotstow.sh [-DSRvhn] [-t target] stows..."
    echo -e "\t-D: Destow"
    echo -e "\t-S: Stow"
    echo -e "\t-R: Restow"
    echo -e "\t-t: target folder (default ~)"
    echo -e "\t-v: verbose"
    echo -e "\t-h: show this help"
    echo -e "\t-n: simulated/dry-run"
    echo -e "\tstows: stow folders relative to dotstow.sh"
fi

for stow in $@; do
    if [ ! -d "$REPO/$stow" ]; then
        echo "Stow $stow not found." >&2
        exit 2
    fi
    $COMMAND "$REPO/$stow" "$TARGET"
done

[ "$SIMULATE" -gt 0 ] && echo "Warning: Simulated. No actual changes to the filesystem have been done."