#!/bin/sh -e

# Created by Robert Grønning <slimg@iggu.org>

# Usage info
show_help() {
cat << EOF
Usage: ${0##*/} SOURCE DESTINATIONFOLDER

This script will help you to make SOURCE a symbolic link
pointing toward the actual data residing in DESTINATIONFOLDER.
EOF
}

SRC=${1%/}
DSTDIR=${2%/}

# Make sure both parameters are filled in
if [ -z "$SRC" ] || [ -z "$DSTDIR" ]; then
    show_help
    exit 0
fi

NAME=$(basename "$SRC")
DST=$DSTDIR/$NAME

# Make sure both aren't missing
if [ ! -e "$SRC" ] && [ ! -e "$DST" ]; then
    echo 'ERROR: Neither exist.'
    echo
    show_help
    exit 1
fi

# Make sure DSTDIR exist
if [ -e "$SRC" ] && [ ! -e "$DSTDIR" ]; then
    echo 'WARNING: The following folder does not yet exist:'
    echo "  $DSTDIR"
    echo
    echo 'Do you want to create it? (y|n) :'
    read -r REPLY
    if [ "$REPLY" = y ]; then
        echo
        echo "Running: mkdir -p \"$DSTDIR\""
        mkdir -p "$DSTDIR"
    else
        echo
        echo "\"y\" was not received. Aborting."
        exit 0
    fi
fi

# Make sure DSTDIR is a directory
if [ ! -d "$DSTDIR" ]; then
    echo 'ERROR: The following is not a directory:'
    echo "         $DSTDIR"
    echo
    show_help
    exit 1
fi

# Make sure SRC is not a symbolic link
if [ -h "$SRC" ]; then
    echo 'ERROR: The following is already a symbolic link:'
    echo "         $SRC"
    echo
    show_help
    exit 1
fi

# Create symbolic link when only DST exist
if [ -e "$DST" ] && [ ! -e "$SRC" ]; then
    echo "Running: ln -s \"$DST\" \"$SRC\""
    ln -s "$DST" "$SRC"
    exit 0
fi

# Create symbolic link when only SRC exist
if [ ! -e "$DST" ] && [ -e "$SRC" ] && [ ! -h "$SRC" ]; then
    echo "Running: mv \"$SRC\" \"$DST\""
	mv "$SRC" "$DST"
    echo "Running: ln -s \"$DST\" \"$SRC\""
    ln -s "$DST" "$SRC"
    exit 0
fi

# Create symbolic link when both SRC and DST exist
if [ -e "$DST" ] && [ -e "$SRC" ] && [ ! -h "$SRC" ]; then
    echo 'WARNING: Both exist.'
    echo
    echo 'Options:'
    echo "  d: Sacrifice \"$SRC\""
    echo "  s: Sacrifice \"$DST\""
    echo "  n: Don't do anything."
    echo
    echo "What do you want to do? (d|s|n) :"
    read -r REPLY
    case "$REPLY" in
        d )
            echo
            echo "Running: rm -R \"$SRC\""
            rm -R "$SRC"
            echo "Running: ln -v -s \"$DST\" \"$SRC\""
            ln -v -s "$DST" "$SRC"
            exit 0
            ;;
        s )
            echo
            echo "Running: rm -R \"$DST\""
            rm -R "$DST"
            echo "Running: mv \"$SRC\" \"$DST\""
            mv "$SRC" "$DST"
            echo "Running: ln -s \"$DST\" \"$SRC\""
            ln -s "$DST" "$SRC"
            exit 0
            ;;
        * )
            exit 1
            ;;
    esac
fi