#!/usr/bin/env bash

SCRIPT="$(basename "$0")"

long='help,verbose,quiet,force,dry-run'
short='hvqfn'

eval set -- "$(getopt -o $short -l $long -n "$SCRIPT" -- "$@")"

help() {
    cat <<-EOF
$SCRIPT
Toby Vincent <tobyv13@gmail.com>

$SCRIPT
    Creates symbolic links (for files) or junctions (for directories) from the
    windows filesystem to the WSL2 instance using mklink.exe.

USAGE:
    $SCRIPT [OPTIONS] <SOURCE> [TARGET]

OPTIONS:
    -h, --help      Show this message
    -v, --verbose   Show more output
    -q, --quiet     Suppress all output
    -f, --force     Overwrite items
    -n, --dry-run   Write output of commands with running them.

ARGS:
    SOURCE (required)
        Path to the source file or directory the link should point to.

    TARGET (optional)
        Path to the location to create the link. [Default: $PWD]
EOF
}

say() {
  if ! $quiet; then
    printf "%s: %s\n" "$SCRIPT" "$@"
  fi
}

say_verbose() {
  if $verbose; then
    say "$@"
  fi
}

say_err() {
  say "$@" >&2
}

err() {
  # shellcheck disable=SC2145
  say_err "ERROR: $@"
  exit 1
}

err_help() {
  help
  err "$*"
}

run() {
  if $is_dry_run; then
    say "DRYRUN: $*"
    return 0
  fi
  
  say_verbose "running: $*"

  if $quiet; then
    "$@" &>/dev/null
  else
    say "$("$@")"
  fi
}

need() {
  for cmd in "$@"; do
    if ! command -v "$cmd" >/dev/null 2>&1; then
      err "need $cmd (command not found)"
    fi
  done
}

trg=$PWD
verbose=false
quiet=false
force=false
is_dry_run=false
while true; do
  case "$1" in
    -h | --help)
      help
      exit 0
    ;;
    -v | --verbose)
      verbose=true
      shift
    ;;
    -q | --quiet)
      quiet=true
      shift
    ;;
    -f | --force)
      force=true
      shift
    ;;
    -n | --dry-run)
      is_dry_run=true
      shift
    ;;
    --)
      shift
      break
    ;;
    *)
      break
    ;;
  esac
done

need powershell.exe
need realpath

case "$#" in
  0) err_help "must provide at least 1 argument";;
  1) src="$1"; trg="$PWD"; shift;;
  2) src="$1"; trg="$2"; shift 2;;
  *) err_help "too many arguments"
esac

while test -L "$src"; do
  tmp="$src"
  src=$(realpath "$src")
  say_verbose "resolved symbolic link $tmp -> $src"
done

if ! test -e "$src"; then
  err "$src does not exist."
fi

if test -d "$src"; then
  say_verbose "$src is a directory. Switching to directory symbolic link."
  args='/D'
fi

trg_name=$(basename "$trg")
trg_dir=$(dirname "$trg")

if ! test -d "$trg_dir"; then
  mkdir -p "$trg_dir"
  say_verbose "created directory $trg_dir"
fi

win_src=$(wslpath -w "$src")
win_trg=$(wslpath -w "$trg_dir")\\"$trg_name"

old_trg="$(powershell.exe "(Get-Item $win_trg).FullName" 2>/dev/null)"
old_src="$(powershell.exe "(Get-Item $win_trg).Target" 2>/dev/null)"

old_src="${old_src/*wsl$/}"
new_src="${win_src/*wsl$/}"

if ! $force && test "${old_src#*"$new_src"}" != "$old_src"; then
  say_verbose "symbolic link already exists."
  exit 0
fi

say_verbose "$(cat <<-EOF 
linking:
  WSL paths:
    target: $trg
    source: $src
  Win paths: 
    target: $win_trg
    source: $win_src
EOF
)"

if test "$old_trg" != ''; then
  if $force; then
    say_verbose "$(cat <<-EOF 
$win_trg already exists. Overwriting.
  target: $win_trg
  source: $old_src
EOF
)"
    rm -rf "$trg"
  else
    err "$(cat <<-EOF 
$win_trg already exists.
  Existing file: 
    target: $win_trg
    source: $old_src

  Use -f or --force to overwrite.
EOF
)"
  fi
fi

run powershell.exe "cd ~; cmd /c mklink $args $win_trg $win_src"