#!/bin/bash
#
# To start tracking a file,
#   cp ~/.screenrc dot/screenrc
#
# To sort out symlinks when things are clean
#   infra/makelinks install

set -e -o posix -o pipefail

badusage () {
    echo >&2 "usage: $0 [-n|-v] list|setup|import|clean"
    exit 18
}

real_act=''

while true; do
    if [ $# = 0 ]; then break; fi
    case "$1" in
    -n) real_act=log_only ;;
    -v) real_act=with_log ;;
    -*) badusage ;;
    *) break ;;
    esac
    shift
done

case "$#.$1" in
1.list|1.setup|1.import|1.clean) ;;
*)  badusage ;;
esac

mode=$1; shift

dots=$( find dot -type f -name '[0-9a-zA-Z]*[0-9a-zA-Z]' )

basepath=$(pwd)
basepath=${basepath#$HOME/}

estatus=0

show () {
    printf "%s\n" "$1"
}

good () {
    if [ $mode = list ]; then
	show "good: $dot: $1"
    fi
}

bad () {
    estatus=16
    show "bad: $dot: $1" >&2
}

needs () {
    if [ $mode = $1 ]; then
	act=$real_act
    else
	show "needs $1: $prhome: $2"
	act=:
    fi
}

log_only () {
    echo "x $*"
}

with_log () {
    log_only "$@"
    "$@"
}

for dot in $dots; do
    underhome=".${dot#dot/}"
    inhome="$HOME/$underhome"
    prhome="~/$underhome"
    if [ "$inhome" -ef "$dot" ]; then
	good "already symlinked here"
    elif [ -h "$inhome" ]; then
        bad "wrong symlink target"
    elif ! [ -e "$inhome" ]; then
	needs setup "absent here"
	$act ln -s "$basepath/$dot" "$inhome"
    elif [ -f "$inhome" ] && cmp -s "$dot" "$inhome"; then
	needs setup "identical here but not yet symlinked"
	$act rm -f "$inhome"~
	$act ln -s "$basepath/$dot" "$inhome"~
	$act mv -f "$inhome"~ "$inhome"
    else
	needs import "modified here"
	$act rm -f "$dot"~
	$act cp "$inhome" "$dot"~
	$act mv -f "$dot"~ "$dot"
    fi
done

brokens=$(
    cd $HOME
    find -L .[0-9a-zA-Z]* -xdev -type l -lname "$basepath/dot/*"
)
for underhome in $brokens; do
    inhome="$HOME/$underhome"
    prhome="~/$underhome"
    needs clean "symlink to removed file in dot/"
    $act rm -f "$inhome"
done