#!/usr/bin/env sh
here="$(readlink -f "$0")" && here="${here%/*}" && CDPATH= cd "$here" || exit
#remote="https://github.com/notwa/rc/archive/master.tar.gz"
remote="https://eaguru.guru/git/notwa/rc/archive/master.tar.gz"

# NOTE: this script only updates files in subdirectories.
#       it does not update itself!

warn() {
    printf >&2 %s\\n "$*"
}

do_clean() { true; }

clean() {
    do_clean || warn 'update: failed to remove temporary files'
    do_clean() { true; }
}

die() {
    warn "update:" "$@"
    clean
    exit 1
}

! [ -d .git ] || die "you don't need this script when you have .git!"
! [ -e _new ] || die '"_new" already exists, please remove it before updating'

backup="backup-$(date -u +%s)" || die 'failed to determine date'

# load libraries.
# TODO: write a simple fallback when the library is missing!
dummy() { :; }
preload=dummy
. sh/obtain

__obtain_prep

do_clean() { rm dummy; }

if ! __obtain_url https://eaguru.guru/t/dummy > dummy; then
    __obtain_bootstrap || die
    __obtain_url https://eaguru.guru/t/dummy > dummy || die
fi

do_clean() { rm dummy dummy.sha256sum; }

printf >dummy.sha256sum '%s *%s\n' \
1b577383bcfb9f191c785497f4ac34a8fb546807bd1094ef65d0ce9a5a63423e dummy ||
die 'failed to write file'

if ! sha256sum -c dummy.sha256sum >/dev/null; then
    die 'failed to validate dummy file'
fi

clean

do_clean() { rm update.tar.gz; }

if ! __obtain_url "$remote" > update.tar.gz; then
    die 'failed to download new version'
fi

do_clean() { rm -r update.tar.gz _new_$$; }

mkdir _new_$$ || die 'failed to create temporary directory'
tar zxf update.tar.gz -C _new_$$ || die 'failed to extract update files'
rm update.tar.gz || die 'failed to remove archive file'

rename() {
    if [ -d _new_$$/rc-master ]
    then mv _new_$$/rc-master _new
    else mv _new_$$/rc _new
    fi
}

do_clean() { if [ -d _new ]; then rm -r _new_$$ _new; else rm -r _new_$$; fi; }

if ! rename; then
    die 'failed to move update files'
fi

do_clean() { rm -r _new _new_$$; }

rmdir _new_$$ || die

discover() {
    find "$1" "_new/$1" -type f -exec sha256sum -- {} +
}

different() {
    awk '
{
    k = substr($0, 67)
    sub("^_new/", "", k)
    if (a[k]) {
        if (a[k] != $1) print k
        delete a[k]
    } else a[k] = $1
}
END {for (k in a) print k}'
}

do_clean() { rm -r _new; }

desire() {
    case "$f" in
    (*.bak) false;;
    (*/.git/*) false;;
    (vim/.netrwhist/*) false;;
    (vim/backup/*) false;;
    (vim/bundle/*) false;;
    (vim/swp/*) false;;
    (vim/undo/*) false;;
    (*) true
    esac
}

backup() {
    for f; do
        if ! [ -d "$backup/${f%/*}" ]; then
            mkdir -p -- "$backup/${f%/*}" ||
            die 'failed to create backup directory'
        fi
        ! [ -f "$backup/$f" ] || die 'backup file already exists'
        cp -- "$f" "$backup/$f" || die 'failed to create backup file'
    done
}

for d in home sh vim; do
    if ! discover "$d" > _new/hashes.txt; then
        die 'failed to find new files'
    fi

    if ! different < _new/hashes.txt > _new/updates.txt; then
        die 'failed to compare files'
    fi

    if ! LC_ALL=C sort < _new/updates.txt > _new/sorted.txt; then
        die 'failed to sort file paths'
    fi

    while read -r f; do
        desire "$f" || continue

        if [ -f "_new/$f" ] && ! [ -f "$f" ]; then
            warn " +  $f"
            cp "_new/$f" "$f"
        elif ! [ -f "_new/$f" ] && [ -f "$f" ]; then
            warn " -  $f"
        elif [ "_new/$f" -nt "$f" ]; then
            # NOTE: this does not play well with git --patch.
            #       don't use this script when you have git!
            warn " *  $f"
            backup "$f"
            cp "_new/$f" "$f"
        elif [ "_new/$f" -ot "$f" ]; then
            warn " /  $f"
        #else warn " =  $f"
        fi
    done < _new/sorted.txt
done

clean