#!/bin/bash

set -e

if [ "$1" = "-batch" ]; then
    shift
    interactive=0
elif [ -t 1 ]; then
    interactive=1
else
    interactive=0
fi

if [ $# -lt 1 -o $# -gt 3 ]; then
    cat <<EOF
Usage: $0 [-batch] archive.tar.gz [git_url [git_branch]]
EOF
    exit 1
fi

archive=$1
if [ ! -r "$archive" ]; then
    printf 'File not found: %s\n' "$archive"
    exit 1
fi

if [ $# -ge 2 ]; then
    giturl=$2
    gitbranch=${3:-master}
else
    giturl=$(git rev-parse --show-toplevel)
    gitbranch=$(git branch | sed -n '/^\*/{s/^..//;p;}')
fi

tmpdir=$(mktemp -d)
trap "rm -fr \"$tmpdir\"" EXIT

arch_dir="$tmpdir/a"
git_dir="$tmpdir/b"

myname=$(type -p "$0")
case "$myname" in
    /*)
        exclude="$myname.exclude"
        ;;
    *)
        exclude="$PWD/$myname.exclude"
        ;;
esac

if [ ! -r "$exclude" ]; then
    printf 'File not found: %s\n' "$exclude"
    exit 1
fi

echo "Exclude patterns extracted from file: $exclude"

echo "Extracting archive: $archive -> $arch_dir"
tar --directory "$tmpdir" \
    --transform 's!^[^/]*!a!' \
    --extract --gunzip --file "$archive"

echo "Copying git repository: $giturl/$gitbranch -> $git_dir"
git archive --format=tar --prefix="b/" --remote="$giturl" "$gitbranch" \
    | tar --directory "$tmpdir" --extract --file -

fa=from_tgz
fb=from_git
cd "$tmpdir"

sed -n '/^-/{s/^- //;p;}' "$exclude" > ea
sed -n '/^+/{s/^+ //;p;}' "$exclude" > eb

find a -type f \
    | sed 's!^a/!!' \
    | grep -E -v -x -f ea \
    | sort > "$fa"
find b -type f \
    | sed 's!^b/!!' \
    | grep -E -v -x -f eb \
    | sort > "$fb"

diffcmd() {
    diff -u "$fa" "$fb"
}

colordiff=$(type -p colordiff)
colorless() {
    if [ -n "$colordiff" ]; then
        "$colordiff" | less -R -F
    else
        less -F
    fi
}

if [ "$interactive" = "1" ]; then
    diffcmd | colorless
else
    diffcmd
fi