Diffs the revisions in chap

diff-chap-revs.sh

#!/usr/bin/env sh

# This script requires difftastic and toml-cli, which can be installed by `cargo install`

pkg=$2
version=$3
what_to_do=$1

if [ ! -d _sources/$pkg/$version ]; then
    echo "Package $pkg and/or version $version doesn't exist"
    exit 1
fi

ghub=$(toml get _sources/$pkg/$version/meta.toml github.repo | cut -d "\"" -f 2)
repo_name=$(echo $ghub | cut -d'/' -f 2)
subdir=$(toml get _sources/$pkg/$version/meta.toml subdir | cut -d "\"" -f 2)
grev=$(toml get _sources/$pkg/$version/meta.toml github.rev | cut -d "\"" -f 2)
revs=$(toml get _sources/$pkg/$version/meta.toml revisions | jq ".[] | .number" | sort)

checkout () {
    if [ ! -d "$repo_name" ]; then
        git clone "https://github.com/$ghub"
    fi
    ( (cd "$repo_name" && git fetch --all && git checkout $grev) >/dev/null 2>&1)
    echo "Checked out $repo_name at commit $grev"
}

apply_rev () {
    cp "_sources/$pkg/$version/revisions/$rev.cabal" "$repo_name/$subdir/$pkg.cabal"
    ( cd "$repo_name" && git add $subdir/$pkg.cabal && git commit -m "rev $rev")
}

read_a_key() (
  exec </dev/tty
  t=$(stty -g)
  trap 'stty "$t"; return' EXIT INT QUIT TERM
  stty raw -echo isig
  dd count=1 2>/dev/null
)

apply_rev_and_diff () {
    rev=$1
    echo "Diffing revision $rev, press something to continue..."
    read_a_key >/dev/null
    cp "_sources/$pkg/$version/revisions/$rev.cabal" "$repo_name/$subdir/$pkg.cabal"
    ( cd "$repo_name" && GIT_EXTERNAL_DIFF=difft git diff && git add $subdir/$pkg.cabal && git commit -m "rev $rev" >/dev/null 2>&1)
}

apply_up_to () {
    for rev in $revs; do
        if [ $rev -eq $1 ]; then
            break
        fi
        apply_rev $rev
    done
}

apply_and_diff_starting () {
    for rev in $revs; do
        if [ $rev -lt $1 ]; then
            continue
        else
            apply_rev_and_diff $rev
        fi
    done
}

case $what_to_do in
    last)
        checkout
        last=$(echo "$revs" | tail -n1)
        apply_up_to $last
        apply_and_diff_starting $last
        ;;
    diff_from)
        checkout
        apply_up_to $4
        apply_and_diff_starting $4
        ;;
    diff_all)
        checkout
        apply_and_diff_starting 1
        ;;
    *)
        printf "Options are:\n\t- last: diffs the last revision\n\t- diff_from: diffs from the provided revision\n\t- diff_all: diffs all the revisions\n"
        ;;
esac