#!/bin/bash

trap 'echo "ERROR at line ${LINENO} (code: $?)" >&2' ERR
trap 'echo "Interrupted" >&2 ; exit 1' INT

set -o errexit
set -o nounset

# Ensure all alr runs are non-interactive
alias alr="alr -n"

# Detect changes
CHANGES=$(git diff --name-only HEAD~1)

# Bulk changes for the record
echo Changed files: $CHANGES

# Disable assistant. This is necessary despite the setup-alire action doing it
# too, because we sometimes run inside a Docker with fresh configuration
alr toolchain --disable-assistant

# Configure index
alr index --del local >/dev/null || true # Simplifies local testing
alr index --name local --add ./index

# Remove community index in case it has been added before
alr index --del community >/dev/null || true

diff_opts=(--minimal -U0 --line-prefix "--| " --ignore-all-space --ignore-blank-lines --ignore-cr-at-eol)

function diff_one() {
    local file="$1"
    local folder=$(dirname $file)
    local crate=$(basename $file .toml | cut -f1 -d-)
    local version=$(basename $file .toml | cut -f2- -d-)
    local milestone="$crate=$version"

    echo " "
    echo "------8<------"

    if echo $milestone | grep -q external; then
        echo DIFFING external: $milestone
        git diff "${diff_opts[@]}" HEAD~1 -- $file
    else
        echo DIFFING release: $milestone

        # Locate the immediately precedent release

        # For a first release, there's nothing to compare
        if [ $(ls $folder | grep -v external | wc -l) -eq 1 ]; then
            echo NOTHING to diff against, first crate release
            return 0
        fi

        # Othewise, get from alr what's the immediately preceding version
        local prev_milestone=$(alr show "$crate<$version" | head -1 | cut -f1 -d:)
        echo DIFFING milestones $prev_milestone '-->' $milestone

        if [ "$prev_milestone" == "ERROR" ]; then
            echo ERROR extracting milestone:
            alr show "$crate<$version"
            return 1
        fi

        # Convert into filename
        local prev_file=$folder/${prev_milestone//=/-}.toml

        git diff --no-index "${diff_opts[@]}" -- $prev_file $file
    fi

    return 0
}

for file in $CHANGES; do
    diff_one "$file" || true # keep on trying for different files
done