#!/usr/bin/env bash
# SPDX-License-Identifier: Apache-2.0
# Copyright (C) 2021 Arm Limited or its affiliates and Contributors. All rights reserved.

[[ "$TRACE" ]] && set -x
set -euo pipefail

print_help() {
    echo 'Usage: git-list-between BRANCH MM/DD/YYYY MM/DD/YYYY [[--] <path>...]'
}

list() {
    ARGS=(
        # Don't follow the other side of merges.
        --first-parent
        # Commit order.
        --topo-order
        --reverse
        '--abbrev=15'
        "--since=$DATE_LOWER"
        "--until=$DATE_UPPER"
        "$BRANCH"
    )
    TZ=UTC git log "${ARGS[@]}" "$@"
}

main() {
    BRANCH="$1"
    DATE_LOWER="$2"' 00:00:00 UTC'
    DATE_UPPER="$3"' 00:00:00 UTC'
    EXTRA_ARGS=("${@:4}")

    # Validate args
    git rev-parse "$BRANCH" 1>/dev/null \
        && date -d "$DATE_LOWER" 1>/dev/null \
        && date -d "$DATE_UPPER" 1>/dev/null \
        || {
            print_help
            exit 1
        }

    # Read the list of commits without passing EXTRA_ARGS
    # This prevents the list from being filtered by a PATHSPEC...
    readarray -t COMMIT_LIST < <(list '--format=format:%H')
    # Create a hashmap [SHA=>index] that contains the indexes of the commits in
    # the selected time span.
    declare -A INDEX_LOOKUP=()
    for i in "${!COMMIT_LIST[@]}"; do
        INDEX_LOOKUP["${COMMIT_LIST[$i]}"]=$i
    done

    # Construct the final list by passing EXTRA_ARGS, allowing the user to filter
    # the commits by a PATHSPEC..., use the index of the commit in the unfiltered
    # log, and format the output
    while read -r SHA ABBREV DATE TIME; do
        INDEX="${INDEX_LOOKUP["$SHA"]}"
        printf '%s %s-%05dT%s-%s\n' "$SHA" "$DATE" "$((INDEX+1))" "$TIME" "$ABBREV"
    done < <(list \
        '--date=format-local:%Y%m%d %H%M%S' \
        '--format=format:%H %h %cd' \
        "${EXTRA_ARGS[@]}")
}

case "${1:--h}" in
    -h | --help)
        print_help
        [ $# -ne 0 ]
        exit $?
        ;;
    *)
        main "$@"
        ;;
esac