#!/bin/bash
# Copyright 2025 The Fuchsia Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

#### CATEGORY=Other
### Create a pair of changes that will be submitted atomically. It will modify
### the top commit in fuchsia.git and in another repository (vendor/google by
### default), and make them depend on each other.

## usage: fx atomic-commit [--no-upload] [--repo <path>]
##
##   --no-upload    Amend the commits but don't push them.
##   --repo <path>  Path of the other repository, relative to the Fuchsia
##                  checkout. Defaults to vendor/google. The repository must
##                  support circular dependencies with fuchsia.git, e.g.
##                  third_party/cobalt_config.

set -o errexit

source "$(cd "$(dirname "${BASH_SOURCE[0]}")" >/dev/null 2>&1 && pwd)"/lib/vars.sh
fx-config-read

function update_footer() {
    local repo_dir=$1
    local dependency_id=$2
    local upload=$3
    (
        cd "${repo_dir}" || exit 1
        local message=$(git log -1 --pretty=%B)
        local new_footer="""Depends-on: ${dependency_id}
Change-Id:"""

        local modified_message=${message/"Change-Id:"/${new_footer}}
        git commit --amend -m "${modified_message}"
        if [[ "${upload}" == "true" ]]; then
            git push origin
        fi
    )
}

# Prints the Gerrit host short name (e.g. "fuchsia" or "turquoise-internal")
# of the repository's origin remote.
function gerrit_host() {
    local repo_dir=$1
    git -C "${repo_dir}" config --get remote.origin.url |
        sed -E 's#^[a-z]+://([^/.]+).*#\1#'
}

# Prints the `Depends-on` value for the top commit of `dep_dir`, as seen from a
# CL in `repo_dir`. The Gerrit host prefix is only needed if the two
# repositories are on different hosts.
function dependency_id() {
    local repo_dir=$1
    local dep_dir=$2
    local change_id=$(
        cd "${dep_dir}"
        git log -1 | grep "Change-Id" | sed "s/Change-Id://g" | xargs
    )
    local dep_host=$(gerrit_host "${dep_dir}")
    if [[ "$(gerrit_host "${repo_dir}")" == "${dep_host}" ]]; then
        echo "${change_id}"
    else
        echo "${dep_host}:${change_id}"
    fi
}

function print_usage_guidance() {
    local other_repo=$1
    echo
    echo "To create atomic-commit, make sure your changes are on the top of"
    echo "commit stacks in both fuchsia and ${other_repo}."
    echo
    echo "--- Current top commit in fuchsia.git ---"
    echo
    echo $(cd $FUCHSIA_DIR && git log -1 --pretty=medium)
    echo
    echo "--- Current top commit in ${other_repo} ---"
    echo
    echo $(cd ${FUCHSIA_DIR}/${other_repo} && git log -1 --pretty=medium)
    echo
    read -p "Does this look correct to you?[y|n]" value

    if [[ "${value}" != "y" && "${value}" != "Y" ]]; then
        exit
    fi
}

function print_tip() {
    local upload=$1
    echo
    echo "Your changes are raised."
    if [[ "${upload}" == "true" ]]; then
        echo "Please enable Auto-Submit on both CLs to enable atomic-commit."
    else
        echo "Changes were not uploaded (--no-upload)."
        echo "You will need to manually push them to enable atomic-commit."
    fi
    echo
}

main() {
    local upload="true"
    local other_repo="vendor/google"
    while [[ $# -gt 0 ]]; do
        case "$1" in
            --no-upload)
                upload="false"
                ;;
            --repo)
                if [[ $# -lt 2 ]]; then
                    echo "--repo requires a path"
                    exit 1
                fi
                other_repo="${2%/}"
                shift
                ;;
            *)
                echo "Unknown option: $1"
                exit 1
                ;;
        esac
        shift
    done

    local other_dir="${FUCHSIA_DIR}/${other_repo}"
    if ! git -C "${other_dir}" rev-parse --git-dir >/dev/null 2>&1; then
        echo "${other_repo} is not a git repository in ${FUCHSIA_DIR}"
        exit 1
    fi

    print_usage_guidance "${other_repo}"

    local dep_on_fuchsia=$(dependency_id "${other_dir}" "${FUCHSIA_DIR}")
    local dep_on_other=$(dependency_id "${FUCHSIA_DIR}" "${other_dir}")

    update_footer "${other_dir}" "${dep_on_fuchsia}" "${upload}"
    update_footer "${FUCHSIA_DIR}" "${dep_on_other}" "${upload}"

    print_tip "${upload}"
}

main "$@"