format

#!/bin/bash

set -euo pipefail

# Run rustfmt on our code. Suitable for use in editor integrations as well as in
# CI.
#

# By setting this environment variable (as opposed to using the `+toolchain`
# syntax in the `cargo` command), we can automatically install the given
# toolchain if it doesn't already exist on the system. It'll take a while to
# download the first time, but thereafter, it will be quick!
#
# Note that you will need your Rustup profile set to something higher
# than "minimal" (e.g., "default"), since `rustfmt` isn't included in
# "minimal".
export RUSTUP_TOOLCHAIN="nightly-2022-11-02"

# Default to checking formatting in the absence of any options.
mode="check"

while (("$#")); do
    case "$1" in
        -e | --editor)
            mode="editor"
            shift
            ;;
        -c | --check | --ci)
            mode="check"
            shift
            ;;
        -u | --update)
            mode="update"
            shift
            ;;
        -h | --help)
            mode="help"
            shift
            ;;
    esac
done

if [ "${mode}" == "help" ]; then
    cat >&2 << EOF

    Usage: $0 <OPTIONS>

    Options:

    -c|--check|--ci: Check the formatting of all Rust code. Use this
    in CI jobs. If no other options are given, this is the default
    behavior.

    -e|--editor: Run rustfmt on the contents of a file passed on
    standard input; returns formatted code on standard output. Use
    this for local editor integrations.

    -h|--help: Print this help message.

    -u|--update: Format all Rust code. Use this after updating the
    nightly version of Rust used for formatting, updating
    configuration options, or any other time you just want to make
    sure all the code is up to date.
EOF
    exit
fi

if [ "${mode}" == "editor" ]; then
    # Pass the contents of an individual file on standard input and
    # write formatted code back to standard output.
    rustfmt < /dev/stdin
    exit $?
fi

if [ "${mode}" == "update" ]; then
    echo >&2 "$0: Updating all Rust code formatting"
    cargo fmt --all
    exit $?
fi

echo >&2 "$0: Checking all Rust code formatting"
cargo fmt --all -- --check