composer

#!/bin/bash

COMPOSERX_HOME=$HOME/.composerx
COMPOSERX_BIN=$COMPOSERX_HOME/bin
COMPOSERX_EXECUTABLE=$COMPOSERX_HOME/bin/composer

function __download_setup_php() {
    # See:
    #   How do I install Composer programmatically? - Composer
    #   https://getcomposer.org/doc/faqs/how-to-install-composer-programmatically.md
    EXPECTED_CHECKSUM="$(php -r 'copy("https://composer.github.io/installer.sig", "php://stdout");')"
    php -r "copy('https://getcomposer.org/installer', 'composer-setup.php');"
    ACTUAL_CHECKSUM="$(php -r "echo hash_file('sha384', 'composer-setup.php');")"

    if [ "$EXPECTED_CHECKSUM" != "$ACTUAL_CHECKSUM" ]
    then
        >&2 echo 'ERROR: Invalid installer checksum'
        rm composer-setup.php
        exit 1
    fi
}

function __rm_setup_php() {
    rm -f composer-setup.php
}

function __install_composer() {
    if [ ! -f $COMPOSERX_EXECUTABLE ]; then
        if [ -f composer-setup.php ]; then
            >&2 echo 'ERROR: Delete the existing composer-setup.php file before running this script'
            exit 1
        fi

        __download_setup_php
        trap __rm_setup_php EXIT

        mkdir -p $COMPOSERX_BIN
        php composer-setup.php --quiet --install-dir=$COMPOSERX_BIN --filename=composer
    fi
}

function __main() {
    __install_composer
    $COMPOSERX_EXECUTABLE "$@"
}

__main "$@"