#!/usr/bin/env sh

if [ -n "${CI}" ]; then
    printf "This script should not be used on CI\n"
    exit 1
fi

if [ -e Makefile ]; then
    printf "A Makefile already exists! Refusing to clobber\n"
    exit 1
fi

# Ensure there's an EMACS_VERSION
if [ -z "${EMACS_VERSION}" ]; then
    printf "Please set EMACS_VERSION in your ~/.profile or similar\n"
    printf "and then re-run this script.\n\n"
    printf "Example:\n\n"
    printf "  echo 'EMACS_VERSION=26.1' >> ~/.profile\n\n"
    printf "You can determine your Emacs version with \`emacs --version'.\n"
    exit 1
fi

# Retrieve the package basename
if [ -z "${PACKAGE_BASENAME}" ]; then
    read -p "Package basename: " PACKAGE_BASENAME
    if [ -z "${PACKAGE_BASENAME}" ]; then
        printf "Quit\n"
        exit 1
    fi
else
    printf "Using PACKAGE_BASENAME=${PACKAGE_BASENAME}\n"
fi

# Determine most recent SHA1 and download that Makefile
printf "Determining latest version of EMake..."
EMAKE_SHA1=$(curl -fsSL "https://api.github.com/repos/vermiculus/emake.el/git/refs/heads/master" \
    | grep -oE '"sha"\s*:\s*"([[:alnum:]]+)"' \
    | cut -d\" -f4)
EMAKE_SHA1_SHORT=$(echo ${EMAKE_SHA1} | cut -c1-7)
printf "${EMAKE_SHA1_SHORT}\n"
printf "Downloading EMake..."
curl -fsSLO "https://raw.githubusercontent.com/vermiculus/emake.el/${EMAKE_SHA1}/emake.mk"
printf "done\n"

# Finish up
printf "Generating Makefile..."
cat <<EOF > Makefile
EMAKE_SHA1            ?= ${EMAKE_SHA1}
PACKAGE_BASENAME      := ${PACKAGE_BASENAME}

PACKAGE_ARCHIVES      := gnu melpa

include emake.mk

.DEFAULT_GOAL: help

emake.mk: ## download EMake's default driver
        curl -fsSkL "https://raw.githubusercontent.com/vermiculus/emake.el/\$(EMAKE_SHA1)/emake.mk"

clean: ## clean compiled lisp and EMake files
	rm -rf \$(EMAKE_WORKDIR)
	rm -f \$(PACKAGE_LISP:.el=.elc)
EOF
printf "done\n"

printf "\nYou now have EMake version ${EMAKE_SHA1_SHORT}!\n"
printf "This is the most recent stable version.\n"
printf "Run \`make help' now to test your installation and to see what you've got!\n"
printf "\nIf you need to install Emacs on CI services, see the manual on GitHub\n"
printf "for a convenient one-liner.\n"