setup

#!/bin/sh

# Setup an account on a new machine.
# Create symbolic links in $HOME to all entries in this directory except
# those listed in denylist.  All links created in $HOME will have a .
# prepended if the name here does not contain a leading .

# This script attempts to get bash-completions from github.

err() { printf "%s${1:+\n}" "$@"; } >&2
die() { err "$@"; exit 1; }
warn() { err "$@"; }

find_md5_executable() {
	for MD5 in md5sum md5; do $MD5 > /dev/null </dev/null 2>&1 && break; done
}

establish_context() {
	{
		base=$(dirname "$(realpath "$0" || readlink -f "$0" ||
			{ cd "$(dirname "$0")" && pwd -P | sed -e 's@$@/foo@'; }
		)");
	} 2> /dev/null

	cd "$HOME" || die
}

parse_arguments() {
	unset force
	while test $# -gt 0; do
	       case $1 in
	       -f)  force=1;;
	       *)   die unexpected argument: $1;;
	       esac
	       shift
	done
}

validate_md5_sums() {
	unset abort
	for file in $targets; do
		if test -f "$file" && test "$($MD5 < "$HOME/$file")" != \
				"$($MD5 < "$base/$file")"; then
			warn "$file is different; staging in \$HOME"
			git add "$file"
			abort=1
		fi
	done
	if test -n "$abort"; then
		if test -z "$force"; then
			die "-f to force overwrite"
		fi
		warn overwriting
	fi
}

init() {
	find_md5_executable
	establish_context  # Changes directory to $HOME
	parse_arguments "$@"
	setup_git
	targets=$(ls -a "$base" | awk 'NR==FNR {a[$0] = 1; next} ! ($0 in a)' "$base/denylist" -)
	validate_md5_sums
	mkdir -p "$HOME"/.bash-history-dir || die
	mkdir -p "$HOME"/.config/ctags || die
	ln -fs "$HOME"/.ctags "$HOME"/.config/ctags/base.ctags || die
	ln -fs "$base"/config/vim "$HOME"/.config/vim || die
	ln -fs "$base"/config/git "$HOME"/.config/git || die
}

create_symlinks() {
	for file in $targets; do
		ln -sf "$base/$file" .${file#.} || die
	done
}

create_file() {
	# Create files that should be local to this machine
	mkdir -p "$(dirname "$1")" || return 1
	if ! test -f "$1"; then
		cat > "$1"
	elif diff "$1" - | grep -q .; then
		warn "$1 already exists; not modifying"
	fi
	test -z "$NO_GIT" && git add "$1"
}

setup_git() {
	local verbose
	if test -z "$UNAME"; then
		verbose=1
		UNAME=$(id -F "$USER" 2> /dev/null)
	fi
	for n in EMAIL UNAME; do
		eval v=\$$n;
		if test -z "$v"; then
			printf "$n not set in environment.  Enter value: "
			eval read $n
		fi
	done

	( NO_GIT=1 create_file .gitconfig-local ) <<- EOF
	[user]
		email = ${EMAIL?}
		name = ${UNAME?}
	EOF
	if git rev-parse --is-inside-work-tree > /dev/null 2>&1; then
		if ! git diff-index --quiet HEAD --; then
			die '$HOME is a dirty git repo.  Aborting'
		fi
	else
		git init -b main
	fi
	git add .gitconfig-local
}

setup_local_files() {
	create_file "$HOME/.bash-local" <<- EOF
		EMAIL="$EMAIL"
		UNAME="$UNAME"
		GIT_REMOTE_IDENTITY='
		git@github.com:proj $EMAIL $UNAME
		'
		export EMAIL UNAME GIT_REMOTE_IDENTITY
	EOF

	SDKROOT=$(xcrun --sdk macosx --show-sdk-path 2> /dev/null)
	if test -n "$SDKROOT"; then
		echo "export SDKROOT=$SDKROOT" >> $HOME/.bash-local
	fi

	create_file "$HOME/.config/CONFIG_SITE" <<- 'EOF'
		if test "${prefix}" = NONE; then
			prefix="$HOME/$(uname -m)/$(uname -s)"
			CPPFLAGS="$CPPFLAGS -I${prefix}/include"
			LDFLAGS="$LDFLAGS -L${prefix}/lib"
			if test -n "$SDKROOT"; then
				CFLAGS="-isysroot $SDKROOT $CFLAGS"
				LDFLAGS="-Wl,-syslibroot,$SDKROOT $LDFLAGS"
			fi
		fi
	EOF

	create_file "$HOME/.config/meson.ini" <<- EOF
		[built-in options]
		prefix = '$HOME/$(uname -m)/$(uname -s)'
	EOF
}

main() {
	init "$@"
	create_symlinks
	setup_local_files

	ln -sf "$base/scripts" scripts
	mkdir -p "$HOME"/.config/bash
	(cd "$HOME"/.config/bash
	curl -s -O https://raw.githubusercontent.com/git/git/master/contrib/completion/git-completion.bash
	)

	git ciam 'Setup script modified dotfiles in $HOME'
}

main "$@"