#!/bin/sh

# mdview - simple markdown viewer
# Usage: mdview [--light|--dark|--auto] [--live] <file.md>

theme="auto"
live_mode=0
filename=""
# lang="en" - maybe support language tags later

for arg in "$@"; do
	case "$arg" in
		--light) theme="light" ;;
		--dark) theme="dark" ;;
		--auto) theme="auto" ;;
		--live|-w) live_mode=1 ;;
		--help|-h)
			echo "Usage: mdview [--light|--dark|--auto] [--live] <file.md>"
			echo "	--light   Light theme"
			echo "	--dark	  Dark theme"
			echo "	--auto	  Follow system (default)"
			echo "	--live	  Watch file for changes"
			exit 0
			;;
		*) filename="$arg" ;;
	esac
done

if [ -z "$filename" ]; then
	echo "Usage: mdview [--light|--dark|--auto] [--live] <file.md>" >&2
	exit 1
fi

# Resolve the base directory for relative paths
if [ "$filename" = "-" ]; then
    base_dir="file://$(pwd)/"
else
    base_dir="file://$(cd "$(dirname "$filename")" && pwd)/"
fi

case "$theme" in
	light)
		css_file="$HOME/.config/mdview/github-markdown-light.css"
		page_background="#ffffff"
		page_scheme="light"
		;;
	dark)
		css_file="$HOME/.config/mdview/github-markdown-dark.css"
		page_background="#0d1117"
		page_scheme="dark"
		;;
	auto)
		css_file="$HOME/.config/mdview/github-markdown.css"
		page_background="Canvas"
		page_scheme="light dark"
		;;
esac

html() {
	if [ "$filename" = "-" ]; then
		body=$(cat | cmark-gfm --width 80 --unsafe)
	else
		body=$(cmark-gfm --width 80 --unsafe "$filename")
	fi

	cat <<EOF
<!doctype html>
<html lang="en">
<head>
	<meta charset="utf-8">
	<meta name="viewport" content="width=device-width, initial-scale=1">
	<base href="$base_dir">
	<style>
	:root {
		color-scheme: $page_scheme;
	}

	html,
	body {
		min-height: 100%;
	}

	body {
		margin: 0;
		background-color: $page_background;
	}

	.markdown-body {
		box-sizing: border-box;
		min-width: 200px;
		max-width: 980px;
		min-height: 100vh;
		margin: 0 auto;
		padding: 45px;
	}

	@media (max-width: 767px) {
		.markdown-body {
			padding: 15px;
		}
	}
	</style>
</head>
<body>
	<article class="markdown-body">
$body
	</article>
</body>
</html>
EOF
}

if [ "$live_mode" -eq 1 ]; then
	if [ "$filename" = "-" ]; then
		echo "mdview: --live cannot be used with standard input" >&2
		exit 1
	fi

	tmp=$(mktemp /tmp/mdview_live_XXXXXX.html)
	surf_pid=""

	cleanup() {
		[ -n "$surf_pid" ] && kill "$surf_pid" 2>/dev/null
		rm -f "$tmp"
	}

	render() {
		html > "$tmp" || return 1

		if [ -n "$surf_pid" ]; then
			kill -HUP "$surf_pid" 2>/dev/null || return 1
		fi
	}

	trap cleanup EXIT INT TERM

	render || exit 1

	echo "Live preview: $filename (theme: $theme)"
	echo "Press Ctrl+C to stop"

	# -d disables surf's disk cache.
	surf -d -C "$css_file" "$tmp" &
	surf_pid=$!

	old_sum=$(cksum < "$filename") || exit 1

	while kill -0 "$surf_pid" 2>/dev/null; do
		sleep 1

		new_sum=$(cksum < "$filename") || continue
		[ "$new_sum" = "$old_sum" ] && continue

		old_sum=$new_sum

		if render; then
			echo "Updated: $filename"
		fi
	done
else
	tmp=$(mktemp /tmp/mdview_XXXXXX.html)
	html > "$tmp"
	surf -C "$css_file" "$tmp"
	rm -f "$tmp"
fi