#!/bin/sh

# Author:     Héctor Molinero Fernández <hector@molinero.dev>
# License:    MIT, https://opensource.org/licenses/MIT
# Repository: https://github.com/hectorm/hblock

set -eu
export LC_ALL='C'

# Check if a program exists.
exists() {
	# shellcheck disable=SC2230
	if command -v true; then command -v -- "${1:?}"
	elif eval type type; then eval type -- "${1:?}"
	else which -- "${1:?}"; fi >/dev/null 2>&1
}

# Check whether a string ends with the characters of a specified string.
endsWith() { [ "${1%"${2?}"}" != "${1?}" ]; }

# Base16 encode.
base16Encode() {
	if exists hexdump; then hexdump -ve '/1 "%02x"'
	elif exists od; then od -v -tx1 -An | tr -d '\n '
	else exit 1; fi
}

# Base64 encode.
base64Encode() {
	if exists base64; then base64 | tr -d '\r\n'
	elif exists uuencode; then uuencode -m - | sed '1d;$d' | tr -d '\r\n'
	else exit 1; fi
}

# Calculate a SHA256 checksum.
sha256Checksum() {
	if exists sha256sum; then sha256sum | cut -c 1-64
	elif exists sha256; then sha256 | cut -c 1-64
	elif exists shasum; then shasum -a 256 | cut -c 1-64
	elif exists openssl; then openssl sha256 -binary | base16Encode
	else exit 1; fi
}

# Escape string for use in HTML.
escapeHTML() {
	printf '%s' "${1?}" | awk -v RS='' "$(cat <<-'EOF'
		{
			gsub(/&/, "\\&#38;")
			gsub(/</, "\\&#60;")
			gsub(/>/, "\\&#62;")
			gsub(/"/, "\\&#34;")
			gsub(/'/, "\\&#39;")
			gsub(/\n/, "\\&#10;")
			printf("%s\n", $0)
		}
	EOF
	)"
}

# RFC 3986 compliant URL encoding method.
encodeURI() {
	_LC_COLLATE="${LC_COLLATE-}"; LC_COLLATE='C'
	hex="$(printf '%s' "${1?}" | base16Encode | sed 's|\(.\{2\}\)|\1 |g')"
	for h in ${hex?}; do
		case "${h:?}" in
			3[0-9]|\
			4[1-9a-f]|5[0-9a]|\
			6[1-9a-f]|7[0-9a]|\
			2d|5f|2e|7e\
			) printf '%b' '\0'"$(printf '%o' "0x${h:?}")" ;;
			*) printf '%%%s' "${h:?}"
		esac
	done
	LC_COLLATE="${_LC_COLLATE?}"
}

# Calculate digest for Content-Security-Policy.
cspDigest() {
	hex="$(printf '%s' "${1?}" | sha256Checksum | sed 's|\(.\{2\}\)|\1 |g')"
	b64="$(for h in ${hex?}; do printf '%b' '\0'"$(printf '%o' "0x${h:?}")"; done | base64Encode)"
	printf 'sha256-%s' "${b64?}"
}

# Get file size (or space if it is not a file).
getFileSize() {
	if [ -f "${1:?}" ]; then
		wc -c < "${1:?}" | awk '{printf("%0.2f kB",$1/1000)}'
	else
		printf ' '
	fi
}

# Get file MIME type.
getFileType() {
	if exists file; then
		file -bL --mime-type -- "${1:?}"
	else
		printf '%s' 'application/octet-stream'
	fi
}

# Get file modification time.
getFileModificationTime() {
	if stat -c '%n' -- "${1:?}" >/dev/null 2>&1; then
		TZ='UTC' stat -c '%.19y UTC' -- "${1:?}"
	elif stat -f '%Sm' -t '%Z' -- "${1:?}" >/dev/null 2>&1; then
		TZ='UTC' stat -f '%Sm' -t '%Y-%m-%d %H:%M:%S %Z' -- "${1:?}"
	else
		printf '%s' '1970-01-01 00:00:00 UTC'
	fi
}

main() {
	directory="${1:-./}"

	if [ ! -d "${directory:?}" ] || [ ! -r "${directory:?}" ]; then
		printf '%s\n' "Cannot read directory: '${directory:?}'" >&2
		exit 1
	fi

	entries="$(cd -- "${directory:?}" && for file in ./*; do
		if [ ! -r "${file:?}" ] || endsWith "${file:?}" 'index.html'; then
			continue
		fi

		fileName="$(basename "${file:?}")"
		escapedFileName="$(escapeHTML "${fileName:?}")"
		escapedFileNameURI="$(escapeHTML "$(encodeURI "${fileName:?}")")"

		fileSize="$(getFileSize "${file:?}")"
		escapedFileSize="$(escapeHTML "${fileSize:?}")"

		fileType="$(getFileType "${file:?}")"
		escapedFileType="$(escapeHTML "${fileType:?}")"

		fileDate="$(getFileModificationTime "${file:?}")"
		escapedFileDate="$(escapeHTML "${fileDate:?}")"

		printf '%s\n' "$(cat <<-EOF
			<a class="row" href="./${escapedFileNameURI:?}" title="${escapedFileName:?}">
				<div class="cell">${escapedFileName:?}</div>
				<div class="cell">${escapedFileSize:?}</div>
				<div class="cell">${escapedFileType:?}</div>
				<div class="cell">${escapedFileDate:?}</div>
			</a>
		EOF
		)"
	done)"

	# Generated with:
	#  $ { printf '%s' 'data:image/png;base64,'; base64 -w0 './resources/logo/bitmaps/logo-shield-transparent-h32.png'; } | fold -w 128
	favicon="$(tr -d '\n' <<-'EOF'
		data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAYAAABzenr0AAAACXBIWXMAAADsAAAA7AF5KHG9AAAAGXRFWHRTb2Z0d2FyZQB3d3cuaW5rc2
		NhcGUub3Jnm+48GgAAA/hJREFUWIW1l09oFHcUxz/vN2sjLbSQm11oal121wbEg1U8mUADQshBmvRQD7FF8FAopYeIvYgi5BAKJQml3UtOAQ1aBJHYU5OLBEVIoTRust
		qWJMZUMTQ0S3Rn5vUw2Z2Z3ZnsJtt+YeHNm/e+7/v7837zW2gCmkq1aCrV0gxHoplk17JGEXkN6G+GZ1dwstmvnUxGnUxGnWz2wm55ZDdJdjb7kahOAGbL5apIX+Lhwx
		//dwGaTh91RX4GXq96VTSqHTI/f78pAU42m0N1DZElVX1qqa5gzF84juWKdCIyCLwZw/c3cME4zjQiaoskxZikqL4DvA20WPn8Z8GE2k2o2gW8iyoCuCKgCsbUhEpvLy
		QS6NWrZddbwHeuZQFb66MaTHlczRHVBa9iRhfGoUPIpUuevbmJ3rzZSFap2lE7rAYFSHc3WBZYFjI4iAwNwf799dJquGtnQKRUnjbp60P6+2FtDRIJ3DNn4OXLclwwB+
		npQXp6YHkZVldR20ZaW9GxMfTGjcYFqGqpQm1ZkEqFCtVFMgnJJCGOMndDMxAMKo82CoUCOj7u6Uqn4ciRaIGvQjXrCzAim1reucVibH2dmPBtgMOHMVeuhGcMYGPD54
		aaEdVsQlV9WrFXV2MF1GB2FvfcOVhfD/MFOFR1pa4AVBcr9kpNfBh793q/MpaX0dHRcMyTJ74tskgVIk6XQNDz52DbkbXl+HHMzAxmZgY5dszXPz3tB5VK8OLFzgRoMM
		hxvLaKwokT/gx0dvr+Z898e2kJXNfndt2lugKsUumXkKAHD6IFBI/moB0sWJVriczWFSCPHi0Cv1cc93f0cQvj3r3g07zk80+qQ6KOYoCpsqF373pLsVPYtpdbhsh0VF
		jklUxhUuBTwDtW79xBuruRri5vYwG0tfkJbW3IyZOevWePxzE56W1in/OnqFqRZ6t2dCTclZUC4FU5eBBz/XroWN0WjoPb2wtzc2XPotm37z2ZmqppqcglkKkpGxG/oe
		fmavt7G+jISLA4iAxHFY8VAGBsOwf8WSHN5dDbt+sXv3ULzeWCrj+2uKLrxL2QQmHdwGnAU+446MAAeu1afPHxcfT8+WAr2kbkEykU1uNy6n5fnXT6K0S+CSWdOoVcvO
		gfw8Uievly9a1IgS+tfH54O/6GbsVOJvMF8G0o/sABzNAQuC7uwAA8Dl33XOBzK5//vh53w9dyO5M5LfAD8EbFmdjq4vD34h9VPZuYn49fq90IANBU6n3XmAlE2mNCfj
		Wu+7EsLMzFvK9B7CaMghQKv5li8QNUR9i6h5S1AcNmY+PoTorDLv+aAZTS6Q+NyBiQUNc9m1hYqN+j/zW0vb1V29tbm+H4F9A2hjZyunFYAAAAAElFTkSuQmCC
	EOF
	)"

	# Generated with:
	#  $ svgo --datauri=enc --output=- './resources/logo/vectors/logo-a.svg' | fold -w 128
	logo="$(tr -d '\n' <<-'EOF'
		data:image/svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3.org%2F2000%2Fsvg%22%20width%3D%221024%22%20height%3D%22320%22%20viewB
		ox%3D%220%200%204000%201250%22%3E%3Cg%20stroke%3D%22%23FD2727%22%20stroke-width%3D%22133.2%22%3E%3Cpath%20fill%3D%22%23FFF%22%20
		d%3D%22M542.134%20130.213c-133.2%20159.839-133.2%20186.479-399.597%20149.183%200%20623.37%20133.2%20676.65%20399.597%20863.128C8
		08.53%20956.046%20941.73%20902.766%20941.73%20279.396c-266.398%2037.296-266.398%2010.656-399.596-149.183z%22%2F%3E%3Cpath%20d%3D
		%22M414.263%20263.412v543.451-165.166a127.87%20127.87%200%2001255.742%200v165.166-165.166%22%20fill%3D%22none%22%2F%3E%3C%2Fg%3E
		%3Cpath%20stroke%3D%22%23FD2727%22%20stroke-width%3D%22155.2%22%20d%3D%22M1318.091%20314.897v609.697V730.6a152.424%20152.424%200
		%2001304.85%200v193.994V730.6%22%20fill%3D%22none%22%2F%3E%3Cpath%20fill%3D%22%23FD2727%22%20d%3D%22M3480.936%20924.594h147.125v
		-105.09l45.54-50.793%2087.574%20155.883h162.889l-164.64-255.718%20155.882-182.155h-162.889L3631.564%20639.1h-3.503V315.074h-147.
		125zm-216.009%2010.51c45.54%200%20101.587-12.261%20145.374-50.794l-57.799-98.084c-21.018%2015.764-45.539%2028.024-70.06%2028.024
		-47.29%200-84.071-42.036-84.071-108.593%200-66.556%2033.278-108.592%2089.326-108.592%2015.763%200%2029.775%205.254%2049.042%2021
		.018l70.06-96.332c-33.279-28.024-75.315-45.54-127.86-45.54-124.356%200-234.7%2084.072-234.7%20229.446s96.332%20229.446%20220.688
		%20229.446zm-494.4%200c112.096%200%20217.185-84.073%20217.185-229.447%200-145.374-105.09-229.445-217.185-229.445s-217.185%2084.0
		71-217.185%20229.445%20105.09%20229.446%20217.185%20229.446zm0-120.854c-45.539%200-63.054-42.036-63.054-108.593%200-66.556%2017.
		515-108.592%2063.054-108.592s63.054%2042.036%2063.054%20108.592c0%2066.557-17.515%20108.593-63.054%20108.593zm-321.249%20120.853
		c33.279%200%2057.8-5.254%2073.563-12.26l-17.515-110.344c-7.006%201.751-10.509%201.751-15.763%201.751-10.51%200-24.521-8.757-24.5
		21-38.533V315.074h-150.628v455.389c0%2098.083%2033.278%20164.64%20134.864%20164.64zm-657.973-10.509h222.44c122.604%200%20224.191
		-50.793%20224.191-168.143%200-75.314-43.787-117.35-98.084-133.114v-3.503c43.788-17.515%2071.812-73.563%2071.812-122.604%200-112.
		096-96.333-141.871-215.434-141.871h-204.925zm150.629-346.796v-106.84h50.793c49.042%200%2071.811%2014.011%2071.811%2049.041s-22.7
		7%2057.8-71.811%2057.8zm0%20231.198V688.142h61.302c59.55%200%2087.575%2015.764%2087.575%2057.8s-28.024%2063.054-87.575%2063.054z
		%22%2F%3E%3C%2Fsvg%3E
	EOF
	)"

	# JavaScript.
	javascript="$(tr -d '\n' <<-'EOF'
		(function(){
		/* This resource is used to check the status of hBlock */
		var c=document.getElementById('status').classList;
		var i=document.createElement('img');c.add('loading');
		i.src='https://hblock-check.molinero.dev/1.png?_='+Date.now();
		i.onload=function(){c.add('disabled');c.remove('loading');};
		i.onerror=function(){c.add('enabled');c.remove('loading');};
		})();
	EOF
	)"

	# CSS.
	css="$(tr -d '\n' <<-'EOF'
		html {
			font-family: '-apple-system', 'BlinkMacSystemFont', 'Segoe UI', 'Roboto', 'Helvetica Neue', 'Arial', 'Noto Sans', sans-serif;
			font-size: 16px;
			color: #424242;
			background-color: #FAFAFA;
		}

		a {
			color: #0D47A1;
			text-decoration: none;
		}

		a:hover,
		a:focus {
			text-decoration: underline;
		}

		.container {
			margin: 20px auto;
			width: 100%;
			max-width: 1000px;
		}

		.section {
			margin: 0 10px 10px;
		}

		.title {
			font-size: 22px;
			font-weight: 700;
		}

		.table {
			display: table;
			width: 100%;
			border-collapse: collapse;
			table-layout: fixed;
		}

		.row {
			display: table-row;
		}

		.row:not(:last-child) {
			border-bottom: 1px solid #E0E0E0;
		}

		.row:first-child {
			font-weight: 700;
		}

		a.row {
			color: inherit;
			text-decoration: none;
		}

		a.row:hover,
		a.row:focus {
			background-color: #F5F5F5;
		}

		.cell {
			display: table-cell;
			padding: 15px 10px;
			white-space: pre;
			overflow: hidden;
			text-overflow: ellipsis;
		}

		.cell:nth-child(1) { width: 35%; }
		.cell:nth-child(2) { width: 15%; }
		.cell:nth-child(3) { width: 20%; }
		.cell:nth-child(4) { width: 30%; }

		@media (max-width: 768px) {
			.table, .row, .cell {
				display: block;
			}

			.row {
				padding: 15px 10px;
			}

			.row:first-child {
				display: none;
			}

			.cell {
				padding: 0 0 5px;
				width: auto !important;
				white-space: normal;
			}

			.cell::before {
				display: inline-block;
				margin-right: 5px;
				font-weight: 700;
			}

			.cell:nth-child(1)::before {
				content: 'Filename:';
			}

			.cell:nth-child(2)::before {
				content: 'Size:';
			}

			.cell:nth-child(3)::before {
				content: 'Type:';
			}

			.cell:nth-child(4)::before {
				content: 'Modified:';
			}
		}

		#status::before {
			display: inline-block;
			content: '';
		}

		#status:not(.loading):before {
			content: 'It was not possible to determine if you are using hBlock.';
			color: #37474F;
		}

		#status.enabled::before {
			content: 'You are using hBlock.';
			color: #388E3C;
		}

		#status.disabled::before {
			content: 'You are currently not using hBlock.';
			color: #D32F2F;
		}
	EOF
	)"

	# HTML.
	printf '%s\n' "$(tr -d '\n' <<-EOF
		<!DOCTYPE html>
		<html lang="en">

		<head>
			<meta charset="utf-8">
			<meta name="viewport" content="width=device-width, initial-scale=1">

			<meta http-equiv="Content-Security-Policy" content="
				default-src 'none';
				 script-src '$(cspDigest "${javascript?}")';
				 style-src '$(cspDigest "${css?}")';
				 img-src 'self' data: https://hblock-check.molinero.dev/1.png;
				 connect-src 'self';
			">

			<title>Index of /hBlock</title>
			<meta name="description" content="Improve your security and privacy by blocking ads, tracking and malware domains">
			<meta name="author" content="H&#233;ctor Molinero Fern&#225;ndez <hector@molinero.dev>">
			<meta name="license" content="MIT, https://opensource.org/licenses/MIT">
			<link rel="canonical" href="https://hblock.molinero.dev/">

			<link rel="icon" type="image/png" href="${favicon?}">

			<!-- See: http://ogp.me -->
			<meta property="og:title" content="Index of /hBlock">
			<meta property="og:description" content="Improve your security and privacy by blocking ads, tracking and malware domains">
			<meta property="og:type" content="website">
			<meta property="og:url" content="https://hblock.molinero.dev/">
			<meta property="og:image" content="https://raw.githubusercontent.com/hectorm/hblock/master/resources/logo/bitmaps/logo-shield-ffffff-h512.png">

			<style>${css?}</style>
		</head>

		<body>
			<div class="container">
				<div class="section">
					<p>
						<a title="hBlock project page" href="https://github.com/hectorm/hblock">
							<img src="${logo?}" width="160" height="50" alt="hBlock">
						</a>
					</p>
					<p>
						hBlock is a POSIX-compliant shell script that gets a list of domains that serve ads, tracking scripts and malware from
						 <a title="Sources" href="https://github.com/hectorm/hblock/blob/master/SOURCES.md">multiple sources</a> and creates a
						 <a title="Hosts file definition" href="https://en.wikipedia.org/wiki/Hosts_(file)">hosts file</a>,
						 <a title="Alternative formats" href="https://github.com/hectorm/hblock/tree/master/resources/alt-formats/">among other formats</a>,
						 that prevents your system from connecting to them.
					</p>
					<p>
						On this website you can download the latest build of the default blocklist and you can generate your own by following the
						 instructions on the project page
						 (<a title="hBlock project page" href="https://github.com/hectorm/hblock">github.com/hectorm/hblock</a>).
					</p>
				</div>
				<div class="section">
					<h2 class="title">Status</h2>
					<span id="status"></span>
				</div>
				<div class="section">
					<h2 class="title">Latest build ($(date '+%Y-%m-%d'))</h2>
					<div class="table">
						<div class="row">
							<div class="cell">Filename</div>
							<div class="cell">Size</div>
							<div class="cell">Type</div>
							<div class="cell">Modified</div>
						</div>
						${entries?}
					</div>
				</div>
			</div>
			<script>${javascript?}</script>
		</body>

		</html>
	EOF
	)"
}

main "${@-}"