Self-host GoatCounter JS, add link to results

4 files changed, 277 insertions, 3 deletions

diff --git a/source/_includes/footer.html b/source/_includes/footer.html
index 8a11b00..d91d3d5 100644
--- a/source/_includes/footer.html
+++ b/source/_includes/footer.html
@@ -4,5 +4,5 @@
 <a href="https://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA 4.0</a>.
 </div>
 <div class="footr noha">
-Privacy-friendly statistics by <a href="https://www.goatcounter.com/">GoatCounter</a>.
+<a href="https://prefetch.goatcounter.com/">Visitor statistics</a>
 </div>
diff --git a/source/_includes/preamble.html b/source/_includes/preamble.html
index 96b26b5..df39a13 100644
--- a/source/_includes/preamble.html
+++ b/source/_includes/preamble.html
@@ -19,4 +19,6 @@
 {% endif %}
 <link rel="stylesheet" href="/infra/css/main.css?v=20221027">
 
-<script data-goatcounter="https://prefetch.goatcounter.com/count" async src="https://gc.zgo.at/count.js"></script>
+{% if jekyll.environment != "development" %}
+<script data-goatcounter="https://prefetch.goatcounter.com/count" async src="/infra/js/count.js"></script>
+{% endif %}
diff --git a/source/index.md b/source/index.md
index 7847d5f..e40950b 100644
--- a/source/index.md
+++ b/source/index.md
@@ -22,5 +22,8 @@ where I explain STEM concepts I've learned over the years.
 
 This website is made by me using [Hugo](https://gohugo.io),
 and served to you by [nginx](https://nginx.org/).
-I intend to keep it free of advertising,
+I intend to keep it free of advertising and associated tracking,
 and to maintain my A+ score for [TLS quality](https://www.ssllabs.com/ssltest/analyze.html?d=prefetch.eu).
+Note that I do use [GoatCounter](https://www.goatcounter.com/)
+to collect some privacy-friendly statistics,
+which you can see [here](https://prefetch.goatcounter.com/).
diff --git a/source/infra/js/count.js b/source/infra/js/count.js
new file mode 100644
index 0000000..e7911ec
--- /dev/null
+++ b/source/infra/js/count.js
@@ -0,0 +1,269 @@
+// GoatCounter: https://www.goatcounter.com
+// This file (and *only* this file) is released under the ISC license:
+// https://opensource.org/licenses/ISC
+;(function() {
+	'use strict';
+
+	if (window.goatcounter && window.goatcounter.vars)  // Compatibility with very old version; do not use.
+		window.goatcounter = window.goatcounter.vars
+	else
+		window.goatcounter = window.goatcounter || {}
+
+	// Load settings from data-goatcounter-settings.
+	var s = document.querySelector('script[data-goatcounter]')
+	if (s && s.dataset.goatcounterSettings) {
+		try         { var set = JSON.parse(s.dataset.goatcounterSettings) }
+		catch (err) { console.error('invalid JSON in data-goatcounter-settings: ' + err) }
+		for (var k in set)
+			if (['no_onload', 'no_events', 'allow_local', 'allow_frame', 'path', 'title', 'referrer', 'event'].indexOf(k) > -1)
+				window.goatcounter[k] = set[k]
+	}
+
+	var enc = encodeURIComponent
+
+	// Get all data we're going to send off to the counter endpoint.
+	var get_data = function(vars) {
+		var data = {
+			p: (vars.path     === undefined ? goatcounter.path     : vars.path),
+			r: (vars.referrer === undefined ? goatcounter.referrer : vars.referrer),
+			t: (vars.title    === undefined ? goatcounter.title    : vars.title),
+			e: !!(vars.event || goatcounter.event),
+			s: [window.screen.width, window.screen.height, (window.devicePixelRatio || 1)],
+			b: is_bot(),
+			q: location.search,
+		}
+
+		var rcb, pcb, tcb  // Save callbacks to apply later.
+		if (typeof(data.r) === 'function') rcb = data.r
+		if (typeof(data.t) === 'function') tcb = data.t
+		if (typeof(data.p) === 'function') pcb = data.p
+
+		if (is_empty(data.r)) data.r = document.referrer
+		if (is_empty(data.t)) data.t = document.title
+		if (is_empty(data.p)) data.p = get_path()
+
+		if (rcb) data.r = rcb(data.r)
+		if (tcb) data.t = tcb(data.t)
+		if (pcb) data.p = pcb(data.p)
+		return data
+	}
+
+	// Check if a value is "empty" for the purpose of get_data().
+	var is_empty = function(v) { return v === null || v === undefined || typeof(v) === 'function' }
+
+	// See if this looks like a bot; there is some additional filtering on the
+	// backend, but these properties can't be fetched from there.
+	var is_bot = function() {
+		// Headless browsers are probably a bot.
+		var w = window, d = document
+		if (w.callPhantom || w._phantom || w.phantom)
+			return 150
+		if (w.__nightmare)
+			return 151
+		if (d.__selenium_unwrapped || d.__webdriver_evaluate || d.__driver_evaluate)
+			return 152
+		if (navigator.webdriver)
+			return 153
+		return 0
+	}
+
+	// Object to urlencoded string, starting with a ?.
+	var urlencode = function(obj) {
+		var p = []
+		for (var k in obj)
+			if (obj[k] !== '' && obj[k] !== null && obj[k] !== undefined && obj[k] !== false)
+				p.push(enc(k) + '=' + enc(obj[k]))
+		return '?' + p.join('&')
+	}
+
+	// Show a warning in the console.
+	var warn = function(msg) {
+		if (console && 'warn' in console)
+			console.warn('goatcounter: ' + msg)
+	}
+
+	// Get the endpoint to send requests to.
+	var get_endpoint = function() {
+		var s = document.querySelector('script[data-goatcounter]')
+		if (s && s.dataset.goatcounter)
+			return s.dataset.goatcounter
+		return (goatcounter.endpoint || window.counter)  // counter is for compat; don't use.
+	}
+
+	// Get current path.
+	var get_path = function() {
+		var loc = location,
+			c = document.querySelector('link[rel="canonical"][href]')
+		if (c) {  // May be relative or point to different domain.
+			var a = document.createElement('a')
+			a.href = c.href
+			if (a.hostname.replace(/^www\./, '') === location.hostname.replace(/^www\./, ''))
+				loc = a
+		}
+		return (loc.pathname + loc.search) || '/'
+	}
+
+	// Run function after DOM is loaded.
+	var on_load = function(f) {
+		if (document.body === null)
+			document.addEventListener('DOMContentLoaded', function() { f() }, false)
+		else
+			f()
+	}
+
+	// Filter some requests that we (probably) don't want to count.
+	goatcounter.filter = function() {
+		if ('visibilityState' in document && document.visibilityState === 'prerender')
+			return 'visibilityState'
+		if (!goatcounter.allow_frame && location !== parent.location)
+			return 'frame'
+		if (!goatcounter.allow_local && location.hostname.match(/(localhost$|^127\.|^10\.|^172\.(1[6-9]|2[0-9]|3[0-1])\.|^192\.168\.|^0\.0\.0\.0$)/))
+			return 'localhost'
+		if (!goatcounter.allow_local && location.protocol === 'file:')
+			return 'localfile'
+		if (localStorage && localStorage.getItem('skipgc') === 't')
+			return 'disabled with #toggle-goatcounter'
+		return false
+	}
+
+	// Get URL to send to GoatCounter.
+	window.goatcounter.url = function(vars) {
+		var data = get_data(vars || {})
+		if (data.p === null)  // null from user callback.
+			return
+		data.rnd = Math.random().toString(36).substr(2, 5)  // Browsers don't always listen to Cache-Control.
+
+		var endpoint = get_endpoint()
+		if (!endpoint)
+			return warn('no endpoint found')
+
+		return endpoint + urlencode(data)
+	}
+
+	// Count a hit.
+	window.goatcounter.count = function(vars) {
+		var f = goatcounter.filter()
+		if (f)
+			return warn('not counting because of: ' + f)
+
+		var url = goatcounter.url(vars)
+		if (!url)
+			return warn('not counting because path callback returned null')
+
+		var img = document.createElement('img')
+		img.src = url
+		img.style.position = 'absolute'  // Affect layout less.
+		img.style.bottom = '0px'
+		img.style.width = '1px'
+		img.style.height = '1px'
+		img.loading = 'eager'
+		img.setAttribute('alt', '')
+		img.setAttribute('aria-hidden', 'true')
+
+		var rm = function() { if (img && img.parentNode) img.parentNode.removeChild(img) }
+		img.addEventListener('load', rm, false)
+		document.body.appendChild(img)
+	}
+
+	// Get a query parameter.
+	window.goatcounter.get_query = function(name) {
+		var s = location.search.substr(1).split('&')
+		for (var i = 0; i < s.length; i++)
+			if (s[i].toLowerCase().indexOf(name.toLowerCase() + '=') === 0)
+				return s[i].substr(name.length + 1)
+	}
+
+	// Track click events.
+	window.goatcounter.bind_events = function() {
+		if (!document.querySelectorAll)  // Just in case someone uses an ancient browser.
+			return
+
+		var send = function(elem) {
+			return function() {
+				goatcounter.count({
+					event:    true,
+					path:     (elem.dataset.goatcounterClick || elem.name || elem.id || ''),
+					title:    (elem.dataset.goatcounterTitle || elem.title || (elem.innerHTML || '').substr(0, 200) || ''),
+					referrer: (elem.dataset.goatcounterReferrer || elem.dataset.goatcounterReferral || ''),
+				})
+			}
+		}
+
+		Array.prototype.slice.call(document.querySelectorAll("*[data-goatcounter-click]")).forEach(function(elem) {
+			if (elem.dataset.goatcounterBound)
+				return
+			var f = send(elem)
+			elem.addEventListener('click', f, false)
+			elem.addEventListener('auxclick', f, false)  // Middle click.
+			elem.dataset.goatcounterBound = 'true'
+		})
+	}
+
+	// Add a "visitor counter" frame or image.
+	window.goatcounter.visit_count = function(opt) {
+		on_load(function() {
+			opt        = opt        || {}
+			opt.type   = opt.type   || 'html'
+			opt.append = opt.append || 'body'
+			opt.path   = opt.path   || get_path()
+			opt.attr   = opt.attr   || {width: '200', height: (opt.no_branding ? '60' : '80')}
+
+			opt.attr['src'] = get_endpoint() + 'er/' + enc(opt.path) + '.' + enc(opt.type) + '?'
+			if (opt.no_branding) opt.attr['src'] += '&no_branding=1'
+			if (opt.style)       opt.attr['src'] += '&style=' + enc(opt.style)
+			if (opt.start)       opt.attr['src'] += '&start=' + enc(opt.start)
+			if (opt.end)         opt.attr['src'] += '&end='   + enc(opt.end)
+
+			var tag = {png: 'img', svg: 'img', html: 'iframe'}[opt.type]
+			if (!tag)
+				return warn('visit_count: unknown type: ' + opt.type)
+
+			if (opt.type === 'html') {
+				opt.attr['frameborder'] = '0'
+				opt.attr['scrolling']   = 'no'
+			}
+
+			var d = document.createElement(tag)
+			for (var k in opt.attr)
+				d.setAttribute(k, opt.attr[k])
+
+			var p = document.querySelector(opt.append)
+			if (!p)
+				return warn('visit_count: append not found: ' + opt.append)
+			p.appendChild(d)
+		})
+	}
+
+	// Make it easy to skip your own views.
+	if (location.hash === '#toggle-goatcounter') {
+		if (localStorage.getItem('skipgc') === 't') {
+			localStorage.removeItem('skipgc', 't')
+			alert('GoatCounter tracking is now ENABLED in this browser.')
+		}
+		else {
+			localStorage.setItem('skipgc', 't')
+			alert('GoatCounter tracking is now DISABLED in this browser until ' + location + ' is loaded again.')
+		}
+	}
+
+	if (!goatcounter.no_onload)
+		on_load(function() {
+			// 1. Page is visible, count request.
+			// 2. Page is not yet visible; wait until it switches to 'visible' and count.
+			// See #487
+			if (!('visibilityState' in document) || document.visibilityState === 'visible')
+				goatcounter.count()
+			else {
+				var f = function(e) {
+					if (document.visibilityState !== 'visible')
+						return
+					document.removeEventListener('visibilitychange', f)
+					goatcounter.count()
+				}
+				document.addEventListener('visibilitychange', f)
+			}
+
+			if (!goatcounter.no_events)
+				goatcounter.bind_events()
+		})
+})();