(function () {
    'use strict';

    var configurationElement = document.getElementById('analytics-configuration');
    var banner = document.getElementById('analytics-consent');
    var settingsButton = document.getElementById('analytics-consent-settings');

    if (!configurationElement || !banner || !settingsButton) {
        return;
    }

    var configuration;
    try {
        configuration = JSON.parse(configurationElement.textContent || '');
    } catch (error) {
        return;
    }

    var cookieName = configuration.consentCookie;
    var visitorCookieName = configuration.visitorCookie;
    var consentVersion = configuration.consentVersion;
    var pageViewSent = false;

    function readCookie(name) {
        var cookies = document.cookie ? document.cookie.split(';') : [];
        for (var index = 0; index < cookies.length; index += 1) {
            var parts = cookies[index].trim().split('=');
            var currentName = decodeURIComponent(parts.shift() || '');
            if (currentName === name) {
                return decodeURIComponent(parts.join('='));
            }
        }
        return null;
    }

    function readDecision() {
        var value = readCookie(cookieName);
        var expectedPrefix = consentVersion + ':';
        if (!value || value.indexOf(expectedPrefix) !== 0) {
            return null;
        }

        var decision = value.slice(expectedPrefix.length);
        return decision === 'granted' || decision === 'denied' ? decision : null;
    }

    function cookieSuffix() {
        var suffix = '; Path=/; Max-Age=' + String(configuration.consentMaxAge) + '; SameSite=Lax';
        if (configuration.cookieDomain) {
            suffix += '; Domain=' + configuration.cookieDomain;
        }
        if (configuration.secureCookies || window.location.protocol === 'https:') {
            suffix += '; Secure';
        }
        return suffix;
    }

    function writeCookie(name, value) {
        document.cookie = encodeURIComponent(name) + '=' + encodeURIComponent(value) + cookieSuffix();
    }

    function writeDecision(decision) {
        writeCookie(cookieName, consentVersion + ':' + decision);
    }

    function randomVisitorId() {
        var bytes = new Uint8Array(8);
        window.crypto.getRandomValues(bytes);
        return Array.prototype.map.call(bytes, function (value) {
            return value.toString(16).padStart(2, '0');
        }).join('');
    }

    function ensureVisitorId() {
        var visitorId = readCookie(visitorCookieName);
        if (!visitorId || !/^[0-9a-f]{16}$/.test(visitorId)) {
            visitorId = randomVisitorId();
            writeCookie(visitorCookieName, visitorId);
        }
        return visitorId;
    }

    function URLWithoutParameters(value) {
        try {
            var url = new URL(value, window.location.href);
            return url.origin + url.pathname;
        } catch (error) {
            return '';
        }
    }

    function sendPageView() {
        if (pageViewSent || readDecision() !== 'granted') {
            return;
        }
        pageViewSent = true;

        var now = new Date();
        var payload = {
            visitorId: ensureVisitorId(),
            pageUrl: URLWithoutParameters(window.location.href),
            pageTitle: document.title || 'Kaffeeliste',
            referrerUrl: URLWithoutParameters(document.referrer),
            resolution: window.screen && window.screen.width && window.screen.height
                ? String(window.screen.width) + 'x' + String(window.screen.height)
                : '',
            language: window.navigator.language || '',
            h: now.getHours(),
            m: now.getMinutes(),
            s: now.getSeconds()
        };

        window.fetch(configuration.trackingEndpoint, {
            method: 'POST',
            credentials: 'same-origin',
            headers: {'Content-Type': 'application/json'},
            body: JSON.stringify(payload),
            keepalive: true
        }).catch(function () {
            // Analysefehler duerfen die Website niemals beeintraechtigen.
        });
    }

    function expireCookie(name, domain) {
        var value = encodeURIComponent(name) + '=; Path=/; Max-Age=0; SameSite=Lax';
        if (domain) {
            value += '; Domain=' + domain;
        }
        if (configuration.secureCookies || window.location.protocol === 'https:') {
            value += '; Secure';
        }
        document.cookie = value;
    }

    function removeAnalysisCookies() {
        var cookies = document.cookie ? document.cookie.split(';') : [];
        cookies.forEach(function (cookie) {
            var name = decodeURIComponent(cookie.trim().split('=')[0] || '');
            if (name !== visitorCookieName && name.indexOf('_pk_') !== 0 && name.indexOf('mtm_') !== 0) {
                return;
            }
            expireCookie(name, '');
            if (configuration.cookieDomain) {
                expireCookie(name, configuration.cookieDomain);
            }
        });
    }

    function closeBanner() {
        banner.hidden = true;
        settingsButton.hidden = false;
    }

    function choose(decision) {
        writeDecision(decision);
        closeBanner();
        if (decision === 'granted') {
            sendPageView();
        } else {
            removeAnalysisCookies();
        }
        window.dispatchEvent(new CustomEvent('kaffeeliste:analytics-consent', {
            detail: {analytics: decision}
        }));
    }

    banner.querySelectorAll('[data-analytics-consent]').forEach(function (button) {
        button.addEventListener('click', function () {
            choose(button.getAttribute('data-analytics-consent'));
        });
    });

    settingsButton.addEventListener('click', function () {
        banner.hidden = false;
        settingsButton.hidden = true;
        var firstButton = banner.querySelector('[data-analytics-consent="denied"]');
        if (firstButton) {
            firstButton.focus();
        }
    });

    var initialDecision = readDecision();
    if (initialDecision === 'granted') {
        settingsButton.hidden = false;
        sendPageView();
    } else if (initialDecision === 'denied') {
        settingsButton.hidden = false;
        removeAnalysisCookies();
    } else {
        banner.hidden = false;
    }
}());