/* ==========================================================================
   MSOS Assistant — offline "find my answer" helper.
   100% in-browser: no API, no server, no cost. Lazy-loads a small per-language
   index and answers with a short snippet + a link to the full page.
   Dependency-free so it stays CSP-safe (script-src 'self').
   ========================================================================== */
(function () {
    "use strict";

    var LANG = (document.documentElement.lang || "en").toLowerCase();
    if (LANG === "sl") LANG = "si";            // site uses lang="sl", files use "si"
    if (["en", "mk", "si"].indexOf(LANG) < 0) LANG = "en";

    /* ---- localized UI strings ---- */
    var UI = {
        en: { title: "Ask MSOS", open: "Ask MSOS", placeholder: "Ask a question…",
              send: "Send", close: "Close",
              greeting: "Hi! 👋 Ask me anything about studying in Slovenia or MSOS and I'll point you to the right page.",
              found: "Here's what I found:", more: "Read more",
              none: "I couldn't find a clear answer. Try the Student Welcome Guide, or email info@msosorg.com.",
              guideUrl: "/en/student-welcome-guide/", disclaimer: "Answers come straight from this website." },
        mk: { title: "Прашај MSOS", open: "Прашај MSOS", placeholder: "Постави прашање…",
              send: "Испрати", close: "Затвори",
              greeting: "Здраво! 👋 Прашај ме било што за студирање во Словенија или за MSOS и ќе те упатам до вистинската страница.",
              found: "Еве што најдов:", more: "Прочитај повеќе",
              none: "Не најдов јасен одговор. Пробај го Водичот за студенти или пиши на info@msosorg.com.",
              guideUrl: "/mk/student-welcome-guide/", disclaimer: "Одговорите доаѓаат директно од оваа страница." },
        si: { title: "Vprašaj MSOS", open: "Vprašaj MSOS", placeholder: "Zastavi vprašanje…",
              send: "Pošlji", close: "Zapri",
              greeting: "Živjo! 👋 Vprašaj me karkoli o študiju v Sloveniji ali o MSOS in usmeril te bom na pravo stran.",
              found: "Tole sem našel:", more: "Preberi več",
              none: "Nisem našel jasnega odgovora. Poglej Vodnik za študente ali piši na info@msosorg.com.",
              guideUrl: "/si/student-welcome-guide/", disclaimer: "Odgovori prihajajo neposredno s te spletne strani." }
    }[LANG];

    /* ---- curated short answers for common questions (checked before search).
       EN is complete; MK/SI seed a few — machine-drafted, PROOFREAD before launch.
       Add more freely: {k:[keywords], a:"short answer", u:"/lang/page/"} ---- */
    var INTENTS = {
        en: [
            { k: ["residence", "permit", "temporary", "stay"], u: "/en/student-welcome-guide/student-residence-permit/",
              a: "You apply for a temporary residence permit for study (usually before or right after arrival). It takes several documents and steps and is valid ~1 year, then renewed." },
            { k: ["visa"], u: "/en/student-welcome-guide/student-residence-permit/",
              a: "Non-EU students generally need a residence permit for study rather than a short visa. See the residence-permit guide for the documents and steps." },
            { k: ["cost", "living", "expenses", "budget", "money", "rent"], u: "/en/get-to-know-slovenia/",
              a: "Monthly living costs depend on your city and housing. The guide breaks down rent, food, transport and student discounts." },
            { k: ["accommodation", "housing", "dorm", "apartment", "room", "student home"], u: "/en/student-welcome-guide/student-accommodation/",
              a: "You can look at student dorms and private rentals. The accommodation guide explains how and where to search." },
            { k: ["english", "slovene", "slovenian", "language"], u: "/en/student-welcome-guide/",
              a: "Some programmes are in English; many are in Slovene. Learning basic Slovene helps a lot with daily life and admin." },
            { k: ["work", "job", "part-time", "student work"], u: "/en/student-welcome-guide/",
              a: "Students can work part-time through student work ('študentsko delo'). The guide covers how it works alongside studies." },
            { k: ["boni", "benefits", "discount", "meal", "subsidised"], u: "/en/student-welcome-guide/",
              a: "Students get subsidised meals ('boni') and many discounts. See the guide for how to register and use them." },
            { k: ["tuition", "fees", "scholarship", "funding", "ad futura"], u: "/en/student-welcome-guide/application-deadlines/",
              a: "Tuition varies by programme and status; scholarships like Ad Futura exist. Check deadlines and funding in the guide." },
            { k: ["bank", "account", "iban"], u: "/en/blog/how-to-open-slovenian-bank-account/",
              a: "Opening a Slovenian bank account is straightforward with your documents. The blog post walks through it step by step." },
            { k: ["enrol", "enrolment", "evš", "evs", "apply", "application", "admission"], u: "/en/student-welcome-guide/evs-application-guide/",
              a: "You apply through the eVŠ portal. The eVŠ guide shows exactly how to submit your application." },
            { k: ["arrival", "checklist", "first", "when i arrive", "moving"], u: "/en/student-welcome-guide/arrival-checklist/",
              a: "There's a first-weeks arrival checklist (registration, permit, bank, health, etc.) to keep you on track." },
            { k: ["member", "join", "membership", "become"], u: "/en/become-a-member/",
              a: "You can join in a couple of minutes — students and supporters both welcome. Use the Become a member form." },
            { k: ["support", "donate", "donation", "sponsor", "help"], u: "/en/support/",
              a: "You can support MSOS by bank transfer, sponsorship or partnership. See the Support page for details." },
            { k: ["contact", "email", "reach", "get in touch"], u: "/en/legal/",
              a: "You can reach MSOS at info@msosorg.com. Official details are on the Official information page." }
        ],
        mk: [
            { k: ["дозвол", "престој", "виза"], u: "/mk/student-welcome-guide/student-residence-permit/",
              a: "Аплицираш за дозвола за привремен престој за студирање. Потребни се неколку документи и чекори; важи околу 1 година." },
            { k: ["член", "зачлен", "приклуч"], u: "/mk/become-a-member/",
              a: "Можеш да се зачлениш за неколку минути — добредојдени се и студенти и поддржувачи." },
            { k: ["поддрш", "донац", "донир"], u: "/mk/support/",
              a: "Можеш да го поддржиш MSOS преку банкарски трансфер, спонзорство или партнерство. Види ја страницата Поддршка." },
            { k: ["сместув", "стан", "дом"], u: "/mk/student-welcome-guide/student-accommodation/",
              a: "Можеш да бараш студентски домови или приватно сместување. Водичот објаснува како и каде." },
            { k: ["контакт", "е-пошта", "мејл"], u: "/mk/legal/",
              a: "Контактирај го MSOS на info@msosorg.com. Официјалните податоци се на страницата Официјални информации." }
        ],
        si: [
            { k: ["dovoljenje", "prebivanje", "vizum", "bivanje"], u: "/si/student-welcome-guide/student-residence-permit/",
              a: "Zaprosiš za dovoljenje za začasno prebivanje zaradi študija. Potrebnih je nekaj dokumentov in korakov; velja približno 1 leto." },
            { k: ["član", "včlan", "pridruž"], u: "/si/become-a-member/",
              a: "Včlaniš se lahko v nekaj minutah — dobrodošli so študenti in podporniki." },
            { k: ["podpri", "donacij", "donir"], u: "/si/support/",
              a: "MSOS lahko podpreš z bančnim nakazilom, sponzorstvom ali partnerstvom. Glej stran Podpri." },
            { k: ["nastanit", "stanovanje", "dom", "soba"], u: "/si/student-welcome-guide/student-accommodation/",
              a: "Iščeš lahko študentske domove ali zasebne najeme. Vodnik pojasni, kako in kje." },
            { k: ["kontakt", "e-pošta", "mail"], u: "/si/legal/",
              a: "MSOS dosežeš na info@msosorg.com. Uradni podatki so na strani Uradni podatki." }
        ]
    }[LANG] || [];

    /* ---- text normalization: lowercase + fold Latin diacritics (č→c…),
       keep Cyrillic. Tokenize on non-letter/digit (Unicode-aware). ---- */
    function norm(s) {
        s = (s || "").toLowerCase();
        try { s = s.normalize("NFD").replace(/[̀-ͯ]/g, ""); } catch (e) {}
        return s;
    }
    function tokens(s) {
        var out = [], m = norm(s).match(/[\p{L}\p{N}]+/gu);
        if (m) for (var i = 0; i < m.length; i++) if (m[i].length > 1) out.push(m[i]);
        return out;
    }
    // Question/filler words in EN + MK + SI; removed from queries so the
    // meaningful terms (e.g. "ohrid", "permit") drive the ranking.
    var STOP = (function () {
        var w = ("the a an of to in on for and or is are be was were do does did how what " +
            "when where why who which can could would should will my your our we they it this " +
            "that these those with at as by from about into over out up down me you i us them " +
            "have has had need want please get got give tell show find help hi hello hey thanks " +
            "kako kaj kje kdaj zakaj kdo kateri ali je so bo bi na za in ali da li mi me ti to ta " +
            "te tega se z s v iz pri od do imam imate zelim moram lahko prosim zivjo pozdravljeni " +
            "kako sto dali koi koga kade zosto koj koja e se na vo za i ili so da li mi me ti nie " +
            "toa ova imam sakam treba moze prosim zdravo ").split(/\s+/);
        var o = {}; for (var i = 0; i < w.length; i++) if (w[i]) o[w[i]] = 1; return o;
    })();

    /* ---- tiny BM25 search over the lazily-loaded index ---- */
    var INDEX = null, DF = null, AVGLEN = 0, ready = false, loading = false;

    function loadIndex() {
        if (ready || loading) return Promise.resolve();
        loading = true;
        return fetch("/assistant/index-" + LANG + ".json")
            .then(function (r) { return r.json(); })
            .then(function (data) {
                INDEX = data; DF = {}; var total = 0;
                for (var i = 0; i < INDEX.length; i++) {
                    var c = INDEX[i];
                    c._t = tokens(c.x + " " + c.h + " " + c.t);
                    c._len = c._t.length; total += c._len;
                    var seen = {};
                    for (var j = 0; j < c._t.length; j++) {
                        var w = c._t[j];
                        if (!seen[w]) { seen[w] = 1; DF[w] = (DF[w] || 0) + 1; }
                    }
                }
                AVGLEN = total / Math.max(INDEX.length, 1);
                ready = true; loading = false;
            })
            .catch(function () { loading = false; });
    }

    function search(query, k) {
        if (!ready) return [];
        var q0 = tokens(query); if (!q0.length) return [];
        var N = INDEX.length, k1 = 1.5, b = 0.75, scored = [];
        // Drop stopwords + very common terms so rare, meaningful words win.
        var q = q0.filter(function (t) { return !STOP[t] && (!DF[t] || DF[t] / N <= 0.4); });
        if (!q.length) q = q0.filter(function (t) { return !STOP[t]; });
        if (!q.length) q = q0;
        for (var i = 0; i < N; i++) {
            var c = INDEX[i], score = 0, tf = {};
            for (var j = 0; j < c._t.length; j++) tf[c._t[j]] = (tf[c._t[j]] || 0) + 1;
            for (var t = 0; t < q.length; t++) {
                var term = q[t], f = tf[term]; if (!f) continue;
                var idf = Math.log(1 + (N - DF[term] + 0.5) / (DF[term] + 0.5));
                score += idf * (f * (k1 + 1)) / (f + k1 * (1 - b + b * c._len / AVGLEN));
            }
            // boost when the query hits the heading/title
            var hn = norm(c.h + " " + c.t);
            for (var h = 0; h < q.length; h++) if (hn.indexOf(q[h]) >= 0) score += 0.6;
            if (score > 0) scored.push([score, c]);
        }
        scored.sort(function (a, b) { return b[0] - a[0]; });
        return scored.slice(0, k || 3).map(function (s) { return s[1]; });
    }

    function matchIntent(query) {
        var q = norm(query), best = null, bestHits = 0;
        for (var i = 0; i < INTENTS.length; i++) {
            var hits = 0;
            for (var j = 0; j < INTENTS[i].k.length; j++)
                if (q.indexOf(norm(INTENTS[i].k[j])) >= 0) hits++;
            if (hits > bestHits) { bestHits = hits; best = INTENTS[i]; }
        }
        return bestHits > 0 ? best : null;
    }

    /* ---- snippet: ~180 chars of a chunk, trimmed to a sentence ---- */
    function snippet(c) {
        var x = c.x;
        var lead = c.h && x.indexOf(c.h) === 0 ? x.slice(c.h.length).replace(/^[.\s]+/, "") : x;
        if (lead.length > 200) lead = lead.slice(0, 200).replace(/\s+\S*$/, "") + "…";
        return lead;
    }

    /* ========================= UI ========================= */
    var esc = function (s) { return String(s == null ? "" : s)
        .replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;")
        .replace(/"/g, "&quot;").replace(/'/g, "&#39;"); };

    var root, panel, log, input, launch, opened = false;

    function bubble(text, who, extraHTML) {
        var b = document.createElement("div");
        b.className = "msa-msg msa-" + who;
        b.innerHTML = '<div class="msa-bubble">' + text + (extraHTML || "") + "</div>";
        log.appendChild(b);
        log.scrollTop = log.scrollHeight;
        return b;
    }

    function answer(query) {
        bubble(esc(query), "user");
        var typing = bubble("…", "bot");
        Promise.resolve(ready ? null : loadIndex()).then(function () {
            typing.remove();
            var intent = matchIntent(query);
            var hits = search(query, 3);
            if (intent) {
                var extra = '<a class="msa-link" href="' + esc(intent.u) + '">' + esc(UI.more) + ' →</a>';
                bubble(esc(intent.a), "bot", extra);
                // offer one more related page from search if different
                var extraHit = hits.filter(function (c) { return c.u !== intent.u; })[0];
                if (extraHit) bubble('<span class="msa-also">' + esc(UI.found) + '</span> ' +
                    esc(extraHit.h) + ' <a class="msa-link" href="' + esc(extraHit.u) + '">' + esc(UI.more) + ' →</a>', "bot");
                return;
            }
            if (hits.length) {
                bubble('<span class="msa-also">' + esc(UI.found) + '</span>', "bot");
                hits.forEach(function (c) {
                    bubble('<strong>' + esc(c.h) + '</strong><br>' + esc(snippet(c)) +
                        '<br><a class="msa-link" href="' + esc(c.u) + '">' + esc(UI.more) + ' →</a>', "bot");
                });
            } else {
                bubble(esc(UI.none) + ' <a class="msa-link" href="' + esc(UI.guideUrl) + '">' + esc(UI.more) + ' →</a>', "bot");
            }
        });
    }

    function open() {
        opened = true; root.classList.add("msa-open");
        panel.setAttribute("aria-hidden", "false");
        launch.setAttribute("aria-expanded", "true");
        loadIndex();
        if (!log.childNodes.length) bubble(esc(UI.greeting), "bot");
        setTimeout(function () { input.focus(); }, 50);
    }
    function close() {
        opened = false; root.classList.remove("msa-open");
        panel.setAttribute("aria-hidden", "true");
        launch.setAttribute("aria-expanded", "false");
        launch.focus();
    }
    function submit() {
        var q = input.value.trim(); if (!q) return;
        input.value = ""; answer(q);
    }

    function build() {
        root = document.createElement("div");
        root.className = "msa-root"; root.setAttribute("data-msa", "1");
        root.innerHTML =
            '<button class="msa-launch" aria-expanded="false" aria-controls="msa-panel" aria-label="' + esc(UI.open) + '">' +
                '<i class="fas fa-comment-dots" aria-hidden="true"></i><span>' + esc(UI.open) + '</span></button>' +
            '<section class="msa-panel" id="msa-panel" role="dialog" aria-label="' + esc(UI.title) + '" aria-hidden="true">' +
                '<header class="msa-head"><span>' + esc(UI.title) + '</span>' +
                    '<button class="msa-x" aria-label="' + esc(UI.close) + '">&times;</button></header>' +
                '<div class="msa-log" role="log" aria-live="polite"></div>' +
                '<form class="msa-form"><input class="msa-input" type="text" autocomplete="off" ' +
                    'placeholder="' + esc(UI.placeholder) + '" aria-label="' + esc(UI.placeholder) + '">' +
                    '<button class="msa-send" type="submit" aria-label="' + esc(UI.send) + '"><i class="fas fa-paper-plane" aria-hidden="true"></i></button>' +
                '</form>' +
                '<p class="msa-foot">' + esc(UI.disclaimer) + '</p>' +
            '</section>';
        document.body.appendChild(root);
        panel = root.querySelector(".msa-panel");
        log = root.querySelector(".msa-log");
        input = root.querySelector(".msa-input");
        launch = root.querySelector(".msa-launch");
        launch.addEventListener("click", function () { opened ? close() : open(); });
        root.querySelector(".msa-x").addEventListener("click", close);
        root.querySelector(".msa-form").addEventListener("submit", function (e) { e.preventDefault(); submit(); });
        document.addEventListener("keydown", function (e) { if (e.key === "Escape" && opened) close(); });
    }

    if (document.readyState !== "loading") build();
    else document.addEventListener("DOMContentLoaded", build);
})();