/**
 * assets/js/presenter.js  (v11)
 *
 * Controls slide navigation and DOM updates for the presentation view.
 * Depends on:
 *   - SLIDES      (global, JSON array from PHP)
 *   - SESSION_ID  (global, integer session ID)
 *   - BACK_URL    (global, URL to return to on exit)
 *   - RosaryRing  (global, from rosary.js)
 */

(function () {
    'use strict';

    if (!window.SLIDES || !SLIDES.length) {
        console.error('No slides data found.');
        return;
    }

    var currentIndex = 0;

    // -----------------------------------------------------------------------
    // Slide expansion — pre-split long prayers into "Part 1 / 2" / "Part 2 / 2"
    // so text stays large and readable on Zoom / projector rather than shrinking
    // to illegibility. Prayers with more than SPLIT_THRESHOLD combined lines are
    // automatically split at the nearest paragraph break.
    // -----------------------------------------------------------------------
    var SPLIT_THRESHOLD = 10;

    function countLines(text) {
        if (!text || !text.trim()) return 0;
        return text.split('\n').length;
    }

    function splitText(text) {
        // Prefer splitting at paragraph breaks (\n\n)
        var paras = text.split('\n\n');
        if (paras.length >= 2) {
            var mid = Math.ceil(paras.length / 2);
            var p1  = paras.slice(0, mid).join('\n\n').trim();
            var p2  = paras.slice(mid).join('\n\n').trim();
            if (p1 && p2) return [p1, p2];
        }
        // Fall back: split at line midpoint
        var lines = text.split('\n');
        var mid   = Math.ceil(lines.length / 2);
        return [lines.slice(0, mid).join('\n').trim(), lines.slice(mid).join('\n').trim()];
    }

    function expandSlides(rawSlides) {
        var result = [];
        for (var i = 0; i < rawSlides.length; i++) {
            var s           = rawSlides[i];
            var leaderLines = countLines(s.leader);
            var allLines    = countLines(s.all);
            if (leaderLines + allLines <= SPLIT_THRESHOLD) {
                result.push(s);
                continue;
            }
            // Decide which field to split (the longer one)
            var field  = (allLines >= leaderLines) ? 'all' : 'leader';
            var halves = splitText(s[field]);
            if (!halves[0] || !halves[1]) { result.push(s); continue; } // safety

            var p1 = Object.assign({}, s);
            var p2 = Object.assign({}, s);
            p1._partNum = 1;  p1._partTotal = 2;
            p2._partNum = 2;  p2._partTotal = 2;
            p2.bead_index = null; // bead was "prayed" in part 1

            if (field === 'all') {
                p1.all    = halves[0];
                p2.leader = '';
                p2.all    = halves[1];
            } else {
                p1.leader = halves[0];
                p1.all    = '';
                p2.leader = halves[1];
            }
            result.push(p1, p2);
        }
        return result;
    }

    var slides = expandSlides(SLIDES);
    var total  = slides.length;

    // localStorage key for resume position
    var RESUME_KEY = 'rosary_pos_' + (window.SESSION_ID || '0');

    // Pre-compute repeat-run info for every (possibly expanded) slide.
    // Group consecutive slides by prayer content (leader + all text), not title —
    // so opening Hail Marys "in Faith / Hope / Charity" and decade Hail Marys all
    // detect as runs even though their titles differ.
    var slideRunInfo = (function () {
        var info = new Array(total).fill(null);
        var i = 0;
        while (i < total) {
            var s   = slides[i];
            var key = s.type + '||' + (s.leader || '') + '||' + (s.all || '');
            var start = i;
            while (i < total) {
                var si = slides[i];
                var ki = si.type + '||' + (si.leader || '') + '||' + (si.all || '');
                if (ki !== key) break;
                i++;
            }
            var len = i - start;
            if (len > 1) {
                for (var j = start; j < i; j++) {
                    info[j] = { pos: j - start + 1, total: len };
                }
            }
        }
        return info;
    })();

    // Map bead index → first slide index that uses that bead.
    // Used by bead click navigation so clicking a bead jumps to the right slide.
    var beadToSlide = {};
    (function () {
        for (var i = 0; i < total; i++) {
            var bi = slides[i].bead_index;
            if (bi !== null && bi !== undefined && !(bi in beadToSlide)) {
                beadToSlide[bi] = i;
            }
        }
    })();

    // Scan slides 0..upToIndex and return the highest non-null bead_index seen.
    // Used so "between-bead" slides (Glory Be, Fatima, litanies) keep prayed
    // beads red instead of resetting everything to gray.
    function getLastPrayedBead(upToIndex) {
        var last = null;
        for (var i = 0; i <= upToIndex; i++) {
            var bi = slides[i] ? slides[i].bead_index : null;
            if (bi !== null && bi !== undefined) {
                last = bi;
            }
        }
        return last;
    }

    // DOM refs
    var coverSlide     = document.getElementById('cover-slide');
    var prayerSlide    = document.getElementById('prayer-slide');
    var mysterySlide   = document.getElementById('mystery-slide');
    var litanySlide    = document.getElementById('litany-slide');
    var closingSlide   = document.getElementById('closing-slide');

    var btnPrev        = document.getElementById('btn-prev');
    var btnNext        = document.getElementById('btn-next');
    var btnExit        = document.getElementById('btn-exit');
    var btnAudio       = document.getElementById('btn-audio');
    var slideCounter   = document.getElementById('slide-counter');
    var resumeToast    = document.getElementById('resume-toast');

    // --------------------------------------------------------------------------
    // Audio
    // AUDIO_MANIFEST: {key: ext, ...} — provided by present.php
    // AUDIO_BASE_URL: '/uploads/audio/'
    // --------------------------------------------------------------------------
    var AUDIO_PREF_KEY = 'rosary_audio'; // localStorage — global pref, not per-session
    var audioEnabled   = false;
    var currentAudio   = null;

    var hasAudioFiles = window.AUDIO_MANIFEST && Object.keys(AUDIO_MANIFEST).length > 0;

    if (hasAudioFiles) {
        var stored = localStorage.getItem(AUDIO_PREF_KEY);
        // Default ON when audio is available; user can mute
        audioEnabled = (stored === null) ? true : (stored === 'on');
    }

    function updateAudioBtn() {
        if (!btnAudio) return;
        if (audioEnabled) {
            btnAudio.innerHTML = '&#128264;'; // 🔊
            btnAudio.title     = 'Audio on — click to mute';
        } else {
            btnAudio.innerHTML = '&#128263;'; // 🔇
            btnAudio.title     = 'Audio off — click to enable';
        }
    }

    function stopAudio() {
        if (currentAudio) {
            currentAudio.pause();
            currentAudio.currentTime = 0;
            currentAudio = null;
        }
    }

    // Map a slide's id to a canonical audio key.
    // Many slides share one recording (e.g. all 55 Hail Marys → 'hail_mary').
    function getAudioKey(slide) {
        if (!slide) return null;
        var id = slide.id || '';
        if (!id || id === 'cover') return null;

        // Common prayers — many slides → one key
        if (id === 'sign_of_cross' || id === 'dm_sign_of_cross')  return 'sign_of_cross';
        if (id === 'apostles_creed' || id === 'dm_apostles_creed') return 'apostles_creed';
        if (id.indexOf('our_father') === 0 || id === 'dm_our_father_opening') return 'our_father';
        if (id.indexOf('hail_mary') === 0  || id === 'dm_hail_mary_opening')  return 'hail_mary';
        if (id.indexOf('glory_be') === 0)   return 'glory_be';
        if (id.indexOf('fatima_') === 0)    return 'fatima_prayer';

        // Mysteries — unique per mystery
        if (id.indexOf('mystery_') === 0)   return id;

        // Hail Holy Queen — both slides share one audio
        if (id.indexOf('hail_holy_queen') === 0) return 'hail_holy_queen';

        // Rosary closing prayer + generic closing
        if (id === 'rosary_closing_prayer') return 'rosary_closing_prayer';
        if (id === 'closing')               return 'closing';

        // Litany of Passion — unique per entry
        if (id.indexOf('litany_passion_') === 0) return id;

        // Novena deceased day prayers — unique per day
        if (id.indexOf('novena_day_') === 0) return id;

        // Litany for Departed — unique per entry
        if (id.indexOf('litany_departed_') === 0) return id;

        // Divine Mercy
        if (id === 'dm_opening')                    return 'dm_opening';
        if (id.indexOf('dm_blood_water') === 0)     return 'dm_blood_water';
        if (id.indexOf('dm_intention_day_') === 0)  return id;
        if (id.indexOf('dm_prayer_day_') === 0)     return id;
        if (id.indexOf('dm_eternal_father') === 0)  return 'dm_eternal_father';
        if (id.indexOf('dm_for_sake') === 0)        return 'dm_for_sake';
        if (id.indexOf('dm_holy_god') === 0)        return 'dm_holy_god';

        return id; // fallback: use slide ID directly
    }

    function playSlideAudio(slide) {
        stopAudio();
        if (!audioEnabled || !hasAudioFiles) return;
        var key = getAudioKey(slide);
        if (!key || !AUDIO_MANIFEST[key]) return;
        var audio = new Audio(window.AUDIO_BASE_URL + key + '.' + AUDIO_MANIFEST[key]);
        audio.play().catch(function () { /* silently skip — file may be absent */ });
        currentAudio = audio;
    }

    if (btnAudio) {
        btnAudio.addEventListener('click', function () {
            audioEnabled = !audioEnabled;
            try { localStorage.setItem(AUDIO_PREF_KEY, audioEnabled ? 'on' : 'off'); } catch (e) {}
            updateAudioBtn();
            if (!audioEnabled) stopAudio();
        });
    }

    updateAudioBtn();

    // Hide all slide panels
    function hideAll() {
        coverSlide.style.display   = 'none';
        prayerSlide.style.display  = 'none';
        mysterySlide.style.display = 'none';
        litanySlide.style.display  = 'none';
        closingSlide.style.display = 'none';
    }

    // Helpers
    function setText(id, value) {
        var el = document.getElementById(id);
        if (el) el.textContent = value || '';
    }
    function setHTML(id, value) {
        var el = document.getElementById(id);
        if (el) el.innerHTML = value || '';
    }
    function showEl(id) {
        var el = document.getElementById(id);
        if (el) el.style.display = '';
    }
    function hideEl(id) {
        var el = document.getElementById(id);
        if (el) el.style.display = 'none';
    }

    // Convert newlines to <br> for display, keeping pre-line behavior
    function nl(text) {
        if (!text) return '';
        return text.replace(/\n/g, '\n'); // already handled by white-space: pre-line
    }

    // --------------------------------------------------------------------------
    // Render a slide
    // --------------------------------------------------------------------------
    function render(index) {
        hideAll();
        var slide = slides[index];
        if (!slide) return;

        // Trigger CSS fade-in by re-inserting / touching the element
        switch (slide.type) {

            case 'cover':
                renderCover(slide);
                coverSlide.style.display = '';
                break;

            case 'mystery':
                renderMystery(slide);
                mysterySlide.style.display = '';
                break;

            case 'litany':
                renderLitany(slide);
                litanySlide.style.display = '';
                break;

            case 'closing':
                renderClosing(slide);
                closingSlide.style.display = '';
                break;

            default: // 'prayer'
                renderPrayer(slide);
                prayerSlide.style.display = '';
                break;
        }

        // Update counter (cover is slide 0, not counted in "Prayer X of Y")
        updateCounter(index);

        // Show repeat badge when the same content repeats (e.g. Agnus Dei × 3)
        updateRepeatBadge(index);

        // Shrink text so the slide fits on screen without scrolling
        fitTextToScreen();

        // Update rosary bead ring — pass both the current bead and the last prayed bead
        // so "between-bead" slides (Glory Be, Fatima, litanies) keep the ring colored.
        if (typeof RosaryRing !== 'undefined') {
            var currentBead = (slide.bead_index !== undefined) ? slide.bead_index : null;
            var lastBead    = getLastPrayedBead(index);
            RosaryRing.update(currentBead, lastBead);
        }

        // Scroll slide content back to top on each navigation
        var content = document.getElementById('slide-content');
        if (content) content.scrollTop = 0;

        // Update nav buttons
        btnPrev.disabled = (index === 0);
        btnNext.disabled = (index === total - 1);
    }

    function renderCover(slide) {
        setText('cover-title', slide.title);
        setText('cover-body',  slide.all);

        var photoWrap = document.getElementById('cover-photo-wrap');
        var photoImg  = document.getElementById('cover-photo');

        if (slide.photo_path && photoImg) {
            photoImg.src = slide.photo_path;
            photoImg.style.display = '';
            photoWrap.classList.remove('no-photo');
        } else {
            photoWrap.classList.add('no-photo');
        }
    }

    function renderPrayer(slide) {
        setText('slide-title', slide.title);

        var hasLeader = !!(slide.leader && slide.leader.trim());
        var hasAll    = !!(slide.all    && slide.all.trim());

        if (hasLeader) {
            showEl('leader-wrap');
            setText('leader-text', slide.leader);
        } else {
            hideEl('leader-wrap');
        }

        if (hasAll) {
            showEl('all-wrap');
            setText('all-text', slide.all);
        } else {
            hideEl('all-wrap');
        }

        // Bump font size when only one section is present
        var slideText = document.getElementById('slide-text');
        if (slideText) {
            if (hasLeader !== hasAll) {
                slideText.classList.add('single-section');
            } else {
                slideText.classList.remove('single-section');
            }
        }
    }

    function renderMystery(slide) {
        // title is like "The Third Sorrowful Mystery"
        // leader is the name of the mystery
        // all is the fruit/intention
        setText('mystery-number', slide.title);
        setText('mystery-title',  slide.leader);
        setText('mystery-fruit',  slide.all);
    }

    function renderLitany(slide) {
        setText('litany-title', slide.title);

        var hasLeader = !!(slide.leader && slide.leader.trim());
        var hasAll    = !!(slide.all    && slide.all.trim());

        if (hasLeader) {
            showEl('litany-leader-wrap');
            setText('litany-leader', slide.leader);
        } else {
            hideEl('litany-leader-wrap');
        }

        if (hasAll) {
            showEl('litany-all-wrap');
            setText('litany-all', slide.all);
        } else {
            hideEl('litany-all-wrap');
        }
    }

    function renderClosing(slide) {
        setText('closing-title',    slide.title);
        setText('closing-subtitle', slide.subtitle || '');
        setText('closing-body',     slide.all);

        var photoWrap = document.getElementById('closing-photo-wrap');
        var photoImg  = document.getElementById('closing-photo');
        if (slide.photo_path && photoImg) {
            photoImg.src = slide.photo_path;
            photoWrap.style.display = '';
        } else if (photoWrap) {
            photoWrap.style.display = 'none';
        }
    }

    // --------------------------------------------------------------------------
    // fitTextToScreen — shrink prayer/litany text until the slide fits on screen
    // without a scrollbar.  Uses binary search over pixel font-size.
    // Called after every render so long prayers (e.g. Day 5 novena, Concluding
    // Prayer) automatically scale down rather than requiring a scroll.
    // --------------------------------------------------------------------------
    var FIT_TEXT_ELS = '#leader-text, #all-text, #litany-leader, #litany-all, #closing-body';
    var FIT_MIN_PX   = 22;   // floor — stay readable for Zoom / projector audiences

    function fitTextToScreen() {
        var container = document.getElementById('slide-content');
        if (!container) return;

        var textEls = container.querySelectorAll(FIT_TEXT_ELS);

        // Reset any previous override so we measure the natural (CSS) size
        for (var k = 0; k < textEls.length; k++) {
            textEls[k].style.fontSize = '';
        }

        // Already fits — nothing to do
        if (container.scrollHeight <= container.clientHeight + 2) return;

        if (!textEls.length) return; // no adjustable text (cover, mystery, etc.)

        // Upper bound = current computed size; lower bound = readable minimum
        var naturalPx = parseFloat(window.getComputedStyle(textEls[0]).fontSize);
        var lo = FIT_MIN_PX;
        var hi = naturalPx;

        // Binary search: 20 iterations converges to < 0.1 px accuracy
        for (var iter = 0; iter < 20; iter++) {
            var mid = (lo + hi) / 2;
            for (var k = 0; k < textEls.length; k++) {
                textEls[k].style.fontSize = mid + 'px';
            }
            if (container.scrollHeight <= container.clientHeight + 2) {
                lo = mid;   // fits — try a touch larger
            } else {
                hi = mid;   // overflows — try smaller
            }
        }

        // Lock in the converged size
        for (var k = 0; k < textEls.length; k++) {
            textEls[k].style.fontSize = lo + 'px';
        }
    }

    function updateCounter(index) {
        var prayerTotal = total - 1; // exclude cover
        if (index === 0) {
            slideCounter.textContent = '';
        } else {
            slideCounter.textContent = 'Prayer ' + index + ' of ' + prayerTotal;
        }
    }

    function updateRepeatBadge(index) {
        // Hide every badge first (avoid NodeList.forEach for compatibility)
        var allBadges = document.querySelectorAll('.repeat-badge');
        for (var k = 0; k < allBadges.length; k++) {
            allBadges[k].style.display = 'none';
            allBadges[k].textContent   = '';
        }

        var slide = slides[index];

        // Part badge takes priority (long prayer split across slides)
        var badgeText = '';
        if (slide._partNum) {
            badgeText = 'Part ' + slide._partNum + ' / ' + slide._partTotal;
        } else {
            var run = slideRunInfo[index];
            if (run) badgeText = run.pos + ' of ' + run.total;
        }
        if (!badgeText) return;

        // Show the badge inside the currently-visible slide panel
        var panelId = (slide.type === 'litany') ? 'litany-slide' : 'prayer-slide';
        var panel   = document.getElementById(panelId);
        var badge   = panel ? panel.querySelector('.repeat-badge') : null;
        if (badge) {
            badge.textContent   = badgeText;
            badge.style.display = '';
        }
    }

    // --------------------------------------------------------------------------
    // Navigation
    // --------------------------------------------------------------------------
    function goTo(index) {
        if (index < 0 || index >= total) return;
        currentIndex = index;
        render(currentIndex);
        // Play audio for this slide (stops previous audio automatically)
        playSlideAudio(slides[index]);
        // Persist position so the user can resume after exiting.
        // Clear it when they reach the closing slide (rosary complete).
        try {
            if (index > 0 && index < total - 1) {
                localStorage.setItem(RESUME_KEY, index);
            } else {
                localStorage.removeItem(RESUME_KEY);
            }
        } catch (e) { /* storage unavailable */ }
    }

    function prev() { goTo(currentIndex - 1); }
    function next() { goTo(currentIndex + 1); }

    btnPrev.addEventListener('click', prev);
    btnNext.addEventListener('click', next);

    if (btnExit) {
        btnExit.addEventListener('click', function () {
            // Position already saved by goTo; navigate back
            window.location.href = window.BACK_URL || '/';
        });
    }

    // Keyboard
    document.addEventListener('keydown', function (e) {
        switch (e.key) {
            case 'ArrowRight':
            case 'ArrowDown':
            case ' ':
                e.preventDefault();
                next();
                break;
            case 'ArrowLeft':
            case 'ArrowUp':
                e.preventDefault();
                prev();
                break;
            case 'f':
            case 'F':
                toggleFullscreen();
                break;
        }
    });

    // Touch swipe
    var touchStartX = null;
    var touchStartY = null;

    document.addEventListener('touchstart', function (e) {
        touchStartX = e.touches[0].clientX;
        touchStartY = e.touches[0].clientY;
    }, { passive: true });

    document.addEventListener('touchend', function (e) {
        if (touchStartX === null) return;
        var dx = e.changedTouches[0].clientX - touchStartX;
        var dy = e.changedTouches[0].clientY - touchStartY;

        // Only respond to mostly-horizontal swipes
        if (Math.abs(dx) > Math.abs(dy) && Math.abs(dx) > 40) {
            if (dx < 0) next();
            else         prev();
        }
        touchStartX = null;
        touchStartY = null;
    }, { passive: true });

    // Fullscreen
    function toggleFullscreen() {
        if (!document.fullscreenElement) {
            document.documentElement.requestFullscreen().catch(function () {});
        } else {
            document.exitFullscreen().catch(function () {});
        }
    }

    // Re-fit text when the window is resized (e.g. projector moved to a
    // different monitor, fullscreen toggled, or phone rotated).
    var resizeTimer = null;
    window.addEventListener('resize', function () {
        clearTimeout(resizeTimer);
        resizeTimer = setTimeout(function () { render(currentIndex); }, 150);
    });

    // --------------------------------------------------------------------------
    // Initialize
    // --------------------------------------------------------------------------

    // Check for a saved resume position
    var resumeIndex = 0;
    try {
        var saved = localStorage.getItem(RESUME_KEY);
        if (saved !== null) {
            var parsed = parseInt(saved, 10);
            if (!isNaN(parsed) && parsed > 0 && parsed < total - 1) {
                resumeIndex = parsed;
            }
        }
    } catch (e) { /* storage unavailable */ }

    render(resumeIndex);
    currentIndex = resumeIndex;

    // Show fade-out toast if resuming mid-prayer
    if (resumeIndex > 0 && resumeToast) {
        resumeToast.textContent = 'Resumed at prayer ' + resumeIndex + ' of ' + (total - 1);
        resumeToast.classList.add('visible');
        setTimeout(function () {
            resumeToast.classList.remove('visible');
        }, 2800);
    }

    // Wire bead clicks: jump to the first slide that uses that bead
    if (typeof RosaryRing !== 'undefined' && RosaryRing.onBeadClick) {
        RosaryRing.onBeadClick(function (beadIndex) {
            if (beadIndex in beadToSlide) {
                goTo(beadToSlide[beadIndex]);
            }
        });
    }

})();