app.js

// Utility & feedback helpers
function speakCue(text) {
    try {
        if ('speechSynthesis' in window) {
            const utter = new SpeechSynthesisUtterance(text);
            utter.rate = 1.05;
            window.speechSynthesis.speak(utter);
        }
    } catch(e) {}
}
function vibrate(pattern) { if (navigator.vibrate) navigator.vibrate(pattern); }
function formatTime(seconds) { const m = Math.floor(seconds/60); const s = seconds % 60; return `${m}:${s.toString().padStart(2,'0')}`; }

// Save workout completion
function markWorkoutComplete(week, day){
    let progress = JSON.parse(localStorage.getItem('c25k_progress')||'{}');
    if(!progress[week]) progress[week]={};
    progress[week][day]=true;
    localStorage.setItem('c25k_progress', JSON.stringify(progress));
}
// Couch to 5K Trainer App
// Basic structure and event listeners

document.addEventListener('DOMContentLoaded', function() {
    const sections = {
        home: document.getElementById('home'),
        schedule: document.getElementById('schedule'),
        workout: document.getElementById('workout'),
        progress: document.getElementById('progress')
    };
    const settingsPanel = document.getElementById('settingsPanel');
    const openSettingsBtn = document.getElementById('openSettingsBtn');
    const closeSettingsBtn = document.getElementById('closeSettingsBtn');
    const nav = document.getElementById('mainNav');

    function showSection(name){
        Object.entries(sections).forEach(([key,el])=>{
            if(!el) return;
            if(key===name){
                el.hidden=false;
                el.classList.add('fadeIn');
                setTimeout(()=>el.classList.remove('fadeIn'),400);
            } else {
                el.hidden=true;
            }
        });
        localStorage.setItem('c25k_last_section', name);
    }
    function setActiveNav(name){
        if(!nav) return; nav.querySelectorAll('.navBtn').forEach(btn=>{
            const target = btn.getAttribute('data-section');
            if(target===name) btn.classList.add('active'); else btn.classList.remove('active');
        });
    }
    if(nav){
        nav.querySelectorAll('.navBtn').forEach(btn=>{
            btn.addEventListener('click', ()=>{
                const target = btn.getAttribute('data-section');
                if(target==='settingsPanel') { settingsPanel.hidden=false; settingsPanel.focus(); return; }
                settingsPanel.hidden = true;
                showSection(target);
                setActiveNav(target);
                if(target==='schedule' && !sections.schedule.dataset.rendered) renderSchedule();
                if(target==='progress') renderProgress();
            });
        });
        const last = localStorage.getItem('c25k_last_section') || 'home';
        setActiveNav(last);
        showSection(last);
    }

    // Settings panel (initial assignment already above)
    // Ensure settings gear always opens panel (will rewire later too)
    if(openSettingsBtn) openSettingsBtn.addEventListener('click', ()=>{ openSettings(); });
    if(closeSettingsBtn) closeSettingsBtn.onclick = ()=>{ closeSettings(); };
    function openSettings(){ settingsPanel.hidden=false; trapFocus(settingsPanel); }
    function closeSettings(){ settingsPanel.hidden=true; releaseFocus(); openSettingsBtn.focus(); }
    // Settings logic continued
    const timerSpeedInput = document.getElementById('timerSpeed');
    const timerSpeedValue = document.getElementById('timerSpeedValue');
    const soundVolumeInput = document.getElementById('soundVolume');
    const soundVolumeValue = document.getElementById('soundVolumeValue');
    const colorThemeSelect = document.getElementById('colorTheme');
    const beepToneSelect = document.getElementById('beepToneSelect');
    const resetProgressBtn = document.getElementById('resetProgressBtn');
    const avgPaceInput = document.getElementById('avgPaceInput');
    const autoNextCheckbox = document.getElementById('autoNextCheckbox');
    const enhancedHapticsCheckbox = document.getElementById('enhancedHapticsCheckbox');
    const exportProgressBtn = document.getElementById('exportProgressBtn');
    const importProgressBtn = document.getElementById('importProgressBtn');
    const importProgressFile = document.getElementById('importProgressFile');
    const installAppBtn = document.getElementById('installAppBtn');
    const weightInput = document.getElementById('weightInput');
    const weightUnitSelect = document.getElementById('weightUnitSelect');
    const hydrationCheckbox = document.getElementById('hydrationReminderCheckbox');
    const batterySaverCheckbox = document.getElementById('batterySaverCheckbox');
    const shareImageBtn = document.getElementById('shareImageBtn');
    // Load settings
    if (localStorage.getItem('c25k_timer_speed')) timerSpeedInput.value = localStorage.getItem('c25k_timer_speed');
    if (localStorage.getItem('c25k_sound_volume')) soundVolumeInput.value = localStorage.getItem('c25k_sound_volume');
    if (localStorage.getItem('c25k_color_theme')) colorThemeSelect.value = localStorage.getItem('c25k_color_theme');
    if (localStorage.getItem('c25k_beep_tone')) beepToneSelect.value = localStorage.getItem('c25k_beep_tone');
    if (localStorage.getItem('c25k_avg_pace')) avgPaceInput.value = localStorage.getItem('c25k_avg_pace');
    if (localStorage.getItem('c25k_auto_next')) autoNextCheckbox.checked = localStorage.getItem('c25k_auto_next')==='1';
    if (localStorage.getItem('c25k_enhanced_haptics')) enhancedHapticsCheckbox.checked = localStorage.getItem('c25k_enhanced_haptics')==='1';
    if (localStorage.getItem('c25k_weight')) weightInput.value = localStorage.getItem('c25k_weight');
    if (localStorage.getItem('c25k_weight_unit')) weightUnitSelect.value = localStorage.getItem('c25k_weight_unit');
    if (localStorage.getItem('c25k_hydration')) hydrationCheckbox.checked = localStorage.getItem('c25k_hydration')==='1';
    if (localStorage.getItem('c25k_battery_saver')==='1'){ batterySaverCheckbox.checked=true; document.body.classList.add('battery-saver'); }
    timerSpeedValue.textContent = timerSpeedInput.value + 'x';
    soundVolumeValue.textContent = Math.round(soundVolumeInput.value * 100) + '%';
    // Open/close panel
    if(openSettingsBtn) openSettingsBtn.onclick = function() { openSettings(); };
    closeSettingsBtn.onclick = function() { closeSettings(); };
    // Update settings
    timerSpeedInput.oninput = function() {
        timerSpeedValue.textContent = timerSpeedInput.value + 'x';
        localStorage.setItem('c25k_timer_speed', timerSpeedInput.value);
    };
    soundVolumeInput.oninput = function() {
        soundVolumeValue.textContent = Math.round(soundVolumeInput.value * 100) + '%';
        localStorage.setItem('c25k_sound_volume', soundVolumeInput.value);
    };
    colorThemeSelect.onchange = function() {
        localStorage.setItem('c25k_color_theme', colorThemeSelect.value);
        applyTheme(colorThemeSelect.value);
    };
    beepToneSelect.onchange = function(){
        localStorage.setItem('c25k_beep_tone', beepToneSelect.value);
        speakCue(`${beepToneSelect.value} tone selected`);
    };
    avgPaceInput.oninput = function(){
        if(avgPaceInput.value){ localStorage.setItem('c25k_avg_pace', avgPaceInput.value); }
    };
    autoNextCheckbox.onchange = function(){ localStorage.setItem('c25k_auto_next', autoNextCheckbox.checked?'1':'0'); };
    enhancedHapticsCheckbox.onchange = function(){ localStorage.setItem('c25k_enhanced_haptics', enhancedHapticsCheckbox.checked?'1':'0'); };
    weightInput.oninput = function(){ if(weightInput.value) localStorage.setItem('c25k_weight', weightInput.value); };
    weightUnitSelect.onchange = function(){ localStorage.setItem('c25k_weight_unit', weightUnitSelect.value); };
    hydrationCheckbox.onchange = function(){ localStorage.setItem('c25k_hydration', hydrationCheckbox.checked?'1':'0'); };
    batterySaverCheckbox.onchange = function(){ localStorage.setItem('c25k_battery_saver', batterySaverCheckbox.checked?'1':'0'); document.body.classList.toggle('battery-saver', batterySaverCheckbox.checked); };
    if(exportProgressBtn){
        exportProgressBtn.onclick=()=>{
            const data = {
                progress: JSON.parse(localStorage.getItem('c25k_progress')||'{}'),
                settings: {
                    timer_speed: localStorage.getItem('c25k_timer_speed'),
                    sound_volume: localStorage.getItem('c25k_sound_volume'),
                    color_theme: localStorage.getItem('c25k_color_theme'),
                    beep_tone: localStorage.getItem('c25k_beep_tone'),
                    avg_pace: localStorage.getItem('c25k_avg_pace'),
                    auto_next: localStorage.getItem('c25k_auto_next'),
                    enhanced_haptics: localStorage.getItem('c25k_enhanced_haptics')
                }
            };
            const blob = new Blob([JSON.stringify(data,null,2)], {type:'application/json'});
            const url = URL.createObjectURL(blob);
            const a = document.createElement('a'); a.href=url; a.download='c25k-progress.json'; a.click(); URL.revokeObjectURL(url);
        };
    }
    if(importProgressBtn && importProgressFile){
        importProgressBtn.onclick=()=> importProgressFile.click();
        importProgressFile.onchange=(e)=>{
            const file = e.target.files[0]; if(!file) return;
            const reader = new FileReader();
            reader.onload=()=>{
                try{
                    const data = JSON.parse(reader.result);
                    if(data.progress){ localStorage.setItem('c25k_progress', JSON.stringify(data.progress)); }
                    if(data.settings){
                        Object.entries(data.settings).forEach(([k,v])=>{
                            if(v!==undefined && v!==null) localStorage.setItem('c25k_'+k, v);
                        });
                    }
                    alert('Import successful. Reloading...'); location.reload();
                }catch(err){ alert('Invalid file.'); }
            };
            reader.readAsText(file);
        };
    }
    if(resetProgressBtn){
        resetProgressBtn.onclick=()=>{
            if(confirm('Reset all workout progress? This cannot be undone.')){
                localStorage.removeItem('c25k_progress');
                alert('Progress reset.');
                const sec = document.getElementById('schedule');
                if(sec){ sec.dataset.rendered=''; sec.innerHTML=''; }
            }
        };
    }
    // Apply theme
    function applyTheme(theme) {
        if (theme === 'dark') {
            document.body.style.background = '#222';
            document.body.style.color = '#fff';
        } else if (theme === 'light') {
            document.body.style.background = '#fff';
            document.body.style.color = '#222';
        } else {
            document.body.style.background = '#f4f8fb';
            document.body.style.color = '#222';
        }
    }
    applyTheme(colorThemeSelect.value);
    // Reminder setup
    const reminderTimeInput = document.getElementById('reminderTime');
    const setReminderBtn = document.getElementById('setReminderBtn');
    if (setReminderBtn && reminderTimeInput) {
        // Load saved reminder time
        const savedTime = localStorage.getItem('c25k_reminder_time');
        if (savedTime) reminderTimeInput.value = savedTime;
        setReminderBtn.onclick = function() {
            const time = reminderTimeInput.value;
            if (!time) {
                alert('Please select a time for your reminder.');
                return;
            }
            localStorage.setItem('c25k_reminder_time', time);
            // Request notification permission
            if (Notification && Notification.permission !== 'granted') {
                Notification.requestPermission().then(function(permission) {
                    if (permission === 'granted') {
                        alert('Reminder set! You will be notified at ' + time + ' each day.');
                    } else {
                        alert('Notifications are blocked. Please enable them in your browser settings.');
                    }
                });
            } else {
                alert('Reminder set! You will be notified at ' + time + ' each day.');
            }
        };
        // Schedule notification check every minute
        setInterval(function() {
            const time = localStorage.getItem('c25k_reminder_time');
            if (!time || Notification.permission !== 'granted') return;
            const now = new Date();
            const [h, m] = time.split(':');
            if (now.getHours() === parseInt(h) && now.getMinutes() === parseInt(m)) {
                // Only notify once per day
                const lastNotified = localStorage.getItem('c25k_last_notified');
                const today = now.toISOString().slice(0,10);
                if (lastNotified !== today) {
                    new Notification('Couch to 5K', { body: 'Time for your workout! 🏃‍♂️' });
                    localStorage.setItem('c25k_last_notified', today);
                }
            }
        }, 60000);
    }
    const startBtn = document.getElementById('startBtn');
    if(startBtn) startBtn.addEventListener('click', ()=>{ showSection('schedule'); setActiveNav('schedule'); if(!sections.schedule.dataset.rendered) renderSchedule(); });

    // (removed duplicate renderSchedule)
    function renderSchedule() {
        const weeks = 9;
        const daysPerWeek = 3;
        let progress = JSON.parse(localStorage.getItem('c25k_progress') || '{}');
        let html = '<h2>Choose Your Workout</h2><div class="weeks">';
        for (let w = 1; w <= weeks; w++) {
            html += `<div class="week"><strong>Week ${w}</strong><div class="days">`;
            for (let d = 1; d <= daysPerWeek; d++) {
                let done = progress[w] && progress[w][d];
                html += `<button class="dayBtn" data-week="${w}" data-day="${d}" aria-pressed="${!!done}" ${done? 'disabled':''}>Day ${d}${done ? ' ✓' : ''}</button>`;
            }
            html += '</div></div>';
        }
        html += '</div>';
        sections.schedule.innerHTML = html;
        sections.schedule.dataset.rendered = '1';

        // Add event listeners for day buttons
        document.querySelectorAll('.dayBtn').forEach(btn => {
            btn.addEventListener('click', function() {
                const week = this.getAttribute('data-week');
                const day = this.getAttribute('data-day');
                showSection('workout');
                setActiveNav('workout');
                startWorkout(week, day);
            });
        });
    }

    // Prepare workout screen but keep Start button disabled until a workout is loaded
    const globalStartBtn = document.getElementById('startIntervalBtn');
    if(globalStartBtn){
        globalStartBtn.disabled = true;
        globalStartBtn.title = 'Select a week/day from Schedule first';
        globalStartBtn.addEventListener('click', function(){
            if(this.disabled){
                speakCue('Pick a workout from the schedule first');
            }
        }, { once:false });
    }

    function startWorkout(week, day) {
        const canvas = document.getElementById('progressCanvas');
        const playMusicBtn = document.getElementById('playMusicBtn');
        // Legacy audio element removed in favor of external streaming launch
        const intervalCueEl = document.getElementById('intervalCue');
        const timerDisplayEl = document.getElementById('timerDisplay');
        const startIntervalBtn = document.getElementById('startIntervalBtn');
        initMusicLauncher();
        const intervalPlanWrap = document.getElementById('intervalPlanWrap');
        const intervalPlanList = document.getElementById('intervalPlanList');
        const intervalTotalTimeEl = document.getElementById('intervalTotalTime');
        // Full Couch to 5K interval definitions for Weeks 1-9
        // Source: NHS/C25K standard plans
        const workouts = {
            1: [
                Array(1).fill().map(() => [
                    { type: 'Warmup Walk', duration: 300 },
                    ...Array(8).fill().flatMap(() => [
                        { type: 'Run', duration: 60 },
                        { type: 'Walk', duration: 90 }
                    ]),
                    { type: 'Cooldown Walk', duration: 300 }
                ])[0],
                Array(1).fill().map(() => [
                    { type: 'Warmup Walk', duration: 300 },
                    ...Array(8).fill().flatMap(() => [
                        { type: 'Run', duration: 60 },
                        { type: 'Walk', duration: 90 }
                    ]),
                    { type: 'Cooldown Walk', duration: 300 }
                ])[0],
                Array(1).fill().map(() => [
                    { type: 'Warmup Walk', duration: 300 },
                    ...Array(8).fill().flatMap(() => [
                        { type: 'Run', duration: 60 },
                        { type: 'Walk', duration: 90 }
                    ]),
                    { type: 'Cooldown Walk', duration: 300 }
                ])[0]
            ],
            2: [
                Array(1).fill().map(() => [
                    { type: 'Warmup Walk', duration: 300 },
                    ...Array(6).fill().flatMap(() => [
                        { type: 'Run', duration: 90 },
                        { type: 'Walk', duration: 120 }
                    ]),
                    { type: 'Cooldown Walk', duration: 300 }
                ])[0],
                Array(1).fill().map(() => [
                    { type: 'Warmup Walk', duration: 300 },
                    ...Array(6).fill().flatMap(() => [
                        { type: 'Run', duration: 90 },
                        { type: 'Walk', duration: 120 }
                    ]),
                    { type: 'Cooldown Walk', duration: 300 }
                ])[0],
                Array(1).fill().map(() => [
                    { type: 'Warmup Walk', duration: 300 },
                    ...Array(6).fill().flatMap(() => [
                        { type: 'Run', duration: 90 },
                        { type: 'Walk', duration: 120 }
                    ]),
                    { type: 'Cooldown Walk', duration: 300 }
                ])[0]
            ],
            3: [
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 90 },
                    { type: 'Walk', duration: 90 },
                    { type: 'Run', duration: 180 },
                    { type: 'Walk', duration: 180 },
                    { type: 'Run', duration: 90 },
                    { type: 'Walk', duration: 90 },
                    { type: 'Run', duration: 180 },
                    { type: 'Walk', duration: 180 },
                    { type: 'Cooldown Walk', duration: 300 }
                ],
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 90 },
                    { type: 'Walk', duration: 90 },
                    { type: 'Run', duration: 180 },
                    { type: 'Walk', duration: 180 },
                    { type: 'Run', duration: 90 },
                    { type: 'Walk', duration: 90 },
                    { type: 'Run', duration: 180 },
                    { type: 'Walk', duration: 180 },
                    { type: 'Cooldown Walk', duration: 300 }
                ],
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 90 },
                    { type: 'Walk', duration: 90 },
                    { type: 'Run', duration: 180 },
                    { type: 'Walk', duration: 180 },
                    { type: 'Run', duration: 90 },
                    { type: 'Walk', duration: 90 },
                    { type: 'Run', duration: 180 },
                    { type: 'Walk', duration: 180 },
                    { type: 'Cooldown Walk', duration: 300 }
                ]
            ],
            4: [
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 180 },
                    { type: 'Walk', duration: 90 },
                    { type: 'Run', duration: 300 },
                    { type: 'Walk', duration: 150 },
                    { type: 'Run', duration: 180 },
                    { type: 'Walk', duration: 90 },
                    { type: 'Run', duration: 300 },
                    { type: 'Cooldown Walk', duration: 300 }
                ],
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 180 },
                    { type: 'Walk', duration: 90 },
                    { type: 'Run', duration: 300 },
                    { type: 'Walk', duration: 150 },
                    { type: 'Run', duration: 180 },
                    { type: 'Walk', duration: 90 },
                    { type: 'Run', duration: 300 },
                    { type: 'Cooldown Walk', duration: 300 }
                ],
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 180 },
                    { type: 'Walk', duration: 90 },
                    { type: 'Run', duration: 300 },
                    { type: 'Walk', duration: 150 },
                    { type: 'Run', duration: 180 },
                    { type: 'Walk', duration: 90 },
                    { type: 'Run', duration: 300 },
                    { type: 'Cooldown Walk', duration: 300 }
                ]
            ],
            5: [
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 300 },
                    { type: 'Walk', duration: 180 },
                    { type: 'Run', duration: 300 },
                    { type: 'Walk', duration: 180 },
                    { type: 'Run', duration: 300 },
                    { type: 'Cooldown Walk', duration: 300 }
                ],
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 600 },
                    { type: 'Walk', duration: 300 },
                    { type: 'Run', duration: 600 },
                    { type: 'Cooldown Walk', duration: 300 }
                ],
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 1200 },
                    { type: 'Cooldown Walk', duration: 300 }
                ]
            ],
            6: [
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 300 },
                    { type: 'Walk', duration: 90 },
                    { type: 'Run', duration: 600 },
                    { type: 'Walk', duration: 90 },
                    { type: 'Run', duration: 300 },
                    { type: 'Cooldown Walk', duration: 300 }
                ],
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 600 },
                    { type: 'Walk', duration: 120 },
                    { type: 'Run', duration: 600 },
                    { type: 'Cooldown Walk', duration: 300 }
                ],
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 1500 },
                    { type: 'Cooldown Walk', duration: 300 }
                ]
            ],
            7: [
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 1500 },
                    { type: 'Cooldown Walk', duration: 300 }
                ],
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 1500 },
                    { type: 'Cooldown Walk', duration: 300 }
                ],
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 1500 },
                    { type: 'Cooldown Walk', duration: 300 }
                ]
            ],
            8: [
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 1680 },
                    { type: 'Cooldown Walk', duration: 300 }
                ],
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 1800 },
                    { type: 'Cooldown Walk', duration: 300 }
                ],
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 1800 },
                    { type: 'Cooldown Walk', duration: 300 }
                ]
            ],
            9: [
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 1800 },
                    { type: 'Cooldown Walk', duration: 300 }
                ],
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 1800 },
                    { type: 'Cooldown Walk', duration: 300 }
                ],
                [
                    { type: 'Warmup Walk', duration: 300 },
                    { type: 'Run', duration: 1800 },
                    { type: 'Cooldown Walk', duration: 300 }
                ]
            ]
        };

        week = parseInt(week); day = parseInt(day);
        const intervals = workouts[week][day-1];
        if(!intervals) { intervalCueEl.textContent = 'Workout not found'; return; }
        if(canvas) canvas.style.display='block';
        // Build interval plan list before starting
        if(intervalPlanWrap && intervalPlanList){
            intervalPlanWrap.hidden = false;
            let total = 0;
            intervalPlanList.innerHTML = intervals.map((iv, idx)=>{ total += iv.duration; const cls = intervalTypeClass(iv.type); return `<li data-idx="${idx}" class="${cls}"><span class="intervalType">${iv.type}</span><span class="intervalDur">${formatTime(iv.duration)}</span></li>`; }).join('');
            if(intervalTotalTimeEl) intervalTotalTimeEl.textContent = formatTime(total);
        }
        if(startIntervalBtn){
            startIntervalBtn.disabled=false;
            startIntervalBtn.title='Start this workout';
            startIntervalBtn.onclick=()=> beginIntervals(intervals, week, day, {canvas, intervalCueEl, timerDisplayEl});
        }
        const toggleBtn = document.getElementById('toggleIntervalPlanBtn');
        if(toggleBtn && intervalPlanWrap){
            toggleBtn.onclick=()=>{
                const collapsed = intervalPlanWrap.classList.toggle('collapsed');
                toggleBtn.textContent = collapsed? 'Expand':'Collapse';
                toggleBtn.setAttribute('aria-expanded', (!collapsed).toString());
            };
        }
    }

    function beginIntervals(intervals, week, day, ctxRefs){
        const {canvas, intervalCueEl, timerDisplayEl} = ctxRefs;
        const intervalPlanList = document.getElementById('intervalPlanList');
        const planItems = intervalPlanList ? Array.from(intervalPlanList.querySelectorAll('li')) : [];
        const remainingEl = document.getElementById('remainingIntervals');
        const totalIntervals = intervals.length;
        let current = 0;
        let timeLeft = intervals[0].duration;
        intervalCueEl.textContent = intervals[0].type;
        timerDisplayEl.textContent = formatTime(timeLeft);
        drawProgress(canvas,0,timeLeft,intervals[0].type);
    speakCue(`Start ${intervals[0].type}`); doHaptics('start'); playBeep();
        if(planItems.length){ planItems[0].classList.add('active'); }
        let last = Date.now();
        let speed = parseFloat(localStorage.getItem('c25k_timer_speed')||'1');
        const workoutControls = document.getElementById('workoutControls');
        if(workoutControls) workoutControls.style.display='flex';
        let paused=false, stopped=false;
    let announcedHalf=false; let intervalHalfTarget = intervals[current].duration/2;
    const pauseBtn=document.getElementById('pauseWorkoutBtn');
    const stopBtn=document.getElementById('stopWorkoutBtn');
    const skipBtn=document.getElementById('skipIntervalBtn');
    if(pauseBtn) pauseBtn.onclick=()=>{ paused=!paused; pauseBtn.textContent=paused?'Resume':'Pause Workout'; };
    if(stopBtn) stopBtn.onclick=()=>{ stopped=true; cleanup(); };
    if(skipBtn) skipBtn.onclick=()=>{ if(!stopped){ timeLeft=0; } };
        const timer = setInterval(()=>{
            if(stopped) return clearInterval(timer);
            if(paused) { last=Date.now(); return; }
            const now=Date.now();
            if(now-last >= 1000/speed){
                timeLeft--; last=now;
                if(timeLeft<0) timeLeft=0;
                timerDisplayEl.textContent = formatTime(timeLeft);
                if(remainingEl) remainingEl.textContent = `Remaining: ${totalIntervals-current}/${totalIntervals}`;
                if(!announcedHalf && timeLeft===Math.floor(intervalHalfTarget)){
                    // Halfway cue for long segments (>= 5 min)
                    if(intervals[current].duration >= 300){ speakCue('Halfway'); doHaptics('transition'); }
                    announcedHalf=true;
                }
                drawProgress(canvas,1-(timeLeft/intervals[current].duration),timeLeft,intervals[current].type);
                // Pre-cue next interval at 5s remaining
                if(timeLeft===5 && current < intervals.length-1){ speakCue(`Next ${intervals[current+1].type}`); }
                if(timeLeft===0){
                    current++;
                    if(current<intervals.length){
                        timeLeft = intervals[current].duration;
                        intervalCueEl.textContent = intervals[current].type;
                        speakCue(`Start ${intervals[current].type}`); doHaptics('transition'); playBeep();
                        drawProgress(canvas,0,timeLeft,intervals[current].type);
                        if(planItems.length){
                            planItems.forEach((li,i)=>{
                                li.classList.toggle('active', i===current);
                                if(i<current) li.classList.add('completed');
                            });
                        }
                        announcedHalf=false; intervalHalfTarget = intervals[current].duration/2;
                    } else {
                        intervalCueEl.textContent = 'Workout Complete!';
                        timerDisplayEl.textContent = '';
                        drawProgress(canvas,1,0,'Complete');
                        playCelebrate(); doHaptics('complete'); markWorkoutComplete(week,day); cleanup();
                        if(localStorage.getItem('c25k_auto_next')==='1') scheduleNextAuto(week,day);
                        if(planItems.length){ planItems.forEach(li=>{ li.classList.remove('active'); li.classList.add('completed'); }); }
                    }
                }
            }
        },100);
        function cleanup(){
            clearInterval(timer);
            const workoutControls = document.getElementById('workoutControls');
            if(workoutControls) workoutControls.style.display='none';
        }
    }
    function scheduleNextAuto(week,day){
        let w=parseInt(week), d=parseInt(day);
        d++; if(d>3){ d=1; w++; }
        if(w>9) return;
        setTimeout(()=>{
            showSection('schedule'); setActiveNav('schedule');
            // ensure schedule rendered then auto-start next if available
            if(!document.getElementById('schedule').dataset.rendered) renderSchedule();
            const btn = document.querySelector(`.dayBtn[data-week='${w}'][data-day='${d}']`);
            if(btn && !btn.disabled){ btn.click(); setTimeout(()=>document.getElementById('startIntervalBtn')?.click(), 600); }
        }, 2500);
    }

    // Music launcher logic
    function initMusicLauncher(){
        const optionsWrap = document.getElementById('musicOptions');
        const launchRow = document.getElementById('launchMusicRow');
        const chosenSpan = document.getElementById('chosenMusicService');
        const launchBtn = document.getElementById('launchMusicBtn');
        const changeBtn = document.getElementById('changeMusicServiceBtn');
        if(!optionsWrap || !launchRow) return;
        const saved = localStorage.getItem('c25k_music_service');
        if(saved){
            chosenSpan.textContent = formatServiceName(saved);
            launchRow.hidden = false;
            optionsWrap.style.display='none';
        }
        optionsWrap.querySelectorAll('.musicServiceBtn').forEach(btn=>{
            btn.onclick=()=>{
                const service = btn.dataset.service;
                localStorage.setItem('c25k_music_service', service);
                chosenSpan.textContent = formatServiceName(service);
                launchRow.hidden = false;
                optionsWrap.style.display='none';
            };
        });
        if(changeBtn){
            changeBtn.onclick=()=>{
                launchRow.hidden = true;
                optionsWrap.style.display='flex';
            };
        }
        if(launchBtn){
            launchBtn.onclick=()=>{
                const svc = localStorage.getItem('c25k_music_service');
                if(!svc){ alert('Select a music service first.'); return; }
                const url = buildServiceUrl(svc);
                // Attempt open via protocol first for installed apps
                const protocolUrl = buildProtocolUrl(svc);
                let opened = false;
                if(protocolUrl){
                    const a = document.createElement('a');
                    a.href=protocolUrl;
                    a.style.display='none';
                    document.body.appendChild(a);
                    a.click();
                    setTimeout(()=>{ if(!opened) window.open(url,'_blank'); a.remove(); }, 800);
                } else {
                    window.open(url,'_blank');
                }
            };
        }
    }
    function formatServiceName(key){
        return key==='spotify'?'Spotify': key==='youtube'?'YouTube Music': key==='apple'?'Apple Music': key;
    }
    function buildServiceUrl(key){
        switch(key){
            case 'spotify': return 'https://open.spotify.com/search/running%20motivation';
            case 'youtube': return 'https://music.youtube.com/search?q=running%20workout%20playlist';
            case 'apple': return 'https://music.apple.com/us/search?term=running%20workout';
            default: return 'https://google.com/search?q=running+workout+music';
        }
    }
    function buildProtocolUrl(key){
        switch(key){
            case 'spotify': return 'spotify:search:running%20motivation';
            case 'apple': return null; // Apple Music protocol varies by device
            case 'youtube': return null; // YT Music protocol limited
            default: return null;
        }
    }

    // Focus trap utilities
    let lastFocusElement = null; let focusTrapActive=false;
    function trapFocus(container){
        lastFocusElement = document.activeElement;
        focusTrapActive=true;
        function handleKey(e){
            if(!focusTrapActive) return;
            if(e.key==='Escape'){ closeSettings(); }
            if(e.key==='Tab'){
                const focusable = container.querySelectorAll('button, [href], input, select, textarea, [tabindex]:not([tabindex="-1"])');
                const list = Array.from(focusable).filter(el=>!el.disabled && el.offsetParent!==null);
                if(!list.length) return;
                const first=list[0]; const last=list[list.length-1];
                if(e.shiftKey && document.activeElement===first){ e.preventDefault(); last.focus(); }
                else if(!e.shiftKey && document.activeElement===last){ e.preventDefault(); first.focus(); }
            }
        }
        container.addEventListener('keydown', handleKey);
    }
    function releaseFocus(){ focusTrapActive=false; if(lastFocusElement) lastFocusElement.focus(); }
});

// Inject fade animation styles if missing
(function injectFade(){
    if(document.getElementById('fadeStyles')) return;
    const style=document.createElement('style'); style.id='fadeStyles';
    style.textContent='.fadeIn{animation:fadeIn .35s ease both}@keyframes fadeIn{0%{opacity:0;transform:translateY(6px)}100%{opacity:1;transform:translateY(0)}}';
    document.head.appendChild(style);
})();

// PWA install & service worker
if('serviceWorker' in navigator){
    window.addEventListener('load', ()=>{
        navigator.serviceWorker.register('./sw.js').catch(()=>{});
    });
}
let deferredPrompt=null;
window.addEventListener('beforeinstallprompt', (e)=>{
    e.preventDefault();
    deferredPrompt=e;
    const btn=document.getElementById('installAppBtn');
    if(btn){ btn.hidden=false; btn.onclick=async ()=>{ btn.disabled=true; try{ await deferredPrompt.prompt(); }catch{} finally{ btn.hidden=true; } }; }
});

// Render progress data
function renderProgress(){
    const container = document.getElementById('progressContent');
    if(!container) return;
    let progress = JSON.parse(localStorage.getItem('c25k_progress')||'{}');
    let totalWorkouts=0;
    for(let w=1; w<=9; w++){
        for(let d=1; d<=3; d++) if(progress[w] && progress[w][d]) totalWorkouts++;
    }
    const avgPace = parseFloat(localStorage.getItem('c25k_avg_pace')||'11'); // minutes per mile
    // Estimate distance: assume avg 30 min early workouts scaling upward; use total seconds of completed intervals if we want precision
    // Simplified: 1 workout time average ~ (25 + (weekIndex*3)) minutes
    let estMinutes=0; let progressData = JSON.parse(localStorage.getItem('c25k_progress')||'{}');
    for(let w=1; w<=9; w++){
        for(let d=1; d<=3; d++) if(progressData[w] && progressData[w][d]) estMinutes += (25 + (w-1)*3);
    }
    const estMiles = (estMinutes/avgPace).toFixed(1);
    const weight = parseFloat(localStorage.getItem('c25k_weight')||'170');
    const unit = localStorage.getItem('c25k_weight_unit')||'lb';
    const weightKg = unit==='kg'? weight : weight * 0.45359237;
    // Rough calorie estimate: MET*weight(kg)*time(hr). Use MET 8 for running segments approximation.
    // Convert estMinutes to hours.
    const met = 8; const hours = estMinutes/60; const estCalories = Math.round(met * weightKg * hours);
    let html = `<p><strong>Total Workouts:</strong> ${totalWorkouts}<br><strong>Est. Distance:</strong> ${estMiles} mi<br><strong>Est. Calories:</strong> ${estCalories} kcal<br><strong>Avg Pace Setting:</strong> ${avgPace} min/mi<br><strong>Weight:</strong> ${weight} ${unit}</p>`;
    container.innerHTML = html;
    const shareBtn = document.getElementById('shareProgressBtn');
    if(shareBtn){
        shareBtn.onclick = ()=>{
            let shareText = `My Couch to 5K Progress: ${totalWorkouts} workouts, ${estMiles} miles, ${estCalories} kcal! #CouchTo5K`;
            if(navigator.share){ navigator.share({text:shareText}); }
            else { navigator.clipboard.writeText(shareText); alert('Progress copied to clipboard'); }
        };
    }
    const shareImageBtn = document.getElementById('shareImageBtn');
    if(shareImageBtn){
        shareImageBtn.onclick=()=> generateShareImage(totalWorkouts, estMiles, estCalories, avgPace);
    }
}
    // Simple beep sound for interval transitions
    function playBeep() {
        try {
            const ctx = new (window.AudioContext || window.webkitAudioContext)();
            const osc = ctx.createOscillator();
            const gain = ctx.createGain();
            const tone = localStorage.getItem('c25k_beep_tone') || 'sine';
            osc.type = tone;
            osc.frequency.value = 880;
            // Use settings volume
            let vol = parseFloat(localStorage.getItem('c25k_sound_volume') || '0.2');
            gain.gain.value = vol;
            osc.connect(gain);
            gain.connect(ctx.destination);
            osc.start();
            osc.stop(ctx.currentTime + 0.18);
            osc.onended = () => ctx.close();
        } catch (e) {}
    }

    // Celebration sound for workout completion
    function playCelebrate() {
        try {
            const ctx = new (window.AudioContext || window.webkitAudioContext)();
            const osc = ctx.createOscillator();
            const gain = ctx.createGain();
            osc.type = 'triangle';
            osc.frequency.setValueAtTime(440, ctx.currentTime);
            osc.frequency.linearRampToValueAtTime(1760, ctx.currentTime + 0.5);
            let vol = parseFloat(localStorage.getItem('c25k_sound_volume') || '0.2');
            gain.gain.value = vol;
            osc.connect(gain);
            gain.connect(ctx.destination);
            osc.start();
            osc.stop(ctx.currentTime + 0.6);
            osc.onended = () => ctx.close();
        } catch (e) {}
    }

// Draw circular progress bar
function drawProgress(canvas, percent, timeLeft, intervalType) {
    const ctx = canvas.getContext('2d');
    ctx.clearRect(0, 0, canvas.width, canvas.height);
    const centerX = canvas.width / 2;
    const centerY = canvas.height / 2;
    const radius = 60;
    // Background circle
    ctx.beginPath();
    ctx.arc(centerX, centerY, radius, 0, 2 * Math.PI);
    ctx.strokeStyle = '#e0e0e0';
    ctx.lineWidth = 10;
    ctx.stroke();
    // Progress arc with color transition
    const startColor = [33, 150, 243]; // blue
    const endColor = [67, 233, 123]; // green
    const r = Math.round(startColor[0] + (endColor[0] - startColor[0]) * percent);
    const g = Math.round(startColor[1] + (endColor[1] - startColor[1]) * percent);
    const b = Math.round(startColor[2] + (endColor[2] - startColor[2]) * percent);
    ctx.beginPath();
    ctx.arc(centerX, centerY, radius, -0.5 * Math.PI, (2 * Math.PI * percent) - 0.5 * Math.PI);
    ctx.strokeStyle = `rgb(${r},${g},${b})`;
    ctx.lineWidth = 10;
    ctx.stroke();
    // Inner circle
    ctx.beginPath();
    ctx.arc(centerX, centerY, radius - 18, 0, 2 * Math.PI);
    ctx.fillStyle = '#fff';
    ctx.fill();
    // Timer text
    ctx.font = 'bold 2em Segoe UI, Arial';
    ctx.fillStyle = '#2196f3';
    ctx.textAlign = 'center';
    ctx.textBaseline = 'middle';
    ctx.fillText(timeLeft > 0 ? timeLeft : '', centerX, centerY - 10);
    // Interval type text
    ctx.font = '1em Segoe UI, Arial';
    ctx.fillStyle = '#43e97b';
    ctx.fillText(intervalType, centerX, centerY + 22);
}

function doHaptics(kind){
    const enhanced = localStorage.getItem('c25k_enhanced_haptics')==='1';
    if(!navigator.vibrate) return;
    if(!enhanced){
        if(kind==='complete') vibrate([200,100,200]); else vibrate(200);
        return;
    }
    switch(kind){
        case 'start': vibrate([80,40,80]); break;
        case 'transition': vibrate([60,30,60]); break;
        case 'complete': vibrate([120,60,120,60,200]); break;
        default: vibrate(150);
    }
}

// Hydration reminder loop (every 7 minutes during workout if enabled)
let hydrationIntervalRef=null;
function startHydrationReminders(){
    if(localStorage.getItem('c25k_hydration')!=='1') return;
    clearInterval(hydrationIntervalRef);
    hydrationIntervalRef = setInterval(()=>{
        speakCue('Hydrate if needed'); doHaptics('transition');
    }, 7*60*1000);
}
function stopHydrationReminders(){ clearInterval(hydrationIntervalRef); }

// Enhance beginIntervals to start/stop hydration reminders
(function patchHydration(){
    const originalBegin = beginIntervals;
    beginIntervals = function(intervals, week, day, ctxRefs){
        startHydrationReminders();
        originalBegin(intervals, week, day, ctxRefs);
        // monkey patch cleanup to also stop hydration when workout complete; we wrap cleanup by observing haptics complete (markWorkoutComplete already called)
        const stopFn = stopHydrationReminders; // captured
        const observer = new MutationObserver(()=>{
            const cue=document.getElementById('intervalCue');
            if(cue && cue.textContent.includes('Complete')){ stopFn(); observer.disconnect(); }
        });
        observer.observe(document.body,{subtree:true,childList:true,characterData:true});
    };
})();

// Generate shareable image (canvas) with stats
function generateShareImage(totalWorkouts, estMiles, estCalories, avgPace){
    try {
        const w=800, h=420; const cvs=document.createElement('canvas'); cvs.width=w; cvs.height=h; const ctx=cvs.getContext('2d');
        ctx.fillStyle='#111'; ctx.fillRect(0,0,w,h);
        const grad=ctx.createLinearGradient(0,0,w,h); grad.addColorStop(0,'#1d4ed8'); grad.addColorStop(1,'#0f172a'); ctx.fillStyle=grad; ctx.fillRect(0,0,w,h);
        ctx.fillStyle='#fff'; ctx.font='700 42px Inter, Segoe UI, Arial'; ctx.fillText('Couch to 5K Progress',40,70);
        ctx.font='400 22px Inter, Segoe UI, Arial';
        const lines=[`Workouts: ${totalWorkouts}`,`Distance: ${estMiles} mi`,`Calories: ${estCalories} kcal`,`Avg Pace: ${avgPace} min/mi`];
        lines.forEach((l,i)=> ctx.fillText(l,40,140+i*40));
        ctx.font='600 18px Inter, Segoe UI, Arial'; ctx.fillStyle='#93c5fd'; ctx.fillText('Keep pushing toward your 5K! #CouchTo5K',40,h-50);
        cvs.toBlob(blob=>{
            if(!blob) return;
            const file = new File([blob],'c25k-progress.png',{type:'image/png'});
            if(navigator.canShare && navigator.canShare({files:[file]})){
                navigator.share({files:[file], text:'My Couch to 5K progress!', title:'Couch to 5K'}).catch(()=>{});
            } else {
                const url = URL.createObjectURL(blob); const a=document.createElement('a'); a.href=url; a.download='c25k-progress.png'; a.click(); URL.revokeObjectURL(url);
            }
        },'image/png');
    } catch(e){ alert('Unable to create share image'); }
}

// Map interval type to CSS class
function intervalTypeClass(type){
    if(type==='Run') return 'type-Run';
    if(type==='Walk') return 'type-Walk';
    if(type==='Warmup Walk') return 'type-warmup';
    if(type==='Cooldown Walk') return 'type-cooldown';
    return '';
}

// formatTime now defined earlier