const API = "/api";
let nbId = null, secId = null, pageId = null;
let tool = "pen", paths = [], drawing = false;
let canvas, ctx;

window.onload = function() {
    canvas = document.getElementById("drawing-canvas");
    ctx = canvas.getContext("2d");
    resizeCanvas();
    initDrawing();
    loadNotebooks();
    setInterval(savePage, 30000);
};

function showRibbonTab(tab) {
    document.querySelectorAll(".tab-btn").forEach(b => b.classList.remove("active"));
    document.querySelectorAll(".ribbon-content").forEach(c => c.classList.remove("active"));
    document.querySelector('[data-tab="'+tab+'"]').classList.add("active");
    document.getElementById(tab+"-tab").classList.add("active");
}

function showEditor(type) {
    document.querySelectorAll(".toggle-btn").forEach(b => b.classList.remove("active"));
    document.querySelectorAll(".editor-panel").forEach(p => p.classList.remove("active"));
    document.getElementById("btn-"+type).classList.add("active");
    document.getElementById(type+"-editor").classList.add("active");
    if(type === "draw") setTimeout(resizeCanvas, 100);
}

function formatText(cmd, val) { document.execCommand(cmd, false, val); }

// Insert Table
function insertTable() {
    let html = '<table border="1" style="border-collapse:collapse;width:100%"><tr>';
    for(let i=0; i<3; i++) html += '<td style="padding:8px;border:1px solid #ccc">&nbsp;</td>';
    html += '</tr></table><br>';
    document.execCommand("insertHTML", false, html);
}

// Insert Link
function insertLink() {
    let url = prompt("URL du lien:");
    if(url) document.execCommand("insertHTML", false, '<a href="'+url+'" style="color:#7719AA">'+url+'</a>');
}

// Handle Image
function handleImage(input) {
    if(input.files[0]) {
        let reader = new FileReader();
        reader.onload = e => document.execCommand("insertHTML", false, '<img src="'+e.target.result+'" style="max-width:100%">');
        reader.readAsDataURL(input.files[0]);
    }
}

// Drawing
function setDrawTool(t) {
    tool = t;
    document.querySelectorAll(".tool-btn").forEach(b => b.classList.remove("active"));
    document.getElementById("tool-"+t).classList.add("active");
}

function initDrawing() {
    canvas.onpointerdown = e => { e.preventDefault(); drawing = true; startDraw(e); };
    canvas.onpointermove = e => { if(drawing) moveDraw(e); };
    canvas.onpointerup = () => { drawing = false; savePage(); };
    canvas.ontouchstart = e => { e.preventDefault(); drawing = true; startDraw(e.touches[0]); };
    canvas.ontouchmove = e => { e.preventDefault(); if(drawing) moveDraw(e.touches[0]); };
    canvas.ontouchend = () => { drawing = false; };
    canvas.onmousedown = e => { drawing = true; startDraw(e); };
    canvas.onmousemove = e => { if(drawing) moveDraw(e); };
    canvas.onmouseup = () => { drawing = false; };
}

function resizeCanvas() {
    canvas.width = 2000;
    canvas.height = 2000;
    redraw();
}

function getPos(e) {
    let rect = canvas.getBoundingClientRect();
    return { x: e.clientX - rect.left, y: e.clientY - rect.top, p: e.pressure || 0.5 };
}

function startDraw(e) {
    let pos = getPos(e);
    if(tool === "eraser") erase(pos);
    else {
        let color = document.getElementById("pen-color").value;
        let w = parseInt(document.getElementById("pen-width").value);
        paths.push({ points:[pos], color:tool==="highlighter"?rgba(color,.3):color, width:tool==="highlighter"?w*3:w });
        redraw();
    }
}

function moveDraw(e) {
    let pos = getPos(e);
    if(tool === "eraser") erase(pos);
    else if(paths.length) {
        paths[paths.length-1].points.push(pos);
        redraw();
    }
}

function erase(pos) {
    paths = paths.filter(p => !p.points.some(pt => dist(pt,pos)<20));
    redraw();
}

function dist(a,b) { return Math.sqrt((a.x-b.x)**2+(a.y-b.y)**2); }

function rgba(hex,a) {
    let r=parseInt(hex.slice(1,3),16),g=parseInt(hex.slice(3,5),16),b=parseInt(hex.slice(5,7),16);
    return `rgba(${r},${g},${b},${a})`;
}

function redraw() {
    ctx.clearRect(0,0,canvas.width,canvas.height);
    paths.forEach(p => {
        if(p.points.length<2) return;
        ctx.beginPath(); ctx.lineCap="round"; ctx.strokeStyle=p.color; ctx.lineWidth=p.width;
        ctx.moveTo(p.points[0].x,p.points[0].y);
        p.points.forEach(pt => ctx.lineTo(pt.x,pt.y));
        ctx.stroke();
    });
}

function clearDrawing() { if(confirm("Effacer?")){ paths=[]; redraw(); savePage(); }}

// Zoom
function changeZoom(d) {
    let z = document.getElementById("zoom-level");
    let v = parseInt(z.textContent)+d;
    z.textContent = Math.max(50,Math.min(200,v))+"%";
}

// API
async function loadNotebooks() {
    let res = await fetch(API+"/notebooks");
    let list = document.getElementById("notebook-list");
    list.innerHTML = "";
    (await res.json()).forEach(nb => {
        let li = document.createElement("li");
        li.textContent = nb.name;
        li.style.borderLeft = "3px solid "+nb.color;
        li.onclick = () => selectNotebook(nb.id, li);
        list.appendChild(li);
    });
}

async function selectNotebook(id, el) {
    nbId = id;
    document.querySelectorAll("#notebook-list li").forEach(l => l.classList.remove("selected"));
    el.classList.add("selected");
    let res = await fetch(API+"/notebooks/"+id+"/sections");
    let list = document.getElementById("section-list");
    list.innerHTML = "";
    (await res.json()).forEach(s => {
        let li = document.createElement("li");
        li.textContent = s.name;
        li.onclick = () => selectSection(s.id, li);
        list.appendChild(li);
    });
}

async function selectSection(id, el) {
    secId = id;
    document.querySelectorAll("#section-list li").forEach(l => l.classList.remove("selected"));
    el.classList.add("selected");
    let res = await fetch(API+"/sections/"+id+"/pages");
    let list = document.getElementById("page-list");
    list.innerHTML = "";
    (await res.json()).forEach(p => {
        let li = document.createElement("li");
        li.textContent = p.title;
        li.onclick = () => loadPage(p.id, li);
        list.appendChild(li);
    });
}

async function loadPage(id, el) {
    pageId = id;
    document.querySelectorAll("#page-list li").forEach(l => l.classList.remove("selected"));
    el.classList.add("selected");
    let p = await fetch(API+"/pages/"+id).then(r=>r.json());
    document.getElementById("page-title").value = p.title;
    document.getElementById("rich-editor").innerHTML = p.content || "";
    try { paths = JSON.parse(p.drawing_data||"[]"); } catch(e){ paths=[]; }
    redraw();
}

async function savePage() {
    if(!pageId) return;
    await fetch(API+"/pages/"+pageId, {
        method:"PUT", headers:{"Content-Type":"application/json"},
        body:JSON.stringify({
            title:document.getElementById("page-title").value,
            content:document.getElementById("rich-editor").innerHTML,
            drawing_data:JSON.stringify(paths)
        })
    });
    document.getElementById("status-text").textContent = "Sauvegardé";
}

async function addNotebook() {
    let name = prompt("Nom:");
    if(name) { await fetch(API+"/notebooks", {method:"POST", headers:{"Content-Type":"application/json"}, body:JSON.stringify({name,color:"#7719AA"})}); loadNotebooks(); }
}

async function addSection() {
    if(!nbId) return alert("Sélectionnez un notebook");
    let name = prompt("Nom:");
    if(name) { await fetch(API+"/notebooks/"+nbId+"/sections", {method:"POST", headers:{"Content-Type":"application/json"}, body:JSON.stringify({name})}); selectNotebook(nbId, document.querySelector("#notebook-list li.selected")); }
}

async function addPage() {
    if(!secId) return alert("Sélectionnez une section");
    let title = prompt("Titre:");
    if(title) { await fetch(API+"/sections/"+secId+"/pages", {method:"POST", headers:{"Content-Type":"application/json"}, body:JSON.stringify({title})}); selectSection(secId, document.querySelector("#section-list li.selected")); }
}