/* ===== Illustrated Algorithm – Shared Visualization Library ===== */
"use strict";

/* --- Utility --- */
const $ = id => document.getElementById(id);
const $$ = sel => document.querySelectorAll(sel);

/* --- StepController --- */
class StepController {
  constructor(steps, opts = {}) {
    this.steps = steps;
    this.idx = -1;
    this.autoTimer = null;
    this.onRender = opts.onRender || (() => {});
    this.onDone = opts.onDone || (() => {});
    this.autoDelay = opts.autoDelay || 800;
  }
  get current() { return this.idx >= 0 && this.idx < this.steps.length ? this.steps[this.idx] : null; }
  get isEnd() { return this.idx >= this.steps.length - 1; }
  get total() { return this.steps.length; }

  next() {
    if (this.idx < this.steps.length - 1) { this.idx++; this._render(); }
    else this.stopAuto();
  }
  prev() {
    if (this.idx > 0) { this.idx--; this._render(); }
  }
  jumpEnd() {
    this.idx = this.steps.length - 1;
    this._render();
    this.stopAuto();
  }
  jumpTo(i) {
    if (i >= 0 && i < this.steps.length) { this.idx = i; this._render(); }
  }
  reset() {
    this.idx = -1;
    this.stopAuto();
    this._renderPipeline();
    if (this.onRender) this.onRender(null);
  }
  startAuto() {
    this.stopAuto();
    if (this.idx < 0) this.idx = 0;
    this._render();
    this.autoTimer = setInterval(() => {
      if (this.idx < this.steps.length - 1) { this.idx++; this._render(); }
      else { this.stopAuto(); if (this.onDone) this.onDone(); }
    }, this.autoDelay);
  }
  stopAuto() {
    if (this.autoTimer) { clearInterval(this.autoTimer); this.autoTimer = null; }
  }
  _render() {
    if (this.onRender) this.onRender(this.current);
    this._renderPipeline();
  }
  _renderPipeline() {
    const el = $('pipeline');
    if (!el) return;
    el.innerHTML = '';
    for (let i = 0; i < this.steps.length; i++) {
      const d = document.createElement('div');
      d.className = 'step-dot' + (i < this.idx ? ' done' : i === this.idx ? ' active' : '');
      d.title = `Step ${i + 1}`;
      d.style.cursor = 'pointer';
      d.addEventListener('click', () => this.jumpTo(i));
      el.appendChild(d);
    }
  }
}

/* --- Render helpers --- */
function renderArray(container, items, opts = {}) {
  const { barMaxH = 120, barMinW = 28, barGap = 4, classes = [], tags = [], idxLabels = true } = opts;
  const maxVal = Math.max(...items.map(it => typeof it === 'object' ? it.val : it), 1);
  container.innerHTML = '';
  const row = document.createElement('div');
  row.className = 'arr-row';
  items.forEach((item, i) => {
    const val = typeof item === 'object' ? item.val : item;
    const cls = typeof item === 'object' ? (item.cls || '') : (classes[i] || '');
    const tag = typeof item === 'object' ? (item.tag || '') : (tags[i] || '');
    const h = Math.max(8, (val / maxVal) * barMaxH);
    const cell = document.createElement('div');
    cell.className = 'arr-cell';
    cell.innerHTML = `
      <span class="arr-val">${val}</span>
      <div class="arr-bar ${cls}" style="height:${h}px;width:${barMinW}px;"></div>
      ${idxLabels ? `<span class="arr-idx">${i}</span>` : ''}
      ${tag ? `<span class="tag ${cls === 'min-price' || cls === 'best' ? 'tag-green' : cls === 'current' ? 'tag-orange' : cls === 'checking' ? 'tag-blue' : 'tag-orange'}">${tag}</span>` : ''}
    `;
    row.appendChild(cell);
  });
  container.appendChild(row);
}

function renderGrid(container, rows, cols, cellData, opts = {}) {
  /* cellData: 2D array of {val, cls} or null */
  const { cellSize = 48 } = opts;
  container.innerHTML = '';
  const grid = document.createElement('div');
  grid.className = 'grid-vis';
  grid.style.gridTemplateColumns = `repeat(${cols}, ${cellSize}px)`;
  for (let i = 0; i < rows; i++) {
    for (let j = 0; j < cols; j++) {
      const d = cellData && cellData[i] && cellData[i][j] ? cellData[i][j] : { val: '', cls: '' };
      const cell = document.createElement('div');
      cell.className = 'grid-cell ' + (d.cls || '');
      cell.textContent = d.val !== undefined && d.val !== null ? d.val : '';
      grid.appendChild(cell);
    }
  }
  container.appendChild(grid);
}

function renderCode(container, code, highlightLine = -1) {
  container.innerHTML = '';
  const pre = document.createElement('pre');
  pre.className = 'code-block';
  const lines = code.split('\n');
  lines.forEach((line, i) => {
    if (i === highlightLine) {
      const span = document.createElement('span');
      span.className = 'hl';
      span.textContent = line;
      pre.appendChild(span);
    } else {
      pre.appendChild(document.createTextNode(line + '\n'));
    }
  });
  container.appendChild(pre);
}

function renderLinkedList(container, nodes, opts = {}) {
  /* nodes: [{val, cls}] */
  container.innerHTML = '';
  const row = document.createElement('div');
  row.style.cssText = 'display:flex;align-items:center;gap:4px;flex-wrap:wrap;justify-content:center;';
  nodes.forEach((n, i) => {
    const box = document.createElement('div');
    box.style.cssText = `padding:6px 12px;border-radius:6px;font-family:var(--mono);font-size:.85rem;border:2px solid var(--border);background:var(--surface2);transition:all .2s;${n.cls === 'highlight' ? 'border-color:var(--orange);background:var(--orange-dim);' : n.cls === 'done' ? 'border-color:var(--green);background:var(--green-dim);' : ''}`;
    box.textContent = n.val;
    row.appendChild(box);
    if (i < nodes.length - 1) {
      const arrow = document.createElement('span');
      arrow.textContent = '→';
      arrow.style.cssText = 'color:var(--text2);font-size:1.1rem;';
      row.appendChild(arrow);
    }
  });
  container.appendChild(row);
}

function renderBinaryTree(container, tree, opts = {}) {
  /* simple SVG tree rendering */
  container.innerHTML = '';
  if (!tree) return;
  const svg = document.createElementNS('http://www.w3.org/2000/svg', 'svg');
  svg.setAttribute('viewBox', '0 0 500 280');
  svg.style.width = '100%';
  svg.style.maxWidth = '500px';
  const nodeEls = [];
  function draw(node, x, y, spread, depth) {
    if (!node) return;
    const leftSpread = spread / 2;
    if (node.left) {
      const lx = x - leftSpread, ly = y + 60;
      const line = document.createElementNS('http://www.w3.org/2000/svg', 'line');
      line.setAttribute('x1', x); line.setAttribute('y1', y);
      line.setAttribute('x2', lx); line.setAttribute('y2', ly);
      line.setAttribute('stroke', '#2e3347'); line.setAttribute('stroke-width', '2');
      svg.appendChild(line);
      draw(node.left, lx, ly, leftSpread, depth + 1);
    }
    if (node.right) {
      const rx = x + leftSpread, ry = y + 60;
      const line = document.createElementNS('http://www.w3.org/2000/svg', 'line');
      line.setAttribute('x1', x); line.setAttribute('y1', y);
      line.setAttribute('x2', rx); line.setAttribute('y2', ry);
      line.setAttribute('stroke', '#2e3347'); line.setAttribute('stroke-width', '2');
      svg.appendChild(line);
      draw(node.right, rx, ry, leftSpread, depth + 1);
    }
    const g = document.createElementNS('http://www.w3.org/2000/svg', 'g');
    const circle = document.createElementNS('http://www.w3.org/2000/svg', 'circle');
    circle.setAttribute('cx', x); circle.setAttribute('cy', y); circle.setAttribute('r', '18');
    const cls = node.cls || '';
    circle.setAttribute('fill', cls === 'highlight' ? '#f5a623' : cls === 'done' ? '#3dd68c' : '#242836');
    circle.setAttribute('stroke', cls === 'highlight' ? '#f5a623' : cls === 'done' ? '#3dd68c' : '#6c7eff');
    circle.setAttribute('stroke-width', '2');
    const text = document.createElementNS('http://www.w3.org/2000/svg', 'text');
    text.setAttribute('x', x); text.setAttribute('y', y + 5);
    text.setAttribute('text-anchor', 'middle'); text.setAttribute('fill', '#e4e6f0');
    text.setAttribute('font-size', '12'); text.setAttribute('font-family', 'var(--mono)');
    text.textContent = node.val;
    g.appendChild(circle); g.appendChild(text);
    svg.appendChild(g);
  }
  draw(tree, 250, 30, 200, 0);
  container.appendChild(svg);
}

function renderStack(container, items, opts = {}) {
  container.innerHTML = '';
  const stack = document.createElement('div');
  stack.style.cssText = 'display:flex;flex-direction:column-reverse;align-items:center;gap:3px;';
  items.forEach((item, i) => {
    const d = typeof item === 'object' ? item : { val: item, cls: '' };
    const el = document.createElement('div');
    el.style.cssText = `padding:6px 20px;border-radius:4px;font-family:var(--mono);font-size:.82rem;border:1px solid var(--border);background:var(--surface2);min-width:60px;text-align:center;${d.cls === 'top' ? 'border-color:var(--orange);background:var(--orange-dim);' : ''}`;
    el.textContent = d.val;
    stack.appendChild(el);
  });
  container.appendChild(stack);
}

function highlightRange(container, start, end, cls) {
  /* highlight child elements in range [start, end) with class */
  const children = container.children;
  for (let i = 0; i < children.length; i++) {
    if (i >= start && i < end) children[i].classList.add(cls);
    else children[i].classList.remove(cls);
  }
}