/*
 * canvas-crop.js
 * In-place crop tool for cabinet and shelf photos.
 * Renders a draggable crop rectangle on the boundary canvas overlay,
 * then POSTs pixel coordinates to the server to permanently crop the image.
 *
 * Entry point: startCropMode(type, id) — called from events.js 'crop-start'.
 * Disables boundary drag events while active (checked via S._cropMode).
 *
 * Depends on: S (state.js); req, toast (api.js / helpers.js);
 *             drawBnd (canvas-boundary.js) — called in cancelCrop to restore
 *             the boundary overlay after the crop UI is dismissed
 * Provides: startCropMode(), cancelCrop(), confirmCrop()
 */

/* exported startCropMode */

// ── Crop state ───────────────────────────────────────────────────────────────
let _cropState = null; // {x1,y1,x2,y2} fractions; null = not in crop mode
let _cropDragPart = null; // 'tl','tr','bl','br','t','b','l','r','move' | null
let _cropDragStart = null; // {fx,fy,x1,y1,x2,y2} snapshot at drag start

// ── Public entry point ───────────────────────────────────────────────────────
function startCropMode(type, id) {
  const canvas = document.getElementById('bnd-canvas');
  const wrap = document.getElementById('bnd-wrap');
  if (!canvas || !wrap) return;
  S._cropMode = { type, id };
  _cropState = { x1: 0.05, y1: 0.05, x2: 0.95, y2: 0.95 };

  canvas.addEventListener('pointerdown', cropPointerDown);
  canvas.addEventListener('pointermove', cropPointerMove);
  canvas.addEventListener('pointerup', cropPointerUp);

  document.getElementById('crop-bar')?.remove();
  const bar = document.createElement('div');
  bar.id = 'crop-bar';
  bar.style.cssText = 'margin-top:10px;display:flex;gap:8px';
  bar.innerHTML =
    '<button class="btn btn-p" id="crop-ok">Confirm crop</button><button class="btn btn-s" id="crop-cancel">Cancel</button>';
  wrap.after(bar);
  document.getElementById('crop-ok').addEventListener('click', confirmCrop);
  document.getElementById('crop-cancel').addEventListener('click', cancelCrop);

  drawCropOverlay();
}

// ── Drawing ──────────────────────────────────────────────────────────────────
function drawCropOverlay() {
  const canvas = document.getElementById('bnd-canvas');
  if (!canvas || !_cropState) return;
  const ctx = canvas.getContext('2d');
  const W = canvas.width,
    H = canvas.height;
  const { x1, y1, x2, y2 } = _cropState;
  const px1 = x1 * W,
    py1 = y1 * H,
    px2 = x2 * W,
    py2 = y2 * H;

  ctx.clearRect(0, 0, W, H);
  // Dark shadow outside crop rect
  ctx.fillStyle = 'rgba(0,0,0,0.55)';
  ctx.fillRect(0, 0, W, H);
  ctx.clearRect(px1, py1, px2 - px1, py2 - py1);
  // Bright border
  ctx.strokeStyle = '#38bdf8';
  ctx.lineWidth = 2;
  ctx.setLineDash([]);
  ctx.strokeRect(px1, py1, px2 - px1, py2 - py1);
  // Corner handles
  const hs = 9;
  ctx.fillStyle = '#38bdf8';
  [
    [px1, py1],
    [px2, py1],
    [px1, py2],
    [px2, py2],
  ].forEach(([x, y]) => ctx.fillRect(x - hs / 2, y - hs / 2, hs, hs));
}

// ── Hit testing ──────────────────────────────────────────────────────────────
function _cropFracFromEvt(e) {
  const canvas = document.getElementById('bnd-canvas');
  const r = canvas.getBoundingClientRect();
  return { fx: (e.clientX - r.left) / r.width, fy: (e.clientY - r.top) / r.height };
}

function _getCropPart(fx, fy) {
  if (!_cropState) return null;
  const { x1, y1, x2, y2 } = _cropState;
  const th = 0.05;
  const inX = fx >= x1 && fx <= x2,
    inY = fy >= y1 && fy <= y2;
  const nX1 = Math.abs(fx - x1) < th,
    nX2 = Math.abs(fx - x2) < th;
  const nY1 = Math.abs(fy - y1) < th,
    nY2 = Math.abs(fy - y2) < th;
  if (nX1 && nY1) return 'tl';
  if (nX2 && nY1) return 'tr';
  if (nX1 && nY2) return 'bl';
  if (nX2 && nY2) return 'br';
  if (nY1 && inX) return 't';
  if (nY2 && inX) return 'b';
  if (nX1 && inY) return 'l';
  if (nX2 && inY) return 'r';
  if (inX && inY) return 'move';
  return null;
}

function _cropPartCursor(part) {
  if (!part) return 'crosshair';
  if (part === 'move') return 'move';
  if (part === 'tl' || part === 'br') return 'nwse-resize';
  if (part === 'tr' || part === 'bl') return 'nesw-resize';
  if (part === 't' || part === 'b') return 'ns-resize';
  return 'ew-resize';
}

// ── Pointer events ───────────────────────────────────────────────────────────
function cropPointerDown(e) {
  if (!_cropState) return;
  const { fx, fy } = _cropFracFromEvt(e);
  const part = _getCropPart(fx, fy);
  if (part) {
    _cropDragPart = part;
    _cropDragStart = { fx, fy, ..._cropState };
    document.getElementById('bnd-canvas').setPointerCapture(e.pointerId);
  }
}

function cropPointerMove(e) {
  if (!_cropState) return;
  const canvas = document.getElementById('bnd-canvas');
  const { fx, fy } = _cropFracFromEvt(e);
  if (_cropDragPart && _cropDragStart) {
    const dx = fx - _cropDragStart.fx,
      dy = fy - _cropDragStart.fy;
    const s = { ..._cropState };
    if (_cropDragPart === 'move') {
      const w = _cropDragStart.x2 - _cropDragStart.x1,
        h = _cropDragStart.y2 - _cropDragStart.y1;
      s.x1 = Math.max(0, Math.min(1 - w, _cropDragStart.x1 + dx));
      s.y1 = Math.max(0, Math.min(1 - h, _cropDragStart.y1 + dy));
      s.x2 = s.x1 + w;
      s.y2 = s.y1 + h;
    } else {
      if (_cropDragPart.includes('l')) s.x1 = Math.max(0, Math.min(_cropDragStart.x2 - 0.05, _cropDragStart.x1 + dx));
      if (_cropDragPart.includes('r')) s.x2 = Math.min(1, Math.max(_cropDragStart.x1 + 0.05, _cropDragStart.x2 + dx));
      if (_cropDragPart.includes('t')) s.y1 = Math.max(0, Math.min(_cropDragStart.y2 - 0.05, _cropDragStart.y1 + dy));
      if (_cropDragPart.includes('b')) s.y2 = Math.min(1, Math.max(_cropDragStart.y1 + 0.05, _cropDragStart.y2 + dy));
    }
    _cropState = s;
    drawCropOverlay();
    canvas.style.cursor = _cropPartCursor(_cropDragPart);
  } else {
    canvas.style.cursor = _cropPartCursor(_getCropPart(fx, fy));
  }
}

function cropPointerUp() {
  _cropDragPart = null;
  _cropDragStart = null;
}

// ── Confirm / cancel ─────────────────────────────────────────────────────────
async function confirmCrop() {
  if (!_cropState || !S._cropMode) return;
  const img = document.getElementById('bnd-img');
  if (!img) return;
  const { x1, y1, x2, y2 } = _cropState;
  const W = img.naturalWidth,
    H = img.naturalHeight;
  const px = {
    x: Math.round(x1 * W),
    y: Math.round(y1 * H),
    w: Math.round((x2 - x1) * W),
    h: Math.round((y2 - y1) * H),
  };
  if (px.w < 10 || px.h < 10) {
    toast('Selection too small');
    return;
  }
  const { type, id } = S._cropMode;
  const url = type === 'cabinet' ? `/api/cabinets/${id}/crop` : `/api/shelves/${id}/crop`;
  try {
    await req('POST', url, px);
    toast('Cropped');
    cancelCrop();
    render();
  } catch (err) {
    toast('Crop failed: ' + err.message);
  }
}

function cancelCrop() {
  S._cropMode = null;
  _cropState = null;
  _cropDragPart = null;
  _cropDragStart = null;
  document.getElementById('crop-bar')?.remove();
  const canvas = document.getElementById('bnd-canvas');
  if (canvas) {
    canvas.removeEventListener('pointerdown', cropPointerDown);
    canvas.removeEventListener('pointermove', cropPointerMove);
    canvas.removeEventListener('pointerup', cropPointerUp);
    canvas.style.cursor = '';
  }
  drawBnd(); // restore boundary overlay
}