// Timeline (Gantt): bars from a timeline column (or a date column as single days), grouped
// by board group. Drag a bar to move it, drag its right edge to change the end date.
import { html, useState, useRef, useEffect } from '../vendor/preact-htm.mjs';
import { api } from './api.js';
import { navigate, boardPath, mutateBoard } from './store.js';
import { Icon, ymd, parseDate, todayStr, Empty, AvatarStack } from './ui.js';
import * as A from './actions.js';

const DAY = 86400000;
const SCALES = { day: 40, week: 18, month: 6 };

export function TimelineView({ board, view, items }) {
  const boardId = board.board.id;
  const cols = board.columns.filter((c) => c.type === 'timeline' || c.type === 'date');
  const col = cols.find((c) => c.id === view.settings?.column) || cols.find((c) => c.type === 'timeline') || cols[0];
  const people = board.columns.find((c) => c.type === 'people');
  const [scale, setScale] = useState(view.settings?.scale || 'week');
  const scroller = useRef();
  const [drag, setDrag] = useState(null);
  const px = SCALES[scale];
  const today = parseDate(todayStr());
  const range = (it) => {
    const v = it.vals[col?.id];
    if (!v) return null;
    if (col.type === 'date') { const d = parseDate(String(v).slice(0, 10)); return { from: d, to: d }; }
    return { from: parseDate(v.from), to: parseDate(v.to || v.from) };
  };
  const ranges = items.map(range).filter(Boolean);
  const min = new Date(Math.min(today - 14 * DAY, ...ranges.map((r) => r.from))); min.setDate(min.getDate() - 7);
  const max = new Date(Math.max(today.getTime() + 60 * DAY, ...ranges.map((r) => r.to.getTime()))); max.setDate(max.getDate() + 14);
  const days = Math.round((max - min) / DAY);
  const x = (d) => Math.round((d - min) / DAY) * px;
  useEffect(() => { if (scroller.current) scroller.current.scrollLeft = Math.max(0, x(today) - 200); }, [scale, col?.id]);
  if (!col) return html`<${Empty} icon="timeline" title="Timeline needs a timeline or date column"><button class="btn primary" onClick=${() => A.addColumn(boardId, 'timeline')}>Add a timeline column</button><//>`;

  const setting = (patch) => { mutateBoard(boardId, () => { view.settings = { ...view.settings, ...patch }; }); api.patch(`/api/views/${view.id}`, { settings: { ...view.settings, ...patch } }); };

  const startDrag = (e, it, mode) => {
    e.preventDefault(); e.stopPropagation();
    const r = range(it); const x0 = e.clientX;
    let delta = 0;
    const move = (ev) => { delta = Math.round((ev.clientX - x0) / px); setDrag({ id: it.id, mode, delta }); };
    const up = () => {
      window.removeEventListener('pointermove', move); window.removeEventListener('pointerup', up);
      setDrag(null);
      if (!delta) { if (mode === 'move') navigate(boardPath(boardId, { viewId: view.id, itemId: it.id })); return; }
      const shift = (d, n) => { const z = new Date(d); z.setDate(z.getDate() + n); return ymd(z); };
      if (col.type === 'date') A.setValue(boardId, it.id, col.id, shift(r.from, delta));
      else if (mode === 'move') A.setValue(boardId, it.id, col.id, { from: shift(r.from, delta), to: shift(r.to, delta) });
      else { const to = new Date(r.to); to.setDate(to.getDate() + delta); A.setValue(boardId, it.id, col.id, { from: ymd(r.from), to: ymd(to < r.from ? r.from : to) }); }
    };
    window.addEventListener('pointermove', move); window.addEventListener('pointerup', up);
  };

  // Header ticks
  const ticks = [];
  for (let i = 0; i <= days; i++) {
    const d = new Date(min); d.setDate(d.getDate() + i);
    if (scale === 'day' || (scale === 'week' && d.getDay() === 1) || (scale === 'month' && d.getDate() === 1)) ticks.push(d);
  }
  const groups = [...board.groups].sort((a, b) => a.position - b.position);
  return html`<div class="timeline">
    <div class="view-options">
      <div class="seg">${Object.keys(SCALES).map((s) => html`<button key=${s} class=${scale === s ? 'on' : ''} onClick=${() => { setScale(s); setting({ scale: s }); }}>${s[0].toUpperCase() + s.slice(1)}s</button>`)}</div>
      <button class="btn ghost sm" onClick=${() => { scroller.current.scrollLeft = Math.max(0, x(today) - 200); }}>Today</button>
      ${cols.length > 1 ? html`<select class="input sm" value=${col.id} onChange=${(e) => setting({ column: e.target.value })}>${cols.map((c) => html`<option value=${c.id}>${c.title}</option>`)}</select>` : null}
    </div>
    <div class="tl-body">
      <div class="tl-names">
        <div class="tl-corner" />
        ${groups.map((g) => { const gi = items.filter((i) => i.group_id === g.id); return gi.length ? html`<div key=${g.id}>
          <div class="tl-group" style=${{ color: g.color }}>${g.title}</div>
          ${gi.map((it) => html`<div key=${it.id} class="tl-name" onClick=${() => navigate(boardPath(boardId, { viewId: view.id, itemId: it.id }))}>${it.name}</div>`)}</div>` : null; })}
      </div>
      <div class="tl-scroll" ref=${scroller}>
        <div class="tl-canvas" style=${{ width: days * px }}>
          <div class="tl-ticks">${ticks.map((d) => html`<span key=${d.getTime()} style=${{ left: x(d) }}>${scale === 'month' ? d.toLocaleString([], { month: 'short', year: '2-digit' }) : `${d.toLocaleString([], { month: 'short' })} ${d.getDate()}`}</span>`)}</div>
          <div class="tl-today" style=${{ left: x(today) + px / 2 }} />
          ${groups.map((g) => { const gi = items.filter((i) => i.group_id === g.id); return gi.length ? html`<div key=${g.id}>
            <div class="tl-group-row" />
            ${gi.map((it) => {
              const r = range(it);
              let left = r ? x(r.from) : 0; let width = r ? Math.max(px, x(r.to) - x(r.from) + px) : 0;
              if (drag?.id === it.id) { if (drag.mode === 'move') left += drag.delta * px; else width = Math.max(px, width + drag.delta * px); }
              return html`<div key=${it.id} class="tl-row">
                ${r ? html`<div class="tl-item" style=${{ left, width, background: g.color }} onPointerDown=${(e) => startDrag(e, it, 'move')} title=${it.name}>
                  <span class="tl-label">${it.name}</span>${people ? html`<${AvatarStack} ids=${it.vals[people.id] || []} size=${18} max=${2} />` : null}
                  ${col.type === 'timeline' ? html`<span class="tl-resize" onPointerDown=${(e) => startDrag(e, it, 'resize')} />` : null}
                </div>` : html`<button class="tl-set muted small" style=${{ left: x(today) }} onClick=${() => A.setValue(boardId, it.id, col.id, col.type === 'date' ? todayStr() : { from: todayStr(), to: ymd(new Date(today.getTime() + 6 * DAY)) })}>+ Set dates</button>`}
              </div>`;
            })}</div>` : null; })}
        </div>
      </div>
    </div>
  </div>`;
}