ihasmail/web/src/views/calendar/CalendarView.tsx

import { useCallback, useEffect, useMemo, useRef, useState } from "react";
import { useLocation } from "wouter";
import { ChevronLeft, ChevronRight, Plus, Calendar as CalIcon } from "lucide-react";
import { useCalendar, participantAddresses, type EventInstance } from "@/store/calendar";
import { useSettings } from "@/store/settings";
import { addDays, addMonths, DAY_MS, endOfDay, isSameDay, isToday, monthGrid, roundToNext, startOfDay, startOfWeek, toLocalDateOnly, weekDays } from "@/lib/dates";
import { formatMonthYear, formatTime } from "@/lib/format";
import { formatDate, formatDateLong, formatDayMonth, formatHourLabel, formatWeekday, formatWeekdayDate } from "@/lib/datetime";
import { Empty, useIsMobile } from "@/ui/misc";
import { keyboard } from "@/lib/keyboard";
import { EventPopover } from "./EventPopover";
import { EventEditor, type EditorInit } from "./EventEditor";
import type { Anchor } from "@/ui/popover";
import { CalendarContextMenu, eventColor, type CalendarContext } from "./CalendarContextMenu";

type View = "month" | "week" | "day" | "agenda";
const HOUR_H = 48;

export function CalendarView({ view: viewParam, date }: { view?: string; date?: string }) {
  const [, navigate] = useLocation();
  const cal = useCalendar();
  const settings = useSettings((s) => s.settings);
  const isMobile = useIsMobile();
  const view: View = (["month", "week", "day", "agenda"].includes(viewParam ?? "") ? viewParam : settings.calendarDefaultView) as View;
  const anchor = useMemo(() => {
    const d = date ? new Date(`${date}T00:00:00`) : new Date();
    return Number.isNaN(d.getTime()) ? startOfDay(new Date()) : startOfDay(d);
  }, [date]);
  const [popover, setPopover] = useState<{ inst: EventInstance; anchor: Anchor } | null>(null);
  const [editor, setEditor] = useState<EditorInit | null>(null);
  const [ctx, setCtx] = useState<CalendarContext | null>(null);
  const weekStart = settings.weekStart;
  const effectiveView: View = isMobile && view === "week" ? "day" : view;

  // Range to load
  const range = useMemo(() => {
    if (effectiveView === "month") {
      const g = monthGrid(anchor, weekStart);
      return { start: g[0]!, end: addDays(g[41]!, 1) };
    }
    if (effectiveView === "week") {
      const s = startOfWeek(anchor, weekStart);
      return { start: s, end: addDays(s, 7) };
    }
    if (effectiveView === "day") return { start: anchor, end: addDays(anchor, 1) };
    return { start: anchor, end: addDays(anchor, 60) };
  }, [effectiveView, anchor, weekStart]);

  useEffect(() => {
    if (cal.available) void cal.loadRange(range.start, range.end);
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [cal.available, range.start.getTime(), range.end.getTime()]);

  const go = useCallback((v: View, d: Date) => navigate(`/calendar/${v}/${toLocalDateOnly(d)}`), [navigate]);
  const step = (n: number) => {
    if (effectiveView === "month") go(view, addMonths(anchor, n));
    else if (effectiveView === "week") go(view, addDays(anchor, 7 * n));
    else if (effectiveView === "day") go(view, addDays(anchor, n));
    else go(view, addDays(anchor, 30 * n));
  };

  const openNew = useCallback(
    (start?: Date, end?: Date, allDay = false) => {
      const s = start ?? roundToNext(new Date(), 30);
      const e = end ?? new Date(s.getTime() + settings.defaultEventDuration * 60_000);
      setEditor({ start: s, end: e, allDay });
    },
    [settings.defaultEventDuration],
  );

  useEffect(() => {
    const onNew = () => openNew();
    window.addEventListener("ihm:new-event", onNew);
    return () => window.removeEventListener("ihm:new-event", onNew);
  }, [openNew]);

  useEffect(
    () =>
      keyboard.pushScope("calendar", [
        { keys: "t", description: "Today", group: "Calendar", handler: () => go(view, new Date()) },
        { keys: "n", description: "Next period", group: "Calendar", handler: () => step(1) },
        { keys: "p", description: "Previous period", group: "Calendar", handler: () => step(-1) },
        { keys: "d", description: "Day view", group: "Calendar", handler: () => go("day", anchor) },
        { keys: "w", description: "Week view", group: "Calendar", handler: () => go("week", anchor) },
        { keys: "m", description: "Month view", group: "Calendar", handler: () => go("month", anchor) },
        { keys: "a", description: "Agenda view", group: "Calendar", handler: () => go("agenda", anchor) },
        { keys: "c", description: "New event", group: "Calendar", handler: () => openNew() },
      ]),
    // eslint-disable-next-line react-hooks/exhaustive-deps
    [view, anchor, openNew],
  );

  if (!cal.available) {
    return <div className="p-16"><Empty icon={<CalIcon size={40} />} title="Calendar is not available">This account does not have the JMAP calendars capability.</Empty></div>;
  }

  const title =
    effectiveView === "month" ? formatMonthYear(anchor)
    : effectiveView === "week" ? `${formatDayMonth(range.start)} – ${formatDate(addDays(range.end, -1))}`
    : effectiveView === "day" ? formatWeekdayDate(anchor, true)
    : `Agenda from ${formatDayMonth(anchor)}`;

  const onEvent = (inst: EventInstance, el: Element) => {
    const r = el.getBoundingClientRect();
    setPopover({ inst, anchor: { x: r.left, y: r.top, w: r.width, h: r.height } });
  };
  const onEventContext = (inst: EventInstance, e: React.MouseEvent) => {
    e.preventDefault();
    e.stopPropagation();
    setPopover(null);
    setCtx({ kind: "event", inst, anchor: { x: e.clientX, y: e.clientY, w: 0, h: 0 } });
  };
  const onSlotContext = (start: Date, end: Date, allDay: boolean, e: React.MouseEvent) => {
    e.preventDefault();
    setCtx({ kind: "slot", start, end, allDay, anchor: { x: e.clientX, y: e.clientY, w: 0, h: 0 } });
  };

  return (
    <div className="cal-main">
      <div className="cal-toolbar">
        <button className="btn btn-sm" onClick={() => go(view, new Date())}>Today</button>
        <button className="icon-btn sm" onClick={() => step(-1)} aria-label="Previous"><ChevronLeft size={18} /></button>
        <button className="icon-btn sm" onClick={() => step(1)} aria-label="Next"><ChevronRight size={18} /></button>
        <h2 className="truncate">{title}</h2>
        <span className="spacer" />
        {cal.loading && <span className="spinner" />}
        <div className="view-switch">
          {(["day", "week", "month", "agenda"] as View[]).filter((v) => !(isMobile && v === "week")).map((v) => (
            <button key={v} className={effectiveView === v ? "active" : ""} onClick={() => go(v, anchor)}>{v[0]!.toUpperCase() + v.slice(1)}</button>
          ))}
        </div>
        {!isMobile && <button className="btn btn-primary btn-sm" onClick={() => openNew()}><Plus size={16} /> Event</button>}
      </div>
      {cal.error && <div className="error-box" style={{ margin: 12 }}>{cal.error}</div>}
      {effectiveView === "month" && <MonthView anchor={anchor} weekStart={weekStart} onDay={(d) => go("day", d)} onEvent={onEvent} onEventContext={onEventContext} onSlotContext={onSlotContext} onCreate={(d) => openNew(new Date(d.getTime() + 9 * 3600_000))} />}
      {(effectiveView === "week" || effectiveView === "day") && <TimeGrid days={effectiveView === "week" ? weekDays(anchor, weekStart) : [anchor]} onEvent={onEvent} onEventContext={onEventContext} onSlotContext={onSlotContext} onCreate={(s, e, allDay) => openNew(s, e, allDay)} onDayHeader={(d) => go("day", d)} workStart={settings.workDayStart} workEnd={settings.workDayEnd} />}
      {effectiveView === "agenda" && <AgendaView start={anchor} onEvent={onEvent} onEventContext={onEventContext} />}
      {ctx && <CalendarContextMenu ctx={ctx} onClose={() => setCtx(null)} onOpen={(inst, a) => setPopover({ inst, anchor: a })} onEdit={(inst) => setEditor({ event: inst.event, start: inst.start, end: inst.end, allDay: inst.allDay })} onCreate={(s, e, allDay) => { setCtx(null); openNew(s, e, allDay); }} />}
      {isMobile && <button className="fab" aria-label="New event" onClick={() => openNew()}><Plus size={24} /></button>}
      {popover && <EventPopover inst={popover.inst} anchor={popover.anchor} onClose={() => setPopover(null)} onEdit={() => { setEditor({ event: popover.inst.event, start: popover.inst.start, end: popover.inst.end, allDay: popover.inst.allDay }); setPopover(null); }} />}
      {editor && <EventEditor init={editor} onClose={() => setEditor(null)} />}
    </div>
  );
}

/* ---------------- Month ---------------- */

type EvCtx = (i: EventInstance, e: React.MouseEvent) => void;
type SlotCtx = (start: Date, end: Date, allDay: boolean, e: React.MouseEvent) => void;

function MonthView({ anchor, weekStart, onDay, onEvent, onEventContext, onSlotContext, onCreate }: { anchor: Date; weekStart: number; onDay: (d: Date) => void; onEvent: (i: EventInstance, el: Element) => void; onEventContext: EvCtx; onSlotContext: SlotCtx; onCreate: (d: Date) => void }) {
  const cal = useCalendar();
  const grid = useMemo(() => monthGrid(anchor, weekStart), [anchor, weekStart]);
  const instances = cal.instancesIn(grid[0]!, addDays(grid[41]!, 1));
  const weeks = [...Array(6)].map((_, w) => grid.slice(w * 7, w * 7 + 7));
  const dow = weeks[0]!.map((d) => formatWeekday(d));
  const maxPer = 4;
  return (
    <div className="month-grid">
      <div className="dow-row">{dow.map((d) => <div key={d}>{d}</div>)}</div>
      {weeks.map((days, wi) => (
        <div key={wi} className="week-row">
          {days.map((d) => {
            const dayEnd = addDays(d, 1);
            const evs = instances.filter((i) => i.start < dayEnd && i.end > d);
            const shown = evs.slice(0, maxPer);
            return (
              <div key={d.toISOString()} className={`month-cell ${d.getMonth() !== anchor.getMonth() ? "other" : ""} ${isToday(d) ? "today" : ""}`} onClick={() => onCreate(d)} onDoubleClick={() => onDay(d)} onContextMenu={(e) => onSlotContext(new Date(d.getTime() + 9 * 3600_000), new Date(d.getTime() + 10 * 3600_000), false, e)}>
                <span className="day-num" onClick={(e) => { e.stopPropagation(); onDay(d); }}>{d.getDate() === 1 ? formatDayMonth(d) : d.getDate()}</span>
                {shown.map((i) => <EventChip key={i.key} inst={i} day={d} onClick={(el) => onEvent(i, el)} onContext={(e) => onEventContext(i, e)} />)}
                {evs.length > maxPer && <span className="more" onClick={(e) => { e.stopPropagation(); onDay(d); }}>+{evs.length - maxPer} more</span>}
              </div>
            );
          })}
        </div>
      ))}
    </div>
  );
}

function statusClass(i: EventInstance): string {
  const ev = i.event;
  const mine = useCalendar.getState().identities;
  const ids = mine.flatMap((m) => [m.calendarAddress.toLowerCase(), ...Object.values(m.sendTo ?? {}).map((x) => x.toLowerCase())]);
  let my: string | undefined;
  for (const p of Object.values(ev.participants ?? {})) {
    if (participantAddresses(p).some((a) => ids.includes(a))) my = p.participationStatus;
  }
  if (ev.status === "cancelled") return "cancelled";
  if (my === "declined") return "declined";
  if (my === "tentative" || my === "needs-action" || ev.status === "tentative") return "tentative";
  return "";
}

function useEventColor() {
  const categories = useSettings((s) => s.settings.eventCategories);
  return (inst: EventInstance) => eventColor(inst.event, inst.calendar?.color, categories);
}

function EventChip({ inst, day, onClick, onContext }: { inst: EventInstance; day: Date; onClick: (el: Element) => void; onContext?: (e: React.MouseEvent) => void }) {
  const color = useEventColor()(inst);
  const spansDay = inst.allDay || inst.end.getTime() - inst.start.getTime() >= DAY_MS || !isSameDay(inst.start, inst.end) && inst.start < day;
  return (
    <div className={`ev-chip ${spansDay ? "" : "timed"} ${statusClass(inst)}`} style={{ background: color, borderColor: color }} onClick={(e) => { e.stopPropagation(); onClick(e.currentTarget); }} onContextMenu={onContext} title={inst.event.title ?? ""}>
      {!spansDay && <span className="ev-dot" style={{ background: color }} />}
      {!spansDay && <span className="ev-time">{formatTime(inst.start)}</span>}
      <span className="truncate">{inst.event.title || "(untitled)"}</span>
    </div>
  );
}

/* ---------------- Week / Day ---------------- */

function TimeGrid({ days, onEvent, onEventContext, onSlotContext, onCreate, onDayHeader, workStart, workEnd }: { days: Date[]; onEvent: (i: EventInstance, el: Element) => void; onEventContext: EvCtx; onSlotContext: SlotCtx; onCreate: (s: Date, e: Date, allDay: boolean) => void; onDayHeader: (d: Date) => void; workStart: number; workEnd: number }) {
  const cal = useCalendar();
  const colorOf = useEventColor();
  const scrollRef = useRef<HTMLDivElement>(null);
  const start = days[0]!;
  const end = addDays(days[days.length - 1]!, 1);
  const instances = cal.instancesIn(start, end);
  const [now, setNow] = useState(new Date());
  const [drag, setDrag] = useState<{ day: Date; startMin: number; endMin: number } | null>(null);
  useEffect(() => {
    const t = window.setInterval(() => setNow(new Date()), 60_000);
    return () => window.clearInterval(t);
  }, []);
  useEffect(() => {
    // scroll to 7am-ish on mount
    if (scrollRef.current) scrollRef.current.scrollTop = Math.max(0, (Math.min(workStart, 8) - 0.5) * HOUR_H);
  }, [workStart, days.length]);

  const allDay = (d: Date) => instances.filter((i) => (i.allDay || i.end.getTime() - i.start.getTime() >= DAY_MS) && i.start < addDays(d, 1) && i.end > d);
  const timed = (d: Date) => instances.filter((i) => !(i.allDay || i.end.getTime() - i.start.getTime() >= DAY_MS) && i.start < addDays(d, 1) && i.end > d);

  const minutesFromEvent = (e: React.MouseEvent, col: HTMLElement) => {
    const r = col.getBoundingClientRect();
    const y = e.clientY - r.top + 0; // col is full height
    return Math.max(0, Math.min(24 * 60, Math.round((y / HOUR_H) * 60 / 15) * 15));
  };

  return (
    <div className="week-view" style={{ "--cols": days.length } as React.CSSProperties}>
      <div className="week-head">
        <div />
        {days.map((d) => (
          <div key={d.toISOString()} className={`wh-day ${isToday(d) ? "today" : ""}`} onClick={() => onDayHeader(d)}>
            <div className="dow">{formatWeekday(d)}</div>
            <div className="dnum">{d.getDate()}</div>
          </div>
        ))}
      </div>
      <div className="week-allday">
        <div className="ad-label">all-day</div>
        {days.map((d) => (
          <div key={d.toISOString()} className="ad-cell" onClick={() => onCreate(d, addDays(d, 1), true)} onContextMenu={(e) => onSlotContext(d, addDays(d, 1), true, e)}>
            {allDay(d).map((i) => <EventChip key={i.key} inst={i} day={d} onClick={(el) => onEvent(i, el)} onContext={(e) => onEventContext(i, e)} />)}
          </div>
        ))}
      </div>
      <div className="week-scroll" ref={scrollRef}>
        <div className="week-body" style={{ "--hour-h": `${HOUR_H}px` } as React.CSSProperties}>
          <div className="time-col">
            {[...Array(24)].map((_, h) => h > 0 && <span key={h} className="hour-label" style={{ top: h * HOUR_H }}>{formatHourLabel(h)}</span>)}
          </div>
          {days.map((d) => {
            const evs = layoutOverlaps(timed(d), d);
            const today = isToday(d);
            const nowTop = ((now.getHours() * 60 + now.getMinutes()) / 60) * HOUR_H;
            return (
              <div
                key={d.toISOString()}
                className={`day-col ${today ? "today" : ""}`}
                onMouseDown={(e) => {
                  if (e.button !== 0) return;
                  if ((e.target as HTMLElement).closest(".ev-block")) return;
                  const m = minutesFromEvent(e, e.currentTarget);
                  setDrag({ day: d, startMin: m, endMin: m + 30 });
                }}
                onMouseMove={(e) => {
                  if (!drag || !isSameDay(drag.day, d)) return;
                  const m = minutesFromEvent(e, e.currentTarget);
                  setDrag({ ...drag, endMin: Math.max(drag.startMin + 15, m) });
                }}
                onMouseUp={() => {
                  if (!drag || !isSameDay(drag.day, d)) return;
                  const s = new Date(d.getTime() + drag.startMin * 60_000);
                  const e2 = new Date(d.getTime() + drag.endMin * 60_000);
                  setDrag(null);
                  onCreate(s, e2, false);
                }}
                onMouseLeave={() => { if (drag && isSameDay(drag.day, d)) { const s = new Date(d.getTime() + drag.startMin * 60_000); const e2 = new Date(d.getTime() + drag.endMin * 60_000); setDrag(null); onCreate(s, e2, false); } }}
                onContextMenu={(e) => {
                  if ((e.target as HTMLElement).closest(".ev-block")) return;
                  const m = minutesFromEvent(e, e.currentTarget);
                  const st = new Date(d.getTime() + Math.floor(m / 30) * 30 * 60_000);
                  onSlotContext(st, new Date(st.getTime() + 60 * 60_000), false, e);
                }}
              >
                <div className="work-hours" style={{ top: workStart * HOUR_H, height: Math.max(0, workEnd - workStart) * HOUR_H }} />
                {[...Array(24)].map((_, h) => <div key={h} className="hour-line" style={{ top: h * HOUR_H }} />)}
                {[...Array(24)].map((_, h) => <div key={`h${h}`} className="half-line" style={{ top: h * HOUR_H + HOUR_H / 2 }} />)}
                {today && <div className="now-line" style={{ top: nowTop }} />}
                {evs.map(({ inst, top, height, left, width }) => {
                  const color = colorOf(inst);
                  return (
                    <div key={inst.key} className={`ev-block ${statusClass(inst)}`} style={{ top, height: Math.max(height, 18), left: `${left}%`, width: `calc(${width}% - 3px)`, background: color }} onClick={(e) => { e.stopPropagation(); onEvent(inst, e.currentTarget); }} onContextMenu={(e) => onEventContext(inst, e)} title={inst.event.title ?? ""}>
                      <div className="ev-title">{inst.event.title || "(untitled)"}</div>
                      {height > 30 && <div className="ev-time">{formatTime(inst.start)} – {formatTime(inst.end)}</div>}
                    </div>
                  );
                })}
                {drag && isSameDay(drag.day, d) && (
                  <div className="ev-block draft-new" style={{ top: (drag.startMin / 60) * HOUR_H, height: ((drag.endMin - drag.startMin) / 60) * HOUR_H, left: 0, width: "calc(100% - 3px)", background: "var(--accent)" }}>
                    <div className="ev-title">(new event)</div>
                    <div className="ev-time">{formatTime(new Date(d.getTime() + drag.startMin * 60_000))} – {formatTime(new Date(d.getTime() + drag.endMin * 60_000))}</div>
                  </div>
                )}
              </div>
            );
          })}
        </div>
      </div>
    </div>
  );
}

/** Simple column layout for overlapping events. */
function layoutOverlaps(evs: EventInstance[], day: Date): Array<{ inst: EventInstance; top: number; height: number; left: number; width: number }> {
  const dayStart = day.getTime();
  const dayEnd = dayStart + DAY_MS;
  const items = evs
    .map((inst) => {
      const s = Math.max(inst.start.getTime(), dayStart);
      const e = Math.min(inst.end.getTime(), dayEnd);
      return { inst, s, e, col: 0, cols: 1 };
    })
    .sort((a, b) => a.s - b.s || b.e - a.e);
  // Greedy column assignment within clusters
  const clusters: Array<typeof items> = [];
  let cur: typeof items = [];
  let curEnd = -1;
  for (const it of items) {
    if (cur.length && it.s >= curEnd) {
      clusters.push(cur);
      cur = [];
      curEnd = -1;
    }
    cur.push(it);
    curEnd = Math.max(curEnd, it.e);
  }
  if (cur.length) clusters.push(cur);
  for (const cl of clusters) {
    const colEnds: number[] = [];
    for (const it of cl) {
      let c = colEnds.findIndex((end) => end <= it.s);
      if (c < 0) {
        c = colEnds.length;
        colEnds.push(0);
      }
      colEnds[c] = it.e;
      it.col = c;
    }
    for (const it of cl) it.cols = colEnds.length;
  }
  return items.map((it) => ({
    inst: it.inst,
    top: ((it.s - dayStart) / 3_600_000) * HOUR_H,
    height: ((it.e - it.s) / 3_600_000) * HOUR_H,
    left: (it.col / it.cols) * 100,
    width: 100 / it.cols,
  }));
}

/* ---------------- Agenda ---------------- */

function AgendaView({ start, onEvent, onEventContext }: { start: Date; onEvent: (i: EventInstance, el: Element) => void; onEventContext: EvCtx }) {
  const cal = useCalendar();
  const colorOf = useEventColor();
  const end = addDays(start, 60);
  const instances = cal.instancesIn(start, end);
  const byDay = useMemo(() => {
    const map = new Map<string, { day: Date; items: EventInstance[] }>();
    for (const i of instances) {
      let d = startOfDay(i.start < start ? start : i.start);
      const last = startOfDay(new Date(i.end.getTime() - 1));
      while (d <= last && d < end) {
        const k = toLocalDateOnly(d);
        const e = map.get(k) ?? { day: new Date(d), items: [] };
        e.items.push(i);
        map.set(k, e);
        d = addDays(d, 1);
        if (!i.allDay && isSameDay(i.start, i.end)) break;
      }
    }
    return [...map.values()].sort((a, b) => a.day.getTime() - b.day.getTime());
  }, [instances, start, end]);
  if (!byDay.length) return <Empty icon={<CalIcon size={36} />} title="Nothing scheduled">No events in the next 60 days.</Empty>;
  return (
    <div className="agenda">
      {byDay.map(({ day, items }) => (
        <div key={day.toISOString()} className="agenda-day">
          <div className={`ad-date ${isToday(day) ? "today" : ""}`}>
            {formatWeekday(day, "long")}
            <small>{formatDateLong(day, false)}</small>
          </div>
          <div>
            {items.map((i) => (
              <div key={i.key + day.toISOString()} className={`agenda-ev ${statusClass(i)}`} onClick={(e) => onEvent(i, e.currentTarget)} onContextMenu={(e) => onEventContext(i, e)}>
                <span className="ev-dot" style={{ background: colorOf(i) }} />
                <span className="ev-when">{i.allDay ? "All day" : `${formatTime(i.start)} – ${formatTime(i.end)}`}</span>
                <span className="grow truncate">{i.event.title || "(untitled)"}</span>
                {Object.values(i.event.locations ?? {})[0]?.name && <span className="hint truncate" style={{ maxWidth: 200 }}>{Object.values(i.event.locations ?? {})[0]!.name}</span>}
              </div>
            ))}
          </div>
        </div>
      ))}
    </div>
  );
}

export { endOfDay };