"use client";

import { RepeatIcon } from "lucide-react";
import { Field, FieldDescription, FieldError, FieldGroup, FieldLabel } from "@/components/ui/field";
import { Input } from "@/components/ui/input";
import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
import { Switch } from "@/components/ui/switch";
import { Textarea } from "@/components/ui/textarea";
import { ToggleGroup, ToggleGroupItem } from "@/components/ui/toggle-group";
import { CALENDARS, calendarById } from "@/lib/calendars";
import { repeatLabel } from "@/lib/event-display";
import { setCalendar, setStart, type EventForm as EventFormState, type EventFormErrors } from "@/lib/event-form";
import { cn } from "@/lib/utils";

/** Element ids, so the sheet can focus the first field with an error. */
export const fieldId = (field: keyof EventFormState): string => `event-${field}`;

const CALENDAR_ITEMS = CALENDARS.map((c) => ({ value: String(c.id), label: c.label }));

/**
 * The event's fields. Presentational: every rule (end follows start, the
 * birthday recurrence, validation) lives in lib/event-form.ts, and the sheet
 * owns the state.
 *
 * Inputs are the browser's native date/time pickers, which are the good ones
 * on phones. The URL field is plain text with a URL keyboard rather than
 * type="url", whose built-in validation would reject "nachklang.art" before
 * normaliseUrl() could accept it.
 */
export function EventForm({
  form,
  errors,
  disabled,
  onChange,
}: {
  form: EventFormState;
  /** Only the errors to show - empty until the first save attempt. */
  errors: EventFormErrors;
  disabled: boolean;
  onChange: (form: EventFormState) => void;
}) {
  const set = <K extends keyof EventFormState>(key: K, value: EventFormState[K]) => onChange({ ...form, [key]: value });
  const forcedRepeat = calendarById(form.calendarId)?.forcedRepeatFrequency;
  const invalid = (field: keyof EventFormState) => (errors[field] ? true : undefined);

  return (
    <FieldGroup className="gap-5">
      <Field data-invalid={invalid("calendarId")}>
        <FieldLabel htmlFor={fieldId("calendarId")}>Kalender</FieldLabel>
        <Select
          items={CALENDAR_ITEMS}
          value={form.calendarId ? String(form.calendarId) : null}
          onValueChange={(value) => value && onChange(setCalendar(form, Number(value)))}
          disabled={disabled}
        >
          <SelectTrigger id={fieldId("calendarId")} className="w-full" aria-invalid={invalid("calendarId")}>
            <SelectValue placeholder="Kalender wählen" />
          </SelectTrigger>
          <SelectContent>
            {CALENDARS.map((c) => (
              <SelectItem key={c.id} value={String(c.id)}>
                <span aria-hidden className={cn("size-2 rounded-full", c.dotClass)} />
                {c.label}
              </SelectItem>
            ))}
          </SelectContent>
        </Select>
        <FieldError>{errors.calendarId}</FieldError>
      </Field>

      <Field data-invalid={invalid("name")}>
        <FieldLabel htmlFor={fieldId("name")}>Titel</FieldLabel>
        <Input
          id={fieldId("name")}
          value={form.name}
          onChange={(e) => set("name", e.target.value)}
          disabled={disabled}
          aria-invalid={invalid("name")}
          autoComplete="off"
        />
        <FieldError>{errors.name}</FieldError>
      </Field>

      <Field orientation="horizontal">
        <FieldLabel htmlFor={fieldId("wholeDay")} className="font-normal">
          Ganztägig
        </FieldLabel>
        <Switch
          id={fieldId("wholeDay")}
          checked={form.wholeDay}
          onCheckedChange={(checked) => set("wholeDay", checked)}
          disabled={disabled}
        />
      </Field>

      <DateTimeRow
        label="Beginn"
        dateField="startDate"
        timeField="startTime"
        date={form.startDate}
        time={form.startTime}
        showTime={!form.wholeDay}
        errors={errors}
        disabled={disabled}
        onDate={(date) => onChange(setStart(form, date, form.startTime))}
        onTime={(time) => onChange(setStart(form, form.startDate, time))}
      />
      <DateTimeRow
        label="Ende"
        dateField="endDate"
        timeField="endTime"
        date={form.endDate}
        time={form.endTime}
        showTime={!form.wholeDay}
        errors={errors}
        disabled={disabled}
        onDate={(date) => set("endDate", date)}
        onTime={(time) => set("endTime", time)}
      />

      {form.repeatFrequency && (
        <p className="-mt-1 flex items-center gap-2 text-sm text-muted-foreground">
          <RepeatIcon aria-hidden className="size-4 shrink-0" />
          {forcedRepeat
            ? `Wiederholt sich ${repeatLabel(form.repeatFrequency)} – das gilt für alle Termine im Kalender „${calendarById(form.calendarId)?.label}“.`
            : `Wiederholt sich ${repeatLabel(form.repeatFrequency)}.`}
        </p>
      )}

      <Field>
        <FieldLabel htmlFor={fieldId("location")}>Ort</FieldLabel>
        <Input
          id={fieldId("location")}
          value={form.location}
          onChange={(e) => set("location", e.target.value)}
          disabled={disabled}
        />
      </Field>

      <Field data-invalid={invalid("url")}>
        <FieldLabel htmlFor={fieldId("url")}>Link</FieldLabel>
        <Input
          id={fieldId("url")}
          value={form.url}
          onChange={(e) => set("url", e.target.value)}
          disabled={disabled}
          aria-invalid={invalid("url")}
          inputMode="url"
          autoCapitalize="off"
          autoCorrect="off"
          spellCheck={false}
          placeholder="z. B. nachklang.art/konzert"
        />
        <FieldError>{errors.url}</FieldError>
      </Field>

      <Field>
        <FieldLabel htmlFor={fieldId("description")}>Beschreibung</FieldLabel>
        <Textarea
          id={fieldId("description")}
          value={form.description}
          onChange={(e) => set("description", e.target.value)}
          disabled={disabled}
          rows={4}
        />
      </Field>

      <Field>
        <FieldLabel>Status</FieldLabel>
        {form.status === "PRIVATE" ? (
          <FieldDescription>Privat – dieser Status wird beim Speichern beibehalten.</FieldDescription>
        ) : (
          <>
            <ToggleGroup
              value={[form.status]}
              onValueChange={(value) => {
                const next = value[0];
                if (next === "DRAFT" || next === "PUBLIC") set("status", next);
              }}
              variant="outline"
              spacing={0}
              disabled={disabled}
              className="grid w-full grid-cols-2"
              aria-label="Status"
            >
              <ToggleGroupItem value="DRAFT" className="aria-pressed:bg-foreground/[0.06] aria-pressed:font-semibold">
                Entwurf
              </ToggleGroupItem>
              <ToggleGroupItem value="PUBLIC" className="aria-pressed:bg-foreground/[0.06] aria-pressed:font-semibold">
                Veröffentlicht
              </ToggleGroupItem>
            </ToggleGroup>
            <FieldDescription>
              {form.status === "DRAFT"
                ? "Entwürfe sieht nur, wer hier angemeldet ist – nicht in Abos und nicht auf der Website."
                : "Veröffentlichte Termine erscheinen in den Kalender-Abos."}
            </FieldDescription>
          </>
        )}
      </Field>
    </FieldGroup>
  );
}

function DateTimeRow({
  label,
  dateField,
  timeField,
  date,
  time,
  showTime,
  errors,
  disabled,
  onDate,
  onTime,
}: {
  label: string;
  dateField: "startDate" | "endDate";
  timeField: "startTime" | "endTime";
  date: string;
  time: string;
  showTime: boolean;
  errors: EventFormErrors;
  disabled: boolean;
  onDate: (date: string) => void;
  onTime: (time: string) => void;
}) {
  const error = errors[dateField] ?? (showTime ? errors[timeField] : undefined);
  return (
    <Field data-invalid={error ? true : undefined}>
      <FieldLabel htmlFor={fieldId(dateField)}>{label}</FieldLabel>
      <div className="flex gap-2">
        <Input
          id={fieldId(dateField)}
          type="date"
          value={date}
          onChange={(e) => onDate(e.target.value)}
          disabled={disabled}
          aria-invalid={errors[dateField] ? true : undefined}
          className="min-w-0 flex-1"
        />
        {showTime && (
          <Input
            id={fieldId(timeField)}
            type="time"
            value={time}
            onChange={(e) => onTime(e.target.value)}
            disabled={disabled}
            aria-invalid={errors[timeField] ? true : undefined}
            aria-label={`${label} Uhrzeit`}
            className="w-28 shrink-0"
          />
        )}
      </div>
      <FieldError>{error}</FieldError>
    </Field>
  );
}