"use client";

/** 发帖截止时间：快捷天数 + 自定义时刻 */

export type DeadlineMode = "preset" | "custom";

function pad2(n: number) {
  return String(n).padStart(2, "0");
}

/** datetime-local 值（本地时区） */
export function toLocalInputValue(d: Date): string {
  return `${d.getFullYear()}-${pad2(d.getMonth() + 1)}-${pad2(d.getDate())}T${pad2(d.getHours())}:${pad2(d.getMinutes())}`;
}

/** 默认自定义：从现在起 +N 天 */
export function defaultCustomLocal(days = 7): string {
  const d = new Date();
  d.setDate(d.getDate() + days);
  d.setSeconds(0, 0);
  return toLocalInputValue(d);
}

/** 本地 datetime-local → RFC3339（UTC） */
export function localInputToRFC3339(local: string): string | null {
  const t = Date.parse(local);
  if (!Number.isFinite(t)) return null;
  return new Date(t).toISOString().replace(/\.\d{3}Z$/, "Z");
}

export function formatLocalPreview(local: string): string {
  const t = Date.parse(local);
  if (!Number.isFinite(t)) return "";
  try {
    return new Date(t).toLocaleString("zh-CN");
  } catch {
    return local;
  }
}

export default function DeadlinePicker({
  label = "截止时间",
  presets,
  mode,
  onModeChange,
  days,
  onDaysChange,
  customLocal,
  onCustomLocalChange,
  disabled,
  hint,
}: {
  label?: string;
  presets: readonly number[];
  mode: DeadlineMode;
  onModeChange: (m: DeadlineMode) => void;
  days: number;
  onDaysChange: (d: number) => void;
  customLocal: string;
  onCustomLocalChange: (v: string) => void;
  disabled?: boolean;
  hint?: string;
}) {
  const minLocal = toLocalInputValue(new Date(Date.now() + 60 * 60 * 1000));
  const maxLocal = toLocalInputValue(new Date(Date.now() + 90 * 24 * 60 * 60 * 1000));

  return (
    <div className="j13-deadline-picker">
      <div className="j13-deadline-picker-label">{label}</div>
      <div className="j13-deadline-picker-modes" role="tablist" aria-label={label}>
        <button
          type="button"
          role="tab"
          aria-selected={mode === "preset"}
          className={`j13-deadline-mode${mode === "preset" ? " is-on" : ""}`}
          disabled={disabled}
          onClick={() => onModeChange("preset")}
        >
          快捷时长
        </button>
        <button
          type="button"
          role="tab"
          aria-selected={mode === "custom"}
          className={`j13-deadline-mode${mode === "custom" ? " is-on" : ""}`}
          disabled={disabled}
          onClick={() => {
            onModeChange("custom");
            if (!customLocal) onCustomLocalChange(defaultCustomLocal(days || 7));
          }}
        >
          指定时刻
        </button>
      </div>

      {mode === "preset" ? (
        <div className="j13-deadline-presets">
          {presets.map((d) => (
            <button
              key={d}
              type="button"
              className={`btn btn-sm ${days === d ? "btn-primary" : "btn-line"}`}
              disabled={disabled}
              onClick={() => onDaysChange(d)}
            >
              {d} 天
            </button>
          ))}
        </div>
      ) : (
        <div className="j13-deadline-custom">
          <input
            type="datetime-local"
            className="j13-compose-field j13-deadline-datetime"
            value={customLocal}
            min={minLocal}
            max={maxLocal}
            disabled={disabled}
            onChange={(e) => onCustomLocalChange(e.target.value)}
            aria-label="指定截止时刻"
          />
          {customLocal ? (
            <p className="meta text-[12.5px] !mb-0">将于 {formatLocalPreview(customLocal)} 截止</p>
          ) : null}
        </div>
      )}
      {hint ? <p className="meta text-[12px] !mb-0">{hint}</p> : null}
    </div>
  );
}