export type TemporalValidityMode = "current" | "at" | "all";

export type TemporalDataSelection = {
  validityMode: TemporalValidityMode;
  validAt: string | null;
  recordedAt: string | null;
};

export type TemporalContextChangedEventDetail = {
  selection: TemporalDataSelection;
  scopeKey: string;
};

export const PLATFORM_TEMPORAL_CONTEXT_CHANGED_EVENT =
  "govoplan:temporal-context-changed";

export const DEFAULT_TEMPORAL_DATA_SELECTION: TemporalDataSelection = {
  validityMode: "current",
  validAt: null,
  recordedAt: null
};

let activeSelection = DEFAULT_TEMPORAL_DATA_SELECTION;

export function normalizeTemporalDataSelection(
  value: Partial<TemporalDataSelection> | null | undefined
): TemporalDataSelection {
  const validityMode = ["current", "at", "all"].includes(
    String(value?.validityMode)
  )
    ? value?.validityMode as TemporalValidityMode
    : "current";
  const validAt = validityMode === "at"
    ? normalizeTimestamp(value?.validAt)
    : null;
  if (validityMode === "at" && !validAt) {
    throw new Error("i18n:govoplan-core.select_valid_date_time");
  }
  return {
    validityMode,
    validAt,
    recordedAt: normalizeTimestamp(value?.recordedAt)
  };
}

export function temporalDataSelectionIsDefault(
  value: TemporalDataSelection
): boolean {
  return value.validityMode === "current" && !value.recordedAt;
}

export function temporalDataSelectionKey(value: TemporalDataSelection): string {
  return [value.validityMode, value.validAt ?? "", value.recordedAt ?? ""].join(":");
}

export function setActiveTemporalDataSelection(
  value: TemporalDataSelection
): void {
  activeSelection = normalizeTemporalDataSelection(value);
}

export function activeTemporalDataSelection(): TemporalDataSelection {
  return activeSelection;
}

export function temporalRequestHeaders(): Record<string, string> {
  const selection = activeTemporalDataSelection();
  if (temporalDataSelectionIsDefault(selection)) return {};
  const headers: Record<string, string> = {
    "X-Govoplan-Validity-Mode": selection.validityMode
  };
  if (selection.validAt) headers["X-Govoplan-Valid-At"] = selection.validAt;
  if (selection.recordedAt) {
    headers["X-Govoplan-Recorded-At"] = selection.recordedAt;
  }
  return headers;
}

export function dispatchTemporalContextChanged(
  selection: TemporalDataSelection,
  scopeKey: string
): void {
  if (typeof window === "undefined") return;
  window.dispatchEvent(
    new CustomEvent<TemporalContextChangedEventDetail>(
      PLATFORM_TEMPORAL_CONTEXT_CHANGED_EVENT,
      { detail: { selection, scopeKey } }
    )
  );
}

function normalizeTimestamp(value: string | null | undefined): string | null {
  const clean = String(value || "").trim();
  if (!clean) return null;
  const instant = new Date(clean);
  if (!Number.isFinite(instant.getTime())) return null;
  return instant.toISOString();
}