import { guardOn, type Guard } from "./types";

export interface TriggerSpec {
  handler: string;
  kind: "every-minutes" | "daily-at-hour";
  value: number;
}

export interface ExistingTrigger {
  id: string;
  handler: string;
}

/**
 * What to create and what to delete so that exactly one trigger exists per
 * desired handler. Running the installer again changes nothing. Apps Script does
 * not expose a clock trigger's interval, so a trigger is matched by its handler.
 */
export function planTriggers(
  existing: ExistingTrigger[],
  desired: TriggerSpec[],
  managedHandlers: string[],
  disabled?: Guard[],
  /** What the last install set up (stored by the adapter). A different cadence means: replace. */
  installed?: TriggerSpec[],
): { create: TriggerSpec[]; remove: string[] } {
  if (!guardOn(disabled, "trigger-dedup")) return { create: [...desired], remove: [] };
  const create: TriggerSpec[] = [];
  const remove: string[] = [];
  for (const d of desired) {
    const mine = existing.filter((t) => t.handler === d.handler);
    const was = installed?.find((i) => i.handler === d.handler);
    const changed = !!was && (was.kind !== d.kind || was.value !== d.value);
    if (!mine.length) create.push(d);
    else if (changed) {
      remove.push(...mine.map((t) => t.id));
      create.push(d);
    } else remove.push(...mine.slice(1).map((t) => t.id));
  }
  for (const t of existing)
    if (managedHandlers.includes(t.handler) && !desired.some((d) => d.handler === t.handler)) remove.push(t.id);
  return { create, remove };
}