/**
 * @factory/shared/realtime/notification-prefs — the per-type notification
 * EMAIL-channel preference schema + defaults (TASK-0094 R6).
 *
 * IN_APP is ALWAYS on; the per-type pref controls the EMAIL channel only.
 * The product spec (functional-requirements §10, PR-096) requires per-type
 * preferences. The shape:
 *
 *   notificationPrefs: { [NotificationType]: "all" | "instant" | "digest" | "off" }
 *
 * Semantics (the email enqueue decision, recorded in the task file):
 *   - "off"     → no email for this type;
 *   - "digest"  → batch into the 1 h digest;
 *   - "instant" → send now;
 *   - "all"     → treated as "instant" (immediate email) — "all" is the
 *     spec's fourth value; for the EMAIL channel it maps to send-now (there
 *     is no "both immediate AND digest" behavior; recorded).
 *
 * Defaults (recorded): MENTION / ASSIGNMENT = instant; COMMENT /
 * DATABASE_CHANGE = digest; the rest = digest.
 */

import { z } from "zod";

import { NOTIFICATION_TYPES, type NotificationTypeValue } from "./notification-policy.js";

/** The per-type EMAIL-channel modes. */
export const NOTIFICATION_PREF_MODES = ["all", "instant", "digest", "off"] as const;
export type NotificationPrefMode = (typeof NOTIFICATION_PREF_MODES)[number];

/** A user's per-type email prefs (partial — absent types use the default). */
export type NotificationPrefs = Partial<Record<NotificationTypeValue, NotificationPrefMode>>;

/**
 * Zod schema: a (partial) map of NotificationType → pref mode. `z.record`
 * with an enum KEY schema is itself the partial map: any subset of the
 * known types is accepted, and a key outside the enum is stripped (zod v3
 * has no `.partial()` on a record). Absent types → the default on read.
 */
export const NotificationPrefsSchema = z
  .record(z.enum(NOTIFICATION_TYPES), z.enum(NOTIFICATION_PREF_MODES))
  .default({});
export type NotificationPrefsParsed = z.infer<typeof NotificationPrefsSchema>;

/** The per-type defaults (R6). */
export const DEFAULT_NOTIFICATION_PREFS: Record<NotificationTypeValue, NotificationPrefMode> = {
  MENTION: "instant",
  ASSIGNMENT: "instant",
  COMMENT: "digest",
  DATABASE_CHANGE: "digest",
  TASK_ASSIGNED: "digest",
  PAGE_SHARED: "digest",
  AUTOMATION: "digest",
  INTEGRATION: "digest",
  FORM_SUBMITTED: "digest", // Phase 10 (TASK-0108): the owner's digest
  // Confluence expansion (T-157/T-163/T-160): review requests need the
  // reviewer's attention → instant; the rest fold into the digest.
  REVIEW_REQUESTED: "instant",
  APPROVAL_DECISION: "digest",
  WATCH_UPDATE: "digest",
  TASK_DUE: "digest"
};

/**
 * Resolve the effective pref mode for a type given a user's stored prefs
 * (absent → the default). Pure — the API/worker enqueue logic calls this.
 */
export function effectivePrefMode(
  type: NotificationTypeValue,
  prefs: NotificationPrefs,
): NotificationPrefMode {
  return prefs[type] ?? DEFAULT_NOTIFICATION_PREFS[type];
}

/**
 * Whether a type's email should be sent IMMEDIATELY (vs. batched into the
 * digest vs. suppressed). "off" → false (no email at all, the caller checks
 * that separately); "digest" → false; "instant" | "all" → true.
 */
export function prefSendsInstant(type: NotificationTypeValue, prefs: NotificationPrefs): boolean {
  const mode = effectivePrefMode(type, prefs);
  return mode === "instant" || mode === "all";
}

/** Whether a type's email is suppressed entirely ("off"). */
export function prefIsOff(type: NotificationTypeValue, prefs: NotificationPrefs): boolean {
  return effectivePrefMode(type, prefs) === "off";
}

/**
 * Merge a user's STORED (partial, unvalidated — it comes from the
 * `User.notificationPrefs` JSON column) prefs over the per-type defaults,
 * returning the full effective map. Lenient on purpose: a malformed stored
 * value (corruption, a pre-schema row) falls back to the defaults instead of
 * throwing — the prefs endpoint re-validates on write, this is the read path
 * the API `getPrefs` and the worker's email decision both use (one source of
 * truth, so the two never diverge).
 */
export function mergeNotificationPrefs(stored: unknown): NotificationPrefs {
  const parsed = NotificationPrefsSchema.safeParse(stored ?? {});
  const out = { ...DEFAULT_NOTIFICATION_PREFS };
  if (parsed.success) {
    for (const [type, mode] of Object.entries(parsed.data)) {
      out[type as NotificationTypeValue] = mode;
    }
  }
  return out;
}