/* ============================================================================
   OPPORTUNITIES - view model, status derivation
   ----------------------------------------------------------------------------
   PURE. Strapi access lives in ./opportunities.server.ts.

   Draft section 8 asks for a status tag of Open / Closed, and the listing
   additionally distinguishes a call that has been announced but has not opened
   yet. The status is derived from `openDate` / `deadline` so it cannot go
   stale; `opportunityStatus` in the CMS is required and defaults to
   "upcoming", so it is used as an editorial CLOSE and as the fallback when a
   call carries no dates at all - never as a blanket override, which would let
   a forgotten default hide an open call.
   ========================================================================= */

import {
  formatDate,
  formatFileSize,
  type Locale,
  type TranslationKey,
} from "~/i18n";

import type { CmsFile, CmsImage, CmsRichText } from "../_shared/cms";

/* ---------------------------------------------------------------------------
   TYPES
   ------------------------------------------------------------------------ */

export type OpportunityStatus = "open" | "closed" | "upcoming";

/** The filter tabs: All - Open - Upcoming - Closed. */
export type OpportunityStatusFilter = "all" | OpportunityStatus;

export const OPPORTUNITY_STATUS_FILTERS: readonly OpportunityStatusFilter[] = [
  "all",
  "open",
  "upcoming",
  "closed",
];

export function isOpportunityStatusFilter(
  value: unknown,
): value is OpportunityStatusFilter {
  return (
    typeof value === "string" &&
    (OPPORTUNITY_STATUS_FILTERS as readonly string[]).includes(value)
  );
}

/**
 * `opportunity.opportunityType` in the CMS, verbatim. Only
 * `network-membership` carries behaviour - it is what the "Join the SHARP
 * Network" card links to when the CMS holds such an entry.
 */
export type OpportunityType =
  | "call-eoi"
  | "network-membership"
  | "training"
  | "grant"
  | "other";

export const OPPORTUNITY_TYPES = [
  "call-eoi",
  "network-membership",
  "training",
  "grant",
  "other",
] as const satisfies readonly OpportunityType[];

export interface OpportunityCardData {
  readonly slug: string;
  readonly title: string;
  readonly summary?: string;
  readonly status: OpportunityStatus;
  /** ISO date the call opens - `openDate` in the CMS. */
  readonly openDate?: string;
  /** ISO date applications close. */
  readonly deadline?: string;
  readonly opportunityType?: OpportunityType;
  readonly image?: CmsImage;
}

export interface OpportunityDetailData extends OpportunityCardData {
  readonly documentId: string;
  readonly description?: CmsRichText;
  readonly eligibility?: CmsRichText;
  readonly howToApply?: CmsRichText;
  /** An external application portal. When set, the on-site form is not shown. */
  readonly externalApplicationUrl?: string;
  /** ToR, guidelines, annexes - `attachments` in the CMS. */
  readonly attachments: readonly CmsFile[];
}

/* ---------------------------------------------------------------------------
   STATUS
   ------------------------------------------------------------------------ */

export interface OpportunityWindow {
  readonly openDate?: string | null;
  readonly deadline?: string | null;
  /** `opportunity.opportunityStatus`. Required in the CMS, default "upcoming". */
  readonly status?: OpportunityStatus | null;
}

/** A deadline is inclusive: a call closes at the end of its closing day. */
function endOfDay(value: string): number {
  const date = new Date(value);
  if (Number.isNaN(date.getTime())) return Number.NaN;
  date.setUTCHours(23, 59, 59, 999);
  return date.getTime();
}

/**
 * Precedence, in order:
 *   1. an editorial "closed" - a call can be suspended or closed early, and
 *      that decision must win over a deadline that has not passed yet;
 *   2. the dates, when the entry carries any - they cannot go stale;
 *   3. whatever `opportunityStatus` says, for a call with no dates at all.
 */
export function deriveOpportunityStatus(
  entry: OpportunityWindow,
  now: Date = new Date(),
): OpportunityStatus {
  if (entry.status === "closed") return "closed";

  const at = now.getTime();
  let dated = false;

  if (entry.openDate) {
    const opens = new Date(entry.openDate).getTime();
    if (!Number.isNaN(opens)) {
      dated = true;
      if (at < opens) return "upcoming";
    }
  }

  if (entry.deadline) {
    const closes = endOfDay(entry.deadline);
    if (!Number.isNaN(closes)) {
      dated = true;
      if (at > closes) return "closed";
    }
  }

  return dated ? "open" : (entry.status ?? "open");
}

/** Catalogue key for the Open / Upcoming / Closed badge. */
export function opportunityStatusKey(
  status: OpportunityStatus,
): TranslationKey {
  return status === "open"
    ? "opportunities.statusOpen"
    : status === "upcoming"
      ? "filters.upcoming"
      : "opportunities.statusClosed";
}

/** Label of the card's call to action - only an open call invites an apply. */
export function opportunityActionKey(
  status: OpportunityStatus,
): TranslationKey {
  return status === "open" ? "actions.apply" : "actions.viewDetails";
}

/* ---------------------------------------------------------------------------
   LIST OPERATIONS
   ------------------------------------------------------------------------ */

function deadlineTime(item: OpportunityCardData): number {
  const value = item.deadline ? new Date(item.deadline).getTime() : Number.NaN;
  return Number.isNaN(value) ? Number.POSITIVE_INFINITY : value;
}

const STATUS_ORDER: Readonly<Record<OpportunityStatus, number>> = {
  open: 0,
  upcoming: 1,
  closed: 2,
};

/** Open calls first with the nearest deadline at the top, closed ones last. */
export function sortOpportunities(
  items: readonly OpportunityCardData[],
): OpportunityCardData[] {
  return [...items].sort((a, b) => {
    const byStatus = STATUS_ORDER[a.status] - STATUS_ORDER[b.status];
    if (byStatus !== 0) return byStatus;

    return a.status === "closed"
      ? deadlineTime(b) - deadlineTime(a)
      : deadlineTime(a) - deadlineTime(b);
  });
}

export function filterOpportunities(
  items: readonly OpportunityCardData[],
  status: OpportunityStatusFilter,
): OpportunityCardData[] {
  if (status === "all") return [...items];
  return items.filter((item) => item.status === status);
}

/** The CMS entry the "Join the SHARP Network" card should link to, if any. */
export function findNetworkOpportunity(
  items: readonly OpportunityCardData[],
): OpportunityCardData | undefined {
  return items.find((item) => item.opportunityType === "network-membership");
}

/* ---------------------------------------------------------------------------
   FORMATTING
   ------------------------------------------------------------------------ */

/** "12 March 2026" - a deadline is a calendar day, never a time of day. */
export function formatOpportunityDate(
  value: string | null | undefined,
  locale: Locale,
): string {
  return formatDate(value, locale, { dateStyle: "long", timeZone: "UTC" });
}

/** "PDF · 1.2 MB", or just the type when the upload records no size. */
export function formatAttachmentMeta(file: CmsFile, locale: Locale): string {
  const size =
    file.sizeBytes > 0 ? formatFileSize(file.sizeBytes, locale) : undefined;

  return [file.kind || undefined, size].filter(Boolean).join(" · ");
}