/**
 * The card model: everything one social image renders, and nothing else.
 *
 * This object is the hash input for the manifest, so it must be derived purely from
 * API data plus the day the build runs on. Two rules follow from that:
 *
 *   - No relative times finer than a day. "3 minutes ago" in a static PNG is a lie by
 *     the time anyone sees it; day counts and month/year stamps go stale slowly enough
 *     to survive until the next scheduled rebuild regenerates them.
 *   - Everything the template touches is in the model, and the template touches
 *     nothing but the model. A design change is a TEMPLATE_VERSION bump, which busts
 *     every hash at once; a data change busts exactly the mints it happened to.
 *
 * The warning logic is imported from shared/, not restated: the image must never
 * disagree with the page it decorates about whether a mint is frozen or gone.
 */
import { getMintWarnings, parseLimits, readCapabilities } from '@cashumints/shared';

/** Bump when the template's layout or copy changes, to regenerate every image. */
export const TEMPLATE_VERSION = 1;

const DAY = 86_400;

/** English month/year ("Mar 2026") — the images are one English render for all locales. */
export function monthYear(unix) {
  return new Date(unix * 1000).toLocaleDateString('en-GB', {
    month: 'short',
    year: 'numeric',
    timeZone: 'UTC',
  });
}

/** "3 Aug 2026", matching f.date() on the pages. */
export function shortDate(unix) {
  return new Date(unix * 1000).toLocaleDateString('en-GB', {
    day: 'numeric',
    month: 'short',
    year: 'numeric',
    timeZone: 'UTC',
  });
}

/* ---- mirrors of web/src/lib/format.ts, which is TypeScript this script cannot load.
   Same algorithms, asserted by eyeball against the site's own fallback tiles. ---- */

export function displayDomain(url) {
  return url.replace(/^https?:\/\//, '').replace(/\/+$/, '');
}

/** The site's deterministic gradient, resolved to hex pairs satori understands. */
export function iconGradient(seed) {
  let hash = 0;
  for (let i = 0; i < seed.length; i++) hash = (hash * 31 + seed.charCodeAt(i)) >>> 0;
  const hue = hash % 360;
  const hue2 = (hue + 40) % 360;
  return [hsl(hue, 45, 55), hsl(hue2, 45, 45)];
}

function hsl(h, s, l) {
  s /= 100;
  l /= 100;
  const k = (n) => (n + h / 30) % 12;
  const a = s * Math.min(l, 1 - l);
  const f = (n) => l - a * Math.max(-1, Math.min(k(n) - 3, Math.min(9 - k(n), 1)));
  const hex = (v) => Math.round(v * 255).toString(16).padStart(2, '0');
  return `#${hex(f(0))}${hex(f(8))}${hex(f(4))}`;
}

export function initials(name) {
  const cleaned = name.replace(/^(https?:\/\/)?(mint\.|www\.)?/, '');
  const first = cleaned.trim()[0] ?? '?';
  if (/\d/.test(first)) return cleaned.slice(0, 2);
  return first.toUpperCase();
}

export function truncateMiddle(value, head = 10, tail = 8) {
  if (value.length <= head + tail + 1) return value;
  return `${value.slice(0, head)}…${value.slice(-tail)}`;
}

/** 4–5 star share vs 1–2 star share, as the site's sentiment bar splits them. */
export function sentiment(dist) {
  const positive = (dist['5'] ?? 0) + (dist['4'] ?? 0);
  const negative = (dist['2'] ?? 0) + (dist['1'] ?? 0);
  const total = positive + negative + (dist['3'] ?? 0);
  if (total === 0) return null;
  return {
    pos: Math.round((positive / total) * 100),
    neg: Math.round((negative / total) * 100),
  };
}

/** "500k", "1M", "100" — sat amounts at stats-bar size. */
export function compactSats(n) {
  if (n >= 1_000_000) return trim(n / 1_000_000) + 'M';
  if (n >= 1_000) return trim(n / 1_000) + 'k';
  return String(n);
}

function trim(n) {
  const s = n.toFixed(1);
  return s.endsWith('.0') ? s.slice(0, -2) : s;
}

/** The warning cell's two lines, from the same warning object the page banner uses. */
function warningCell(warning, mint, now) {
  if (!warning) return null;

  const since = mint.last_online;
  const label = {
    'gone': 'Likely gone',
    'melt-disabled': 'No withdrawals',
    'frozen': 'Frozen',
    'melt-only': 'Melt only',
    'offline-long': 'Offline',
    'offline': 'Offline',
    'fedimint-offline': 'Reported offline',
  }[warning.kind];
  if (!label) return null;

  let sub;
  switch (warning.kind) {
    case 'gone':
    case 'offline-long':
    case 'offline':
    case 'fedimint-offline':
      sub = since !== null ? `Since ${shortDate(since)}` : 'Never reached';
      break;
    case 'melt-only':
      sub = 'Deposits disabled';
      break;
    case 'melt-disabled':
      sub = 'Deposits still open';
      break;
    case 'frozen':
      sub = 'Nothing moves in or out';
      break;
  }

  // The mint is also offline while a capability warning outranks that fact: the cell
  // still has to say so, the way the page banner folds it into its last sentence.
  if (['melt-only', 'melt-disabled', 'frozen'].includes(warning.kind) && mint.status === 'offline' && since !== null) {
    sub = `Offline since ${shortDate(since)}`;
  }

  return { kind: warning.kind, severity: warning.severity, label, sub };
}

/**
 * One Cashu mint's card model, from its detail payload.
 *
 * `iconHash` arrives from the caller (a digest of the cached icon bytes), so a mint
 * that changes its logo behind the same URL regenerates. `now` is passed in rather
 * than read here so fixtures render the same PNG forever.
 */
export function cashuModel(mint, { iconHash = null, now = Math.floor(Date.now() / 1000) } = {}) {
  const domain = displayDomain(mint.url);
  const name = (mint.name ?? '').trim() || domain.split('/')[0] || domain;
  const warning = getMintWarnings(mint, { now })[0] ?? null;
  const offline = mint.status === 'offline';
  const offlineDays =
    offline && mint.last_online !== null
      ? Math.max(0, Math.floor((now - mint.last_online) / DAY))
      : null;

  const limits = parseLimits(mint.info?.nuts, 4);
  const caps = readCapabilities(mint.info?.nuts);

  return {
    v: TEMPLATE_VERSION,
    type: 'cashu',
    slug: mint.host,
    name,
    domain,
    status: mint.status,
    offlineDays,
    rating: mint.rating_avg,
    reviewCount: mint.review_count,
    sentiment: sentiment(mint.rating_distribution ?? {}),
    lastReviewMonth: mint.last_review_at ? monthYear(mint.last_review_at) : null,
    limits:
      limits && (limits.min !== null || limits.max !== null) && !caps.mintDisabled
        ? { min: limits.min, max: limits.max, unit: limits.unit }
        : null,
    warning: warningCell(warning, mint, now),
    iconHash,
    gradient: iconHash ? null : iconGradient(domain),
    initials: iconHash ? null : initials(name),
  };
}

/** One federation's card model. Same skeleton, only honest fields. */
export function fedimintModel(fed, { iconHash = null, now = Math.floor(Date.now() / 1000) } = {}) {
  const federationId = fed.federation_id ?? '';
  const name = (fed.name ?? '').trim() || 'Unnamed federation';
  const warning = getMintWarnings(fed, { now })[0] ?? null;
  const announced = fed.status === 'announced';
  const offlineDays =
    fed.status === 'offline' && fed.last_online !== null
      ? Math.max(0, Math.floor((now - fed.last_online) / DAY))
      : null;

  return {
    v: TEMPLATE_VERSION,
    type: 'fedimint',
    slug: fed.host,
    name,
    /** `fed11…` prefix plus the id tail: what the identity row shows where a domain sits. */
    shortId: federationId ? `fed11…${federationId.slice(-6)}` : fed.host,
    status: fed.status,
    offlineDays,
    rating: fed.rating_avg,
    reviewCount: fed.review_count,
    sentiment: sentiment(fed.rating_distribution ?? {}),
    lastReviewMonth: fed.last_review_at ? monthYear(fed.last_review_at) : null,
    modules: fed.modules ?? [],
    network: fed.network,
    /** The soft warning: never a red cell, just this muted line under the identity row. */
    announcedNote:
      announced && warning?.kind === 'never-confirmed' && fed.announced_at
        ? `Announced ${shortDate(fed.announced_at)}, never confirmed`
        : null,
    warning: fed.status === 'offline' ? warningCell(warning, fed, now) : null,
    iconHash,
    gradient: iconHash ? null : iconGradient(federationId || fed.host),
    initials: iconHash ? null : initials(name),
  };
}

/** The default card: brand, tagline, and the network's own numbers. */
export function defaultModel(stats) {
  return {
    v: TEMPLATE_VERSION,
    type: 'default',
    slug: 'default',
    mints: stats.cashu_total,
    federations: stats.fedimint_total,
    reviews: stats.reviews_total,
  };
}