'use strict';

/**
 * Service Times — reading the church website.
 *
 * Pure functions, no I/O, so every shape below can be checked without the
 * network (parse.test.js). The server entry does the fetching.
 *
 * Every campus page is built from the same page-builder blocks: a "Times"
 * heading, the day in bold, then the service times under it, ending before
 * the "Get Involved" heading. Bounding the slice that way is what keeps the
 * footer's main-office hours out of the service list — and some campuses
 * (Apollo Beach) carry their own "Office Hours" block inside the Times
 * section, which is why STOP_HEADINGS ends the walk early as well.
 *
 * The four shapes seen in the wild, all handled by walkSection():
 *
 *   Woonsocket / Apollo Beach   Sunday          → 9:00a, 11:00a
 *                               9:00a & 11:00a
 *   North Attleboro             Sunday          → 7:30a, 9:30a, 11:30a
 *                               7:30a<br>9:30a<br>11:30a
 *   Orlando                     Sundays         → Welcome 10:00a,
 *                               Welcome 10:00am    Start 10:30a
 *                               Start 10:30am
 */

const WEEKDAYS = [
  'sunday', 'monday', 'tuesday', 'wednesday', 'thursday', 'friday', 'saturday',
];

/** Headings that end the service list wherever they turn up in the section. */
const STOP_HEADINGS = /^(office\s*hours?|get\s*involved|location\s*pastor|contact|address|events?)\b/i;

/** A time: "9:00a", "11:30am", "7a", "10:00 a.m." — never "1 person". */
const TIME_RE = /(\d{1,2})(?::(\d{2}))?\s*([ap])\.?\s*(?:m\.?)?(?![a-z])/gi;

/** "9:00a-4:30p" — an hours range, not two services. */
const RANGE_RE = /\d\s*(?::\d{2})?\s*[ap]\.?m?\.?\s*[-–—]\s*\d/i;

const NAMED_ENTITIES = {
  amp: '&', nbsp: ' ', quot: '"', apos: "'", lt: '<', gt: '>',
  ndash: '–', mdash: '—', hellip: '…', middot: '·', bull: '•',
  rsquo: '’', lsquo: '‘', ldquo: '“', rdquo: '”',
};

function fromCodePoint(n) {
  try {
    return Number.isFinite(n) && n > 0 && n <= 0x10ffff ? String.fromCodePoint(n) : '';
  } catch {
    return '';
  }
}

function decodeEntities(input) {
  return String(input == null ? '' : input)
    .replace(/&#x([0-9a-f]+);/gi, (_, hex) => fromCodePoint(parseInt(hex, 16)))
    .replace(/&#(\d+);/g, (_, dec) => fromCodePoint(parseInt(dec, 10)))
    .replace(/&([a-z]+);/gi, (whole, name) => {
      const value = NAMED_ENTITIES[name.toLowerCase()];
      return value === undefined ? whole : value;
    });
}

/**
 * HTML → the lines a reader would see. Block ends and <br> become line
 * breaks so "7:30a<br>9:30a" stays two services rather than one run-on.
 */
function htmlToLines(html) {
  return String(html == null ? '' : html)
    .replace(/<(script|style)\b[^>]*>[\s\S]*?<\/\1>/gi, ' ')
    .replace(/<!--[\s\S]*?-->/g, ' ')
    .replace(/<br\s*\/?>/gi, '\n')
    .replace(/<\/(p|div|li|ul|ol|h[1-6]|td|tr|span|strong|b|em|i|a)\s*>/gi, '\n')
    .replace(/<[^>]*>/g, ' ')
    .split('\n')
    .map((line) => decodeEntities(line).replace(/[   ]/g, ' ').replace(/\s+/g, ' ').trim())
    .filter(Boolean);
}

/** Title Case a slug: "north-attleboro" → "North Attleboro". */
function nameFromSlug(slug) {
  return String(slug || '')
    .split(/[-_/]+/)
    .filter(Boolean)
    .map((word) => word.charAt(0).toUpperCase() + word.slice(1))
    .join(' ');
}

function slugify(name) {
  return String(name == null ? '' : name)
    .toLowerCase()
    .normalize('NFKD')
    .replace(/[^a-z0-9]+/g, '-')
    .replace(/^-+|-+$/g, '');
}

/** A weekday heading — "Sunday", "Sundays", "SUNDAY" — and nothing else. */
function dayFromLine(line) {
  const cleaned = String(line || '').toLowerCase().replace(/[^a-z]+/g, '');
  if (!cleaned) return '';
  for (const day of WEEKDAYS) {
    if (cleaned === day || cleaned === `${day}s`) {
      return day.charAt(0).toUpperCase() + day.slice(1);
    }
  }
  return '';
}

function pad2(n) {
  return String(n).padStart(2, '0');
}

/** "9:00a" → { hour24: 9, minute: 0, text: "9:00a" }; 12a/12p handled. */
function toService(hourRaw, minuteRaw, meridiemRaw) {
  const hour12 = Number(hourRaw);
  const minute = Number(minuteRaw || 0);
  const pm = String(meridiemRaw || '').toLowerCase() === 'p';
  if (!Number.isFinite(hour12) || hour12 < 1 || hour12 > 12) return null;
  if (!Number.isFinite(minute) || minute > 59) return null;
  const hour24 = pm ? (hour12 === 12 ? 12 : hour12 + 12) : hour12 === 12 ? 0 : hour12;
  return {
    hour24,
    minute,
    minutes: hour24 * 60 + minute,
    text: `${hour12}:${pad2(minute)}${pm ? 'p' : 'a'}`,
  };
}

/**
 * Times on one line, with the words in front of the first one as a label
 * ("Welcome 10:00am" → label "Welcome"). A line holding an hours range
 * ("9:00a-4:30p") is office hours, not services, and yields nothing.
 */
function timesFromLine(line) {
  const text = String(line || '');
  if (RANGE_RE.test(text)) return [];
  TIME_RE.lastIndex = 0;
  const found = [];
  let first = -1;
  let match = TIME_RE.exec(text);
  while (match) {
    const service = toService(match[1], match[2], match[3]);
    if (service) {
      if (first < 0) first = match.index;
      found.push(service);
    }
    match = TIME_RE.exec(text);
  }
  if (!found.length) return [];
  const label = first > 0
    ? text.slice(0, first).replace(/[\s|,;:&/–—-]+$/, '').trim()
    : '';
  // A label belongs to a single time ("Start 10:30am"); a list of times on
  // one line ("9:00a & 11:00a") shares none.
  return found.map((service) => ({ ...service, label: found.length === 1 ? label : '' }));
}

/**
 * Walk the lines of a Times section into services, stopping at the first
 * stop-heading. Lines before any weekday heading still count — a campus
 * that lists bare times under "Times" is read as Sunday.
 */
function walkSection(lines, { defaultDay = 'Sunday' } = {}) {
  const services = [];
  let day = '';
  for (const line of lines) {
    if (STOP_HEADINGS.test(line)) break;
    const heading = dayFromLine(line);
    if (heading) {
      day = heading;
      continue;
    }
    for (const service of timesFromLine(line)) {
      services.push({ ...service, day: day || defaultDay });
    }
  }
  return services;
}

/** Give every service a stable id — marks are keyed on it, so it must not drift. */
function withIds(services) {
  const seen = new Map();
  return services.map((service) => {
    const base = [
      pad2(service.hour24) + pad2(service.minute),
      slugify(service.label),
    ].filter(Boolean).join('-');
    const count = (seen.get(base) || 0) + 1;
    seen.set(base, count);
    return { ...service, id: count === 1 ? base : `${base}-${count}` };
  });
}

/** Drop exact duplicates (same day + time + label) while keeping order. */
function dedupe(services) {
  const seen = new Set();
  return services.filter((service) => {
    const key = `${service.day}|${service.minutes}|${service.label.toLowerCase()}`;
    if (seen.has(key)) return false;
    seen.add(key);
    return true;
  });
}

/**
 * The slice of a campus page between the "Times" heading and whatever ends
 * it. Returns '' when the page has no Times heading, which the caller
 * reports rather than guessing at.
 */
function timesSection(html) {
  const text = String(html == null ? '' : html);
  const start = /<([a-z0-9]+)\b[^>]*>\s*times\s*<\/\1\s*>/i.exec(text)
    || />\s*times\s*</i.exec(text);
  if (!start) return '';
  const from = start.index + start[0].length;
  const rest = text.slice(from);
  const end = /<([a-z0-9]+)\b[^>]*>\s*get\s+involved\s*<\/\1\s*>/i.exec(rest)
    || />\s*get\s+involved\s*</i.exec(rest);
  return end ? rest.slice(0, end.index) : rest.slice(0, 20000);
}

/**
 * One campus page → { slug, name, day, services, error }. `error` is set
 * (and services empty) when the page no longer looks the way this parser
 * expects, so the admin health line can say the site changed rather than
 * quietly showing a campus with no services.
 */
function parseCampusPage(html, { slug = '', name = '' } = {}) {
  const campusSlug = slugify(slug);
  const campusName = name || nameFromSlug(campusSlug);
  const section = timesSection(html);
  if (!section) {
    return { slug: campusSlug, name: campusName, services: [], error: 'No "Times" section on the page' };
  }
  const services = withIds(dedupe(walkSection(htmlToLines(section))));
  if (!services.length) {
    return { slug: campusSlug, name: campusName, services: [], error: 'No service times under "Times"' };
  }
  return { slug: campusSlug, name: campusName, services, error: '' };
}

/**
 * Campus page slugs from a sitemap and/or any page's links. The sitemap is
 * the fuller list — it carries campuses the navigation does not link yet.
 */
function discoverCampusSlugs(...sources) {
  const slugs = new Set();
  for (const source of sources) {
    const text = String(source == null ? '' : source);
    const re = /\/locations\/([a-z0-9][a-z0-9-]*)\/?/gi;
    let match = re.exec(text);
    while (match) {
      const slug = slugify(match[1]);
      if (slug && slug !== 'locations') slugs.add(slug);
      match = re.exec(text);
    }
  }
  return [...slugs].sort();
}

/**
 * The admin "Manual campuses" text: one campus per line,
 *
 *   Name | Day | 9:00a, 11:00a
 *
 * Day is optional and defaults to Sunday: "Plymouth | 9:00a & 11:00a".
 * A line the parser cannot read is returned in `errors` so the admin page
 * can say which line, rather than the campus silently not appearing.
 */
function parseManualCampuses(text) {
  const campuses = [];
  const errors = [];
  const lines = String(text == null ? '' : text).split(/\r?\n/);
  lines.forEach((raw, index) => {
    const line = raw.trim();
    if (!line || line.startsWith('#')) return;
    const parts = line.split('|').map((part) => part.trim());
    const name = parts.shift() || '';
    if (!name) return;
    if (!parts.length) {
      errors.push(`Line ${index + 1}: "${line}" has no times`);
      return;
    }
    let day = '';
    if (parts.length > 1) {
      day = dayFromLine(parts[0]) || '';
      if (day) parts.shift();
    }
    const services = withIds(dedupe(
      walkSection(parts.join('\n').split('\n'), { defaultDay: day || 'Sunday' })
    ));
    if (!services.length) {
      errors.push(`Line ${index + 1}: no times found in "${line}"`);
      return;
    }
    campuses.push({ slug: slugify(name), name, services, manual: true, error: '' });
  });
  return { campuses, errors };
}

/**
 * Website campuses and manual ones into the one list the tiles draw.
 *
 * The website wins: a manual campus is a stopgap for a site that has not
 * caught up, so as soon as the site publishes that campus (same slug) its
 * times take over and the manual entry is marked `supersededBy` — the admin
 * page says so, and the operator can delete the line.
 */
function mergeCampuses(siteCampuses, manualCampuses) {
  const merged = [];
  const bySlug = new Map();
  for (const campus of siteCampuses || []) {
    if (!campus || !campus.slug) continue;
    const entry = { ...campus, manual: false, superseded: false };
    bySlug.set(campus.slug, entry);
    merged.push(entry);
  }
  for (const campus of manualCampuses || []) {
    if (!campus || !campus.slug) continue;
    const fromSite = bySlug.get(campus.slug);
    if (fromSite) {
      // The site has it now — its times are the ones that matter.
      if (fromSite.services.length) {
        fromSite.supersededManual = true;
        continue;
      }
      // The page exists but gave us nothing usable; the manual line still helps.
      fromSite.services = campus.services;
      fromSite.manual = true;
      fromSite.error = '';
      continue;
    }
    const entry = { ...campus, superseded: false };
    bySlug.set(campus.slug, entry);
    merged.push(entry);
  }
  return merged;
}

/**
 * The admin "Resi sources" text: one campus per line,
 *
 *   woonsocket = north-attleboro
 *
 * Names work as well as slugs — both sides are slugified, so an operator can
 * write what they say out loud. "->", ":" and "→" read as "=".
 */
function parseFeeds(text) {
  const feeds = new Map();
  const errors = [];
  String(text == null ? '' : text).split(/\r?\n/).forEach((raw, index) => {
    const line = raw.trim();
    if (!line || line.startsWith('#')) return;
    const match = /^(.+?)\s*(?:=|->|:|→)\s*(.+)$/.exec(line);
    if (!match) {
      errors.push(`Line ${index + 1}: "${line}" is not "campus = broadcast campus"`);
      return;
    }
    const from = slugify(match[1]);
    const to = slugify(match[2]);
    if (!from || !to) {
      errors.push(`Line ${index + 1}: "${line}" is missing a campus`);
      return;
    }
    feeds.set(from, to);
  });
  return { feeds, errors };
}

/**
 * Give every campus its production role: which ones originate the broadcast,
 * which one each of the others takes its resi from, and — the question the
 * board exists to answer — who is riding on each origin.
 *
 * A resi campus pointed at a campus that is not on the board keeps the
 * pointer and is flagged (`sourceMissing`) rather than quietly reading as
 * unassigned: a typo in the admin text has to be visible, not invisible.
 */
function assignRoles(campuses, { broadcast = [], feeds = new Map() } = {}) {
  const origins = new Set([...broadcast].map((slug) => slugify(slug)).filter(Boolean));
  const shaped = (campuses || []).map((campus) => {
    const role = origins.has(campus.slug) ? 'broadcast' : 'resi';
    const source = role === 'broadcast' ? '' : feeds.get(campus.slug) || '';
    return { ...campus, role, source, sourceName: '', sourceMissing: false, dependents: [] };
  });
  const bySlug = new Map(shaped.map((campus) => [campus.slug, campus]));
  for (const campus of shaped) {
    if (!campus.source) continue;
    const origin = bySlug.get(campus.source);
    campus.sourceName = origin ? origin.name : campus.source;
    campus.sourceMissing = !origin;
    if (origin) origin.dependents.push({ slug: campus.slug, name: campus.name });
  }
  return shaped;
}

module.exports = {
  WEEKDAYS,
  decodeEntities,
  htmlToLines,
  nameFromSlug,
  slugify,
  dayFromLine,
  timesFromLine,
  walkSection,
  timesSection,
  parseCampusPage,
  discoverCampusSlugs,
  parseManualCampuses,
  mergeCampuses,
  parseFeeds,
  assignRoles,
};