// Shared formatting helpers and the canonical entry-type palette.
// The type config here is the single source of truth for icon + color,
// reused by the calendar chips, map markers/popups, and the day editor.

// Order here drives the day-editor type picker and the calendar legend, so it
// is roughly most-common-first with Activity as the default for new entries.
export const ENTRY_TYPES = {
  activity: { label: 'Activity', icon: '📍', color: '#059669' },
  stay: { label: 'Stay', icon: '🏙️', color: '#f59e0b' },
  transport: { label: 'Transport', icon: '🚆', color: '#d97706' },
  flight: { label: 'Flight', icon: '✈️', color: '#2563eb' },
  rental: { label: 'Rental car', icon: '🚙', color: '#0891b2' },
  note: { label: 'Note', icon: '📝', color: '#64748b' },
};

export const ENTRY_TYPE_LIST = Object.entries(ENTRY_TYPES).map(([value, meta]) => ({
  value,
  ...meta,
}));

// Transport entries may carry an optional transport_mode; this is its own
// select (shown only for type === 'transport'), separate from ENTRY_TYPES.
export const TRANSPORT_MODES = [
  { value: 'train', label: 'Train', icon: '🚆' },
  { value: 'bus', label: 'Bus', icon: '🚌' },
  { value: 'ferry', label: 'Ferry', icon: '⛴️' },
  { value: 'taxi', label: 'Taxi', icon: '🚕' },
  { value: 'drive', label: 'Drive', icon: '🚗' },
  { value: 'other', label: 'Other', icon: '➡️' },
];

export function typeInfo(type) {
  return ENTRY_TYPES[type] || { label: type || 'Entry', icon: '•', color: '#64748b' };
}

// Icon for an entry: a transport entry with a mode shows the mode's icon,
// otherwise falls back to the type's icon.
export function entryIcon(entry) {
  if (entry && entry.type === 'transport' && entry.transport_mode) {
    const mode = TRANSPORT_MODES.find((m) => m.value === entry.transport_mode);
    if (mode) return mode.icon;
  }
  return typeInfo(entry && entry.type).icon;
}

// Expense categories (daily spending log) — fixed enum, see docs/API.md.
// Display metadata lives here per the API contract ("Display metadata (icon +
// label + colour) lives in the frontend ... not the API").
export const EXPENSE_CATEGORIES = {
  food: { label: 'Food', icon: '🍽️', color: '#059669' },
  drinks: { label: 'Drinks', icon: '🍹', color: '#0891b2' },
  transport: { label: 'Transport', icon: '🚕', color: '#d97706' },
  activities: { label: 'Activities', icon: '🎟️', color: '#2563eb' },
  shopping: { label: 'Shopping', icon: '🛍️', color: '#db2777' },
  accommodation: { label: 'Accommodation', icon: '🏨', color: '#f59e0b' },
  other: { label: 'Other', icon: '💸', color: '#64748b' },
};

export const EXPENSE_CATEGORY_LIST = Object.entries(EXPENSE_CATEGORIES).map(([value, meta]) => ({
  value,
  ...meta,
}));

export function expenseCategoryInfo(category) {
  return EXPENSE_CATEGORIES[category] || EXPENSE_CATEGORIES.other;
}

// Split modes with the human labels the day-editor select shows.
export const SPLIT_MODES = [
  { value: 'equal', label: 'Split equally' },
  { value: 'own', label: 'Everyone pays their own (price per person)' },
  { value: 'payer', label: "Payer's own expense" },
];

export function splitModeLabel(mode) {
  const found = SPLIT_MODES.find((m) => m.value === mode);
  return found ? found.label : mode;
}

// Account tokens / join codes: strip separators + uppercase, or regroup for
// display. Works whether the server sends the value raw or already grouped.
export function normalizeCode(str) {
  return String(str || '').replace(/[^A-Za-z0-9]/g, '').toUpperCase();
}

export function groupCode(str, size = 4) {
  const raw = normalizeCode(str);
  const groups = raw.match(new RegExp(`.{1,${size}}`, 'g'));
  return groups ? groups.join('-') : raw;
}

// Money as "1,234.56 USD". `compact` drops trailing zeros ("1,200 THB").
export function formatMoney(amount, currency = 'USD', { compact = false } = {}) {
  const n = Number(amount) || 0;
  const s = n.toLocaleString(undefined, compact
    ? { maximumFractionDigits: 2 }
    : { minimumFractionDigits: 2, maximumFractionDigits: 2 });
  return `${s} ${currency}`;
}

// Parse a YYYY-MM-DD string as a *local* date (avoid UTC off-by-one).
export function parseYMD(str) {
  const [y, m, d] = String(str).split('-').map(Number);
  return new Date(y, (m || 1) - 1, d || 1);
}

export function ymd(date) {
  const y = date.getFullYear();
  const m = String(date.getMonth() + 1).padStart(2, '0');
  const d = String(date.getDate()).padStart(2, '0');
  return `${y}-${m}-${d}`;
}

export function addDays(date, n) {
  const d = new Date(date);
  d.setDate(d.getDate() + n);
  return d;
}

export function daysBetweenInclusive(startStr, endStr) {
  const a = parseYMD(startStr);
  const b = parseYMD(endStr);
  return Math.round((b - a) / 86400000) + 1;
}

export function eachDay(startStr, endStr) {
  const out = [];
  let d = parseYMD(startStr);
  const end = parseYMD(endStr);
  while (d <= end) {
    out.push(ymd(d));
    d = addDays(d, 1);
  }
  return out;
}

// Monday-based start of the week containing `date`.
export function startOfWeekMon(date) {
  const d = new Date(date);
  const offset = (d.getDay() + 6) % 7; // 0 = Monday
  return addDays(d, -offset);
}

export function formatDate(str, opts = { month: 'short', day: 'numeric' }) {
  return parseYMD(str).toLocaleDateString(undefined, opts);
}

export function formatFullDate(str) {
  return parseYMD(str).toLocaleDateString(undefined, {
    weekday: 'long',
    month: 'long',
    day: 'numeric',
    year: 'numeric',
  });
}

export function formatRange(startStr, endStr) {
  const s = parseYMD(startStr);
  const e = parseYMD(endStr);
  const sameYear = s.getFullYear() === e.getFullYear();
  const sOpts = sameYear
    ? { month: 'short', day: 'numeric' }
    : { month: 'short', day: 'numeric', year: 'numeric' };
  const eOpts = { month: 'short', day: 'numeric', year: 'numeric' };
  return `${s.toLocaleDateString(undefined, sOpts)} – ${e.toLocaleDateString(undefined, eOpts)}`;
}

export function formatTimeRange(start, end) {
  if (start && end) return `${start}–${end}`;
  return start || end || '';
}

export function pluralize(n, one, many) {
  return `${n} ${n === 1 ? one : many || one + 's'}`;
}

// "CNX→BKK→DXB→FRA" from a flight entry's segments array.
export function flightChain(segments) {
  if (!Array.isArray(segments) || segments.length === 0) return '';
  const codes = [segments[0]?.from?.code, ...segments.map((s) => s?.to?.code)].filter(Boolean);
  return codes.join('→');
}

export function hasSegments(entry) {
  return entry && Array.isArray(entry.segments) && entry.segments.length > 0;
}

export function hasRental(entry) {
  return entry && entry.rental && typeof entry.rental === 'object';
}

// True when an entry spans more than its start day (valid end_date after date).
export function isMultiDay(entry) {
  return !!(entry && entry.end_date && entry.end_date > entry.date);
}

// Inclusive span in days (end_date null → 1).
export function entrySpanDays(entry) {
  const end = entry.end_date && entry.end_date >= entry.date ? entry.end_date : entry.date;
  return daysBetweenInclusive(entry.date, end);
}

// A stay's short label: first comma-segment of its location name (fallback title).
export function stayShortName(entry) {
  const base = entry.location_name || entry.title || 'Stay';
  return base.split(',')[0].trim();
}