HR-ATS-Portal/frontend/src/lib/format.js

/** Display formatting for identifiers stored snake_case in the DB. */

/** 'system_administrator' → 'System Administrator', 'INTERVIEW' → 'Interview'. */
export function formatRole(name) {
  const s = String(name || '').trim()
  if (!s) return s
  return s
    .split(/[_\s]+/)
    .map((w) => (w ? w[0].toUpperCase() + w.slice(1).toLowerCase() : w))
    .join(' ')
}

/* Platform date/time display. One spelling everywhere:
   date  → 3rd Sept 2026
   time  → 7:30pm  (12-hour, lowercase, no space)
   both  → 3rd Sept 2026 - 7:30pm

   Painted in Pakistan Standard Time (Asia/Karachi, UTC+5, no DST).
   Naive stamps (no Z / offset) are already PKT digits.
   UTC instants (…Z or +00:00) convert +5 to PKT. */
const MONTHS = ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sept', 'Oct', 'Nov', 'Dec']
const WEEKDAYS = ['Sunday', 'Monday', 'Tuesday', 'Wednesday', 'Thursday', 'Friday', 'Saturday']
const WEEKDAYS_SHORT = ['Sun', 'Mon', 'Tue', 'Wed', 'Thu', 'Fri', 'Sat']

const API_TS = /^(\d{4})-(\d{2})-(\d{2})(?:[T\s](\d{1,2}):(\d{2})(?::(\d{2})(?:\.\d+)?)?)?/

/** Parse an API timestamp into a Date whose local fields match the payload. */
export function toDate(value) {
  if (value == null || value === '') return null
  if (value instanceof Date) {
    return Number.isNaN(value.getTime()) ? null : value
  }
  if (typeof value === 'number' && Number.isFinite(value)) {
    const d = new Date(value)
    return Number.isNaN(d.getTime()) ? null : d
  }
  const s = String(value).trim()
  const m = s.match(API_TS)
  if (!m) return null
  const year = Number(m[1])
  const month = Number(m[2])
  const day = Number(m[3])
  const hour = m[4] != null ? Number(m[4]) : 0
  const minute = m[5] != null ? Number(m[5]) : 0
  const second = m[6] != null ? Number(m[6]) : 0
  if (month < 1 || month > 12 || day < 1 || day > 31) return null
  const d = new Date(year, month - 1, day, hour, minute, second)
  if (d.getFullYear() !== year || d.getMonth() !== month - 1 || d.getDate() !== day) return null
  return d
}

const HAS_OFFSET = /[zZ]|[+-]\d{2}:?\d{2}$/
/** Recruiter clock. PKT has no DST — UTC+5 year-round. */
const DISPLAY_TZ = 'Asia/Karachi'

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

function pktParts(d) {
  const out = {}
  for (const p of new Intl.DateTimeFormat('en-GB', {
    timeZone: DISPLAY_TZ,
    year: 'numeric',
    month: 'numeric',
    day: 'numeric',
    hour: 'numeric',
    minute: 'numeric',
    hourCycle: 'h23',
  }).formatToParts(d)) {
    if (p.type !== 'literal') out[p.type] = Number(p.value)
  }
  return out
}

/**
 * Parse a UTC instant (Graph receivedDateTime, timestamptz) into a Date
 * Display uses Asia/Karachi (PKT, UTC+5), not the browser zone.
 */
export function toInstant(value) {
  if (value == null || value === '') return null
  if (value instanceof Date) {
    return Number.isNaN(value.getTime()) ? null : value
  }
  if (typeof value === 'number' && Number.isFinite(value)) {
    const d = new Date(value)
    return Number.isNaN(d.getTime()) ? null : d
  }
  let s = String(value).trim()
  if (!s) return null
  if (/^\d{4}-\d{2}-\d{2}[ T]\d/.test(s) && !HAS_OFFSET.test(s)) {
    s = `${s.replace(' ', 'T')}Z`
  } else {
    s = s.replace(' ', 'T')
  }
  const d = new Date(s)
  return Number.isNaN(d.getTime()) ? null : d
}

function ordinal(n) {
  const v = n % 100
  if (v >= 11 && v <= 13) return `${n}th`
  switch (n % 10) {
    case 1: return `${n}st`
    case 2: return `${n}nd`
    case 3: return `${n}rd`
    default: return `${n}th`
  }
}

/** Date to paint. Naive ISO digits are PKT; Z / +00:00 are UTC → PKT. */
export function toDisplayDate(value) {
  if (value instanceof Date) {
    return Number.isNaN(value.getTime()) ? null : value
  }
  if (value == null || value === '') return null
  const s = String(value).trim()
  if (!s) return null
  if (HAS_OFFSET.test(s)) return toInstant(s) || toDate(s)
  const m = s.match(API_TS)
  if (m) {
    const hour = m[4] != null ? Number(m[4]) : 0
    const minute = m[5] != null ? Number(m[5]) : 0
    const second = m[6] != null ? Number(m[6]) : 0
    const iso = `${m[1]}-${m[2]}-${m[3]}T${pad2(hour)}:${pad2(minute)}:${pad2(second)}+05:00`
    const d = new Date(iso)
    if (!Number.isNaN(d.getTime())) return d
  }
  return toDate(s) || toInstant(s)
}

/** 3rd Sept 2026 (PKT calendar) */
export function fmtDate(value) {
  const d = toDisplayDate(value)
  if (!d) return ''
  const p = pktParts(d)
  if (p.day == null) return ''
  return `${ordinal(p.day)} ${MONTHS[p.month - 1]} ${p.year}`
}

/** Same as fmtDate — the platform uses one date spelling. */
export function fmtShort(value) {
  return fmtDate(value)
}

/** 7:30pm */
export function fmtTime(value) {
  const d = toDisplayDate(value)
  if (!d) return ''
  const p = pktParts(d)
  if (p.hour == null) return ''
  let hours = p.hour
  const minutes = p.minute
  const suffix = hours >= 12 ? 'pm' : 'am'
  hours = hours % 12
  if (hours === 0) hours = 12
  return `${hours}:${pad2(minutes)}${suffix}`
}

/** 3rd Sept 2026 - 7:30pm */
export function fmtDateTime(value, sep = ' - ') {
  const d = toDisplayDate(value)
  if (!d) return ''
  return `${fmtDate(d)}${sep}${fmtTime(d)}`
}

/** Sept 2026 — calendar month headers, not a day. */
export function fmtMonthYear(value) {
  const d = toDate(value)
  if (!d) return ''
  return `${MONTHS[d.getMonth()]} ${d.getFullYear()}`
}

/** Thursday, 3rd Sept 2026 — dashboard "today" line. */
export function fmtWeekdayDate(value) {
  const d = toDate(value)
  if (!d) return ''
  return `${WEEKDAYS[d.getDay()]}, ${fmtDate(d)}`
}

export function fmtWeekdayShort(value) {
  const d = toDate(value)
  if (!d) return ''
  return WEEKDAYS_SHORT[d.getDay()]
}

/** yyyy-mm-dd for <input type="date">, from the payload's calendar day. */
export function toDateInput(value) {
  const d = toDate(value)
  if (!d) return ''
  const y = d.getFullYear()
  const m = String(d.getMonth() + 1).padStart(2, '0')
  const day = String(d.getDate()).padStart(2, '0')
  return `${y}-${m}-${day}`
}