import { Badge } from '../ui/primitives'
import { STAGE_FROM_STATUS } from '../api/pipeline'
import { fmtDateTime, toDate, toInstant } from '../lib/format'
import { Link } from 'react-router-dom'

const SOURCE_LABEL = {
  inbox: 'Email',
  manual: 'Manual',
  form: 'Form',
  ats: 'ATS',
  filtered: 'Email',
}

const STAGE_BADGE = {
  Shortlist: 'b-indigo',
  Screening: 'b-teal',
  Assessment: 'b-purple',
  Interview: 'b-amber',
  Offer: 'b-green',
  Approved: 'b-green',
  Hired: 'b-green',
  'On Hold': 'b-amber',
  Rejected: 'b-gray',
  'Rejected — wrong format': 'b-red',
  'No job assigned': 'b-gray',
}

export function applicationStatusLabel(status, item) {
  if (item?.rejection_reason === 'wrong_format' || String(status || '').toUpperCase() === 'WRONG_FORMAT') {
    return 'Rejected — wrong format'
  }
  const assigned = Boolean(item?.job_post_id || item?.jobPostId || (item?.source === 'form' && (item.job_title || item.jobTitle)))
  if (!assigned && (status == null || status === '' || String(status).toUpperCase() === 'CLOSED')) {
    return 'No job assigned'
  }
  if (status == null || status === '') return 'Shortlist'
  const key = String(status).toUpperCase()
  if (STAGE_FROM_STATUS[key]) return STAGE_FROM_STATUS[key]
  const extras = {
    UNREAD: 'Unread',
    IMPORTED: 'Imported',
    PROCESSED: 'Processed',
    COMPLETED: 'ATS scored',
    FAILED: 'ATS failed',
    BANKED: 'CV bank',
  }
  if (extras[key]) return extras[key]
  return key.charAt(0) + key.slice(1).toLowerCase()
}

function historyItemsOf(row) {
  if (!row) return []
  if (Array.isArray(row.previousApplications)) return row.previousApplications
  if (Array.isArray(row.previous_applications)) return row.previous_applications
  return []
}

/** Every application for this candidate, including the one currently open. */
export function candidateApplicationsOf(row) {
  if (!row) return []
  const current = currentRowIds(row)
  const items = [...historyItemsOf(row)]
  if (current.size && !items.some((item) => isSameApplication(item, current))) {
    const self = syntheticCurrentApplication(row)
    if (self) items.push(self)
  }
  items.sort((a, b) => (appliedAtMs(b?.applied_at) ?? 0) - (appliedAtMs(a?.applied_at) ?? 0))
  return items
}

/** Applications other than the open row — used by the Reapplied chip. */
export function previousApplicationsOf(row) {
  if (!row) return []
  const current = currentRowIds(row)
  return candidateApplicationsOf(row).filter((item) => !isSameApplication(item, current))
}

function syntheticCurrentApplication(row) {
  const assigned = row.assignedPost || row.assigned_job_post
  const position = row.kind !== 'email' && row.position && row.position !== '—' ? row.position : null
  const jobTitle = assigned?.title || row.job_title || row.jobTitle || row.currentTitle || position || null
  const kind = row.kind
  let source = row.source
  if (kind === 'form') source = 'form'
  else if (kind === 'email') source = 'inbox'
  else if (row.manualUploadId || row.manual_upload_candidate_id) source = 'manual'
  if (source && String(source).includes('@')) source = 'inbox'
  const id = row.id != null && row.id !== '' ? String(row.id) : null
  return {
    source: source || 'inbox',
    inbox_id: row.inboxId || row.inbox_id || null,
    message_id: kind === 'email' ? id : (row.message_id || null),
    form_data_id: kind === 'form' ? id : (row.form_data_id || null),
    manual_upload_candidate_id: row.manualUploadId || row.manual_upload_candidate_id || null,
    candidate_id: row.candidate_id || (kind == null && row.jobId ? row.id : null) || null,
    user_id: row.userId || row.user_id || null,
    job_post_id: row.assignedId || row.jobId || row.job_post_id || null,
    job_title: jobTitle,
    status: row.applicationStatus || row.processingState || row.status || null,
    applied_at: row.received || row.applied || row.applied_at || row.entry_date || row.when || null,
  }
}

function appliedAtMs(value) {
  if (value == null || value === '') return null
  if (value instanceof Date) {
    return Number.isNaN(value.getTime()) ? null : value.getTime()
  }
  const instant = toInstant(value)
  if (instant) return instant.getTime()
  const wall = toDate(value)
  return wall ? wall.getTime() : null
}

function currentRowIds(row) {
  return new Set(
    [
      row.id,
      row.inboxId,
      row.inbox_id,
      row.message_id,
      row.messageId,
      row.form_data_id,
      row.manualUploadId,
      row.manual_upload_candidate_id,
      row.candidate_id,
      row.upstream_id,
    ]
      .filter((v) => v != null && v !== '')
      .map(String),
  )
}

function isSameApplication(item, currentIds) {
  if (!item) return false
  return [
    item.inbox_id,
    item.message_id,
    item.upstream_id,
    item.form_data_id,
    item.manual_upload_candidate_id,
    item.candidate_id,
  ].some((id) => id != null && id !== '' && currentIds.has(String(id)))
}

function hasAssignedJob(item) {
  if (!item) return false
  if (item.job_post_id || item.jobPostId) return true
  return item.source === 'form' && Boolean(item.job_title || item.jobTitle)
}

export function isReapplicant(row) {
  if (!row) return false
  return previousApplicationsOf(row).some(hasAssignedJob)
}

export function previousApplicationsTip(row) {
  const items = previousApplicationsOf(row)
  if (!items.length) return 'Applied before'
  return items.map((item) => {
    const job = item.job_title || item.jobTitle || 'No job assigned'
    return `${job} — ${applicationStatusLabel(item.status, item)}`
  }).join('\n')
}

/** Compact chip for tables, kanban cards, and inbox rows. */
export function ReappliedBadge({ row, className = '' }) {
  if (!isReapplicant(row)) return null
  const count = previousApplicationsOf(row).filter(hasAssignedJob).length
  return (
    <span
      className={`badge b-amber badge-plain ${className}`.trim()}
      style={{ marginLeft: 6, fontSize: 10, padding: '1px 6px' }}
      title={previousApplicationsTip(row)}
    >
      Reapplied{count > 1 ? ` · ${count}` : ''}
    </span>
  )
}

export function hrefForPreviousApplication(item) {
  if (!item) return null
  if (item.source === 'form' && item.form_data_id) {
    return `/inbox?open=${encodeURIComponent(item.form_data_id)}&kind=form`
  }
  if ((item.source === 'inbox' || item.source === 'filtered') && item.message_id) {
    return `/inbox?open=${encodeURIComponent(item.message_id)}&kind=email`
  }
  if (item.source === 'manual') {
    if (item.user_id) return `/candidate/${encodeURIComponent(item.user_id)}`
    if (item.manual_upload_candidate_id) {
      return `/matching?record=${encodeURIComponent(item.manual_upload_candidate_id)}`
    }
  }
  if (item.user_id) return `/candidate/${encodeURIComponent(item.user_id)}`
  if (item.form_data_id) {
    return `/inbox?open=${encodeURIComponent(item.form_data_id)}&kind=form`
  }
  if (item.message_id) {
    return `/inbox?open=${encodeURIComponent(item.message_id)}&kind=email`
  }
  return null
}

/** Full application list for profile / inbox / add-candidate. */
export function PreviousApplications({ row, title = 'Total applications' }) {
  const items = candidateApplicationsOf(row)
  // One row is the application already on screen — do not show a history card.
  if (items.length < 2) return null
  const current = currentRowIds(row)
  const heading = title === 'Total applications' ? `Total applications (${items.length})` : title
  return (
    <div
      className="card"
      style={{
        boxShadow: 'none',
        background: 'var(--warning-soft)',
        border: '1px solid var(--warning)',
        marginBottom: 18,
      }}
    >
      <div className="card-body">
        <div
          style={{
            fontSize: 12,
            color: 'var(--warning)',
            fontWeight: 700,
            textTransform: 'uppercase',
            marginBottom: 10,
          }}
        >
          {heading}
        </div>
        <div style={{ display: 'flex', flexDirection: 'column', gap: 8 }}>
          {items.map((item, idx) => {
            const stage = applicationStatusLabel(item.status, item)
            const job = item.job_title || item.jobTitle || 'No job assigned'
            const href = hrefForPreviousApplication(item)
            const isCurrent = current.size > 0 && isSameApplication(item, current)
            const key = [
              item.source,
              item.inbox_id,
              item.manual_upload_candidate_id,
              item.form_data_id,
              item.candidate_id,
              item.job_post_id,
              idx,
            ].filter(Boolean).join(':')
            const jobLabel = (
              <>
                {job}
                {isCurrent ? ' (Current)' : ''}
              </>
            )
            return (
              <div
                key={key}
                className={`reapplicant-history-row flex items-center gap-8${href ? ' is-link' : ''}`}
                style={{ justifyContent: 'space-between', flexWrap: 'wrap' }}
              >
                <div style={{ minWidth: 0 }}>
                  {href ? (
                    <Link
                      to={href}
                      className="reapplicant-job-link"
                      title={isCurrent ? 'This application' : 'Open this application'}
                      onClick={(e) => e.stopPropagation()}
                    >
                      {jobLabel}
                    </Link>
                  ) : (
                    <div className="fw-600" style={{ fontSize: 13 }}>{jobLabel}</div>
                  )}
                  <div className="cell-sub">
                    {SOURCE_LABEL[item.source] || item.source || 'Application'}
                    {item.applied_at ? ` · ${fmtDateTime(toInstant(item.applied_at) || item.applied_at)}` : ''}
                  </div>
                </div>
                <Badge className={STAGE_BADGE[stage] || 'b-gray'}>{stage}</Badge>
              </div>
            )
          })}
        </div>
      </div>
    </div>
  )
}