import { useEffect, useState } from 'react'
import { useNavigate, useParams } from 'react-router-dom'
import { useZino } from '../api/provider.jsx'
import { CHANNELS, RV_LEADS, STAGES, phaseOf } from '../api/config.js'
import { describeError } from '../api/errors.js'

/** Short absolute date plus how long ago — a queue needs both: the absolute
 *  for "when exactly", the relative for "is this going stale". */
function added(ts) {
  if (!ts) return { abs: '—', rel: '' }
  const d = new Date(ts)
  if (isNaN(d)) return { abs: String(ts), rel: '' }
  const mins = Math.round((Date.now() - d.getTime()) / 60000)
  const rel = mins < 1 ? 'just now'
    : mins < 60 ? mins + 'm ago'
    : mins < 1440 ? Math.round(mins / 60) + 'h ago'
    : Math.round(mins / 1440) + 'd ago'
  return {
    abs: d.toLocaleString('en-IN', { day: 'numeric', month: 'short', hour: '2-digit', minute: '2-digit' }),
    rel,
  }
}

/**
 * Is an automated stage actually moving?
 *
 * The agents carry six of the nine stages, and a lead sitting in one is in
 * exactly one of two states: being worked right now, or stuck. The row showed
 * neither, so a lead three hours into "Calling the customer" looked identical
 * to one thirty seconds in — which is the failure this console exists to catch.
 *
 * The threshold is generous on purpose. An employee wake takes a minute or two
 * and a scheduled retry can be hours out, so `stalled` means "longer than any
 * normal step", not "longer than average".
 */
function progress(row, stage) {
  if (!stage || stage.kind !== 'auto') return null
  // `updated_at` ONLY. Falling back to created_at dates the measure from when
  // the lead was filed rather than from its last step, so every lead older than
  // half an hour reports "stalled" — an alarm on every row is an alarm on none.
  // The view returns the column since 76; before that it was silently absent,
  // which is exactly how that fallback got there.
  const t = Date.parse(row.updated_at)
  if (isNaN(t)) return null
  const mins = (Date.now() - t) / 60000
  if (mins < 3) return { state: 'working', label: stage.doing }
  if (mins < 30) return { state: 'waiting', label: stage.doing }
  return { state: 'stalled', label: 'No movement for ' + (mins < 120 ? Math.round(mins) + ' minutes' : Math.round(mins / 60) + ' hours') }
}

/** Days to expiry, and how alarmed to be about it. This is a renewal book —
 *  the countdown is the most operationally useful number in the row. */
function expiry(dateStr) {
  if (!dateStr) return null
  const d = new Date(String(dateStr).substring(0, 10) + 'T00:00:00Z')
  if (isNaN(d)) return null
  const days = Math.round((d.getTime() - Date.parse(new Date().toISOString().substring(0, 10) + 'T00:00:00Z')) / 86400000)
  const tone = days < 0 ? 'lapsed' : days <= 7 ? 'urgent' : days <= 30 ? 'soon' : 'later'
  const label = days < 0 ? Math.abs(days) + 'd overdue' : days === 0 ? 'today' : 'in ' + days + 'd'
  return { days, tone, label, on: d.toLocaleDateString('en-IN', { day: 'numeric', month: 'short' }) }
}
import './screens.css'

/**
 * One record view drives every queue; the stage is a server-side filter on
 * current_state_name. Filtering server-side rather than fetching everything and
 * narrowing in the browser is what keeps a queue honest once there are more
 * leads than one page.
 */
export default function Pipeline() {
  const { stageUid } = useParams()
  const navigate = useNavigate()
  const { client } = useZino()
  // "all" is not a stage — it is every open lead in one list. An operator
  // wanting to find a lead should not have to guess which queue it is in.
  const isAll = stageUid === 'all'
  const stage = isAll
    ? { uid: 'all', name: 'All open leads', kind: 'all', by: 'everyone' }
    : STAGES.find((s) => s.uid === stageUid)

  const [state, setState] = useState({ status: 'loading', rows: [], total: 0, error: null })

  useEffect(() => {
    let cancelled = false

    // `quiet` is what makes polling bearable: the first load may show a skeleton,
    // a refresh may not — dropping back to the loading state every 30 seconds
    // would flash the whole queue away under whoever is reading it.
    function fetchRows(quiet) {
      if (!quiet) setState({ status: 'loading', rows: [], total: 0, error: null })
      return client
        .recordView(RV_LEADS, {
          limit: isAll ? 200 : 100,
          // No stage filter on the all view. Closed leads are dropped below
          // rather than in the query: one request beats three negations, and
          // 200 covers a demo book comfortably.
          ...(isAll ? {} : { filters: [{ field_key: 'current_state_name', value: stage?.name ?? '' }] }),
        })
        .then((res) => {
          if (cancelled) return
          let rows = res?.data ?? res?.rows ?? res?.records ?? []
          if (isAll) {
            const closed = new Set(STAGES.filter((x) => x.kind === 'end').map((x) => x.name))
            rows = rows.filter((r) => !closed.has(r.current_state_name))
          }
          // total_count is the size of the QUEUE; rows is one page of at most
          // 100 of it. Counting the page would quietly under-report a busy stage.
          const total = isAll ? rows.length : (res?.pagination?.total_count ?? rows.length)
          setState({ status: 'ready', rows, total, error: null })
        })
        .catch((err) => {
          if (cancelled) return
          // A failed refresh must not throw away a queue that is already on
          // screen; only a failed first load is an error state.
          setState((prev) => (quiet && prev.status === 'ready' ? prev : { status: 'error', rows: [], total: 0, error: err }))
        })
    }

    fetchRows(false)
    const id = setInterval(() => {
      if (document.visibilityState === 'visible') fetchRows(true)
    }, 30000)

    return () => { cancelled = true; clearInterval(id) }
  }, [client, stageUid, stage?.name, isAll])

  if (!stage) return <p className="empty">Unknown stage.</p>

  return (
    <section>
      <header className="page__head">
        <div>
          <h1 className="page__title">{stage.need ?? stage.name}</h1>
          <p className="page__sub">
            {isAll
              ? 'Every lead not yet closed, across all stages.'
              : stage.kind === 'auto'
              ? `Automated · ${stage.doing.toLowerCase()}`
              : stage.kind === 'end'
                ? 'Closed — retained for reporting.'
                : stage.kind === 'waiting'
                  ? 'Held until the renewal window opens. Re-enters outreach automatically.'
                  : `Pending action by ${stage.by}.`}
            {stage.need ? <span className="page__stage">Stage · {stage.name}</span> : null}
          </p>
        </div>
        {state.status === 'ready' ? (
          <div className="page__count">
            <strong>{state.total}</strong>
            <span>{state.total === 1 ? 'lead' : 'leads'}</span>
          </div>
        ) : null}
      </header>

      {state.status === 'loading' ? (
        <div className="skel" aria-busy="true" aria-label="Loading the queue">
          {Array.from({ length: 6 }, (_, i) => <div className="skel__row" key={i} />)}
        </div>
      ) : null}

      {state.status === 'error' ? (
        <div className="notice">
          <strong>Unable to load this stage.</strong>
          <p>The lead list did not return. Other functions are unaffected; retry before escalating.</p>
          <p className="notice__detail">{describeError(state.error).title} · {state.error?.status} {state.error?.message}</p>
        </div>
      ) : null}

      {state.status === 'ready' && state.rows.length === 0 ? (
        <p className="empty">No records in this stage.</p>
      ) : null}

      {state.status === 'ready' && state.rows.length > 0 ? (
        <div className="gridwrap">
          <table className="grid">
            <thead>
              <tr>
                <th>Customer</th>
                <th>{isAll ? 'Stage' : 'Status'}</th>
                <th>Renewal due</th>
                <th className="num">Premium</th>
                <th>Waiting</th>
              </tr>
            </thead>
            <tbody>
              {state.rows.map((r) => {
                const id = r.instance_id ?? r.id
                const ch = CHANNELS[r.source_channel] || { label: r.source_channel || '—' }
                const exp = expiry(r.renewal_due_date)
                const add = added(r.created_at)
                // What is really happening in the state, not just its name —
                // a lead whose documents are in is being worked by the AI, not
                // waiting on the agent whose queue it is sitting in.
                const rowStage = phaseOf(STAGES.find((x) => x.name === r.current_state_name), r)
                const prog = progress(r, rowStage)
                return (
                  <tr
                    key={id}
                    className={'grid__row' + (prog ? ' is-' + prog.state : '')}
                    onClick={() => navigate(`/lead/${id}`)}
                    onKeyDown={(e) => {
                      if (e.key === 'Enter' || e.key === ' ') { e.preventDefault(); navigate(`/lead/${id}`) }
                    }}
                    tabIndex={0}
                    role="link"
                    aria-label={`Open ${r.customer_name || r.lead_ref || id}`}
                  >
                    <td>
                      <span className="grid__name">{r.customer_name || '—'}</span>
                      <div className="grid__sub">
                        {r.lead_ref || `#${id}`}
                        {r.product_line ? ` · ${r.product_line === 'motor' ? 'Motor' : 'SME'}` : ''}
                        {ch.label ? ` · ${ch.label}` : ''}
                      </div>
                    </td>
                    {/* Who holds it, and — where an agent does — whether it is
                        moving. On the all-leads view the stage name is the
                        useful column; inside a queue every row shares it, so
                        the useful thing is progress. */}
                    <td>
                      {prog ? (
                        <span className={'run run--' + prog.state}>
                          <span className="run__dot" aria-hidden="true" />
                          {prog.label}
                        </span>
                      ) : isAll ? (
                        <span className="grid__sub">{r.current_state_name || '—'}</span>
                      ) : (
                        <span className="grid__sub">
                          {rowStage?.by ? `with ${rowStage.by}` : '—'}
                        </span>
                      )}
                    </td>
                    <td>
                      {exp
                        ? <><span className={'due due--' + exp.tone}>{exp.label}</span>
                            <div className="grid__sub">{exp.on}</div></>
                        : <span className="grid__sub">—</span>}
                    </td>
                    <td className="num">{r.quoted_premium ? '₹' + Number(r.quoted_premium).toLocaleString('en-IN') : '—'}</td>
                    <td><span className="grid__sub">{add.rel || add.abs}</span></td>
                  </tr>
                )
              })}
            </tbody>
          </table>
        </div>
      ) : null}
    </section>
  )
}