import { useCallback, useEffect, useState } from 'react'
import { Loading, ErrorState } from '../../../components/PageState.jsx'
import { api } from '../../../api/client.js'

// Admin → Engagement → Send Log (ENGAGEMENT.md §4.5, gap G15, Phase 5b).
//
// G15 was stated as: "no per-message record — no send log, no delivery status, no
// audit". The table has been filling since Phase 4a; this is the screen that reads
// it, and the question it exists to answer is the operator's, not the engine's:
// **did that person get that mail, and if not, why not?**
//
// Two things it deliberately does not show.
//
//   • **The address.** The log stores a sha256 so a bounce can be correlated back
//     to a recipient (Phase 9) without becoming a second address book. The route
//     strips the column; this screen could not render it if it wanted to.
//   • **A name for the user.** The `user_id` is what the log holds, and joining
//     users in would make a delivery screen into a directory. The id is enough to
//     paste into Moderation, which is where a person's record belongs.
//
// `failed` rows are the point of the screen, so the reason is a column and not a
// tooltip: a delivery log whose failures need a hover is a log nobody reads.

const STATUS_LABEL = {
  sent: 'Sent',
  failed: 'Failed',
  suppressed: 'Not sent',
  bounced: 'Bounced',
  complained: 'Marked as spam',
}

const STATUS_COLOR = {
  failed: '#d98b84',
  bounced: '#d98b84',
  complained: '#d98b84',
}

const PAGE = 50

export default function EngagementSendLog() {
  const [rows, setRows] = useState([])
  const [total, setTotal] = useState(0)
  const [offset, setOffset] = useState(0)
  const [status, setStatus] = useState('')
  const [testTrigger, setTestTrigger] = useState('')
  // Phase 14. `total` is now a truncated number, and a screen that shows a total
  // without saying so is quietly wrong about the deployment's own history — this
  // is the fix for that, and the reason the horizon got an operator-facing
  // control rather than the invisible settings row the other two sweeps use.
  const [retainDays, setRetainDays] = useState(null)
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState(null)

  const load = useCallback(async (nextOffset, nextStatus) => {
    const result = await api.admin.listEngagementSends({
      limit: PAGE,
      offset: nextOffset,
      status: nextStatus || undefined,
    })
    setRows(result.sends || [])
    setTotal(result.total || 0)
    setTestTrigger(result.testSendTrigger || '')
    // Best-effort and non-blocking: the log is worth showing even if the policy
    // cannot be read, so a failure here leaves the note off rather than the
    // screen empty.
    try {
      const policy = await api.admin.getEngagementRetention()
      setRetainDays(policy?.retention?.sends ?? null)
    } catch {
      setRetainDays(null)
    }
  }, [])

  useEffect(() => {
    let alive = true
    ;(async () => {
      setLoading(true)
      try {
        await load(offset, status)
        if (alive) setError(null)
      } catch (err) {
        if (alive) setError(err.message)
      } finally {
        if (alive) setLoading(false)
      }
    })()
    return () => { alive = false }
  }, [load, offset, status])

  if (loading && rows.length === 0) return <Loading />
  if (error) return <ErrorState message={error} />

  const to = Math.min(offset + PAGE, total)

  return (
    <section>
      <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', gap: 16, marginBottom: 16, flexWrap: 'wrap' }}>
        <p className="sans" style={{ margin: 0, fontSize: '0.86rem', color: 'var(--muted)', maxWidth: 560 }}>
          Every message this deployment tried to deliver, successful or not. Addresses are not kept
          here — only a one-way hash, so a bounce can be matched back without the log becoming a
          second address book.
        </p>
        <label>
          <span className="field-label">Show</span>
          <select className="select" value={status} onChange={(e) => { setOffset(0); setStatus(e.target.value) }}>
            <option value="">Everything</option>
            <option value="sent">Sent</option>
            <option value="failed">Failed</option>
            <option value="suppressed">Not sent</option>
            <option value="bounced">Bounced</option>
            <option value="complained">Marked as spam</option>
          </select>
        </label>
      </div>

      {total === 0 ? (
        <p className="sans dim" style={{ fontSize: '0.85rem' }}>
          {status ? 'Nothing matches that filter.' : 'Nothing has been sent yet.'}
        </p>
      ) : (
        <>
          <div className="panel-flat">
            <table className="adm-table">
              <thead>
                <tr>
                  <th className="adm-th">When</th>
                  <th className="adm-th">What</th>
                  <th className="adm-th">To</th>
                  <th className="adm-th">Channel</th>
                  <th className="adm-th">Result</th>
                  <th className="adm-th">Detail</th>
                </tr>
              </thead>
              <tbody>
                {rows.map((r) => (
                  <tr key={r.id}>
                    <td className="adm-td" style={{ whiteSpace: 'nowrap', fontSize: '0.8rem' }}>
                      {new Date(r.created_at).toLocaleString()}
                    </td>
                    <td className="adm-td" style={{ fontSize: '0.82rem' }}>
                      {/* The synthetic test-send id is rendered by name: it is not a
                          registered trigger and will never appear in the catalog,
                          so showing the raw id would send someone looking for it. */}
                      {r.trigger_id === testTrigger
                        ? <span>Test send <span className="dim">from the template editor</span></span>
                        : <code style={{ fontSize: '0.8rem' }}>{r.trigger_id}</code>}
                    </td>
                    <td className="adm-td" style={{ fontSize: '0.82rem' }}>
                      {r.user_id ? <span className="dim">user #{r.user_id}</span> : <span className="dim">—</span>}
                    </td>
                    <td className="adm-td" style={{ fontSize: '0.82rem' }}>
                      {r.channel}
                      {r.transport && <span className="dim"> · {r.transport}</span>}
                    </td>
                    <td className="adm-td" style={{ fontSize: '0.82rem', color: STATUS_COLOR[r.status] || undefined }}>
                      {STATUS_LABEL[r.status] || r.status}
                    </td>
                    <td className="adm-td" style={{ fontSize: '0.8rem', maxWidth: 320, overflowWrap: 'anywhere' }}>
                      {r.detail || ''}
                    </td>
                  </tr>
                ))}
              </tbody>
            </table>
          </div>

          <div style={{ display: 'flex', justifyContent: 'space-between', alignItems: 'center', marginTop: 14 }}>
            <span className="sans dim" style={{ fontSize: '0.82rem' }}>
              {offset + 1}–{to} of {total}
              {retainDays ? ` · entries older than ${retainDays} days are removed automatically` : ''}
            </span>
            <div style={{ display: 'flex', gap: 8 }}>
              <button type="button" className="pill" style={{ fontSize: '0.74rem' }}
                disabled={offset === 0} onClick={() => setOffset(Math.max(0, offset - PAGE))}>
                Newer
              </button>
              <button type="button" className="pill" style={{ fontSize: '0.74rem' }}
                disabled={to >= total} onClick={() => setOffset(offset + PAGE)}>
                Older
              </button>
            </div>
          </div>
        </>
      )}
    </section>
  )
}