import { useCallback, useState } from 'react'
import { Loading, ErrorState } from '../../../components/PageState.jsx'
import { useAsync } from '../../../lib/useAsync.js'
import { ago, dateTime } from '../../../lib/format.js'
import { api } from '../../../api/client.js'
import { useSite } from '../../../contexts/SiteContext.jsx'
import { useAuth } from '../../../contexts/AuthContext.jsx'

export default function Dashboard() {
  const { refresh: refreshSite } = useSite()
  const { user } = useAuth()
  // PUT /admin/site-mode is adminOnly. The dashboard itself is staff-wide, so the
  // toggle needs its own gate — same rule the sidebar follows (AdminLayout: never
  // show a non-admin a control that would 403).
  const isAdmin = user?.role === 'admin'
  const [tick, setTick] = useState(0)
  const reload = useCallback(() => setTick((t) => t + 1), [])

  const { loading, error, data } = useAsync(
    () => Promise.all([api.admin.dashboard(), api.admin.listPosts(), api.admin.listWiki()]),
    [tick],
  )
  const [busy, setBusy] = useState(false)
  const [modeError, setModeError] = useState('')

  if (loading) return <Loading />
  if (error) return <ErrorState message="Could not load the dashboard." />

  const [dash, posts, wiki] = data
  const mode = dash.site_mode || 'live'
  const isLive = mode === 'live'
  const modeDot = isLive ? 'var(--mode-live)' : 'var(--mode-maint)'
  const published = posts.filter((p) => p.published).length

  const stats = [
    { value: published, label: 'Published posts' },
    { value: posts.length - published, label: 'Drafts' },
    { value: wiki.length, label: 'Wiki pages' },
    { value: dash.counts?.users ?? 0, label: 'Users' },
  ]

  // The rejection was previously unhandled: a refused toggle surfaced only as an
  // unhandled promise rejection in the console while the button silently reverted.
  async function toggle() {
    setBusy(true)
    setModeError('')
    try {
      await api.admin.setSiteMode(isLive ? 'maintenance' : 'live')
      await refreshSite()
      reload()
    } catch (err) {
      setModeError(
        err.status === 403
          ? 'Only an administrator can change the site mode.'
          : 'Could not change the site mode. Try again.',
      )
    } finally {
      setBusy(false)
    }
  }

  const changed = dash.last_change || {}

  let modeLabel = isLive ? 'Switch to Maintenance' : 'Switch to Live'
  if (busy) modeLabel = 'Saving…'

  return (
    <section>
      {/* Operator warnings: things that are quietly not working and would
          otherwise be discovered by someone not receiving an email. The list is
          normally empty, which is why it sits above the fold rather than in a
          panel — see ENGAGEMENT.md §1.2a (G22). */}
      {(dash.warnings || []).map((w) => (
        <div
          key={w.code}
          className="sans"
          style={{
            fontSize: '0.86rem',
            lineHeight: 1.5,
            borderRadius: 10,
            padding: '12px 16px',
            marginBottom: 18,
            border: '1px solid #7a6440',
            background: 'rgba(224,176,112,0.08)',
            color: '#e0b070',
          }}
        >
          {w.message}
          {w.href && (
            <>
              {' '}
              <a href={w.href} style={{ color: '#e0b070', textDecoration: 'underline' }}>Open settings</a>
            </>
          )}
        </div>
      ))}
      <div
        style={{
          display: 'flex',
          flexWrap: 'wrap',
          alignItems: 'center',
          justifyContent: 'space-between',
          gap: 18,
          padding: 24,
          border: '1px solid var(--line)',
          borderRadius: 12,
          background: 'var(--panel-grad)',
          marginBottom: 24,
        }}
      >
        <div>
          <div className="card-kicker" style={{ marginBottom: 8 }}>
            Site mode
          </div>
          <div style={{ display: 'flex', alignItems: 'center', gap: 10 }}>
            <span style={{ width: 11, height: 11, borderRadius: '50%', background: modeDot, boxShadow: `0 0 10px ${modeDot}` }} />
            <span className="display" style={{ fontSize: '1.5rem', color: 'var(--head)', textTransform: 'capitalize' }}>
              {mode}
            </span>
          </div>
          <div className="sans dim" style={{ fontSize: '0.8rem', marginTop: 6 }}>
            {changed.by ? `Changed by ${changed.by}` : 'No changes recorded'}
            {changed.at ? ` · ${dateTime(changed.at)}` : ''}
          </div>
          {modeError && (
            <div className="sans" style={{ fontSize: '0.8rem', marginTop: 8, color: 'var(--danger, #d98b8b)' }}>
              {modeError}
            </div>
          )}
        </div>
        {isAdmin && (
          <button
            onClick={toggle}
            disabled={busy}
            className="sans"
            style={{ border: '1px solid var(--accent)', borderRadius: 999, padding: '11px 24px', background: 'rgba(127,153,189,0.14)', color: '#d8e2ef', fontWeight: 600, fontSize: '0.9rem', cursor: 'pointer' }}
          >
            {modeLabel}
          </button>
        )}
      </div>

      <div className="grid-4" style={{ gap: 14, marginBottom: 28 }}>
        {stats.map((s) => (
          <div key={s.label} style={{ padding: 20, border: '1px solid var(--line)', borderRadius: 12, background: 'var(--panel-grad)' }}>
            <div className="display" style={{ fontSize: '2rem', color: 'var(--head)', lineHeight: 1 }}>
              {s.value}
            </div>
            <div className="card-kicker" style={{ marginTop: 8, marginBottom: 0 }}>
              {s.label}
            </div>
          </div>
        ))}
      </div>

      <h2 className="display" style={{ margin: '0 0 12px', fontSize: '1.25rem', color: 'var(--head)' }}>
        Recent activity
      </h2>
      <div className="panel-flat">
        {(dash.recent_activity || []).length === 0 && (
          <div className="adm-td" style={{ borderBottom: 'none' }}>No activity yet.</div>
        )}
        {(dash.recent_activity || []).map((a) => (
          <div
            key={a.id}
            className="sans"
            style={{ display: 'flex', gap: 14, alignItems: 'center', padding: '13px 18px', borderBottom: '1px solid var(--line-soft)', fontSize: '0.86rem' }}
          >
            <span style={{ flex: 'none', color: 'var(--accent)', fontSize: '0.66rem', fontWeight: 700, letterSpacing: '0.08em', textTransform: 'uppercase', width: 110, fontFamily: 'ui-monospace,Menlo,monospace' }}>
              {a.action}
            </span>
            <span style={{ flex: 1, color: 'var(--text)' }}>{formatDetail(a)}</span>
            <span className="dim" style={{ flex: 'none' }}>{ago(a.created_at)}</span>
          </div>
        ))}
      </div>
    </section>
  )
}

// Render the JSON `detail` column in a human-ish way.
export function formatDetail(a) {
  if (!a.detail) return a.username ? `by ${a.username}` : '—'
  try {
    const obj = JSON.parse(a.detail)
    return Object.entries(obj)
      .map(([k, v]) => `${k}: ${v}`)
      .join(', ')
  } catch {
    return a.detail
  }
}