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

// Admin config for authentication providers. Local password + TOTP is always on
// (informational tab). Google/Discord are built-ins with a fixed config surface
// (Enabled + Client ID + Client Secret). Custom providers use the full OIDC editor.

const TABS = [
  { id: 'local', label: 'Local Accounts' },
  { id: 'google', label: 'Google' },
  { id: 'discord', label: 'Discord' },
  { id: 'custom', label: 'Custom Providers' },
]

// The redirect/callback URL to register with the provider. Mirrors the server's
// redirect_uri (APP_BASE_URL + this path); shown so admins can copy it exactly.
function callbackUrl(id) {
  return `${window.location.origin}/api/v1/auth/sso/${id}/callback`
}

function HealthWarning({ provider }) {
  if (!provider || !provider.enabled || provider.health.valid) return null
  return (
    <p className="sans" style={{ margin: '4px 0 0', color: '#e0b070', fontSize: '0.82rem', lineHeight: 1.5 }}>
      Enabled but incomplete (missing: {provider.health.missing.join(', ')}). Hidden from the login
      page until fully configured.
    </p>
  )
}

function CallbackHint({ id }) {
  return (
    <div style={{ marginTop: 4 }}>
      <span className="field-label">Redirect / callback URL (register this with the provider)</span>
      <code
        className="sans"
        style={{ display: 'block', padding: '9px 12px', borderRadius: 8, border: '1px solid var(--line)', background: 'var(--bg-deep)', color: 'var(--muted)', fontSize: '0.82rem', wordBreak: 'break-all' }}
      >
        {callbackUrl(id)}
      </code>
    </div>
  )
}

// Live = enabled and healthy; Incomplete = enabled but missing/invalid config;
// Disabled otherwise.
function ProviderStatus({ provider: p }) {
  if (p.enabled && p.health.valid) return <span className="sans" style={{ color: '#7fd0a4' }}>Live</span>
  if (p.enabled) return <span className="sans" style={{ color: '#e0b070' }}>Incomplete</span>
  return <span className="sans dim">Disabled</span>
}

function Toggle({ checked, onChange, label }) {
  return (
    <label className="sans" style={{ display: 'inline-flex', alignItems: 'center', gap: 10, cursor: 'pointer', fontSize: '0.9rem', color: 'var(--ink)' }}>
      <input type="checkbox" checked={checked} onChange={(e) => onChange(e.target.checked)} />
      {label}
    </label>
  )
}

// ── Built-in (Google / Discord) config form ────────────────────────────────
function BuiltinForm({ provider, onSaved }) {
  const [enabled, setEnabled] = useState(provider.enabled)
  const [clientId, setClientId] = useState(provider.clientId || '')
  const [secret, setSecret] = useState('')
  const [busy, setBusy] = useState(false)
  const [msg, setMsg] = useState('')
  const [error, setError] = useState('')

  // Re-sync when switching between provider tabs.
  useEffect(() => {
    setEnabled(provider.enabled)
    setClientId(provider.clientId || '')
    setSecret('')
    setMsg('')
    setError('')
  }, [provider.id]) // eslint-disable-line react-hooks/exhaustive-deps

  async function save() {
    setBusy(true)
    setMsg('')
    setError('')
    try {
      const body = { enabled, clientId }
      if (secret) body.secret = secret // only send a new secret when entered
      await api.admin.updateAuthProvider(provider.id, body)
      setSecret('')
      setMsg('Saved.')
      await onSaved()
    } catch (err) {
      setError(err.message || 'Could not save.')
    } finally {
      setBusy(false)
    }
  }

  return (
    <div style={{ maxWidth: 560, display: 'flex', flexDirection: 'column', gap: 16 }}>
      <div style={{ display: 'flex', alignItems: 'center', gap: 12 }}>
        <span style={{ display: 'inline-flex', width: 26, height: 26 }}>
          <ProviderIcon icon={provider.kind} size={26} />
        </span>
        <h2 className="display" style={{ margin: 0, fontSize: '1.2rem', color: 'var(--head)' }}>
          {provider.name}
        </h2>
      </div>

      <Toggle checked={enabled} onChange={setEnabled} label="Enable this sign-in method" />
      <HealthWarning provider={provider} />

      <label style={{ display: 'block' }}>
        <span className="field-label">Client ID</span>
        <input type="text" value={clientId} onChange={(e) => setClientId(e.target.value)} className="input" autoComplete="off" />
      </label>

      <label style={{ display: 'block' }}>
        <span className="field-label">Client Secret</span>
        <input
          type="password"
          value={secret}
          onChange={(e) => setSecret(e.target.value)}
          className="input"
          autoComplete="new-password"
          placeholder={provider.hasSecret ? '•••••••• configured — leave blank to keep' : 'Client secret'}
        />
      </label>

      <CallbackHint id={provider.id} />

      <div style={{ display: 'flex', gap: 10, alignItems: 'center', marginTop: 4 }}>
        <button onClick={save} disabled={busy} className="btn btn-primary btn-sq">
          {busy ? 'Saving…' : 'Save changes'}
        </button>
        {msg && <span className="sans" style={{ color: '#7fd0a4', fontSize: '0.85rem' }}>{msg}</span>}
        {error && <span className="sans" style={{ color: '#d98b84', fontSize: '0.85rem' }}>{error}</span>}
      </div>
    </div>
  )
}

// ── Local accounts (informational) ─────────────────────────────────────────
function LocalInfo() {
  return (
    <div style={{ maxWidth: 560 }}>
      <h2 className="display" style={{ marginTop: 0, fontSize: '1.2rem', color: 'var(--head)' }}>
        Local accounts
      </h2>
      <p className="sans" style={{ color: 'var(--muted)', fontSize: '0.9rem', lineHeight: 1.6 }}>
        Username &amp; password sign-in (with optional TOTP two-factor) is always enabled and cannot
        be turned off — it is how you manage accounts and link SSO identities. Manage users under
        <strong> Users</strong>, and your own two-factor under <strong>Account</strong>.
      </p>
    </div>
  )
}

// ── Custom OIDC/OAuth2 providers ────────────────────────────────────────────
const EMPTY_CUSTOM = {
  id: '', name: '', kind: 'oidc', enabled: false, clientId: '', secret: '',
  authorizeUrl: '', tokenUrl: '', userinfoUrl: '', scopes: 'openid email profile', priority: 100,
}

function CustomEditor({ initial, onDone, onCancel }) {
  const isNew = !initial.id
  const [f, setF] = useState(isNew ? EMPTY_CUSTOM : { ...initial, secret: '' })
  const [busy, setBusy] = useState(false)
  const [error, setError] = useState('')
  const set = (k) => (e) => setF((prev) => ({ ...prev, [k]: e.target.value }))

  async function save() {
    setBusy(true)
    setError('')
    try {
      const body = {
        name: f.name, kind: f.kind, enabled: f.enabled, clientId: f.clientId,
        authorizeUrl: f.authorizeUrl, tokenUrl: f.tokenUrl, userinfoUrl: f.userinfoUrl,
        scopes: f.scopes, priority: Number(f.priority) || 100,
      }
      if (f.secret) body.secret = f.secret
      if (isNew) await api.admin.createAuthProvider({ id: f.id, ...body })
      else await api.admin.updateAuthProvider(initial.id, body)
      await onDone()
    } catch (err) {
      setError(err.message || 'Could not save provider.')
    } finally {
      setBusy(false)
    }
  }

  return (
    <div style={{ border: '1px solid var(--line)', borderRadius: 10, padding: 20, marginTop: 16, display: 'flex', flexDirection: 'column', gap: 14, maxWidth: 640 }}>
      <h3 className="display" style={{ margin: 0, fontSize: '1.05rem', color: 'var(--head)' }}>
        {isNew ? 'Add custom provider' : `Edit ${initial.name}`}
      </h3>
      {isNew && (
        <div style={{ display: 'grid', gridTemplateColumns: '1fr 1fr', gap: 12 }}>
          <label>
            <span className="field-label">ID (slug)</span>
            <input className="input" value={f.id} onChange={set('id')} placeholder="authentik" />
          </label>
          <label>
            <span className="field-label">Type</span>
            <select className="input" value={f.kind} onChange={set('kind')}>
              <option value="oidc">OIDC</option>
              <option value="oauth2">OAuth2</option>
            </select>
          </label>
        </div>
      )}
      <label>
        <span className="field-label">Display name</span>
        <input className="input" value={f.name} onChange={set('name')} placeholder="Authentik" />
      </label>
      <div style={{ display: 'grid', gridTemplateColumns: '1fr 1fr', gap: 12 }}>
        <label>
          <span className="field-label">Client ID</span>
          <input className="input" value={f.clientId} onChange={set('clientId')} autoComplete="off" />
        </label>
        <label>
          <span className="field-label">Client Secret</span>
          <input className="input" type="password" value={f.secret} onChange={set('secret')} autoComplete="new-password" placeholder={!isNew && initial.hasSecret ? '•••• leave blank to keep' : ''} />
        </label>
      </div>
      <label>
        <span className="field-label">Authorization URL</span>
        <input className="input" value={f.authorizeUrl} onChange={set('authorizeUrl')} placeholder="https://idp.example/application/o/authorize/" />
      </label>
      <label>
        <span className="field-label">Token URL</span>
        <input className="input" value={f.tokenUrl} onChange={set('tokenUrl')} placeholder="https://idp.example/application/o/token/" />
      </label>
      <label>
        <span className="field-label">UserInfo URL</span>
        <input className="input" value={f.userinfoUrl} onChange={set('userinfoUrl')} placeholder="https://idp.example/application/o/userinfo/" />
      </label>
      <div style={{ display: 'grid', gridTemplateColumns: '2fr 1fr', gap: 12 }}>
        <label>
          <span className="field-label">Scopes</span>
          <input className="input" value={f.scopes} onChange={set('scopes')} />
        </label>
        <label>
          <span className="field-label">Priority</span>
          <input className="input" type="number" value={f.priority} onChange={set('priority')} />
        </label>
      </div>
      <Toggle checked={f.enabled} onChange={(v) => setF((p) => ({ ...p, enabled: v }))} label="Enabled" />
      {!isNew && <CallbackHint id={initial.id} />}
      <div style={{ display: 'flex', gap: 10, alignItems: 'center' }}>
        <button onClick={save} disabled={busy} className="btn btn-primary btn-sq">
          {busy ? 'Saving…' : 'Save provider'}
        </button>
        <button onClick={onCancel} disabled={busy} className="pill">Cancel</button>
        {error && <span className="sans" style={{ color: '#d98b84', fontSize: '0.85rem' }}>{error}</span>}
      </div>
    </div>
  )
}

function CustomProviders({ items, onChanged }) {
  const [editing, setEditing] = useState(null) // null | 'new' | provider

  async function del(p) {
    if (!window.confirm(`Delete provider "${p.name}"? This cannot be undone.`)) return
    await api.admin.deleteAuthProvider(p.id)
    await onChanged()
  }

  return (
    <div>
      <div style={{ display: 'flex', alignItems: 'center', justifyContent: 'space-between', marginBottom: 14, gap: 12, flexWrap: 'wrap' }}>
        <p className="sans muted" style={{ margin: 0, fontSize: '0.9rem' }}>
          OAuth2 / OIDC providers (Authentik, Keycloak, Okta, Azure AD, Zitadel, …)
        </p>
        {!editing && (
          <button onClick={() => setEditing('new')} className="btn btn-primary btn-sq">+ Add provider</button>
        )}
      </div>

      {items.length === 0 && !editing && (
        <p className="sans dim" style={{ fontSize: '0.88rem' }}>No custom providers yet.</p>
      )}

      {items.length > 0 && (
        <div className="panel-flat">
          <table className="adm-table">
            <thead>
              <tr>
                <th className="adm-th">Name</th>
                <th className="adm-th">Type</th>
                <th className="adm-th">Status</th>
                <th className="adm-th" />
              </tr>
            </thead>
            <tbody>
              {items.map((p) => (
                <tr key={p.id}>
                  <td className="adm-td" style={{ color: 'var(--head)' }}>{p.name}</td>
                  <td className="adm-td dim">{p.kind}</td>
                  <td className="adm-td">
                    <ProviderStatus provider={p} />
                  </td>
                  <td className="adm-td" style={{ textAlign: 'right' }}>
                    <span className="link-accent" onClick={() => setEditing(p)}>Edit</span>
                    <span className="link-accent" onClick={() => del(p)} style={{ marginLeft: 14, color: '#d98b84' }}>Delete</span>
                  </td>
                </tr>
              ))}
            </tbody>
          </table>
        </div>
      )}

      {editing && (
        <CustomEditor
          initial={editing === 'new' ? {} : editing}
          onCancel={() => setEditing(null)}
          onDone={async () => {
            setEditing(null)
            await onChanged()
          }}
        />
      )}
    </div>
  )
}

export default function AuthProvidersAdmin() {
  const [providers, setProviders] = useState(null)
  const [error, setError] = useState('')
  const [tab, setTab] = useState('local')

  const load = useCallback(async () => {
    try {
      setProviders(await api.admin.listAuthProviders())
    } catch {
      setError('Could not load authentication providers.')
    }
  }, [])
  useEffect(() => {
    load()
  }, [load])

  if (error) return <ErrorState message={error} />
  if (!providers) return <Loading />

  const byId = (id) => providers.find((p) => p.id === id)
  const customs = providers.filter((p) => !p.builtin)

  return (
    <section>
      <div style={{ display: 'flex', gap: 6, borderBottom: '1px solid var(--line-soft)', marginBottom: 24, flexWrap: 'wrap' }}>
        {TABS.map((t) => (
          <button
            key={t.id}
            onClick={() => setTab(t.id)}
            className="sans"
            style={{
              padding: '9px 16px',
              border: 'none',
              background: 'transparent',
              cursor: 'pointer',
              fontSize: '0.9rem',
              color: tab === t.id ? 'var(--head)' : 'var(--muted)',
              borderBottom: `2px solid ${tab === t.id ? 'var(--accent)' : 'transparent'}`,
              marginBottom: -1,
            }}
          >
            {t.label}
          </button>
        ))}
      </div>

      {tab === 'local' && <LocalInfo />}
      {tab === 'google' && <BuiltinForm provider={byId('google')} onSaved={load} />}
      {tab === 'discord' && <BuiltinForm provider={byId('discord')} onSaved={load} />}
      {tab === 'custom' && <CustomProviders items={customs} onChanged={load} />}
    </section>
  )
}