import { useState, useEffect, useCallback } from 'react'
import { useParams, Link, useNavigate, useSearchParams } from 'react-router-dom'
import { databases, DATABASE_ID, COLLECTIONS, Query } from '../lib/appwrite'
import { PageHeader, Card, Button, Badge, Tabs, EmptyState, Dialog, Field } from '../components/ui'
import { StatusPill, UrgentPill } from '../components/ui/StatusPill'
import AuftraegeUndRechnungen from '../components/auftraege/AuftraegeUndRechnungen'
import AssignedProjectCard from '../components/AssignedProjectCard'
import CopyableCredential, { getCustomerPortalPassword } from '../components/CopyableCredential'
import { updateCustomerWithPortalAccess, deleteCustomerWithPortalAccess } from '../lib/customerAdminApi'
import { useAuth } from '../context/AuthContext'
import { useWebsiteProjects } from '../hooks/useWebsiteProjects'
import { customerTabs, resolveCustomerTab } from '../lib/customerTabs'
import { isInvoiceReady, setCustomerArchived, upgradeToCustomer, markLost, reopenAsLead } from '../lib/leads'
import { lastRejection } from '../lib/leadDuplicates'
import { KUNDENART_OPTIONEN, KUNDENART_HINWEIS, kundenartAenderung } from '../lib/kundenFelder'
import { customerStage, isArchived, customerBadges, customerEyebrow, customerTitle } from '../lib/customerList'
import { ticketPath, ticketRef } from '../lib/ticketRoutes'
import { ticketNumber } from '../lib/ticketView'
import { isRowActivation } from '../lib/rowClick'
import CustomerViewLog from '../components/customer/CustomerViewLog'
import ChatThread from '../components/chat/ChatThread'
import AboStatusCard from '../components/customer/AboStatusCard'
import CustomerFunktionen from '../components/customer/CustomerFunktionen'
import CreditsView from '../components/credits/CreditsView'
import OffersView from '../components/offers/OffersView'
import KundenansichtButton from '../components/customer/KundenansichtButton'
import { getCustomerPortalStatus } from '../lib/teamApi'
import { formatLastLogin } from '../lib/lastLogin'

const PORTAL_URL = 'https://project.webklar.com'

// Rueckmeldung neben einem Knopf: err und warn mit role="alert", ok ohne
function Msg({ msg }) {
  if (!msg) return null
  return <span className={`msg ${msg.tone}`} role={msg.tone === 'ok' ? undefined : 'alert'}>{msg.text}</span>
}

export default function CustomerDetailPage() {
  const { id } = useParams()
  const [customer, setCustomer] = useState(null)
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState(null)
  // Reiter steht in der Adresse (/customers/<id>?tab=protokoll), damit Sammellisten und Team-Mails direkt hineinspringen
  const [searchParams, setSearchParams] = useSearchParams()
  const tab = searchParams.get('tab') || 'overview'
  const setTab = useCallback(
    (next) => setSearchParams(next === 'overview' ? {} : { tab: next }, { replace: true }),
    [setSearchParams]
  )
  const { isAdmin } = useAuth()
  const navigate = useNavigate()

  const load = useCallback(async () => {
    setLoading(true)
    try {
      setCustomer(await databases.getDocument(DATABASE_ID, COLLECTIONS.CUSTOMERS, id))
      setError(null)
    } catch (err) {
      setError(err.message)
    } finally {
      setLoading(false)
    }
  }, [id])

  useEffect(() => { load() }, [load])

  if (loading) return <div className="page"><div className="loading">Wird geladen …</div></div>
  if (error || !customer) return <div className="page"><EmptyState title="Kunde nicht gefunden" hint={error} action={<Button as={Link} to="/customers">Zurück</Button>} /></div>

  const stage = customerStage(customer)
  // „Rechnungen“ nur für Admins (die Finanzen-API gibt sonst 403); ein nicht erlaubter Reiter fällt auf die Übersicht zurück
  const activeTab = resolveCustomerTab(tab, isAdmin)
  const archived = isArchived(customer)
  const title = customerTitle(customer)

  const toggleArchived = async () => {
    await setCustomerArchived(customer, !archived)
    await load()
  }

  // Loescht Kunde und Portal-Login ueber die Admin-API des Kundenportals (nur Admins)
  const removeCustomer = async () => {
    if (!window.confirm(`${customer.name || customer.email} und den Portal-Zugang wirklich löschen?`)) return
    try {
      await deleteCustomerWithPortalAccess(customer.$id)
      navigate('/customers')
    } catch (err) {
      window.alert(`Löschen fehlgeschlagen: ${err.message}`)
    }
  }

  // Unter dem Namen: Abzeichen (Wichtig, Archiviert; die Stufe steht in der Eyebrow), dann Standort · E-Mail · Telefon
  const badges = customerBadges(customer, { stage: false })
  const contact = [customer.location, customer.email, customer.phone].filter(Boolean).join(' · ')
  const subtitle = badges.length > 0 || contact ? (
    <span className="kunde-sub">
      {badges.map((b) => (
        <Badge key={b.key} tone={b.tone}>{b.label}</Badge>
      ))}
      {contact}
    </span>
  ) : null

  return (
    <div className="page">
      <PageHeader
        crumb={[{ label: 'Kunden', to: '/customers' }, { label: title }]}
        eyebrow={customerEyebrow(customer)}
        title={title}
        subtitle={subtitle}
        actions={
          <>
            {isAdmin && <Button variant="danger" onClick={removeCustomer}>Kunde löschen</Button>}
            <Button onClick={toggleArchived}>{archived ? 'Wiederherstellen' : 'Archivieren'}</Button>
            <KundenansichtButton customer={customer} />
          </>
        }
      />

      <Tabs tabs={customerTabs(isAdmin)} active={activeTab} onChange={setTab} />

      {/* key: nach Absage/Umstufung neu aufbauen, sonst ueberschreibt ein spaeteres Speichern die neuen Notizen */}
      {activeTab === 'overview' && <OverviewTab key={customer.$updatedAt} customer={customer} stage={stage} onSaved={load} />}
      {activeTab === 'tickets' && <CustomerTickets customerId={customer.$id} />}
      {activeTab === 'invoices' && <AuftraegeUndRechnungen key={customer.$id} customer={customer} onShowOverview={() => setTab('overview')} />}
      {activeTab === 'projects' && <CustomerProjects customerId={customer.$id} />}
      {activeTab === 'chat' && <Card><ChatThread customerId={customer.$id} customerName={customer.name} /></Card>}
      {activeTab === 'abo' && (
        <>
          <AboStatusCard customerId={customer.$id} />
          <div className="kunde-abo-angebote"><OffersView customerId={customer.$id} customerName={customer.name} /></div>
        </>
      )}
      {activeTab === 'gutschriften' && <CreditsView customerId={customer.$id} />}
      {activeTab === 'funktionen' && <CustomerFunktionen customerId={customer.$id} />}
      {activeTab === 'protokoll' && <CustomerViewLog customerId={customer.$id} />}
    </div>
  )
}

function OverviewTab({ customer, stage, onSaved }) {
  const [form, setForm] = useState({
    name: customer.name || '',
    companyName: customer.companyName || customer.name || '',
    code: customer.code || '',
    email: customer.email || '',
    phone: customer.phone || '',
    contactName: customer.contactName || '',
    street: customer.street || '',
    postalCode: customer.postalCode || '',
    city: customer.city || '',
    country: customer.country || 'Deutschland',
    vatNumber: customer.vatNumber || '',
    location: customer.location || '',
    notes: customer.notes || '',
    importantCustomer: !!customer.importantCustomer,
  })
  const [kundenart, setKundenart] = useState(customer.kundenart || '')
  const [busy, setBusy] = useState(false)
  const [msg, setMsg] = useState(null) // { tone: 'ok' | 'err' | 'warn', text }
  const [showLost, setShowLost] = useState(false)
  const { user, employee } = useAuth()

  // Die Kundenart geht nur ins Dokument, wenn sie geaendert wurde (kein Fehler bei noch nicht angelegtem Attribut)
  const felder = () => ({ ...form, ...kundenartAenderung(kundenart, customer.kundenart) })

  const ready = isInvoiceReady({ ...customer, ...form })

  // Absage: ungespeicherte Notizen gehen mit, damit der Vermerk nichts ueberschreibt
  const saveLost = async (reason) => {
    await markLost({ ...customer, notes: form.notes }, { reason, by: employee?.displayName || user?.name || '' })
    setShowLost(false)
    onSaved()
  }

  const reopen = async () => {
    setBusy(true); setMsg(null)
    try {
      await reopenAsLead(customer)
      onSaved()
    } catch (err) {
      setMsg({ tone: 'err', text: 'Fehler: ' + err.message })
      setBusy(false)
    }
  }

  const save = async () => {
    setBusy(true); setMsg(null)
    try {
      await databases.updateDocument(DATABASE_ID, COLLECTIONS.CUSTOMERS, customer.$id, felder())
      setMsg({ tone: 'ok', text: 'Gespeichert' })
      onSaved()
    } catch (err) {
      setMsg({ tone: 'err', text: 'Fehler: ' + err.message })
    } finally { setBusy(false) }
  }

  const upgrade = async () => {
    if (!ready) { setMsg({ tone: 'warn', text: 'Bitte zuerst alle Pflichtfelder (Unternehmen, E-Mail, Strasse, PLZ, Stadt) ausfuellen.' }); return }
    setBusy(true); setMsg(null)
    try {
      await upgradeToCustomer(customer, felder())
      setMsg({ tone: 'ok', text: 'Zum festen Kunden gemacht.' })
      onSaved()
    } catch (err) {
      setMsg({ tone: 'err', text: 'Fehler: ' + err.message })
    } finally { setBusy(false) }
  }

  const rejection = lastRejection(customer.notes)

  return (
    <div className="two-col">
      <div>
        {stage === 'lost' && (
          <div className="kunde-absage" role="note">
            <strong>Hat abgesagt – bitte nicht erneut anrufen.</strong>
            {rejection && <div>{rejection}</div>}
            <div className="toolbar">
              <Button onClick={reopen} disabled={busy}>Wieder als Lead führen</Button>
            </div>
          </div>
        )}
        <Card title="Stammdaten">
          <dl className="kv kunde-kv">
            <dt><label htmlFor="kunde-name">Unternehmen / Name</label></dt>
            <dd><input id="kunde-name" className="input" value={form.name} onChange={(e) => setForm({ ...form, name: e.target.value, companyName: e.target.value })} /></dd>
            <dt><label htmlFor="kunde-code">Code</label></dt>
            <dd><input id="kunde-code" className="input" value={form.code} onChange={(e) => setForm({ ...form, code: e.target.value })} /></dd>
            <dt><label htmlFor="kunde-email">E-Mail</label></dt>
            <dd><input id="kunde-email" className="input" type="email" value={form.email} onChange={(e) => setForm({ ...form, email: e.target.value })} /></dd>
            <dt><label htmlFor="kunde-phone">Telefon</label></dt>
            <dd><input id="kunde-phone" className="input" value={form.phone} onChange={(e) => setForm({ ...form, phone: e.target.value })} /></dd>
            <dt><label htmlFor="kunde-location">Standort</label></dt>
            <dd><input id="kunde-location" className="input" value={form.location} onChange={(e) => setForm({ ...form, location: e.target.value })} /></dd>
            <dt><label htmlFor="kunde-contact">Ansprechpartner</label></dt>
            <dd><input id="kunde-contact" className="input" value={form.contactName} onChange={(e) => setForm({ ...form, contactName: e.target.value })} /></dd>
            <dt className="kunde-kv-oben"><label htmlFor="kunde-notes">Notizen</label></dt>
            <dd><textarea id="kunde-notes" className="textarea" rows={3} value={form.notes} onChange={(e) => setForm({ ...form, notes: e.target.value })} /></dd>
          </dl>
          <label className="check">
            <input type="checkbox" checked={form.importantCustomer} onChange={(e) => setForm({ ...form, importantCustomer: e.target.checked })} />
            Wichtiger Kunde
          </label>
          <div className="toolbar">
            <Button variant="primary" onClick={save} disabled={busy}>{busy ? 'Speichert …' : 'Speichern'}</Button>
            {stage === 'lead' && <Button onClick={upgrade} disabled={busy}>Zum festen Kunden machen</Button>}
            {stage === 'lead' && <Button onClick={() => setShowLost(true)} disabled={busy}>Absage eintragen</Button>}
            <Msg msg={msg} />
          </div>
        </Card>
        {showLost && <LostDialog name={customer.name} onCancel={() => setShowLost(false)} onSave={saveLost} />}

        <Card title="Rechnungsdaten">
          {!ready && <div className="kunde-hinweis"><Badge tone="warn">Adresse unvollständig</Badge></div>}
          <dl className="kv kunde-kv">
            <dt><label htmlFor="kunde-kundenart">Kundenart</label></dt>
            <dd>
              <select id="kunde-kundenart" className="select" value={kundenart} onChange={(e) => setKundenart(e.target.value)}>
                {KUNDENART_OPTIONEN.map((o) => <option key={o.value} value={o.value}>{o.label}</option>)}
              </select>
              <div className="hint">{KUNDENART_HINWEIS}</div>
            </dd>
            <dt><label htmlFor="kunde-street">Strasse + Nr.</label></dt>
            <dd><input id="kunde-street" className="input" value={form.street} onChange={(e) => setForm({ ...form, street: e.target.value })} /></dd>
            <dt><label htmlFor="kunde-postal">PLZ</label></dt>
            <dd><input id="kunde-postal" className="input" value={form.postalCode} onChange={(e) => setForm({ ...form, postalCode: e.target.value })} /></dd>
            <dt><label htmlFor="kunde-city">Stadt</label></dt>
            <dd><input id="kunde-city" className="input" value={form.city} onChange={(e) => setForm({ ...form, city: e.target.value })} /></dd>
            <dt><label htmlFor="kunde-country">Land</label></dt>
            <dd><input id="kunde-country" className="input" value={form.country} onChange={(e) => setForm({ ...form, country: e.target.value })} /></dd>
            <dt><label htmlFor="kunde-vat">USt-IdNr.</label></dt>
            <dd><input id="kunde-vat" className="input" value={form.vatNumber} onChange={(e) => setForm({ ...form, vatNumber: e.target.value })} /></dd>
          </dl>
        </Card>
      </div>

      <div>
        <PortalAccessCard customer={customer} onSaved={onSaved} />
      </div>
    </div>
  )
}

// Absage eintragen: Grund ist freiwillig; Datum und Person setzt markLost
function LostDialog({ name, onCancel, onSave }) {
  const [reason, setReason] = useState('')
  const [busy, setBusy] = useState(false)
  const [error, setError] = useState(null)

  const submit = async (e) => {
    e.preventDefault()
    setBusy(true); setError(null)
    try {
      await onSave(reason.trim())
    } catch (err) {
      setError(err.message || 'Fehler')
      setBusy(false)
    }
  }

  return (
    <Dialog
      as="form"
      title={`Absage von ${name || 'diesem Lead'}`}
      busy={busy}
      onClose={onCancel}
      onSubmit={submit}
      footer={
        <>
          <span className="grow" />
          <Button type="button" disabled={busy} onClick={onCancel}>Abbrechen</Button>
          <Button variant="primary" type="submit" disabled={busy}>{busy ? 'Speichert …' : 'Absage speichern'}</Button>
        </>
      }
    >
      {error && <div className="msg err" role="alert">{error}</div>}
      <p className="muted small">
        Der Eintrag wandert in den Reiter „Abgesagt“ und wird beim Anlegen neuer Leads als Warnung angezeigt.
        Offene Akquise-Tickets werden auf „Abgesagt“ gesetzt. Datum und dein Name kommen in die Notizen.
      </p>
      <Field label="Grund (freiwillig)" htmlFor="lost-reason">
        <textarea id="lost-reason" className="textarea" rows={3} value={reason} onChange={(e) => setReason(e.target.value)}
          placeholder="z. B. kein Bedarf, hat schon eine Agentur, nicht vor 2027 melden" />
      </Field>
    </Dialog>
  )
}

function PortalAccessCard({ customer, onSaved }) {
  const [password, setPassword] = useState('')
  const [busy, setBusy] = useState(false)
  const [msg, setMsg] = useState(null) // { tone: 'ok' | 'err' | 'warn', text }

  const hasAccess = Boolean(customer.portalAccessEnabled && customer.appwriteUserId)
  const currentPassword = getCustomerPortalPassword(customer)
  // Letzter Login kommt vom Portal (customerPortalAccess), nicht aus dem Kunden-Dokument
  const [lastLogin, setLastLogin] = useState(undefined)
  useEffect(() => {
    let active = true
    getCustomerPortalStatus(customer.$id)
      .then((status) => active && setLastLogin(status.lastLoginAt || null))
      .catch(() => active && setLastLogin(false))
    return () => { active = false }
  }, [customer.$id])

  const savePassword = async () => {
    if (!customer.email) {
      setMsg({ tone: 'warn', text: 'Bitte zuerst eine E-Mail-Adresse in den Stammdaten speichern.' })
      return
    }
    if (!password || password.length < 8) {
      setMsg({ tone: 'warn', text: 'Das Passwort muss mindestens 8 Zeichen haben.' })
      return
    }
    setBusy(true); setMsg(null)
    try {
      await updateCustomerWithPortalAccess(customer.$id, { password })
      setPassword('')
      setMsg({ tone: 'ok', text: hasAccess ? 'Passwort aktualisiert.' : 'Portal-Zugang angelegt.' })
      onSaved()
    } catch (err) {
      setMsg({ tone: 'err', text: 'Fehler: ' + err.message })
    } finally {
      setBusy(false)
    }
  }

  return (
    <Card title="Portal-Zugang">
      <dl className="kv kunde-kv">
        <dt>Kundenportal</dt>
        <dd>
          {hasAccess
            ? <Badge tone="ok">freigeschaltet</Badge>
            : <Badge tone="muted">kein Zugang</Badge>}
        </dd>
        <dt>Letzter Login</dt>
        <dd>{lastLogin === undefined ? '…' : lastLogin === false ? 'nicht abrufbar' : formatLastLogin(lastLogin)}</dd>
        <dt>Login (E-Mail)</dt>
        <dd><CopyableCredential value={customer.email} label="Login" /></dd>
        <dt>Passwort</dt>
        <dd><CopyableCredential value={currentPassword} secret label="Passwort" /></dd>
        <dt><label htmlFor="kunde-neues-passwort">{hasAccess ? 'Neues Passwort setzen' : 'Passwort festlegen (min. 8 Zeichen)'}</label></dt>
        <dd>
          <input
            id="kunde-neues-passwort"
            className="input"
            type="text"
            value={password}
            onChange={(e) => setPassword(e.target.value)}
            placeholder="min. 8 Zeichen"
            autoComplete="off"
          />
        </dd>
      </dl>

      <div className="toolbar">
        <Button onClick={savePassword} disabled={busy}>
          {busy ? 'Speichert …' : hasAccess ? 'Passwort ändern' : 'Zugang anlegen'}
        </Button>
        <KundenansichtButton customer={customer} />
        <Msg msg={msg} />
      </div>
      <p className="muted small">
        Der Kunde meldet sich mit dieser E-Mail und dem Passwort unter {PORTAL_URL} an
        und sieht dort seine Projekte/Previews.
      </p>
    </Card>
  )
}

function CustomerTickets({ customerId }) {
  const navigate = useNavigate()
  const [tickets, setTickets] = useState([])
  const [loading, setLoading] = useState(true)

  useEffect(() => {
    let active = true
    ;(async () => {
      setLoading(true)
      try {
        const res = await databases.listDocuments(DATABASE_ID, COLLECTIONS.WORKORDERS, [
          Query.equal('customerId', customerId),
          Query.orderDesc('$createdAt'),
          Query.limit(100),
        ])
        if (active) setTickets(res.documents)
      } catch {
        if (active) setTickets([])
      } finally {
        if (active) setLoading(false)
      }
    })()
    return () => { active = false }
  }, [customerId])

  if (loading) return <div className="loading">Wird geladen …</div>
  if (tickets.length === 0) return <EmptyState title="Keine Tickets" hint="Fuer diesen Kunden gibt es noch keine Tickets." />

  return (
    <table className="table">
      <thead>
        <tr>
          <th>Ticket</th>
          <th>Status</th>
        </tr>
      </thead>
      <tbody>
        {tickets.map((t) => {
          const path = ticketPath(ticketRef(t))
          return (
            <tr
              key={t.$id}
              className="row"
              onClick={(e) => {
                if (isRowActivation(e)) navigate(path)
              }}
            >
              <td>
                <div className="cell-title">
                  <Link className="row-link" to={path}>
                    <span className="id">{ticketNumber(t)}</span>
                    <span>{t.topic || t.title || '-'}</span>
                  </Link>
                  <UrgentPill priority={t.priority} />
                </div>
                {t.type && <div className="cell-sub">{t.type}</div>}
              </td>
              <td><StatusPill status={t.status} /></td>
            </tr>
          )
        })}
      </tbody>
    </table>
  )
}

function CustomerProjects({ customerId }) {
  const { fetchAllProjects } = useWebsiteProjects()
  const [projects, setProjects] = useState([])
  const [loading, setLoading] = useState(true)

  useEffect(() => {
    let active = true
    ;(async () => {
      setLoading(true)
      const all = await fetchAllProjects()
      if (active) setProjects((all || []).filter((p) => p.customerId === customerId))
      if (active) setLoading(false)
    })()
    return () => { active = false }
  }, [customerId, fetchAllProjects])

  if (loading) return <div className="loading">Wird geladen …</div>
  if (projects.length === 0) return <Card><EmptyState title="Keine Projekte" hint="Diesem Kunden sind keine Projekte/Previews zugeordnet." /></Card>

  return (
    <Card title={`Projekte (${projects.length})`}>
      {projects.map((p) => <AssignedProjectCard key={p.$id} project={p} />)}
    </Card>
  )
}