'use client'

import PageHeading from '../../ui/PageHeading'

import { useRouter } from 'next/navigation'
import { useEffect, useMemo, useState } from 'react'
import { authFetch, clearToken, getApiBase, getToken } from '../../lib/auth'

type ProfileInfo = { username: string; role: string; invite_management_enabled?: boolean }
type OwnedInvite = {
  id: number; code: string; label?: string | null; description?: string | null
  recipient_email?: string | null; max_uses?: number | null; use_count: number
  remaining_uses?: number | null; enabled: boolean; expires_at?: string | null
  is_usable?: boolean; created_at?: string | null
}
type OwnedInvitesResponse = {
  invites?: OwnedInvite[]
  invite_access?: { enabled?: boolean; managed_by_master?: boolean }
  master_invite?: { id: number; code: string; label?: string | null; max_uses?: number | null; expires_at?: string | null } | null
}
type InviteForm = {
  code: string; label: string; description: string; recipient_email: string
  enabled: boolean; message: string
}
type DeliveryMethod = '' | 'manual' | 'email'

const defaultInviteForm = (): InviteForm => ({
  code: '', label: '', description: '', recipient_email: '', enabled: true, message: '',
})
const formatDate = (value?: string | null) => {
  if (!value) return 'Never'
  const date = new Date(value)
  return Number.isNaN(date.valueOf()) ? value : date.toLocaleString()
}
const isValidEmail = (value: string) => /^[^\s@]+@[^\s@]+\.[^\s@]+$/.test(value.trim())

export default function ProfileInvitesPage() {
  const router = useRouter()
  const [profile, setProfile] = useState<ProfileInfo | null>(null)
  const [invites, setInvites] = useState<OwnedInvite[]>([])
  const [inviteAccessEnabled, setInviteAccessEnabled] = useState(false)
  const [inviteManagedByMaster, setInviteManagedByMaster] = useState(false)
  const [masterInvite, setMasterInvite] = useState<OwnedInvitesResponse['master_invite']>(null)
  const [loading, setLoading] = useState(true)
  const [saving, setSaving] = useState(false)
  const [error, setError] = useState<string | null>(null)
  const [status, setStatus] = useState<string | null>(null)
  const [editingId, setEditingId] = useState<number | null>(null)
  const [flowStep, setFlowStep] = useState(1)
  const [useCustomCode, setUseCustomCode] = useState(false)
  const [deliveryMethod, setDeliveryMethod] = useState<DeliveryMethod>('')
  const [inviteForm, setInviteForm] = useState<InviteForm>(defaultInviteForm())
  const [createdInvite, setCreatedInvite] = useState<OwnedInvite | null>(null)

  const signupBaseUrl = useMemo(() => {
    if (typeof window === 'undefined') return '/signup'
    return `${window.location.origin}/signup`
  }, [])

  const loadInvites = async () => {
    const response = await authFetch(`${getApiBase()}/auth/profile/invites`)
    if (!response.ok) {
      if (response.status === 401) {
        clearToken()
        router.push('/login')
        return
      }
      throw new Error('Could not load your invite workspace.')
    }
    const data = (await response.json()) as OwnedInvitesResponse
    setInvites(Array.isArray(data.invites) ? data.invites : [])
    setInviteAccessEnabled(Boolean(data.invite_access?.enabled))
    setInviteManagedByMaster(Boolean(data.invite_access?.managed_by_master))
    setMasterInvite(data.master_invite ?? null)
  }

  useEffect(() => {
    if (!getToken()) {
      router.push('/login')
      return
    }
    const load = async () => {
      try {
        const profileResponse = await authFetch(`${getApiBase()}/auth/profile`)
        if (!profileResponse.ok) {
          if (profileResponse.status === 401) {
            clearToken()
            router.push('/login')
            return
          }
          throw new Error('Could not load your profile.')
        }
        const profileData = await profileResponse.json()
        setProfile(profileData?.user ?? null)
        await loadInvites()
      } catch (err) {
        console.error(err)
        setError(err instanceof Error ? err.message : 'Could not load your invite workspace.')
      } finally {
        setLoading(false)
      }
    }
    void load()
  }, [router])

  const resetFlow = () => {
    setEditingId(null)
    setFlowStep(1)
    setUseCustomCode(false)
    setDeliveryMethod('')
    setInviteForm(defaultInviteForm())
  }

  const editInvite = (invite: OwnedInvite) => {
    setEditingId(invite.id)
    setCreatedInvite(null)
    setFlowStep(4)
    setUseCustomCode(true)
    setDeliveryMethod(invite.recipient_email ? 'email' : 'manual')
    setInviteForm({
      code: invite.code,
      label: invite.label ?? '',
      description: invite.description ?? '',
      recipient_email: invite.recipient_email ?? '',
      enabled: invite.enabled !== false,
      message: '',
    })
    setError(null)
    setStatus(null)
    window.scrollTo({ top: 0, behavior: 'smooth' })
  }

  const saveInvite = async (event: React.FormEvent) => {
    event.preventDefault()
    const inviteName = inviteForm.label.trim()
    const recipientEmail = inviteForm.recipient_email.trim()
    if (!inviteName) {
      setError('Give this invite a name so you can recognise it later.')
      return
    }
    if (!deliveryMethod) {
      setError('Choose how you want to deliver the invite.')
      return
    }
    if (deliveryMethod === 'email' && !isValidEmail(recipientEmail)) {
      setError('Enter a valid recipient email address.')
      return
    }
    setSaving(true)
    setError(null)
    setStatus(null)
    try {
      const response = await authFetch(
        editingId == null ? `${getApiBase()}/auth/profile/invites` : `${getApiBase()}/auth/profile/invites/${editingId}`,
        {
          method: editingId == null ? 'POST' : 'PUT',
          headers: { 'Content-Type': 'application/json' },
          body: JSON.stringify({
            code: useCustomCode ? inviteForm.code || null : null,
            label: inviteName,
            description: inviteForm.description || null,
            recipient_email: deliveryMethod === 'email' ? recipientEmail : null,
            enabled: inviteForm.enabled,
            send_email: editingId == null && deliveryMethod === 'email',
            message: inviteForm.message || null,
          }),
        }
      )
      if (!response.ok) {
        if (response.status === 401) {
          clearToken()
          router.push('/login')
          return
        }
        throw new Error((await response.text()) || 'Could not save the invite.')
      }
      const data = await response.json()
      const savedInvite = data?.invite as OwnedInvite | undefined
      setStatus(
        data?.email?.status === 'ok'
          ? `Invite created and emailed to ${data.email.recipient_email}.`
          : data?.email?.status === 'error'
            ? `Invite created, but the email could not be sent: ${data.email.detail}`
            : editingId == null ? 'Invite link created and ready to share.' : 'Invite updated.'
      )
      resetFlow()
      if (editingId == null && savedInvite) setCreatedInvite(savedInvite)
      await loadInvites()
    } catch (err) {
      console.error(err)
      setError(err instanceof Error ? err.message : 'Could not save the invite.')
    } finally {
      setSaving(false)
    }
  }

  const deleteInvite = async (invite: OwnedInvite) => {
    if (!window.confirm(`Delete invite “${invite.label || invite.code}”?`)) return
    setError(null)
    try {
      const response = await authFetch(`${getApiBase()}/auth/profile/invites/${invite.id}`, { method: 'DELETE' })
      if (!response.ok) throw new Error((await response.text()) || 'Could not delete the invite.')
      if (editingId === invite.id) resetFlow()
      setStatus(`Deleted ${invite.label || invite.code}.`)
      await loadInvites()
    } catch (err) {
      console.error(err)
      setError(err instanceof Error ? err.message : 'Could not delete the invite.')
    }
  }

  const copyInviteLink = async (invite: OwnedInvite) => {
    const url = `${signupBaseUrl}?code=${encodeURIComponent(invite.code)}`
    try {
      await navigator.clipboard.writeText(url)
      setStatus(`Copied the link for ${invite.label || invite.code}.`)
    } catch {
      window.prompt('Copy invite link', url)
    }
  }

  const codeCharacters = inviteForm.code.replace(/[^a-z0-9]/gi, '')
  const identityReady = Boolean(inviteForm.label.trim() && (!useCustomCode || codeCharacters.length >= 6))
  const canManageInvites = profile?.role === 'admin' || inviteAccessEnabled
  const createdInviteUrl = createdInvite ? `${signupBaseUrl}?code=${encodeURIComponent(createdInvite.code)}` : ''

  if (loading) return <main className="card">Loading invite workspace…</main>

  return (
    <main className="card invites-page">
      <PageHeading title="Invites" description="Invite someone to Grizzlyflix and manage the links you share." />
      {error && <div className="error-banner">{error}</div>}
      {status && <div className="status-banner">{status}</div>}

      {!canManageInvites ? (
        <section className="profile-section profile-tab-panel">
          <h2>Invites are not enabled for your account</h2>
          <p className="lede">Ask an administrator if you need permission to invite someone.</p>
        </section>
      ) : (
        <section className="profile-section profile-invites-section profile-tab-panel">
          <div className="invite-flow-heading">
            <div><span className="eyebrow">Invite flow</span><h2>{editingId == null ? 'Create an invite' : `Edit ${inviteForm.label || 'invite'}`}</h2><p className="lede">Set up the invite one decision at a time.</p></div>
            {editingId != null && <button type="button" className="ghost-button" onClick={resetFlow}>Cancel edit</button>}
          </div>

          {createdInvite && editingId == null ? (
            <div className="invite-created-card" role="status">
              <span className="eyebrow">Invite ready</span><h3>{createdInvite.label || 'Your invite'}</h3>
              <p>{createdInvite.recipient_email ? `The invite was emailed to ${createdInvite.recipient_email}.` : 'Copy this link and send it to the person you are inviting.'}</p>
              <div className="invite-created-link"><input value={createdInviteUrl} readOnly aria-label="Created invite link" /><button type="button" onClick={() => void copyInviteLink(createdInvite)}>Copy link</button></div>
              <button type="button" className="ghost-button" onClick={() => { setCreatedInvite(null); resetFlow() }}>Create another invite</button>
            </div>
          ) : (
            <form onSubmit={saveInvite} className="invite-flow-form">
              <ol className="invite-flow-route" aria-label="Invite creation progress">
                {['Identity', 'Description', 'Access', 'Delivery'].map((label, index) => {
                  const step = index + 1
                  return <li key={label} className={step === flowStep ? 'is-active' : step < flowStep ? 'is-complete' : ''}><span>{String(step).padStart(2, '0')}</span><strong>{label}</strong></li>
                })}
              </ol>

              <section className={`invite-flow-step ${flowStep > 1 ? 'is-complete' : 'is-active'}`}>
                <header><span className="invite-flow-number">01</span><div><span className="eyebrow">Identity</span><h3>Who is this invite for?</h3><p>Give it a name that will make sense when you return later.</p></div></header>
                <div className="invite-flow-fields">
                  <label><span>Invite name</span><input value={inviteForm.label} onChange={(event) => setInviteForm((current) => ({ ...current, label: event.target.value }))} placeholder="Family, that guy from work, the neighbour" /></label>
                  <label className="invite-flow-choice-line"><input type="checkbox" checked={useCustomCode} disabled={editingId != null} onChange={(event) => { setUseCustomCode(event.target.checked); if (!event.target.checked) setInviteForm((current) => ({ ...current, code: '' })) }} /><span><strong>Choose a custom invite code</strong><small>The code appears at the end of the sign-up link. Leave this off and Magent will create a secure code for you.</small></span></label>
                  {useCustomCode && <label><span>Custom code</span><input value={inviteForm.code} disabled={editingId != null} onChange={(event) => setInviteForm((current) => ({ ...current, code: event.target.value }))} placeholder="At least 6 letters or numbers" /><small>This becomes <code>/signup?code={inviteForm.code || 'YOUR-CODE'}</code>.</small></label>}
                  {flowStep === 1 && <div className="invite-flow-actions"><button type="button" disabled={!identityReady} onClick={() => setFlowStep(2)}>Continue to description</button></div>}
                </div>
              </section>

              {flowStep >= 2 && <section className={`invite-flow-step ${flowStep > 2 ? 'is-complete' : 'is-active'}`}>
                <header><span className="invite-flow-number">02</span><div><span className="eyebrow">Description</span><h3>Add a welcome note</h3><p>This optional message is shown on the sign-up page.</p></div></header>
                <div className="invite-flow-fields"><label><span>Welcome note (optional)</span><textarea rows={3} value={inviteForm.description} onChange={(event) => setInviteForm((current) => ({ ...current, description: event.target.value }))} placeholder="Welcome to Grizzlyflix. Use this link to create your account." /></label>{flowStep === 2 && <div className="invite-flow-actions"><button type="button" className="ghost-button" onClick={() => setFlowStep(1)}>Back</button><button type="button" className="ghost-button" onClick={() => { setInviteForm((current) => ({ ...current, description: '' })); setFlowStep(3) }}>Skip</button><button type="button" onClick={() => setFlowStep(3)}>Continue</button></div>}</div>
              </section>}

              {flowStep >= 3 && <section className={`invite-flow-step ${flowStep > 3 ? 'is-complete' : 'is-active'}`}>
                <header><span className="invite-flow-number">03</span><div><span className="eyebrow">Access</span><h3>Account access is applied automatically</h3><p>Magent uses the safe invite policy configured by an administrator.</p></div></header>
                <div className="invite-flow-fields"><div className="invite-policy-note"><strong>Standard user access</strong><span>{inviteManagedByMaster && masterInvite ? `Using the “${masterInvite.label || masterInvite.code}” invite policy. Usage and expiry limits are automatic.` : 'This invite creates a standard user account using your configured defaults.'}</span></div>{flowStep === 3 && <div className="invite-flow-actions"><button type="button" className="ghost-button" onClick={() => setFlowStep(2)}>Back</button><button type="button" onClick={() => setFlowStep(4)}>Continue to delivery</button></div>}</div>
              </section>}

              {flowStep >= 4 && <section className="invite-flow-step is-active">
                <header><span className="invite-flow-number">04</span><div><span className="eyebrow">Delivery</span><h3>How will they receive it?</h3><p>Copy the link yourself, or let Magent email it directly.</p></div></header>
                <div className="invite-flow-fields">
                  <div className="invite-delivery-grid"><button type="button" className={deliveryMethod === 'manual' ? 'is-selected' : ''} onClick={() => { setDeliveryMethod('manual'); setInviteForm((current) => ({ ...current, recipient_email: '', message: '' })) }}><span className="eyebrow">Manual</span><strong>Give me a link</strong><small>Magent creates the URL. You copy and share it yourself.</small></button><button type="button" className={deliveryMethod === 'email' ? 'is-selected' : ''} onClick={() => setDeliveryMethod('email')}><span className="eyebrow">Email</span><strong>Send it for me</strong><small>Magent emails the invitation and still gives you a copyable URL.</small></button></div>
                  {deliveryMethod === 'manual' && <div className="invite-delivery-summary"><strong>Your link will appear as soon as the invite is created.</strong><span>No email address is required and Magent will not send a message.</span></div>}
                  {deliveryMethod === 'email' && <div className="invite-flow-field-grid"><label><span>Recipient email</span><input type="email" value={inviteForm.recipient_email} onChange={(event) => setInviteForm((current) => ({ ...current, recipient_email: event.target.value }))} placeholder="person@example.com" /></label><label><span>Email note (optional)</span><textarea rows={3} value={inviteForm.message} onChange={(event) => setInviteForm((current) => ({ ...current, message: event.target.value }))} placeholder="A short personal message" /></label></div>}
                  {editingId != null && <label className="invite-status-control"><input type="checkbox" checked={inviteForm.enabled} onChange={(event) => setInviteForm((current) => ({ ...current, enabled: event.target.checked }))} /><span><strong>{inviteForm.enabled ? 'Invite enabled' : 'Invite disabled'}</strong><small>Disable this existing invite to stop its link from accepting sign-ups.</small></span></label>}
                  <div className="invite-flow-actions"><button type="button" className="ghost-button" onClick={() => setFlowStep(3)}>Back</button><button type="submit" disabled={saving || !deliveryMethod || (deliveryMethod === 'email' && !isValidEmail(inviteForm.recipient_email))}>{saving ? 'Saving…' : editingId != null ? 'Save invite' : deliveryMethod === 'email' ? 'Create and email invite' : 'Create invite link'}</button></div>
                </div>
              </section>}
            </form>
          )}

          <div className="profile-invites-list">
            <div className="invite-flow-heading"><div><span className="eyebrow">Your invites</span><h2>Created invites</h2><p className="lede">Copy, edit, disable, or remove invitations you have made.</p></div></div>
            {invites.length === 0 ? <div className="status-banner">You have not created any invites yet.</div> : <div className="admin-list">{invites.map((invite) => <div key={invite.id} className="admin-list-item"><div className="admin-list-item-main"><div className="admin-list-item-title-row"><strong>{invite.label || 'Unnamed invite'}</strong><code className="invite-code">{invite.code}</code><span className={`small-pill ${invite.is_usable ? '' : 'is-muted'}`}>{invite.is_usable ? 'Ready' : 'Unavailable'}</span></div>{invite.description && <p className="admin-list-item-text admin-list-item-text--muted">{invite.description}</p>}<div className="admin-meta-row"><span>Delivery: {invite.recipient_email || 'Manual link'}</span><span>Uses: {invite.use_count}{typeof invite.max_uses === 'number' ? ` / ${invite.max_uses}` : ''}</span><span>Expires: {formatDate(invite.expires_at)}</span><span>Created: {formatDate(invite.created_at)}</span></div></div><div className="admin-inline-actions"><button type="button" className="ghost-button" onClick={() => void copyInviteLink(invite)}>Copy link</button><button type="button" className="ghost-button" onClick={() => editInvite(invite)}>Edit</button><button type="button" onClick={() => void deleteInvite(invite)}>Delete</button></div></div>)}</div>}
          </div>
        </section>
      )}
    </main>
  )
}