import { Loader2, Plus } from 'lucide-react'
import { useEffect, useMemo, useState } from 'react'
import { Link, useNavigate } from 'react-router-dom'
import { waTemplateApi, whatsappApi, type WaManagedTemplate, type WhatsAppAccount } from '../../lib/api'

const STATUS_LABEL: Record<string, string> = {
  APPROVED: 'Approved',
  PENDING: 'Pending',
  REJECTED: 'Rejected',
  PAUSED: 'Paused',
  DISABLED: 'Disabled',
  IN_APPEAL: 'In appeal',
}

function statusLabel(status: string) {
  return STATUS_LABEL[status] || status.toLowerCase()
}

export function WhatsAppTemplatesPage() {
  const navigate = useNavigate()
  const [accounts, setAccounts] = useState<WhatsAppAccount[]>([])
  const [accountId, setAccountId] = useState('')
  const [rows, setRows] = useState<WaManagedTemplate[]>([])
  const [summary, setSummary] = useState({ total: 0, approved: 0, pending: 0, rejected: 0, paused: 0 })
  const [warnings, setWarnings] = useState<string[]>([])
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState('')
  const [guidelines, setGuidelines] = useState(false)
  const [search, setSearch] = useState('')
  const [category, setCategory] = useState('')
  const [language, setLanguage] = useState('')
  const [status, setStatus] = useState('')
  const [from, setFrom] = useState('')
  const [to, setTo] = useState('')

  function load(nextAccount = accountId) {
    setLoading(true)
    setError('')
    waTemplateApi.list(nextAccount || undefined)
      .then((payload) => {
        setRows(payload.templates)
        setSummary(payload.summary)
        setWarnings(payload.warnings)
      })
      .catch((reason) => setError(reason instanceof Error ? reason.message : 'Templates could not be loaded'))
      .finally(() => setLoading(false))
  }

  useEffect(() => {
    whatsappApi.accounts()
      .then(setAccounts)
      .catch(() => setAccounts([]))
    load('')
    // The first load is intentionally unfiltered.
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, [])

  const filtered = useMemo(() => rows.filter((row) => {
    const haystack = `${row.name} ${row.meta_template_id || ''} ${(row.phones || []).join(' ')} ${row.display_phone || ''} ${row.connection_name || ''} ${row.account_name || ''}`.toLowerCase()
    if (search && !haystack.includes(search.toLowerCase())) return false
    if (category && row.category !== category) return false
    if (language && row.language !== language) return false
    if (status && row.status !== status) return false
    const updated = row.updated_at?.slice(0, 10)
    if (from && updated < from) return false
    if (to && updated > to) return false
    return true
  }), [rows, search, category, language, status, from, to])

  const languages = [...new Set(rows.map((row) => row.language))].sort()
  const cards = [
    ['Total templates', summary.total],
    ['Approved', summary.approved],
    ['Pending review', summary.pending],
    ['Rejected', summary.rejected],
    ['Paused', summary.paused],
  ] as const

  async function remove(row: WaManagedTemplate) {
    if (!window.confirm(`Delete ${row.name}? Meta removes it from this WhatsApp account.`)) return
    try {
      await waTemplateApi.remove(row.id)
      load()
    } catch (reason) {
      setError(reason instanceof Error ? reason.message : 'This template could not be deleted')
    }
  }

  return (
    <div className="wa-tpl">
      <div className="account-heading wa-tpl-heading">
        <div>
          <span className="eyebrow">Communicate</span>
          <h1>Message templates</h1>
          <p>Create, manage, and monitor your WhatsApp message templates.</p>
        </div>
        <div className="wa-tpl-heading-actions">
          <button type="button" className="secondary-button" onClick={() => setGuidelines((open) => !open)}>Template guidelines</button>
          <Link className="primary-button" to="/console/whatsapp/templates/new"><Plus size={16} /> Create template</Link>
        </div>
      </div>

      {guidelines && (
        <section className="wa-biz-card wa-tpl-guidelines">
          <h2>Template guidelines</h2>
          <ul>
            <li>Marketing is for offers and announcements. Utility is for an existing order or account. Authentication is only for one-time codes.</li>
            <li>Names use lowercase letters, numbers, and underscores, and must be unique on the WhatsApp account for that language.</li>
            <li>Meta reviews every template. A template stays pending until Meta approves it, and Meta can change the category.</li>
            <li>Templates belong to the WhatsApp Business account, so every number on that account can use an approved template.</li>
          </ul>
        </section>
      )}

      {error && <p className="auth-error">{error}</p>}
      {warnings.map((warning) => <p className="auth-error" key={warning}>{warning}</p>)}

      <div className="wa-tpl-cards">
        {cards.map(([label, value]) => (
          <article key={label}>
            <span>{label}</span>
            <strong>{value}</strong>
          </article>
        ))}
      </div>

      <section className="wa-biz-card">
        <div className="wa-tpl-filters">
          <input value={search} onChange={(event) => setSearch(event.target.value)} placeholder="Search by name or ID" aria-label="Search templates" />
          <select value={accountId} onChange={(event) => { setAccountId(event.target.value); load(event.target.value) }} aria-label="WhatsApp account">
            <option value="">All accounts</option>
            {accounts.filter((account) => account.status !== 'disconnected').map((account) => {
              const numbers = account.phones.map((phone) => phone.display_phone).filter(Boolean).join(', ')
              return <option key={account.id} value={account.id}>{numbers ? `${account.name} · ${numbers}` : account.name}</option>
            })}
          </select>
          <select value={category} onChange={(event) => setCategory(event.target.value)} aria-label="Category">
            <option value="">Category</option>
            <option value="MARKETING">Marketing</option>
            <option value="UTILITY">Utility</option>
            <option value="AUTHENTICATION">Authentication</option>
          </select>
          <select value={language} onChange={(event) => setLanguage(event.target.value)} aria-label="Language">
            <option value="">Language</option>
            {languages.map((item) => <option key={item} value={item}>{item}</option>)}
          </select>
          <select value={status} onChange={(event) => setStatus(event.target.value)} aria-label="Status">
            <option value="">Status</option>
            {Object.entries(STATUS_LABEL).map(([value, label]) => <option key={value} value={value}>{label}</option>)}
          </select>
          <input type="date" value={from} onChange={(event) => setFrom(event.target.value)} aria-label="Updated from" />
          <input type="date" value={to} onChange={(event) => setTo(event.target.value)} aria-label="Updated to" />
        </div>

        {loading && <div className="auth-loading"><Loader2 size={16} className="wa-spin" /> Loading templates…</div>}
        {!loading && accounts.length === 0 && <p>Connect a WhatsApp number before creating templates. <Link to="/console/whatsapp">Open WhatsApp</Link></p>}
        {!loading && accounts.length > 0 && filtered.length === 0 && <p>{rows.length === 0 ? 'No templates yet. Create one and Meta will review it.' : 'No templates match these filters.'}</p>}

        {!loading && filtered.length > 0 && (
          <div className="wa-tpl-table">
            <div className="wa-tpl-row wa-tpl-head">
              <span>Template name</span><span>Number</span><span>Connection</span><span>Category</span><span>Language</span><span>Status</span><span>Quality</span><span>Messages sent</span><span>Last updated</span><span>Actions</span>
            </div>
            {filtered.map((row) => (
              <div className="wa-tpl-row" key={row.id}>
                <button type="button" className="wa-tpl-name" onClick={() => navigate(`/console/whatsapp/templates/${row.id}`)}>{row.name}</button>
                <span className="wa-tpl-number">{(row.phones && row.phones.length ? row.phones : [row.display_phone]).filter(Boolean).join(', ') || 'Shared on the account'}</span>
                <span className="wa-tpl-connection"><strong>{row.connection_name || row.account_name}</strong><small>{row.connection_method}</small></span>
                <span>{row.category.toLowerCase()}</span>
                <span>{row.language}</span>
                <span className={`wa-tpl-status is-${row.status.toLowerCase()}`}>{statusLabel(row.status)}</span>
                <span>{row.quality || '—'}</span>
                <span>{row.messages_sent}</span>
                <span>{row.updated_at ? new Date(row.updated_at).toLocaleDateString() : '—'}</span>
                <span className="wa-tpl-actions">
                  <button type="button" onClick={() => navigate(`/console/whatsapp/templates/${row.id}`)}>View</button>
                  {['REJECTED', 'PAUSED', 'APPROVED'].includes(row.status) && <button type="button" onClick={() => navigate(`/console/whatsapp/templates/${row.id}/edit`)}>Edit</button>}
                  <button type="button" onClick={() => navigate(`/console/whatsapp/templates/new?duplicate=${row.id}`)}>Duplicate</button>
                  <button type="button" onClick={() => void remove(row)}>Delete</button>
                </span>
              </div>
            ))}
          </div>
        )}
      </section>
    </div>
  )
}