/**
 * Domains — the inline rules that override the downloaded lists.
 *
 * The table is server-paged, so every filter change rewinds to page 1 and the
 * query object is memoised so `useApi` only refetches when something the
 * server cares about actually changed.
 */

import { useEffect, useMemo, useState } from 'react'
import type { ReactNode } from 'react'
import { Plus, Search, Trash2 } from 'lucide-react'

import { addDomain, deleteDomain, getDomains } from '../lib/api'
import type { AddDomainInput } from '../lib/api'
import type { DomainItem } from '../lib/types'
import { useApi, useAsyncAction } from '../hooks/useApi'
import { useDebounced } from '../hooks/useDebounced'
import { formatNumber, formatRelative, toLines } from '../lib/format'
import {
  Badge,
  Button,
  Card,
  ConfirmDialog,
  Dialog,
  EmptyState,
  IconButton,
  Input,
  Pagination,
  Select,
  Table,
  Textarea,
  useToast,
} from '../components/ui'
import type { ToastOptions } from '../components/ui'
import { PageError, PageHeader } from '../components/layout'

type Row = Record<string, ReactNode>

/**
 * One line for every mutation on this page: the message plus the tone it
 * earned. `fail` is the danger tone, `ok` the success one.
 */
function notify(
  toast: (options: ToastOptions) => void,
  kind: 'ok' | 'fail',
  message: string,
): void {
  toast({ title: message, tone: kind === 'ok' ? 'ok' : 'danger' })
}

const PER_PAGE = 50

const ACTIONS = [
  { value: 'block', label: 'Block (NXDOMAIN)' },
  { value: 'allow', label: 'Allow (pass through)' },
  { value: 'drop', label: 'Drop (no response)' },
  { value: 'nxdomain', label: 'NXDOMAIN' },
  { value: 'redirect', label: 'Redirect' },
]

const NAME_HINT =
  '*.example.com matches subdomains, **.example.com matches the apex too, a bare name matches exactly.'

function actionTone(action: string): 'default' | 'ok' | 'warn' | 'danger' | 'info' | 'muted' {
  switch (action) {
    case 'allow':
      return 'ok'
    case 'block':
      return 'warn'
    case 'drop':
      return 'danger'
    case 'nxdomain':
      return 'warn'
    case 'redirect':
      return 'info'
    default:
      return 'default'
  }
}

type AddForm = {
  name: string
  action: string
  list: string
  bulk: string
  advanced: boolean
}

const EMPTY_FORM: AddForm = { name: '', action: 'block', list: '', bulk: '', advanced: false }

export default function Domains() {
  const { toast } = useToast()
  const [search, setSearch] = useState('')
  const [action, setAction] = useState('')
  const [list, setList] = useState('')
  const [page, setPage] = useState(1)
  const q = useDebounced(search, 300)

  const [addOpen, setAddOpen] = useState(false)
  const [form, setForm] = useState<AddForm>(EMPTY_FORM)
  const [formError, setFormError] = useState<string | null>(null)
  const [pendingDelete, setPendingDelete] = useState<DomainItem | null>(null)

  // A new filter makes the old page number meaningless.
  useEffect(() => {
    setPage(1)
  }, [q, action, list])

  const filters = useMemo(
    () => ({
      q: q.trim(),
      action: action === '' ? undefined : action,
      list: list === '' ? undefined : list,
      page,
      per_page: PER_PAGE,
    }),
    [q, action, list, page],
  )

  const { data, error, loading, refetch } = useApi(() => getDomains(filters), [filters])

  const items: DomainItem[] = useMemo(() => data?.items ?? [], [data])
  const total = data?.total ?? items.length

  const add = useAsyncAction(async (input: AddDomainInput) => addDomain(input))
  const remove = useAsyncAction(async (name: string, act: string, src: string) =>
    deleteDomain(name, act, src),
  )

  const lists = useMemo(() => {
    const seen = new Set<string>()
    for (const item of items) {
      if (item.list) seen.add(item.list)
      if (item.source) seen.add(item.source)
    }
    return Array.from(seen).sort()
  }, [items])

  const bulkLines = useMemo(() => toLines(form.bulk), [form.bulk])
  const canSubmit =
    form.action !== '' && (form.bulk.trim() !== '' || form.name.trim() !== '')

  const submit = async (): Promise<void> => {
    setFormError(null)
    if (!canSubmit) {
      setFormError('enter a domain, or paste rules in the bulk box')
      return
    }
    if (form.bulk.trim() !== '') {
      for (const line of bulkLines) {
        const allow = line.startsWith('!')
        const ruleName = allow ? line.slice(1).trim() : line
        if (ruleName === '') continue
        const res = await add.run({
          name: ruleName,
          action: allow ? 'allow' : form.action,
          list: form.list.trim() || undefined,
          source: 'console',
          content: '',
        })
        if (res === null) {
          notify(toast, 'fail', add.error ?? `could not add ${ruleName}`)
          return
        }
      }
      notify(toast, 'ok', `added ${bulkLines.length} rule${bulkLines.length === 1 ? '' : 's'}`)
    } else {
      const res = await add.run({
        name: form.name.trim(),
        action: form.action,
        list: form.list.trim() || undefined,
        source: 'console',
        content: '',
      })
      if (res === null) {
        setFormError(add.error ?? 'the server rejected that rule')
        notify(toast, 'fail', add.error ?? 'could not add the rule')
        return
      }
      notify(toast, 'ok', `added ${form.name.trim()}`)
    }
    setForm(EMPTY_FORM)
    setAddOpen(false)
    refetch()
  }

  const confirmDelete = async (): Promise<void> => {
    const target = pendingDelete
    if (!target) return
    const res = await remove.run(target.name, String(target.action), target.list || target.source)
    if (res === null) {
      notify(toast, 'fail', remove.error ?? `could not delete ${target.name}`)
      return
    }
    setPendingDelete(null)
    notify(toast, 'ok', `deleted ${target.name}`)
    refetch()
  }

  if (error) return <PageError error={error} onRetry={refetch} />

  const columns = [
    { key: 'name', header: 'Domain', width: '40%' },
    { key: 'action', header: 'Action', width: '16%' },
    { key: 'source', header: 'List', width: '20%' },
    { key: 'hits', header: 'Hits', width: '10%', align: 'right' as const },
    { key: 'updated', header: 'Updated', width: '10%' },
    { key: 'delete', header: '', width: '4%', align: 'right' as const },
  ]

  const rows: Row[] = items.map((item, i) => ({
    __key: `${item.name}-${item.action}-${item.list}-${i}`,
    name: <span className="block max-w-[320px] truncate font-mono text-xs">{item.name}</span>,
    action: <Badge tone={actionTone(String(item.action))}>{item.action}</Badge>,
    source: (
      <span className="block max-w-[200px] truncate text-xs text-slate-500 dark:text-slate-400">
        {item.list || item.source || '—'}
      </span>
    ),
    hits: <span className="font-mono text-xs">{formatNumber(item.hits)}</span>,
    updated: <span className="whitespace-nowrap text-xs">{formatRelative(item.updated_at)}</span>,
    delete: (
      <IconButton
        icon={Trash2}
        label={`delete ${item.name}`}
        variant="ghost"
        onClick={() => setPendingDelete(item)}
      />
    ),
  }))

  return (
    <div className="space-y-4">
      <PageHeader
        title="Domains"
        description="Inline allow and block rules, checked before the downloaded lists."
        actions={
          <Button icon={Plus} onClick={() => setAddOpen(true)}>
            Add rule
          </Button>
        }
      />

      <Card>
        <div className="grid grid-cols-1 gap-3 sm:grid-cols-3">
          <Input
            label="Search"
            placeholder="ads.example.com"
            icon={Search}
            value={search}
            onChange={(e) => setSearch(e.target.value)}
            autoComplete="off"
            spellCheck={false}
          />
          <Select
            label="Action"
            value={action}
            onChange={(e) => setAction(e.target.value)}
            options={[{ value: '', label: 'All actions' }, ...ACTIONS.map((a) => ({ value: a.value, label: a.label }))]}
          />
          <Select
            label="List"
            value={list}
            onChange={(e) => setList(e.target.value)}
            options={[{ value: '', label: 'All lists' }, ...lists.map((l) => ({ value: l, label: l }))]}
          />
        </div>
      </Card>

      <Card
        title="Rules"
        subtitle={`${formatNumber(total)} matching`}
        padded={false}
      >
        <div className="overflow-x-auto">
          <Table
            columns={columns}
            rows={rows}
            rowKey={(row) => String(row.__key)}
            loading={loading}
            empty={
              <EmptyState
                title="No rules match"
                description="Change the filters, or add a rule with the button above."
              />
            }
          />
        </div>
        <div className="border-t border-slate-200 p-3 dark:border-slate-800">
          <Pagination page={page} perPage={PER_PAGE} total={total} onPage={setPage} />
        </div>
      </Card>

      <Dialog
        open={addOpen}
        onClose={() => setAddOpen(false)}
        title="Add a rule"
        description="Rules are checked before the blocklists, so an allow rule wins over a block."
        footer={
          <div className="flex justify-end gap-2">
            <Button variant="ghost" onClick={() => setAddOpen(false)} disabled={add.pending}>
              Cancel
            </Button>
            <Button onClick={() => void submit()} loading={add.pending} disabled={!canSubmit}>
              {bulkLines.length > 0 ? `Add ${bulkLines.length} rules` : 'Add rule'}
            </Button>
          </div>
        }
      >
        <div className="space-y-3">
          {formError ? (
            <p className="rounded-md bg-red-500/10 px-3 py-2 text-sm text-red-700 dark:text-red-300">
              {formError}
            </p>
          ) : null}
          <Input
            label="Domain"
            placeholder="ads.example.com"
            hint={NAME_HINT}
            value={form.name}
            onChange={(e) => setForm((f) => ({ ...f, name: e.target.value }))}
            disabled={form.advanced}
            autoComplete="off"
            spellCheck={false}
          />
          <div className="grid grid-cols-1 gap-3 sm:grid-cols-2">
            <Select
              label="Action"
              value={form.action}
              onChange={(e) => setForm((f) => ({ ...f, action: e.target.value }))}
              options={ACTIONS.map((a) => ({ value: a.value, label: a.label }))}
            />
            <Input
              label="List"
              placeholder="inline"
              hint="Optional group name, defaults to the inline list."
              value={form.list}
              onChange={(e) => setForm((f) => ({ ...f, list: e.target.value }))}
              autoComplete="off"
            />
          </div>
          <button
            type="button"
            className="text-xs font-medium text-sky-600 underline-offset-2 hover:underline dark:text-sky-400"
            onClick={() => setForm((f) => ({ ...f, advanced: !f.advanced }))}
          >
            {form.advanced ? 'Hide bulk paste' : 'Bulk paste'}
          </button>
          {form.advanced ? (
            <Textarea
              label="Rules"
              hint={`One per line; a leading ! makes it an allow rule. ${bulkLines.length} line${bulkLines.length === 1 ? '' : 's'} parsed.`}
              monospace
              rows={8}
              value={form.bulk}
              onChange={(e) => setForm((f) => ({ ...f, bulk: e.target.value }))}
              spellCheck={false}
            />
          ) : null}
        </div>
      </Dialog>

      <ConfirmDialog
        open={pendingDelete !== null}
        onClose={() => setPendingDelete(null)}
        onConfirm={() => void confirmDelete()}
        title="Delete this rule?"
        message={
          pendingDelete
            ? `${pendingDelete.name} (${pendingDelete.action}) will be removed and the change persisted to the configuration file.`
            : ''
        }
        confirmLabel="Delete"
        destructive
        pending={remove.pending}
      />
    </div>
  )
}