import { FormEvent, useCallback, useEffect, useRef, useState } from 'react'
import { FaComment, FaPaperPlane, FaPlus, FaRobot } from 'react-icons/fa'
import { Helmet } from 'react-helmet'
import { useStoreState } from '@/store'
import { Button, Drawer, Dropdown, ScrollBar, Spinner } from '@/components/ui'
import { Container } from '@/components/shared'
import { useLocalization } from '@/utils/hooks/useLocalization'
import { aiService } from '@/services/ai.service'
import { APP_NAME } from '@/constants/app.constant'
import { AI_ASSISTANT } from '@/constants/permission.constant'
import ConversationList from './components/ConversationList'
import MessageBubble from './components/MessageBubble'
import { useAiBots } from './hooks/useAiBots'
import { useConversations } from './hooks/useConversations'

const Assistant = () => {
  const { translate } = useLocalization()
  const { user, tenant } = useStoreState((state) => state.auth)
  const { bots, selectedBot, selectedBotId, setSelectedBotId } = useAiBots()
  const {
    conversations,
    activeConversationId,
    activeConversation,
    messages,
    appendMessage,
    startNewConversation,
    selectConversation,
    deleteConversation,
  } = useConversations()

  const [isConversationDrawerOpen, setIsConversationDrawerOpen] = useState(false)
  const [input, setInput] = useState('')
  const [loading, setLoading] = useState(false)

  const inputRef = useRef<HTMLInputElement | null>(null)
  const bottomRef = useRef<HTMLDivElement | null>(null)
  const requestRef = useRef<AbortController | null>(null)

  // Açık istek varken sayfadan çıkılırsa iptal et.
  useEffect(() => () => requestRef.current?.abort(), [])

  useEffect(() => {
    bottomRef.current?.scrollIntoView({ behavior: 'smooth', block: 'end' })
  }, [messages, loading])

  useEffect(() => {
    if (!loading) inputRef.current?.focus()
  }, [loading])

  const focusInput = () => requestAnimationFrame(() => inputRef.current?.focus())

  const handleNewConversation = useCallback(() => {
    if (loading) return
    startNewConversation()
    setInput('')
    setIsConversationDrawerOpen(false)
    focusInput()
  }, [loading, startNewConversation])

  const handleSelectConversation = useCallback(
    (conversationId: string) => {
      if (loading) return
      selectConversation(conversationId)
      setIsConversationDrawerOpen(false)
      focusInput()
    },
    [loading, selectConversation],
  )

  const handleDeleteConversation = useCallback(
    (conversationId: string) => {
      if (loading) return
      deleteConversation(conversationId)
      if (conversationId === activeConversationId) setInput('')
    },
    [loading, deleteConversation, activeConversationId],
  )

  const handleSubmit = async (event: FormEvent) => {
    event.preventDefault()

    const question = input.trim()
    if (loading || !question || !activeConversation) return

    const conversationId = activeConversation.id
    setInput('')
    setLoading(true)

    appendMessage(conversationId, {
      role: 'user',
      content: question,
      createdAt: new Date().toISOString(),
    })

    const controller = new AbortController()
    requestRef.current = controller

    try {
      if (!selectedBot?.apiUrl?.trim()) {
        throw new Error('AI bot url is not configured.')
      }

      const content = await aiService.askBot(
        selectedBot.apiUrl,
        {
          biletId: conversationId,
          question,
          sessionId: conversationId,
          tenantName: tenant?.tenantName ?? null,
        },
        controller.signal,
      )

      appendMessage(conversationId, {
        role: 'assistant',
        content,
        createdAt: new Date().toISOString(),
      })
    } catch (error) {
      if (controller.signal.aborted) return

      console.error('AI bot request failed:', error)
      appendMessage(conversationId, {
        role: 'assistant',
        content: selectedBot ? translate('::AI.RequestFailed') : translate('::AI.SelectModel'),
        createdAt: new Date().toISOString(),
      })
    } finally {
      if (requestRef.current === controller) {
        requestRef.current = null
        setLoading(false)
      }
    }
  }

  const conversationListProps = {
    conversations,
    activeConversationId,
    disabled: loading,
    onSelect: handleSelectConversation,
    onDelete: handleDeleteConversation,
  }

  return (
    <Container>
      <Helmet
        titleTemplate={`%s | ${APP_NAME}`}
        title={translate('::' + AI_ASSISTANT)}
        defaultTitle={APP_NAME}
      />

      <Drawer
        isOpen={isConversationDrawerOpen}
        placement="left"
        title={translate('::App.Platform.Chats')}
        width={320}
        bodyClass="p-3"
        onClose={() => setIsConversationDrawerOpen(false)}
        onRequestClose={() => setIsConversationDrawerOpen(false)}
      >
        <Button block icon={<FaPlus />} disabled={loading} onClick={handleNewConversation}>
          {translate('::App.Platform.NewChat')}
        </Button>
        <div className="mt-3 max-h-[calc(100vh-140px)] overflow-y-auto overscroll-contain">
          <ConversationList {...conversationListProps} />
        </div>
      </Drawer>

      <div className="h-[calc(100vh-140px)] pt-2 flex gap-4">
        <aside className="hidden w-64 shrink-0 flex-col rounded-xl border border-gray-200 bg-white p-3 dark:border-gray-700 dark:bg-gray-800 lg:flex">
          <Button block icon={<FaPlus />} disabled={loading} onClick={handleNewConversation}>
            {translate('::App.Platform.NewChat')}
          </Button>
          <ScrollBar autoHide className="mt-3 flex-1 min-h-0">
            <div className="pr-2">
              <ConversationList {...conversationListProps} />
            </div>
          </ScrollBar>
        </aside>

        <div className="min-w-0 flex flex-1 flex-col">
          <div className="mb-2 flex shrink-0 gap-2 lg:hidden">
            <Button
              className="flex-1"
              size="sm"
              icon={<FaPlus />}
              disabled={loading}
              onClick={handleNewConversation}
            >
              {translate('::App.Platform.NewChat')}
            </Button>
            <Button
              className="flex-1"
              size="sm"
              icon={<FaComment />}
              onClick={() => setIsConversationDrawerOpen(true)}
            >
              {translate('::App.Platform.Chats')}
            </Button>
          </div>

          <ScrollBar
            autoHide
            hideTracksWhenNotNeeded
            autoHideTimeout={700}
            autoHideDuration={200}
            className="flex-1 min-h-0 min-w-0"
            renderView={({ style, ...props }) => (
              <div {...props} style={{ ...style, overflowX: 'hidden' }} />
            )}
            renderThumbVertical={({ style, ...props }) => (
              <div
                {...props}
                className="rounded-full bg-gray-300/80 dark:bg-gray-600/80"
                style={{ ...style, width: 6, right: 3 }}
              />
            )}
          >
            <div className="p-4 space-y-4">
              {messages.length === 0 && (
                <div className="text-center text-gray-500 dark:text-gray-400 mt-8">
                  <FaRobot className="w-12 h-12 mx-auto mb-4 text-gray-400 dark:text-gray-500" />
                  <p className="mt-2">{translate('::AI.Welcome')}</p>
                  <p className="text-lg font-medium">{translate('::AI.Name')}</p>
                </div>
              )}

              {messages.map((message, index) => (
                <MessageBubble
                  key={`${activeConversationId}-${index}`}
                  message={message}
                  avatar={user?.avatar}
                />
              ))}

              {loading && (
                <div className="flex items-center gap-2 text-sm text-gray-500 dark:text-gray-400">
                  <Spinner size={20} />
                  <span>{translate('::AI.WaitAnswer')}</span>
                </div>
              )}

              <div ref={bottomRef} />
            </div>
          </ScrollBar>

          <form className="w-full mx-auto px-4" onSubmit={handleSubmit}>
            <div className="flex w-full items-center gap-2 rounded-2xl bg-[#2a2a2a] px-3 py-2 text-white shadow-md">
              <input
                ref={inputRef}
                autoFocus
                value={input}
                disabled={loading}
                placeholder={translate('::AI.Asking')}
                className="min-w-0 flex-1 bg-transparent px-1 text-base outline-none placeholder-gray-400 disabled:cursor-not-allowed"
                onChange={(event) => setInput(event.target.value)}
              />

              <div className="shrink-0 text-sm">
                <Dropdown
                  placement="top-end"
                  menuClass="w-48 max-w-[calc(100vw-2rem)]"
                  toggleClassName="[&_svg]:ml-2"
                  title={selectedBot?.name || translate('::AI.SelectModel')}
                >
                  {bots.map((item) => (
                    <Dropdown.Item
                      key={item.id}
                      eventKey={item.id}
                      onSelect={(eventKey: string) => setSelectedBotId(eventKey)}
                    >
                      {item.name}
                    </Dropdown.Item>
                  ))}
                </Dropdown>
              </div>

              <div className="ml-2 flex shrink-0 items-center border-l border-white/15 pl-3">
                <Button
                  size="sm"
                  shape="circle"
                  variant="plain"
                  type="submit"
                  icon={<FaPaperPlane />}
                  disabled={loading || !input.trim() || !selectedBotId}
                  className="bg-white !text-gray-800 shadow-sm hover:bg-gray-100"
                />
              </div>
            </div>
          </form>
        </div>
      </div>
    </Container>
  )
}

export default Assistant