'use client'

import type OpenAI from 'openai'
import {
  Dispatch,
  SetStateAction,
  useCallback,
  useEffect,
  useReducer,
  useRef,
  useState,
} from 'react'

import { SSE } from 'sse.js'

import {
  AiIconAnimation,
  Button,
  IconCornerDownLeft,
  IconUser,
  Input,
  markdownComponents,
} from 'ui'
import { AiIconChat } from './Command.icons'
import { CommandGroup, CommandItem, useAutoInputFocus, useHistoryKeys } from './Command.utils'

import { AiWarning } from './Command.alerts'
import { useCommandMenu } from './CommandMenuContext'

import ReactMarkdown from 'react-markdown'
import remarkGfm from 'remark-gfm'
import { cn } from 'ui/src/lib/utils'
import { StatusIcon } from '../Icons/StatusIcons'
import { isBrowser } from 'common'

const questions = [
  'How do I get started with Supabase?',
  'How do I run Supabase locally?',
  'How do I connect to my database?',
  'How do I run migrations? ',
  'How do I listen to changes in a table?',
  'How do I set up authentication?',
]

export const BASE_PATH = process.env.NEXT_PUBLIC_BASE_PATH ?? ''

export enum MessageRole {
  User = 'user',
  Assistant = 'assistant',
}

export enum MessageStatus {
  Pending = 'pending',
  InProgress = 'in-progress',
  Complete = 'complete',
}

export interface Message {
  role: MessageRole
  content: string
  status: MessageStatus
}

interface NewMessageAction {
  type: 'new'
  message: Message
}

interface UpdateMessageAction {
  type: 'update'
  index: number
  message: Partial<Message>
}

interface AppendContentAction {
  type: 'append-content'
  index: number
  content: string
}

interface ResetAction {
  type: 'reset'
}

type MessageAction = NewMessageAction | UpdateMessageAction | AppendContentAction | ResetAction

function messageReducer(state: Message[], messageAction: MessageAction) {
  let current = [...state]
  const { type } = messageAction

  switch (type) {
    case 'new': {
      const { message } = messageAction
      current.push(message)
      break
    }
    case 'update': {
      const { index, message } = messageAction
      if (current[index]) {
        Object.assign(current[index], message)
      }
      break
    }
    case 'append-content': {
      const { index, content } = messageAction
      if (current[index]) {
        current[index].content += content
      }
      break
    }
    case 'reset': {
      current = []
      break
    }
    default: {
      throw new Error(`Unknown message action '${type}'`)
    }
  }

  return current
}

export interface UseAiChatOptions {
  messageTemplate?: (message: string) => string
  setIsLoading?: Dispatch<SetStateAction<boolean>>
}

export function useAiChat({
  messageTemplate = (message) => message,
  setIsLoading,
}: UseAiChatOptions) {
  const eventSourceRef = useRef<SSE>()

  const [isResponding, setIsResponding] = useState(false)
  const [hasError, setHasError] = useState(false)

  const [currentMessageIndex, setCurrentMessageIndex] = useState(1)
  const [messages, dispatchMessage] = useReducer(messageReducer, [])

  const submit = useCallback(
    async (query: string) => {
      dispatchMessage({
        type: 'new',
        message: {
          status: MessageStatus.Complete,
          role: MessageRole.User,
          content: query,
        },
      })
      dispatchMessage({
        type: 'new',
        message: {
          status: MessageStatus.Pending,
          role: MessageRole.Assistant,
          content: '',
        },
      })
      setIsResponding(false)
      setHasError(false)
      setIsLoading?.(true)

      const eventSource = new SSE(`${BASE_PATH}/api/ai/docs`, {
        headers: {
          apikey: process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY ?? '',
          Authorization: `Bearer ${process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY}`,
          'Content-Type': 'application/json',
        },
        payload: JSON.stringify({
          messages: messages
            .filter(({ status }) => status === MessageStatus.Complete)
            .map(({ role, content }) => ({ role, content }))
            .concat({ role: MessageRole.User, content: messageTemplate(query) }),
        }),
      })

      function handleError<T>(err: T) {
        setIsLoading?.(false)
        setIsResponding(false)
        setHasError(true)
        console.error(err)
      }

      eventSource.addEventListener('error', handleError)
      eventSource.addEventListener('message', (e: MessageEvent) => {
        try {
          setIsLoading?.(false)

          if (e.data === '[DONE]') {
            setIsResponding(false)
            dispatchMessage({
              type: 'update',
              index: currentMessageIndex,
              message: {
                status: MessageStatus.Complete,
              },
            })
            setCurrentMessageIndex((x) => x + 2)
            return
          }

          dispatchMessage({
            type: 'update',
            index: currentMessageIndex,
            message: {
              status: MessageStatus.InProgress,
            },
          })

          setIsResponding(true)

          const completionChunk: OpenAI.Chat.Completions.ChatCompletionChunk = JSON.parse(e.data)
          const [
            {
              delta: { content },
            },
          ] = completionChunk.choices

          if (content) {
            dispatchMessage({
              type: 'append-content',
              index: currentMessageIndex,
              content,
            })
          }
        } catch (err) {
          handleError(err)
        }
      })

      eventSource.stream()

      eventSourceRef.current = eventSource

      setIsLoading?.(true)
    },
    [currentMessageIndex, messages, messageTemplate]
  )

  function reset() {
    eventSourceRef.current?.close()
    eventSourceRef.current = undefined
    setIsResponding(false)
    setHasError(false)
    dispatchMessage({
      type: 'reset',
    })
  }

  return {
    submit,
    reset,
    messages,
    isResponding,
    hasError,
  }
}

/**
 * Perform a one-off query to AI based on a snapshot of messages
 */
export function queryAi(messages: Message[], timeout = 0) {
  return new Promise<string>((resolve, reject) => {
    const eventSource = new SSE(`${BASE_PATH}/api/ai/docs`, {
      headers: {
        apikey: process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY ?? '',
        Authorization: `Bearer ${process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY}`,
        'Content-Type': 'application/json',
      },
      payload: JSON.stringify({
        messages: messages.map(({ role, content }) => ({ role, content })),
      }),
    })

    let timeoutId: number | undefined

    function handleError<T>(err: T) {
      if (timeoutId) {
        clearTimeout(timeoutId)
      }
      console.error(err)
      reject(err)
    }

    if (timeout > 0) {
      timeoutId = window.setTimeout(() => {
        handleError(new Error('AI query timed out'))
      }, timeout)
    }

    let answer = ''

    eventSource.addEventListener('error', handleError)
    eventSource.addEventListener('message', (e: MessageEvent) => {
      try {
        if (e.data === '[DONE]') {
          if (timeoutId) {
            clearTimeout(timeoutId)
          }
          resolve(answer)
          return
        }

        const completionChunk: OpenAI.Chat.Completions.ChatCompletionChunk = JSON.parse(e.data)
        const [
          {
            delta: { content },
          },
        ] = completionChunk.choices

        if (content) {
          answer += content
        }
      } catch (err) {
        handleError(err)
      }
    })

    eventSource.stream()
  })
}

const AiCommand = () => {
  const { isLoading, setIsLoading, search, setSearch } = useCommandMenu()
  const isMobile = isBrowser && window.screen.width <= 640

  const { submit, reset, messages, isResponding, hasError } = useAiChat({
    setIsLoading,
  })

  /**
   * Disable autofocusing on the input on mobile
   * since it messes up with the dialog height and positioning
   * */
  const inputRef = useAutoInputFocus(!isMobile)

  useHistoryKeys({
    enable: !isResponding,
    messages: messages
      .filter(({ role }) => role === MessageRole.User)
      .map(({ content }) => content),
    setPrompt: setSearch,
  })

  const handleSubmit = useCallback(
    (message: string) => {
      setSearch('')
      submit(message)
    },
    [submit]
  )

  const handleReset = useCallback(() => {
    setSearch('')
    reset()
  }, [reset])

  useEffect(() => {
    if (search) {
      handleSubmit(search)
    }
  }, [])
  // Detect an IME composition (so that we can ignore Enter keypress)
  const [isImeComposing, setIsImeComposing] = useState(false)
  const showSubmitButton = !isLoading && !isResponding && search

  return (
    <div onClick={(e) => e.stopPropagation()}>
      <div className="absolute z-10 top-[45px] md:top-auto md:bottom-0 w-full bg-background pt-2 md:pt-0 md:pb-2">
        <Input
          className={cn(
            'bg-alternative rounded mx-3 [&_input]:text-base [&_input]:placeholder:text-sm',
            showSubmitButton && '[&_input]:pr-32 md:[&_input]:pr-40'
          )}
          inputRef={inputRef}
          autoFocus={!isMobile}
          placeholder={
            isLoading || isResponding ? 'Waiting on an answer...' : 'Ask Supabase AI a question...'
          }
          value={search}
          actions={
            <>
              {showSubmitButton ? (
                <Button
                  onClick={() => {
                    if (!search || isLoading || isResponding || isImeComposing) {
                      return
                    }
                    return handleSubmit(search)
                  }}
                  className={`flex items-center mr-3 ${search ? 'opacity-100' : 'opacity-0'}`}
                  iconRight={
                    <div className="hidden md:flex">
                      <IconCornerDownLeft size={12} strokeWidth={1.5} />
                    </div>
                  }
                >
                  Submit message
                </Button>
              ) : null}
            </>
          }
          onChange={(e) => {
            if (!isLoading || !isResponding) {
              setSearch(e.target.value)
            }
          }}
          onCompositionStart={() => setIsImeComposing(true)}
          onCompositionEnd={() => setIsImeComposing(false)}
          onKeyDown={(e) => {
            switch (e.key) {
              case 'Enter':
                if (!search || isLoading || isResponding || isImeComposing) {
                  return
                }
                return handleSubmit(search)
              default:
                return
            }
          }}
        />
      </div>
      <div className="pt-14 md:pt-0">
        {messages.length > 0 && !hasError && <AiWarning className="mt-2 mx-3 px-3" />}
        <div className={cn('relative py-3')}>
          {!hasError &&
            messages.map((message, index) => {
              switch (message.role) {
                case MessageRole.User:
                  return (
                    <div key={index} className="flex gap-3 mx-4 [overflow-anchor:none] mb-6">
                      <div
                        className="
                  w-7 h-7 bg-background rounded-full border border-muted flex items-center justify-center text-foreground-lighter first-letter:
                  ring-background
                  ring-1
                  shadow-sm
              "
                      >
                        <IconUser strokeWidth={1.5} size={16} />
                      </div>
                      <div className="prose text-foreground-lighter">{message.content}</div>
                    </div>
                  )
                case MessageRole.Assistant:
                  return (
                    <div key={index} className="px-4 pb-8 [overflow-anchor:none] mb-[25px]">
                      <div className="flex gap-4 [overflow-anchor:none] mb-6">
                        <AiIconChat
                          loading={
                            message.status === MessageStatus.Pending ||
                            message.status === MessageStatus.InProgress
                          }
                        />
                        <>
                          {message.status === MessageStatus.Pending ? (
                            <div className="bg-border-strong h-[21px] w-[13px] mt-1 animate-pulse"></div>
                          ) : (
                            <ReactMarkdown
                              remarkPlugins={[remarkGfm]}
                              components={{
                                ...markdownComponents,
                                a: (props) => (
                                  <a {...props} target="_blank" rel="noopener noreferrer" />
                                ),
                              }}
                              className="prose dark:prose-dark"
                              urlTransform={(href: string) => {
                                const supabaseUrl = new URL('https://supabase.com')
                                const linkUrl = new URL(href, 'https://supabase.com')

                                if (linkUrl.origin === supabaseUrl.origin) {
                                  return linkUrl.toString()
                                }

                                return href
                              }}
                            >
                              {message.content}
                            </ReactMarkdown>
                          )}
                        </>
                      </div>
                    </div>
                  )
              }
            })}

          {messages.length === 0 && !hasError && (
            <CommandGroup heading="Examples">
              {questions.map((question) => {
                const key = question.replace(/\s+/g, '_')
                return (
                  <CommandItem
                    type="command"
                    onSelect={() => {
                      if (!search) {
                        handleSubmit(question)
                      }
                    }}
                    key={key}
                  >
                    <AiIconAnimation />
                    {question}
                  </CommandItem>
                )
              })}
            </CommandGroup>
          )}
          {hasError && (
            <div className="p-6 flex flex-col items-center gap-2 mt-4">
              <StatusIcon variant="warning" />
              <div>
                <p className="text-sm text-foreground text-center">
                  Sorry, looks like Supabase AI is having a hard time!
                </p>
                <p className="text-sm text-foreground-lighter text-center">
                  Please try again in a bit.
                </p>
              </div>
              <Button size="tiny" type="default" onClick={handleReset}>
                Try again?
              </Button>
            </div>
          )}

          <div className="[overflow-anchor:auto] h-px w-full"></div>
        </div>
      </div>
    </div>
  )
}

export default AiCommand