"use client";

import {
  forwardRef,
  useCallback,
  useRef,
  useState,
  type ReactElement,
} from "react";
import { ArrowDown, ThumbsDown, ThumbsUp } from "lucide-react";

import { cn } from "@/lib/utils";
import { useAutoScroll } from "@/hooks/use-auto-scroll";
import { Button } from "@/components/ui/button";
import { type Message } from "@/components/chat-playground/chat-message";
import { CopyButton } from "@/components/ui/copy-button";
import { MessageInput } from "@/components/chat-playground/message-input";
import { MessageList } from "@/components/chat-playground/message-list";
import { PromptSuggestions } from "@/components/chat-playground/prompt-suggestions";

interface ChatPropsBase {
  handleSubmit: (
    event?: { preventDefault?: () => void },
    options?: { experimental_attachments?: FileList }
  ) => void;
  messages: Array<Message>;
  input: string;
  className?: string;
  handleInputChange: React.ChangeEventHandler<HTMLTextAreaElement>;
  isGenerating: boolean;
  stop?: () => void;
  onRateResponse?: (
    messageId: string,
    rating: "thumbs-up" | "thumbs-down"
  ) => void;
  setMessages?: (messages: Message[]) => void;
  transcribeAudio?: (blob: Blob) => Promise<string>;
}

interface ChatPropsWithoutSuggestions extends ChatPropsBase {
  append?: never;
  suggestions?: never;
}

interface ChatPropsWithSuggestions extends ChatPropsBase {
  append: (message: { role: "user"; content: string }) => void;
  suggestions: string[];
}

type ChatProps = ChatPropsWithoutSuggestions | ChatPropsWithSuggestions;

export function Chat({
  messages,
  handleSubmit,
  input,
  handleInputChange,
  stop,
  isGenerating,
  append,
  suggestions,
  className,
  onRateResponse,
  setMessages,
  transcribeAudio,
}: ChatProps) {
  const lastMessage = messages.at(-1);
  const isEmpty = messages.length === 0;
  const isTyping = lastMessage?.role === "user";

  const messagesRef = useRef(messages);
  messagesRef.current = messages;

  // Enhanced stop function that marks pending tool calls as cancelled
  const handleStop = useCallback(() => {
    stop?.();

    if (!setMessages) return;

    const latestMessages = [...messagesRef.current];
    const lastAssistantMessage = latestMessages.findLast(
      m => m.role === "assistant"
    );

    if (!lastAssistantMessage) return;

    let needsUpdate = false;
    let updatedMessage = { ...lastAssistantMessage };

    if (lastAssistantMessage.toolInvocations) {
      const updatedToolInvocations = lastAssistantMessage.toolInvocations.map(
        toolInvocation => {
          if (toolInvocation.state === "call") {
            needsUpdate = true;
            return {
              ...toolInvocation,
              state: "result",
              result: {
                content: "Tool execution was cancelled",
                __cancelled: true, // Special marker to indicate cancellation
              },
            } as const;
          }
          return toolInvocation;
        }
      );

      if (needsUpdate) {
        updatedMessage = {
          ...updatedMessage,
          toolInvocations: updatedToolInvocations,
        };
      }
    }

    if (lastAssistantMessage.parts && lastAssistantMessage.parts.length > 0) {
      const updatedParts = lastAssistantMessage.parts.map(
        (part: {
          type: string;
          toolInvocation?: { state: string; toolName: string };
        }) => {
          if (
            part.type === "tool-invocation" &&
            part.toolInvocation &&
            part.toolInvocation.state === "call"
          ) {
            needsUpdate = true;
            return {
              ...part,
              toolInvocation: {
                ...part.toolInvocation,
                state: "result",
                result: {
                  content: "Tool execution was cancelled",
                  __cancelled: true,
                },
              },
            };
          }
          return part;
        }
      );

      if (needsUpdate) {
        updatedMessage = {
          ...updatedMessage,
          parts: updatedParts,
        };
      }
    }

    if (needsUpdate) {
      const messageIndex = latestMessages.findIndex(
        m => m.id === lastAssistantMessage.id
      );
      if (messageIndex !== -1) {
        latestMessages[messageIndex] = updatedMessage;
        setMessages(latestMessages);
      }
    }
  }, [stop, setMessages, messagesRef]);

  const messageOptions = useCallback(
    (message: Message) => ({
      actions: onRateResponse ? (
        <>
          <div className="border-r pr-1">
            <CopyButton
              content={message.content}
              copyMessage="Copied response to clipboard!"
            />
          </div>
          <Button
            size="icon"
            variant="ghost"
            className="h-6 w-6"
            onClick={() => onRateResponse(message.id, "thumbs-up")}
          >
            <ThumbsUp className="h-4 w-4" />
          </Button>
          <Button
            size="icon"
            variant="ghost"
            className="h-6 w-6"
            onClick={() => onRateResponse(message.id, "thumbs-down")}
          >
            <ThumbsDown className="h-4 w-4" />
          </Button>
        </>
      ) : (
        <CopyButton
          content={message.content}
          copyMessage="Copied response to clipboard!"
        />
      ),
    }),
    [onRateResponse]
  );

  return (
    <ChatContainer className={className}>
      <div className="flex-1 flex flex-col">
        {isEmpty && append && suggestions ? (
          <div className="flex-1 flex items-center justify-center">
            <PromptSuggestions
              label="Try these prompts ✨"
              append={append}
              suggestions={suggestions}
            />
          </div>
        ) : null}

        {messages.length > 0 ? (
          <ChatMessages messages={messages}>
            <MessageList
              messages={messages}
              isTyping={isTyping}
              messageOptions={messageOptions}
            />
          </ChatMessages>
        ) : null}
      </div>

      <div className="mt-auto border-t bg-background/95 backdrop-blur supports-[backdrop-filter]:bg-background/60">
        <div className="container max-w-4xl py-4">
          <ChatForm
            isPending={isGenerating || isTyping}
            handleSubmit={handleSubmit}
          >
            {({ files, setFiles }) => (
              <MessageInput
                value={input}
                onChange={handleInputChange}
                allowAttachments
                files={files}
                setFiles={setFiles}
                stop={handleStop}
                isGenerating={isGenerating}
                transcribeAudio={transcribeAudio}
              />
            )}
          </ChatForm>
        </div>
      </div>
    </ChatContainer>
  );
}
Chat.displayName = "Chat";

export function ChatMessages({
  messages,
  children,
}: React.PropsWithChildren<{
  messages: Message[];
}>) {
  const {
    containerRef,
    scrollToBottom,
    handleScroll,
    shouldAutoScroll,
    handleTouchStart,
  } = useAutoScroll([messages]);

  return (
    <div
      className="grid grid-cols-1 overflow-y-auto pb-4"
      ref={containerRef}
      onScroll={handleScroll}
      onTouchStart={handleTouchStart}
    >
      <div className="max-w-full [grid-column:1/1] [grid-row:1/1]">
        {children}
      </div>

      {!shouldAutoScroll && (
        <div className="pointer-events-none flex flex-1 items-end justify-end [grid-column:1/1] [grid-row:1/1]">
          <div className="sticky bottom-0 left-0 flex w-full justify-end">
            <Button
              onClick={scrollToBottom}
              className="pointer-events-auto h-8 w-8 rounded-full ease-in-out animate-in fade-in-0 slide-in-from-bottom-1"
              size="icon"
              variant="ghost"
            >
              <ArrowDown className="h-4 w-4" />
            </Button>
          </div>
        </div>
      )}
    </div>
  );
}

export const ChatContainer = forwardRef<
  HTMLDivElement,
  React.HTMLAttributes<HTMLDivElement>
>(({ className, ...props }, ref) => {
  return (
    <div
      ref={ref}
      className={cn("flex flex-col max-h-full w-full", className)}
      {...props}
    />
  );
});
ChatContainer.displayName = "ChatContainer";

interface ChatFormProps {
  className?: string;
  isPending: boolean;
  handleSubmit: (
    event?: { preventDefault?: () => void },
    options?: { experimental_attachments?: FileList }
  ) => void;
  children: (props: {
    files: File[] | null;
    setFiles: React.Dispatch<React.SetStateAction<File[] | null>>;
  }) => ReactElement;
}

export const ChatForm = forwardRef<HTMLFormElement, ChatFormProps>(
  ({ children, handleSubmit, isPending, className }, ref) => {
    const [files, setFiles] = useState<File[] | null>(null);

    const onSubmit = (event: React.FormEvent) => {
      if (isPending) {
        event.preventDefault();
        return;
      }

      if (!files) {
        handleSubmit(event);
        return;
      }

      const fileList = createFileList(files);
      handleSubmit(event, { experimental_attachments: fileList });
      setFiles(null);
    };

    return (
      <form ref={ref} onSubmit={onSubmit} className={className}>
        {children({ files, setFiles })}
      </form>
    );
  }
);
ChatForm.displayName = "ChatForm";

function createFileList(files: File[] | FileList): FileList {
  const dataTransfer = new DataTransfer();
  for (const file of Array.from(files)) {
    dataTransfer.items.add(file);
  }
  return dataTransfer.files;
}