"use client";

import { useState, useCallback } from "react";

interface Message {
  role: "user" | "assistant";
  content: string;
}

export function useClaudeChat(campaignId: string) {
  const [messages, setMessages] = useState<Message[]>([]);
  const [isStreaming, setIsStreaming] = useState(false);
  const [sessionId, setSessionId] = useState<string | null>(null);

  const sendMessage = useCallback(
    async (content: string) => {
      const userMessage: Message = { role: "user", content };
      setMessages((prev) => [...prev, userMessage]);
      setIsStreaming(true);

      const assistantMessage: Message = { role: "assistant", content: "" };
      setMessages((prev) => [...prev, assistantMessage]);

      try {
        const res = await fetch("/api/claude", {
          method: "POST",
          headers: { "Content-Type": "application/json" },
          body: JSON.stringify({
            message: content,
            sessionId,
            campaignId,
          }),
        });

        if (!res.ok || !res.body) {
          setMessages((prev) => {
            const updated = [...prev];
            updated[updated.length - 1] = {
              role: "assistant",
              content: "Failed to get response from Claude.",
            };
            return updated;
          });
          setIsStreaming(false);
          return;
        }

        const reader = res.body.getReader();
        const decoder = new TextDecoder();

        let buffer = "";

        while (true) {
          const { done, value } = await reader.read();
          if (done) break;

          buffer += decoder.decode(value, { stream: true });
          const lines = buffer.split("\n");
          buffer = lines.pop() || "";

          for (const line of lines) {
            if (!line.startsWith("data: ")) continue;
            try {
              const data = JSON.parse(line.slice(6));
              if (data.done) continue;
              if (data.text) {
                setMessages((prev) => {
                  const updated = [...prev];
                  const last = updated[updated.length - 1];
                  updated[updated.length - 1] = {
                    ...last,
                    content: last.content + data.text,
                  };
                  return updated;
                });
              }
              if (data.sessionId) {
                setSessionId(data.sessionId);
              }
            } catch {
              // skip malformed lines
            }
          }
        }
      } catch {
        setMessages((prev) => {
          const updated = [...prev];
          updated[updated.length - 1] = {
            role: "assistant",
            content: "Connection error. Please try again.",
          };
          return updated;
        });
      }

      setIsStreaming(false);
    },
    [campaignId, sessionId]
  );

  return { messages, sendMessage, isStreaming };
}