"use client";

import { useLayoutEffect, useRef } from "react";
import { useChat } from "@ai-sdk/react";
import { AlertTriangle, Bot, Loader2, User } from "lucide-react";

import { Button } from "@/components/ui/button";
import { cn } from "@/lib/utils";
import { WorkspaceComposer } from "./workspace-composer";
import { createChatScrollMemory } from "./workspace-interaction";

export function ChatMode({
  workspaceSlug,
  active,
}: {
  workspaceSlug: string;
  active: boolean;
}) {
  const scrollRef = useRef<HTMLDivElement>(null);
  const inputRef = useRef<HTMLTextAreaElement>(null);
  const scrollMemory = useRef(createChatScrollMemory());
  const { messages, input, handleSubmit, status, error, setInput, stop } =
    useChat({
      api: "/api/chat",
      body: { workspace: workspaceSlug },
    });
  const isBusy = status === "submitted" || status === "streaming";

  useLayoutEffect(() => {
    const container = scrollRef.current;
    if (container) scrollMemory.current.update(container, active);
  }, [messages, status, active]);

  return (
    <div className="flex h-full min-h-0 flex-col">
      <div
        ref={scrollRef}
        onScroll={(event) => {
          scrollMemory.current.record(event.currentTarget, active);
        }}
        className="min-h-0 flex-1 overflow-y-auto"
      >
        {messages.length === 0 ? (
          <div className="flex h-full min-h-[12rem] flex-col items-center justify-center gap-4 px-4 text-muted-foreground">
            <div className="flex h-16 w-16 items-center justify-center rounded-2xl bg-primary/10">
              <Bot className="size-8 text-primary" aria-hidden="true" />
            </div>
            <div className="text-center">
              <p className="text-base font-medium">How can I help you today?</p>
              <p className="mt-1 text-sm">
                Ask me to break down a task, draft an outline, or summarize what
                you have open.
              </p>
            </div>
            <div className="mt-2 flex flex-wrap justify-center gap-2">
              {[
                "Break this project into subtasks",
                "Summarize my open tasks",
                "Draft a sprint plan for this week",
              ].map((suggestion) => (
                <Button
                  key={suggestion}
                  type="button"
                  variant="outline"
                  size="sm"
                  disabled={isBusy}
                  onClick={() => {
                    setInput(suggestion);
                    inputRef.current?.focus();
                  }}
                  className="h-auto rounded-full px-3 py-1.5 text-xs"
                >
                  {suggestion}
                </Button>
              ))}
            </div>
          </div>
        ) : (
          <div
            role="log"
            aria-label="Chat messages"
            aria-live="polite"
            className="mx-auto max-w-3xl space-y-4 px-4 py-6"
          >
            {messages.map((msg) => (
              <div
                key={msg.id}
                className={cn(
                  "flex gap-3",
                  msg.role === "user" && "flex-row-reverse",
                )}
              >
                <div
                  className={cn(
                    "flex h-7 w-7 shrink-0 items-center justify-center rounded-full",
                    msg.role === "user"
                      ? "bg-primary text-primary-foreground"
                      : "bg-muted",
                  )}
                >
                  {msg.role === "user" ? (
                    <User className="size-3.5" aria-hidden="true" />
                  ) : (
                    <Bot className="size-3.5" aria-hidden="true" />
                  )}
                </div>
                <div
                  className={cn(
                    "max-w-[85%] rounded-xl px-4 py-3 text-sm leading-relaxed",
                    msg.role === "user"
                      ? "bg-primary text-primary-foreground"
                      : "bg-muted",
                  )}
                >
                  <span className="sr-only">
                    {msg.role === "user" ? "You" : "Assistant"}:{" "}
                  </span>
                  <p className="whitespace-pre-wrap break-words">
                    {msg.content}
                  </p>
                </div>
              </div>
            ))}
            {isBusy && messages[messages.length - 1]?.role === "user" && (
              <div role="status" className="flex gap-3">
                <div className="flex h-7 w-7 shrink-0 items-center justify-center rounded-full bg-muted">
                  <Bot className="size-3.5" aria-hidden="true" />
                </div>
                <div className="rounded-xl bg-muted px-4 py-3">
                  <Loader2
                    className="size-4 animate-spin text-muted-foreground"
                    aria-hidden="true"
                  />
                  <span className="sr-only">Generating response…</span>
                </div>
              </div>
            )}
          </div>
        )}
        {error && (
          <div role="alert" className="mx-auto max-w-3xl px-4 pb-4">
            <div className="flex items-start gap-2 rounded-lg border border-destructive/30 bg-destructive/5 px-4 py-3 text-sm text-destructive">
              <AlertTriangle
                className="mt-0.5 size-4 shrink-0"
                aria-hidden="true"
              />
              <p>
                {error.message || "Something went wrong. Please try again."}
              </p>
            </div>
          </div>
        )}
      </div>
      <WorkspaceComposer
        mode="chat"
        active={active}
        input={input}
        onInputChange={setInput}
        onSubmit={handleSubmit}
        busy={isBusy}
        onStop={stop}
        inputRef={inputRef}
      />
    </div>
  );
}