"use client";

import { useEffect, useRef } from "react";
import {
  AssistantRuntimeProvider,
  useLocalRuntime,
  type ChatModelAdapter,
} from "@assistant-ui/react";
import { Thread } from "@/components/assistant-ui/thread";
import { Button } from "@/components/ui/button";
import { RotateCcw } from "lucide-react";

// ---------------------------------------------------------------------------
// Props
// ---------------------------------------------------------------------------

interface AtlasChatProps {
  projectId: string;
  projectName?: string;
}

// ---------------------------------------------------------------------------
// Runtime adapter — calls our existing /api/projects/[id]/atlas-chat endpoint
// ---------------------------------------------------------------------------

function makeAtlasAdapter(projectId: string): ChatModelAdapter {
  return {
    async run({ messages, abortSignal }) {
      const lastUser = [...messages].reverse().find((m) => m.role === "user");
      const text =
        lastUser?.content
          .filter((p) => p.type === "text")
          .map((p) => (p as { type: "text"; text: string }).text)
          .join("") ?? "";

      const res = await fetch(`/api/projects/${projectId}/atlas-chat`, {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ message: text }),
        signal: abortSignal,
      });

      if (!res.ok) {
        const err = await res.json().catch(() => ({}));
        throw new Error(err.error || "Atlas is unavailable. Please try again.");
      }

      const data = await res.json();

      return {
        content: [{ type: "text", text: data.reply || "…" }],
      };
    },
  };
}

// ---------------------------------------------------------------------------
// Inner component — has access to runtime context
// ---------------------------------------------------------------------------

function AtlasChatInner({
  projectId,
  projectName,
  runtime,
}: AtlasChatProps & { runtime: ReturnType<typeof useLocalRuntime> }) {
  const greeted = useRef(false);

  // Send Atlas's opening message automatically on first load
  useEffect(() => {
    if (greeted.current) return;
    greeted.current = true;

    const opener =
      `Hey — I'm starting a new project called "${projectName || "my project"}". I'd love your help defining what we're building.`;

    // Small delay so the thread is mounted before we submit
    const t = setTimeout(() => {
      runtime.thread.composer.setText(opener);
      runtime.thread.composer.send();
    }, 300);

    return () => clearTimeout(t);
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  const handleReset = async () => {
    if (!confirm("Start the discovery conversation over from scratch?")) return;
    await fetch(`/api/projects/${projectId}/atlas-chat`, { method: "DELETE" });
    // Reload to get a fresh runtime state
    window.location.reload();
  };

  return (
    <div className="flex flex-col rounded-2xl overflow-hidden bg-card ring-1 ring-border" style={{ height: "600px" }}>
      {/* Minimal header bar */}
      <div className="flex items-center justify-end px-4 py-2.5 shrink-0 border-b border-border">
        <Button
          variant="ghost"
          size="sm"
          onClick={handleReset}
          className="h-7 w-7 p-0 text-muted-foreground hover:text-foreground"
          title="Start over"
        >
          <RotateCcw className="w-3.5 h-3.5" />
        </Button>
      </div>

      {/* Thread */}
      <div className="flex-1 overflow-hidden">
        <Thread />
      </div>
    </div>
  );
}

// ---------------------------------------------------------------------------
// Main export — wraps with runtime provider
// ---------------------------------------------------------------------------

export function AtlasChat({ projectId, projectName }: AtlasChatProps) {
  const adapter = makeAtlasAdapter(projectId);
  const runtime = useLocalRuntime(adapter);

  return (
    <AssistantRuntimeProvider runtime={runtime}>
      <AtlasChatInner
        projectId={projectId}
        projectName={projectName}
        runtime={runtime}
      />
    </AssistantRuntimeProvider>
  );
}