import "dotenv/config"
import { createAgent, HumanMessage, SystemMessage, summarizationMiddleware, tool } from "langchain"
import { MemorySaver } from "@langchain/langgraph"
import { ChatGoogleGenerativeAI } from "@langchain/google-genai"
import { z } from "zod"

const model = new ChatGoogleGenerativeAI({
  model: "models/gemini-2.5-flash-preview-09-2025",
  temperature: 0,
  apiKey: process.env.GEMINI_API_KEY,
  baseUrl: "https://generativelanguage.googleapis.com",
})

const searchTool = tool(
  ({ query }: { query: string }) => {
    console.log(`Searching for: ${query}`)
    return `Found results for: ${query}`
  },
  {
    name: "search",
    description: "Search for information",
    schema: z.object({
      query: z.string().describe("The search query"),
    }),
  }
)

const agent = createAgent({
  model,
  tools: [searchTool],
  checkpointer: new MemorySaver(),
  middleware: [
    summarizationMiddleware({
      model: model,
      maxTokensBeforeSummary: 100,
      messagesToKeep: 10,
    })
  ],
})

const threadId = "bug-reproduction"

console.log("\n=== Message 1: Hi (with system message) ===")
await agent.invoke(
  { messages: [new SystemMessage("You are a helpful assistant."), new HumanMessage("Hi")] },
  { configurable: { thread_id: threadId } }
)

console.log("\n=== Message 2: Search for cats ===")
await agent.invoke(
  { messages: [new HumanMessage("Search for cats")] },
  { configurable: { thread_id: threadId } }
)

console.log("\n=== Message 3: Search for dogs ===")
await agent.invoke(
  { messages: [new HumanMessage("Search for dogs")] },
  { configurable: { thread_id: threadId } }
)

console.log("\n=== Message 4: Search for birds (should trigger summarization and fail) ===")
try {
  await agent.invoke(
    { messages: [new HumanMessage("Search for birds")] },
    { configurable: { thread_id: threadId } }
  )
  console.log("✓ Success - no error (bug not reproduced)")
} catch (error: any) {
  if (error.message.includes("function call turn comes immediately after")) {
    console.log("\n✗ BUG REPRODUCED!")
    console.log("Error:", error.message)
  } else {
    console.log("✗ Different error:", error.message)
  }
}