//! agent_switch_demo —— Agent 角色热切换示例。
//! Required features: cargo run --example agent_switch_demo --features "engine"
//!
//! 演示：
//! 1. 创建 session（绑定 Analyst agent）
//! 2. 提交一轮对话（角色 A 输出"分析数据"）
//! 3. switch_agent 切换为 Reporter agent
//! 4. 提交第二轮对话（角色 B 基于已有上下文输出"报告"）
//! 5. 验证：turn_index 连续、session_memory 保留、slot 历史保留
//!
//! 运行：`cargo run --example agent_switch_demo`

use std::sync::Arc;

use agcore::agent::{Agent, AgentBuilder};
use agcore::engine::SessionManager;
use agcore::llm::hooks::HookExecutor;
use agcore::llm::mock::MockProvider;
use agcore::llm::types::Usage;
use agcore::llm::types::message::{ContentBlock, Message};
use agcore::llm::types::response_v2::{MessageResponse, StopReason};
use agcore::memory::store::InMemoryStore;
use agcore::tools::ToolRegistry;

struct AnalystAgent;
struct ReporterAgent;

impl Agent for AnalystAgent {
    fn name(&self) -> &str {
        "analyst"
    }
    fn system_prompt(&self) -> Option<&str> {
        Some("You are a data analyst. Analyze the input concisely.")
    }
}

impl Agent for ReporterAgent {
    fn name(&self) -> &str {
        "reporter"
    }
    fn system_prompt(&self) -> Option<&str> {
        Some("You are a report writer. Write concise reports based on context.")
    }
}

fn assistant_text(text: &str) -> MessageResponse {
    MessageResponse {
        id: String::new(),
        model: String::new(),
        message: Message::Assistant {
            content: vec![ContentBlock::Text { text: text.into() }],
        },
        usage: Usage::from_input_output(8, 4),
        stop_reason: StopReason::Stop,
        extra: Default::default(),
    }
}

#[tokio::main]
async fn main() {
    println!("=== Agent Switch Demo ===\n");

    // 1. 准备组件
    let store: Arc<dyn agcore::memory::store::MemoryStore> = Arc::new(InMemoryStore::new());
    let provider = Arc::new(MockProvider::new(vec![
        assistant_text("Analyst: data analyzed (Q3 sales up 15%)"),
        assistant_text("Reporter: report drafted (3 paragraphs)"),
    ]));
    let bundle = Arc::new(
        AgentBuilder::new()
            .provider(provider)
            .tool_registry(Arc::new(ToolRegistry::new()))
            .hook_executor(Arc::new(HookExecutor::new()))
            .session_memory_backend(store.clone())
            .build()
            .expect("RuntimeBundle 装配失败"),
    );

    let analyst: Arc<dyn Agent> = Arc::new(AnalystAgent);
    let reporter: Arc<dyn Agent> = Arc::new(ReporterAgent);

    let sm = Arc::new(SessionManager::new(store));
    let session_id = sm.create(analyst, bundle.clone()).await.expect("create");
    println!("[1] session created: {session_id}");

    // 2. Analyst 跑一轮
    let resp1 = sm
        .submit_turn(&session_id, "Analyze Q3 sales data")
        .await
        .expect("submit_turn 1");
    println!("[2] analyst turn 1: {:?}", resp1.text());

    // 3. 切换到 Reporter
    sm.switch_agent(&session_id, reporter)
        .await
        .expect("switch_agent");
    println!("[3] agent switched to 'reporter'");

    // 4. Reporter 跑一轮（基于已有上下文）
    let resp2 = sm
        .submit_turn(&session_id, "Write a report based on the analysis")
        .await
        .expect("submit_turn 2");
    println!("[4] reporter turn 2: {:?}", resp2.text());

    // 5. 验证 turn_index 连续
    let (turn_index, agent_name_owned) = {
        let session = sm.get(&session_id).await.unwrap();
        let guard = session.lock().await;
        (guard.turn_index(), guard.agent.name().to_string())
    };
    println!("\n[verify] turn_index = {turn_index}, agent = {agent_name_owned}");
    assert_eq!(turn_index, 2, "turn_index should be 2 after 2 turns");
    assert_eq!(
        agent_name_owned, "reporter",
        "current agent should be reporter"
    );
    println!("✓ context preserved across agent switch");
}