//! task_agent_demo —— Plan 解析、Step 状态机、错误路径。
//! Required features: cargo run --example task_agent_demo --features "agent"
//!
//! 演示：
//! 1. `JsonPlanParser::parse` 解析合法 JSON 输入
//! 2. `Plan` / `Step` 数据结构遍历
//! 3. `StepStatus` 状态机：Pending → Running → Completed / Failed / Skipped
//! 4. `is_pending()` / `is_terminal()` 语义
//! 5. 错误路径：非法 JSON / 空 steps / 缺字段 → `AgentError::PlanParse`
//!
//! 运行：`cargo run --example task_agent_demo`

use std::collections::HashMap;

use agcore::agent::{AgentError, JsonPlanParser, PlanParser, Step, StepStatus};
use agcore::llm::types::Usage;
use agcore::llm::types::message::Message;
use agcore::llm::types::response_v2::{MessageResponse, StopReason};

#[tokio::main]
async fn main() {
    // 1. JsonPlanParser 解析合法 JSON
    println!("=== JsonPlanParser 解析合法 JSON ===");
    let parser = JsonPlanParser;
    let input = r#"{
        "steps": [
            {"description": "查询北京天气"},
            {"description": "根据天气计算穿衣建议"},
            {"description": "生成最终回复"}
        ]
    }"#;
    let plan = parser
        .parse(input, "为用户生成今日出行建议")
        .await
        .expect("合法 JSON 应解析成功");
    println!("Plan goal: {}", plan.goal);
    println!("Plan id:   {}", plan.id);
    println!("Steps:     {}", plan.steps.len());
    for (i, step) in plan.steps.iter().enumerate() {
        println!(
            "  [{}] {} (pending={}, terminal={})",
            i,
            step.description,
            step.status.is_pending(),
            step.status.is_terminal()
        );
    }
    assert!(plan.steps.iter().all(|s| s.status.is_pending()));

    // 2. Step 状态机：Pending → Running → Completed
    println!("\n=== Step 状态机：Pending → Running → Completed ===");
    let mut step = plan.steps.into_iter().next().expect("应有 step");
    println!("初始:   pending={}", step.status.is_pending());
    assert!(step.status.is_pending());

    step.status = StepStatus::Running;
    println!(
        "Running: pending={}, terminal={}",
        step.status.is_pending(),
        step.status.is_terminal()
    );

    step.status = StepStatus::Completed(MessageResponse {
        id: String::new(),
        model: "mock".into(),
        message: Message::assistant("天气：晴，22°C"),
        usage: Usage::from_input_output(5, 10),
        stop_reason: StopReason::Stop,
        extra: HashMap::new(),
    });
    println!(
        "Completed: pending={}, terminal={}",
        step.status.is_pending(),
        step.status.is_terminal()
    );
    assert!(step.status.is_terminal());

    // 3. 失败路径
    println!("\n=== Step 状态机：失败路径 ===");
    let mut fail_step = Step::new(0, "调用天气 API");
    fail_step.status = StepStatus::Failed(AgentError::Other("API 不可用".into()));
    println!(
        "Failed:  pending={}, terminal={}",
        fail_step.status.is_pending(),
        fail_step.status.is_terminal()
    );
    assert!(fail_step.status.is_terminal());

    // 4. 跳过路径
    let mut skipped = Step::new(0, "可选步骤");
    skipped.status = StepStatus::Skipped;
    println!("Skipped: terminal={}", skipped.status.is_terminal());
    assert!(skipped.status.is_terminal());

    // 5. 错误路径 1：非法 JSON
    println!("\n=== 错误路径：非法 JSON ===");
    let err = parser.parse("not json", "goal").await.unwrap_err();
    println!("错误: {err}");
    assert!(matches!(err, AgentError::PlanParse(_)));

    // 6. 错误路径 2：空 steps
    println!("\n=== 错误路径：空 steps ===");
    let err = parser.parse(r#"{"steps": []}"#, "goal").await.unwrap_err();
    println!("错误: {err}");
    assert!(matches!(err, AgentError::PlanParse(_)));

    // 7. 错误路径 3：缺 description 字段
    println!("\n=== 错误路径：缺 description 字段 ===");
    let bad_input = r#"{"steps": [{"description": "ok"}, {"no_desc": true}]}"#;
    let err = parser.parse(bad_input, "goal").await.unwrap_err();
    println!("错误: {err}");
    assert!(matches!(err, AgentError::PlanParse(_)));

    println!("\n✓ task_agent_demo 完成");
}