//! ## 和风天气查询工具（Rust 原生实现）
//!
//! 通过和风天气 API 查询实时天气、每日预报和逐小时预报。
//!
//! ### API 端点
//! - 城市查询: `GET /geo/v2/city/lookup?location=城市名` → 获取 city_id
//! - 实时天气: `GET /v7/weather/now?location=city_id`
//! - 每日预报: `GET /v7/weather/{3,7,10,15,30}d?location=id`
//! - 逐时预报: `GET /v7/weather/{24,72,168}h?location=id`
//!
//! ### 认证方式
//! 使用 EdDSA (Ed25519) JWT 进行 API 认证。
//! 密钥对存放在 `qweather/` 目录下。
//!
//! ### 环境变量
//! - `QWEATHER_API_HOST` — API 地址（默认 `api.qweather.com`）
//! - `QWEATHER_JWT_KEY_ID` — JWT Key ID
//! - `QWEATHER_JWT_PROJECT_ID` — 项目 ID
//! - `QWEATHER_JWT_PRIVATE_KEY_FILE` — Ed25519 私钥路径
//!
//! ### 缓存策略
//! city_id 在内存中缓存 1 小时（TTL），减少重复查询。

use base64::{Engine as _, engine::general_purpose};
use chrono::Utc;
use ed25519_dalek::pkcs8::DecodePrivateKey;
use ed25519_dalek::{Signer, SigningKey};
use reqwest::Client;
use serde::Deserialize;
use std::collections::HashMap;
use std::sync::Mutex;
use std::time::{Duration, Instant};

use crate::tools::types::{RiskLevel, SkillResult, SkillSpec};

// ═══════════════════════════════════════════════
// JWT 认证
// ═══════════════════════════════════════════════

fn base64url(data: &[u8]) -> String {
    general_purpose::URL_SAFE_NO_PAD.encode(data)
}

fn generate_jwt() -> Result<String, String> {
    let key_file = std::env::var("QWEATHER_JWT_PRIVATE_KEY_FILE").unwrap_or_else(|_| {
        dirs::home_dir()
            .unwrap_or_else(|| std::path::PathBuf::from("."))
            .join(".ias")
            .join("qweather")
            .join("ed25519-private.pem")
            .to_string_lossy()
            .to_string()
    });

    let pem = std::fs::read_to_string(&key_file)
        .map_err(|e| format!("读取密钥文件 {} 失败: {}", key_file, e))?;

    let signing_key = SigningKey::from_pkcs8_pem(&pem)
        .map_err(|e| format!("解析 Ed25519 密钥失败: {e}"))?;

    let key_id = std::env::var("QWEATHER_JWT_KEY_ID").unwrap_or_default();
    let project_id = std::env::var("QWEATHER_JWT_PROJECT_ID").unwrap_or_default();
    let ttl: i64 = std::env::var("QWEATHER_JWT_TTL_SECONDS")
        .ok()
        .and_then(|s| s.parse().ok())
        .unwrap_or(3600);

    let now = Utc::now().timestamp();

    // Header
    let header = serde_json::json!({"alg": "EdDSA", "kid": key_id});
    let header_b64 = base64url(header.to_string().as_bytes());

    // Payload
    let payload = serde_json::json!({
        "sub": project_id,
        "iat": now - 30,
        "exp": now + ttl,
    });
    let payload_b64 = base64url(payload.to_string().as_bytes());

    // Sign
    let message = format!("{}.{}", header_b64, payload_b64);
    let signature = signing_key
        .try_sign(message.as_bytes())
        .map_err(|e| format!("JWT 签名失败: {e}"))?;

    Ok(format!(
        "{}.{}.{}",
        header_b64,
        payload_b64,
        base64url(&signature.to_bytes())
    ))
}

// ═══════════════════════════════════════════════
// API 响应类型
// ═══════════════════════════════════════════════

#[derive(Deserialize)]
struct CityLookupResponse {
    code: String,
    #[serde(default)]
    location: Vec<CityLocation>,
}

#[derive(Deserialize)]
#[allow(dead_code)]
struct CityLocation {
    id: String,
    name: String,
    #[serde(default)]
    adm1: String,
    #[serde(default)]
    adm2: String,
}

#[derive(Deserialize)]
struct WeatherNowResponse {
    code: String,
    #[serde(default)]
    now: Option<WeatherNow>,
}

#[derive(Deserialize)]
struct WeatherNow {
    #[serde(default)]
    temp: String,
    #[serde(rename = "feelsLike", default)]
    feels_like: String,
    #[serde(default)]
    text: String,
    #[serde(rename = "windDir", default)]
    wind_dir: String,
    #[serde(rename = "windScale", default)]
    wind_scale: String,
    #[serde(rename = "windSpeed", default)]
    wind_speed: String,
    #[serde(default)]
    humidity: String,
    #[serde(default)]
    precip: String,
    #[serde(default)]
    pressure: String,
    #[serde(default)]
    vis: String,
}

#[derive(Deserialize)]
struct DailyForecastResponse {
    code: String,
    #[serde(default)]
    daily: Vec<DailyForecast>,
}

#[derive(Deserialize)]
struct DailyForecast {
    #[serde(rename = "fxDate", default)]
    fx_date: String,
    #[serde(rename = "tempMax", default)]
    temp_max: String,
    #[serde(rename = "tempMin", default)]
    temp_min: String,
    #[serde(rename = "textDay", default)]
    text_day: String,
    #[serde(rename = "textNight", default)]
    text_night: String,
    #[serde(rename = "windDirDay", default)]
    wind_dir_day: String,
    #[serde(rename = "windScaleDay", default)]
    wind_scale_day: String,
    #[serde(default)]
    humidity: String,
    #[serde(rename = "uvIndex", default)]
    uv_index: String,
}

#[derive(Deserialize)]
struct HourlyForecastResponse {
    code: String,
    #[serde(default)]
    hourly: Vec<HourlyForecast>,
}

#[derive(Deserialize)]
struct HourlyForecast {
    #[serde(rename = "fxTime", default)]
    fx_time: String,
    #[serde(default)]
    temp: String,
    #[serde(default)]
    text: String,
    #[serde(rename = "windDir", default)]
    wind_dir: String,
    #[serde(rename = "windScale", default)]
    wind_scale: String,
    #[serde(default)]
    humidity: String,
    #[serde(default)]
    pop: String,
    #[serde(default)]
    precip: String,
}

// ═══════════════════════════════════════════════
// 城市 ID 缓存
// ═══════════════════════════════════════════════

/// 持久化 city_id 映射，减少 API 调用
use std::sync::LazyLock;
static CITY_CACHE: LazyLock<Mutex<HashMap<String, (String, Instant)>>> =
    LazyLock::new(|| Mutex::new(HashMap::new()));
const CACHE_TTL: Duration = Duration::from_secs(3600);

fn get_cached_city(query: &str) -> Option<String> {
    let cache = CITY_CACHE.lock().unwrap();
    cache.get(query).and_then(|(id, ts)| {
        if ts.elapsed() < CACHE_TTL {
            Some(id.clone())
        } else {
            None
        }
    })
}

fn cache_city(query: String, city_id: String) {
    let mut cache = CITY_CACHE.lock().unwrap();
    cache.insert(query, (city_id, Instant::now()));
}

// ═══════════════════════════════════════════════
// HTTP 客户端
// ═══════════════════════════════════════════════

struct QWeatherClient {
    http: Client,
    jwt: String,
    api_host: String,
}

impl QWeatherClient {
    async fn new() -> Result<Self, String> {
        let jwt = generate_jwt()?;
        let api_host =
            std::env::var("QWEATHER_API_HOST").unwrap_or_else(|_| "api.qweather.com".into());

        Ok(Self {
            http: Client::builder()
                .timeout(Duration::from_secs(10))
                .build()
                .map_err(|e| format!("创建 HTTP client 失败: {}", e))?,
            jwt,
            api_host,
        })
    }

    /// 城市查询 → LocationID
    async fn lookup_city(&self, location: &str) -> Result<String, String> {
        // 检查缓存
        if let Some(id) = get_cached_city(location) {
            tracing::debug!("🏙️  城市缓存命中: {} → {}", location, id);
            return Ok(id);
        }

        let resp: CityLookupResponse = self
            .http
            .get("https://geoapi.qweather.com/v2/city/lookup")
            .query(&[("location", location), ("number", "1")])
            .header("Authorization", format!("Bearer {}", self.jwt))
            .send()
            .await
            .map_err(|e| format!("城市查询请求失败: {}", e))?
            .json()
            .await
            .map_err(|e| format!("解析城市查询响应失败: {}", e))?;

        if resp.code != "200" {
            return Err(format!("城市查询 API 返回: {}", resp.code));
        }

        let city = resp
            .location
            .first()
            .ok_or_else(|| format!("未找到城市: {}", location))?;

        let id = city.id.clone();
        cache_city(location.to_string(), id.clone());
        tracing::debug!("🏙️  城市查询: {} → {} ({})", location, city.name, id);

        Ok(id)
    }

    /// 实时天气
    async fn weather_now(&self, city_id: &str) -> Result<serde_json::Value, String> {
        let resp: WeatherNowResponse = self
            .http
            .get(format!("https://{}/v7/weather/now", self.api_host))
            .query(&[("location", city_id), ("lang", "zh"), ("unit", "m")])
            .header("Authorization", format!("Bearer {}", self.jwt))
            .send()
            .await
            .map_err(|e| format!("实时天气请求失败: {}", e))?
            .json()
            .await
            .map_err(|e| format!("解析实时天气响应失败: {}", e))?;

        if resp.code != "200" {
            return Err(format!("实时天气 API 返回: {}", resp.code));
        }

        let now = resp.now.ok_or("实时天气数据为空")?;

        Ok(serde_json::json!({
            "temp": now.temp,
            "feelsLike": now.feels_like,
            "text": now.text,
            "windDir": now.wind_dir,
            "windScale": now.wind_scale,
            "windSpeed": now.wind_speed,
            "humidity": now.humidity,
            "precip": now.precip,
            "pressure": now.pressure,
            "vis": now.vis,
        }))
    }

    /// 每日预报
    async fn daily_forecast(&self, city_id: &str, days: u32) -> Result<serde_json::Value, String> {
        let d = match days {
            0..=3 => "3d",
            4..=7 => "7d",
            8..=10 => "10d",
            11..=15 => "15d",
            _ => "30d",
        };

        let resp: DailyForecastResponse = self
            .http
            .get(format!("https://{}/v7/weather/{}", self.api_host, d))
            .query(&[("location", city_id), ("lang", "zh"), ("unit", "m")])
            .header("Authorization", format!("Bearer {}", self.jwt))
            .send()
            .await
            .map_err(|e| format!("每日预报请求失败: {}", e))?
            .json()
            .await
            .map_err(|e| format!("解析每日预报响应失败: {}", e))?;

        if resp.code != "200" {
            return Err(format!("每日预报 API 返回: {}", resp.code));
        }

        let forecast: Vec<serde_json::Value> = resp
            .daily
            .into_iter()
            .take(days as usize)
            .map(|d| {
                serde_json::json!({
                    "date": d.fx_date,
                    "tempMax": d.temp_max,
                    "tempMin": d.temp_min,
                    "textDay": d.text_day,
                    "textNight": d.text_night,
                    "windDirDay": d.wind_dir_day,
                    "windScaleDay": d.wind_scale_day,
                    "humidity": d.humidity,
                    "uvIndex": d.uv_index,
                })
            })
            .collect();

        Ok(serde_json::Value::Array(forecast))
    }

    /// 逐时预报
    async fn hourly_forecast(
        &self,
        city_id: &str,
        hours: u32,
    ) -> Result<serde_json::Value, String> {
        let h = match hours {
            0..=24 => "24h",
            25..=72 => "72h",
            _ => "168h",
        };

        let resp: HourlyForecastResponse = self
            .http
            .get(format!("https://{}/v7/weather/{}", self.api_host, h))
            .query(&[("location", city_id), ("lang", "zh"), ("unit", "m")])
            .header("Authorization", format!("Bearer {}", self.jwt))
            .send()
            .await
            .map_err(|e| format!("逐时预报请求失败: {}", e))?
            .json()
            .await
            .map_err(|e| format!("解析逐时预报响应失败: {}", e))?;

        if resp.code != "200" {
            return Err(format!("逐时预报 API 返回: {}", resp.code));
        }

        let forecast: Vec<serde_json::Value> = resp
            .hourly
            .into_iter()
            .take(hours as usize)
            .map(|h| {
                serde_json::json!({
                    "time": h.fx_time,
                    "temp": h.temp,
                    "text": h.text,
                    "windDir": h.wind_dir,
                    "windScale": h.wind_scale,
                    "humidity": h.humidity,
                    "pop": h.pop,
                    "precip": h.precip,
                })
            })
            .collect();

        Ok(serde_json::Value::Array(forecast))
    }
}

// ═══════════════════════════════════════════════
// 公开接口 — 3 个独立工具
// ═══════════════════════════════════════════════

/// 1. weather_now — 实时天气
pub fn now_spec() -> SkillSpec {
    SkillSpec {
        name: "weather_now".into(),
        description: "查询指定城市的实时天气（温度、体感温度、天气状况、风向风力、湿度、降水量、气压、能见度）。参数 location 为城市名".into(),
        risk_level: RiskLevel::Low,
        parameters: serde_json::json!({
            "type": "object",
            "properties": {
                "location": {"type": "string", "description": "城市名，如 北京、上海"}
            },
            "required": ["location"]
        }),
        timeout_secs: 10,
    }
}

pub async fn now_execute(params: serde_json::Value) -> SkillResult {
    let location = params
        .get("location")
        .and_then(|v| v.as_str())
        .unwrap_or("");
    if location.is_empty() {
        return SkillResult::error("请提供 location（城市名）");
    }

    let client = match QWeatherClient::new().await {
        Ok(c) => c,
        Err(e) => return SkillResult::error(format!("初始化天气客户端失败: {}", e)),
    };
    let city_id = match client.lookup_city(location).await {
        Ok(id) => id,
        Err(e) => return SkillResult::error(e),
    };

    match client.weather_now(&city_id).await {
        Ok(data) => {
            let output = serde_json::json!({"location": location, "now": data});
            SkillResult::ok_with_data(serde_json::to_string(&output).unwrap_or_default(), output)
        }
        Err(e) => SkillResult::error(e),
    }
}

/// 2. weather_forecast — 每日预报
pub fn forecast_spec() -> SkillSpec {
    SkillSpec {
        name: "weather_forecast".into(),
        description: "查询指定城市未来几天的天气预报（最高/最低温度、白天/夜间天气状况、风向风力、湿度、紫外线指数）。参数 location 为城市名，days 为预报天数（默认3，最大30）".into(),
        risk_level: RiskLevel::Low,
        parameters: serde_json::json!({
            "type": "object",
            "properties": {
                "location": {"type": "string", "description": "城市名，如 北京、上海"},
                "days": {"type": "integer", "description": "预报天数，默认3，最大30"}
            },
            "required": ["location"]
        }),
        timeout_secs: 10,
    }
}

pub async fn forecast_execute(params: serde_json::Value) -> SkillResult {
    let location = params
        .get("location")
        .and_then(|v| v.as_str())
        .unwrap_or("");
    if location.is_empty() {
        return SkillResult::error("请提供 location（城市名）");
    }
    let days = params
        .get("days")
        .and_then(|v| v.as_u64())
        .unwrap_or(3)
        .min(30)
        .max(1) as u32;

    let client = match QWeatherClient::new().await {
        Ok(c) => c,
        Err(e) => return SkillResult::error(format!("初始化天气客户端失败: {}", e)),
    };
    let city_id = match client.lookup_city(location).await {
        Ok(id) => id,
        Err(e) => return SkillResult::error(e),
    };

    match client.daily_forecast(&city_id, days).await {
        Ok(data) => {
            let output = serde_json::json!({"location": location, "forecast": data});
            SkillResult::ok_with_data(serde_json::to_string(&output).unwrap_or_default(), output)
        }
        Err(e) => SkillResult::error(e),
    }
}

/// 3. weather_hourly — 逐时预报
pub fn hourly_spec() -> SkillSpec {
    SkillSpec {
        name: "weather_hourly".into(),
        description: "查询指定城市未来逐小时的天气预报（温度、天气状况、风向风力、湿度、降水概率、降水量）。参数 location 为城市名，hours 为预报小时数（默认24，最大168）".into(),
        risk_level: RiskLevel::Low,
        parameters: serde_json::json!({
            "type": "object",
            "properties": {
                "location": {"type": "string", "description": "城市名，如 北京、上海"},
                "hours": {"type": "integer", "description": "预报小时数，默认24，最大168"}
            },
            "required": ["location"]
        }),
        timeout_secs: 10,
    }
}

pub async fn hourly_execute(params: serde_json::Value) -> SkillResult {
    let location = params
        .get("location")
        .and_then(|v| v.as_str())
        .unwrap_or("");
    if location.is_empty() {
        return SkillResult::error("请提供 location（城市名）");
    }
    let hours = params
        .get("hours")
        .and_then(|v| v.as_u64())
        .unwrap_or(24)
        .min(168)
        .max(1) as u32;

    let client = match QWeatherClient::new().await {
        Ok(c) => c,
        Err(e) => return SkillResult::error(format!("初始化天气客户端失败: {}", e)),
    };
    let city_id = match client.lookup_city(location).await {
        Ok(id) => id,
        Err(e) => return SkillResult::error(e),
    };

    match client.hourly_forecast(&city_id, hours).await {
        Ok(data) => {
            let output = serde_json::json!({"location": location, "hourly": data});
            SkillResult::ok_with_data(serde_json::to_string(&output).unwrap_or_default(), output)
        }
        Err(e) => SkillResult::error(e),
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_jwt_generation() {
        // 仅验证能生成非空 token（需要有效的密钥文件）
        let result = generate_jwt();
        if result.is_ok() {
            let jwt = result.unwrap();
            let parts: Vec<&str> = jwt.split('.').collect();
            assert_eq!(parts.len(), 3, "JWT 应该有 3 部分");
            assert!(!parts[0].is_empty());
            assert!(!parts[1].is_empty());
            assert!(!parts[2].is_empty());
        }
    }

    /// 端到端测试：需要有效的 QWeather 环境变量
    #[tokio::test]
    async fn test_now_execute_integration() {
        if std::env::var("QWEATHER_JWT_KEY_ID").is_err() {
            eprintln!("跳过集成测试: 未设置 QWeather 环境变量");
            return;
        }
        let result = super::now_execute(serde_json::json!({"location": "合肥"})).await;
        assert!(result.success, "查询失败: {}", result.output);
        let data = result.data.expect("应有 data 字段");
        assert_eq!(data["location"], "合肥");
        assert!(data["now"].is_object(), "应有实时天气");
    }

    #[tokio::test]
    async fn test_forecast_execute_integration() {
        if std::env::var("QWEATHER_JWT_KEY_ID").is_err() {
            eprintln!("跳过集成测试: 未设置 QWeather 环境变量");
            return;
        }
        let result =
            super::forecast_execute(serde_json::json!({"location": "合肥", "days": 3})).await;
        assert!(result.success, "查询失败: {}", result.output);
        let data = result.data.expect("应有 data 字段");
        assert_eq!(data["location"], "合肥");
        assert!(data["forecast"].is_array(), "应有预报");
    }
}