unistore-http 0.1.0

//! HTTP 客户端实现
//!
//! 职责：
//! - 封装 reqwest 客户端
//! - 提供自动重试机制
//! - 管理连接池和配置

use super::config::{HttpClientConfig, HttpClientConfigBuilder};
use super::error::HttpError;
use super::request::{CancellableRequest, Method, RequestBody, RequestBuilder};
use super::response::Response;

/// HTTP 客户端
///
/// 封装 reqwest，提供：
/// - 合理的默认配置
/// - 自动重试
/// - 与取消系统集成
///
/// # 使用层级
///
/// 1. **Level 3 - 便捷函数**：`get()`, `post_json()`
/// 2. **Level 2 - 客户端实例**：`HttpClient::new()`, `HttpClient::builder()`
/// 3. **Level 1 - 底层访问**：`client.inner()` 获取 reqwest::Client
///
/// # Example
///
/// ```ignore
/// // 默认配置
/// let client = HttpClient::new()?;
/// let resp = client.get("https://api.example.com/data").await?;
///
/// // 自定义配置
/// let client = HttpClient::builder()
///     .timeout(Duration::from_secs(60))
///     .max_retries(5)
///     .build_client()?;
/// ```
#[derive(Debug, Clone)]
pub struct HttpClient {
    inner: reqwest::Client,
    config: HttpClientConfig,
}

impl HttpClient {
    /// 使用默认配置创建客户端
    pub fn new() -> Result<Self, HttpError> {
        Self::with_config(HttpClientConfig::default())
    }

    /// 使用自定义配置创建客户端
    pub fn with_config(config: HttpClientConfig) -> Result<Self, HttpError> {
        let mut builder = reqwest::Client::builder()
            .connect_timeout(config.connect_timeout)
            .timeout(config.request_timeout)
            .user_agent(&config.user_agent)
            .redirect(if config.follow_redirects {
                reqwest::redirect::Policy::limited(config.max_redirects as usize)
            } else {
                reqwest::redirect::Policy::none()
            });

        if config.accept_invalid_certs {
            builder = builder.danger_accept_invalid_certs(true);
        }

        if let Some(proxy) = &config.proxy {
            if let Some(http) = &proxy.http {
                builder = builder.proxy(
                    reqwest::Proxy::http(http)
                        .map_err(|e| HttpError::ClientBuild(format!("HTTP 代理配置错误: {}", e)))?
                );
            }
            if let Some(https) = &proxy.https {
                builder = builder.proxy(
                    reqwest::Proxy::https(https)
                        .map_err(|e| HttpError::ClientBuild(format!("HTTPS 代理配置错误: {}", e)))?
                );
            }
        }

        let inner = builder
            .build()
            .map_err(|e| HttpError::ClientBuild(e.to_string()))?;

        Ok(Self { inner, config })
    }

    /// 创建配置构建器
    pub fn builder() -> HttpClientConfigBuilder {
        HttpClientConfigBuilder::new()
    }

    /// 获取当前配置
    pub fn config(&self) -> &HttpClientConfig {
        &self.config
    }

    /// 访问底层 reqwest::Client（完全控制）
    ///
    /// 当封装无法满足需求时，可以直接使用 reqwest 的所有高级功能
    pub fn inner(&self) -> &reqwest::Client {
        &self.inner
    }

    // ========================================================================
    // 便捷请求方法
    // ========================================================================

    /// GET 请求
    pub async fn get(&self, url: &str) -> Result<Response, HttpError> {
        self.execute(RequestBuilder::new(Method::GET, url)).await
    }

    /// POST 请求（JSON body）
    pub async fn post_json<T: serde::Serialize>(
        &self,
        url: &str,
        body: &T,
    ) -> Result<Response, HttpError> {
        let builder = RequestBuilder::new(Method::POST, url).json(body)?;
        self.execute(builder).await
    }

    /// POST 请求（表单 body）
    pub async fn post_form<T: serde::Serialize>(
        &self,
        url: &str,
        body: &T,
    ) -> Result<Response, HttpError> {
        let builder = RequestBuilder::new(Method::POST, url).form(body)?;
        self.execute(builder).await
    }

    /// PUT 请求（JSON body）
    pub async fn put_json<T: serde::Serialize>(
        &self,
        url: &str,
        body: &T,
    ) -> Result<Response, HttpError> {
        let builder = RequestBuilder::new(Method::PUT, url).json(body)?;
        self.execute(builder).await
    }

    /// DELETE 请求
    pub async fn delete(&self, url: &str) -> Result<Response, HttpError> {
        self.execute(RequestBuilder::new(Method::DELETE, url)).await
    }

    /// PATCH 请求（JSON body）
    pub async fn patch_json<T: serde::Serialize>(
        &self,
        url: &str,
        body: &T,
    ) -> Result<Response, HttpError> {
        let builder = RequestBuilder::new(Method::PATCH, url).json(body)?;
        self.execute(builder).await
    }

    /// HEAD 请求
    pub async fn head(&self, url: &str) -> Result<Response, HttpError> {
        self.execute(RequestBuilder::new(Method::HEAD, url)).await
    }

    // ========================================================================
    // 构建请求
    // ========================================================================

    /// 创建请求构建器
    pub fn request(&self, method: Method, url: &str) -> RequestBuilder {
        RequestBuilder::new(method, url)
    }

    /// 执行请求（带自动重试）
    pub async fn execute(&self, builder: RequestBuilder) -> Result<Response, HttpError> {
        self.execute_with_retry(builder).await
    }

    /// 执行可取消的请求
    pub async fn execute_cancellable(
        &self,
        request: CancellableRequest,
    ) -> Result<Response, HttpError> {
        tokio::select! {
            result = self.execute_with_retry(request.builder) => result,
            _ = request.cancel_token.cancelled() => Err(HttpError::Cancelled),
        }
    }

    // ========================================================================
    // 内部实现
    // ========================================================================

    async fn execute_with_retry(&self, builder: RequestBuilder) -> Result<Response, HttpError> {
        let max_retries = builder.max_retries.unwrap_or(self.config.max_retries);
        let retry_strategy = builder
            .retry_strategy
            .clone()
            .unwrap_or_else(|| self.config.retry_strategy.clone());

        let mut attempts = 0;

        loop {
            attempts += 1;

            match self.execute_once(&builder).await {
                Ok(resp) => {
                    // 5xx 错误也重试
                    if resp.is_server_error() && attempts <= max_retries {
                        // 继续重试循环
                    } else {
                        return Ok(resp);
                    }
                }
                Err(e) if e.is_retryable() && attempts <= max_retries => {
                    // 继续重试循环
                }
                Err(e) => return Err(e),
            }

            // 计算重试延迟
            if let Some(delay) = retry_strategy.delay_for_attempt(attempts) {
                tokio::time::sleep(delay).await;
            } else {
                // 已超过最大重试次数
                return Err(HttpError::RequestTimeout);
            }
        }
    }

    async fn execute_once(&self, builder: &RequestBuilder) -> Result<Response, HttpError> {
        let url = builder.build_url()?;

        let method = match builder.method {
            Method::GET => reqwest::Method::GET,
            Method::POST => reqwest::Method::POST,
            Method::PUT => reqwest::Method::PUT,
            Method::DELETE => reqwest::Method::DELETE,
            Method::PATCH => reqwest::Method::PATCH,
            Method::HEAD => reqwest::Method::HEAD,
            Method::OPTIONS => reqwest::Method::OPTIONS,
        };

        let mut req = self.inner.request(method, &url);

        // 添加请求头
        for (key, value) in &builder.headers {
            req = req.header(key.as_str(), value.as_str());
        }

        // 设置超时
        if let Some(timeout) = builder.timeout {
            req = req.timeout(timeout);
        }

        // 设置请求体
        match &builder.body {
            RequestBody::None => {}
            RequestBody::Json(bytes) => {
                req = req.body(bytes.clone());
            }
            RequestBody::Form(encoded) => {
                req = req.body(encoded.clone());
            }
            RequestBody::Bytes(bytes) => {
                req = req.body(bytes.clone());
            }
            RequestBody::Text(text) => {
                req = req.body(text.clone());
            }
        }

        let resp = req.send().await?;
        Response::from_reqwest(resp).await
    }
}

impl Default for HttpClient {
    fn default() -> Self {
        Self::new().expect("创建默认 HTTP 客户端失败")
    }
}

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

    #[test]
    fn test_client_config() {
        let config = HttpClientConfig::default();
        assert_eq!(config.connect_timeout, Duration::from_secs(10));
        assert_eq!(config.max_retries, 3);
    }

    #[test]
    fn test_builder_methods() {
        let builder = HttpClient::builder()
            .timeout(Duration::from_secs(60))
            .max_retries(5)
            .no_retry()
            .build();

        assert_eq!(builder.request_timeout, Duration::from_secs(60));
        assert_eq!(builder.max_retries, 0);
    }
}