vylth-flow 0.2.0

use reqwest::{Client, Response, StatusCode};
use serde::Serialize;
use std::collections::HashMap;
use std::time::Duration;

use crate::error::{ErrorBody, FlowError, FlowResult};

const MAX_RETRIES: u32 = 3;
const VERSION: &str = "0.1.0";

pub(crate) struct HttpClient {
    base_url: String,
    api_key: String,
    client: Client,
}

impl HttpClient {
    pub fn new(api_key: &str, base_url: &str, timeout: Duration) -> Self {
        Self {
            base_url: base_url.to_string(),
            api_key: api_key.to_string(),
            client: Client::builder()
                .timeout(timeout)
                .build()
                .expect("failed to build HTTP client"),
        }
    }

    pub async fn get(
        &self,
        path: &str,
        params: Option<&HashMap<String, String>>,
    ) -> FlowResult<Vec<u8>> {
        let url = format!("{}{}", self.base_url, path);
        let mut last_err = None;

        for attempt in 0..MAX_RETRIES {
            let mut req = self
                .client
                .get(&url)
                .header("X-API-Key", &self.api_key)
                .header("User-Agent", format!("flow-rust/{}", VERSION));

            if let Some(p) = params {
                for (k, v) in p {
                    if !v.is_empty() {
                        req = req.query(&[(k.as_str(), v.as_str())]);
                    }
                }
            }

            match req.send().await {
                Ok(resp) => {
                    return self.handle_response(resp, attempt).await;
                }
                Err(e) => {
                    last_err = Some(e);
                    if attempt < MAX_RETRIES - 1 {
                        tokio::time::sleep(backoff(attempt)).await;
                    }
                }
            }
        }

        Err(FlowError::Network(last_err.unwrap()))
    }

    pub async fn post<T: Serialize>(
        &self,
        path: &str,
        body: Option<&T>,
    ) -> FlowResult<Vec<u8>> {
        let url = format!("{}{}", self.base_url, path);
        let mut last_err = None;

        for attempt in 0..MAX_RETRIES {
            let mut req = self
                .client
                .post(&url)
                .header("X-API-Key", &self.api_key)
                .header("Content-Type", "application/json")
                .header("User-Agent", format!("flow-rust/{}", VERSION));

            if let Some(b) = body {
                req = req.json(b);
            }

            match req.send().await {
                Ok(resp) => {
                    return self.handle_response(resp, attempt).await;
                }
                Err(e) => {
                    last_err = Some(e);
                    if attempt < MAX_RETRIES - 1 {
                        tokio::time::sleep(backoff(attempt)).await;
                    }
                }
            }
        }

        Err(FlowError::Network(last_err.unwrap()))
    }

    pub async fn patch<T: Serialize>(
        &self,
        path: &str,
        body: Option<&T>,
    ) -> FlowResult<Vec<u8>> {
        let url = format!("{}{}", self.base_url, path);
        let mut req = self
            .client
            .patch(&url)
            .header("X-API-Key", &self.api_key)
            .header("Content-Type", "application/json")
            .header("User-Agent", format!("flow-rust/{}", VERSION));
        if let Some(b) = body {
            req = req.json(b);
        }
        match req.send().await {
            Ok(resp) => self.handle_response(resp, 0).await,
            Err(e) => Err(FlowError::Network(e)),
        }
    }

    pub async fn delete(&self, path: &str) -> FlowResult<Vec<u8>> {
        let url = format!("{}{}", self.base_url, path);
        let req = self
            .client
            .delete(&url)
            .header("X-API-Key", &self.api_key)
            .header("User-Agent", format!("flow-rust/{}", VERSION));
        match req.send().await {
            Ok(resp) => self.handle_response(resp, 0).await,
            Err(e) => Err(FlowError::Network(e)),
        }
    }

    async fn handle_response(
        &self,
        resp: Response,
        attempt: u32,
    ) -> FlowResult<Vec<u8>> {
        let status = resp.status();
        let retry_after = resp
            .headers()
            .get("Retry-After")
            .and_then(|v| v.to_str().ok())
            .and_then(|v| v.parse::<f64>().ok())
            .unwrap_or(0.0);

        if should_retry(status) && attempt < MAX_RETRIES - 1 {
            let wait = if status == StatusCode::TOO_MANY_REQUESTS && retry_after > 0.0 {
                Duration::from_secs_f64(retry_after)
            } else {
                backoff(attempt)
            };
            tokio::time::sleep(wait).await;
            return Err(FlowError::Other("retry".into()));
        }

        if status == StatusCode::NO_CONTENT {
            return Ok(Vec::new());
        }

        let body = resp.bytes().await.map_err(FlowError::Network)?;

        if status.is_client_error() || status.is_server_error() {
            return Err(parse_error(status.as_u16(), &body, retry_after));
        }

        Ok(body.to_vec())
    }
}

fn backoff(attempt: u32) -> Duration {
    Duration::from_millis(500 * (1 << attempt))
}

fn should_retry(status: StatusCode) -> bool {
    matches!(
        status,
        StatusCode::TOO_MANY_REQUESTS
            | StatusCode::INTERNAL_SERVER_ERROR
            | StatusCode::BAD_GATEWAY
            | StatusCode::SERVICE_UNAVAILABLE
            | StatusCode::GATEWAY_TIMEOUT
    )
}

fn parse_error(status: u16, body: &[u8], retry_after: f64) -> FlowError {
    let err_body: ErrorBody = serde_json::from_slice(body).unwrap_or_default();
    let msg = err_body.msg();
    let code = err_body.code.unwrap_or_default();

    match status {
        401 => FlowError::Authentication {
            message: msg,
            code,
        },
        404 => FlowError::NotFound {
            message: msg,
            code,
        },
        422 => FlowError::Validation {
            message: msg,
            code,
            errors: err_body.errors,
        },
        429 => FlowError::RateLimit {
            message: msg,
            code,
            retry_after,
        },
        500..=599 => FlowError::Server {
            message: msg,
            code,
        },
        _ => FlowError::Api {
            message: msg,
            code,
            status,
        },
    }
}