highlevel-api 0.2.0

use std::sync::atomic::{AtomicU32, Ordering};
use std::sync::Arc;
use std::time::{Duration, SystemTime, UNIX_EPOCH};

use reqwest::{Client, RequestBuilder, Response};
use serde::{de::DeserializeOwned, Serialize};
use tokio::sync::RwLock;
use tokio::time::Instant;

use crate::{
    config::HighLevelConfig,
    error::{Error, Result},
};

const DEFAULT_RATE: u32 = 95;
const DEFAULT_WINDOW_SECS: u64 = 10;
const MAX_RETRIES: u32 = 3;
const CIRCUIT_BREAK_THRESHOLD: u32 = 3;
const CIRCUIT_BREAK_RESET_SECS: u64 = 30;

struct TokenBucket {
    capacity: u32,
    tokens: f64,
    refill_per_sec: f64,
    last_refill: Instant,
}

impl TokenBucket {
    fn new(capacity: u32, window_secs: u64) -> Self {
        Self {
            capacity,
            tokens: capacity as f64,
            refill_per_sec: capacity as f64 / window_secs as f64,
            last_refill: Instant::now(),
        }
    }

    fn try_acquire(&mut self) -> bool {
        self.refill();
        if self.tokens >= 1.0 {
            self.tokens -= 1.0;
            true
        } else {
            false
        }
    }

    fn refill(&mut self) {
        let elapsed = self.last_refill.elapsed().as_secs_f64();
        self.tokens = (self.tokens + elapsed * self.refill_per_sec).min(self.capacity as f64);
        self.last_refill = Instant::now();
    }
}

struct CircuitBreaker {
    consecutive_429s: AtomicU32,
    open_until: RwLock<Option<Instant>>,
}

impl CircuitBreaker {
    fn new() -> Self {
        Self {
            consecutive_429s: AtomicU32::new(0),
            open_until: RwLock::new(None),
        }
    }

    async fn is_open(&self) -> bool {
        if let Some(until) = *self.open_until.read().await {
            if Instant::now() < until {
                return true;
            }
            self.open_until.write().await.take();
            self.consecutive_429s.store(0, Ordering::SeqCst);
        }
        false
    }

    async fn record_429(&self) {
        let count = self.consecutive_429s.fetch_add(1, Ordering::SeqCst) + 1;
        if count >= CIRCUIT_BREAK_THRESHOLD {
            *self.open_until.write().await =
                Some(Instant::now() + Duration::from_secs(CIRCUIT_BREAK_RESET_SECS));
        }
    }

    async fn record_success(&self) {
        self.consecutive_429s.store(0, Ordering::SeqCst);
        self.open_until.write().await.take();
    }
}

pub struct HttpClient {
    inner: Client,
    pub base_url: String,
    pub api_version: String,
    token: RwLock<Option<String>>,
    bucket: RwLock<TokenBucket>,
    breaker: CircuitBreaker,
}

impl HttpClient {
    pub fn new(config: &HighLevelConfig) -> Self {
        Self {
            inner: Client::new(),
            base_url: config.base_url.clone(),
            api_version: config.api_version.clone(),
            token: RwLock::new(None),
            bucket: RwLock::new(TokenBucket::new(DEFAULT_RATE, DEFAULT_WINDOW_SECS)),
            breaker: CircuitBreaker::new(),
        }
    }

    pub async fn set_token(&self, token: String) {
        *self.token.write().await = Some(token);
    }

    pub async fn get_token(&self) -> Option<String> {
        self.token.read().await.clone()
    }

    fn url(&self, path: &str) -> String {
        format!("{}{}", self.base_url, path)
    }

    async fn acquire_token(&self) -> Result<()> {
        if self.breaker.is_open().await {
            return Err(Error::RateLimited {
                retry_after: Some(CIRCUIT_BREAK_RESET_SECS),
                circuit_breaker: true,
            });
        }
        loop {
            if self.bucket.write().await.try_acquire() {
                return Ok(());
            }
            tokio::time::sleep(Duration::from_millis(50)).await;
        }
    }

    /// Execute a request with rate-limit awareness, retry-on-429, and circuit
    /// breaking. `build` is a closure (called once per attempt) that receives a
    /// `&Client` and returns a `RequestBuilder`. Auth is applied automatically.
    async fn execute_with_retry<F>(&self, build: F) -> Result<Response>
    where
        F: Fn(&Client) -> RequestBuilder,
    {
        self.acquire_token().await?;

        let token = self.token.read().await.clone();
        let mut builder = build(&self.inner);
        if let Some(ref t) = token {
            builder = builder.bearer_auth(t);
        }
        let req = builder.build()?;
        let mut response = self.inner.execute(req).await?;

        let mut retries = 0u32;
        while response.status() == 429 && retries < MAX_RETRIES {
            self.breaker.record_429().await;

            let delay = exponential_backoff(retries) + jitter();
            tokio::time::sleep(delay).await;

            let token = self.token.read().await.clone();
            let mut builder = build(&self.inner);
            if let Some(ref t) = token {
                builder = builder.bearer_auth(t);
            }
            let req = builder.build()?;
            response = self.inner.execute(req).await?;
            retries += 1;
        }

        if response.status() == 429 {
            let retry_after = response
                .headers()
                .get("Retry-After")
                .and_then(|v| v.to_str().ok())
                .and_then(|v| v.parse::<u64>().ok());
            return Err(Error::RateLimited {
                retry_after,
                circuit_breaker: self.breaker.is_open().await,
            });
        }

        self.breaker.record_success().await;
        Ok(response)
    }

    async fn handle_response<T: DeserializeOwned>(&self, resp: Response) -> Result<T> {
        let status = resp.status();
        if status.is_success() {
            Ok(resp.json::<T>().await?)
        } else {
            let code = status.as_u16();
            let body = resp.text().await.unwrap_or_default();
            let message = serde_json::from_str::<serde_json::Value>(&body)
                .ok()
                .and_then(|v| {
                    v.get("message")
                        .and_then(|m| m.as_str())
                        .map(|s| s.to_string())
                })
                .unwrap_or(body);
            Err(Error::Api {
                status: code,
                message,
            })
        }
    }

    async fn handle_no_content(&self, resp: Response) -> Result<()> {
        let status = resp.status();
        if status.is_success() {
            Ok(())
        } else {
            let code = status.as_u16();
            let message = resp.text().await.unwrap_or_else(|_| status.to_string());
            Err(Error::Api {
                status: code,
                message,
            })
        }
    }

    // ── Typed HTTP methods ────────────────────────────────────────────────────

    pub async fn get<T: DeserializeOwned>(&self, path: &str) -> Result<T> {
        let u = Arc::new(self.url(path));
        let v = self.api_version.clone();
        let resp = self
            .execute_with_retry(|client| {
                client
                    .get(u.as_str())
                    .header("Version", &v)
                    .header("Content-Type", "application/json")
            })
            .await?;
        self.handle_response(resp).await
    }

    pub async fn get_with_query<T: DeserializeOwned, Q: Serialize + ?Sized>(
        &self,
        path: &str,
        query: &Q,
    ) -> Result<T> {
        let u = Arc::new(self.url(path));
        let v = self.api_version.clone();
        // Serialize query params so the closure can be Fn + Send
        let qv = serde_json::to_value(query).map_err(Error::Json)?;
        let resp = self
            .execute_with_retry(move |client| {
                client
                    .get(u.as_str())
                    .header("Version", &v)
                    .header("Content-Type", "application/json")
                    .query(&qv)
            })
            .await?;
        self.handle_response(resp).await
    }

    pub async fn post<T: DeserializeOwned, B: Serialize>(&self, path: &str, body: &B) -> Result<T> {
        let u = Arc::new(self.url(path));
        let v = self.api_version.clone();
        let body_json = serde_json::to_value(body).map_err(Error::Json)?;
        let resp = self
            .execute_with_retry(move |client| {
                client
                    .post(u.as_str())
                    .header("Version", &v)
                    .json(&body_json)
            })
            .await?;
        self.handle_response(resp).await
    }

    pub async fn put<T: DeserializeOwned, B: Serialize>(&self, path: &str, body: &B) -> Result<T> {
        let u = Arc::new(self.url(path));
        let v = self.api_version.clone();
        let body_json = serde_json::to_value(body).map_err(Error::Json)?;
        let resp = self
            .execute_with_retry(move |client| {
                client
                    .put(u.as_str())
                    .header("Version", &v)
                    .json(&body_json)
            })
            .await?;
        self.handle_response(resp).await
    }

    pub async fn patch<T: DeserializeOwned, B: Serialize>(
        &self,
        path: &str,
        body: &B,
    ) -> Result<T> {
        let u = Arc::new(self.url(path));
        let v = self.api_version.clone();
        let body_json = serde_json::to_value(body).map_err(Error::Json)?;
        let resp = self
            .execute_with_retry(move |client| {
                client
                    .patch(u.as_str())
                    .header("Version", &v)
                    .json(&body_json)
            })
            .await?;
        self.handle_response(resp).await
    }

    pub async fn delete<T: DeserializeOwned>(&self, path: &str) -> Result<T> {
        let u = Arc::new(self.url(path));
        let v = self.api_version.clone();
        let resp = self
            .execute_with_retry(|client| client.delete(u.as_str()).header("Version", &v))
            .await?;
        self.handle_response(resp).await
    }

    pub async fn delete_with_body<T: DeserializeOwned, B: Serialize>(
        &self,
        path: &str,
        body: &B,
    ) -> Result<T> {
        let u = Arc::new(self.url(path));
        let v = self.api_version.clone();
        let body_json = serde_json::to_value(body).map_err(Error::Json)?;
        let resp = self
            .execute_with_retry(move |client| {
                client
                    .delete(u.as_str())
                    .header("Version", &v)
                    .json(&body_json)
            })
            .await?;
        self.handle_response(resp).await
    }

    pub async fn delete_no_content(&self, path: &str) -> Result<()> {
        let u = Arc::new(self.url(path));
        let v = self.api_version.clone();
        let resp = self
            .execute_with_retry(|client| client.delete(u.as_str()).header("Version", &v))
            .await?;
        self.handle_no_content(resp).await
    }

    // ── Raw escape-hatch methods ──────────────────────────────────────────────

    pub async fn get_raw(&self, path: &str) -> Result<Response> {
        let u = Arc::new(self.url(path));
        let v = self.api_version.clone();
        self.execute_with_retry(|client| {
            client
                .get(u.as_str())
                .header("Version", &v)
                .header("Content-Type", "application/json")
        })
        .await
    }

    pub async fn post_raw<B: Serialize>(&self, path: &str, body: &B) -> Result<Response> {
        let u = Arc::new(self.url(path));
        let v = self.api_version.clone();
        let body_json = serde_json::to_value(body).map_err(Error::Json)?;
        self.execute_with_retry(move |client| {
            client
                .post(u.as_str())
                .header("Version", &v)
                .json(&body_json)
        })
        .await
    }
}

fn exponential_backoff(retry: u32) -> Duration {
    let base_ms = 200u64 * 2u64.pow(retry);
    Duration::from_millis(base_ms.min(10_000))
}

fn jitter() -> Duration {
    let t = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .map(|d| d.as_nanos() as u64)
        .unwrap_or(0);
    let hash = t
        .wrapping_mul(6364136223846793005)
        .wrapping_add(1442695040888963407);
    Duration::from_millis(hash % 200)
}