openapi-contract 0.1.0

use std::marker::PhantomData;

use futures_core::Stream;
use serde::de::DeserializeOwned;

use crate::client::{ApiClient, Method};
use crate::error::{ApiError, DefinedErrorBody};
use crate::sse::SseEvent;

fn parse_error_response(status: u16, body: String) -> ApiError {
    if let Ok(parsed) = serde_json::from_str::<DefinedErrorBody>(&body) {
        if parsed.defined && !parsed.code.is_empty() {
            return ApiError::Defined {
                status,
                code: parsed.code,
                message: parsed.message,
            };
        }
    }
    ApiError::Api {
        status,
        message: body,
    }
}

/// A type-safe API request built by the `api!` macro.
///
/// `T` is the expected response type, inferred from the OpenAPI spec at compile time.
pub struct ApiRequest<T> {
    pub method: Method,
    pub path: String,
    pub query: Option<String>,
    pub body: Option<String>,
    pub _marker: PhantomData<T>,
}

impl<T> ApiRequest<T> {
    pub fn new(method: Method, path: String) -> Self {
        Self {
            method,
            path,
            query: None,
            body: None,
            _marker: PhantomData,
        }
    }

    pub fn query_raw(mut self, qs: impl Into<String>) -> Self {
        self.query = Some(qs.into());
        self
    }

    pub fn body_json(mut self, body: &impl serde::Serialize) -> Self {
        self.body = Some(serde_json::to_string(body).expect("request body must be serializable"));
        self
    }

    /// Set a pre-serialized JSON body. Returns an error if serialization fails.
    pub fn try_body_json(mut self, body: &impl serde::Serialize) -> Result<Self, ApiError> {
        self.body = Some(serde_json::to_string(body)?);
        Ok(self)
    }
}

impl<T: DeserializeOwned> ApiRequest<T> {
    /// Execute the request and deserialize the response.
    pub async fn fetch(self, client: &(impl ApiClient + ?Sized)) -> Result<T, ApiError> {
        let resp = client
            .request(self.method, &self.path, self.query.as_deref(), self.body)
            .await?;

        let status = resp.status();
        if !status.is_success() {
            let body = resp.text().await.unwrap_or_default();
            return Err(parse_error_response(status.as_u16(), body));
        }

        let text = resp.text().await?;
        if text.is_empty() {
            return serde_json::from_str("null").map_err(ApiError::from);
        }
        serde_json::from_str(&text).map_err(ApiError::from)
    }
}

impl ApiRequest<()> {
    /// Execute a request that returns no body (e.g. DELETE, PUT with 204).
    pub async fn fetch_empty(self, client: &(impl ApiClient + ?Sized)) -> Result<(), ApiError> {
        let resp = client
            .request(self.method, &self.path, self.query.as_deref(), self.body)
            .await?;

        let status = resp.status();
        if !status.is_success() {
            let body = resp.text().await.unwrap_or_default();
            return Err(parse_error_response(status.as_u16(), body));
        }
        Ok(())
    }
}

impl<T> ApiRequest<T> {
    /// Execute the request and return an SSE event stream.
    pub async fn fetch_stream(
        self,
        client: &(impl ApiClient + ?Sized),
    ) -> Result<impl Stream<Item = Result<SseEvent, ApiError>>, ApiError> {
        let stream = client
            .request_stream(self.method, &self.path, self.query.as_deref())
            .await?;
        Ok(stream)
    }
}

fn percent_encode(input: &str) -> String {
    let mut out = String::with_capacity(input.len());
    for byte in input.bytes() {
        match byte {
            b'A'..=b'Z' | b'a'..=b'z' | b'0'..=b'9' | b'-' | b'_' | b'.' | b'~' => {
                out.push(byte as char);
            }
            _ => {
                out.push('%');
                out.push_str(&format!("{:02X}", byte));
            }
        }
    }
    out
}

/// Build a URL-encoded query string from key-value pairs.
pub fn build_query_string(pairs: &[(&str, &dyn ToString)]) -> String {
    pairs
        .iter()
        .map(|(k, v)| format!("{}={}", percent_encode(k), percent_encode(&v.to_string())))
        .collect::<Vec<_>>()
        .join("&")
}

#[cfg(test)]
#[allow(clippy::manual_async_fn)]
mod tests {
    use super::*;
    use crate::sse::SseStream;
    use tokio::io::AsyncWriteExt;
    use tokio::time::{sleep, Duration};

    // ── Helpers ─────────────────────────────────────────────────

    async fn mock_response(status: u16, body: &str) -> reqwest::Response {
        let mut server = mockito::Server::new_async().await;
        let _mock = server
            .mock("GET", "/mock")
            .with_status(status as usize)
            .with_header("content-type", "application/json")
            .with_body(body)
            .create_async()
            .await;
        reqwest::get(&format!("{}/mock", server.url()))
            .await
            .unwrap()
    }

    fn make_reqwest_error() -> reqwest::Error {
        reqwest::Client::new()
            .get("http://localhost:1/x")
            .header("bad\0header", "v")
            .build()
            .unwrap_err()
    }

    async fn malformed_chunked_response() -> reqwest::Response {
        let listener = tokio::net::TcpListener::bind("127.0.0.1:0").await.unwrap();
        let addr = listener.local_addr().unwrap();
        let server = tokio::spawn(async move {
            let (mut socket, _) = listener.accept().await.unwrap();
            socket
                .write_all(
                    b"HTTP/1.1 200 OK\r\n\
Content-Type: application/json\r\n\
Content-Length: 40\r\n\
Connection: close\r\n\
\r\n\
{}",
                )
                .await
                .unwrap();
            sleep(Duration::from_millis(250)).await;
            socket.shutdown().await.unwrap();
        });
        let resp = reqwest::get(format!("http://{addr}")).await.unwrap();
        let _ = server.await;
        resp
    }

    struct MockClient {
        status: u16,
        body: String,
    }
    struct FailingClient;
    struct MalformedBodyClient;

    impl ApiClient for MockClient {
        fn request(
            &self,
            _: Method,
            _: &str,
            _: Option<&str>,
            _: Option<String>,
        ) -> impl std::future::Future<Output = Result<reqwest::Response, ApiError>> + Send {
            let status = self.status;
            let body = self.body.clone();
            async move { Ok(mock_response(status, &body).await) }
        }
        fn request_stream(
            &self,
            _: Method,
            _: &str,
            _: Option<&str>,
        ) -> impl std::future::Future<Output = Result<SseStream, ApiError>> + Send {
            async move {
                let chunks: Vec<Result<bytes::Bytes, reqwest::Error>> =
                    vec![Ok(bytes::Bytes::from(&b"data: hi\n\n"[..]))];
                Ok(SseStream::new(Box::pin(futures_util::stream::iter(chunks))))
            }
        }
    }

    impl ApiClient for FailingClient {
        fn request(
            &self,
            _: Method,
            _: &str,
            _: Option<&str>,
            _: Option<String>,
        ) -> impl std::future::Future<Output = Result<reqwest::Response, ApiError>> + Send {
            async { Err(ApiError::Http(make_reqwest_error())) }
        }
        fn request_stream(
            &self,
            _: Method,
            _: &str,
            _: Option<&str>,
        ) -> impl std::future::Future<Output = Result<SseStream, ApiError>> + Send {
            async { Err(ApiError::Http(make_reqwest_error())) }
        }
    }

    impl ApiClient for MalformedBodyClient {
        fn request(
            &self,
            _: Method,
            _: &str,
            _: Option<&str>,
            _: Option<String>,
        ) -> impl std::future::Future<Output = Result<reqwest::Response, ApiError>> + Send {
            async { Ok(malformed_chunked_response().await) }
        }
        fn request_stream(
            &self,
            _: Method,
            _: &str,
            _: Option<&str>,
        ) -> impl std::future::Future<Output = Result<SseStream, ApiError>> + Send {
            async { Err(ApiError::Http(make_reqwest_error())) }
        }
    }

    // ── Builder tests ───────────────────────────────────────────

    #[test]
    fn api_request_builder() {
        // new
        let req = ApiRequest::<String>::new(Method::GET, "/test".into());
        assert_eq!(req.method, Method::GET);
        assert_eq!(req.path, "/test");
        assert!(req.query.is_none());
        assert!(req.body.is_none());

        // chaining query + body
        let body = serde_json::json!({"x": 1});
        let req = ApiRequest::<String>::new(Method::POST, "/x".into())
            .query_raw("q=1")
            .body_json(&body);
        assert_eq!(req.query.as_deref(), Some("q=1"));
        assert_eq!(req.body.as_deref(), Some(r#"{"x":1}"#));
    }

    #[test]
    fn body_serialization() {
        // try_body_json success
        let req = ApiRequest::<String>::new(Method::POST, "/t".into())
            .try_body_json(&serde_json::json!({"x": 1}))
            .unwrap();
        assert!(req.body.is_some());

        // try_body_json failure
        #[derive(Debug)]
        struct Bad;
        impl serde::Serialize for Bad {
            fn serialize<S: serde::Serializer>(&self, _: S) -> Result<S::Ok, S::Error> {
                Err(serde::ser::Error::custom("fail"))
            }
        }
        assert!(ApiRequest::<String>::new(Method::POST, "/t".into())
            .try_body_json(&Bad)
            .is_err());
    }

    #[test]
    #[should_panic(expected = "request body must be serializable")]
    fn body_json_panics_on_bad_input() {
        #[derive(Debug)]
        struct Bad;
        impl serde::Serialize for Bad {
            fn serialize<S: serde::Serializer>(&self, _: S) -> Result<S::Ok, S::Error> {
                Err(serde::ser::Error::custom("fail"))
            }
        }
        let _ = ApiRequest::<String>::new(Method::POST, "/t".into()).body_json(&Bad);
    }

    #[test]
    fn query_string_and_percent_encode() {
        assert_eq!(build_query_string(&[]), "");
        assert_eq!(build_query_string(&[("limit", &10)]), "limit=10");
        assert_eq!(
            build_query_string(&[("a", &"hello"), ("b", &42)]),
            "a=hello&b=42"
        );
        assert_eq!(
            build_query_string(&[("q", &"hello world"), ("x", &"a&b=c")]),
            "q=hello%20world&x=a%26b%3Dc"
        );
        assert_eq!(percent_encode("abc-_.~123"), "abc-_.~123");
        assert_eq!(percent_encode("&="), "%26%3D");
    }

    // ── fetch tests ─────────────────────────────────────────────

    #[tokio::test]
    async fn fetch_success_and_edge_cases() {
        // Normal success
        let client = MockClient {
            status: 200,
            body: r#""hello""#.into(),
        };
        assert_eq!(
            ApiRequest::<String>::new(Method::GET, "/t".into())
                .fetch(&client)
                .await
                .unwrap(),
            "hello"
        );

        // Empty body → null
        let client = MockClient {
            status: 200,
            body: String::new(),
        };
        let result: Option<String> = ApiRequest::new(Method::GET, "/t".into())
            .fetch(&client)
            .await
            .unwrap();
        assert_eq!(result, None);

        // Deserialization error
        let client = MockClient {
            status: 200,
            body: "not-json".into(),
        };
        assert!(ApiRequest::<i32>::new(Method::GET, "/t".into())
            .fetch(&client)
            .await
            .unwrap_err()
            .to_string()
            .starts_with("serialization error:"));
    }

    #[tokio::test]
    async fn fetch_error_responses() {
        // Plain API error
        let client = MockClient {
            status: 403,
            body: "forbidden".into(),
        };
        let err = ApiRequest::<String>::new(Method::GET, "/t".into())
            .fetch(&client)
            .await
            .unwrap_err();
        assert!(matches!(err, ApiError::Api { status: 403, .. }));

        // Defined error
        let client = MockClient {
            status: 404,
            body: r#"{"defined":true,"code":"TEAM_NOT_FOUND","message":"Team not found"}"#.into(),
        };
        let err = ApiRequest::<String>::new(Method::GET, "/t".into())
            .fetch(&client)
            .await
            .unwrap_err();
        assert!(err.is_code("TEAM_NOT_FOUND"));
        assert_eq!(err.status(), Some(404));

        // Non-defined JSON fallback
        let client = MockClient {
            status: 400,
            body: r#"{"defined":false,"code":"NOPE","message":"nope"}"#.into(),
        };
        let err = ApiRequest::<String>::new(Method::GET, "/t".into())
            .fetch(&client)
            .await
            .unwrap_err();
        assert!(matches!(err, ApiError::Api { status: 400, .. }));
        assert_eq!(err.code(), None);
    }

    #[tokio::test]
    async fn fetch_empty_success_and_errors() {
        // Success
        let client = MockClient {
            status: 204,
            body: String::new(),
        };
        assert!(ApiRequest::<()>::new(Method::DELETE, "/t".into())
            .fetch_empty(&client)
            .await
            .is_ok());

        // API error
        let client = MockClient {
            status: 500,
            body: "oops".into(),
        };
        assert!(matches!(
            ApiRequest::<()>::new(Method::DELETE, "/t".into())
                .fetch_empty(&client)
                .await
                .unwrap_err(),
            ApiError::Api { status: 500, .. }
        ));

        // Defined error
        let client = MockClient {
            status: 403,
            body: r#"{"defined":true,"code":"FORBIDDEN","message":"no access"}"#.into(),
        };
        let err = ApiRequest::<()>::new(Method::DELETE, "/t".into())
            .fetch_empty(&client)
            .await
            .unwrap_err();
        assert!(err.is_code("FORBIDDEN"));

        // Request error propagation
        assert!(ApiRequest::<()>::new(Method::DELETE, "/t".into())
            .fetch_empty(&FailingClient)
            .await
            .unwrap_err()
            .to_string()
            .starts_with("HTTP error:"));
    }

    #[tokio::test]
    async fn fetch_stream_success_and_errors() {
        use futures_util::StreamExt;

        // Success
        let client = MockClient {
            status: 200,
            body: String::new(),
        };
        let mut stream = ApiRequest::<()>::new(Method::GET, "/sse".into())
            .fetch_stream(&client)
            .await
            .unwrap();
        assert_eq!(stream.next().await.unwrap().unwrap().data, "hi");

        // Request error propagation
        assert!(ApiRequest::<()>::new(Method::GET, "/sse".into())
            .fetch_stream(&FailingClient)
            .await
            .is_err());
    }

    #[tokio::test]
    async fn fetch_propagates_body_read_error() {
        let err = ApiRequest::<String>::new(Method::GET, "/t".into())
            .fetch(&MalformedBodyClient)
            .await
            .unwrap_err();
        assert!(err.to_string().starts_with("HTTP error:"));
    }
}