// file: khbb_lib/src/solana_rpc_http.rs

//! Minimal Solana HTTP JSON-RPC client.
//!
//! This module intentionally avoids the high-level Solana RPC client and uses
//! plain `reqwest` with explicit JSON-RPC request and response handling.

/// Configuration of the minimal Solana HTTP RPC client.
#[derive(Debug, Clone)]
pub struct KhbbSolanaHttpRpcClientConfig {
    /// Base HTTP RPC endpoint.
    pub url: std::string::String,
}

/// Minimal JSON-RPC request envelope.
#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
#[serde(bound(
    serialize = "TParams: serde::Serialize",
    deserialize = "TParams: serde::de::DeserializeOwned"
))]
pub struct KhbbJsonRpcRequestEnvelope<TParams>
where
    TParams: serde::Serialize,
{
    /// JSON-RPC protocol version.
    pub jsonrpc: std::string::String,
    /// RPC method name.
    pub method: std::string::String,
    /// RPC parameters.
    pub params: TParams,
    /// Request identifier.
    pub id: u64,
}

/// Minimal JSON-RPC response envelope.
///
/// The Solana-specific result payload should use official types from
/// `solana-rpc-client-api::response` whenever they exist.
#[derive(Debug, Clone, serde::Serialize, serde::Deserialize)]
#[serde(bound(
    serialize = "TResult: serde::Serialize",
    deserialize = "TResult: serde::de::DeserializeOwned"
))]
pub struct KhbbJsonRpcResponseEnvelope<TResult>
where
    TResult: serde::Serialize + serde::de::DeserializeOwned,
{
    /// JSON-RPC protocol version.
    pub jsonrpc: std::string::String,
    /// Successful result if present.
    pub result: std::option::Option<TResult>,
    /// Raw error object if present.
    pub error: std::option::Option<serde_json::Value>,
    /// Response identifier.
    pub id: serde_json::Value,
}

/// HTTP RPC response bundle containing both raw and parsed payloads.
pub struct KhbbHttpRpcCallOutput<TResult>
where
    TResult: serde::Serialize + serde::de::DeserializeOwned,
{
    /// Serialized request body sent to the server.
    pub request_body: std::string::String,
    /// Raw response body received from the server.
    pub response_body: std::string::String,
    /// Parsed JSON-RPC response.
    pub response: KhbbJsonRpcResponseEnvelope<TResult>,
}

/// Minimal Solana HTTP JSON-RPC client.
#[derive(Debug, Clone)]
pub struct KhbbSolanaHttpRpcClient {
    /// Request client.
    pub(crate) http_client: reqwest::Client,
    /// Client configuration.
    pub(crate) config: KhbbSolanaHttpRpcClientConfig,
}

impl KhbbSolanaHttpRpcClient {
    /// Creates a new minimal Solana HTTP JSON-RPC client.
    pub fn new(
        config: KhbbSolanaHttpRpcClientConfig,
    ) -> core::result::Result<Self, crate::KhbbError> {
        if config.url.trim().is_empty() {
            return Err(crate::KhbbError::Config {
                message: std::string::String::from("solana http rpc client url must not be empty"),
            });
        }
        let builder = reqwest::Client::builder();
        let build_result = builder.build();
        let http_client = match build_result {
            Ok(value) => value,
            Err(error) => {
                return Err(crate::KhbbError::Runtime {
                    context: "build reqwest client",
                    message: error.to_string(),
                });
            },
        };
        Ok(Self { http_client, config })
    }

    /// Sends a generic JSON-RPC request.
    pub async fn send_json_rpc_request<TResult, TParams>(
        &self,
        rpc_request: solana_rpc_client_api::request::RpcRequest,
        params: TParams,
        id: u64,
    ) -> core::result::Result<KhbbHttpRpcCallOutput<TResult>, crate::KhbbError>
    where
        TResult: serde::Serialize + serde::de::DeserializeOwned,
        TParams: serde::Serialize,
    {
        let request_result = build_json_rpc_request(rpc_request, params, id);
        let request = match request_result {
            Ok(value) => value,
            Err(error) => {
                return Err(error);
            },
        };
        let request_body_result = serde_json::to_string(&request);
        let request_body = match request_body_result {
            Ok(value) => value,
            Err(error) => {
                return Err(crate::KhbbError::Json {
                    context: "serialize json rpc request",
                    message: error.to_string(),
                });
            },
        };
        let send_result = self
            .http_client
            .post(&self.config.url)
            .header(reqwest::header::CONTENT_TYPE, "application/json")
            .body(request_body.clone())
            .send()
            .await;
        let response = match send_result {
            Ok(value) => value,
            Err(error) => {
                return Err(crate::KhbbError::Runtime {
                    context: "send json rpc http request",
                    message: error.to_string(),
                });
            },
        };
        let response_text_result = response.text().await;
        let response_body = match response_text_result {
            Ok(value) => value,
            Err(error) => {
                return Err(crate::KhbbError::Runtime {
                    context: "read json rpc http response body",
                    message: error.to_string(),
                });
            },
        };
        let parse_result = parse_json_rpc_response::<TResult>(&response_body);
        let parsed_response = match parse_result {
            Ok(value) => value,
            Err(error) => {
                return Err(error);
            },
        };
        if parsed_response.error.is_some() {
            return Err(crate::KhbbError::Runtime {
                context: "json rpc server returned error",
                message: response_body.clone(),
            });
        }
        Ok(KhbbHttpRpcCallOutput {
            request_body,
            response_body,
            response: parsed_response,
        })
    }

    /// Calls the `getHealth` RPC method.
    pub async fn get_health(
        &self,
        id: u64,
    ) -> core::result::Result<KhbbHttpRpcCallOutput<std::string::String>, crate::KhbbError> {
        self.send_json_rpc_request::<std::string::String, std::vec::Vec<serde_json::Value>>(
            solana_rpc_client_api::request::RpcRequest::GetHealth,
            vec![],
            id,
        )
        .await
    }

    /// Calls the `getSlot` RPC method.
    pub async fn get_slot(
        &self,
        id: u64,
    ) -> core::result::Result<KhbbHttpRpcCallOutput<u64>, crate::KhbbError> {
        self.send_json_rpc_request::<u64, std::vec::Vec<serde_json::Value>>(
            solana_rpc_client_api::request::RpcRequest::GetSlot,
            vec![],
            id,
        )
        .await
    }

    /// Calls the `getVersion` RPC method.
    pub async fn get_version(
        &self,
        id: u64,
    ) -> core::result::Result<
        KhbbHttpRpcCallOutput<solana_rpc_client_api::response::RpcVersionInfo>,
        crate::KhbbError,
    > {
        self.send_json_rpc_request::<
            solana_rpc_client_api::response::RpcVersionInfo,
            std::vec::Vec<serde_json::Value>,
        >(
            solana_rpc_client_api::request::RpcRequest::GetVersion,
            vec![],
            id,
        )
        .await
    }
}

pub(crate) fn rpc_request_method_name(
    rpc_request: solana_rpc_client_api::request::RpcRequest,
) -> core::result::Result<&'static str, crate::KhbbError> {
    match rpc_request {
        solana_rpc_client_api::request::RpcRequest::GetHealth => Ok("getHealth"),
        solana_rpc_client_api::request::RpcRequest::GetSlot => Ok("getSlot"),
        solana_rpc_client_api::request::RpcRequest::GetVersion => Ok("getVersion"),
        _ => Err(crate::KhbbError::Config {
            message: std::format!(
                "unsupported rpc request variant in khbb minimal http client: {:?}",
                rpc_request
            ),
        }),
    }
}

/// Builds a minimal JSON-RPC request object.
pub(crate) fn build_json_rpc_request<TParams>(
    rpc_request: solana_rpc_client_api::request::RpcRequest,
    params: TParams,
    id: u64,
) -> core::result::Result<KhbbJsonRpcRequestEnvelope<TParams>, crate::KhbbError>
where
    TParams: serde::Serialize,
{
    let method_name_result = rpc_request_method_name(rpc_request);
    let method_name = match method_name_result {
        Ok(value) => value,
        Err(error) => {
            return Err(error);
        },
    };
    Ok(KhbbJsonRpcRequestEnvelope {
        jsonrpc: std::string::String::from("2.0"),
        method: std::string::String::from(method_name),
        params,
        id,
    })
}

/// Parses a minimal JSON-RPC response body.
pub(crate) fn parse_json_rpc_response<TResult>(
    response_body: &str,
) -> core::result::Result<KhbbJsonRpcResponseEnvelope<TResult>, crate::KhbbError>
where
    TResult: serde::Serialize + serde::de::DeserializeOwned,
{
    let parse_result = serde_json::from_str::<KhbbJsonRpcResponseEnvelope<TResult>>(response_body);
    match parse_result {
        Ok(value) => Ok(value),
        Err(error) => Err(crate::KhbbError::Json {
            context: "parse json rpc response",
            message: error.to_string(),
        }),
    }
}

#[cfg(test)]
mod tests {
    #[test]
    fn rpc_request_method_name_maps_supported_variants() {
        let get_health_result =
            super::rpc_request_method_name(solana_rpc_client_api::request::RpcRequest::GetHealth);
        let get_slot_result =
            super::rpc_request_method_name(solana_rpc_client_api::request::RpcRequest::GetSlot);
        let get_version_result =
            super::rpc_request_method_name(solana_rpc_client_api::request::RpcRequest::GetVersion);
        assert!(get_health_result.is_ok());
        assert!(get_slot_result.is_ok());
        assert!(get_version_result.is_ok());
        assert_eq!(get_health_result.expect("getHealth"), "getHealth");
        assert_eq!(get_slot_result.expect("getSlot"), "getSlot");
        assert_eq!(get_version_result.expect("getVersion"), "getVersion");
    }

    #[test]
    fn build_json_rpc_request_sets_expected_fields() {
        let request_result = super::build_json_rpc_request(
            solana_rpc_client_api::request::RpcRequest::GetSlot,
            std::vec::Vec::<serde_json::Value>::new(),
            7,
        );
        assert!(request_result.is_ok());
        let request = request_result.expect("build request");
        assert_eq!(request.jsonrpc, "2.0");
        assert_eq!(request.method, "getSlot");
        assert_eq!(request.id, 7);
        assert!(request.params.is_empty());
    }

    #[test]
    fn parse_json_rpc_response_accepts_u64_success_payload() {
        let body = r#"{
            "jsonrpc":"2.0",
            "result":123456,
            "id":1
        }"#;
        let result = super::parse_json_rpc_response::<u64>(body);
        assert!(result.is_ok());
        let response = result.expect("parse success response");
        assert_eq!(response.jsonrpc, "2.0");
        assert_eq!(response.result, Some(123456));
        assert!(response.error.is_none());
    }

    #[test]
    fn parse_json_rpc_response_accepts_string_success_payload() {
        let body = r#"{
            "jsonrpc":"2.0",
            "result":"ok",
            "id":1
        }"#;
        let result = super::parse_json_rpc_response::<std::string::String>(body);
        assert!(result.is_ok());
        let response = result.expect("parse string response");
        assert_eq!(response.result.as_deref(), Some("ok"));
        assert!(response.error.is_none());
    }

    #[test]
    fn parse_json_rpc_response_accepts_error_payload() {
        let body = r#"{
            "jsonrpc":"2.0",
            "error":{"code":-32000,"message":"failure","data":null},
            "id":1
        }"#;
        let result = super::parse_json_rpc_response::<u64>(body);
        assert!(result.is_ok());
        let response = result.expect("parse error response");
        assert!(response.result.is_none());
        assert!(response.error.is_some());
    }

    #[test]
    fn parse_json_rpc_response_accepts_rpc_version_info_payload() {
        let body = r#"{
            "jsonrpc":"2.0",
            "result":{"solana-core":"2.3.3","feature-set":123},
            "id":1
        }"#;
        let result =
            super::parse_json_rpc_response::<solana_rpc_client_api::response::RpcVersionInfo>(body);
        assert!(result.is_ok());
        let response = result.expect("parse rpc version info response");
        assert!(response.result.is_some());
        assert!(response.error.is_none());
    }

    #[test]
    fn parse_json_rpc_response_rejects_invalid_json() {
        let body = r#"not-json"#;
        let result = super::parse_json_rpc_response::<u64>(body);
        assert!(result.is_err());
    }

    #[test]
    fn new_rejects_empty_url() {
        let config = super::KhbbSolanaHttpRpcClientConfig { url: std::string::String::new() };
        let result = super::KhbbSolanaHttpRpcClient::new(config);
        assert!(result.is_err());
    }

    #[test]
    fn new_accepts_valid_url() {
        let config = super::KhbbSolanaHttpRpcClientConfig {
            url: std::string::String::from("https://example.invalid"),
        };
        let result = super::KhbbSolanaHttpRpcClient::new(config);
        assert!(result.is_ok());
    }
}