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// Code adapted from: https://github.com/althea-net/guac_rs/tree/master/web3/src/jsonrpc
use crate::{provider::ProviderError, JsonRpcClient};

use async_trait::async_trait;
use reqwest::{Client, Error as ReqwestError};
use serde::{de::DeserializeOwned, Serialize};
use std::{
    str::FromStr,
    sync::atomic::{AtomicU64, Ordering},
};
use thiserror::Error;
use url::Url;

use super::common::{JsonRpcError, Request, Response};

/// A low-level JSON-RPC Client over HTTP.
///
/// # Example
///
/// ```no_run
/// use ethers::{types::U64, providers::{JsonRpcClient, Http}};
/// use std::str::FromStr;
///
/// # async fn foo() -> Result<(), Box<dyn std::error::Error>> {
/// let provider = Http::from_str("http://localhost:8545")?;
/// let block_number: U64 = provider.request("eth_blockNumber", ()).await?;
/// # Ok(())
/// # }
/// ```
#[derive(Debug)]
pub struct Provider {
    id: AtomicU64,
    client: Client,
    url: Url,
}

#[derive(Error, Debug)]
/// Error thrown when sending an HTTP request
pub enum ClientError {
    /// Thrown if the request failed
    #[error(transparent)]
    ReqwestError(#[from] ReqwestError),
    #[error(transparent)]
    /// Thrown if the response could not be parsed
    JsonRpcError(#[from] JsonRpcError),

    #[error("Deserialization Error: {err}. Response: {text}")]
    /// Serde JSON Error
    SerdeJson {
        err: serde_json::Error,
        text: String,
    },
}

impl From<ClientError> for ProviderError {
    fn from(src: ClientError) -> Self {
        ProviderError::JsonRpcClientError(Box::new(src))
    }
}

#[async_trait]
impl JsonRpcClient for Provider {
    type Error = ClientError;

    /// Sends a POST request with the provided method and the params serialized as JSON
    /// over HTTP
    async fn request<T: Serialize + Send + Sync, R: DeserializeOwned>(
        &self,
        method: &str,
        params: T,
    ) -> Result<R, ClientError> {
        let next_id = self.id.load(Ordering::SeqCst) + 1;
        self.id.store(next_id, Ordering::SeqCst);

        let payload = Request::new(next_id, method, params);

        let res = self
            .client
            .post(self.url.as_ref())
            .json(&payload)
            .send()
            .await?;
        let text = res.text().await?;
        let res: Response<R> =
            serde_json::from_str(&text).map_err(|err| ClientError::SerdeJson { err, text })?;

        Ok(res.data.into_result()?)
    }
}

impl Provider {
    /// Initializes a new HTTP Client
    ///
    /// # Example
    ///
    /// ```
    /// use ethers::providers::Http;
    /// use url::Url;
    ///
    /// let url = Url::parse("http://localhost:8545").unwrap();
    /// let provider = Http::new(url);
    /// ```
    pub fn new(url: impl Into<Url>) -> Self {
        Self {
            id: AtomicU64::new(0),
            client: Client::new(),
            url: url.into(),
        }
    }
}

impl FromStr for Provider {
    type Err = url::ParseError;

    fn from_str(src: &str) -> Result<Self, Self::Err> {
        let url = Url::parse(src)?;
        Ok(Provider::new(url))
    }
}

impl Clone for Provider {
    fn clone(&self) -> Self {
        Self {
            id: AtomicU64::new(0),
            client: self.client.clone(),
            url: self.url.clone(),
        }
    }
}