finance-query 2.5.0

//! Financial Modeling Prep API client with rate limiting.

use std::sync::Arc;
use std::time::Duration;

use reqwest::{Client, StatusCode};
use serde::de::DeserializeOwned;
use serde_json::Value;
use tracing::debug;

use crate::error::{FinanceError, Result};
use crate::rate_limiter::RateLimiter;

const FMP_BASE: &str = "https://financialmodelingprep.com";
const DEFAULT_TIMEOUT: Duration = Duration::from_secs(30);

pub(crate) struct FmpClientBuilder {
    api_key: String,
    timeout: Duration,
    base_url: Option<String>,
}

impl FmpClientBuilder {
    pub fn new(api_key: impl Into<String>) -> Self {
        Self {
            api_key: api_key.into(),
            timeout: DEFAULT_TIMEOUT,
            base_url: None,
        }
    }

    pub fn timeout(mut self, timeout: Duration) -> Self {
        self.timeout = timeout;
        self
    }

    #[cfg(test)]
    pub fn base_url(mut self, url: impl Into<String>) -> Self {
        self.base_url = Some(url.into());
        self
    }

    pub(super) fn build_with_limiter(self, limiter: Arc<RateLimiter>) -> Result<FmpClient> {
        let http = Client::builder()
            .timeout(self.timeout)
            .user_agent(format!(
                "finance-query/{} (https://github.com/Verdenroz/finance-query)",
                env!("CARGO_PKG_VERSION")
            ))
            .build()?;

        Ok(FmpClient {
            api_key: self.api_key,
            http,
            limiter,
            base_url: self.base_url.unwrap_or_else(|| FMP_BASE.to_string()),
        })
    }
}

/// Financial Modeling Prep API client. Constructed per-call via the module singleton.
pub(crate) struct FmpClient {
    api_key: String,
    http: Client,
    limiter: Arc<RateLimiter>,
    base_url: String,
}

impl FmpClient {
    fn check_status(status: StatusCode) -> Result<()> {
        match status {
            StatusCode::OK => Ok(()),
            StatusCode::UNAUTHORIZED | StatusCode::FORBIDDEN => {
                Err(FinanceError::AuthenticationFailed {
                    context: "FMP API key invalid or missing. Call fmp::init(key) first."
                        .to_string(),
                })
            }
            StatusCode::NOT_FOUND => Err(FinanceError::SymbolNotFound {
                symbol: None,
                context: "Resource not found on FMP".to_string(),
            }),
            StatusCode::TOO_MANY_REQUESTS => Err(FinanceError::RateLimited {
                retry_after: Some(60),
            }),
            s if s.is_server_error() => Err(FinanceError::ServerError {
                status: s.as_u16(),
                context: "FMP server error".to_string(),
            }),
            s => Err(FinanceError::ExternalApiError {
                api: "FMP".to_string(),
                status: s.as_u16(),
            }),
        }
    }

    fn check_body_error(json: &Value) -> Result<()> {
        // FMP returns errors as {"Error Message": "..."} with 200 status
        if let Some(msg) = json.get("Error Message").and_then(|v| v.as_str()) {
            return Err(FinanceError::InvalidParameter {
                param: "request".to_string(),
                reason: msg.to_string(),
            });
        }
        Ok(())
    }

    /// Execute a GET request to an FMP REST path and return raw JSON.
    pub async fn get_raw(&self, path: &str, params: &[(&str, &str)]) -> Result<Value> {
        self.limiter.acquire().await;

        let url = format!("{}{}", self.base_url, path);
        let mut query: Vec<(&str, &str)> = vec![("apikey", &self.api_key)];
        query.extend_from_slice(params);

        debug!("FMP request: {path}");
        let resp = self.http.get(&url).query(&query).send().await?;

        Self::check_status(resp.status())?;

        let json: Value = resp.json().await?;
        Self::check_body_error(&json)?;

        Ok(json)
    }

    /// GET and deserialize into `T` directly.
    pub async fn get<T: DeserializeOwned>(&self, path: &str, params: &[(&str, &str)]) -> Result<T> {
        let json = self.get_raw(path, params).await?;
        serde_json::from_value(json).map_err(|e| FinanceError::ResponseStructureError {
            field: "response".to_string(),
            context: format!("Failed to deserialize FMP response: {e}"),
        })
    }
}