quilt-rs 0.31.1

//! Host configuration functionality
//!
//! This module handles fetching and parsing host configuration from remote endpoints.

use serde::Deserialize;

use crate::Error;
use crate::Res;
use crate::checksum::MULTIHASH_CRC64_NVME;
use crate::checksum::MULTIHASH_SHA256_CHUNKED;
use crate::error::RemoteCatalogError;
use crate::io::remote::client::HttpClient;
use quilt_uri::Host;

/// Supported checksum algorithms for a host
#[derive(Clone, Debug, PartialEq, Eq)]
pub enum HostChecksums {
    /// CRC64 checksums (NVMe variant)
    Crc64,
    /// SHA256 checksums
    // Sha256, Legacy, we dont' use it
    /// SHA256 chunked checksums
    Sha256Chunked,
}

impl HostChecksums {
    /// Get the multihash algorithm code for this checksum type
    pub fn algorithm_code(&self) -> u64 {
        match self {
            HostChecksums::Crc64 => MULTIHASH_CRC64_NVME,
            HostChecksums::Sha256Chunked => MULTIHASH_SHA256_CHUNKED,
        }
    }
}

/// Configuration returned by a host
#[derive(Clone, Debug, PartialEq)]
pub struct HostConfig {
    /// Supported checksum algorithms
    pub checksums: HostChecksums,
    /// The host this configuration came from
    pub host: Option<Host>,
}

impl Default for HostConfig {
    fn default() -> Self {
        Self {
            checksums: HostChecksums::Sha256Chunked,
            host: None,
        }
    }
}

impl HostConfig {
    /// Create a HostConfig with CRC64 checksums
    pub fn default_crc64() -> Self {
        Self {
            checksums: HostChecksums::Crc64,
            host: None,
        }
    }

    /// Create a HostConfig with SHA256 chunked checksums
    pub fn default_sha256_chunked() -> Self {
        Self {
            checksums: HostChecksums::Sha256Chunked,
            host: None,
        }
    }
}

/// JSON response structure from host config endpoint
#[derive(Deserialize)]
struct ConfigResponse {
    #[serde(rename = "crc64Checksums")]
    crc64_checksums: Option<bool>,
}

/// Fetch host configuration from the given host
///
/// Makes a request to `https://${host}/config.json` and parses the response
/// to determine the supported checksum algorithms.
///
/// # Arguments
/// * `client` - HTTP client implementation to use for the request
/// * `host` - Host name (e.g. "open.quiltdata.com")
///
/// # Returns
/// * `Ok(HostConfig)` - Successfully parsed host configuration
/// * `Err(Error::RemoteCatalog(RemoteCatalogError::HostConfig(..)))` - Failed to fetch or parse configuration
/// * `Err(Error::Reqwest)` - HTTP request failed
/// * `Err(Error::Json)` - JSON parsing failed
pub async fn fetch_host_config(client: &impl HttpClient, host: &Option<Host>) -> Res<HostConfig> {
    match host {
        Some(host) => {
            let url = format!("https://{host}/config.json");

            let response: ConfigResponse = client.get(&url, None).await.map_err(|e| {
                Error::RemoteCatalog(RemoteCatalogError::HostConfig(format!(
                    "Failed to fetch config from {host}: {e}"
                )))
            })?;

            // Determine checksum algorithm based on crc64Checksums field
            let checksums = match response.crc64_checksums {
                Some(true) => HostChecksums::Crc64,
                Some(false) | None => HostChecksums::Sha256Chunked, // Default
            };

            Ok(HostConfig {
                checksums,
                host: Some(host.clone()),
            })
        }
        None => Ok(HostConfig::default()),
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    use async_trait::async_trait;
    use reqwest::header::HeaderMap;
    use serde::de::DeserializeOwned;
    use std::collections::HashMap;
    use test_log::test;

    // Mock HTTP client for testing
    struct MockHttpClient {
        responses: std::collections::HashMap<String, Result<String, String>>,
    }

    impl MockHttpClient {
        fn new() -> Self {
            Self {
                responses: HashMap::new(),
            }
        }

        fn add_response(&mut self, url: String, response: Result<String, String>) {
            self.responses.insert(url, response);
        }
    }

    #[async_trait]
    impl HttpClient for MockHttpClient {
        async fn get<T: DeserializeOwned>(&self, url: &str, _auth_token: Option<&str>) -> Res<T> {
            match self.responses.get(url) {
                Some(Ok(response_body)) => {
                    let response: T = serde_json::from_str(response_body)?;
                    Ok(response)
                }
                Some(Err(error)) => Err(Error::RemoteCatalog(RemoteCatalogError::HostConfig(
                    error.clone(),
                ))),
                None => Err(Error::RemoteCatalog(RemoteCatalogError::HostConfig(
                    format!("No mock response for URL: {url}"),
                ))),
            }
        }

        async fn head(&self, _url: &str) -> Res<HeaderMap> {
            unimplemented!("head not needed for host config tests")
        }

        async fn post<T: DeserializeOwned>(
            &self,
            _url: &str,
            _form_data: &HashMap<String, String>,
        ) -> Res<T> {
            unimplemented!("post not needed for host config tests")
        }

        async fn post_json<T: DeserializeOwned, B: serde::Serialize + Send + Sync>(
            &self,
            _url: &str,
            _body: &B,
        ) -> Res<T> {
            unimplemented!("post_json not needed for host config tests")
        }
    }

    #[test(tokio::test)]
    async fn test_fetch_host_config_crc64_enabled() -> Res<()> {
        let mut client = MockHttpClient::new();
        client.add_response(
            "https://test.quilt.dev/config.json".to_string(),
            Ok(r#"{"crc64Checksums": true}"#.to_string()),
        );

        let config = fetch_host_config(&client, &Some(Host::default())).await?;
        assert_eq!(config.checksums, HostChecksums::Crc64);

        Ok(())
    }

    #[test(tokio::test)]
    async fn test_fetch_host_config_crc64_disabled() -> Res<()> {
        let mut client = MockHttpClient::new();
        client.add_response(
            "https://test.quilt.dev/config.json".to_string(),
            Ok(r#"{"crc64Checksums": false}"#.to_string()),
        );

        let config = fetch_host_config(&client, &Some(Host::default())).await?;
        assert_eq!(config.checksums, HostChecksums::Sha256Chunked);

        Ok(())
    }

    #[test(tokio::test)]
    async fn test_fetch_host_config_crc64_missing() -> Res<()> {
        let mut client = MockHttpClient::new();
        client.add_response(
            "https://test.quilt.dev/config.json".to_string(),
            Ok(r"{}".to_string()),
        );

        let config = fetch_host_config(&client, &Some(Host::default())).await?;
        assert_eq!(config.checksums, HostChecksums::Sha256Chunked);

        Ok(())
    }

    #[test(tokio::test)]
    async fn test_fetch_host_config_other_fields_ignored() -> Res<()> {
        let mut client = MockHttpClient::new();
        client.add_response(
            "https://test.quilt.dev/config.json".to_string(),
            Ok(r#"{"crc64Checksums": true, "mode": "OPEN", "other": "ignored"}"#.to_string()),
        );

        let config = fetch_host_config(&client, &Some(Host::default())).await?;
        assert_eq!(config.checksums, HostChecksums::Crc64);

        Ok(())
    }

    #[test(tokio::test)]
    async fn test_fetch_host_config_network_error() {
        let mut client = MockHttpClient::new();
        client.add_response(
            "https://test.quilt.dev/config.json".to_string(),
            Err("Network error".to_string()),
        );

        let result = fetch_host_config(&client, &Some(Host::default())).await;
        assert!(result.is_err());
        assert!(result.unwrap_err().to_string().contains("Network error"));
    }

    #[test(tokio::test)]
    async fn test_fetch_host_config_invalid_json() {
        let mut client = MockHttpClient::new();
        client.add_response(
            "https://test.quilt.dev/config.json".to_string(),
            Ok(r"invalid json".to_string()),
        );

        let result = fetch_host_config(&client, &Some(Host::default())).await;
        assert!(result.is_err());

        // JSON parsing errors get wrapped in HostConfig error by map_err
        let error = result.unwrap_err();
        match error {
            Error::RemoteCatalog(RemoteCatalogError::HostConfig(msg))
                if msg.contains("JSON error") =>
            {
                // This is expected - all client errors get wrapped
            }
            _ => panic!("Expected HostConfig error wrapping JSON error, got: {error:?}"),
        }
    }

    #[test(tokio::test)]
    async fn test_fetch_host_config_none() -> Res<()> {
        let client = MockHttpClient::new();
        let config = fetch_host_config(&client, &None).await?;
        assert_eq!(config, HostConfig::default());
        Ok(())
    }
}