commit-bridge 0.1.0

//! Operations to fetch and extract git branch data from remote repositories.

use crate::{domain::CommitHash, error::CommitHashError};
use async_trait::async_trait;

/// Allows running git commands.
#[async_trait]
pub trait GitFetcher: Send + Sync {
    /// Returns the latest hash of a git branch.
    async fn get_latest_hash(
        &self,
        repo_url: &str,
        branch: &str,
    ) -> Result<CommitHash, CommitHashError>;
}

/// Runs git commands.
pub struct MainGitFetcher;

#[async_trait]
impl GitFetcher for MainGitFetcher {
    async fn get_latest_hash(
        &self,
        repo_url: &str,
        branch: &str,
    ) -> Result<CommitHash, CommitHashError> {
        tokio::process::Command::new("git")
            .args(["ls-remote", "--", repo_url, branch])
            .output()
            .await
            .map_err(CommitHashError::from)
            .and_then(handle_git_output_result)
            .and_then(|stdout| extract_hash(stdout, repo_url.to_string(), branch.to_string()))
    }
}

/// Analyzes the `git` exit status to handle process output.
fn handle_git_output_result(output: std::process::Output) -> Result<Vec<u8>, CommitHashError> {
    if output.status.success() {
        Ok(output.stdout)
    } else {
        let stderr = String::from_utf8_lossy(&output.stderr).into_owned();
        Err(CommitHashError::UnexpectedStatus(stderr))
    }
}

/// Extracts the commit hash from a `git ls-remote` process stdout.
fn extract_hash(
    stdout: Vec<u8>,
    repo_url: String,
    branch: String,
) -> Result<CommitHash, CommitHashError> {
    let hash_str = String::from_utf8_lossy(&stdout)
        .split_whitespace()
        .next()
        .map(|s| s.to_string())
        .ok_or(CommitHashError::UnexpectedOutput {
            stdout: String::from_utf8_lossy(&stdout).into_owned(),
            repo_url,
            branch,
        })?;

    Ok(CommitHash::new(hash_str)?)
}

#[cfg(test)]
mod tests {
    #![allow(
        clippy::panic,
        clippy::expect_used,
        clippy::todo,
        clippy::unimplemented,
        clippy::indexing_slicing
    )]

    use super::*;

    #[test]
    fn test_extract_hash_success() {
        let stdout = b"678c4343237127dbadbf1806dd98b2154ffd2ebe\trefs/heads/main\n".to_vec();
        let repo_url = "https://github.com/Nilirad/commit-bridge".to_string();
        let branch = "main".to_string();

        let result = extract_hash(stdout, repo_url, branch);
        assert!(result.is_ok());
        assert_eq!(
            result.unwrap().as_str(),
            "678c4343237127dbadbf1806dd98b2154ffd2ebe"
        );
    }

    #[test]
    fn test_extract_hash_empty_output() {
        let stdout = b"".to_vec();
        let repo_url = "https://github.com/Nilirad/commit-bridge".to_string();
        let branch = "main".to_string();

        let result = extract_hash(stdout.clone(), repo_url.clone(), branch.clone());

        let Err(CommitHashError::UnexpectedOutput {
            stdout: err_stdout,
            repo_url: err_repo_url,
            branch: err_branch,
        }) = result
        else {
            panic!("Expected UnexpectedOutput error");
        };

        assert_eq!(err_stdout, String::from_utf8(stdout).unwrap_or_default());
        assert_eq!(err_repo_url, repo_url);
        assert_eq!(err_branch, branch);
    }

    #[test]
    fn test_extract_hash_whitespace_only() {
        let stdout = b"   \n\t ".to_vec();
        let repo_url = "https://github.com/Nilirad/commit-bridge".to_string();
        let branch = "main".to_string();

        let result = extract_hash(stdout.clone(), repo_url.clone(), branch.clone());

        let Err(CommitHashError::UnexpectedOutput {
            stdout: err_stdout,
            repo_url: err_repo_url,
            branch: err_branch,
        }) = result
        else {
            panic!("Expected UnexpectedOutput error");
        };

        assert_eq!(err_stdout, String::from_utf8(stdout).unwrap_or_default());
        assert_eq!(err_repo_url, repo_url);
        assert_eq!(err_branch, branch);
    }
}