//! chrs-code-edit: Autonomous Git-based code editing for CHORUS.

use git2::{Repository, BranchType};
use std::path::Path;
use thiserror::Error;

#[derive(Debug, Error)]
pub enum EditError {
    #[error("Git error: {0}")]
    Git(#[from] git2::Error),
    #[error("IO error: {0}")]
    Io(#[from] std::io::Error),
}

/// Manages isolated Git worktrees/branches for agent tasks.
pub struct WorktreeManager {
    repo: Repository,
}

impl WorktreeManager {
    /// Open an existing repository.
    pub fn open<P: AsRef<Path>>(path: P) -> Result<Self, EditError> {
        let repo = Repository::open(path)?;
        Ok(Self { repo })
    }

    /// Create a new branch for a specific task.
    /// 
    /// **Why**: Isolation ensures that agents do not conflict with each other 
    /// or the main branch while performing autonomous edits.
    pub fn spawn_task_branch(&self, task_id: &str) -> Result<String, EditError> {
        let branch_name = format!("task/{}", task_id);
        let head = self.repo.head()?.peel_to_commit()?;
        self.repo.branch(&branch_name, &head, false)?;
        println!("[CODE-EDIT] Spawned branch: {}", branch_name);
        Ok(branch_name)
    }

    /// Checkout a specific branch.
    pub fn checkout_branch(&self, branch_name: &str) -> Result<(), EditError> {
        let obj = self.repo.revparse_single(&format!("refs/heads/{}", branch_name))?;
        self.repo.checkout_tree(&obj, None)?;
        self.repo.set_head(&format!("refs/heads/{}", branch_name))?;
        Ok(())
    }
}