use crate::bare::GitBare;
use crate::error::{GitError, GitResult};
use crate::pb::{CompareBranchRequest, CompareBranchResponse};

impl GitBare {
    pub fn compare_branch(
        &self,
        request: CompareBranchRequest,
    ) -> GitResult<CompareBranchResponse> {
        crate::sanitize::validate_ref_name(&request.source_branch)?;
        crate::sanitize::validate_ref_name(&request.target_branch)?;
        let repo = self.gix_repo()?;
        let source_ref = format!("refs/heads/{}", request.source_branch);
        let target_ref = format!("refs/heads/{}", request.target_branch);
        let source_id = repo.find_reference(source_ref.as_str())?.peel_to_id()?;
        let target_id = repo.find_reference(target_ref.as_str())?.peel_to_id()?;
        let source_hex = source_id.to_string();
        let target_hex = target_id.to_string();
        let merge_base = repo
            .merge_base(source_id.detach(), target_id.detach())
            .ok()
            .map(|id| self.oid_to_pb(id.to_string()));
        let result = duct::cmd(
            "git",
            [
                "--git-dir",
                self.bare_dir.to_string_lossy().as_ref(),
                "rev-list",
                "--left-right",
                "--count",
                &format!("{}...{}", source_hex, target_hex),
            ],
        )
        .stdout_capture()
        .stderr_capture()
        .unchecked()
        .run()?;
        if !result.status.success() {
            return Err(GitError::CommandFailed {
                status_code: result.status.code(),
                stderr: String::from_utf8_lossy(&result.stderr).into_owned(),
            });
        }
        let output = String::from_utf8_lossy(&result.stdout);
        let parts: Vec<&str> = output.split_whitespace().collect();
        let ahead_by = parts.first().and_then(|s| s.parse().ok()).unwrap_or(0);
        let behind_by = parts.get(1).and_then(|s| s.parse().ok()).unwrap_or(0);
        Ok(CompareBranchResponse {
            ahead: ahead_by > 0,
            behind: behind_by > 0,
            ahead_by,
            behind_by,
            merge_base,
        })
    }
}