use anyhow::Result;

use crate::git;

use super::helpers::require_session;

pub async fn action(branch: &str) -> Result<()> {
    let (_, session) = require_session(branch).await;

    // Check for uncommitted changes (staged + unstaged)
    let status = tokio::process::Command::new("git")
        .args(["-C", &session.worktree, "status", "--porcelain"])
        .stdout(std::process::Stdio::piped())
        .stderr(std::process::Stdio::piped())
        .output()
        .await;

    let status = match status {
        Ok(o) if o.status.success() => String::from_utf8_lossy(&o.stdout).to_string(),
        _ => {
            eprintln!("\u{2716} git status failed");
            std::process::exit(1);
        }
    };

    let args: Vec<String> = if !status.trim().is_empty() {
        // Show uncommitted changes
        let has_head = tokio::process::Command::new("git")
            .args(["-C", &session.worktree, "rev-parse", "--verify", "HEAD"])
            .stdout(std::process::Stdio::null())
            .stderr(std::process::Stdio::null())
            .status()
            .await;
        if has_head.is_ok_and(|s| s.success()) {
            vec!["diff".into(), "HEAD".into()]
        } else {
            vec!["diff".into()]
        }
    } else {
        // No uncommitted changes — show full branch diff vs main
        let main = git::main_branch(Some(&session.worktree)).await?;
        vec!["diff".into(), format!("{main}...{branch}")]
    };

    // Run git diff with inherited stdio
    let status = std::process::Command::new("git")
        .args(
            std::iter::once("-C".to_string())
                .chain(std::iter::once(session.worktree.clone()))
                .chain(args),
        )
        .stdin(std::process::Stdio::inherit())
        .stdout(std::process::Stdio::inherit())
        .stderr(std::process::Stdio::inherit())
        .spawn()?
        .wait()?;

    if !status.success() {
        std::process::exit(status.code().unwrap_or(1));
    }

    Ok(())
}