heddle-cli 0.2.1

// SPDX-License-Identifier: Apache-2.0
//! Rebase command - replay commits onto another thread.

use std::fs;

use anyhow::{Result, anyhow};
use refs::Head;
use repo::Repository;

use super::{snapshot::ensure_current_state, worktree_safety::ensure_worktree_clean};
use crate::{
    cli::{Cli, should_output_json},
    config::UserConfig,
};

mod rebase_ops;
mod rebase_state;

use rebase_ops::{replay_commits, replay_commits_silent};
pub(crate) use rebase_state::load_rebase_state as load_persisted_rebase_state;
use rebase_state::{
    RebaseState, collect_commits_to_rebase, is_ancestor_of, load_rebase_state, save_rebase_state,
};

const REBASE_STATE_FILE: &str = "REBASE_STATE";

pub(crate) enum OperatorContinueStatus {
    Continued,
    Completed,
    Blocked,
}

pub fn cmd_rebase(
    cli: &Cli,
    thread: Option<&str>,
    abort: bool,
    cont: bool,
    force: bool,
) -> Result<()> {
    // Same metadata-resolution pattern as `cmd_merge`: open at CWD to
    // discover the active thread, then re-open at that thread's
    // metadata-recorded worktree so commits are replayed into the
    // thread's actual checkout. See `Repository::active_worktree_path`
    // for fallback semantics.
    let cwd_repo = Repository::open(cli.repo.as_ref().unwrap_or(&std::env::current_dir()?))?;
    let target_path = cwd_repo.active_worktree_path()?;
    let repo = if target_path == *cwd_repo.root() {
        cwd_repo
    } else {
        Repository::open(&target_path)?
    };

    // Rebase replays commits onto another thread by mutating the worktree
    // (fast-forward via `fast_forward_attached` flows through
    // `plan_worktree_apply`, which silently auto-falls back to
    // `FullRematerialize` on a dirty worktree — that wipes uncommitted
    // edits). The guard runs only on the entry path (not `--abort` /
    // `--continue`, which need access to the in-progress state on disk).
    if !force && !abort && !cont {
        ensure_worktree_clean(&repo, "rebase")?;
    }

    run_rebase(&repo, thread, abort, cont, Some(cli))
}

pub(crate) fn cmd_rebase_silent(
    repo: &Repository,
    thread: Option<&str>,
    abort: bool,
    cont: bool,
) -> Result<()> {
    run_rebase(repo, thread, abort, cont, None)
}

pub(crate) fn continue_rebase_for_operator(repo: &Repository) -> Result<OperatorContinueStatus> {
    let rebase_state_path = repo.heddle_dir().join(REBASE_STATE_FILE);
    if !rebase_state_path.exists() {
        return Err(anyhow!("No rebase in progress"));
    }

    let before = load_rebase_state(&rebase_state_path)?;
    if let Some(pre_conflict_head) = before.pre_conflict_head {
        let current_state = repo
            .current_state()?
            .ok_or_else(|| anyhow!("No current state"))?;
        if current_state.change_id != pre_conflict_head
            && Some(current_state.change_id) != before.pending_manual_resolution
        {
            let current_tree = repo
                .store()
                .get_tree(&current_state.tree)?
                .ok_or_else(|| anyhow!("Current state tree not found"))?;
            let worktree_status = repo.compare_worktree_cached(&current_tree)?;
            let worktree_is_clean = worktree_status.modified.is_empty()
                && worktree_status.added.is_empty()
                && worktree_status.deleted.is_empty();
            if !worktree_is_clean {
                return Ok(OperatorContinueStatus::Blocked);
            }
        }
    }
    let before_index = before.current_index;
    let before_pending_manual_resolution = before.pending_manual_resolution;

    cmd_rebase_silent(repo, None, false, true)?;

    if !rebase_state_path.exists() {
        return Ok(OperatorContinueStatus::Completed);
    }

    let after = load_rebase_state(&rebase_state_path)?;
    if after.pending_manual_resolution.is_some()
        && after.current_index == before_index
        && after.pending_manual_resolution == before_pending_manual_resolution
    {
        return Ok(OperatorContinueStatus::Blocked);
    }

    Ok(OperatorContinueStatus::Continued)
}

pub(crate) fn has_persisted_rebase_state(repo: &Repository) -> bool {
    repo.heddle_dir().join(REBASE_STATE_FILE).exists()
}

fn run_rebase(
    repo: &Repository,
    thread: Option<&str>,
    abort: bool,
    cont: bool,
    cli: Option<&Cli>,
) -> Result<()> {
    let rebase_state_path = repo.heddle_dir().join(REBASE_STATE_FILE);

    if abort {
        return handle_abort(repo, &rebase_state_path, cli);
    }

    if cont {
        return handle_continue(repo, &rebase_state_path, cli);
    }

    let target_thread = thread.ok_or_else(|| anyhow!("Usage: heddle rebase <thread>"))?;

    let current_change = ensure_current_state(
        repo,
        &UserConfig::load_default().unwrap_or_default(),
        Some(format!(
            "Bootstrap git-overlay before rebasing onto {}",
            target_thread
        )),
    )?;
    let current_state = repo
        .store()
        .get_state(&current_change)?
        .ok_or_else(|| anyhow!("Current state not found"))?;

    let target_change_id = repo
        .refs()
        .get_thread(target_thread)?
        .ok_or_else(|| anyhow!("Thread '{}' not found", target_thread))?;

    if current_state.change_id == target_change_id {
        if let Some(cli) = cli
            && should_output_json(cli, Some(repo.config()))
        {
            println!("{{\"status\": \"up_to_date\"}}");
        } else if cli.is_some() {
            println!("Already up to date");
        }
        return Ok(());
    }

    let is_ancestor = is_ancestor_of(repo, &current_state.change_id, &target_change_id)?;

    if is_ancestor {
        repo.fast_forward_attached(&target_change_id)?;

        if let Some(cli) = cli
            && should_output_json(cli, Some(repo.config()))
        {
            println!(
                "{{\"status\": \"fast_forwarded\", \"to\": \"{}\"}}",
                target_change_id
            );
        } else if cli.is_some() {
            // Lead with the active thread name (where applicable) so
            // operators don't need to map a worktree path back to a
            // thread mentally. JSON output is unchanged.
            match repo.head_ref()? {
                Head::Attached { thread } => {
                    println!("Fast-forwarded {} to {}", thread, target_change_id.short())
                }
                Head::Detached { .. } => {
                    println!("Fast-forwarded to {}", target_change_id.short())
                }
            }
        }
        return Ok(());
    }

    let commits_to_replay =
        collect_commits_to_rebase(repo, &current_state.change_id, &target_change_id)?;

    if commits_to_replay.is_empty() {
        repo.fast_forward_attached(&target_change_id)?;

        if let Some(cli) = cli
            && should_output_json(cli, Some(repo.config()))
        {
            println!("{{\"status\": \"up_to_date\"}}");
        } else if cli.is_some() {
            println!("Already up to date");
        }
        return Ok(());
    }

    let rebase_state = RebaseState {
        onto: target_change_id,
        commits_to_replay: commits_to_replay.clone(),
        current_index: 0,
        original_head: current_state.change_id,
        pending_manual_resolution: None,
        pre_conflict_head: None,
    };

    save_rebase_state(&rebase_state_path, &rebase_state)?;

    if let Some(cli) = cli
        && should_output_json(cli, Some(repo.config()))
    {
        println!(
            "{{\"status\": \"started\", \"commits\": {}}}",
            commits_to_replay.len()
        );
    } else if cli.is_some() {
        println!(
            "Rebasing {} commits onto {}",
            commits_to_replay.len(),
            target_change_id.short()
        );
    }

    if let Some(cli) = cli {
        replay_commits(repo, &rebase_state_path, cli)
    } else {
        replay_commits_silent(repo, &rebase_state_path)
    }
}

fn handle_abort(
    repo: &Repository,
    rebase_state_path: &std::path::Path,
    cli: Option<&Cli>,
) -> Result<()> {
    if !rebase_state_path.exists() {
        return Err(anyhow!("No rebase in progress"));
    }

    let state = load_rebase_state(rebase_state_path)?;
    repo.goto_without_record(&state.original_head)?;

    fs::remove_file(rebase_state_path)?;

    if let Some(cli) = cli
        && should_output_json(cli, Some(repo.config()))
    {
        println!("{{\"status\": \"aborted\"}}");
    } else if cli.is_some() {
        println!("Rebase aborted");
    }

    Ok(())
}

fn handle_continue(
    repo: &Repository,
    rebase_state_path: &std::path::Path,
    cli: Option<&Cli>,
) -> Result<()> {
    if !rebase_state_path.exists() {
        return Err(anyhow!("No rebase in progress"));
    }

    if let Some(cli) = cli {
        replay_commits(repo, rebase_state_path, cli)
    } else {
        replay_commits_silent(repo, rebase_state_path)
    }
}