stax 0.56.0

//! `stax create` — create a new branch, optionally with a first commit.
//!
//! Two flows live in this file:
//!
//! - **Commit-first** (the default when `-m "msg"` is used and the new branch
//!   stacks on the current branch): `git commit` runs on the current branch
//!   *before* any stax ref is created. On hook failure or Ctrl+C nothing is
//!   touched — no orphan branch, no `mybranch-2` drift on retry. The new
//!   commit is then split off to the new branch and the current branch ref is
//!   moved back to its pre-commit SHA.
//! - **Branch-first** (everything else: name-only `st create`, `--from
//!   <other>`, no-op `-m` with a clean tree): create the branch and switch to
//!   it first, then optionally commit. Failures here use the legacy
//!   `rollback_create` cleanup.
//!
//! Both flows share `create_branch_with_banner` for the create → metadata →
//! `--insert` → checkout → summary sequence.
//!
//! When the user passes `-m` but nothing is staged and `-a` wasn't supplied,
//! `stax create` offers the shared staging menu (see
//! `crate::commands::staging`) — stage all, `--patch`, empty branch, or abort.

use crate::commands::staging::{self, ContinueLabel, StagingAction};
use crate::config::Config;
use crate::engine::{BranchMetadata, Stack};
use crate::git::GitRepo;
use crate::remote;
use anyhow::{bail, Context, Result};
use colored::Colorize;
use console::Term;
use dialoguer::{theme::ColorfulTheme, Input, Select};
use std::path::Path;
use std::process::Command;

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
enum StageMode {
    /// No staging (plain `stax create <name>` or wizard empty-branch choice).
    None,
    /// `-m` was passed without `-a`: prompt if nothing is staged, otherwise
    /// commit what's already in the index.
    ExistingOnly,
    /// `-a/--all` was passed: force-stage everything.
    All,
}

pub fn run(
    name: Option<String>,
    message: Option<String>,
    from: Option<String>,
    prefix: Option<String>,
    all: bool,
    insert: bool,
) -> Result<()> {
    let repo = GitRepo::open()?;
    let config = Config::load()?;
    let current = repo.current_branch()?;
    let parent_branch = from.unwrap_or_else(|| current.clone());
    let generated_from_message = name.is_none() && message.is_some();

    if repo.branch_commit(&parent_branch).is_err() {
        anyhow::bail!("Branch '{}' does not exist", parent_branch);
    }

    // Get the branch name from either name or message
    // When using -m, the message is used for both branch name and commit message.
    // `stax create -m` respects already-staged changes. When nothing is staged
    // it offers an interactive menu (or bails in non-TTY). Use -a/--all to
    // skip the menu and force-stage.
    // When neither name nor message is provided, launch interactive wizard.
    let (input, commit_message, stage_mode) = match (&name, &message) {
        (Some(n), _) => (
            n.clone(),
            None,
            if all { StageMode::All } else { StageMode::None },
        ),
        (None, Some(m)) => (
            m.clone(),
            Some(m.clone()),
            if all {
                StageMode::All
            } else {
                StageMode::ExistingOnly
            },
        ),
        (None, None) => {
            if !Term::stderr().is_term() {
                bail!(
                    "Branch name required. Use: stax create <name> or stax create -m \"message\""
                );
            }
            // Launch interactive wizard
            let (wizard_name, wizard_msg, wizard_stage) =
                run_wizard(repo.workdir()?, &parent_branch)?;
            (wizard_name, wizard_msg, wizard_stage)
        }
    };

    // Format the branch name according to config
    let branch_name = match prefix.as_deref() {
        Some(_) => config.format_branch_name_with_prefix_override(&input, prefix.as_deref()),
        None => config.format_branch_name(&input),
    };
    let existing_branches = repo.list_branches()?;
    let branch_name =
        resolve_branch_name_conflicts(&branch_name, &existing_branches, generated_from_message)?;

    // Before creating the branch, resolve the staging question. Doing this
    // early means declining ("Abort" / empty `--patch` exit) is a clean no-op
    // — no orphaned branch, no refs touched.
    //
    // Returns (needs_stage_all, skip_commit):
    //   needs_stage_all — run `git add -A` before the commit.
    //   skip_commit     — the user picked "empty branch"; drop the message and
    //                     create an empty branch instead of committing.
    let (needs_stage_all, skip_commit) = if stage_mode == StageMode::ExistingOnly {
        let workdir = repo.workdir()?;
        if staging::is_staging_area_empty(workdir)? && staging::has_uncommitted_changes(workdir) {
            match staging::prompt_action(
                workdir,
                ContinueLabel::EmptyBranch,
                "Stage files with `git add` first, or use `stax create -a -m \"message\"`.",
            )? {
                StagingAction::All => (true, false),
                StagingAction::Patch => {
                    staging::stage_patch(workdir)?;
                    if staging::is_staging_area_empty(workdir)? {
                        staging::print_patch_empty_notice();
                        return Ok(());
                    }
                    (false, false)
                }
                StagingAction::Continue => (false, true),
                StagingAction::Abort => {
                    println!(
                        "{}",
                        "Aborted. Stage files with `git add` first, or use `stax create -a -m \"message\"`."
                            .dimmed()
                    );
                    return Ok(());
                }
            }
        } else {
            (false, false)
        }
    } else {
        (false, false)
    };

    let commit_message = if skip_commit { None } else { commit_message };

    // Commit-first path: when the user supplied -m and the new branch stacks on
    // the current branch, run the commit on the current branch BEFORE creating
    // or switching to the new branch. If pre-commit hooks fail (or the user
    // hits Ctrl+C) we exit with no refs touched: no orphan branch, no name
    // drift to `-2`/`-3`, and the user stays on their original branch with
    // their working tree preserved. Only on a successful commit do we split
    // it off to the new branch and move the parent ref back.
    if let Some(msg) = commit_message.as_deref() {
        if parent_branch == current {
            return run_commit_first(
                &repo,
                &config,
                &current,
                &branch_name,
                msg,
                stage_mode,
                needs_stage_all,
                insert,
            );
        }
    }

    create_branch_with_banner(
        &repo,
        &config,
        &current,
        &parent_branch,
        &branch_name,
        insert,
    )?;

    // Stage/commit behavior:
    // - StageMode::All / needs_stage_all => run `git add -A`
    // - StageMode::ExistingOnly (files already staged) => keep current index
    // - StageMode::None => no staging/committing
    if stage_mode != StageMode::None {
        let workdir = repo.workdir()?;

        if stage_mode == StageMode::All || needs_stage_all {
            if let Err(e) = staging::stage_all(workdir) {
                rollback_create(&repo, &current, &branch_name);
                return Err(e);
            }
        }

        // Only commit if -m was provided. This block only runs for the
        // `--from <other>` + `-m` path; the common `-m` without `--from` case
        // returns early via `run_commit_first`.
        if let Some(msg) = commit_message {
            if staging::is_staging_area_empty(workdir)? {
                println!("{}", "No changes to commit".dimmed());
            } else {
                commit_or_rollback(workdir, &msg, &repo, &current, &branch_name)?;
                println!("Committed: {}", msg.cyan());
            }
        } else if stage_mode == StageMode::All {
            println!("{}", "Changes staged".dimmed());
        }
    }

    if config.ui.tips {
        println!(
            "{}",
            "Hint: Run `st ss` to submit, or add changes with `st modify -a -m \"message\"`"
                .dimmed()
        );
    }

    Ok(())
}

/// Run `git commit -m <msg>` on the currently checked-out branch. On any
/// failure (spawn error, non-zero exit, hook rejection), invoke
/// `rollback_create` to clean up the partially-created branch before
/// returning the error. Used only by the branch-first path — commit-first
/// runs its own bare `git commit` because there's nothing to roll back yet.
fn commit_or_rollback(
    workdir: &Path,
    message: &str,
    repo: &GitRepo,
    original: &str,
    new_branch: &str,
) -> Result<()> {
    let status = Command::new("git")
        .args(["commit", "-m", message])
        .current_dir(workdir)
        .status();
    match status {
        Ok(s) if s.success() => Ok(()),
        Ok(_) => {
            rollback_create(repo, original, new_branch);
            bail!(
                "Commit failed (pre-commit hook or other error). \
                 Branch rolled back. Fix the issue and retry."
            );
        }
        Err(e) => {
            rollback_create(repo, original, new_branch);
            Err(anyhow::Error::from(e).context("Failed to run git commit"))
        }
    }
}

/// Best-effort rollback: unstage changes, checkout the original branch,
/// delete the new branch and its metadata.
/// Errors during rollback are intentionally ignored (matching the pattern in split_hunk/app.rs).
fn rollback_create(repo: &GitRepo, original_branch: &str, new_branch: &str) {
    if let Ok(workdir) = repo.workdir() {
        // Reset index first so staged changes from stage_all don't block checkout
        // or leak onto the original branch. This preserves working tree files.
        let _ = Command::new("git")
            .args(["reset"])
            .current_dir(workdir)
            .status();
        let _ = Command::new("git")
            .args(["checkout", original_branch])
            .current_dir(workdir)
            .status();
    }
    let _ = repo.delete_branch(new_branch, true);
    let _ = BranchMetadata::delete(repo.inner(), new_branch);
}

/// Graphite-style commit-first flow: commit on the current branch, then split
/// the new commit off to a new branch and move the current branch ref back.
///
/// The key property: nothing observable changes until `git commit` returns
/// successfully. If pre-commit hooks reject the commit, or the user hits
/// Ctrl+C during the commit, no branch is created, no metadata is written,
/// and HEAD is untouched — so retrying the exact same command is a clean
/// operation that does not drift into `mybranch-2`, `mybranch-3`, etc.
///
/// Precondition: `parent_branch == current` (i.e. no explicit `--from`).
#[allow(clippy::too_many_arguments)]
fn run_commit_first(
    repo: &GitRepo,
    config: &Config,
    current: &str,
    branch_name: &str,
    message: &str,
    stage_mode: StageMode,
    needs_stage_all: bool,
    insert: bool,
) -> Result<()> {
    let workdir = repo.workdir()?;

    // Stage (if requested) BEFORE the commit so hooks see the final tree.
    if stage_mode == StageMode::All || needs_stage_all {
        staging::stage_all(workdir)?;
    }

    // If nothing is staged by the time we reach here, there is no commit to
    // make. Fall back to creating an empty branch — same shape as the
    // branch-first path without the trailing commit.
    if staging::is_staging_area_empty(workdir)? {
        create_branch_with_banner(repo, config, current, current, branch_name, insert)?;
        println!("{}", "No changes to commit".dimmed());
        print_tips(config);
        return Ok(());
    }

    // Capture the pre-commit SHA so we can move the current branch back to it
    // after splitting the new commit off.
    let old_parent_sha = repo.branch_commit(current)?;

    // Run the commit on the current branch. `--quiet` suppresses git's
    // "[<branch> <sha>] <msg>" summary that would otherwise show the commit
    // landing on the original branch — we move it off a few calls later and
    // print our own summary. Pre-commit hook output is not suppressed by -q.
    let commit_status = Command::new("git")
        .args(["commit", "--quiet", "-m", message])
        .current_dir(workdir)
        .status()
        .context("Failed to run git commit")?;

    if !commit_status.success() {
        bail!(
            "Commit failed (pre-commit hook or other error). \
             No branch was created — fix the issue and retry with the same command."
        );
    }

    // From here on the commit exists on the current branch. Any failure must
    // undo the commit with a soft reset so the user's working tree and staged
    // changes are preserved.
    let new_sha = repo.branch_commit(current)?;

    if let Err(e) = repo.create_branch_at_commit(branch_name, &new_sha) {
        rollback_after_commit(workdir, &old_parent_sha, None, repo);
        return Err(e);
    }

    let meta = BranchMetadata::new(current, &old_parent_sha);
    if let Err(e) = meta.write(repo.inner(), branch_name) {
        rollback_after_commit(workdir, &old_parent_sha, Some(branch_name), repo);
        return Err(e);
    }

    if insert {
        if let Err(e) = apply_insert_reparenting(repo, current, branch_name) {
            rollback_after_commit(workdir, &old_parent_sha, Some(branch_name), repo);
            return Err(e);
        }
    }

    // Move the current branch ref back to the pre-commit SHA. The new commit
    // now lives only on `branch_name`.
    let current_ref = format!("refs/heads/{}", current);
    if let Err(e) = repo.update_ref(&current_ref, &old_parent_sha) {
        rollback_after_commit(workdir, &old_parent_sha, Some(branch_name), repo);
        return Err(e);
    }

    // Switch to the new branch. HEAD still points at `current` (now at the old
    // SHA) while the working tree matches the new commit; `git checkout` moves
    // HEAD without touching the working tree since it's already correct. If
    // this fails there's nothing to undo — the commit lives on the new branch,
    // `current` is reset — the user just needs `git checkout <new>` manually.
    repo.checkout(branch_name)?;

    print_remote_parent_warning(repo, config, current);
    println!(
        "Created and switched to branch '{}' (stacked on {})",
        branch_name.green(),
        current.blue()
    );
    println!("Committed: {}", message.cyan());
    print_tips(config);

    Ok(())
}

/// Undo the partial state left by `run_commit_first` when a step after
/// `git commit` (branch creation, metadata write, ref update) fails.
///
/// `--soft` keeps the working tree and index exactly as git left them after
/// the successful commit, so the user can retry without re-staging.
fn rollback_after_commit(workdir: &Path, old_sha: &str, new_branch: Option<&str>, repo: &GitRepo) {
    if let Some(name) = new_branch {
        let _ = BranchMetadata::delete(repo.inner(), name);
        let _ = repo.delete_branch(name, true);
    }
    let _ = Command::new("git")
        .args(["reset", "--soft", old_sha])
        .current_dir(workdir)
        .status();
}

/// Create `branch_name` stacked on `parent_branch`, write stax metadata,
/// apply `--insert` reparenting, check out the new branch, and print the
/// "Created and switched…" banner. On any failure, undo all of it with
/// `rollback_create` so the caller sees a clean failure.
///
/// `original` is the branch the user was on when `st create` was invoked; it's
/// where `rollback_create` checks out on failure. For the commit-first
/// no-changes fallback `original == parent_branch == current`; for the
/// branch-first flow `original == current`, and `parent_branch` may or may not
/// equal it (the `--from` case).
///
/// The caller owns whatever comes next — the trailing "No changes to commit"
/// note, the stage/commit block, or the tips line.
fn create_branch_with_banner(
    repo: &GitRepo,
    config: &Config,
    original: &str,
    parent_branch: &str,
    branch_name: &str,
    insert: bool,
) -> Result<()> {
    if parent_branch == original {
        repo.create_branch(branch_name)?;
    } else {
        repo.create_branch_at(branch_name, parent_branch)?;
    }

    let parent_rev = repo.branch_commit(parent_branch)?;
    let meta = BranchMetadata::new(parent_branch, &parent_rev);
    if let Err(e) = meta.write(repo.inner(), branch_name) {
        rollback_create(repo, original, branch_name);
        return Err(e);
    }

    if insert {
        if let Err(e) = apply_insert_reparenting(repo, parent_branch, branch_name) {
            rollback_create(repo, original, branch_name);
            return Err(e);
        }
    }

    if let Err(e) = repo.checkout(branch_name) {
        rollback_create(repo, original, branch_name);
        return Err(e);
    }

    print_remote_parent_warning(repo, config, parent_branch);
    println!(
        "Created and switched to branch '{}' (stacked on {})",
        branch_name.green(),
        parent_branch.blue()
    );

    Ok(())
}

/// Reparent children of `parent_branch` onto `new_branch` and print the usual
/// `--insert` summary. Extracted from the branch-first path so both flows
/// share the same behaviour.
fn apply_insert_reparenting(repo: &GitRepo, parent_branch: &str, new_branch: &str) -> Result<()> {
    let stack = Stack::load(repo)?;
    let Some(parent_info) = stack.branches.get(parent_branch) else {
        return Ok(());
    };
    let children: Vec<String> = parent_info
        .children
        .iter()
        .filter(|c| c.as_str() != new_branch)
        .cloned()
        .collect();

    if children.is_empty() {
        return Ok(());
    }

    let new_parent_rev = repo.branch_commit(new_branch)?;
    for child in &children {
        if let Some(child_meta) = BranchMetadata::read(repo.inner(), child)? {
            let updated = BranchMetadata {
                parent_branch_name: new_branch.to_string(),
                parent_branch_revision: new_parent_rev.clone(),
                ..child_meta
            };
            updated.write(repo.inner(), child)?;
        }
    }

    println!(
        "Reparented {} child branch(es) to '{}'",
        children.len(),
        new_branch.green()
    );
    for child in &children {
        println!("  {} -> {}", child.cyan(), new_branch.green());
    }
    println!(
        "{}",
        "Run `stax restack --all` to rebase the reparented branches.".yellow()
    );

    Ok(())
}

fn print_remote_parent_warning(repo: &GitRepo, config: &Config, parent_branch: &str) {
    let Ok(workdir) = repo.workdir() else {
        return;
    };
    if let Ok(remote_branches) = remote::get_remote_branches(workdir, config.remote_name()) {
        if !remote_branches.contains(&parent_branch.to_string()) {
            println!(
                "{}",
                format!(
                    "Warning: parent '{}' is not on remote '{}'.",
                    parent_branch,
                    config.remote_name()
                )
                .yellow()
            );
        }
    }
}

fn print_tips(config: &Config) {
    if config.ui.tips {
        println!(
            "{}",
            "Hint: Run `st ss` to submit, or add changes with `st modify -a -m \"message\"`"
                .dimmed()
        );
    }
}

#[derive(Clone, Copy)]
enum BranchNameConflict<'a> {
    Exact(&'a str),
    ExistingIsAncestor(&'a str),
    ExistingIsDescendant(&'a str),
}

fn resolve_branch_name_conflicts(
    branch_name: &str,
    existing_branches: &[String],
    generated_from_message: bool,
) -> Result<String> {
    match detect_branch_name_conflict(branch_name, existing_branches) {
        None => Ok(branch_name.to_string()),
        Some(BranchNameConflict::Exact(_) | BranchNameConflict::ExistingIsDescendant(_))
            if generated_from_message =>
        {
            for suffix in 2..1000 {
                let candidate = append_branch_suffix(branch_name, suffix);
                if detect_branch_name_conflict(&candidate, existing_branches).is_none() {
                    return Ok(candidate);
                }
            }

            bail!(
                "Cannot create a unique branch name from '{}'. Too many similarly named branches already exist.",
                branch_name
            );
        }
        Some(conflict) => bail!("{}", branch_name_conflict_message(branch_name, conflict)),
    }
}

fn detect_branch_name_conflict<'a>(
    branch_name: &str,
    existing_branches: &'a [String],
) -> Option<BranchNameConflict<'a>> {
    for existing in existing_branches {
        if branch_name == existing {
            return Some(BranchNameConflict::Exact(existing));
        }

        if branch_name.starts_with(&format!("{}/", existing)) {
            return Some(BranchNameConflict::ExistingIsAncestor(existing));
        }

        if existing.starts_with(&format!("{}/", branch_name)) {
            return Some(BranchNameConflict::ExistingIsDescendant(existing));
        }
    }

    None
}

fn branch_name_conflict_message(branch_name: &str, conflict: BranchNameConflict<'_>) -> String {
    match conflict {
        BranchNameConflict::Exact(existing) => format!(
            "Cannot create '{}': branch '{}' already exists.\n\
             Use `st checkout {}` or choose a different name.",
            branch_name, existing, existing
        ),
        BranchNameConflict::ExistingIsAncestor(existing) => format!(
            "Cannot create '{}': branch '{}' already exists.\n\
             Git doesn't allow a branch and its sub-path to coexist.\n\
             Either delete '{}' first, or use a different name like '{}-ui'.",
            branch_name, existing, existing, existing
        ),
        BranchNameConflict::ExistingIsDescendant(existing) => format!(
            "Cannot create '{}': branch '{}' already exists.\n\
             Git doesn't allow a branch and its sub-path to coexist.\n\
             Either delete '{}' first, or use a different name.",
            branch_name, existing, existing
        ),
    }
}

fn append_branch_suffix(branch_name: &str, suffix: usize) -> String {
    match branch_name.rsplit_once('/') {
        Some((prefix, leaf)) => format!("{}/{}-{}", prefix, leaf, suffix),
        None => format!("{}-{}", branch_name, suffix),
    }
}

/// Interactive wizard for branch creation when no arguments provided.
///
/// Returns `(branch_name, commit_message, stage_mode)`. When the wizard
/// routes to the staging menu and the user picks `--patch`, we run
/// `git add -p` inline so the caller sees the "staged manually" shape
/// (`StageMode::ExistingOnly`, no auto-stage-all).
fn run_wizard(
    workdir: &Path,
    parent_branch: &str,
) -> Result<(String, Option<String>, StageMode)> {
    println!();
    println!("╭─ Create Stacked Branch ─────────────────────────────╮");
    println!(
        "│ Parent: {:<43} │",
        format!("{} (current branch)", parent_branch.cyan())
    );
    println!("╰─────────────────────────────────────────────────────╯");
    println!();

    let name: String = Input::with_theme(&ColorfulTheme::default())
        .with_prompt("Branch name")
        .interact_text()?;

    if name.trim().is_empty() {
        bail!("Branch name cannot be empty");
    }

    let has_changes = staging::has_uncommitted_changes(workdir);
    let change_count = staging::count_uncommitted_changes(workdir);

    if !has_changes {
        println!();
        return Ok((name, None, StageMode::None));
    }

    println!();

    let stage_label = if change_count > 0 {
        format!("Stage all changes ({} files modified)", change_count)
    } else {
        "Stage all changes".to_string()
    };
    let options = vec![
        stage_label.as_str(),
        "Select changes to commit (--patch)",
        "Empty branch (no changes)",
    ];

    let choice = Select::with_theme(&ColorfulTheme::default())
        .with_prompt("What to include")
        .items(&options)
        .default(0)
        .interact()?;

    let stage_mode = match choice {
        0 => StageMode::All,
        1 => {
            staging::stage_patch(workdir)?;
            if staging::is_staging_area_empty(workdir)? {
                staging::print_patch_empty_notice();
                // Fall through to creating the branch with no commit —
                // matches the "empty branch" outcome.
                StageMode::None
            } else {
                StageMode::ExistingOnly
            }
        }
        _ => StageMode::None,
    };

    // Commit message only when we have something staged.
    let msg = if stage_mode != StageMode::None {
        println!();
        let m: String = Input::with_theme(&ColorfulTheme::default())
            .with_prompt("Commit message (Enter to skip)")
            .allow_empty(true)
            .interact_text()?;
        if m.is_empty() {
            None
        } else {
            Some(m)
        }
    } else {
        None
    };

    println!();
    Ok((name, msg, stage_mode))
}