worktree

#!/usr/bin/env bash
set -euo pipefail

usage() {
    cat <<'EOF'
Usage: ./worktree <mode> [options]

Checks whether this checkout contains the latest origin/main, or safely
fast-forwards a checkout that is directly behind it. Also removes build
caches when a worktree is deleted.

Modes:
  --check-main   Fetch origin/main and warn when HEAD does not contain it.
                 Never changes HEAD or the working tree; a fetch failure warns
                 without blocking worktree setup.
  --update-main  Fetch origin/main and fast-forward only when HEAD is its
                 ancestor. Refuses divergent history.
  --cleanup      Remove this checkout's Xcode DerivedData and simulator.
  --prune-derived-data
                 Remove DerivedData for deleted Codex worktrees of this repo,
                 including the older ~/.codex-workspaces/worktrees location.

Cleanup options:
  --dry-run      Report the cleanup actions without changing anything.
  --derived-data-root PATH
                 Inspect this directory instead of Xcode's default DerivedData.

Other options:
  -h, --help     Show this help.

Ownership comes from info.plist, never from the cache directory name alone.
Caches without ownership metadata and shared Xcode caches are retained.
EOF
}

if [ "$#" -eq 0 ]; then
    usage >&2
    exit 1
fi

mode="$1"
shift
dry_run=false
cleanup_args=("$mode")
case "$mode" in
    --cleanup|--prune-derived-data)
        while [ "$#" -gt 0 ]; do
            case "$1" in
                --dry-run) dry_run=true; cleanup_args+=(--dry-run); shift ;;
                --derived-data-root)
                    if [ "$#" -lt 2 ] || [ -z "$2" ] || [[ "$2" == --* ]]; then
                        echo "error: --derived-data-root requires a path" >&2
                        exit 1
                    fi
                    case "$2" in
                        /*|\~*) cleanup_args+=(--derived-data-root "$2") ;;
                        *) cleanup_args+=(--derived-data-root "$PWD/$2") ;;
                    esac
                    shift 2
                    ;;
                *) echo "error: unknown cleanup option '$1'" >&2; exit 1 ;;
            esac
        done
        ;;
    *)
        if [ "$#" -ne 0 ]; then
            usage >&2
            exit 1
        fi
        ;;
esac
main_ref="refs/remotes/origin/main"

fetch_main() {
    git fetch --quiet origin '+refs/heads/main:refs/remotes/origin/main'
}

short_commit() {
    git rev-parse --short=8 "$1"
}

case "$mode" in
    --cleanup|--prune-derived-data)
        # Resolve resources from the wrapper, even when invoked outside the checkout.
        cd "$(dirname "$0")"
        status=0
        python3 -B -m Tools.worktree_cleanup "${cleanup_args[@]}" || status=$?
        if [ "$mode" = --cleanup ]; then
            if [ "$dry_run" = true ]; then
                echo "Would run ./simulator --delete in $(pwd -P)" >&2
            else
                ./simulator --delete || status=$?
            fi
        fi
        exit "$status"
        ;;
    --check-main)
        if ! fetch_main; then
            echo "warning: could not fetch origin/main; main freshness is unknown" >&2
            exit 0
        fi

        if git merge-base --is-ancestor "$main_ref" HEAD; then
            echo "==> Checkout contains latest origin/main ($(short_commit "$main_ref"))"
        else
            echo "warning: checkout $(short_commit HEAD) does not contain latest origin/main ($(short_commit "$main_ref"))" >&2
            echo "warning: run the 'Update to latest main' action if this checkout should be a current main checkout" >&2
        fi
        ;;
    --update-main)
        echo "==> Fetching origin/main"
        fetch_main

        if git merge-base --is-ancestor "$main_ref" HEAD; then
            echo "==> Checkout already contains latest origin/main ($(short_commit "$main_ref"))"
            exit 0
        fi

        if ! git merge-base --is-ancestor HEAD "$main_ref"; then
            echo "error: checkout $(short_commit HEAD) has diverged from origin/main ($(short_commit "$main_ref")); refusing to rewrite or merge feature history" >&2
            echo "error: merge or rebase origin/main explicitly instead" >&2
            exit 1
        fi

        git merge --ff-only "$main_ref"
        echo "==> Fast-forwarded checkout to latest origin/main ($(short_commit HEAD))"
        ;;
    -h|--help)
        usage
        ;;
    *)
        echo "error: unknown option '$mode'" >&2
        usage >&2
        exit 1
        ;;
esac