#!/usr/bin/env bash
# Resolve and ensure the working-tree directory SDD uses for one plan's
# short-lived artifacts: task briefs, implementer reports, review packages,
# and the progress ledger. Print the plan directory's absolute path.
#
# One directory per plan (.superpowers/sdd/<plan-basename>/) so a follow-up
# plan in the same working tree can never read or overwrite another plan's
# artifacts. A stale ledger misread as current progress makes controllers
# skip whole task sequences — plan-scoping removes that failure structurally.
#
# Basename slugs collide when two plans share a filename (docs/alpha/plan.md
# vs docs/beta/plan.md), so each workspace records its owning plan's path in
# a plan-path marker (repo-relative in-repo, absolute outside). A workspace
# owned by a different plan is skipped and the slug disambiguated with the
# plan's parent-directory name, then a counter. A workspace with no marker
# predates the marker scheme and is adopted for the current plan so in-flight
# workspaces keep resolving — which means the first collision on such a
# legacy workspace adopts instead of detecting; acceptable, marker-less
# workspaces age out as plans finish.
#
# The workspace lives in the working tree (not under .git/) because Claude Code
# treats .git/ as a protected path and denies agent writes there — which blocks
# an implementer subagent from writing its report file. A self-ignoring
# .gitignore at .superpowers/sdd/ keeps every plan's workspace out of
# `git status` and out of accidental commits without modifying any tracked file.
#
# Single source of truth for the workspace location, so task-brief and
# review-package cannot drift to different directories.
#
# Usage: sdd-workspace PLAN_FILE
set -euo pipefail

if [ $# -ne 1 ]; then
  echo "usage: sdd-workspace PLAN_FILE" >&2
  exit 2
fi

plan=$1
[ -f "$plan" ] || { echo "no such plan file: $plan" >&2; exit 2; }

slug=$(basename "$plan" .md)
[ -n "$slug" ] && [ "$slug" != "." ] && [ "$slug" != ".." ] \
  || { echo "cannot derive a workspace name from: $plan" >&2; exit 2; }

root=$(git rev-parse --show-toplevel)
base="$root/.superpowers/sdd"

# Normalize the plan path (physical directory, so relative/absolute/../
# spellings of one plan compare equal) and express it as the marker value:
# repo-relative when the plan lives under the repo root, absolute otherwise.
plan_dir=$(CDPATH= cd -- "$(dirname "$plan")" && pwd -P)
plan_abs="$plan_dir/$(basename "$plan")"
case "$plan_abs" in
  "$root"/*) plan_id=${plan_abs#"$root"/} ;;
  *)         plan_id=$plan_abs ;;
esac

# True when the workspace at $1 is (or becomes) this plan's: an existing
# marker must name this plan; a missing marker means a new workspace or a
# pre-marker legacy one, and either way the plan claims it by writing one.
owns() {
  if [ -e "$1/plan-path" ]; then
    [ "$(cat "$1/plan-path")" = "$plan_id" ]
  else
    mkdir -p "$1"
    printf '%s\n' "$plan_id" > "$1/plan-path"
  fi
}

dir="$base/$slug"
if ! owns "$dir"; then
  parent=$(basename "$plan_dir")
  dir="$base/$slug-$parent"
  if ! owns "$dir"; then
    n=2
    while ! owns "$base/$slug-$parent-$n"; do n=$((n + 1)); done
    dir="$base/$slug-$parent-$n"
  fi
fi

printf '*\n' > "$base/.gitignore"
CDPATH= cd -- "$dir" && pwd