#!/usr/bin/env bash
# gstack-capy-session — the full Capy skill wrapper: the checkout-owned half
# of a Capy session start. The frozen bootstrapper the Drive skill holds
# (capy/skill/gstack/scripts/install.sh) clones or fast-forwards this checkout
# and execs this script with its own arguments plus:
#   GSTACK_CAPY_WRAPPER_REV / GSTACK_CAPY_WRAPPER_PATH  the bootstrapper that ran
#   GSTACK_CAPY_REMOTE_MIN    the supported minimum from origin's capy/support.env, or `unknown`
#   GSTACK_CAPY_UPGRADED_FROM the version it fast-forwarded from (setup is never skipped then)
#   GSTACK_CAPY_LOCK_HELD=1   install mode: .gstack-capy-install.lock is held on an
#                             inherited descriptor; nothing here takes it again
# Because this file moves with the checkout, session-start behavior can change
# without anyone recopying the Drive skill; that includes the stale-copy owner
# action, read from capy/support.env through gstack_support_env_get.
#
# Always current when online: the bootstrapper moves a checkout only when it
# is below GSTACK_MIN_REVISION (the floor). Above the floor, this half keeps
# the checkout at the tip of origin's default branch: in install mode, when
# the bootstrapper's FETCH_HEAD is ahead of HEAD, it runs
# bin/gstack-upgrade --ff-only-no-reinstall (every refusal of gstack-upgrade
# applies: dirty, diverged, pinned, Bun hold, a live workflow lease) and on
# success re-execs the NEW checkout's copy of this script with the same
# arguments (GSTACK_CAPY_SELF_UPGRADED=1 stops a second attempt) before the
# installer runs. Lines: `SELF_UPGRADE: done <old> -> <new>` | `skipped (<reason>)`
# | `none (current)` | `disabled (<the variable: GSTACK_CAPY_SELF_UPGRADE=off or
# GSTACK_CAPY_AUTO_UPGRADE=0>)`.
# --check never moves the checkout; behind origin it prints
# `gstack-capy-session: behind origin/<branch>: <installed> -> <remote> (<n> commits); fix: ...`.
#
# Usage: gstack-capy-session [--check] --root <checkout> [gstack-capy-install arguments]
#   --check  certify only (bin/gstack-capy-install --check: the doctor with the
#            launch PATH and the remote minimum, the verdict, the launch line)
#   default  install or repair (bin/gstack-capy-install)
# The last line is the `gstack:` trailer; the exit status is the installer's.
set -u
ROOT="$(cd "$(dirname "$0")/.." && pwd -P)"
CHECK=0 SKILL=""
prev=""
for a in "$@"; do
  [ "$prev" = --root ] && ROOT="$a"
  case "$prev" in --for|--only) SKILL="$a" ;; esac
  [ "$a" = --check ] && CHECK=1
  prev="$a"
done
INSTALLER="$ROOT/bin/gstack-capy-install"
if [ ! -x "$INSTALLER" ]; then
  echo "gstack: fail installer — $INSTALLER is missing; fix: bash ${GSTACK_CAPY_WRAPPER_PATH:-<skill>/scripts/install.sh} (re-clones or fast-forwards)"
  exit 1
fi
[ "${GSTACK_CAPY_REMOTE_MIN:-}" = unknown ] && echo "gstack-capy-session: remote minimum unknown (fetch failed); the revision row is local only"
# shellcheck source=bin/gstack-install-verdict.sh
. "$ROOT/bin/gstack-install-verdict.sh"
MIN_WRAPPER=$(gstack_support_env_get "$(gstack_source_root "$ROOT/bin")" GSTACK_CAPY_MIN_WRAPPER)
if [ -n "$MIN_WRAPPER" ] && [ "${GSTACK_CAPY_WRAPPER_REV:-0}" -lt "$MIN_WRAPPER" ] 2>/dev/null; then
  echo "gstack-capy-skill: owner action — Drive copy is wrapper ${GSTACK_CAPY_WRAPPER_REV:-0}, minimum $MIN_WRAPPER; copy $ROOT/capy/skill/gstack/ (CAPY_WRAPPER_STALE)"
fi

# Behind origin? Only when the bootstrapper fetched (a known remote minimum
# means FETCH_HEAD is origin's default branch tip) and that tip is not already
# in HEAD.
behind() {
  [ -n "${GSTACK_CAPY_REMOTE_MIN:-}" ] && [ "$GSTACK_CAPY_REMOTE_MIN" != unknown ] || return 1
  git -C "$ROOT" rev-parse -q --verify FETCH_HEAD >/dev/null 2>&1 || return 1
  ! git -C "$ROOT" merge-base --is-ancestor FETCH_HEAD HEAD 2>/dev/null
}
disabled() { echo "SELF_UPGRADE: disabled ($1)"; } # VAR — the switch that turned the fast-forward off
if [ "$CHECK" -eq 1 ]; then
  if behind; then
    BRANCH=$(git -C "$ROOT" symbolic-ref -q --short HEAD 2>/dev/null || echo HEAD)
    echo "gstack-capy-session: behind origin/$BRANCH: $(head -1 "$ROOT/VERSION" 2>/dev/null) -> $(git -C "$ROOT" show FETCH_HEAD:VERSION 2>/dev/null | head -1) ($(git -C "$ROOT" rev-list --count HEAD..FETCH_HEAD 2>/dev/null || echo '?') commits); fix: bash ${GSTACK_CAPY_WRAPPER_PATH:-<skill>/scripts/install.sh}${SKILL:+ --for $SKILL} (fast-forwards)"
  fi
elif [ "${GSTACK_CAPY_SELF_UPGRADED:-}" != 1 ]; then
  if [ "${GSTACK_CAPY_SELF_UPGRADE:-}" = off ]; then disabled GSTACK_CAPY_SELF_UPGRADE
  elif [ "${GSTACK_CAPY_AUTO_UPGRADE:-1}" = 0 ]; then disabled GSTACK_CAPY_AUTO_UPGRADE
  elif [ -z "${GSTACK_CAPY_REMOTE_MIN:-}" ] || [ "$GSTACK_CAPY_REMOTE_MIN" = unknown ]; then echo "SELF_UPGRADE: none (remote minimum unknown)"
  elif ! behind; then echo "SELF_UPGRADE: none (current)"
  elif [ ! -x "$ROOT/bin/gstack-upgrade" ]; then echo "SELF_UPGRADE: skipped ($ROOT/bin/gstack-upgrade is missing)"
  else
    OLD=$(head -1 "$ROOT/VERSION" 2>/dev/null)
    UP_OUT=$("$ROOT/bin/gstack-upgrade" --ff-only-no-reinstall 2>&1); UP_RC=$?
    [ -n "$UP_OUT" ] && printf '%s\n' "$UP_OUT"
    if [ "$UP_RC" -eq 0 ]; then
      echo "SELF_UPGRADE: done $OLD -> $(head -1 "$ROOT/VERSION" 2>/dev/null)"
      export GSTACK_CAPY_UPGRADED_FROM="$OLD" GSTACK_CAPY_SELF_UPGRADED=1
      exec "$ROOT/bin/gstack-capy-session" "$@"
    fi
    REASON=$(printf '%s\n' "$UP_OUT" | sed -n 's/^gstack-upgrade: \(.*\); nothing was changed; fix: /\1; fix: /p' | tail -1)
    [ -n "$REASON" ] || REASON=$(printf '%s\n' "$UP_OUT" | sed -n 's/^gstack-upgrade: //p' | tail -1)
    echo "SELF_UPGRADE: skipped (${REASON:-gstack-upgrade exit $UP_RC})"
  fi
fi
exec "$INSTALLER" "$@"