#!/usr/bin/env bash
# gstack-ios-qa-regen — deterministically regenerate the iOS DebugBridge
# package and the app-owned typed state accessors.

set -euo pipefail

usage() {
  cat <<'EOF'
Usage: gstack-ios-qa-regen --app-source <dir> --bridge-dir <dir>

  --app-source  Swift source tree to scan for @Observable state
  --bridge-dir  Destination for the generated local DebugBridge package
EOF
}

APP_SOURCE=""
BRIDGE_DIR=""

while [[ $# -gt 0 ]]; do
  case "$1" in
    --app-source)
      [[ $# -ge 2 ]] || { echo "gstack-ios-qa-regen: --app-source requires a value" >&2; exit 2; }
      APP_SOURCE="$2"
      shift 2
      ;;
    --bridge-dir)
      [[ $# -ge 2 ]] || { echo "gstack-ios-qa-regen: --bridge-dir requires a value" >&2; exit 2; }
      BRIDGE_DIR="$2"
      shift 2
      ;;
    -h|--help)
      usage
      exit 0
      ;;
    *)
      echo "gstack-ios-qa-regen: unknown argument: $1" >&2
      usage >&2
      exit 2
      ;;
  esac
done

if [[ -z "$APP_SOURCE" || -z "$BRIDGE_DIR" ]]; then
  echo "gstack-ios-qa-regen: both --app-source and --bridge-dir are required" >&2
  usage >&2
  exit 2
fi

if [[ ! -d "$APP_SOURCE" ]]; then
  echo "gstack-ios-qa-regen: app source directory not found: $APP_SOURCE" >&2
  exit 1
fi

if ! command -v bun >/dev/null 2>&1; then
  echo "gstack-ios-qa-regen: bun runtime not on PATH — install from https://bun.sh" >&2
  exit 1
fi

SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
GSTACK_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
TEMPLATE_DIR="$GSTACK_ROOT/ios-qa/templates"
GENERATOR="$GSTACK_ROOT/ios-qa/scripts/gen-accessors.ts"
VERSION_FILE="$GSTACK_ROOT/VERSION"
GENERATED_DIR="$APP_SOURCE/DebugBridgeGenerated"

for required in "$GENERATOR" "$VERSION_FILE"; do
  if [[ ! -f "$required" ]]; then
    echo "gstack-ios-qa-regen: missing required gstack file: $required" >&2
    exit 1
  fi
done

TMP_FILE=""
cleanup() {
  if [[ -n "$TMP_FILE" ]]; then
    rm -f "$TMP_FILE"
  fi
}
trap cleanup EXIT

# Copy through a sibling temporary file so interruption never leaves a
# truncated generated source. Preserve an unchanged destination byte-for-byte
# and metadata-for-metadata on repeated runs.
install_file() {
  local source="$1"
  local destination="$2"

  if [[ ! -f "$source" ]]; then
    echo "gstack-ios-qa-regen: missing template: $source" >&2
    exit 1
  fi
  if [[ -f "$destination" ]] && cmp -s "$source" "$destination"; then
    return
  fi

  mkdir -p "$(dirname "$destination")"
  TMP_FILE="${destination}.tmp.$$"
  cp "$source" "$TMP_FILE"
  mv "$TMP_FILE" "$destination"
  TMP_FILE=""
}

# Invalidate the completion marker before changing any package source. A
# failed or interrupted regeneration must never look current to ios-sync.
mkdir -p "$GENERATED_DIR"
rm -f -- "$GENERATED_DIR/.gstack-version"

# This is intentionally an allowlist, not a template glob. Wiring belongs to
# the consuming app and StateAccessor.swift is emitted by the parser below.
install_file "$TEMPLATE_DIR/Package.swift.template" \
  "$BRIDGE_DIR/Package.swift"
install_file "$TEMPLATE_DIR/StateServer.swift.template" \
  "$BRIDGE_DIR/Sources/DebugBridgeCore/StateServer.swift"
install_file "$TEMPLATE_DIR/DebugBridgeManager.swift.template" \
  "$BRIDGE_DIR/Sources/DebugBridgeCore/DebugBridgeManager.swift"
install_file "$TEMPLATE_DIR/Bridges.swift.template" \
  "$BRIDGE_DIR/Sources/DebugBridgeUI/Bridges.swift"
install_file "$TEMPLATE_DIR/DebugOverlay.swift.template" \
  "$BRIDGE_DIR/Sources/DebugBridgeUI/DebugOverlay.swift"
install_file "$TEMPLATE_DIR/DebugBridgeTouch.m.template" \
  "$BRIDGE_DIR/Sources/DebugBridgeTouch/DebugBridgeTouch.m"
install_file "$TEMPLATE_DIR/DebugBridgeTouch.h.template" \
  "$BRIDGE_DIR/Sources/DebugBridgeTouch/include/DebugBridgeTouch.h"

# Older ios-sync versions copied the entire template set flat into the app's
# generated-source directory. Those files can shadow the package modules or
# make Xcode compile two harness implementations. Remove only the explicit
# obsolete generated paths; handwritten app sources are never touched.
for obsolete in \
  "$BRIDGE_DIR/DebugBridgeWiring.swift" \
  "$BRIDGE_DIR/StateAccessor.swift" \
  "$GENERATED_DIR/Package.swift" \
  "$GENERATED_DIR/StateServer.swift" \
  "$GENERATED_DIR/DebugBridgeManager.swift" \
  "$GENERATED_DIR/Bridges.swift" \
  "$GENERATED_DIR/DebugOverlay.swift" \
  "$GENERATED_DIR/DebugBridgeTouch.m" \
  "$GENERATED_DIR/DebugBridgeTouch.h" \
  "$GENERATED_DIR/DebugBridgeWiring.swift"
do
  if [[ -f "$obsolete" || -L "$obsolete" ]]; then
    rm -f -- "$obsolete"
    echo "gstack-ios-qa-regen: removed obsolete generated file $obsolete"
  fi
done

bun run "$GENERATOR" --input "$APP_SOURCE" --output "$GENERATED_DIR"

# Stamp only after successful accessor generation. ios-sync uses this marker
# to distinguish a complete current install from an interrupted regeneration.
install_file "$VERSION_FILE" "$GENERATED_DIR/.gstack-version"

echo "gstack-ios-qa-regen: bridge package ready at $BRIDGE_DIR"
echo "gstack-ios-qa-regen: accessors ready at $GENERATED_DIR/StateAccessor.swift"