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

usage() {
  cat <<'EOF'
Usage:
  restore.sh <backup-archive.tar.gz>

Environment:
  DEPLOY_ROOT          Deployment directory. Defaults to ~/guilan-ace-deployment.
  RESTORE_SKIP_ENV     Set to 1 to keep current .env files.
  RESTORE_SKIP_MEDIA   Set to 1 to keep current media files.
  RESTORE_SKIP_DB      Set to 1 to keep current database.

This script restores:
  - deployment, backend, and frontend .env files
  - media files into the Django media volume
  - PostgreSQL database from database.sql

Database restore is destructive unless RESTORE_SKIP_DB=1 is set.
EOF
}

log() {
  printf '[restore] %s\n' "$*"
}

fail() {
  printf '[restore] %s\n' "$*" >&2
  exit 1
}

require_file() {
  local path="$1"
  [[ -f "$path" ]] || fail "Required file not found: $path"
}

compose() {
  docker compose --env-file "$DEPLOY_ENV" -f "$DEPLOY_ROOT/docker-compose.yml" "$@"
}

wait_for_db() {
  compose exec -T db sh -c '
    set -eu
    : "${DB_USER:?DB_USER is missing}"
    : "${DB_NAME:?DB_NAME is missing}"
    until pg_isready --username="$DB_USER" --dbname="$DB_NAME" --host=127.0.0.1; do
      sleep 1
    done
  ' >/dev/null
}

restore_env_if_present() {
  local source_path="$1"
  local target_path="$2"

  if [[ -f "$source_path" ]]; then
    mkdir -p "$(dirname "$target_path")"
    cp "$source_path" "$target_path"
    chmod 600 "$target_path" || true
    log "Restored $target_path"
  fi
}

if [[ "${1:-}" == "-h" || "${1:-}" == "--help" ]]; then
  usage
  exit 0
fi

ARCHIVE_PATH="${1:-}"
[[ -n "$ARCHIVE_PATH" ]] || {
  usage
  exit 1
}

DEPLOY_ROOT="${DEPLOY_ROOT:-$HOME/guilan-ace-deployment}"
BACKEND_ENV="$DEPLOY_ROOT/backend/guilan-ace-backend/.env"
FRONTEND_ENV="$DEPLOY_ROOT/frontend/guilan-ace-frontend/.env"
DEPLOY_ENV="$DEPLOY_ROOT/.env"

require_file "$ARCHIVE_PATH"
require_file "$DEPLOY_ROOT/docker-compose.yml"

WORK_DIR="$(mktemp -d)"
trap 'rm -rf "$WORK_DIR"' EXIT

log "Extracting backup archive"
tar -C "$WORK_DIR" -xzf "$ARCHIVE_PATH"

if [[ "${RESTORE_SKIP_ENV:-0}" != "1" ]]; then
  log "Restoring environment files"
  restore_env_if_present "$WORK_DIR/env/deployment.env" "$DEPLOY_ENV"
  restore_env_if_present "$WORK_DIR/env/backend.env" "$BACKEND_ENV"
  restore_env_if_present "$WORK_DIR/env/frontend.env" "$FRONTEND_ENV"
else
  log "Skipping environment restore"
fi

require_file "$BACKEND_ENV"
require_file "$DEPLOY_ENV"

log "Checking Docker Compose configuration"
compose config -q

if [[ "${RESTORE_SKIP_MEDIA:-0}" != "1" ]]; then
  require_file "$WORK_DIR/media.tar.gz"
  log "Restoring media files into Django media volume"
  compose run --rm --no-deps --entrypoint sh web -c 'rm -rf /app/media/* /app/media/.[!.]* /app/media/..?* 2>/dev/null || true'
  compose run --rm --no-deps -T --entrypoint sh web -c 'mkdir -p /app/media && tar -C /app/media -xzf -' < "$WORK_DIR/media.tar.gz"
else
  log "Skipping media restore"
fi

if [[ "${RESTORE_SKIP_DB:-0}" != "1" ]]; then
  require_file "$WORK_DIR/database.sql"
  log "Starting database service"
  compose up -d db
  wait_for_db

  log "Recreating and restoring database"
  compose exec -T db sh -c '
    set -eu
    : "${DB_USER:?DB_USER is missing}"
    : "${DB_NAME:?DB_NAME is missing}"
    psql --username="$DB_USER" --dbname=postgres --command="SELECT pg_terminate_backend(pid) FROM pg_stat_activity WHERE datname = '\''$DB_NAME'\'' AND pid <> pg_backend_pid();" >/dev/null
    dropdb --username="$DB_USER" --if-exists "$DB_NAME"
    createdb --username="$DB_USER" "$DB_NAME"
    psql --username="$DB_USER" --dbname="$DB_NAME"
  ' < "$WORK_DIR/database.sql"
else
  log "Skipping database restore"
fi

log "Restore completed"
log "Run: docker compose up -d --build"