class Multiwoven::Integrations::Source::WatsonxData::Client

def batched_query_for_presto(query, limit, offset)
  <<~SQL
    SELECT * FROM (
      SELECT *, ROW_NUMBER() OVER () as rownum FROM ( #{query} ) subquery
    ) t
    WHERE rownum > #{offset}
    LIMIT #{limit}
  SQL
end

def check_connection(connection_config)
  create_connection(connection_config)
  response = execute_query(connection_config, "show catalogs")
  success?(response) ? success_status : failure_status(nil)
rescue StandardError => e
  handle_exception(e, { context: "WATSONX DATA:CHECK_CONNECTION:EXCEPTION", type: "error" })
  failure_status(e)
end

def create_connection(connection_config)
  connection_config
end

def create_streams(records)
  group_by_table(records).map do |r|
    Multiwoven::Integrations::Protocol::Stream.new(name: r[:tablename], action: StreamAction["fetch"], json_schema: convert_to_json_schema(r[:columns]))
  end
end

def discover(connection_config)
  connection_config = connection_config.with_indifferent_access
  query = "SELECT table_name, column_name,
            data_type,
            is_nullable
            FROM information_schema.columns
            WHERE table_schema = '#{connection_config[:schema]}' AND table_catalog = '#{connection_config[:database]}'
            ORDER BY table_name, ordinal_position"
  response = execute_query(connection_config, query)
  records = JSON.parse(response.body)["response"]["result"]
  catalog = Catalog.new(streams: create_streams(records))
  catalog.to_multiwoven_message
rescue StandardError => e
  handle_exception(e, { context: "WATSONX DATA:DISCOVER:EXCEPTION", type: "error" })
end

def execute_query(connection_config, query)
  connection_config.with_indifferent_access
  get_access_token(connection_config[:api_key])
  url = format(
    WATSONX_DATA_QUERIES_URL,
    region: connection_config[:region],
    engine_id: connection_config[:engine_id]
  )
  headers = auth_headers(@access_token)
  headers["AuthInstanceId"] = connection_config[:auth_instance_id]
  send_request(
    url: url,
    http_method: HTTP_POST,
    payload: {
      sql_string: query,
      catalog_name: connection_config[:database],
      schema_name: connection_config[:schema]
    },
    headers: headers,
    config: connection_config[:config]
  )
end

def get_access_token(api_key)
  cache = defined?(Rails) && Rails.respond_to?(:cache) ? Rails.cache : ActiveSupport::Cache::MemoryStore.new
  cache_key = "watsonx_data_#{api_key}"
  cached_token = cache.read(cache_key)
  if cached_token
    @access_token = cached_token
  else
    new_token = get_iam_token(api_key)
    # puts new_token
    # max expiration is 3 minutes. No way to make it higher
    cache.write(cache_key, new_token, expires_in: 180)
    @access_token = new_token
  end
end

def get_iam_token(api_key)
  uri = URI("https://iam.cloud.ibm.com/identity/token")
  request = Net::HTTP::Post.new(uri)
  request["Content-Type"] = "application/x-www-form-urlencoded"
  request.body = "grant_type=urn:ibm:params:oauth:grant-type:apikey&apikey=#{api_key}"
  response = Net::HTTP.start(uri.hostname, uri.port, use_ssl: true) do |http|
    http.request(request)
  end
  raise "Failed to get IAM token: #{response.body}" unless response.is_a?(Net::HTTPSuccess)
  JSON.parse(response.body)["access_token"]
end

def group_by_table(records)
  records.group_by { |entry| entry["table_name"] }.map do |table_name, columns|
    {
      tablename: table_name,
      columns: columns.map do |column|
        {
          column_name: column["column_name"],
          type: column["data_type"],
          optional: column["is_nullable"] == "YES"
        }
      end
    }
  end
end

def query(connection, query)
  response = execute_query(connection, query)
  response = JSON.parse(response.body).with_indifferent_access
  records = response[:response][:result]
  records.map do |row|
    RecordMessage.new(data: row, emitted_at: Time.now.to_i).to_multiwoven_message
  end
end

def read(sync_config)
  connection_config = sync_config.source.connection_specification
  connection_config = connection_config.with_indifferent_access
  query = sync_config.model.query
  if connection_config[:engine] == "presto"
    query = batched_query_for_presto(query, sync_config.limit, sync_config.offset) unless sync_config.limit.nil? && sync_config.offset.nil?
  else
    query = batched_query(query, sync_config.limit, sync_config.offset) unless sync_config.limit.nil? && sync_config.offset.nil?
  end
  query(connection_config, query)
rescue StandardError => e
  handle_exception(e, { context: "WATSONX DATA:READ:EXCEPTION", type: "error" })
end