class Multiwoven::Integrations::Source::Clickhouse::Client

def check_connection(connection_config)
  connection_config = connection_config.with_indifferent_access
  create_connection(connection_config)
  ConnectionStatus.new(
    status: ConnectionStatusType["succeeded"]
  ).to_multiwoven_message
rescue StandardError => e
  ConnectionStatus.new(
    status: ConnectionStatusType["failed"], message: e.message
  ).to_multiwoven_message
end

def create_connection(connection_config)
  @auth_token = Base64.strict_encode64("#{connection_config[:username]}:#{connection_config[:password]}")
  Faraday.new(connection_config[:host]) do |faraday|
    faraday.request :url_encoded
    faraday.adapter Faraday.default_adapter
  end
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[:database]}' ORDER BY table_name, ordinal_position;"
  db = create_connection(connection_config)
  records = query_execution(db, query)
  catalog = Catalog.new(streams: create_streams(records))
  catalog.to_multiwoven_message
rescue StandardError => e
  handle_exception(e, {
                     context: "CLICKHOUSE:DISCOVER:EXCEPTION",
                     type: "error"
                   })
end

def group_by_table(records)
  result = {}
  records.each_with_index do |entry, index|
    table_name = entry["table_name"]
    column_data = {
      column_name: entry["column_name"],
      data_type: entry["data_type"].gsub(/Nullable\((\w+)\)/, '\1').downcase.gsub!(/\d+/, ""),
      is_nullable: entry["is_nullable"] == "1"
    }
    result[index] ||= {}
    result[index][:tablename] = table_name
    result[index][:columns] = [column_data]
  end
  result
end

def query(connection, query)
  query_execution(connection, query).map do |row|
    RecordMessage.new(data: row, emitted_at: Time.now.to_i).to_multiwoven_message
  end
end

def query_execution(connection, query)
  response = connection.post do |req|
    req.url "/"
    req.headers["Authorization"] = "Basic #{@auth_token}"
    req.headers["Content-Type"] = "text/plain"
    req.body = query
  end
  column_names = query[/SELECT (.*?) FROM/i, 1].split(",").map(&:strip)
  response.body.strip.split("\n").map do |row|
    columns = row.split("\t")
    column_names.zip(columns).to_h
  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
  query = batched_query(query, sync_config.limit, sync_config.offset) unless sync_config.limit.nil? && sync_config.offset.nil?
  db = create_connection(connection_config)
  query(db, query)
rescue StandardError => e
  handle_exception(e, {
                     context: "CLICKHOUSE:READ:EXCEPTION",
                     type: "error",
                     sync_id: sync_config.sync_id,
                     sync_run_id: sync_config.sync_run_id
                   })
end