require File.join(File.dirname(__FILE__), "service")

module Charrington
  class CreateRedshiftTable
    # This service will create a table dynamically based on the JSON structure.
    # This is potentially called from Insert when an insert fails.

    include Service
    include LogStash::Util::Loggable
    attr_reader :connection, :event, :table_name, :columns, :schema
    attr_accessor :column_types

    Error = Class.new(StandardError)
    CreateFailed = Class.new(Error)

    def initialize(connection, event, schema, table_name, columns)
      @connection = connection
      @event = event.to_hash
      @schema = schema
      @table_name = table_name
      @columns = columns
      @column_types = initial_columns
    end

    def call
      set_column_types
      create_table
      true
    rescue => e
      raise CreateFailed, e.message
    ensure
      @column_types.clear if @column_types.is_a? Array
    end

    private

    # https://docs.aws.amazon.com/redshift/latest/dg/r_CREATE_TABLE_NEW.html
    def set_column_types
      columns.each do |column|
        if column == "id"
          column_types << "#{column} VARCHAR(512) NOT NULL distkey CONSTRAINT #{table_name}_pkey primary key"
          next
        end
        case event[column]
        when Time, LogStash::Timestamp
          column_types << "#{column} TIMESTAMP"
        when Date
          column_types << "#{column} DATE"
        when Integer
          column_types << "#{column} BIGINT"
        when BigDecimal
          column_types << "#{column} DECIMAL"
        when Float
          column_types << "#{column} DOUBLE PRECISION"
        when true, false
          column_types << "#{column} BOOLEAN"
        else
          column_types << "#{column} VARCHAR(512)"
        end
      end
    end

    def initial_columns
      [
        'original_timestamp TIMESTAMP DEFAULT GETDATE()',
        'received_at TIMESTAMP DEFAULT GETDATE()',
        'timestamp TIMESTAMP DEFAULT GETDATE()',
        'uuid_ts TIMESTAMP DEFAULT GETDATE()',
        "uuid bigint default \"identity\"(22828367, 2, '1,1'::text)"
      ]
    end

    def create_table
      execute("CREATE TABLE IF NOT EXISTS #{schema}#{table_name} (#{column_types.join(', ')}) diststyle key sortkey(received_at)")
    end

    def execute(sql)
      statement = connection.prepareStatement( sql.gsub(/\s+/, " ").strip )
      statement.execute()
    rescue Java::JavaSql::SQLException => e
      puts "Redshift SQLException: #{e.message}"
      self.logger.info "Redshift SQLException: #{e.message}"
    ensure
      statement.close unless statement.nil?
    end
  end
end