module Flydata
module TableDef

class MysqlTableDef
  TYPE_MAP_M2F = {
    'bigint' => 'int8',
    'binary' => 'binary',
    'blob' => 'varbinary(65535)',
    'bool' => 'int1',
    'boolean' => 'int1',
    'char' => 'varchar',
    'date' => 'date',
    'datetime' => 'datetime',
    'dec' => 'numeric',
    'decimal' => 'numeric',
    'double' => 'float8',
    'double precision' => 'float8',
    'enum' => 'enum',
    'fixed' => 'numeric',
    'float' => 'float4',
    'int' => 'int4',
    'integer' => 'int4',
    'longblob' => 'varbinary(4294967295)',
    'longtext' => 'text',
    'mediumblob' => 'varbinary(16777215)',
    'mediumint' => 'int3',
    'mediumtext' => 'text',
    'numeric' => 'numeric',
    'smallint' => 'int2',
    'text' => 'text',
    'time' => 'time',
    'timestamp' => 'datetime',
    'tinyblob' => 'varbinary(255)',
    'tinyint' => 'int1',
    'tinytext' => 'text',
    'varbinary' => 'varbinary',
    'varchar' => 'varchar',
  }

  def self.convert_to_flydata_type(type)
    TYPE_MAP_M2F.each do |mysql_type, flydata_type|
      if /^#{mysql_type}\(|^#{mysql_type}$/.match(type)
        ret_type = type.gsub(/^#{mysql_type}/, flydata_type)
        ret_type = check_and_set_varchar_length(ret_type, mysql_type, flydata_type)
        return ret_type
      end
    end
    nil
  end

  # Check and set the varchar(char) size which is converted from
  # length to byte size.
  # On Mysql the record size of varchar(char) is a length of characters.
  # ex) varchar(6) on mysql -> varchar(18) on flydata
  def self.check_and_set_varchar_length(type, mysql_type, flydata_type)
    return type unless %w(char varchar).include?(mysql_type)
    if type =~ /\((\d+)\)/
      # expect 3 byte UTF-8 character
      "#{flydata_type}(#{$1.to_i * 3})"
    else
      raise "Invalid varchar type. It must be a bug... type:#{type}"
    end
  end

  def self.create(io)
    params = _create(io)
    params ? self.new(*params) : nil
  end

  def initialize(table_def, table_name, columns, default_charset, comment)
    @table_def = table_def
    @table_name = table_name
    @columns = columns
    @default_charset = default_charset
    @comment = comment
  end

  def self._create(io)
    table_def = ''
    table_name = nil
    columns = []
    default_charset = nil
    comment = nil

    position = :before_create_table

    io.each_line do |line|
      case position
      when :before_create_table
        if line =~ /CREATE TABLE `(.*?)`/
          position = :in_create_table
          table_name = $1
          table_def += line.chomp
          next
        end

      when :in_create_table
        table_def += line.chomp

        stripped_line = line.strip
        # `col_smallint` smallint(6) DEFAULT NULL,
        if stripped_line.start_with?('`')
          columns << parse_one_column_def(line)
        # PRIMARY KEY (`id`)
        elsif stripped_line.start_with?("PRIMARY KEY")
          parse_key(line, columns)
        #) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='test table';
        elsif stripped_line.start_with?(')')
          default_charset = $1 if line =~ /DEFAULT CHARSET\s*=\s*([^\s]+)/
          comment = $1 if /COMMENT='((?:\\'|[^'])*)'/.match(line)
          position = :after_create_table
        elsif stripped_line.start_with?("KEY")
          # index creation.  No action required.
        elsif stripped_line.start_with?("CONSTRAINT")
          # constraint definition.  No acction required.
        elsif stripped_line.start_with?("UNIQUE KEY")
          parse_key(line, columns, :unique)
        else
          $stderr.puts "Unknown table definition. Skip. (#{line})"
        end

      when :after_create_table
        unless columns.any? {|column| column[:primary_key]}
          raise TableDefError, {error: "no primary key defined", table: table_name}
        end
        break
      end
    end
    position == :after_create_table ? [table_def, table_name, columns, default_charset, comment] : nil
  end
  attr_reader :columns, :table_name

  def to_flydata_tabledef
    tabledef = { table_name: @table_name,
                 columns: @columns,
               }
    tabledef[:default_charset] = @default_charset if @default_charset
    tabledef[:comment] = @comment if @comment

    tabledef
  end

  def self.parse_one_column_def(query)
    line = query.strip
    line = line[0..-2] if line.end_with?(',')
    pos = 0
    cond = :column_name
    column = {}

    while pos < line.length
      case cond
      when :column_name  #`column_name` ...
        pos = line.index(' ', 1)
        column[:column] = if line[0] == '`'
                          line[1..pos-2]
                        else
                          line[0..pos-1]
                        end
        cond = :column_type
        pos += 1
      when :column_type  #... formattype(,,,) ...
        pos += 1 until line[pos] != ' '
        start_pos = pos
        pos += 1 until line[pos].nil? || line[pos] =~ /\s|\(/

        # meta
        if line[pos] == '('
          #TODO: implement better parser
          pos = line.index(')', pos)
          pos += 1
        end

        # type
        type = line[start_pos..pos-1]
        column[:type] = convert_to_flydata_type(type)

        cond = :options
      when :options
        column[:type] += ' unsigned' if line =~ /unsigned/i
        column[:auto_increment] = true if line =~ /AUTO_INCREMENT/i
        column[:not_null] = true if line =~ /NOT NULL/i
        column[:unique] = true if line =~ /UNIQUE/i
        if /DEFAULT\s+((?:[^'\s]+\b)|(?:'(?:\\'|[^'])*'))/i.match(line)
          val = $1
          val = val.slice(1..-1) if val.start_with?("'")
          val = val.slice(0..-2) if val.end_with?("'")
          column[:default] = val == "NULL" ? nil : val
        end
        if /COMMENT\s+'(((?:\\'|[^'])*))'/i.match(line)
          column[:comment] = $1
        end
        if block_given?
          column = yield(column, query, pos)
        end
        break
      else
        raise "Invalid condition. It must be a bug..."
      end
    end
    column
  end

  private

  def self.parse_key(line, columns, type = :primary_key)
    line = /\((?:`.*?`(?:,\s*)?)+\)/.match(line)[0]
    keys = line.scan(/`(.*?)`/).collect{|item| item[0]}

    keys.each do |key|
      column = columns.detect {|column|
        column[:column] === key
      }
      raise "Key #{key} must exist in the definition " if column.nil?
      column[type] = true
    end
  end
end

end
end