class ActiveRecord::ConnectionAdapters::SQLite3Adapter

def active?
  @active != false
end

def adapter_name #:nodoc:
  'SQLite'
end

def add_column(table_name, column_name, type, options = {}) #:nodoc:
  if supports_add_column? && valid_alter_table_options( type, options )
    super(table_name, column_name, type, options)
  else
    alter_table(table_name) do |definition|
      definition.column(column_name, type, options)
    end
  end
end

def allowed_index_name_length
  index_name_length - 2
end

def alter_table(table_name, options = {}) #:nodoc:
  altered_table_name = "a#{table_name}"
  caller = lambda {|definition| yield definition if block_given?}
  transaction do
    move_table(table_name, altered_table_name,
      options.merge(:temporary => true))
    move_table(altered_table_name, table_name, &caller)
  end
end

def begin_db_transaction #:nodoc:
  log('begin transaction',nil) { @connection.transaction }
end

def change_column(table_name, column_name, type, options = {}) #:nodoc:
  alter_table(table_name) do |definition|
    include_default = options_include_default?(options)
    definition[column_name].instance_eval do
      self.type    = type
      self.limit   = options[:limit] if options.include?(:limit)
      self.default = options[:default] if include_default
      self.null    = options[:null] if options.include?(:null)
      self.precision = options[:precision] if options.include?(:precision)
      self.scale   = options[:scale] if options.include?(:scale)
    end
  end
end

def change_column_default(table_name, column_name, default) #:nodoc:
  alter_table(table_name) do |definition|
    definition[column_name].default = default
  end
end

def change_column_null(table_name, column_name, null, default = nil)
  unless null || default.nil?
    exec_query("UPDATE #{quote_table_name(table_name)} SET #{quote_column_name(column_name)}=#{quote(default)} WHERE #{quote_column_name(column_name)} IS NULL")
  end
  alter_table(table_name) do |definition|
    definition[column_name].null = null
  end
end

def clear_cache!
  @statements.clear
end

def columns(table_name) #:nodoc:
  table_structure(table_name).map do |field|
    case field["dflt_value"]
    when /^null$/i
      field["dflt_value"] = nil
    when /^'(.*)'$/m
      field["dflt_value"] = $1.gsub("''", "'")
    when /^"(.*)"$/m
      field["dflt_value"] = $1.gsub('""', '"')
    end
    SQLite3Column.new(field['name'], field['dflt_value'], field['type'], field['notnull'].to_i == 0)
  end
end

def commit_db_transaction #:nodoc:
  log('commit transaction',nil) { @connection.commit }
end

def copy_table(from, to, options = {}) #:nodoc:
  from_primary_key = primary_key(from)
  options[:id] = false
  create_table(to, options) do |definition|
    @definition = definition
    @definition.primary_key(from_primary_key) if from_primary_key.present?
    columns(from).each do |column|
      column_name = options[:rename] ?
        (options[:rename][column.name] ||
         options[:rename][column.name.to_sym] ||
         column.name) : column.name
      next if column_name == from_primary_key
      @definition.column(column_name, column.type,
        :limit => column.limit, :default => column.default,
        :precision => column.precision, :scale => column.scale,
        :null => column.null)
    end
    yield @definition if block_given?
  end
  copy_table_indexes(from, to, options[:rename] || {})
  copy_table_contents(from, to,
    @definition.columns.map {|column| column.name},
    options[:rename] || {})
end

def copy_table_contents(from, to, columns, rename = {}) #:nodoc:
  column_mappings = Hash[columns.map {|name| [name, name]}]
  rename.each { |a| column_mappings[a.last] = a.first }
  from_columns = columns(from).collect {|col| col.name}
  columns = columns.find_all{|col| from_columns.include?(column_mappings[col])}
  quoted_columns = columns.map { |col| quote_column_name(col) } * ','
  quoted_to = quote_table_name(to)
  raw_column_mappings = Hash[columns(from).map { |c| [c.name, c] }]
  exec_query("SELECT * FROM #{quote_table_name(from)}").each do |row|
    sql = "INSERT INTO #{quoted_to} (#{quoted_columns}) VALUES ("
    column_values = columns.map do |col|
      quote(row[column_mappings[col]], raw_column_mappings[col])
    end
    sql << column_values * ', '
    sql << ')'
    exec_query sql
  end
end

def copy_table_indexes(from, to, rename = {}) #:nodoc:
  indexes(from).each do |index|
    name = index.name
    if to == "a#{from}"
      name = "t#{name}"
    elsif from == "a#{to}"
      name = name[1..-1]
    end
    to_column_names = columns(to).map { |c| c.name }
    columns = index.columns.map {|c| rename[c] || c }.select do |column|
      to_column_names.include?(column)
    end
    unless columns.empty?
      # index name can't be the same
      opts = { name: name.gsub(/(^|_)(#{from})_/, "\\1#{to}_"), internal: true }
      opts[:unique] = true if index.unique
      add_index(to, columns, opts)
    end
  end
end

def delete_sql(sql, name = nil) #:nodoc:
  sql += " WHERE 1=1" unless sql =~ /WHERE/i
  super sql, name
end

def disconnect!
  super
  @active = false
  @connection.close rescue nil
end

def encoding
  @connection.encoding.to_s
end

def exec_delete(sql, name = 'SQL', binds = [])
  exec_query(sql, name, binds)
  @connection.changes
end

def exec_query(sql, name = nil, binds = [])
  type_casted_binds = binds.map { |col, val|
    [col, type_cast(val, col)]
  }
  log(sql, name, type_casted_binds) do
    # Don't cache statements if they are not prepared
    if without_prepared_statement?(binds)
      stmt    = @connection.prepare(sql)
      cols    = stmt.columns
      records = stmt.to_a
      stmt.close
      stmt = records
    else
      cache = @statements[sql] ||= {
        :stmt => @connection.prepare(sql)
      }
      stmt = cache[:stmt]
      cols = cache[:cols] ||= stmt.columns
      stmt.reset!
      stmt.bind_params type_casted_binds.map { |_, val| val }
    end
    ActiveRecord::Result.new(cols, stmt.to_a)
  end
end

def execute(sql, name = nil) #:nodoc:
  log(sql, name) { @connection.execute(sql) }
end

def explain(arel, binds = [])
  sql = "EXPLAIN QUERY PLAN #{to_sql(arel, binds)}"
  ExplainPrettyPrinter.new.pp(exec_query(sql, 'EXPLAIN', binds))
end

def indexes(table_name, name = nil) #:nodoc:
  exec_query("PRAGMA index_list(#{quote_table_name(table_name)})", 'SCHEMA').map do |row|
    sql = <<-SQL
      SELECT sql
      FROM sqlite_master
      WHERE name=#{quote(row['name'])} AND type='index'
      UNION ALL
      SELECT sql
      FROM sqlite_temp_master
      WHERE name=#{quote(row['name'])} AND type='index'
    SQL
    index_sql = exec_query(sql).first['sql']
    match = /\sWHERE\s+(.+)$/i.match(index_sql)
    where = match[1] if match
    IndexDefinition.new(
      table_name,
      row['name'],
      row['unique'] != 0,
      exec_query("PRAGMA index_info('#{row['name']}')", "SCHEMA").map { |col|
        col['name']
      }, nil, nil, where)
  end
end

def initialize(connection, logger, config)
  super(connection, logger)
  @active     = nil
  @statements = StatementPool.new(@connection,
                                  self.class.type_cast_config_to_integer(config.fetch(:statement_limit) { 1000 }))
  @config = config
  if self.class.type_cast_config_to_boolean(config.fetch(:prepared_statements) { true })
    @prepared_statements = true
    @visitor = Arel::Visitors::SQLite.new self
  else
    @visitor = unprepared_visitor
  end
end

def insert_sql(sql, name = nil, pk = nil, id_value = nil, sequence_name = nil) #:nodoc:
  super
  id_value || @connection.last_insert_row_id
end

def last_inserted_id(result)
  @connection.last_insert_row_id
end

def move_table(from, to, options = {}, &block) #:nodoc:
  copy_table(from, to, options, &block)
  drop_table(from)
end

def native_database_types #:nodoc:
  NATIVE_DATABASE_TYPES
end

def primary_key(table_name) #:nodoc:
  column = table_structure(table_name).find { |field|
    field['pk'] == 1
  }
  column && column['name']
end

def quote(value, column = nil)
  if value.kind_of?(String) && column && column.type == :binary
    s = value.unpack("H*")[0]
    "x'#{s}'"
  else
    super
  end
end

def quote_column_name(name) #:nodoc:
  %Q("#{name.to_s.gsub('"', '""')}")
end

def quote_string(s) #:nodoc:
  @connection.class.quote(s)
end

def quote_table_name_for_assignment(table, attr)
  quote_column_name(attr)
end

def quoted_date(value) #:nodoc:
  if value.respond_to?(:usec)
    "#{super}.#{sprintf("%06d", value.usec)}"
  else
    super
  end
end

def remove_column(table_name, column_name, type = nil, options = {}) #:nodoc:
  alter_table(table_name) do |definition|
    definition.remove_column column_name
  end
end

def remove_index!(table_name, index_name) #:nodoc:
  exec_query "DROP INDEX #{quote_column_name(index_name)}"
end

def rename_column(table_name, column_name, new_column_name) #:nodoc:
  unless columns(table_name).detect{|c| c.name == column_name.to_s }
    raise ActiveRecord::ActiveRecordError, "Missing column #{table_name}.#{column_name}"
  end
  alter_table(table_name, :rename => {column_name.to_s => new_column_name.to_s})
  rename_column_indexes(table_name, column_name, new_column_name)
end

def rename_table(table_name, new_name)
  exec_query "ALTER TABLE #{quote_table_name(table_name)} RENAME TO #{quote_table_name(new_name)}"
  rename_table_indexes(table_name, new_name)
end

def requires_reloading?
  true
end

def rollback_db_transaction #:nodoc:
  log('rollback transaction',nil) { @connection.rollback }
end

def select(sql, name = nil, binds = []) #:nodoc:
  exec_query(sql, name, binds)
end

def select_rows(sql, name = nil, binds = [])
  exec_query(sql, name, binds).rows
end

def sqlite_version
  @sqlite_version ||= SQLite3Adapter::Version.new(select_value('select sqlite_version(*)'))
end

def supports_add_column?
  true
end

def supports_ddl_transactions?
  true
end

def supports_explain?
  true
end

def supports_index_sort_order?
  true
end

def supports_migrations? #:nodoc:
  true
end

def supports_partial_index?
  sqlite_version >= '3.8.0'
end

def supports_primary_key? #:nodoc:
  true
end

def supports_savepoints?
  true
end

def supports_statement_cache?
  true
end

def table_exists?(table_name)
  table_name && tables(nil, table_name).any?
end

def table_structure(table_name)
  structure = exec_query("PRAGMA table_info(#{quote_table_name(table_name)})", 'SCHEMA').to_hash
  raise(ActiveRecord::StatementInvalid, "Could not find table '#{table_name}'") if structure.empty?
  structure
end

def tables(name = nil, table_name = nil) #:nodoc:
  sql = <<-SQL
    SELECT name
    FROM sqlite_master
    WHERE type = 'table' AND NOT name = 'sqlite_sequence'
  SQL
  sql << " AND name = #{quote_table_name(table_name)}" if table_name
  exec_query(sql, 'SCHEMA').map do |row|
    row['name']
  end
end

def translate_exception(exception, message)
  case exception.message
  # SQLite 3.8.2 returns a newly formatted error message:
  #   UNIQUE constraint failed: *table_name*.*column_name*
  # Older versions of SQLite return:
  #   column *column_name* is not unique
  when /column(s)? .* (is|are) not unique/, /UNIQUE constraint failed: .*/
    RecordNotUnique.new(message, exception)
  else
    super
  end
end

def type_cast(value, column) # :nodoc:
  return value.to_f if BigDecimal === value
  return super unless String === value
  return super unless column && value
  value = super
  if column.type == :string && value.encoding == Encoding::ASCII_8BIT
    logger.error "Binary data inserted for `string` type on column `#{column.name}`" if logger
    value = value.encode Encoding::UTF_8
  end
  value
end

def update_sql(sql, name = nil) #:nodoc:
  super
  @connection.changes
end

def valid_alter_table_options( type, options)
  type.to_sym != :primary_key
end