class ActiveRecord::ConnectionAdapters::SQLite3Adapter

def active?
  if connected?
    verified!
    true
  end
end

def add_column(table_name, column_name, type, **options) # :nodoc:
  type = type.to_sym
  if invalid_alter_table_type?(type, options)
    alter_table(table_name) do |definition|
      definition.column(column_name, type, **options)
    end
  else
    super
  end
end

def add_reference(table_name, ref_name, **options) # :nodoc:
  super(table_name, ref_name, type: :integer, **options)
end

def add_timestamps(table_name, **options)
  options[:null] = false if options[:null].nil?
  if !options.key?(:precision)
    options[:precision] = 6
  end
  alter_table(table_name) do |definition|
    definition.column :created_at, :datetime, **options
    definition.column :updated_at, :datetime, **options
  end
end

def alter_table(
  table_name,
  foreign_keys = foreign_keys(table_name),
  check_constraints = check_constraints(table_name),
  **options
)
  altered_table_name = "a#{table_name}"
  caller = lambda do |definition|
    rename = options[:rename] || {}
    foreign_keys.each do |fk|
      if column = rename[fk.options[:column]]
        fk.options[:column] = column
      end
      to_table = strip_table_name_prefix_and_suffix(fk.to_table)
      definition.foreign_key(to_table, **fk.options)
    end
    check_constraints.each do |chk|
      definition.check_constraint(chk.expression, **chk.options)
    end
    yield definition if block_given?
  end
  transaction do
    disable_referential_integrity do
      move_table(table_name, altered_table_name, options.merge(temporary: true))
      move_table(altered_table_name, table_name, &caller)
    end
  end
end

def arel_visitor
  Arel::Visitors::SQLite.new(self)
end

def bind_params_length
  999
end

def build_insert_sql(insert) # :nodoc:
  sql = +"INSERT #{insert.into} #{insert.values_list}"
  if insert.skip_duplicates?
    sql << " ON CONFLICT #{insert.conflict_target} DO NOTHING"
  elsif insert.update_duplicates?
    sql << " ON CONFLICT #{insert.conflict_target} DO UPDATE SET "
    if insert.raw_update_sql?
      sql << insert.raw_update_sql
    else
      sql << insert.touch_model_timestamps_unless { |column| "#{column} IS excluded.#{column}" }
      sql << insert.updatable_columns.map { |column| "#{column}=excluded.#{column}" }.join(",")
    end
  end
  sql << " RETURNING #{insert.returning}" if insert.returning
  sql
end

def build_statement_pool
  StatementPool.new(self.class.type_cast_config_to_integer(@config[:statement_limit]))
end

def change_column(table_name, column_name, type, **options) # :nodoc:
  alter_table(table_name) do |definition|
    definition.change_column(column_name, type, **options)
  end
end

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

def change_column_null(table_name, column_name, null, default = nil) # :nodoc:
  validate_change_column_null_argument!(null)
  unless null || default.nil?
    internal_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 check_all_foreign_keys_valid! # :nodoc:
  sql = "PRAGMA foreign_key_check"
  result = execute(sql)
  unless result.blank?
    tables = result.map { |row| row["table"] }
    raise ActiveRecord::StatementInvalid.new("Foreign key violations found: #{tables.join(", ")}", sql: sql, connection_pool: @pool)
  end
end

def check_version # :nodoc:
  if database_version < "3.8.0"
    raise "Your version of SQLite (#{database_version}) is too old. Active Record supports SQLite >= 3.8."
  end
end

def configure_connection
  if @config[:timeout] && @config[:retries]
    raise ArgumentError, "Cannot specify both timeout and retries arguments"
  elsif @config[:timeout]
    timeout = self.class.type_cast_config_to_integer(@config[:timeout])
    raise TypeError, "timeout must be integer, not #{timeout}" unless timeout.is_a?(Integer)
    @raw_connection.busy_handler_timeout = timeout
  elsif @config[:retries]
    ActiveRecord.deprecator.warn(<<~MSG)
      The retries option is deprecated and will be removed in Rails 8.1. Use timeout instead.
    MSG
    retries = self.class.type_cast_config_to_integer(@config[:retries])
    raw_connection.busy_handler { |count| count <= retries }
  end
  super
  pragmas = @config.fetch(:pragmas, {}).stringify_keys
  DEFAULT_PRAGMAS.merge(pragmas).each do |pragma, value|
    if ::SQLite3::Pragmas.method_defined?("#{pragma}=")
      @raw_connection.public_send("#{pragma}=", value)
    else
      warn "Unknown SQLite pragma: #{pragma}"
    end
  end
end

def connect
  @raw_connection = self.class.new_client(@connection_parameters)
rescue ConnectionNotEstablished => ex
  raise ex.set_pool(@pool)
end

def connected?
  !(@raw_connection.nil? || @raw_connection.closed?)
end

def copy_table(from, to, options = {})
  from_primary_key = primary_key(from)
  options[:id] = false
  create_table(to, **options) do |definition|
    @definition = definition
    if from_primary_key.is_a?(Array)
      @definition.primary_keys from_primary_key
    end
    columns(from).each do |column|
      column_name = options[:rename] ?
        (options[:rename][column.name] ||
         options[:rename][column.name.to_sym] ||
         column.name) : column.name
      column_options = {
        limit: column.limit,
        precision: column.precision,
        scale: column.scale,
        null: column.null,
        collation: column.collation,
        primary_key: column_name == from_primary_key
      }
      if column.virtual?
        column_options[:as] = column.default_function
        column_options[:stored] = column.virtual_stored?
        column_options[:type] = column.type
      elsif column.has_default?
        type = lookup_cast_type_from_column(column)
        default = type.deserialize(column.default)
        default = -> { column.default_function } if default.nil?
        unless column.auto_increment?
          column_options[:default] = default
        end
      end
      column_type = column.virtual? ? :virtual : (column.bigint? ? :bigint : column.type)
      @definition.column(column_name, column_type, **column_options)
    end
    yield @definition if block_given?
  end
  copy_table_indexes(from, to, options[:rename] || {})
  columns_to_copy = @definition.columns.reject { |col| col.options.key?(:as) }.map(&:name)
  copy_table_contents(from, to,
    columns_to_copy,
    options[:rename] || {})
end

def copy_table_contents(from, to, columns, rename = {})
  column_mappings = Hash[columns.map { |name| [name, name] }]
  rename.each { |a| column_mappings[a.last] = a.first }
  from_columns = columns(from).collect(&:name)
  columns = columns.find_all { |col| from_columns.include?(column_mappings[col]) }
  from_columns_to_copy = columns.map { |col| column_mappings[col] }
  quoted_columns = columns.map { |col| quote_column_name(col) } * ","
  quoted_from_columns = from_columns_to_copy.map { |col| quote_column_name(col) } * ","
  internal_exec_query("INSERT INTO #{quote_table_name(to)} (#{quoted_columns})
             SELECT #{quoted_from_columns} FROM #{quote_table_name(from)}")
end

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

def create_virtual_table(table_name, module_name, values)
  exec_query "CREATE VIRTUAL TABLE IF NOT EXISTS #{table_name} USING #{module_name} (#{values.join(", ")})"
end

def database_exists?
  @config[:database] == ":memory:" || File.exist?(@config[:database].to_s)
end

def dbconsole(config, options = {})
  args = []
  args << "-#{options[:mode]}" if options[:mode]
  args << "-header" if options[:header]
  args << File.expand_path(config.database, Rails.respond_to?(:root) ? Rails.root : nil)
  find_cmd_and_exec(ActiveRecord.database_cli[:sqlite], *args)
end

def disable_referential_integrity # :nodoc:
  old_foreign_keys = query_value("PRAGMA foreign_keys")
  old_defer_foreign_keys = query_value("PRAGMA defer_foreign_keys")
  begin
    execute("PRAGMA defer_foreign_keys = ON")
    execute("PRAGMA foreign_keys = OFF")
    yield
  ensure
    execute("PRAGMA defer_foreign_keys = #{old_defer_foreign_keys}")
    execute("PRAGMA foreign_keys = #{old_foreign_keys}")
  end
end

def disconnect!
  super
  @raw_connection&.close rescue nil
  @raw_connection = nil
end

def drop_virtual_table(table_name, module_name, values, **options)
  drop_table(table_name)
end

def encoding
  any_raw_connection.encoding.to_s
end

def extract_default_function(default_value, default)
  default if has_default_function?(default_value, default)
end

def extract_value_from_default(default)
  case default
  when /^null$/i
    nil
  # Quoted types
  when /^'([^|]*)'$/m
    $1.gsub("''", "'")
  # Quoted types
  when /^"([^|]*)"$/m
    $1.gsub('""', '"')
  # Numeric types
  when /\A-?\d+(\.\d*)?\z/
    $&
  # Binary columns
  when /x'(.*)'/
    [ $1 ].pack("H*")
  else
    # Anything else is blank or some function
    # and we can't know the value of that, so return nil.
    nil
  end
end

def foreign_keys(table_name)
  # SQLite returns 1 row for each column of composite foreign keys.
  fk_info = internal_exec_query("PRAGMA foreign_key_list(#{quote(table_name)})", "SCHEMA")
  # Deferred or immediate foreign keys can only be seen in the CREATE TABLE sql
  fk_defs = table_structure_sql(table_name)
              .select do |column_string|
                column_string.start_with?("CONSTRAINT") &&
                column_string.include?("FOREIGN KEY")
              end
              .to_h do |fk_string|
                _, from, table, to = fk_string.match(FK_REGEX).to_a
                _, mode = fk_string.match(DEFERRABLE_REGEX).to_a
                deferred = mode&.downcase&.to_sym || false
                [[table, from, to], deferred]
              end
  grouped_fk = fk_info.group_by { |row| row["id"] }.values.each { |group| group.sort_by! { |row| row["seq"] } }
  grouped_fk.map do |group|
    row = group.first
    options = {
      on_delete: extract_foreign_key_action(row["on_delete"]),
      on_update: extract_foreign_key_action(row["on_update"]),
      deferrable: fk_defs[[row["table"], row["from"], row["to"]]]
    }
    if group.one?
      options[:column] = row["from"]
      options[:primary_key] = row["to"]
    else
      options[:column] = group.map { |row| row["from"] }
      options[:primary_key] = group.map { |row| row["to"] }
    end
    ForeignKeyDefinition.new(table_name, row["table"], options)
  end
end

def get_database_version # :nodoc:
  SQLite3Adapter::Version.new(query_value("SELECT sqlite_version(*)", "SCHEMA"))
end

def has_default_function?(default_value, default)
  !default_value && %r{\w+\(.*\)|CURRENT_TIME|CURRENT_DATE|CURRENT_TIMESTAMP|\|\|}.match?(default)
end

def initialize(...)
  super
  @memory_database = false
  case @config[:database].to_s
  when ""
    raise ArgumentError, "No database file specified. Missing argument: database"
  when ":memory:"
    @memory_database = true
  when /\Afile:/
  else
    # Otherwise we have a path relative to Rails.root
    @config[:database] = File.expand_path(@config[:database], Rails.root) if defined?(Rails.root)
    dirname = File.dirname(@config[:database])
    unless File.directory?(dirname)
      begin
        FileUtils.mkdir_p(dirname)
      rescue SystemCallError
        raise ActiveRecord::NoDatabaseError.new(connection_pool: @pool)
      end
    end
  end
  @last_affected_rows = nil
  @previous_read_uncommitted = nil
  @config[:strict] = ConnectionAdapters::SQLite3Adapter.strict_strings_by_default unless @config.key?(:strict)
  @connection_parameters = @config.merge(
    database: @config[:database].to_s,
    results_as_hash: true,
    default_transaction_mode: :immediate,
  )
end

def initialize_type_map(m)
  super
  register_class_with_limit m, %r(int)i, SQLite3Integer
end

def invalid_alter_table_type?(type, options)
  type == :primary_key || options[:primary_key] ||
    options[:null] == false && options[:default].nil? ||
    (type == :virtual && options[:stored])
end

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

def native_database_types # :nodoc:
  NATIVE_DATABASE_TYPES
end

def new_client(config)
  ::SQLite3::Database.new(config[:database].to_s, config)
rescue Errno::ENOENT => error
  if error.message.include?("No such file or directory")
    raise ActiveRecord::NoDatabaseError
  else
    raise
  end
end

def primary_keys(table_name) # :nodoc:
  pks = table_structure(table_name).select { |f| f["pk"] > 0 }
  pks.sort_by { |f| f["pk"] }.map { |f| f["name"] }
end

def reconnect
  if active?
    @raw_connection.rollback rescue nil
  else
    connect
  end
end

def remove_column(table_name, column_name, type = nil, **options) # :nodoc:
  alter_table(table_name) do |definition|
    definition.remove_column column_name
    definition.foreign_keys.delete_if { |fk| fk.column == column_name.to_s }
  end
end

def remove_columns(table_name, *column_names, type: nil, **options) # :nodoc:
  alter_table(table_name) do |definition|
    column_names.each do |column_name|
      definition.remove_column column_name
    end
    column_names = column_names.map(&:to_s)
    definition.foreign_keys.delete_if { |fk| column_names.include?(fk.column) }
  end
end

def remove_index(table_name, column_name = nil, **options) # :nodoc:
  return if options[:if_exists] && !index_exists?(table_name, column_name, **options)
  index_name = index_name_for_remove(table_name, column_name, options)
  exec_query "DROP INDEX #{quote_column_name(index_name)}"
end

def rename_column(table_name, column_name, new_column_name) # :nodoc:
  column = column_for(table_name, column_name)
  alter_table(table_name, rename: { column.name => new_column_name.to_s })
  rename_column_indexes(table_name, column.name, new_column_name)
end

def rename_table(table_name, new_name, **options)
  validate_table_length!(new_name) unless options[:_uses_legacy_table_name]
  schema_cache.clear_data_source_cache!(table_name.to_s)
  schema_cache.clear_data_source_cache!(new_name.to_s)
  exec_query "ALTER TABLE #{quote_table_name(table_name)} RENAME TO #{quote_table_name(new_name)}"
  rename_table_indexes(table_name, new_name, **options)
end

def requires_reloading?
  true
end

def shared_cache? # :nodoc:
  @config.fetch(:flags, 0).anybits?(::SQLite3::Constants::Open::SHAREDCACHE)
end

def supports_check_constraints?
  true
end

def supports_common_table_expressions?
  database_version >= "3.8.3"
end

def supports_concurrent_connections?
  !@memory_database
end

def supports_datetime_with_precision?
  true
end

def supports_ddl_transactions?
  true
end

def supports_deferrable_constraints?
  true
end

def supports_explain?
  true
end

def supports_expression_index?
  database_version >= "3.9.0"
end

def supports_foreign_keys?
  true
end

def supports_index_sort_order?
  true
end

def supports_insert_on_conflict?
  database_version >= "3.24.0"
end

def supports_insert_returning?
  database_version >= "3.35.0"
end

def supports_json?
  true
end

def supports_lazy_transactions?
  true
end

def supports_partial_index?
  true
end

def supports_savepoints?
  true
end

def supports_transaction_isolation?
  true
end

def supports_views?
  true
end

def supports_virtual_columns?
  database_version >= "3.31.0"
end

def table_info(table_name)
  if supports_virtual_columns?
    internal_exec_query("PRAGMA table_xinfo(#{quote_table_name(table_name)})", "SCHEMA")
  else
    internal_exec_query("PRAGMA table_info(#{quote_table_name(table_name)})", "SCHEMA")
  end
end

def table_structure(table_name)
  structure = table_info(table_name)
  raise ActiveRecord::StatementInvalid.new("Could not find table '#{table_name}'", connection_pool: @pool) if structure.empty?
  table_structure_with_collation(table_name, structure)
end

def table_structure_sql(table_name, column_names = nil)
  unless column_names
    column_info = table_info(table_name)
    column_names = column_info.map { |column| column["name"] }
  end
  sql = <<~SQL
    SELECT sql FROM
      (SELECT * FROM sqlite_master UNION ALL
       SELECT * FROM sqlite_temp_master)
    WHERE type = 'table' AND name = #{quote(table_name)}
  SQL
  # Result will have following sample string
  # CREATE TABLE "users" ("id" INTEGER PRIMARY KEY AUTOINCREMENT NOT NULL,
  #                       "password_digest" varchar COLLATE "NOCASE",
  #                       "o_id" integer,
  #                       CONSTRAINT "fk_rails_78146ddd2e" FOREIGN KEY ("o_id") REFERENCES "os" ("id"));
  result = query_value(sql, "SCHEMA")
  return [] unless result
  # Splitting with left parentheses and discarding the first part will return all
  # columns separated with comma(,).
  result.partition(UNQUOTED_OPEN_PARENS_REGEX)
        .last
        .sub(FINAL_CLOSE_PARENS_REGEX, "")
        # column definitions can have a comma in them, so split on commas followed
        # by a space and a column name in quotes or followed by the keyword CONSTRAINT
        .split(/,(?=\s(?:CONSTRAINT|"(?:#{Regexp.union(column_names).source})"))/i)
        .map(&:strip)
end

def table_structure_with_collation(table_name, basic_structure)
  collation_hash = {}
  auto_increments = {}
  generated_columns = {}
  column_strings = table_structure_sql(table_name, basic_structure.map { |column| column["name"] })
  if column_strings.any?
    column_strings.each do |column_string|
      # This regex will match the column name and collation type and will save
      # the value in $1 and $2 respectively.
      collation_hash[$1] = $2 if COLLATE_REGEX =~ column_string
      auto_increments[$1] = true if PRIMARY_KEY_AUTOINCREMENT_REGEX =~ column_string
      generated_columns[$1] = $2 if GENERATED_ALWAYS_AS_REGEX =~ column_string
    end
    basic_structure.map do |column|
      column_name = column["name"]
      if collation_hash.has_key? column_name
        column["collation"] = collation_hash[column_name]
      end
      if auto_increments.has_key?(column_name)
        column["auto_increment"] = true
      end
      if generated_columns.has_key?(column_name)
        column["dflt_value"] = generated_columns[column_name]
      end
      column
    end
  else
    basic_structure.to_a
  end
end

def translate_exception(exception, message:, sql:, binds:)
  # 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
  if exception.message.match?(/(column(s)? .* (is|are) not unique|UNIQUE constraint failed: .*)/i)
    RecordNotUnique.new(message, sql: sql, binds: binds, connection_pool: @pool)
  elsif exception.message.match?(/(.* may not be NULL|NOT NULL constraint failed: .*)/i)
    NotNullViolation.new(message, sql: sql, binds: binds, connection_pool: @pool)
  elsif exception.message.match?(/FOREIGN KEY constraint failed/i)
    InvalidForeignKey.new(message, sql: sql, binds: binds, connection_pool: @pool)
  elsif exception.message.match?(/called on a closed database/i)
    ConnectionNotEstablished.new(exception, connection_pool: @pool)
  elsif exception.is_a?(::SQLite3::BusyException)
    StatementTimeout.new(message, sql: sql, binds: binds, connection_pool: @pool)
  else
    super
  end
end

def virtual_tables
  query = <<~SQL
    SELECT name, sql FROM sqlite_master WHERE sql LIKE 'CREATE VIRTUAL %';
  SQL
  exec_query(query, "SCHEMA").cast_values.each_with_object({}) do |row, memo|
    table_name, sql = row[0], row[1]
    _, module_name, arguments = sql.match(VIRTUAL_TABLE_REGEX).to_a
    memo[table_name] = [module_name, arguments]
  end.to_a
end