# frozen_string_literal: true

require "active_support/core_ext/string/filters"

module ActiveRecord
  module ConnectionAdapters
    extend ActiveSupport::Autoload

    @adapters = {}

    class << self
      # Registers a custom database adapter.
      #
      # Can also be used to define aliases.
      #
      # == Example
      #
      #   ActiveRecord::ConnectionAdapters.register("megadb", "MegaDB::ActiveRecordAdapter", "mega_db/active_record_adapter")
      #
      #   ActiveRecord::ConnectionAdapters.register("mysql", "ActiveRecord::ConnectionAdapters::TrilogyAdapter", "active_record/connection_adapters/trilogy_adapter")
      #
      def register(name, class_name, path = class_name.underscore)
        @adapters[name.to_s] = [class_name, path]
      end

      def resolve(adapter_name) # :nodoc:
        # Require the adapter itself and give useful feedback about
        #   1. Missing adapter gems.
        #   2. Incorrectly registered adapters.
        #   3. Adapter gems' missing dependencies.
        class_name, path_to_adapter = @adapters[adapter_name.to_s]

        unless class_name
          # To provide better error messages for adapters expecting the pre-7.2 adapter registration API, we attempt
          # to load the adapter file from the old location which was required by convention, and then raise an error
          # describing how to upgrade the adapter to the new API.
          legacy_adapter_path = "active_record/connection_adapters/#{adapter_name}_adapter"
          legacy_adapter_connection_method_name = "#{adapter_name}_connection".to_sym

          begin
            require legacy_adapter_path
            # If we reach here it means we found the found a file that may be the legacy adapter and should raise.
            if ActiveRecord::ConnectionHandling.method_defined?(legacy_adapter_connection_method_name)
              # If we find the connection method then we care certain it is a legacy adapter.
              deprecation_message = <<~MSG.squish
                Database configuration specifies '#{adapter_name}' adapter but that adapter has not been registered.
                Rails 7.2 has changed the way Active Record database adapters are loaded. The adapter needs to be
                updated to register itself rather than being loaded by convention.
                Ensure that the adapter in the Gemfile is at the latest version. If it is, then the adapter may need to
                be modified.
                See:
                https://api.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters.html#method-c-register
              MSG

              exception_message = <<~MSG.squish
                Database configuration specifies '#{adapter_name}' adapter but that adapter has not been registered.
                Ensure that the adapter in the Gemfile is at the latest version. If it is, then the adapter may need to
                be modified.
              MSG
            else
              # If we do not find the connection method we are much less certain it is a legacy adapter. Even though the
              # file exists in the location defined by convenntion, it does not necessarily mean that file is supposed
              # to define the adapter the legacy way. So raise an error that explains both possibilities.
              deprecation_message = <<~MSG.squish
                Database configuration specifies nonexistent '#{adapter_name}' adapter.
                Available adapters are: #{@adapters.keys.sort.join(", ")}.
                Ensure that the adapter is spelled correctly in config/database.yml and that you've added the necessary
                adapter gem to your Gemfile if it's not in the list of available adapters.
                Rails 7.2 has changed the way Active Record database adapters are loaded. Ensure that the adapter in
                the Gemfile is at the latest version. If it is up to date, the adapter may need to be modified.
                See:
                https://api.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters.html#method-c-register
              MSG

              exception_message = <<~MSG.squish
                Database configuration specifies nonexistent '#{adapter_name}' adapter.
                Available adapters are: #{@adapters.keys.sort.join(", ")}.
                Ensure that the adapter is spelled correctly in config/database.yml and that you've added the necessary
                adapter gem to your Gemfile and that it is at its latest version. If it is up to date, the adapter may
                need to be modified.
              MSG
            end

            ActiveRecord.deprecator.warn(deprecation_message)
            raise AdapterNotFound, exception_message
          rescue LoadError => error
            # The adapter was not found in the legacy location so fall through to the error handling for a missing adapter.
          end

          raise AdapterNotFound, <<~MSG.squish
            Database configuration specifies nonexistent '#{adapter_name}' adapter.
            Available adapters are: #{@adapters.keys.sort.join(", ")}.
            Ensure that the adapter is spelled correctly in config/database.yml and that you've added the necessary
            adapter gem to your Gemfile if it's not in the list of available adapters.
          MSG
        end

        unless Object.const_defined?(class_name)
          begin
            require path_to_adapter
          rescue LoadError => error
            # We couldn't require the adapter itself.
            if error.path == path_to_adapter
              # We can assume here that a non-builtin adapter was specified and the path
              # registered by the adapter gem is incorrect.
              raise LoadError, "Error loading the '#{adapter_name}' Active Record adapter. Ensure that the path registered by the adapter gem is correct. #{error.message}", error.backtrace
            else
              # Bubbled up from the adapter require. Prefix the exception message
              # with some guidance about how to address it and reraise.
              raise LoadError, "Error loading the '#{adapter_name}' Active Record adapter. Missing a gem it depends on? #{error.message}", error.backtrace
            end
          end
        end

        begin
          Object.const_get(class_name)
        rescue NameError => error
          raise AdapterNotFound, "Could not load the #{class_name} Active Record adapter (#{error.message})."
        end
      end
    end

    register "sqlite3", "ActiveRecord::ConnectionAdapters::SQLite3Adapter", "active_record/connection_adapters/sqlite3_adapter"
    register "mysql2", "ActiveRecord::ConnectionAdapters::Mysql2Adapter", "active_record/connection_adapters/mysql2_adapter"
    register "trilogy", "ActiveRecord::ConnectionAdapters::TrilogyAdapter", "active_record/connection_adapters/trilogy_adapter"
    register "postgresql", "ActiveRecord::ConnectionAdapters::PostgreSQLAdapter", "active_record/connection_adapters/postgresql_adapter"

    eager_autoload do
      autoload :AbstractAdapter
    end

    autoload :Column
    autoload :PoolConfig
    autoload :PoolManager
    autoload :SchemaCache
    autoload :BoundSchemaReflection, "active_record/connection_adapters/schema_cache"
    autoload :SchemaReflection, "active_record/connection_adapters/schema_cache"
    autoload :Deduplicable

    autoload_at "active_record/connection_adapters/abstract/schema_definitions" do
      autoload :IndexDefinition
      autoload :ColumnDefinition
      autoload :ChangeColumnDefinition
      autoload :ChangeColumnDefaultDefinition
      autoload :ForeignKeyDefinition
      autoload :CheckConstraintDefinition
      autoload :TableDefinition
      autoload :Table
      autoload :AlterTable
      autoload :ReferenceDefinition
    end

    autoload_under "abstract" do
      autoload :SchemaStatements
      autoload :DatabaseStatements
      autoload :DatabaseLimits
      autoload :Quoting
      autoload :ConnectionHandler
      autoload :QueryCache
      autoload :Savepoints
    end

    autoload_at "active_record/connection_adapters/abstract/connection_pool" do
      autoload :ConnectionPool
      autoload :NullPool
    end

    autoload_at "active_record/connection_adapters/abstract/transaction" do
      autoload :TransactionManager
      autoload :NullTransaction
      autoload :RealTransaction
      autoload :SavepointTransaction
      autoload :TransactionState
    end
  end
end