module ActiveRecord
  # = Active Record Errors
  #
  # Generic Active Record exception class.
  class ActiveRecordError < StandardError
  end

  # Raised when the single-table inheritance mechanism fails to locate the subclass
  # (for example due to improper usage of column that
  # {ActiveRecord::Base.inheritance_column}[rdoc-ref:ModelSchema::ClassMethods#inheritance_column]
  # points to).
  class SubclassNotFound < ActiveRecordError
  end

  # Raised when an object assigned to an association has an incorrect type.
  #
  #   class Ticket < ActiveRecord::Base
  #     has_many :patches
  #   end
  #
  #   class Patch < ActiveRecord::Base
  #     belongs_to :ticket
  #   end
  #
  #   # Comments are not patches, this assignment raises AssociationTypeMismatch.
  #   @ticket.patches << Comment.new(content: "Please attach tests to your patch.")
  class AssociationTypeMismatch < ActiveRecordError
  end

  # Raised when unserialized object's type mismatches one specified for serializable field.
  class SerializationTypeMismatch < ActiveRecordError
  end

  # Raised when adapter not specified on connection (or configuration file
  # +config/database.yml+ misses adapter field).
  class AdapterNotSpecified < ActiveRecordError
  end

  # Raised when Active Record cannot find database adapter specified in
  # +config/database.yml+ or programmatically.
  class AdapterNotFound < ActiveRecordError
  end

  # Raised when connection to the database could not been established (for example when
  # {ActiveRecord::Base.connection=}[rdoc-ref:ConnectionHandling#connection]
  # is given a +nil+ object).
  class ConnectionNotEstablished < ActiveRecordError
  end

  # Raised when Active Record cannot find a record by given id or set of ids.
  class RecordNotFound < ActiveRecordError
    attr_reader :model, :primary_key, :id

    def initialize(message = nil, model = nil, primary_key = nil, id = nil)
      @primary_key = primary_key
      @model = model
      @id = id

      super(message)
    end
  end

  # Raised by {ActiveRecord::Base#save!}[rdoc-ref:Persistence#save!] and
  # {ActiveRecord::Base.create!}[rdoc-ref:Persistence::ClassMethods#create!]
  # methods when a record is invalid and can not be saved.
  class RecordNotSaved < ActiveRecordError
    attr_reader :record

    def initialize(message = nil, record = nil)
      @record = record
      super(message)
    end
  end

  # Raised by {ActiveRecord::Base#destroy!}[rdoc-ref:Persistence#destroy!]
  # when a call to {#destroy}[rdoc-ref:Persistence#destroy!]
  # would return false.
  #
  #   begin
  #     complex_operation_that_internally_calls_destroy!
  #   rescue ActiveRecord::RecordNotDestroyed => invalid
  #     puts invalid.record.errors
  #   end
  #
  class RecordNotDestroyed < ActiveRecordError
    attr_reader :record

    def initialize(message = nil, record = nil)
      @record = record
      super(message)
    end
  end

  # Superclass for all database execution errors.
  #
  # Wraps the underlying database error as +cause+.
  class StatementInvalid < ActiveRecordError
    def initialize(message = nil, original_exception = nil)
      if original_exception
        ActiveSupport::Deprecation.warn("Passing #original_exception is deprecated and has no effect. " \
                                        "Exceptions will automatically capture the original exception.", caller)
      end

      super(message || $!.try(:message))
    end

    def original_exception
      ActiveSupport::Deprecation.warn("#original_exception is deprecated. Use #cause instead.", caller)
      cause
    end
  end

  # Defunct wrapper class kept for compatibility.
  # StatementInvalid wraps the original exception now.
  class WrappedDatabaseException < StatementInvalid
  end

  # Raised when a record cannot be inserted because it would violate a uniqueness constraint.
  class RecordNotUnique < WrappedDatabaseException
  end

  # Raised when a record cannot be inserted or updated because it references a non-existent record.
  class InvalidForeignKey < WrappedDatabaseException
  end

  # Raised when a foreign key constraint cannot be added because the column type does not match the referenced column type.
  class MismatchedForeignKey < StatementInvalid
    def initialize(adapter = nil, message: nil, table: nil, foreign_key: nil, target_table: nil, primary_key: nil)
      @adapter = adapter
      if table
        msg = <<-EOM.strip_heredoc
          Column `#{foreign_key}` on table `#{table}` has a type of `#{column_type(table, foreign_key)}`.
          This does not match column `#{primary_key}` on `#{target_table}`, which has type `#{column_type(target_table, primary_key)}`.
          To resolve this issue, change the type of the `#{foreign_key}` column on `#{table}` to be :integer. (For example `t.integer #{foreign_key}`).
        EOM
      else
        msg = <<-EOM
          There is a mismatch between the foreign key and primary key column types.
          Verify that the foreign key column type and the primary key of the associated table match types.
        EOM
      end
      if message
        msg << "\nOriginal message: #{message}"
      end
      super(msg)
    end

    private
      def column_type(table, column)
        @adapter.columns(table).detect { |c| c.name == column }.sql_type
      end
  end

  # Raised when a record cannot be inserted or updated because it would violate a not null constraint.
  class NotNullViolation < StatementInvalid
  end

  # Raised when a record cannot be inserted or updated because a value too long for a column type.
  class ValueTooLong < StatementInvalid
  end

  # Raised when number of bind variables in statement given to +:condition+ key
  # (for example, when using {ActiveRecord::Base.find}[rdoc-ref:FinderMethods#find] method)
  # does not match number of expected values supplied.
  #
  # For example, when there are two placeholders with only one value supplied:
  #
  #   Location.where("lat = ? AND lng = ?", 53.7362)
  class PreparedStatementInvalid < ActiveRecordError
  end

  # Raised when a given database does not exist.
  class NoDatabaseError < StatementInvalid
  end

  # Raised when Postgres returns 'cached plan must not change result type' and
  # we cannot retry gracefully (e.g. inside a transaction)
  class PreparedStatementCacheExpired < StatementInvalid
  end

  # Raised on attempt to save stale record. Record is stale when it's being saved in another query after
  # instantiation, for example, when two users edit the same wiki page and one starts editing and saves
  # the page before the other.
  #
  # Read more about optimistic locking in ActiveRecord::Locking module
  # documentation.
  class StaleObjectError < ActiveRecordError
    attr_reader :record, :attempted_action

    def initialize(record = nil, attempted_action = nil)
      if record && attempted_action
        @record = record
        @attempted_action = attempted_action
        super("Attempted to #{attempted_action} a stale object: #{record.class.name}.")
      else
        super("Stale object error.")
      end
    end
  end

  # Raised when association is being configured improperly or user tries to use
  # offset and limit together with
  # {ActiveRecord::Base.has_many}[rdoc-ref:Associations::ClassMethods#has_many] or
  # {ActiveRecord::Base.has_and_belongs_to_many}[rdoc-ref:Associations::ClassMethods#has_and_belongs_to_many]
  # associations.
  class ConfigurationError < ActiveRecordError
  end

  # Raised on attempt to update record that is instantiated as read only.
  class ReadOnlyRecord < ActiveRecordError
  end

  # {ActiveRecord::Base.transaction}[rdoc-ref:Transactions::ClassMethods#transaction]
  # uses this exception to distinguish a deliberate rollback from other exceptional situations.
  # Normally, raising an exception will cause the
  # {.transaction}[rdoc-ref:Transactions::ClassMethods#transaction] method to rollback
  # the database transaction *and* pass on the exception. But if you raise an
  # ActiveRecord::Rollback exception, then the database transaction will be rolled back,
  # without passing on the exception.
  #
  # For example, you could do this in your controller to rollback a transaction:
  #
  #   class BooksController < ActionController::Base
  #     def create
  #       Book.transaction do
  #         book = Book.new(params[:book])
  #         book.save!
  #         if today_is_friday?
  #           # The system must fail on Friday so that our support department
  #           # won't be out of job. We silently rollback this transaction
  #           # without telling the user.
  #           raise ActiveRecord::Rollback, "Call tech support!"
  #         end
  #       end
  #       # ActiveRecord::Rollback is the only exception that won't be passed on
  #       # by ActiveRecord::Base.transaction, so this line will still be reached
  #       # even on Friday.
  #       redirect_to root_url
  #     end
  #   end
  class Rollback < ActiveRecordError
  end

  # Raised when attribute has a name reserved by Active Record (when attribute
  # has name of one of Active Record instance methods).
  class DangerousAttributeError < ActiveRecordError
  end

  # Raised when unknown attributes are supplied via mass assignment.
  UnknownAttributeError = ActiveModel::UnknownAttributeError

  # Raised when an error occurred while doing a mass assignment to an attribute through the
  # {ActiveRecord::Base#attributes=}[rdoc-ref:AttributeAssignment#attributes=] method.
  # The exception has an +attribute+ property that is the name of the offending attribute.
  class AttributeAssignmentError < ActiveRecordError
    attr_reader :exception, :attribute

    def initialize(message = nil, exception = nil, attribute = nil)
      super(message)
      @exception = exception
      @attribute = attribute
    end
  end

  # Raised when there are multiple errors while doing a mass assignment through the
  # {ActiveRecord::Base#attributes=}[rdoc-ref:AttributeAssignment#attributes=]
  # method. The exception has an +errors+ property that contains an array of AttributeAssignmentError
  # objects, each corresponding to the error while assigning to an attribute.
  class MultiparameterAssignmentErrors < ActiveRecordError
    attr_reader :errors

    def initialize(errors = nil)
      @errors = errors
    end
  end

  # Raised when a primary key is needed, but not specified in the schema or model.
  class UnknownPrimaryKey < ActiveRecordError
    attr_reader :model

    def initialize(model = nil, description = nil)
      if model
        message = "Unknown primary key for table #{model.table_name} in model #{model}."
        message += "\n#{description}" if description
        @model = model
        super(message)
      else
        super("Unknown primary key.")
      end
    end
  end

  # Raised when a relation cannot be mutated because it's already loaded.
  #
  #   class Task < ActiveRecord::Base
  #   end
  #
  #   relation = Task.all
  #   relation.loaded? # => true
  #
  #   # Methods which try to mutate a loaded relation fail.
  #   relation.where!(title: 'TODO')  # => ActiveRecord::ImmutableRelation
  #   relation.limit!(5)              # => ActiveRecord::ImmutableRelation
  class ImmutableRelation < ActiveRecordError
  end

  # TransactionIsolationError will be raised under the following conditions:
  #
  # * The adapter does not support setting the isolation level
  # * You are joining an existing open transaction
  # * You are creating a nested (savepoint) transaction
  #
  # The mysql2 and postgresql adapters support setting the transaction isolation level.
  class TransactionIsolationError < ActiveRecordError
  end

  # TransactionRollbackError will be raised when a transaction is rolled
  # back by the database due to a serialization failure or a deadlock.
  #
  # See the following:
  #
  # * http://www.postgresql.org/docs/current/static/transaction-iso.html
  # * https://dev.mysql.com/doc/refman/5.7/en/error-messages-server.html#error_er_lock_deadlock
  class TransactionRollbackError < StatementInvalid
  end

  # SerializationFailure will be raised when a transaction is rolled
  # back by the database due to a serialization failure.
  class SerializationFailure < TransactionRollbackError
  end

  # Deadlocked will be raised when a transaction is rolled
  # back by the database when a deadlock is encountered.
  class Deadlocked < TransactionRollbackError
  end

  # IrreversibleOrderError is raised when a relation's order is too complex for
  # +reverse_order+ to automatically reverse.
  class IrreversibleOrderError < ActiveRecordError
  end
end