require 'rupy/python'
require 'rupy/macros'


module Rupy

    #Raised when an error occurs in the Python interpreter.
    class PythonError < Exception

        #@param [String] typeName the class name of the Python error
        #@param [String] msg the message attached to the Python error
        def initialize(typeName, msg)
            @type = typeName
            super([typeName, msg].join(': '))
        end

        #This method should be called when an error has occured in the
        #Python interpreter. This acts as factory function for PythonError
        #objects. The function fetchs calls {fetch} to get the error
        #information from the Python interpreter and uses this to build
        #a PythonError object. It then calls {clear} to clear the error
        #flag of the python interpreter
        #@return [PythonError] an error enscapsulating the Python error
        def self.handle_error
            rbType, rbValue, rbTraceback = fetch()
            p rbTraceback

            if not rbValue.null?
                msg = rbValue.getAttr("__str__").callObject PyObject.buildArgTuple
                msg = msg.rubify
            else
                msg = nil
            end

            #Decrease the reference count. This will happen anyway when they go
            #out of scope but might as well.
            rbValue.xDecref
            rbTraceback.xDecref
            pyName = rbType.getAttr("__name__")

            rbType.xDecref
            rbName = pyName.rubify
            pyName.xDecref

            PythonError.clear

            PythonError.new(rbName, msg)
        end

        #A wrapper to the Python C API PyErr_Fetch function.
        #@return [Array<PyObject>] an array containing three {PyObject} instances.
        #   representing the Type, Value, and stacktrace of the python
        #   error respectively.
        def self.fetch
            typePointer = FFI::MemoryPointer.new :pointer
            valuePointer = FFI::MemoryPointer.new :pointer
            tracebackPointer = FFI::MemoryPointer.new :pointer

            Python.PyErr_Fetch typePointer, valuePointer, tracebackPointer

            rbType = PyObject.new typePointer.read_pointer
            rbValue = PyObject.new valuePointer.read_pointer
            rbTraceback = PyObject.new tracebackPointer.read_pointer
            [rbType, rbValue, rbTraceback]
        end

        #Determines whether an error has occured in the python interpreter.
        def self.error?
            !Python.PyErr_Occurred.null?
        end

        #Resets the Python interpreter error flag
        #@return [void]
        def self.clear
            Python.PyErr_Clear
        end

    end
end