import os
import sys
import re

from . import catalog
from . import build_tools
from . import converters
from . import base_spec

class ext_function_from_specs(object):
    def __init__(self,name,code_block,arg_specs):
        self.name = name
        self.arg_specs = base_spec.arg_spec_list(arg_specs)
        self.code_block = code_block
        self.compiler = ''
        self.customize = base_info.custom_info()

    def header_code(self):
        pass

    def function_declaration_code(self):
        code  = 'static PyObject* %s(PyObject*self, PyObject* args,' \
                ' PyObject* kywds)\n{\n'
        return code % self.name

    def template_declaration_code(self):
        code = 'template<class T>\n' \
               'static PyObject* %s(PyObject*self, PyObject* args,' \
               ' PyObject* kywds)\n{\n'
        return code % self.name

    #def cpp_function_declaration_code(self):
    #    pass
    #def cpp_function_call_code(self):
    #s    pass

    def parse_tuple_code(self):
        """ Create code block for PyArg_ParseTuple.  Variable declarations
            for all PyObjects are done also.

            This code got a lot uglier when I added local_dict...
        """

        declare_return = 'py::object return_val;\n' \
                         'int exception_occurred = 0;\n' \
                         'PyObject *py_local_dict = NULL;\n'
        arg_string_list = self.arg_specs.variable_as_strings() + ['"local_dict"']
        arg_strings = ','.join(arg_string_list)
        if arg_strings: arg_strings += ','
        declare_kwlist = 'static const char *kwlist[] = {%s NULL};\n' % \
                         arg_strings

        py_objects = ', '.join(self.arg_specs.py_pointers())
        init_flags = ', '.join(self.arg_specs.init_flags())
        init_flags_init = '= '.join(self.arg_specs.init_flags())
        py_vars = ' = '.join(self.arg_specs.py_variables())
        if py_objects:
            declare_py_objects  = 'PyObject ' + py_objects +';\n'
            declare_py_objects += 'int '+ init_flags + ';\n'
            init_values  = py_vars + ' = NULL;\n'
            init_values += init_flags_init + ' = 0;\n\n'
        else:
            declare_py_objects = ''
            init_values = ''

        #Each variable is in charge of its own cleanup now.
        #cnt = len(arg_list)
        #declare_cleanup = "blitz::TinyVector<PyObject*,%d> clean_up(0);\n" % cnt

        ref_string = ', '.join(self.arg_specs.py_references())
        if ref_string:
            ref_string += ', &py_local_dict'
        else:
            ref_string = '&py_local_dict'

        format = "O"* len(self.arg_specs) + "|O" + ':' + self.name
        parse_tuple =  'if(!PyArg_ParseTupleAndKeywords(args,' \
                             'kywds,"%s",const_cast<char**>(kwlist),%s))\n' % \
                             (format,ref_string)
        parse_tuple += '   return NULL;\n'

        return   declare_return + declare_kwlist + declare_py_objects  \
               + init_values + parse_tuple

    def arg_declaration_code(self):
        arg_strings = []
        for arg in self.arg_specs:
            arg_strings.append(arg.declaration_code())
            arg_strings.append(arg.init_flag() +" = 1;\n")
        code = "".join(arg_strings)
        return code

    def arg_cleanup_code(self):
        arg_strings = []
        have_cleanup = [x for x in self.arg_specs if x.cleanup_code()]
        for arg in have_cleanup:
            code  = "if(%s)\n" % arg.init_flag()
            code += "{\n"
            code +=     indent(arg.cleanup_code(),4)
            code += "}\n"
            arg_strings.append(code)
        code = "".join(arg_strings)
        return code

    def arg_local_dict_code(self):
        arg_strings = []
        for arg in self.arg_specs:
            arg_strings.append(arg.local_dict_code())
        code = "".join(arg_strings)
        return code

    def function_code(self):
        decl_code = indent(self.arg_declaration_code(),4)
        cleanup_code = indent(self.arg_cleanup_code(),4)
        function_code = indent(self.code_block,4)
        local_dict_code = indent(self.arg_local_dict_code(),4)

        dict_code = "if(py_local_dict)                                  \n"   \
                    "{                                                  \n"   \
                    "    py::dict local_dict = py::dict(py_local_dict); \n" + \
                         local_dict_code                                    + \
                    "}                                                  \n"

        try_code =    "try                              \n"   \
                      "{                                \n" + \
                           decl_code                        + \
                      "    /*<function call here>*/     \n" + \
                           function_code                    + \
                           indent(dict_code,4)              + \
                      "\n}                                \n"
        catch_code =  "catch(...)                       \n"   \
                      "{                                \n" + \
                      "    return_val =  py::object();      \n"   \
                      "    exception_occurred = 1;       \n"   \
                      "}                                \n"

        return_code = "    /*cleanup code*/                     \n" + \
                           cleanup_code                             + \
                      '    if(!(PyObject*)return_val && !exception_occurred)\n'   \
                      '    {\n                                  \n'   \
                      '        return_val = Py_None;            \n'   \
                      '    }\n                                  \n'   \
                      '    return return_val.disown();           \n'           \
                      '}                                \n'

        all_code = self.function_declaration_code()         + \
                       indent(self.parse_tuple_code(),4)    + \
                       indent(try_code,4)                   + \
                       indent(catch_code,4)                 + \
                       return_code

        return all_code

    def python_function_definition_code(self):
        args = (self.name, self.name)
        function_decls = '{"%s",(PyCFunction)%s , METH_VARARGS|' \
                          'METH_KEYWORDS},\n' % args
        return function_decls

    def set_compiler(self,compiler):
        self.compiler = compiler
        for arg in self.arg_specs:
            arg.set_compiler(compiler)


class ext_function(ext_function_from_specs):
    def __init__(self,name,code_block, args, local_dict=None, global_dict=None,
                 auto_downcast=1, type_converters=None):

        call_frame = sys._getframe().f_back
        if local_dict is None:
            local_dict = call_frame.f_locals
        if global_dict is None:
            global_dict = call_frame.f_globals
        if type_converters is None:
            type_converters = converters.default
        arg_specs = assign_variable_types(args,local_dict, global_dict,
                                          auto_downcast, type_converters)
        ext_function_from_specs.__init__(self,name,code_block,arg_specs)


from . import base_info

class ext_module(object):
    def __init__(self,name,compiler=''):
        standard_info = converters.standard_info
        self.name = name
        self.functions = []
        self.compiler = compiler
        self.customize = base_info.custom_info()
        self._build_information = base_info.info_list(standard_info)

    def add_function(self,func):
        self.functions.append(func)
    def module_code(self):
        code = '\n'.join([
            """\
#ifdef __CPLUSPLUS__
extern "C" {
#endif
""",
            self.warning_code(),
            self.header_code(),
            self.support_code(),
            self.function_code(),
            self.python_function_definition_code(),
            self.module_init_code(),
            """\
#ifdef __CPLUSCPLUS__
}
#endif
"""
            ])
        return code

    def arg_specs(self):
        all_arg_specs = base_spec.arg_spec_list()
        for func in self.functions:
            all_arg_specs += func.arg_specs
        return all_arg_specs

    def build_information(self):
        info = self._build_information + [self.customize] + \
               self.arg_specs().build_information()
        for func in self.functions:
            info.append(func.customize)
        #redundant, but easiest place to make sure compiler is set
        for i in info:
            i.set_compiler(self.compiler)
        return info

    def get_headers(self):
        all_headers = self.build_information().headers()

        # blitz/array.h always needs to go before most other headers, so we
        # hack that here, but we need to ensure that Python.h is the very
        # first header included.  As indicated in

        # http://docs.python.org/api/includes.html

        # "Warning:  Since Python may define some pre-processor definitions which
        # affect the standard headers on some systems, you must include Python.h
        # before any standard headers are included. "

        # Since blitz/array.h pulls in system headers, we must massage this
        # list a bit so that the order is Python.h, blitz/array.h, ...

        if '"blitz/array.h"' in all_headers:
            all_headers.remove('"blitz/array.h"')
            # Insert blitz AFTER Python.h, which must remain the first header
            all_headers.insert(1,'"blitz/array.h"')
        return all_headers

    def warning_code(self):
        all_warnings = self.build_information().warnings()
        w=["#pragma warning(%s)\n" % x for x in all_warnings]
        return '#ifndef __GNUC__\n' + ''.join(w) + '\n#endif'

    def header_code(self):
        h = self.get_headers()
        h= ['#include ' + x + '\n' for x in h]
        return ''.join(h) + '\n'

    def support_code(self):
        code = self.build_information().support_code()
        return ''.join(code) + '\n'

    def function_code(self):
        all_function_code = ""
        for func in self.functions:
            all_function_code += func.function_code()
        return ''.join(all_function_code) + '\n'

    def python_function_definition_code(self):
        all_definition_code = ""
        for func in self.functions:
            all_definition_code += func.python_function_definition_code()
        all_definition_code =  indent(''.join(all_definition_code),4)
        code = 'static PyMethodDef compiled_methods[] = \n' \
               '{\n' \
               '%s' \
               '    {NULL,      NULL}        /* Sentinel */\n' \
               '};\n'
        return code % (all_definition_code)

    def module_init_code(self):
        init_code_list =  self.build_information().module_init_code()
        init_code = indent(''.join(init_code_list),4)
        code = 'PyMODINIT_FUNC init%s(void)\n' \
               '{\n' \
               '%s' \
               '    (void) Py_InitModule("%s", compiled_methods);\n' \
               '}\n' % (self.name,init_code,self.name)
        return code

    def generate_file(self,file_name="",location='.'):
        code = self.module_code()
        if not file_name:
            file_name = self.name + '.cpp'
        name = generate_file_name(file_name,location)
        #return name
        return generate_module(code,name)

    def set_compiler(self,compiler):
        # This is not used anymore -- I think we should ditch it.
        #for i in self.arg_specs()
        #    i.set_compiler(compiler)
        for i in self.build_information():
            i.set_compiler(compiler)
        for i in self.functions:
            i.set_compiler(compiler)
        self.compiler = compiler

    def build_kw_and_file(self,location,kw):
        arg_specs = self.arg_specs()
        info = self.build_information()
        _source_files = info.sources()
        # remove duplicates
        source_files = {}
        for i in _source_files:
            source_files[i] = None
        source_files = list(source_files.keys())

        # add internally specified macros, includes, etc. to the key words
        # values of the same names so that distutils will use them.
        kw['define_macros'] = kw.get('define_macros',[]) + \
                              info.define_macros()
        kw['include_dirs'] = kw.get('include_dirs',[]) + info.include_dirs()
        kw['libraries'] = kw.get('libraries',[]) + info.libraries()
        kw['library_dirs'] = kw.get('library_dirs',[]) + info.library_dirs()
        kw['extra_compile_args'] = kw.get('extra_compile_args',[]) + \
                                   info.extra_compile_args()
        kw['extra_link_args'] = kw.get('extra_link_args',[]) + \
                                   info.extra_link_args()
        kw['sources'] = kw.get('sources',[]) + source_files
        file = self.generate_file(location=location)
        return kw,file

    def setup_extension(self,location='.',**kw):
        kw,file = self.build_kw_and_file(location,kw)
        return build_tools.create_extension(file, **kw)

    def compile(self,location='.',compiler=None, verbose = 0, **kw):

        if compiler is not None:
            self.compiler = compiler

        # !! removed -- we don't have any compiler dependent code
        # currently in spec or info classes
        # hmm.  Is there a cleaner way to do this?  Seems like
        # choosing the compiler spagettis around a little.
        #compiler = build_tools.choose_compiler(self.compiler)
        #self.set_compiler(compiler)

        kw,file = self.build_kw_and_file(location,kw)

        # This is needed so that files build correctly even when different
        # versions of Python are running around.
        # Imported at beginning of file now to help with test paths.
        # import catalog
        #temp = catalog.default_temp_dir()
        # for speed, build in the machines temp directory
        temp = catalog.intermediate_dir()

        success = build_tools.build_extension(file, temp_dir = temp,
                                              compiler_name = compiler,
                                              verbose = verbose, **kw)
        if not success:
            raise SystemError('Compilation failed')

def generate_file_name(module_name,module_location):
    module_file = os.path.join(module_location,module_name)
    return os.path.abspath(module_file)

def generate_module(module_string, module_file):
    """ generate the source code file.  Only overwrite
        the existing file if the actual source has changed.
    """
    file_changed = 1
    if os.path.exists(module_file):
        f = open(module_file,'r')
        old_string = f.read()
        f.close()
        if old_string == module_string:
            file_changed = 0
    if file_changed:
        f = open(module_file,'w')
        f.write(module_string)
        f.close()
    return module_file

def assign_variable_types(variables,local_dict = {}, global_dict = {},
                          auto_downcast = 1,
                          type_converters = converters.default):
    incoming_vars = {}
    incoming_vars.update(global_dict)
    incoming_vars.update(local_dict)
    variable_specs = []
    errors={}
    for var in variables:
        try:
            example_type = incoming_vars[var]

            # look through possible type specs to find which one
            # should be used to for example_type
            spec = None
            for factory in type_converters:
                if factory.type_match(example_type):
                    spec = factory.type_spec(var,example_type)
                    break
            if not spec:
                # should really define our own type.
                raise IndexError
            else:
                variable_specs.append(spec)
        except KeyError:
            errors[var] = ("The type and dimensionality specifications" +
                           "for variable '" + var + "' are missing.")
        except IndexError:
            errors[var] = ("Unable to convert variable '"+ var +
                           "' to a C++ type.")
    if errors:
        raise TypeError(format_error_msg(errors))

    if auto_downcast:
        variable_specs = downcast(variable_specs)
    return variable_specs

def downcast(var_specs):
    """ Cast python scalars down to most common type of
         arrays used.

         Right now, focus on complex and float types. Ignore int types.
         Require all arrays to have same type before forcing downcasts.

         Note: var_specs are currently altered in place (horrors...!)
    """
    numeric_types = []

    #grab all the numeric types associated with a variables.
    for var in var_specs:
        if hasattr(var,'numeric_type'):
            numeric_types.append(var.numeric_type)

    # if arrays are present, but none of them are double precision,
    # make all numeric types float or complex(float)
    if (    ('f' in numeric_types or 'F' in numeric_types) and
        not ('d' in numeric_types or 'D' in numeric_types) ):
        for var in var_specs:
            if hasattr(var,'numeric_type'):
                if issubclass(var.numeric_type, complex):
                    var.numeric_type = 'F'
                elif issubclass(var.numeric_type, float):
                    var.numeric_type = 'f'
    return var_specs

def indent(st,spaces):
    indention = ' '*spaces
    indented = indention + st.replace('\n','\n'+indention)
    # trim off any trailing spaces
    indented = re.sub(r' +$',r'',indented)
    return indented

def format_error_msg(errors):
    #minimum effort right now...
    import pprint,io
    msg = io.StringIO()
    pprint.pprint(errors,msg)
    return msg.getvalue()
