import math
import keyword
from collections import defaultdict
import modelverse_kernel.primitives as primitive_functions

class ModelverseJit(object):
    """A high-level interface to the modelverse JIT compiler."""
    def __init__(self):
        self.todo_entry_points = set()
        self.jitted_parameters = {}
        self.jit_globals = {}
        # jitted_entry_points maps body ids to values in jit_globals.
        self.jitted_entry_points = {}
        # global_functions maps global value names to body ids.
        self.global_functions = {}
        # global_functions_inv maps body ids to global value names.
        self.global_functions_inv = {}
        # jitted_function_aliases maps body ids to known aliases.
        self.jitted_function_aliases = defaultdict(set)
        self.jit_count = 0
        self.compilation_dependencies = {}
        self.cache = {}

    def mark_entry_point(self, body_id):
        """Marks the node with the given identifier as a function entry point."""
        if body_id not in self.jitted_entry_points:
            self.todo_entry_points.add(body_id)

    def is_jittable_entry_point(self, body_id):
        """Tells if the node with the given identifier is a function entry point that
           has not been marked as non-jittable. This only returns `True` if the JIT
           is enabled and the function entry point has been marked jittable, or if
           the function has already been compiled."""
        return ((body_id in self.todo_entry_points) or (body_id in self.jitted_entry_points))

    def generate_name(self, infix, suggested_name=None):
        """Generates a new name or picks the suggested name if it is still
           available."""
        if suggested_name is not None \
            and suggested_name not in self.jit_globals \
            and not keyword.iskeyword(suggested_name):
            self.jit_count += 1
            return suggested_name
        else:
            function_name = 'jit_%s%d' % (infix, self.jit_count)
            self.jit_count += 1
            return function_name

    def generate_function_name(self, body_id, suggested_name=None):
        """Generates a new function name or picks the suggested name if it is still
           available."""
        if suggested_name is None:
            suggested_name = self.get_global_name(body_id)

        return self.generate_name('func', suggested_name)

    def register_global(self, body_id, global_name):
        """Associates the given body id with the given global name."""
        self.global_functions[global_name] = body_id
        self.global_functions_inv[body_id] = global_name

    def get_global_name(self, body_id):
        """Gets the name of the global function with the given body id.
           Returns None if no known global exists with the given id."""
        if body_id in self.global_functions_inv:
            return self.global_functions_inv[body_id]
        else:
            return None

    def get_global_body_id(self, global_name):
        """Gets the body id of the global function with the given name.
           Returns None if no known global exists with the given name."""
        if global_name in self.global_functions:
            return self.global_functions[global_name]
        else:
            return None

    def register_compiled(self, body_id, compiled_function, function_name=None):
        """Registers a compiled entry point with the JIT."""
        # Get the function's name.
        actual_function_name = self.generate_function_name(body_id, function_name)
        # Map the body id to the given parameter list.
        self.jitted_entry_points[body_id] = actual_function_name
        self.jit_globals[actual_function_name] = compiled_function
        if function_name is not None:
            self.register_global(body_id, function_name)

        if body_id in self.todo_entry_points:
            self.todo_entry_points.remove(body_id)

    def __lookup_compiled_body_impl(self, body_id):
        """Looks up a compiled function by body id. Returns a matching function,
           or None if no function was found."""
        if body_id is not None and body_id in self.jitted_entry_points:
            return self.jit_globals[self.jitted_entry_points[body_id]]
        else:
            return None

    def __lookup_external_body_impl(self, global_name, body_id):
        """Looks up an external function by global name. Returns a matching function,
           or None if no function was found."""
        if global_name is not None and self.compiled_function_lookup is not None:
            result = self.compiled_function_lookup(global_name)
            if result is not None and body_id is not None:
                self.register_compiled(body_id, result, global_name)

            return result
        else:
            return None

    def lookup_compiled_body(self, body_id):
        """Looks up a compiled function by body id. Returns a matching function,
           or None if no function was found."""
        result = self.__lookup_compiled_body_impl(body_id)
        if result is not None:
            return result
        else:
            global_name = self.get_global_name(body_id)
            return self.__lookup_external_body_impl(global_name, body_id)

    def lookup_compiled_function(self, global_name):
        """Looks up a compiled function by global name. Returns a matching function,
           or None if no function was found."""
        body_id = self.get_global_body_id(global_name)
        result = self.__lookup_compiled_body_impl(body_id)
        if result is not None:
            return result
        else:
            return self.__lookup_external_body_impl(global_name, body_id)

    def jit_signature(self, body_id):
        """Acquires the signature for the given body id node, which consists of the
           parameter variables, parameter name and a flag that tells if the given function
           is mutable."""
        if body_id not in self.jitted_parameters:
            signature_id, = yield [("RRD", [body_id, "body"])]
            signature_id = signature_id[0]
            param_set_id, is_mutable = yield [
                ("RD", [signature_id, "params"]),
                ("RD", [signature_id, "mutable"])]
            if param_set_id is None:
                self.jitted_parameters[body_id] = ([], [], is_mutable)
            else:
                param_name_ids, = yield [("RDK", [param_set_id])]
                param_names = yield [("RV", [n]) for n in param_name_ids]
                #NOTE Patch up strange links...
                param_names = [i for i in param_names if i is not None]
                param_vars = yield [("RD", [param_set_id, k]) for k in param_names]

                #NOTE that variables might not be in the correct order, as we just read them out!
                lst = sorted([(name, var) for name, var in zip(param_names, param_vars)])
                param_vars = [i[1] for i in lst]
                param_names = [i[0] for i in lst]
                self.jitted_parameters[body_id] = (param_vars, param_names, is_mutable)

        yield [("RETURN", [self.jitted_parameters[body_id]])]

    def check_jittable(self, body_id, suggested_name=None):
        """Checks if the function with the given body id is obviously non-jittable. If it's
           non-jittable, then a `JitCompilationFailedException` exception is thrown."""
        if body_id is None:
            raise ValueError('body_id cannot be None: ' + suggested_name)

    def jit_define_function(self, function_name, function_def):
        """Converts the given tree-IR function definition to Python code, defines it,
           and extracts the resulting function."""
        # The comment below makes pylint shut up about our (hopefully benign) use of exec here.
        # pylint: disable=I0011,W0122
        if self.jit_code_log_function is not None:
            self.jit_code_log_function(function_def)

        # Convert the function definition to Python code, and compile it.
        code_generator = tree_ir.PythonGenerator()
        function_def.generate_python_def(code_generator)
        source_map_name = self.get_source_map_name(function_name)
        if source_map_name is not None:
            self.jit_globals[source_map_name] = code_generator.source_map_builder.source_map
        exec(str(code_generator), self.jit_globals)

        # Extract the compiled function from the JIT global state.
        return self.jit_globals[function_name]

    def jit_delete_function(self, function_name):
        """Deletes the function with the given function name."""
        del self.jit_globals[function_name]
import modelverse_kernel.primitives as primitive_functions

class JitCompilationFailedException(Exception):
    """A type of exception that is raised when the jit fails to compile a function."""
    pass