import modelverse_kernel.primitives as primitive_functions
import modelverse_jit.tree_ir as tree_ir

KWARGS_PARAMETER_NAME = "remainder"
"""The name of the kwargs parameter in jitted functions."""

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

class ModelverseJit(object):
    """A high-level interface to the modelverse JIT compiler."""

    def __init__(self, max_instructions=None):
        self.todo_entry_points = set()
        self.no_jit_entry_points = set()
        self.jitted_entry_points = {}
        self.jit_globals = {
            'PrimitiveFinished' : primitive_functions.PrimitiveFinished
        }
        self.jit_count = 0
        self.max_instructions = 30 if max_instructions is None else max_instructions

    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.no_jit_entry_points and body_id not in self.jitted_entry_points:
            self.todo_entry_points.add(body_id)

    def is_entry_point(self, body_id):
        """Tells if the node with the given identifier is a function entry point."""
        return body_id in self.todo_entry_points or \
               body_id in self.no_jit_entry_points or \
               body_id in self.jitted_entry_points

    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."""
        return body_id in self.todo_entry_points or \
               body_id in self.jitted_entry_points

    def mark_no_jit(self, body_id):
        """Informs the JIT that the node with the given identifier is a function entry
           point that must never be jitted."""
        self.no_jit_entry_points.add(body_id)
        if body_id in self.todo_entry_points:
            self.todo_entry_points.remove(body_id)

    def register_compiled(self, body_id, compiled):
        """Registers a compiled entry point with the JIT."""
        self.jitted_entry_points[body_id] = compiled
        if body_id in self.todo_entry_points:
            self.todo_entry_points.remove(body_id)

    def try_jit(self, body_id, parameter_list):
        """Tries to jit the function defined by the given entry point id and parameter list."""
        if body_id in self.jitted_entry_points:
            # We have already compiled this function.
            raise primitive_functions.PrimitiveFinished(self.jitted_entry_points[body_id])
        elif body_id in self.no_jit_entry_points:
            # We're not allowed to jit this function or have tried and failed before.
            raise JitCompilationFailedException(
                'Cannot jit function at %d because it is marked non-jittable.' % body_id)

        try:
            gen = AnalysisState(self.max_instructions).analyze(body_id)
            inp = None
            while True:
                inp = yield gen.send(inp)
        except primitive_functions.PrimitiveFinished as ex:
            constructed_body = ex.result
        except JitCompilationFailedException as ex:
            self.mark_no_jit(body_id)
            raise JitCompilationFailedException(
                '%s (function at %d)' % (ex.message, body_id))

        # Wrap the IR in a function definition, give it a unique name.
        constructed_function = tree_ir.DefineFunctionInstruction(
            'jit_func%d' % self.jit_count,
            parameter_list + ['**' + KWARGS_PARAMETER_NAME],
            constructed_body.simplify())
        self.jit_count += 1
        # Convert the function definition to Python code, and compile it.
        exec(str(constructed_function), self.jit_globals)
        # Extract the compiled function from the JIT global state.
        compiled_function = self.jit_globals[constructed_function.name]

        print(constructed_function)

        # Save the compiled function so we can reuse it later.
        self.jitted_entry_points[body_id] = compiled_function
        raise primitive_functions.PrimitiveFinished(compiled_function)

class AnalysisState(object):
    """The state of a bytecode analysis call graph."""

    def __init__(self, max_instructions=None):
        self.analyzed_instructions = set()
        self.max_instructions = max_instructions

    def get_local_name(self, local_id):
        """Gets the name for a local with the given id."""
        return 'local%d' % local_id

    def retrieve_user_root(self):
        """Creates an instruction that stores the user_root variable
           in a local."""
        return tree_ir.StoreLocalInstruction(
            'user_root',
            tree_ir.LoadIndexInstruction(
                tree_ir.LoadLocalInstruction(KWARGS_PARAMETER_NAME),
                tree_ir.LiteralInstruction('user_root')))

    def analyze(self, instruction_id):
        """Tries to build an intermediate representation from the instruction with the
        given id."""
        # Check the analyzed_instructions set for instruction_id to avoid
        # infinite loops.
        if instruction_id in self.analyzed_instructions:
            raise JitCompilationFailedException('Cannot jit non-tree instruction graph.')
        elif (self.max_instructions is not None and
              len(self.analyzed_instructions) > self.max_instructions):
            raise JitCompilationFailedException('Maximal number of instructions exceeded.')

        self.analyzed_instructions.add(instruction_id)
        instruction_val, = yield [("RV", [instruction_id])]
        instruction_val = instruction_val["value"]
        if instruction_val in self.instruction_analyzers:
            gen = self.instruction_analyzers[instruction_val](self, instruction_id)
            try:
                inp = None
                while True:
                    inp = yield gen.send(inp)
            except StopIteration:
                raise Exception(
                    "Instruction analyzer (for '%s') finished without returning a value!" %
                    (instruction_val))
            except primitive_functions.PrimitiveFinished as outer_e:
                # Check if the instruction has a 'next' instruction.
                next_instr, = yield [("RD", [instruction_id, "next"])]
                if next_instr is None:
                    raise outer_e
                else:
                    gen = self.analyze(next_instr)
                    try:
                        inp = None
                        while True:
                            inp = yield gen.send(inp)
                    except primitive_functions.PrimitiveFinished as inner_e:
                        raise primitive_functions.PrimitiveFinished(
                            tree_ir.CompoundInstruction(
                                outer_e.result,
                                inner_e.result))
        else:
            raise JitCompilationFailedException(
                "Unknown instruction type: '%s'" % (instruction_val))

    def analyze_all(self, instruction_ids):
        """Tries to compile a list of IR trees from the given list of instruction ids."""
        results = []
        for inst in instruction_ids:
            gen = self.analyze(inst)
            try:
                inp = None
                while True:
                    inp = yield gen.send(inp)
            except primitive_functions.PrimitiveFinished as ex:
                results.append(ex.result)

        raise primitive_functions.PrimitiveFinished(results)

    def analyze_return(self, instruction_id):
        """Tries to analyze the given 'return' instruction."""
        retval_id, = yield [("RD", [instruction_id, 'value'])]
        if retval_id is None:
            raise primitive_functions.PrimitiveFinished(
                tree_ir.ReturnInstruction(
                    tree_ir.EmptyInstruction()))
        else:
            gen = self.analyze(retval_id)
            try:
                inp = None
                while True:
                    inp = yield gen.send(inp)
            except primitive_functions.PrimitiveFinished as ex:
                raise primitive_functions.PrimitiveFinished(
                    tree_ir.ReturnInstruction(ex.result))

    def analyze_if(self, instruction_id):
        """Tries to analyze the given 'if' instruction."""
        cond, true, false = yield [
            ("RD", [instruction_id, "cond"]),
            ("RD", [instruction_id, "then"]),
            ("RD", [instruction_id, "else"])]

        gen = self.analyze_all(
            [cond, true]
            if false is None
            else [cond, true, false])
        try:
            inp = None
            while True:
                inp = yield gen.send(inp)
        except primitive_functions.PrimitiveFinished as ex:
            if false is None:
                cond_r, true_r = ex.result
                false_r = tree_ir.EmptyInstruction()
            else:
                cond_r, true_r, false_r = ex.result
            raise primitive_functions.PrimitiveFinished(
                tree_ir.SelectInstruction(
                    tree_ir.ReadValueInstruction(cond_r),
                    true_r,
                    false_r))

    def analyze_while(self, instruction_id):
        """Tries to analyze the given 'while' instruction."""
        cond, body = yield [
            ("RD", [instruction_id, "cond"]),
            ("RD", [instruction_id, "body"])]

        gen = self.analyze_all([cond, body])
        try:
            inp = None
            while True:
                inp = yield gen.send(inp)
        except primitive_functions.PrimitiveFinished as ex:
            cond_r, body_r = ex.result
            raise primitive_functions.PrimitiveFinished(
                tree_ir.LoopInstruction(
                    tree_ir.CompoundInstruction(
                        tree_ir.SelectInstruction(
                            tree_ir.ReadValueInstruction(cond_r),
                            tree_ir.EmptyInstruction(),
                            tree_ir.BreakInstruction()),
                        body_r)))

    def analyze_constant(self, instruction_id):
        """Tries to analyze the given 'constant' (literal) instruction."""
        node_id, = yield [("RD", [instruction_id, "node"])]
        raise primitive_functions.PrimitiveFinished(
            tree_ir.LiteralInstruction(node_id))

    def analyze_output(self, instruction_id):
        """Tries to analyze the given 'output' instruction."""

        # The plan is to basically generate this tree:
        #
        # value = <some tree>
        # last_output, last_output_link, new_last_output = \
        #                 yield [("RD", [user_root, "last_output"]),
        #                        ("RDE", [user_root, "last_output"]),
        #                        ("CN", []),
        #                       ]
        # _, _, _, _ = \
        #                 yield [("CD", [last_output, "value", value]),
        #                        ("CD", [last_output, "next", new_last_output]),
        #                        ("CD", [user_root, "last_output", new_last_output]),
        #                        ("DE", [last_output_link])
        #                       ]
        # yield None

        value_id, = yield [("RD", [instruction_id, "value"])]
        gen = self.analyze(value_id)
        try:
            inp = None
            while True:
                inp = yield gen.send(inp)
        except primitive_functions.PrimitiveFinished as ex:
            value_local = tree_ir.StoreLocalInstruction('value', ex.result)

        store_user_root = tree_ir.StoreLocalInstruction(
            'user_root',
            tree_ir.LoadIndexInstruction(
                tree_ir.LoadLocalInstruction(KWARGS_PARAMETER_NAME),
                tree_ir.LiteralInstruction('user_root')))

        last_output = tree_ir.StoreLocalInstruction(
            'last_output',
            tree_ir.ReadDictionaryValueInstruction(
                store_user_root.create_load(),
                tree_ir.LiteralInstruction('last_output')))

        last_output_link = tree_ir.StoreLocalInstruction(
            'last_output_link',
            tree_ir.ReadDictionaryEdgeInstruction(
                store_user_root.create_load(),
                tree_ir.LiteralInstruction('last_output')))

        new_last_output = tree_ir.StoreLocalInstruction(
            'new_last_output',
            tree_ir.CreateNodeInstruction())

        result = tree_ir.create_block(
            value_local,
            store_user_root,
            last_output,
            last_output_link,
            new_last_output,
            tree_ir.CreateDictionaryEdgeInstruction(
                last_output.create_load(),
                tree_ir.LiteralInstruction('value'),
                value_local.create_load()),
            tree_ir.CreateDictionaryEdgeInstruction(
                last_output.create_load(),
                tree_ir.LiteralInstruction('next'),
                new_last_output.create_load()),
            tree_ir.CreateDictionaryEdgeInstruction(
                store_user_root.create_load(),
                tree_ir.LiteralInstruction('last_output'),
                new_last_output.create_load()),
            tree_ir.DeleteEdgeInstruction(last_output_link.create_load()),
            tree_ir.NopInstruction())

        raise primitive_functions.PrimitiveFinished(result)

    def analyze_resolve(self, instruction_id):
        """Tries to analyze the given 'resolve' instruction."""
        var_id, = yield [("RD", [instruction_id, "var"])]
        var_name, = yield [("RV", [var_id])]

        # To resolve a variable, we'll do something along the
        # lines of:
        #
        #     if 'local_var' in locals():
        #         tmp = local_var
        #     else:
        #         _globals, = yield [("RD", [user_root, "globals"])]
        #         global_var, = yield [("RD", [_globals, var_name])]
        #
        #         if global_var is None:
        #             raise Exception("Runtime error: global '%s' not found" % (var_name))
        #
        #         tmp = global_var

        user_root = self.retrieve_user_root()
        global_var = tree_ir.StoreLocalInstruction(
            'global_var',
            tree_ir.ReadDictionaryValueInstruction(
                tree_ir.ReadDictionaryValueInstruction(
                    user_root.create_load(),
                    tree_ir.LiteralInstruction('globals')),
                tree_ir.LiteralInstruction(var_name)))

        err_block = tree_ir.SelectInstruction(
            tree_ir.BinaryInstruction(
                global_var.create_load(),
                'is',
                tree_ir.LiteralInstruction(None)),
            tree_ir.RaiseInstruction(
                tree_ir.CallInstruction(
                    tree_ir.LoadLocalInstruction('Exception'),
                    [tree_ir.LiteralInstruction(
                        "Runtime error: global '%s' not found" % var_name)
                    ])),
            tree_ir.EmptyInstruction())

        name = self.get_local_name(var_id)
        raise primitive_functions.PrimitiveFinished(
            tree_ir.SelectInstruction(
                tree_ir.LocalExistsInstruction(name),
                tree_ir.LoadLocalInstruction(name),
                tree_ir.CompoundInstruction(
                    tree_ir.create_block(
                        user_root,
                        global_var,
                        err_block),
                    global_var.create_load())))

    def analyze_declare(self, instruction_id):
        """Tries to analyze the given 'declare' function."""
        var_id, = yield [("RD", [instruction_id, "var"])]

        name = self.get_local_name(var_id)

        # The following logic declares a local:
        #
        #     if 'local_name' not in locals():
        #         local_name, = yield [("CN", [])]

        raise primitive_functions.PrimitiveFinished(
            tree_ir.SelectInstruction(
                tree_ir.LocalExistsInstruction(name),
                tree_ir.EmptyInstruction(),
                tree_ir.StoreLocalInstruction(
                    name,
                    tree_ir.CreateNodeInstruction())))

    def analyze_global(self, instruction_id):
        """Tries to analyze the given 'global' (declaration) instruction."""
        var_id, = yield [("RD", [instruction_id, "var"])]
        var_name, = yield [("RV", [var_id])]

        # To resolve a variable, we'll do something along the
        # lines of:
        #
        #     _globals, = yield [("RD", [user_root, "globals"])]
        #     global_var = yield [("RD", [_globals, var_name])]
        #
        #     if global_var is None:
        #         global_var, = yield [("CN", [])]
        #         yield [("CD", [_globals, var_name, global_var])]
        #
        #     tmp = global_var

        user_root = self.retrieve_user_root()
        _globals = tree_ir.StoreLocalInstruction(
            '_globals',
            tree_ir.ReadDictionaryValueInstruction(
                user_root.create_load(),
                tree_ir.LiteralInstruction('globals')))

        global_var = tree_ir.StoreLocalInstruction(
            'global_var',
            tree_ir.ReadDictionaryValueInstruction(
                _globals.create_load(),
                tree_ir.LiteralInstruction(var_name)))

        raise primitive_functions.PrimitiveFinished(
            tree_ir.CompoundInstruction(
                tree_ir.create_block(
                    user_root,
                    _globals,
                    global_var,
                    tree_ir.SelectInstruction(
                        tree_ir.BinaryInstruction(
                            global_var.create_load(),
                            'is',
                            tree_ir.LiteralInstruction(None)),
                        tree_ir.create_block(
                            global_var.create_store(
                                tree_ir.CreateNodeInstruction()),
                            tree_ir.CreateDictionaryEdgeInstruction(
                                _globals.create_load(),
                                tree_ir.LiteralInstruction(var_name),
                                global_var.create_load())),
                        tree_ir.EmptyInstruction())),
                global_var.create_load()))

    def analyze_assign(self, instruction_id):
        """Tries to analyze the given 'assign' instruction."""
        var_id, value_id = yield [("RD", [instruction_id, "var"]),
                                  ("RD", [instruction_id, "value"])]

        try:
            gen = self.analyze_all([var_id, value_id])
            inp = None
            while True:
                inp = yield gen.send(inp)
        except primitive_functions.PrimitiveFinished as ex:
            var_r, value_r = ex.result

        # Assignments work like this:
        #
        #     value_link = yield [("RDE", [variable, "value"])]
        #     _, _ =       yield [("CD", [variable, "value", value]),
        #                         ("DE", [value_link])]

        variable = tree_ir.StoreLocalInstruction('variable', var_r)
        value = tree_ir.StoreLocalInstruction('value', value_r)
        value_link = tree_ir.StoreLocalInstruction(
            'value_link',
            tree_ir.ReadDictionaryEdgeInstruction(
                variable.create_load(),
                tree_ir.LiteralInstruction('value')))

        raise primitive_functions.PrimitiveFinished(
            tree_ir.create_block(
                variable,
                value,
                value_link,
                tree_ir.CreateDictionaryEdgeInstruction(
                    variable.create_load(),
                    tree_ir.LiteralInstruction('value'),
                    value.create_load()),
                tree_ir.DeleteEdgeInstruction(
                    value_link.create_load())))

    def analyze_access(self, instruction_id):
        """Tries to analyze the given 'access' instruction."""
        var_id, = yield [("RD", [instruction_id, "var"])]

        try:
            gen = self.analyze(var_id)
            inp = None
            while True:
                inp = yield gen.send(inp)
        except primitive_functions.PrimitiveFinished as ex:
            var_r = ex.result

        # Accessing a variable is pretty easy. It really just boils
        # down to reading the value corresponding to the 'value' key
        # of the variable.
        #
        #     value, =  yield [("RD", [returnvalue, "value"])]

        raise primitive_functions.PrimitiveFinished(
            tree_ir.ReadDictionaryValueInstruction(
                var_r,
                tree_ir.LiteralInstruction('value')))

    instruction_analyzers = {
        'if' : analyze_if,
        'while' : analyze_while,
        'return' : analyze_return,
        'constant' : analyze_constant,
        'resolve' : analyze_resolve,
        'declare' : analyze_declare,
        'global' : analyze_global,
        'assign' : analyze_assign,
        'access' : analyze_access,
        'output' : analyze_output
    }