import warnings

from migen.fhdl.std import *
from migen.fhdl.structure import _Fragment
from migen.fhdl import verilog
from migen.sim.ipc import *
from migen.sim import icarus

class TopLevel:
	def __init__(self, vcd_name=None, vcd_level=1,
	  top_name="top", dut_type="dut", dut_name="dut",
	  cd_name="sys", clk_period=10):
		self.vcd_name = vcd_name
		self.vcd_level = vcd_level
		self.top_name = top_name
		self.dut_type = dut_type
		self.dut_name = dut_name

		self._cd_name = cd_name
		self._clk_period = clk_period

		cd = ClockDomain(self._cd_name)
		self.clock_domains = [cd]
		self.ios = {cd.clk, cd.rst}

	def get(self, sockaddr):
		template1 = """`timescale 1ns / 1ps

module {top_name}();

reg {clk_name};
reg {rst_name};

initial begin
	{rst_name} <= 1'b1;
	@(posedge {clk_name});
	{rst_name} <= 1'b0;
end

always begin
	{clk_name} <= 1'b0;
	#{hclk_period};
	{clk_name} <= 1'b1;
	#{hclk_period};
end

{dut_type} {dut_name}(
	.{rst_name}({rst_name}),
	.{clk_name}({clk_name})
);

initial $migensim_connect("{sockaddr}");
always @(posedge {clk_name}) $migensim_tick;
"""
		template2 = """
initial begin
	$dumpfile("{vcd_name}");
	$dumpvars({vcd_level}, {dut_name});
end
"""
		r = template1.format(top_name=self.top_name,
			dut_type=self.dut_type,
			dut_name=self.dut_name,
			clk_name=self._cd_name + "_clk",
			rst_name=self._cd_name + "_rst",
			hclk_period=str(self._clk_period/2),
			sockaddr=sockaddr)
		if self.vcd_name is not None:
			r += template2.format(vcd_name=self.vcd_name,
				vcd_level=str(self.vcd_level),
				dut_name=self.dut_name)
		r += "\nendmodule"
		return r

class Simulator:
	def __init__(self, fragment, top_level=None, sim_runner=None, sockaddr="simsocket", **vopts):
		if not isinstance(fragment, _Fragment):
			fragment = fragment.get_fragment()
		if top_level is None:
			top_level = TopLevel()
		if sim_runner is None:
			sim_runner = icarus.Runner()
		self.top_level = top_level
		self.ipc = Initiator(sockaddr)
		self.sim_runner = sim_runner

		c_top = self.top_level.get(sockaddr)

		fragment = fragment + _Fragment(clock_domains=top_level.clock_domains)
		verilog_convert = verilog.convert(fragment,
			ios=self.top_level.ios,
			name=self.top_level.dut_type,
			return_ns=True,
			**vopts)
		c_dut, self.namespace = str(verilog_convert), verilog_convert.ns

		self.cycle_counter = -1

		self.sim_runner = sim_runner
		self.sim_runner.start(c_top, c_dut)
		self.ipc.accept()
		reply = self.ipc.recv()
		assert(isinstance(reply, MessageTick))

		self.sim_functions = fragment.sim
		self.active_sim_functions = set(f for f in fragment.sim if not hasattr(f, "passive") or not f.passive)
		self.unreferenced = {}

	def run(self, ncycles=None):
		counter = 0

		if self.active_sim_functions:
			if ncycles is None:
				def continue_simulation():
					return bool(self.active_sim_functions)
			else:
				def continue_simulation():
					return self.active_sim_functions and counter < ncycles
		else:
			if ncycles is None:
				raise ValueError("No active simulation function present - must specify ncycles to end simulation")
			def continue_simulation():
				return counter < ncycles

		while continue_simulation():
			self.cycle_counter += 1
			counter += 1
			self.ipc.send(MessageGo())
			reply = self.ipc.recv()
			assert(isinstance(reply, MessageTick))

			del_list = []
			for s in self.sim_functions:
				try:
					s(self)
				except StopSimulation:
					del_list.append(s)
			for s in del_list:
				self.sim_functions.remove(s)
				try:
					self.active_sim_functions.remove(s)
				except KeyError:
					pass

	def get_unreferenced(self, item, index):
		try:
			return self.unreferenced[(item, index)]
		except KeyError:
			if isinstance(item, Memory):
				try:
					init = item.init[index]
				except (TypeError, IndexError):
					init = 0
			else:
				init = item.reset
			self.unreferenced[(item, index)] = init
			return init

	def rd(self, item, index=0):
		try:
			name = self.top_level.top_name + "." \
			  + self.top_level.dut_name + "." \
			  + self.namespace.get_name(item)
			self.ipc.send(MessageRead(name, Int32(index)))
			reply = self.ipc.recv()
			assert(isinstance(reply, MessageReadReply))
			value = reply.value
		except KeyError:
			value = self.get_unreferenced(item, index)
		if isinstance(item, Memory):
			signed = False
			nbits = item.width
		else:
			signed = item.signed
			nbits = flen(item)
		value = value & (2**nbits - 1)
		if signed and (value & 2**(nbits - 1)):
			value -= 2**nbits
		return value

	def wr(self, item, value, index=0):
		if isinstance(item, Memory):
			nbits = item.width
		else:
			nbits = flen(item)
		if value < 0:
			value += 2**nbits
		assert(value >= 0 and value < 2**nbits)
		try:
			name = self.top_level.top_name + "." \
			  + self.top_level.dut_name + "." \
			  + self.namespace.get_name(item)
			self.ipc.send(MessageWrite(name, Int32(index), value))
		except KeyError:
			self.unreferenced[(item, index)] = value

	def __del__(self):
		if hasattr(self, "ipc"):
			warnings.warn("call Simulator.close() to clean up "
					"or use it as a contextmanager", DeprecationWarning)
			self.close()

	def close(self):
		self.ipc.close()
		self.sim_runner.close()
		del self.ipc
		del self.sim_runner

	def __enter__(self):
		return self

	def __exit__(self, type, value, traceback):
		self.close()

def run_simulation(fragment, ncycles=None, vcd_name=None, **kwargs):
	with Simulator(fragment, TopLevel(vcd_name), icarus.Runner(**kwargs)) as s:
		s.run(ncycles)