from functools import reduce
from operator import or_

from nmigen import *

from rtio.sed import layouts
from rtio.sed.output_network import OutputNetwork

__all__ = ["OutputDriver"]

class OutputDriver(Elaboratable):
    def __init__(self, channels, glbl_fine_ts_width, lane_count, seqn_width):
        self.channels = channels
        self.glbl_fine_ts_width = glbl_fine_ts_width
        self.lane_count = lane_count
        self.seqn_width = seqn_width

        self.collision = Signal()
        self.collision_channel = Signal(range(len(channels)), reset_less=True)
        self.busy = Signal()
        self.busy_channel = Signal(range(len(channels)), reset_less=True)

        # output network
        layout_on_payload = layouts.output_network_payload(channels, glbl_fine_ts_width)
        self.output_network = OutputNetwork(lane_count, seqn_width, layout_on_payload)
        self.input = self.output_network.input

        # detect collisions (adds one pipeline stage)
        layout_lane_data = [
            ("valid", 1),
            ("collision", 1),
            ("payload", layout_on_payload)
        ]
        self.lane_datas = [Record(layout_lane_data) for _ in range(lane_count)]
        for lane_data in self.lane_datas:
            lane_data.valid.reset_less = True
            lane_data.collision.reset_less = True
            for field, _ in layout_on_payload:
                getattr(lane_data.payload, field).reset_less = True
        self.en_replaces = [channel.interface.o.enable_replace for channel in channels]

    def elaborate(self, platform):
        m = Module()

        channels = self.channels
        output_network = self.output_network
        lane_datas = self.lane_datas
        en_replaces = self.en_replaces

        m.submodules += self.output_network
        for lane_data, on_output in zip(lane_datas, output_network.output):
            lane_data.valid.reset_less = False
            lane_data.collision.reset_less = False
            replace_occured_r = Signal()
            nondata_replace_occured_r = Signal()
            m.d.sync += lane_data.valid.eq(on_output.valid)
            m.d.sync += lane_data.payload.eq(on_output.payload)
            m.d.sync += replace_occured_r.eq(on_output.replace_occured)
            m.d.sync += nondata_replace_occured_r.eq(on_output.nondata_replace_occured)

            en_replaces_rom = Memory(width=1, depth=len(en_replaces), init=en_replaces)
            en_replaces_rom_port = en_replaces_rom.read_port()
            m.submodules += en_replaces_rom_port
            m.d.comb += en_replaces_rom_port.addr.eq(on_output.payload.channel)
            m.d.comb += lane_data.collision.eq(replace_occured_r & (~en_replaces_rom_port.data | nondata_replace_occured_r))

        m.d.sync += self.collision.eq(0)
        m.d.sync += self.collision_channel.eq(0)
        for lane_data in lane_datas:
            with m.If(lane_data.valid & lane_data.collision):
                m.d.sync += self.collision.eq(1)
                m.d.sync += self.collision_channel.eq(lane_data.payload.channel)

        # demultiplex channels (adds one pipeline stage)
        for n, channel in enumerate(channels):
            oif = channel.interface.o

            onehot_stb = []
            onehot_fine_ts = []
            onehot_address = []
            onehot_data = []
            for lane_data in lane_datas:
                selected = Signal()
                m.d.comb += selected.eq(lane_data.valid & ~lane_data.collision & (lane_data.payload.channel == n))
                onehot_stb.append(selected)
                if hasattr(lane_data.payload, "fine_ts") and hasattr(oif, "fine_ts"):
                    ts_shift = len(lane_data.payload.fine_ts) - len(oif.fine_ts)
                    onehot_fine_ts.append(Mux(selected, lane_data.payload.fine_ts[ts_shift:], 0))
                if hasattr(lane_data.payload, "address"):
                    onehot_address.append(Mux(selected, lane_data.payload.address, 0))
                if hasattr(lane_data.payload, "data"):
                    onehot_data.append(Mux(selected, lane_data.payload.data, 0))

            m.d.sync += oif.stb.eq(reduce(or_, onehot_stb))
            if hasattr(oif, "fine_ts"):
                m.d.sync += oif.fine_ts.eq(reduce(or_, onehot_fine_ts))
            if hasattr(oif, "address"):
                m.d.sync += oif.address.eq(reduce(or_, onehot_address))
            if hasattr(oif, "data"):
                m.d.sync += oif.data.eq(reduce(or_, onehot_data))

        # detect busy errors, at lane level to reduce mixing
        m.d.sync += self.busy.eq(0)
        m.d.sync += self.busy_channel.eq(0)
        for lane_data in lane_datas:
            stb_r = Signal()
            channel_r = Signal(range(len(channels)), reset_less=True)
            m.d.sync += stb_r.eq(lane_data.valid & ~lane_data.collision)
            m.d.sync += channel_r.eq(lane_data.payload.channel)

            with m.If(stb_r & Array(channel.interface.o.busy for channel in channels)[channel_r]):
                m.d.sync += self.busy.eq(1)
                m.d.sync += self.busy_channel.eq(channel_r)

        return m