import enum

from amaranth.build import Platform
from amaranth import *

class ClockState(enum.Enum):
    LOW     = 0
    FALLING = 1
    HIGH    = 2
    RISING  = 3

class ExiClock(Elaboratable):

    def __init__(self):
        # Ports
        self.exiClk = Signal()
        self.exiClkState = Signal(2)

        # State
        self.prevExiClkValid = Signal()
        self.prevExiClk = Signal()
        self.prevExiClkState = Signal(2)

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

        with m.If(self.prevExiClkValid):
            with m.If(self.prevExiClkState == ClockState.FALLING):
                m.d.comb += self.exiClkState.eq(ClockState.LOW)
            with m.Elif(self.prevExiClkState == ClockState.RISING):
                m.d.comb += self.exiClkState.eq(ClockState.HIGH)
            with m.Else():
                with m.If(self.prevExiClk ^ self.exiClk):
                    m.d.comb += self.exiClkState.eq(Cat(1, self.exiClk))
                with m.Else():
                    m.d.comb += self.exiClkState.eq(Cat(0, self.exiClk))

            m.d.sync += self.prevExiClkState.eq(self.exiClkState)
            
        m.d.sync += self.prevExiClk.eq(self.exiClk)
        m.d.sync += self.prevExiClkValid.eq(1)
        
        return m