"""
BSD 2-Clause License

Copyright (c) 2019-2021, Linux-on-LiteX-VexRiscv Developers
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this
   list of conditions and the following disclaimer.

2. Redistributions in binary form must reproduce the above copyright notice,
   this list of conditions and the following disclaimer in the documentation
   and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
"""

from migen import *
from migen.genlib import fsm
from migen.genlib import fifo
from migen.genlib import cdc

from migen.fhdl.decorators import ModuleTransformer
from litex.soc.interconnect.csr import CSRStorage, CSRStatus, CSRField, CSR, AutoCSR



# Hack the AutoCSR objects to enable access only via Module attributes.
class CSRTransform(ModuleTransformer):
    def __init__(self, parent):
        self.parent = parent

    def transform_instance(self, i):
        # Capture all the available CSRs, then burn the bridge.
        v = i.get_csrs()
        i.get_csrs = None
        
        for c in v:
            # Skip over modules already exposed, should handle potential renaming here.
            #if hasattr(i, c.name):
            #    pass

            # Attach csr as module attribute
            setattr(i, c.name,c)

            if isinstance(c, CSR):
                ...
            else:
                # Clear the finalise function so these aren't altered further.
                # Maybe not required?
                def _null(*kwargs):
                    ...   
                c.finalize = _null

                # Attach these to our modules submodules,
                # needed to ensure the objects are elaborated?
                self.parent.submodules += c

            # create extra bindings to support dev writing
            if isinstance(c, CSRStorage):
                    # .re is used to determine when .storage has been updated.
                    # so we need to create delayed re signal, we'll rename this to re0
                    setattr(c, "re0", c.re)
                    setattr(c.re0, "name", c.name + '_re0')

                    # Our personal .re signal will then update .re0 alongside .storage
                    setattr(c, "re", Signal(name=c.name + '_re'))
                    c.sync += c.re0.eq(c.re)

                    if hasattr(c, "fields"):
                        setattr(c, "dat_w", Record([]))
                        for a in c.fields.fields:
                            s = Signal(a.size,name=f'{c.name}_{a.name}0')

                            c.sync += If(c.re, 
                                c.storage[a.offset:a.offset + a.size].eq(s)
                            )
                            setattr(c.dat_w, a.name, s)

                    else:
                        # if the CSRStorage doesn't have any fields, just provide .dat_w
                        setattr(c, "dat_w", Signal(c.size))
                        c.sync += If(c.re, c.storage.eq(c.dat_w))