# --------------------------------------------------------------------
# SPDX-License-Identifier: AGPL-3.0-or-later
# © Copyright 2008-2024 José Manuel Rodríguez de la Rosa and contributors.
# See the file CONTRIBUTORS.md for copyright details.
# See https://www.gnu.org/licenses/agpl-3.0.html for details.
# --------------------------------------------------------------------

import re
from collections import UserDict
from collections.abc import Mapping
from types import MappingProxyType
from typing import Final

from . import asm
from .helpers import (
    HI16,
    HL_SEP,
    LO16,
    LO16_val,
    get_H_from_unknown_value,
    get_L_from_unknown_value,
    get_orig_label_from_unknown16,
    idx_args,
    is_8bit_oper_register,
    is_16bit_composed_register,
    is_label,
    is_number,
    is_register,
    is_unknown,
    is_unknown8,
    is_unknown16,
    new_tmp_val,
    new_tmp_val16,
    new_tmp_val16_from_label,
    to_int,
    valnum,
)

RE_OFFSET = re.compile(r"(^[*._a-zA-Z0-9]+(?:[+-]\d+)*)([+-]\d+)$")


class Flags:
    def __init__(self):
        self.C = None
        self.Z = None
        self.P = None
        self.S = None


class Memory(UserDict[str, str]):
    """Implements a memory representation, dealing with unknown values"""

    def __init__(self):
        super().__init__()

    def _get_hl_addr(self, addr: str) -> tuple[str, str]:
        if is_number(addr):
            return addr, str(to_int(addr) + 1)

        ptr = RE_OFFSET.match(addr)
        if ptr is None:
            return addr, f"{addr}+1"

        base, off, *_ = ptr.groups()
        off = int(off)
        if off == 0:
            return self._get_hl_addr(base)

        if off == -1:
            return addr, base

        return addr, "%s%+i" % (base, off + 1)

    def read_16_bit_value(self, addr: str) -> str:
        addr_lo, addr_hi = self._get_hl_addr(addr)
        hi = self[addr_hi]
        lo = self[addr_lo]
        if is_number(hi) and is_number(lo):
            return str(valnum(lo) + 256 * valnum(hi))

        result = f"{hi}|{lo}"
        if (label_ := get_orig_label_from_unknown16("")) is not None:
            return label_

        return result

    def write_16_bit_value(self, addr: str, value: str) -> None:
        if is_number(value):
            value_ = valnum(value)
            v_hi = str((value_ >> 8) & 0xFF)
            v_lo = str(value_ & 0xFF)
        else:
            if is_unknown16(value):
                v_ = value
            else:
                v_ = new_tmp_val16_from_label(value)
            v_hi = get_H_from_unknown_value(v_)
            v_lo = get_L_from_unknown_value(v_)

        addr_lo, addr_hi = self._get_hl_addr(addr)
        self.data[addr_lo] = v_lo
        self.data[addr_hi] = v_hi

    def read_8_bit_value(self, addr: str) -> str:
        addr_lo, _ = self._get_hl_addr(addr)
        lo = self[addr_lo]
        if is_number(lo):
            return str(int(lo) & 0xFF)

        return lo

    def write_8_bit_value(self, addr: str, value: str) -> None:
        if is_number(value):
            value = str(valnum(value) & 0xFF)
        elif is_unknown16(value):
            value = get_L_from_unknown_value(value)
        elif is_label(value):
            value = get_L_from_unknown_value(new_tmp_val16_from_label(value))

        addr_lo, _ = self._get_hl_addr(addr)
        self.data[addr_lo] = value

    def __missing__(self, key: str) -> str:
        self.data[key] = new_tmp_val()
        return self.data[key]


class CPUState:
    """A class storing registers value information (CPU State)."""

    mem: Memory
    stack: list[str]
    regs: dict[str, str]
    _flags: tuple[Flags, Flags]

    # Given an 8 bit reg. Return the 16 bit reg it belongs to.
    _16bit: Final[MappingProxyType[str, str]] = {
        "b": "bc",
        "c": "bc",
        "d": "de",
        "e": "de",
        "h": "hl",
        "l": "hl",
        "b'": "bc'",
        "c'": "bc'",
        "d'": "de'",
        "e'": "de'",
        "h'": "hl'",
        "l'": "hl'",
        "ixh": "ix",
        "ixl": "ix",
        "iyh": "iy",
        "iyl": "iy",
        "a": "af",
        "a'": "af'",
        "f": "af",
        "f'": "af'",
    }

    # Given a 16 bit regs, returns its 8 bits pair
    _8bit: Final[MappingProxyType[str, tuple[str, str]]] = {
        "af": ("a", "f"),
        "bc": ("b", "c"),
        "de": ("d", "e"),
        "hl": ("h", "l"),
        "af'": ("a'", "f'"),
        "bc'": ("b'", "c'"),
        "de'": ("d'", "e'"),
        "hl'": ("h'", "l'"),
        "ix": ("ixh", "ixl"),
        "iy": ("iyh", "iyl"),
    }

    def __init__(self):
        self.reset()

    @property
    def Z(self):
        """The Z flag"""
        return self._flags[0].Z

    @Z.setter
    def Z(self, val):
        """Sets the Z flag, and tries to update the F register accordingly.
        If the F register is unknown, sets it with a new unknown value.
        """
        assert is_unknown(val) or val in (0, 1)
        self._flags[0].Z = val
        if not is_unknown(val) and is_number(self.regs["f"]):
            self.regs["f"] = str((self.getv("f") & 0xBF) | (val << 6))
        else:
            self.regs["f"] = new_tmp_val()

    @property
    def C(self):
        """The C flag"""
        return self._flags[0].C

    @C.setter
    def C(self, val):
        """Sets the C flag, and tries to update the F register accordingly.
        If the F register is unknown, sets it with a new unknown value.
        """
        assert is_unknown(val) or val in (0, 1)
        self._flags[0].C = val

        if not is_unknown(val) and is_number(self.regs["f"]):
            self.regs["f"] = str((self.getv("f") & 0xFE) | val)
        else:
            self.regs["f"] = new_tmp_val()

    @property
    def P(self):
        """The P flag"""
        return self._flags[0].P

    @P.setter
    def P(self, val):
        """Sets the P flag, and tries to update the F register accordingly.
        If the F register is unknown, sets it with a new unknown value.
        """
        assert is_unknown(val) or val in (0, 1)
        self._flags[0].P = val
        if not is_unknown(val) and is_number(self.regs["f"]):
            self.regs["f"] = str((self.getv("f") & 0xFB) | (val << 2))
        else:
            self.regs["f"] = new_tmp_val()

    @property
    def S(self):
        """The S flag"""
        return self._flags[0].S

    @S.setter
    def S(self, val):
        """Sets the S flag, and tries to update the F register accordingly.
        If the F register is unknown, sets it with a new unknown value.
        """
        assert is_unknown(val) or val in (0, 1)
        self._flags[0].S = val
        if not is_unknown(val) and is_number(self.regs["f"]):
            self.regs["f"] = str((self.getv("f") & 0x7F) | (val << 7))
        else:
            self.regs["f"] = new_tmp_val()

    def reset(self, regs=None, mems: Mapping[str, str] | None = None):
        """Initial state"""
        if regs is None:
            regs = {}

        if mems is None:
            mems = {}

        self.regs = {}
        self.stack = []
        self.mem = Memory()  # dict of label -> value in memory
        self._flags = Flags(), Flags()

        # # Memory for IX / IY accesses
        self.ix_ptr = set()

        for i in "abcdefhl":
            self.regs[i] = new_tmp_val()  # Initial unknown state
            self.regs["%s'" % i] = new_tmp_val()

        self.regs["ixh"] = new_tmp_val()
        self.regs["ixl"] = new_tmp_val()
        self.regs["iyh"] = new_tmp_val()
        self.regs["iyl"] = new_tmp_val()
        self.regs["sp"] = new_tmp_val()
        self.regs["r"] = new_tmp_val()
        self.regs["i"] = new_tmp_val()

        for i in "af", "bc", "de", "hl":
            self.regs[i] = f"{self.regs[i[0]]}{HL_SEP}{self.regs[i[1]]}"
            self.regs["%s'" % i] = "{}{}{}".format(self.regs["%s'" % i[0]], HL_SEP, self.regs["%s'" % i[1]])

        self.regs["ix"] = "{}{}{}".format(self.regs["ixh"], HL_SEP, self.regs["ixl"])
        self.regs["iy"] = "{}{}{}".format(self.regs["iyh"], HL_SEP, self.regs["iyl"])

        self.regs.update(**regs)
        self.mem.update(**mems)

        for key_ in mems:
            idx = idx_args(key_)
            if idx:
                self.ix_ptr.add(idx)

        self.reset_flags()

    def reset_flags(self) -> None:
        """Resets flags to an "unknown state" """
        self.C = None
        self.Z = None
        self.P = None
        self.S = None

    def clear_idx_reg_refs(self, r: str) -> None:
        """For the given ix/iy, remove all references of it in memory, which are not in the form
        ix/iy +/- n
        """
        r = r.lower()
        assert r in ("ix", "iy")

        for k in list(self.ix_ptr):
            if k[0] != r:
                continue

            if not is_number(k[2]):
                del self.mem["{}{}{}".format(*k)]
                self.ix_ptr.remove(k)

    def shift_idx_regs_refs(self, r: str, offset: int) -> None:
        """Given an idx register r (ix / iy) and an offset, all the references in memory
        will be shifted the given amount.
        I.e. for 'ix', 1
            (ix + 1) will contain (ix + 2), and so on.
            (ix + 127) will contain an unknown8 value

        The same applies for negative offsets. For iy - 2
            (iy + 2) will contain current (iy + 0)
            (iy - 126) and lower will contain random unknown8
        """
        if offset == 0:
            return

        self.clear_idx_reg_refs(r)
        r = r.lower()
        if offset > 0:
            for i in range(-128, 128):
                idx = "%s%+i" % (r, i)
                old_idx = "%s%+i" % (r, offset + i)
                self.mem.write_8_bit_value(
                    idx, new_tmp_val() if offset + i > 127 else self.mem.read_8_bit_value(old_idx)
                )
        else:
            for i in range(127, -129, -1):
                idx = "%s%+i" % (r, i)
                old_idx = "%s%+i" % (r, offset + i)
                self.mem.write_8_bit_value(
                    idx, new_tmp_val() if offset + i < -128 else self.mem.read_8_bit_value(old_idx)
                )

    def set(self, r: str, val: int | str | None) -> None:
        orig_val = val
        val = self.get(val)
        is_num = is_number(val)

        if val is None:
            val = new_tmp_val16()
        else:
            val = str(val)

        if is_num:
            val = str(valnum(val) & 0xFFFF)

        if self.getv(r) == val:
            return  # The register already contains this

        if r == "(sp)":
            if not self.stack:
                self.stack = [new_tmp_val16()]

            self.stack[-1] = val
            return

        if r in {"(hl)", "(bc)", "(de)"}:  # ld (bc|de|hl), val
            r = self.regs[r[1:-1]]
            self.mem.write_8_bit_value(r, val)
            return

        if r[0] == "(":  # (mem) <- r  => store in memory address
            r = r[1:-1].strip()
            idx = idx_args(r)
            if idx is not None:
                r = "{}{}{}".format(*idx)
                self.ix_ptr.add(idx)
                val = LO16_val(val)
                self.mem.write_8_bit_value(r, val)
                return

            if is_8bit_oper_register(orig_val):
                self.mem.write_8_bit_value(r, val)
                return

            if is_unknown8(val):
                val = f"{new_tmp_val()}{HL_SEP}{val}"

            self.mem.write_16_bit_value(r, val)
            return

        if is_8bit_oper_register(r):
            oldval = self.getv(r)
            if is_num:
                val = str(valnum(val) & 0xFF)
            else:
                val = get_L_from_unknown_value(val)

            if val == oldval:  # Does not change
                return

            self.regs[r] = val
            if r not in self._16bit:
                return

            hl = self._16bit[r]
            h_, l_ = (self.regs[r] for r in self._8bit[hl])
            if is_number(h_) and is_number(l_):
                self.regs[hl] = str((valnum(h_) << 8) | valnum(l_))
                return

            self.regs[hl] = f"{h_}{HL_SEP}{l_}"
            return

        # a 16 bit reg
        assert r in self.regs

        if is_unknown8(val):
            val = f"{new_tmp_val()}{HL_SEP}{val}"
        assert is_num or is_unknown16(val) or is_label(val), (
            f"val '{val}' is neither a number, nor a label nor an unknown16"
        )

        self.regs[r] = val
        if is_16bit_composed_register(r):  # sp register is not included. Special case
            if not is_num:
                if is_label(val):
                    val = new_tmp_val16_from_label(val)
                self.regs[HI16(r)], self.regs[LO16(r)] = val.split(HL_SEP)
            else:
                val = valnum(val)
                self.regs[HI16(r)], self.regs[LO16(r)] = str(val >> 8), str(val & 0xFF)

            if "f" in r:
                self.reset_flags()

    def get(self, r: str | int | None) -> str | None:
        """Returns precomputed value of the given expression"""
        if r is None:
            return None

        r = str(r)

        if r.lower() == "(sp)" and self.stack:
            return self.stack[-1]

        if r.lower() in {"(hl)", "(bc)", "(de)"}:
            i = self.regs[r.lower()[1:-1]]
            return self.mem.read_8_bit_value(i)

        if r[:1] == "(":
            v_ = r[1:-1].strip()
            idx = idx_args(v_)
            if idx is not None:
                v_ = "{}{}{}".format(*idx)
                self.ix_ptr.add(idx)
                return self.mem.read_8_bit_value(v_)

            return self.mem.read_16_bit_value(v_)

        if is_number(r):
            return str(valnum(r))

        if is_unknown(r):
            return r

        r_ = r.lower()
        if not is_register(r_):  # If it's not a register, it *must* be a label
            return r

        return self.regs[r_]

    def getv(self, r: str) -> int | None:
        """Like the above, but returns the <int> value or None."""
        v = self.get(r)
        result: int | None = None
        if not is_unknown(v):
            try:
                result = int(v)
            except ValueError:
                pass
        return result

    def eq(self, r1: str, r2: str) -> bool:
        """True if values of r1 and r2 registers are equal"""
        if not is_register(r1) or not is_register(r2):
            return False

        if self.regs[r1] is None or self.regs[r2] is None:  # HINT: This's been never USED??
            return False

        return self.regs[r1] == self.regs[r2]

    def set_flag(self, val: str | None) -> None:
        if not is_number(val):
            self.regs["f"] = new_tmp_val()
            self.reset_flags()
            return

        self.set("f", val)
        val = valnum(val)
        self.C = val & 1
        self.P = (val >> 2) & 1
        self.Z = (val >> 6) & 1
        self.S = (val >> 7) & 1

    def inc(self, r):
        """Does inc on the register and precomputes flags"""
        if not is_register(r):
            if r[0] == "(":  # a memory position, basically: inc(hl)
                v_ = self.getv(r)
                if v_ is not None:
                    v_ = (v_ + 1) & 0xFF
                    self.Z = int(v_ == 0)  # HINT: This might be improved
                    self.C = int(v_ == 0)
                else:
                    v_ = new_tmp_val()
                    self.set_flag(None)

                r_ = r[1:-1]
                self.mem.write_8_bit_value(self.get(r_), str(v_))
            return

        if self.getv(r) is not None:
            self.set(r, self.getv(r) + 1)
        else:
            self.set(r, None)

        if r in ("ix", "iy"):
            self.shift_idx_regs_refs(r, 1)

        if not is_8bit_oper_register(r):  # INC does not affect flag for 16bit regs
            return

        if is_unknown(self.regs[r]):
            self.set_flag(None)
            return

        v_ = self.getv(r)
        self.Z = int(v_ == 0)
        self.C = int(v_ == 0)

    def dec(self, r):
        """Does dec on the register and precomputes flags"""
        if not is_register(r):
            v_ = self.getv(r)
            if v_ is not None:
                v_ = (v_ - 1) & 0xFF
                self.Z = int(v_ == 0)  # HINT: This might be improved
                self.C = int(v_ == 0xFF)
            else:
                v_ = new_tmp_val()
                self.set_flag(None)

            r_ = r[1:-1]
            self.mem.write_8_bit_value(self.get(r_), str(v_))
            return

        if self.getv(r) is not None:
            self.set(r, self.getv(r) - 1)
        else:
            self.set(r, None)

        if r in ("ix", "iy"):
            self.shift_idx_regs_refs(r, -1)

        if not is_8bit_oper_register(r):  # DEC does not affect flag for 16bit regs
            return

        if is_unknown(self.regs[r]):
            self.set_flag(None)
            return

        v_ = self.getv(r)
        self.Z = int(v_ == 0)
        self.C = int(v_ == 0xFF)

    def rrc(self, r):
        """Does a ROTATION to the RIGHT |>>"""
        if not is_number(self.regs[r]):
            self.set(r, None)
            self.set_flag(None)
            return

        v_ = self.getv(self.regs[r]) & 0xFF
        self.regs[r] = str((v_ >> 1) | ((v_ & 1) << 7))

    def rr(self, r):
        """Like the above, bus uses carry"""
        if self.C is None or not is_number(self.regs[r]):
            self.set(r, None)
            self.set_flag(None)
            return

        self.rrc(r)
        tmp = self.C
        v_ = self.getv(self.regs[r])
        self.C = v_ >> 7
        self.regs[r] = str((v_ & 0x7F) | (tmp << 7))

    def rlc(self, r):
        """Does a ROTATION to the LEFT <<|"""
        if not is_number(self.regs[r]):
            self.set(r, None)
            self.set_flag(None)
            return

        v_ = self.getv(self.regs[r]) & 0xFF
        self.set(r, ((v_ << 1) & 0xFF) | (v_ >> 7))

    def rl(self, r):
        """Like the above, bus uses carry"""
        if self.C is None or not is_number(self.regs[r]):
            self.set(r, None)
            self.set_flag(None)
            return

        self.rlc(r)
        tmp = self.C
        v_ = self.getv(self.regs[r])
        self.C = v_ & 1
        self.regs[r] = str((v_ & 0xFE) | tmp)

    def _is(self, r, val):
        """True if value of r is val."""
        if not is_register(r) or val is None:
            return False

        r = r.lower()
        if is_register(val):
            return self.eq(r, val)

        if is_number(val):
            val = str(valnum(val))
        else:
            val = str(val)

        if val[0] == "(":
            val = self.mem[val[1:-1]]

        return self.regs[r] == val

    def execute(self, asm_code: str) -> None:
        """Tries to update the registers values with the given
        asm line.
        """
        asm_ = asm.Asm(asm_code)
        if asm_.is_label:
            return

        i = asm_.inst
        o = asm_.oper

        for ii in range(len(o)):
            if is_register(o[ii]):
                o[ii] = o[ii].lower()

        if i == "ld":
            self.set(o[0], o[1])
            return

        if i == "push":
            if valnum(self.regs["sp"]) is not None:
                self.set("sp", (self.getv(self.regs["sp"]) - 2) % 0xFFFF)
            else:
                self.set("sp", None)
            self.stack.append(self.regs[o[0]])
            return

        if i == "pop":
            self.set(o[0], self.stack and self.stack.pop() or None)
            if valnum(self.regs["sp"]):
                self.set("sp", (self.getv(self.regs["sp"]) + 2) % 0xFFFF)
            else:
                self.set("sp", None)
            return

        if i == "inc":
            self.inc(o[0])
            return

        if i == "dec":
            self.dec(o[0])
            return

        if i == "rra":
            self.rr("a")
            return
        if i == "rla":
            self.rl("a")
            return
        if i == "rlca":
            self.rlc("a")
            return
        if i == "rrca":
            self.rrc("a")
            return
        if i == "rr":
            self.rr(o[0])
            return
        if i == "rl":
            self.rl(o[0])
            return

        if i == "exx":
            for j in "bc", "de", "hl", "b", "c", "d", "e", "h", "l":
                self.regs[j], self.regs["%s'" % j] = self.regs["%s'" % j], self.regs[j]
            return

        if i == "ex":
            if o == ["de", "hl"]:
                for a, b in [("de", "hl"), ("d", "h"), ("e", "l")]:
                    self.regs[a], self.regs[b] = self.regs[b], self.regs[a]
            else:
                for j in "af", "a", "f":
                    self.regs[j], self.regs["%s'" % j] = self.regs["%s'" % j], self.regs[j]
            return

        if i == "xor":
            self.C = 0

            if o[0] == "a":
                self.set("a", 0)
                self.Z = 1
                return

            if self.getv("a") is None or self.getv(o[0]) is None:
                self.Z = None
                self.set("a", None)
                return

            self.set("a", self.getv("a") ^ self.getv(o[0]))
            self.Z = int(self.get("a") == 0)
            return

        if i in ("or", "and"):
            self.C = 0

            if self.getv("a") is None or self.getv(o[0]) is None:
                self.Z = None
                self.set("a", None)
                return

            if i == "or":
                self.set("a", self.getv("a") | self.getv(o[0]))
            else:
                self.set("a", self.getv("a") & self.getv(o[0]))

            self.Z = int(self.get("a") == 0)
            return

        if i in ("adc", "sbc"):
            if len(o) == 1:
                o = ["a", o[0]]

            if self.C is None:
                self.Z = None
                self.set(o[0], None)
                return

            if i == "sbc" and o[0] == o[1]:
                self.Z = int(not self.C)
                self.set(o[0], -self.C)
                return

            if self.getv(o[0]) is None or self.getv(o[1]) is None:
                self.set_flag(None)
                self.set(o[0], None)
                return

            if i == "adc":
                val = self.getv(o[0]) + self.getv(o[1]) + self.C
                if is_8bit_oper_register(o[0]):
                    self.C = int(val > 0xFF)
                else:
                    self.C = int(val > 0xFFFF)
                self.set(o[0], val)
                return

            val = self.getv(o[0]) - self.getv(o[1]) - self.C
            self.C = int(val < 0)
            self.Z = int(val == 0)
            self.set(o[0], val)
            return

        if i in ("add", "sub"):
            if len(o) == 1:
                o = ["a", o[0]]

            if i == "sub" and o[0] == o[1]:
                self.Z = 1
                self.C = 0
                self.set(o[0], 0)
                return

            if not is_number(self.get(o[0])) or is_number(self.get(o[1])) is not None:
                self.set_flag(None)
                self.set(o[0], None)
                return

            if i == "add":
                val = self.getv(o[0]) + self.getv(o[1])
                if is_8bit_oper_register(o[0]):
                    self.C = int(val > 0xFF)
                    val &= 0xFF
                    self.Z = int(val == 0)
                    self.S = val >> 7
                else:
                    self.C = int(val > 0xFFFF)
                    val &= 0xFFFF

                self.set(o[0], val)
                return

            val = self.getv(o[0]) - self.getv(o[1])
            if is_8bit_oper_register(o[0]):
                self.C = int(val < 0)
                val &= 0xFF
                self.Z = int(val == 0)
                self.S = val >> 7
            else:
                self.C = int(val < 0)
                val &= 0xFFFF

            self.set(o[0], val)
            return

        if i == "neg":
            if self.getv("a") is None:
                self.set("a", None)
                self.set_flag(None)
                return

            val = -self.getv("a")
            self.set("a", val)
            self.Z = int(not val)
            self.C = int(not self.Z)
            val &= 0xFF
            self.S = val >> 7
            return

        if i == "scf":
            self.C = 1
            return

        if i == "ccf":
            if self.C is not None:
                self.C = int(not self.C)
            return

        if i == "cpl":
            if self.getv("a") is None:
                self.set("a", None)
                return

            self.set("a", 0xFF ^ self.getv("a"))
            return

        if i == "cp":
            val = self.getv(o[0])
            if not is_number(self.regs["a"]) or is_unknown(val):
                self.set_flag(None)
                return

            val = int(self.regs["a"]) - val
            self.Z = int(val == 0)
            self.C = int(val < 0)
            self.S = int(val < 0)
            return

        if i in {"jp", "jr", "ret", "rst", "call"}:
            return

        if i == "djnz":
            if self.getv("b") is None:
                self.set("b", None)
                self.Z = None
                return

            val = (self.getv("b") - 1) & 0xFF
            self.set("b", val)
            self.Z = int(val == 0)
            return

        if i == "out":
            return

        if i == "in":
            self.set(o[0], None)
            return

        # Unknown. Resets ALL
        self.reset()

    def __repr__(self):
        return "\n".join(f"{x}: {y}" for x, y in self.regs.items())
