// Copyright (c) 2025 taitep
// SPDX-License-Identifier: BSD-2-Clause
//
// This file is part of TRVE (https://gitea.taitep.se/taitep/trve)
// See LICENSE file in the project root for full license text.

use int_enum::IntEnum;

#[repr(u8)]
#[allow(dead_code)]
#[derive(Debug, Clone, Copy, PartialEq, Eq, IntEnum)]
pub enum ExceptionType {
    InstructionAddressMisaligned = 0,
    InstructionAccessFault = 1,
    IllegalInstruction = 2,
    Breakpoint = 3,
    LoadAddressMisaligned = 4,
    LoadAccessFault = 5,
    StoreAmoAddressMisaligned = 6,
    StoreAmoAccessFault = 7,
    EnvironmentCallFromUMode = 8,
    EnvironmentCallFromSMode = 9,
    EnvironmentCallFromMMode = 11,
    InstructionPageFault = 12,
    LoadPageFault = 13,
    StoreAmoPageFault = 15,
    DoubleTrap = 16,
    SoftwareCheck = 18,
    HardwareError = 19,
}

impl ExceptionType {
    pub fn with_no_value(self) -> Exception {
        Exception {
            type_: self,
            value: 0,
        }
    }
}

#[derive(Debug, Clone, Copy)]
pub struct Exception {
    pub type_: ExceptionType,
    pub value: u64,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum MemoryExceptionType {
    AddressMisaligned,
    AccessFault,
    PageFault,
}

impl MemoryExceptionType {
    pub(crate) fn with_addr(self, addr: u64) -> MemoryException {
        MemoryException { type_: self, addr }
    }
}

#[derive(Debug, Clone, Copy)]
pub struct MemoryException {
    pub type_: MemoryExceptionType,
    pub addr: u64,
}

impl MemoryException {
    pub(crate) fn into_exception_store(self) -> Exception {
        Exception {
            type_: match self.type_ {
                MemoryExceptionType::AddressMisaligned => ExceptionType::StoreAmoAddressMisaligned,
                MemoryExceptionType::AccessFault => ExceptionType::StoreAmoAccessFault,
                MemoryExceptionType::PageFault => ExceptionType::StoreAmoPageFault,
            },
            value: self.addr,
        }
    }

    pub(crate) fn into_exception_instr(self) -> Exception {
        Exception {
            type_: match self.type_ {
                MemoryExceptionType::AddressMisaligned => ExceptionType::InstructionAccessFault,
                MemoryExceptionType::AccessFault => ExceptionType::InstructionAccessFault,
                MemoryExceptionType::PageFault => ExceptionType::InstructionPageFault,
            },
            value: self.addr,
        }
    }

    pub(crate) fn into_exception_load(self) -> Exception {
        Exception {
            type_: match self.type_ {
                MemoryExceptionType::AddressMisaligned => ExceptionType::LoadAddressMisaligned,
                MemoryExceptionType::AccessFault => ExceptionType::LoadAccessFault,
                MemoryExceptionType::PageFault => ExceptionType::LoadPageFault,
            },
            value: self.addr,
        }
    }
}

impl Into<MemoryExceptionType> for MemoryException {
    fn into(self) -> MemoryExceptionType {
        self.type_
    }
}

impl Into<ExceptionType> for Exception {
    fn into(self) -> ExceptionType {
        self.type_
    }
}