use crate::{
    consts::{Addr, RegId, RegValue},
    mem::MemConfig,
};

#[derive(PartialEq, Debug, Clone, Copy)]
pub enum ExecutionStatus {
    Running,
    Paused,
    Halted,
}

pub struct Core {
    x_regs: [RegValue; 32],
    pc: Addr,
    mem: MemConfig,
    exec_status: ExecutionStatus,
}

impl Core {
    pub fn new(mem: MemConfig) -> Self {
        Self {
            x_regs: [0; 32],
            pc: 0,
            mem,
            exec_status: ExecutionStatus::Halted,
        }
    }

    pub fn reset(&mut self, pc: Addr) {
        self.pc = pc;
        self.exec_status = ExecutionStatus::Running;
    }

    pub fn resume(&mut self) -> ExecutionStatus {
        if self.exec_status == ExecutionStatus::Halted {
            ExecutionStatus::Halted
        } else {
            self.exec_status = ExecutionStatus::Running;
            ExecutionStatus::Running
        }
    }

    pub fn exec_status(&self) -> ExecutionStatus {
        self.exec_status
    }

    fn reg_read(&self, id: RegId) -> RegValue {
        self.x_regs[id as usize]
    }

    fn reg_write(&mut self, id: RegId, value: RegValue) {
        if id == 0 {
            return;
        }
        self.x_regs[id as usize] = value;
    }
}