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pub mod traits;

use cpu::Cpu;
use gpu::GPU;
use mmu::Memory;
use mmu::interrupt::Interrupt;
use self::traits::Io;
use joypad::Joypad;

pub struct Emulator {
    cpu: Cpu,
    gpu: GPU,
    memory: Memory,
    joypad: Joypad,
}

impl Emulator {
    pub fn new() -> Emulator {
        Emulator {
            cpu: Cpu::new(),
            gpu: GPU::new(),
            memory: Memory::new(),
            joypad: Joypad::new(),
        }
    }

    pub fn load_rom(&mut self, rom: Vec<u8>) {
        self.memory.load_rom(rom);
    }

    pub fn cycle<T: Io>(&mut self, io: &mut T) {
        let cycles = self.cpu.step(&mut self.memory);
        self.gpu.step(cycles, &mut self.memory, io);
        self.handle_input(io);
        self.handle_interrupts();
    }

    fn handle_input<T: Io>(&mut self, controller: &mut T) {
        controller.update_joypad(&mut self.joypad);
        self.joypad.save_to_memory(&mut self.memory);
    }

    fn handle_interrupts(&mut self) {
        if self.cpu.interrupt_enabled {
            if let Some(interrupt) = self.memory.get_interrupt() {
                self.process_interrupt(interrupt);
            }
        }
    }

    fn process_interrupt(&mut self, interrupt: Interrupt) {

        match interrupt {
            Interrupt::Vblank => self.cpu.rst_40(&mut self.memory),
            Interrupt::Lcd => self.cpu.rst_48(&mut self.memory),
            Interrupt::Timer => self.cpu.rst_50(&mut self.memory),
            Interrupt::Serial => self.cpu.rst_58(&mut self.memory),
            Interrupt::Joypad => self.cpu.rst_60(&mut self.memory),
        }

        self.memory.remove_interrupt(interrupt);
    }
}