#include <cstdio>
#include <cstdlib>

#include "../include/chip8.h"
#include "../include/instruction.h"
#include "../include/instruction_handler.h"

Chip8::Chip8() : instructionHandler(), display() {
    this->pc = 0x200;
}

Chip8::~Chip8() {
    delete instructionHandler;
}

/**
 * Reads all bytes from 0x200 onward and put them in the memory.
 * If the file does not exist, the program is exited.
 *
 * @param file The Chip8 rom file
 * @todo Check if the Chip8 rom file is a valid rom file
 */
void Chip8::loadRom(const std::string& file) {
    FILE* game = fopen(("roms/" + file).c_str(), "rb");
    if (game == nullptr) {

        exit(EXIT_FAILURE);
    }

    fread(this->memory + 0x200, sizeof(char), 0xFFF - 0x200, game);
    fclose(game);
}

Display Chip8::getDisplay() const {
    return this->display;
}

/**
 * This emulates one cycle by getting the opcode and handling the instruction corresponding that opcode
 */
void Chip8::emulateCycle() {
    unsigned short opcode = (this->memory[this->pc] << 8 | this->memory[this->pc + 1]);
    this->pc += 2;
    this->instructionHandler->handleInstruction(opcode & 0xF000, *this, Instruction(opcode));
}

/**
 * Gets the value from the top of the stack, pop the top of the stack and returns the value
 * @return A 16-bit value from the stack
 */
unsigned short Chip8::popFromStack() {
    unsigned short value = this->stack.top();
    this->stack.pop();
    return value;
}

void Chip8::pushToStack(unsigned short value) {
    this->stack.push(value);
}

void Chip8::setProgramCounter(unsigned short value) {
    this->pc = value;
}

unsigned short Chip8::getProgramCounter() const {
    return this->pc;
}