use crate::{
    devices::buffer::BufferDevice,
    error::Error,
    gb::{GameBoy, GameBoyMode},
    ppu::FRAME_BUFFER_SIZE,
};

#[derive(Default)]
pub struct TestOptions {
    pub mode: Option<GameBoyMode>,
    pub ppu_enabled: Option<bool>,
    pub apu_enabled: Option<bool>,
    pub dma_enabled: Option<bool>,
    pub timer_enabled: Option<bool>,
}

pub fn build_test(options: TestOptions) -> GameBoy {
    let device = Box::<BufferDevice>::default();
    let mut game_boy = GameBoy::new(options.mode);
    game_boy.set_ppu_enabled(options.ppu_enabled.unwrap_or(true));
    game_boy.set_apu_enabled(options.apu_enabled.unwrap_or(true));
    game_boy.set_dma_enabled(options.dma_enabled.unwrap_or(true));
    game_boy.set_timer_enabled(options.timer_enabled.unwrap_or(true));
    game_boy.attach_serial(device);
    game_boy.load(true);
    game_boy
}

pub fn run_test(
    rom_path: &str,
    max_cycles: Option<u64>,
    options: TestOptions,
) -> Result<GameBoy, Error> {
    let mut cycles = 0u64;
    let max_cycles = max_cycles.unwrap_or(u64::MAX);

    let mut game_boy = build_test(options);
    game_boy.load_rom_file(rom_path, None)?;

    loop {
        cycles += game_boy.clock() as u64;
        if cycles >= max_cycles {
            break;
        }
    }

    Ok(game_boy)
}

pub fn run_step_test(rom_path: &str, addr: u16, options: TestOptions) -> Result<GameBoy, Error> {
    let mut game_boy = build_test(options);
    game_boy.load_rom_file(rom_path, None)?;
    game_boy.step_to(addr);
    Ok(game_boy)
}

pub fn run_serial_test(
    rom_path: &str,
    max_cycles: Option<u64>,
    options: TestOptions,
) -> Result<String, Error> {
    let mut game_boy = run_test(rom_path, max_cycles, options)?;
    Ok(game_boy.serial().device().state())
}

pub fn run_image_test(
    rom_path: &str,
    max_cycles: Option<u64>,
    options: TestOptions,
) -> Result<[u8; FRAME_BUFFER_SIZE], Error> {
    let mut game_boy = run_test(rom_path, max_cycles, options)?;
    Ok(*game_boy.frame_buffer())
}

#[cfg(test)]
mod tests {
    use crate::consts::{DIV_ADDR, TAC_ADDR, TIMA_ADDR, TMA_ADDR};

    use super::{run_serial_test, run_step_test, TestOptions};

    #[test]
    fn test_boot_state() {
        let mut result = run_step_test(
            "res/roms/test/blargg/cpu/cpu_instrs.gb",
            0x0100,
            TestOptions::default(),
        )
        .unwrap();

        assert_eq!(result.cpu_i().pc(), 0x0100);
        assert_eq!(result.cpu_i().sp(), 0xfffe);
        assert_eq!(result.cpu_i().af(), 0x01b0);
        assert_eq!(result.cpu_i().bc(), 0x0013);
        assert_eq!(result.cpu_i().de(), 0x00d8);
        assert_eq!(result.cpu_i().hl(), 0x014d);
        assert_eq!(result.cpu_i().ime(), false);

        assert_eq!(result.mmu().read(DIV_ADDR), 0xab);
        assert_eq!(result.mmu().read(TIMA_ADDR), 0x00);
        assert_eq!(result.mmu().read(TMA_ADDR), 0x00);
        assert_eq!(result.mmu().read(TAC_ADDR), 0xf8);
    }

    #[test]
    fn test_blargg_cpu_instrs() {
        let result = run_serial_test(
            "res/roms/test/blargg/cpu/cpu_instrs.gb",
            Some(300000000),
            TestOptions::default(),
        )
        .unwrap();
        assert_eq!(result, "cpu_instrs\n\n01:ok  02:ok  03:ok  04:ok  05:ok  06:ok  07:ok  08:ok  09:ok  10:ok  11:ok  \n\nPassed all tests\n");
    }

    #[test]
    fn test_blargg_instr_timing() {
        let result = run_serial_test(
            "res/roms/test/blargg/instr_timing/instr_timing.gb",
            Some(50000000),
            TestOptions::default(),
        )
        .unwrap();
        assert_eq!(result, "instr_timing\n\n\nPassed\n");
    }
}