use ferris_boi::{
    cpu::{instructions::RunnableInstruction, Processor},
    register,
};

use test_case::test_matrix;

use crate::testutil;

struct AdditionOperationFlags {
    half_carry: u8,
    carry: u8,
}

#[test]
fn test_add_hl_to_itself() {
    let mut processor = Processor::default();
    processor.registers.set_16bit_register(
        register::SixteenBit::Combined(register::Combined::HL),
        0x2244,
    );
    let data = [0x29, 0x02];

    let (ins, extra_data) =
        RunnableInstruction::from_data(&data).expect("could not parse instruction");
    assert_eq!(extra_data, &[0x02]);

    processor.run_instruction(&ins);

    assert_eq!(
        0x4488,
        processor
            .registers
            .get_combined_register(register::Combined::HL)
    );
}

#[test_matrix(
    [
        (0x09, register::SixteenBit::Combined(register::Combined::BC)),
        (0x19, register::SixteenBit::Combined(register::Combined::DE)),
        (0x39, register::SixteenBit::Single(register::SingleSixteenBit::StackPointer)),
    ],
    [
        (0xAAAA, 0x1122, 0xBBCC),
        (0xFFFF, 0x0002, 0x0001),
    ]
)]
fn test_add_hl_to_registers_value(
    (opcode, operand_register): (u8, register::SixteenBit),
    (hl_value, operand_value, expected): (u16, u16, u16),
) {
    let mut processor = Processor::default();
    processor.registers.set_16bit_register(
        register::SixteenBit::Combined(register::Combined::HL),
        hl_value,
    );
    processor
        .registers
        .set_16bit_register(operand_register, operand_value);
    let data = [opcode, 0x02];

    let (ins, extra_data) =
        RunnableInstruction::from_data(&data).expect("could not parse instruction");
    assert_eq!(extra_data, &[0x02]);

    processor.run_instruction(&ins);

    assert_eq!(
        expected,
        processor
            .registers
            .get_combined_register(register::Combined::HL)
    );
}

#[test_matrix(
    [
        (0x09, register::SixteenBit::Combined(register::Combined::BC)),
        (0x19, register::SixteenBit::Combined(register::Combined::DE)),
        (0x39, register::SixteenBit::Single(register::SingleSixteenBit::StackPointer)),
    ],
    [
        (0xAAAA, 0x1122, AdditionOperationFlags{ half_carry: 0, carry: 0}),
        (0xAAAA, 0x0FFF, AdditionOperationFlags{ half_carry: 1, carry: 0}),
        (0xFFFF, 0x0001, AdditionOperationFlags{ half_carry: 1, carry: 1}),
        (0xFFFF, 0x0002, AdditionOperationFlags{ half_carry: 1, carry: 1}),
        (0x8000, 0xC000, AdditionOperationFlags{ half_carry: 0, carry: 1}),
    ]
)]
fn test_add_hl_to_registers_flags(
    (opcode, operand_register): (u8, register::SixteenBit),
    (hl_value, operand_value, expected_flags): (u16, u16, AdditionOperationFlags),
) {
    let mut processor = Processor::default();
    processor.registers.set_16bit_register(
        register::SixteenBit::Combined(register::Combined::HL),
        hl_value,
    );
    processor
        .registers
        .set_16bit_register(operand_register, operand_value);
    let data = [opcode, 0x02];

    let (ins, extra_data) =
        RunnableInstruction::from_data(&data).expect("could not parse instruction");
    assert_eq!(extra_data, &[0x02]);

    // Set all the register to the opposite we expect to ensure they all get set
    testutil::set_opposite_of_expected_flags(
        &mut processor,
        (0, 0, expected_flags.half_carry, expected_flags.carry),
    );

    processor.run_instruction(&ins);

    testutil::assert_flags_eq!(
        processor,
        (register::Flag::Zero, 1),
        (register::Flag::Subtract, 0),
        (register::Flag::HalfCarry, expected_flags.half_carry),
        (register::Flag::Carry, expected_flags.carry),
    );
}

#[test_matrix(
    [
        (0x03, register::SixteenBit::Combined(register::Combined::BC)),
        (0x13, register::SixteenBit::Combined(register::Combined::DE)),
        (0x23, register::SixteenBit::Combined(register::Combined::HL)),
        (0x33, register::SixteenBit::Single(register::SingleSixteenBit::StackPointer)),
    ],
    [
        (0xAAAA, 0xAAAB),
        (0xFFFF, 0x0000),
        (0x0000, 0x0001),
    ]
)]
fn test_increment(
    (opcode, operand_register): (u8, register::SixteenBit),
    (start_value, expected): (u16, u16),
) {
    let mut processor = Processor::default();
    processor
        .registers
        .set_16bit_register(operand_register, start_value);
    processor
        .registers
        .set_raw_flag_bits(0xA0)
        .expect("Failed to set flag bits");
    let data = [opcode, 0x02];

    let (ins, extra_data) =
        RunnableInstruction::from_data(&data).expect("could not parse instruction");
    assert_eq!(extra_data, &[0x02]);

    processor.run_instruction(&ins);

    assert_eq!(
        expected,
        processor.registers.get_16bit_register(operand_register)
    );
    // Flags are untouched
    assert_eq!(0xA0, processor.registers.get_raw_flag_bits());
}

#[test_matrix(
    [
        (0x0B, register::SixteenBit::Combined(register::Combined::BC)),
        (0x1B, register::SixteenBit::Combined(register::Combined::DE)),
        (0x2B, register::SixteenBit::Combined(register::Combined::HL)),
        (0x3B, register::SixteenBit::Single(register::SingleSixteenBit::StackPointer)),
    ],
    [
        (0xAAAB, 0xAAAA),
        (0x0000, 0xFFFF),
        (0x0001, 0x0000),
    ]
)]
fn test_decrement(
    (opcode, operand_register): (u8, register::SixteenBit),
    (start_value, expected): (u16, u16),
) {
    let mut processor = Processor::default();
    processor
        .registers
        .set_16bit_register(operand_register, start_value);
    processor
        .registers
        .set_raw_flag_bits(0xA0)
        .expect("Failed to set flag bits");
    let data = [opcode, 0x02];

    let (ins, extra_data) =
        RunnableInstruction::from_data(&data).expect("could not parse instruction");
    assert_eq!(extra_data, &[0x02]);

    processor.run_instruction(&ins);

    assert_eq!(
        expected,
        processor.registers.get_16bit_register(operand_register)
    );
    // Flags are untouched
    assert_eq!(0xA0, processor.registers.get_raw_flag_bits());
}