use crate::{heap_drop, heap_move, heap_move_nonnull, ByteSlice};
use servicepoint::{Brightness, BrightnessGrid, ByteGrid, DataRef, Grid};
use std::mem::transmute;
use std::ptr::NonNull;

/// Creates a new [BrightnessGrid] with the specified dimensions.
///
/// returns: [BrightnessGrid] initialized to 0.
///
/// # Examples
/// ```C
/// UdpConnection connection = sp_connection_open("127.0.0.1:2342");
/// if (connection == NULL)
///     return 1;
///
/// BrightnessGrid grid = sp_brightness_grid_new(2, 2);
/// sp_brightness_grid_set(grid, 0, 0, 0);
/// sp_brightness_grid_set(grid, 1, 1, 10);
///
/// TypedCommand command = sp_command_char_brightness(grid);
/// sp_connection_free(connection);
/// ```
#[no_mangle]
pub unsafe extern "C" fn sp_brightness_grid_new(
    width: usize,
    height: usize,
) -> NonNull<BrightnessGrid> {
    heap_move_nonnull(BrightnessGrid::new(width, height))
}

/// Loads a [BrightnessGrid] with the specified dimensions from the provided data.
///
/// returns: new [BrightnessGrid] instance, or NULL in case of an error.
#[no_mangle]
pub unsafe extern "C" fn sp_brightness_grid_load(
    width: usize,
    height: usize,
    data: ByteSlice,
) -> *mut BrightnessGrid {
    let data = unsafe { data.as_slice() };
    let grid = match ByteGrid::load(width, height, data) {
        None => return std::ptr::null_mut(),
        Some(grid) => grid,
    };
    if let Ok(grid) = BrightnessGrid::try_from(grid) {
        heap_move(grid)
    } else {
        std::ptr::null_mut()
    }
}

/// Clones a [BrightnessGrid].
#[no_mangle]
pub unsafe extern "C" fn sp_brightness_grid_clone(
    brightness_grid: NonNull<BrightnessGrid>,
) -> NonNull<BrightnessGrid> {
    heap_move_nonnull(unsafe { brightness_grid.as_ref().clone() })
}

/// Deallocates a [BrightnessGrid].
#[no_mangle]
pub unsafe extern "C" fn sp_brightness_grid_free(
    brightness_grid: NonNull<BrightnessGrid>,
) {
    unsafe { heap_drop(brightness_grid) }
}

/// Gets the current value at the specified position.
///
/// # Arguments
///
/// - `brightness_grid`: instance to read from
/// - `x` and `y`: position of the cell to read
///
/// returns: value at position
///
/// # Panics
/// - When accessing `x` or `y` out of bounds.
#[no_mangle]
pub unsafe extern "C" fn sp_brightness_grid_get(
    brightness_grid: NonNull<BrightnessGrid>,
    x: usize,
    y: usize,
) -> Brightness {
    unsafe { brightness_grid.as_ref().get(x, y) }
}

/// Sets the value of the specified position in the [BrightnessGrid].
///
/// # Arguments
///
/// - `brightness_grid`: instance to write to
/// - `x` and `y`: position of the cell
/// - `value`: the value to write to the cell
///
/// returns: old value of the cell
///
/// # Panics
///
/// - When accessing `x` or `y` out of bounds.
#[no_mangle]
pub unsafe extern "C" fn sp_brightness_grid_set(
    brightness_grid: NonNull<BrightnessGrid>,
    x: usize,
    y: usize,
    value: Brightness,
) {
    unsafe { (*brightness_grid.as_ptr()).set(x, y, value) };
}

/// Sets the value of all cells in the [BrightnessGrid].
///
/// # Arguments
///
/// - `brightness_grid`: instance to write to
/// - `value`: the value to set all cells to
#[no_mangle]
pub unsafe extern "C" fn sp_brightness_grid_fill(
    brightness_grid: NonNull<BrightnessGrid>,
    value: Brightness,
) {
    unsafe { (*brightness_grid.as_ptr()).fill(value) };
}

/// Gets the width of the [BrightnessGrid] instance.
///
/// # Arguments
///
/// - `brightness_grid`: instance to read from
///
/// returns: width
#[no_mangle]
pub unsafe extern "C" fn sp_brightness_grid_width(
    brightness_grid: NonNull<BrightnessGrid>,
) -> usize {
    unsafe { brightness_grid.as_ref().width() }
}

/// Gets the height of the [BrightnessGrid] instance.
///
/// # Arguments
///
/// - `brightness_grid`: instance to read from
///
/// returns: height
#[no_mangle]
pub unsafe extern "C" fn sp_brightness_grid_height(
    brightness_grid: NonNull<BrightnessGrid>,
) -> usize {
    unsafe { brightness_grid.as_ref().height() }
}

/// Gets an unsafe reference to the data of the [BrightnessGrid] instance.
///
/// The returned memory is valid for the lifetime of the brightness grid.
///
/// # Arguments
///
/// - `brightness_grid`: instance to read from
///
/// returns: slice of bytes underlying the `brightness_grid`.
#[no_mangle]
pub unsafe extern "C" fn sp_brightness_grid_unsafe_data_ref(
    brightness_grid: NonNull<BrightnessGrid>,
) -> ByteSlice {
    //noinspection RsAssertEqual
    const _: () = assert!(size_of::<Brightness>() == 1);

    let data = unsafe { (*brightness_grid.as_ptr()).data_ref_mut() };
    unsafe { ByteSlice::from_slice(transmute(data)) }
}