use servicepoint::{Bitmap, DataRef, Grid};
use std::ptr::NonNull;

use crate::byte_slice::ByteSlice;

/// Creates a new [Bitmap] with the specified dimensions.
///
/// # Arguments
///
/// - `width`: size in pixels in x-direction
/// - `height`: size in pixels in y-direction
///
/// returns: [Bitmap] initialized to all pixels off, or NULL in case of an error.
///
/// # Errors
///
/// In the following cases, this function will return NULL:
///
/// - when the width is not dividable by 8
///
/// # Examples
///
/// ```C
/// Cp437Grid grid = sp_bitmap_new(8, 3);
/// sp_bitmap_fill(grid, true);
/// sp_bitmap_set(grid, 0, 0, false);
/// sp_bitmap_free(grid);
/// ```
#[no_mangle]
pub unsafe extern "C" fn sp_bitmap_new(
    width: usize,
    height: usize,
) -> *mut Bitmap {
    if let Some(bitmap) = Bitmap::new(width, height) {
        Box::leak(Box::new(bitmap))
    } else {
        std::ptr::null_mut()
    }
}

/// Creates a new [Bitmap] with a size matching the screen.
///
/// returns: [Bitmap] initialized to all pixels off.
#[no_mangle]
pub unsafe extern "C" fn sp_bitmap_new_screen_sized() -> NonNull<Bitmap> {
    let result = Box::new(Bitmap::max_sized());
    NonNull::from(Box::leak(result))
}

/// Loads a [Bitmap] with the specified dimensions from the provided data.
///
/// # Arguments
///
/// - `width`: size in pixels in x-direction
/// - `height`: size in pixels in y-direction
///
/// returns: [Bitmap] that contains a copy of the provided data, or NULL in case of an error.
#[no_mangle]
pub unsafe extern "C" fn sp_bitmap_load(
    width: usize,
    height: usize,
    data: ByteSlice,
) -> *mut Bitmap {
    let data = unsafe { data.as_slice() };
    if let Ok(bitmap) = Bitmap::load(width, height, data) {
        Box::leak(Box::new(bitmap))
    } else {
        std::ptr::null_mut()
    }
}

/// Clones a [Bitmap].
#[no_mangle]
pub unsafe extern "C" fn sp_bitmap_clone(
    bitmap: NonNull<Bitmap>,
) -> NonNull<Bitmap> {
    let result = Box::new(unsafe { bitmap.as_ref().clone() });
    NonNull::from(Box::leak(result))
}

/// Deallocates a [Bitmap].
#[no_mangle]
pub unsafe extern "C" fn sp_bitmap_free(bitmap: NonNull<Bitmap>) {
    _ = unsafe { Box::from_raw(bitmap.as_ptr()) };
}

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

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

/// Sets the state of all pixels in the [Bitmap].
///
/// # Arguments
///
/// - `bitmap`: instance to write to
/// - `value`: the value to set all pixels to
#[no_mangle]
pub unsafe extern "C" fn sp_bitmap_fill(bitmap: NonNull<Bitmap>, value: bool) {
    unsafe { (*bitmap.as_ptr()).fill(value) };
}

/// Gets the width in pixels of the [Bitmap] instance.
///
/// # Arguments
///
/// - `bitmap`: instance to read from
///
/// # Panics
///
/// - when `bitmap` is NULL
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - `bitmap` points to a valid [Bitmap]
#[no_mangle]
pub unsafe extern "C" fn sp_bitmap_width(bitmap: NonNull<Bitmap>) -> usize {
    unsafe { bitmap.as_ref().width() }
}

/// Gets the height in pixels of the [Bitmap] instance.
///
/// # Arguments
///
/// - `bitmap`: instance to read from
#[no_mangle]
pub unsafe extern "C" fn sp_bitmap_height(bitmap: NonNull<Bitmap>) -> usize {
    unsafe { bitmap.as_ref().height() }
}

/// Gets an unsafe reference to the data of the [Bitmap] instance.
///
/// The returned memory is valid for the lifetime of the bitmap.
#[no_mangle]
pub unsafe extern "C" fn sp_bitmap_unsafe_data_ref(
    mut bitmap: NonNull<Bitmap>,
) -> ByteSlice {
    unsafe { ByteSlice::from_slice(bitmap.as_mut().data_ref_mut()) }
}