use crate::{heap_drop, heap_move_nonnull, ByteSlice};
use servicepoint::BitVecU8Msb0;
use std::ptr::NonNull;

/// A vector of bits
///
/// # Examples
/// ```C
/// SPBitVec vec = sp_bitvec_new(8);
/// sp_bitvec_set(vec, 5, true);
/// sp_bitvec_free(vec);
/// ```
pub struct SPBitVec(pub(crate) BitVecU8Msb0);

impl Clone for SPBitVec {
    fn clone(&self) -> Self {
        SPBitVec(self.0.clone())
    }
}

/// Creates a new [SPBitVec] instance.
///
/// # Arguments
///
/// - `size`: size in bits.
///
/// returns: [SPBitVec] with all bits set to false.
///
/// # Panics
///
/// - when `size` is not divisible by 8.
#[no_mangle]
pub unsafe extern "C" fn sp_bitvec_new(size: usize) -> NonNull<SPBitVec> {
    heap_move_nonnull(SPBitVec(BitVecU8Msb0::repeat(false, size)))
}

/// Interpret the data as a series of bits and load then into a new [SPBitVec] instance.
///
/// returns: [SPBitVec] instance containing data.
#[no_mangle]
pub unsafe extern "C" fn sp_bitvec_load(data: ByteSlice) -> NonNull<SPBitVec> {
    let data = unsafe { data.as_slice() };
    heap_move_nonnull(SPBitVec(BitVecU8Msb0::from_slice(data)))
}

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

/// Deallocates a [SPBitVec].
#[no_mangle]
pub unsafe extern "C" fn sp_bitvec_free(bit_vec: NonNull<SPBitVec>) {
    unsafe { heap_drop(bit_vec) }
}

/// Gets the value of a bit from the [SPBitVec].
///
/// # Arguments
///
/// - `bit_vec`: instance to read from
/// - `index`: the bit index to read
///
/// returns: value of the bit
///
/// # Panics
///
/// - when accessing `index` out of bounds
#[no_mangle]
pub unsafe extern "C" fn sp_bitvec_get(
    bit_vec: NonNull<SPBitVec>,
    index: usize,
) -> bool {
    unsafe { *bit_vec.as_ref().0.get(index).unwrap() }
}

/// Sets the value of a bit in the [SPBitVec].
///
/// # Arguments
///
/// - `bit_vec`: instance to write to
/// - `index`: the bit index to edit
/// - `value`: the value to set the bit to
///
/// # Panics
///
/// - when accessing `index` out of bounds
#[no_mangle]
pub unsafe extern "C" fn sp_bitvec_set(
    bit_vec: NonNull<SPBitVec>,
    index: usize,
    value: bool,
) {
    unsafe { (*bit_vec.as_ptr()).0.set(index, value) }
}

/// Sets the value of all bits in the [SPBitVec].
///
/// # Arguments
///
/// - `bit_vec`: instance to write to
/// - `value`: the value to set all bits to
#[no_mangle]
pub unsafe extern "C" fn sp_bitvec_fill(
    bit_vec: NonNull<SPBitVec>,
    value: bool,
) {
    unsafe { (*bit_vec.as_ptr()).0.fill(value) }
}

/// Gets the length of the [SPBitVec] in bits.
///
/// # Arguments
///
/// - `bit_vec`: instance to write to
#[no_mangle]
pub unsafe extern "C" fn sp_bitvec_len(bit_vec: NonNull<SPBitVec>) -> usize {
    unsafe { bit_vec.as_ref().0.len() }
}

/// Returns true if length is 0.
///
/// # Arguments
///
/// - `bit_vec`: instance to write to
#[no_mangle]
pub unsafe extern "C" fn sp_bitvec_is_empty(
    bit_vec: NonNull<SPBitVec>,
) -> bool {
    unsafe { bit_vec.as_ref().0.is_empty() }
}

/// Gets an unsafe reference to the data of the [SPBitVec] instance.
///
/// The returned memory is valid for the lifetime of the bitvec.
///
/// # Arguments
///
/// - `bit_vec`: instance to write to
#[no_mangle]
pub unsafe extern "C" fn sp_bitvec_unsafe_data_ref(
    bit_vec: NonNull<SPBitVec>,
) -> ByteSlice {
    unsafe { ByteSlice::from_slice((*bit_vec.as_ptr()).0.as_raw_mut_slice()) }
}