//! C functions for interacting with [SPCommand]s
//!
//! prefix `sp_command_`

use std::ptr::null_mut;

use servicepoint::{Brightness, Origin};

use crate::{
    SPBitVec, SPBrightnessGrid, SPCompressionCode, SPCp437Grid, SPPacket,
    SPBitmap,
};

/// A low-level display command.
///
/// This struct and associated functions implement the UDP protocol for the display.
///
/// To send a [SPCommand], use a [SPConnection].
///
/// # Examples
///
/// ```C
/// sp_connection_send_command(connection, sp_command_clear());
/// sp_connection_send_command(connection, sp_command_brightness(5));
/// ```
pub struct SPCommand(pub(crate) servicepoint::Command);

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

/// Tries to turn a [SPPacket] into a [SPCommand].
///
/// The packet is deallocated in the process.
///
/// Returns: pointer to new [SPCommand] instance or NULL if parsing failed.
///
/// # Panics
///
/// - when `packet` is NULL
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - [SPPacket] points to a valid instance of [SPPacket]
/// - [SPPacket] is not used concurrently or after this call
/// - the result is checked for NULL
/// - the returned [SPCommand] instance is freed in some way, either by using a consuming function or
///   by explicitly calling `sp_command_free`.
#[no_mangle]
pub unsafe extern "C" fn sp_command_try_from_packet(
    packet: *mut SPPacket,
) -> *mut SPCommand {
    let packet = *Box::from_raw(packet);
    match servicepoint::Command::try_from(packet.0) {
        Err(_) => null_mut(),
        Ok(command) => Box::into_raw(Box::new(SPCommand(command))),
    }
}

/// Clones a [SPCommand] instance.
///
/// returns: new [SPCommand] instance. Will never return NULL.
///
/// # Panics
///
/// - when `command` is NULL
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - `command` points to a valid instance of [SPCommand]
/// - `command` is not written to concurrently
/// - the returned [SPCommand] instance is freed in some way, either by using a consuming function or
///   by explicitly calling `sp_command_free`.
#[no_mangle]
pub unsafe extern "C" fn sp_command_clone(
    command: *const SPCommand,
) -> *mut SPCommand {
    assert!(!command.is_null());
    let result = Box::into_raw(Box::new((*command).clone()));
    assert!(!result.is_null());
    result
}

/// Set all pixels to the off state.
///
/// Does not affect brightness.
///
/// Returns: a new [Command::Clear] instance. Will never return NULL.
///
/// # Examples
///
/// ```C
/// sp_connection_send_command(connection, sp_command_clear());
/// ```
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - the returned [SPCommand] instance is freed in some way, either by using a consuming function or
///   by explicitly calling `sp_command_free`.
#[no_mangle]
pub unsafe extern "C" fn sp_command_clear() -> *mut SPCommand {
    let result = Box::into_raw(Box::new(SPCommand(servicepoint::Command::Clear)));
    assert!(!result.is_null());
    result
}

/// Kills the udp daemon on the display, which usually results in a restart.
///
/// Please do not send this in your normal program flow.
///
/// Returns: a new [Command::HardReset] instance. Will never return NULL.
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - the returned [SPCommand] instance is freed in some way, either by using a consuming function or
///   by explicitly calling `sp_command_free`.
#[no_mangle]
pub unsafe extern "C" fn sp_command_hard_reset() -> *mut SPCommand {
    let result = Box::into_raw(Box::new(SPCommand(servicepoint::Command::HardReset)));
    assert!(!result.is_null());
    result
}

/// A yet-to-be-tested command.
///
/// Returns: a new `Command::FadeOut` instance. Will never return NULL.
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - the returned [SPCommand] instance is freed in some way, either by using a consuming function or
///   by explicitly calling `sp_command_free`.
#[no_mangle]
pub unsafe extern "C" fn sp_command_fade_out() -> *mut SPCommand {
    let result = Box::into_raw(Box::new(SPCommand(servicepoint::Command::FadeOut)));
    assert!(!result.is_null());
    result
}

/// Set the brightness of all tiles to the same value.
///
/// Returns: a new [Command::Brightness] instance. Will never return NULL.
///
/// # Panics
///
/// - When the provided brightness value is out of range (0-11).
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - the returned [SPCommand] instance is freed in some way, either by using a consuming function or
///   by explicitly calling `sp_command_free`.
#[no_mangle]
pub unsafe extern "C" fn sp_command_brightness(
    brightness: u8,
) -> *mut SPCommand {
    let brightness =
        Brightness::try_from(brightness).expect("invalid brightness");
    let result = Box::into_raw(Box::new(SPCommand(servicepoint::Command::Brightness(
        brightness,
    ))));
    assert!(!result.is_null());
    result
}

/// Set the brightness of individual tiles in a rectangular area of the display.
///
/// The passed [SPBrightnessGrid] gets consumed.
///
/// Returns: a new [Command::CharBrightness] instance. Will never return NULL.
///
/// # Panics
///
/// - when `grid` is NULL
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - `grid` points to a valid instance of [SPBrightnessGrid]
/// - `grid` is not used concurrently or after this call
/// - the returned [SPCommand] instance is freed in some way, either by using a consuming function or
///   by explicitly calling `sp_command_free`.
#[no_mangle]
pub unsafe extern "C" fn sp_command_char_brightness(
    x: usize,
    y: usize,
    grid: *mut SPBrightnessGrid,
) -> *mut SPCommand {
    assert!(!grid.is_null());
    let byte_grid = *Box::from_raw(grid);
    let result = Box::into_raw(Box::new(SPCommand(servicepoint::Command::CharBrightness(
        Origin::new(x, y),
        byte_grid.0,
    ))));
    assert!(!result.is_null());
    result
}

/// Set pixel data starting at the pixel offset on screen.
///
/// The screen will continuously overwrite more pixel data without regarding the offset, meaning
/// once the starting row is full, overwriting will continue on column 0.
///
/// The contained [SPBitVec] is always uncompressed.
///
/// The passed [SPBitVec] gets consumed.
///
/// Returns: a new [Command::BitmapLinear] instance. Will never return NULL.
///
/// # Panics
///
/// - when `bit_vec` is null
/// - when `compression_code` is not a valid value
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - `bit_vec` points to a valid instance of [SPBitVec]
/// - `bit_vec` is not used concurrently or after this call
/// - `compression` matches one of the allowed enum values
/// - the returned [SPCommand] instance is freed in some way, either by using a consuming function or
///   by explicitly calling `sp_command_free`.
#[no_mangle]
pub unsafe extern "C" fn sp_command_bitmap_linear(
    offset: usize,
    bit_vec: *mut SPBitVec,
    compression: SPCompressionCode,
) -> *mut SPCommand {
    assert!(!bit_vec.is_null());
    let bit_vec = *Box::from_raw(bit_vec);
    let result = Box::into_raw(Box::new(SPCommand(servicepoint::Command::BitmapLinear(
        offset,
        bit_vec.into(),
        compression.try_into().expect("invalid compression code"),
    ))));
    assert!(!result.is_null());
    result
}

/// Set pixel data according to an and-mask starting at the offset.
///
/// The screen will continuously overwrite more pixel data without regarding the offset, meaning
/// once the starting row is full, overwriting will continue on column 0.
///
/// The contained [SPBitVec] is always uncompressed.
///
/// The passed [SPBitVec] gets consumed.
///
/// Returns: a new [Command::BitmapLinearAnd] instance. Will never return NULL.
///
/// # Panics
///
/// - when `bit_vec` is null
/// - when `compression_code` is not a valid value
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - `bit_vec` points to a valid instance of [SPBitVec]
/// - `bit_vec` is not used concurrently or after this call
/// - `compression` matches one of the allowed enum values
/// - the returned [SPCommand] instance is freed in some way, either by using a consuming function or
///   by explicitly calling `sp_command_free`.
#[no_mangle]
pub unsafe extern "C" fn sp_command_bitmap_linear_and(
    offset: usize,
    bit_vec: *mut SPBitVec,
    compression: SPCompressionCode,
) -> *mut SPCommand {
    assert!(!bit_vec.is_null());
    let bit_vec = *Box::from_raw(bit_vec);
    let result = Box::into_raw(Box::new(SPCommand(servicepoint::Command::BitmapLinearAnd(
        offset,
        bit_vec.into(),
        compression.try_into().expect("invalid compression code"),
    ))));
    assert!(!result.is_null());
    result
}

/// Set pixel data according to an or-mask starting at the offset.
///
/// The screen will continuously overwrite more pixel data without regarding the offset, meaning
/// once the starting row is full, overwriting will continue on column 0.
///
/// The contained [SPBitVec] is always uncompressed.
///
/// The passed [SPBitVec] gets consumed.
///
/// Returns: a new [Command::BitmapLinearOr] instance. Will never return NULL.
///
/// # Panics
///
/// - when `bit_vec` is null
/// - when `compression_code` is not a valid value
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - `bit_vec` points to a valid instance of [SPBitVec]
/// - `bit_vec` is not used concurrently or after this call
/// - `compression` matches one of the allowed enum values
/// - the returned [SPCommand] instance is freed in some way, either by using a consuming function or
///   by explicitly calling `sp_command_free`.
#[no_mangle]
pub unsafe extern "C" fn sp_command_bitmap_linear_or(
    offset: usize,
    bit_vec: *mut SPBitVec,
    compression: SPCompressionCode,
) -> *mut SPCommand {
    assert!(!bit_vec.is_null());
    let bit_vec = *Box::from_raw(bit_vec);
    let result = Box::into_raw(Box::new(SPCommand(servicepoint::Command::BitmapLinearOr(
        offset,
        bit_vec.into(),
        compression.try_into().expect("invalid compression code"),
    ))));
    assert!(!result.is_null());
    result
}

/// Set pixel data according to a xor-mask starting at the offset.
///
/// The screen will continuously overwrite more pixel data without regarding the offset, meaning
/// once the starting row is full, overwriting will continue on column 0.
///
/// The contained [SPBitVec] is always uncompressed.
///
/// The passed [SPBitVec] gets consumed.
///
/// Returns: a new [Command::BitmapLinearXor] instance. Will never return NULL.
///
/// # Panics
///
/// - when `bit_vec` is null
/// - when `compression_code` is not a valid value
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - `bit_vec` points to a valid instance of [SPBitVec]
/// - `bit_vec` is not used concurrently or after this call
/// - `compression` matches one of the allowed enum values
/// - the returned [SPCommand] instance is freed in some way, either by using a consuming function or
///   by explicitly calling `sp_command_free`.
#[no_mangle]
pub unsafe extern "C" fn sp_command_bitmap_linear_xor(
    offset: usize,
    bit_vec: *mut SPBitVec,
    compression: SPCompressionCode,
) -> *mut SPCommand {
    assert!(!bit_vec.is_null());
    let bit_vec = *Box::from_raw(bit_vec);
    let result = Box::into_raw(Box::new(SPCommand(servicepoint::Command::BitmapLinearXor(
        offset,
        bit_vec.into(),
        compression.try_into().expect("invalid compression code"),
    ))));
    assert!(!result.is_null());
    result
}

/// Show text on the screen.
///
/// The passed [SPCp437Grid] gets consumed.
///
/// Returns: a new [Command::Cp437Data] instance. Will never return NULL.
///
/// # Panics
///
/// - when `grid` is null
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - `grid` points to a valid instance of [SPCp437Grid]
/// - `grid` is not used concurrently or after this call
/// - the returned [SPCommand] instance is freed in some way, either by using a consuming function or
///   by explicitly calling `sp_command_free`.
#[no_mangle]
pub unsafe extern "C" fn sp_command_cp437_data(
    x: usize,
    y: usize,
    grid: *mut SPCp437Grid,
) -> *mut SPCommand {
    assert!(!grid.is_null());
    let grid = *Box::from_raw(grid);
    let result = Box::into_raw(Box::new(SPCommand(servicepoint::Command::Cp437Data(
        Origin::new(x, y),
        grid.0,
    ))));
    assert!(!result.is_null());
    result
}

/// Sets a window of pixels to the specified values.
///
/// The passed [SPBitmap] gets consumed.
///
/// Returns: a new [Command::BitmapLinearWin] instance. Will never return NULL.
///
/// # Panics
///
/// - when `bitmap` is null
/// - when `compression_code` is not a valid value
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - `bitmap` points to a valid instance of [SPBitmap]
/// - `bitmap` is not used concurrently or after this call
/// - `compression` matches one of the allowed enum values
/// - the returned [SPCommand] instance is freed in some way, either by using a consuming function or
///   by explicitly calling `sp_command_free`.
#[no_mangle]
pub unsafe extern "C" fn sp_command_bitmap_linear_win(
    x: usize,
    y: usize,
    bitmap: *mut SPBitmap,
    compression_code: SPCompressionCode,
) -> *mut SPCommand {
    assert!(!bitmap.is_null());
    let byte_grid = (*Box::from_raw(bitmap)).0;
    let result = Box::into_raw(Box::new(SPCommand(servicepoint::Command::BitmapLinearWin(
        Origin::new(x, y),
        byte_grid,
        compression_code
            .try_into()
            .expect("invalid compression code"),
    ))));
    assert!(!result.is_null());
    result
}

/// Deallocates a [SPCommand].
///
/// # Examples
///
/// ```C
/// SPCommand c = sp_command_clear();
/// sp_command_free(c);
/// ```
///
/// # Panics
///
/// - when `command` is NULL
///
/// # Safety
///
/// The caller has to make sure that:
///
/// - `command` points to a valid [SPCommand]
/// - `command` is not used concurrently or after this call
/// - `command` was not passed to another consuming function, e.g. to create a [SPPacket]
#[no_mangle]
pub unsafe extern "C" fn sp_command_free(command: *mut SPCommand) {
    assert!(!command.is_null());
    _ = Box::from_raw(command);
}