//! Software Keyboard applet.
//!
//! This applet opens a virtual keyboard on the console's bottom screen which lets the user write UTF-16 valid text.
#![doc(alias = "keyboard")]

use crate::services::{apt::Apt, gfx::Gfx};
use ctru_sys::{
    aptLaunchLibraryApplet, aptSetMessageCallback, envGetAptAppId, svcCloseHandle,
    svcCreateMemoryBlock, APT_SendParameter, SwkbdButton, SwkbdDictWord, SwkbdLearningData,
    SwkbdState, SwkbdStatusData, APPID_SOFTWARE_KEYBOARD, APTCMD_MESSAGE, NS_APPID,
};

use bitflags::bitflags;

use std::borrow::Cow;
use std::fmt::Display;
use std::iter::once;
use std::str;

type CallbackFunction = dyn Fn(&str) -> (CallbackResult, Option<Cow<'static, str>>);

/// Configuration structure to setup the Software Keyboard applet.
#[doc(alias = "SwkbdState")]
pub struct SoftwareKeyboard {
    state: Box<SwkbdState>,
    filter_callback: Option<Box<CallbackFunction>>,
    initial_text: Option<Cow<'static, str>>,
}

/// Configuration structure to setup the Parental Lock applet.
///
/// Internally, the Parental Lock is just a different kind of [`SoftwareKeyboard`].
#[doc(alias = "SwkbdState")]
#[derive(Clone)]
pub struct ParentalLock {
    state: Box<SwkbdState>,
}

/// The type of keyboard used by the [`SoftwareKeyboard`].
///
/// Can be set with [`SoftwareKeyboard::new()`]
#[doc(alias = "SwkbdType")]
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
#[repr(u8)]
pub enum Kind {
    /// Normal keyboard composed of several pages (QWERTY, accents, symbols, mobile).
    Normal = ctru_sys::SWKBD_TYPE_NORMAL,
    /// Only QWERTY keyboard.
    Qwerty = ctru_sys::SWKBD_TYPE_QWERTY,
    /// Only number pad.
    Numpad = ctru_sys::SWKBD_TYPE_NUMPAD,
    /// On JPN systems: a keyboard without japanese input capabilities.
    ///
    /// On any other region: same as [`Normal`](Kind::Normal).
    Western = ctru_sys::SWKBD_TYPE_WESTERN,
}

/// The type of result returned by a custom filter callback.
///
/// The custom callback can be set using [`SoftwareKeyboard::set_filter_callback()`].
#[doc(alias = "SwkbdCallbackResult")]
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
#[repr(u8)]
pub enum CallbackResult {
    /// The callback yields a positive result.
    Ok = ctru_sys::SWKBD_CALLBACK_OK,
    /// The callback finds the input invalid, but lets the user try again.
    Retry = ctru_sys::SWKBD_CALLBACK_CONTINUE,
    /// The callback finds the input invalid and closes the Software Keyboard view.
    Close = ctru_sys::SWKBD_CALLBACK_CLOSE,
}

/// Represents which button the user pressed to close the [`SoftwareKeyboard`].
///
/// Button text and behaviour can be customized with [`SoftwareKeyboard::configure_button()`].
#[doc(alias = "SwkbdButton")]
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
#[repr(u8)]
pub enum Button {
    /// Left button. Usually corresponds to "Cancel".
    Left = ctru_sys::SWKBD_BUTTON_LEFT,
    /// Middle button. Usually corresponds to "I Forgot".
    Middle = ctru_sys::SWKBD_BUTTON_MIDDLE,
    /// Right button. Usually corresponds to "OK".
    Right = ctru_sys::SWKBD_BUTTON_RIGHT,
}

/// Represents the password mode to conceal the input text for the [`SoftwareKeyboard`].
///
/// Can be set using [`SoftwareKeyboard::set_password_mode()`].
#[doc(alias = "SwkbdPasswordMode")]
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
#[repr(u8)]
pub enum PasswordMode {
    /// The input text will not be concealed.
    None = ctru_sys::SWKBD_PASSWORD_NONE,
    /// The input text will be concealed immediately after typing.
    Hide = ctru_sys::SWKBD_PASSWORD_HIDE,
    /// The input text will be concealed a second after typing.
    HideDelay = ctru_sys::SWKBD_PASSWORD_HIDE_DELAY,
}

/// Configuration to setup the on-screen buttons to exit the [`SoftwareKeyboard`] prompt.
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
#[repr(i32)]
pub enum ButtonConfig {
    /// 1 Button: considered the right button.
    Right = 1,
    /// 2 Buttons: left and right buttons.
    LeftRight = 2,
    /// 3 Buttons: left, middle and right buttons.
    LeftMiddleRight = 3,
}

/// Error returned by an unsuccessful [`SoftwareKeyboard::launch()`].
#[doc(alias = "SwkbdResult")]
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
#[repr(i8)]
pub enum Error {
    /// Invalid parameters given to the [`SoftwareKeyboard`] configuration.
    InvalidParameters = ctru_sys::SWKBD_INVALID_INPUT,
    /// [`SoftwareKeyboard`] ran out of memory.
    OutOfMem = ctru_sys::SWKBD_OUTOFMEM,
    /// Home button was pressed while [`SoftwareKeyboard`] was running.
    HomePressed = ctru_sys::SWKBD_HOMEPRESSED,
    /// Reset button was pressed while [`SoftwareKeyboard`] was running.
    ResetPressed = ctru_sys::SWKBD_RESETPRESSED,
    /// Power button was pressed while [`SoftwareKeyboard`] was running.
    PowerPressed = ctru_sys::SWKBD_POWERPRESSED,
    /// The parental lock PIN was correct.
    ///
    /// This variant should never be returned by normal operations made using this module,
    /// and is listed here only for compatibility purposes.
    /// Refer to the return value of [`ParentalLock::launch()`] to confirm the outcome
    /// of the Parental Lock PIN operation.
    ParentalOk = ctru_sys::SWKBD_PARENTAL_OK,
    /// The parental lock PIN was incorrect.
    ///
    /// Refer to the return value of [`ParentalLock::launch()`] to confirm the outcome
    /// of the Parental Lock PIN operation.
    ParentalFail = ctru_sys::SWKBD_PARENTAL_FAIL,
    /// Input triggered the filter.
    ///
    /// You can have a look at [`Filters`] to activate custom filters.
    BannedInput = ctru_sys::SWKBD_BANNED_INPUT,
    /// An on-screen button was pressed to exit the prompt.
    ButtonPressed = ctru_sys::SWKBD_D0_CLICK,
}

/// Restrictions to enforce rules on the keyboard input.
///
/// See [`SoftwareKeyboard::set_validation()`]
#[doc(alias = "SwkbdValidInput")]
#[derive(Copy, Clone, Debug, PartialEq, Eq)]
#[repr(u8)]
pub enum ValidInput {
    /// All inputs are accepted.
    Anything = ctru_sys::SWKBD_ANYTHING,
    /// Empty inputs are not accepted.
    NotEmpty = ctru_sys::SWKBD_NOTEMPTY,
    /// Blank inputs (consisting only of whitespaces) are not accepted.
    NotBlank = ctru_sys::SWKBD_NOTBLANK,
    /// Neither empty inputs nor blank inputs are accepted.
    NotEmptyNotBlank = ctru_sys::SWKBD_NOTEMPTY_NOTBLANK,
    /// Input must have a fixed length. Maximum length can be specified with [`SoftwareKeyboard::set_max_text_len()`];
    FixedLen = ctru_sys::SWKBD_FIXEDLEN,
}

bitflags! {
    /// Special features that can be activated via [`SoftwareKeyboard::set_features()`].
    #[derive(PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Clone, Copy)]
    pub struct Features: u16 {
        /// Darken top screen while the [`SoftwareKeyboard`] is active.
        const DARKEN_TOP_SCREEN = ctru_sys::SWKBD_DARKEN_TOP_SCREEN;
        /// Enable predictive input (necessary for Kanji on JPN consoles).
        const PREDICTIVE_INPUT  = ctru_sys::SWKBD_PREDICTIVE_INPUT;
        /// Enable multiline input.
        const MULTILINE         = ctru_sys::SWKBD_MULTILINE;
        /// Enable fixed-width mode.
        const FIXED_WIDTH       = ctru_sys::SWKBD_FIXED_WIDTH;
        /// Allow the usage of the Home Button while the [`SoftwareKeyboard`] is running.
        const ALLOW_HOME        = ctru_sys::SWKBD_ALLOW_HOME;
        /// Allow the usage of the Reset Button while the [`SoftwareKeyboard`] is running.
        const ALLOW_RESET       = ctru_sys::SWKBD_ALLOW_RESET;
        /// Allow the usage of the Power Button while the [`SoftwareKeyboard`] is running.
        const ALLOW_POWER       = ctru_sys::SWKBD_ALLOW_POWER;
        /// Default to the QWERTY page when the [`SoftwareKeyboard`] is shown.
        const DEFAULT_QWERTY    = ctru_sys::SWKBD_DEFAULT_QWERTY;
    }

    /// Availble filters to disallow some types of input for the [`SoftwareKeyboard`].
    ///
    /// See [`SoftwareKeyboard::set_validation()`]
    #[derive(PartialEq, Eq, PartialOrd, Ord, Hash, Debug, Clone, Copy)]
    pub struct Filters: u8 {
        /// Disallow the usage of numerical digits.
        ///
        /// The maximum number of digits that are allowed to be used while this filter is active
        /// can be configured with [`SoftwareKeyboard::set_max_digits()`] (default is 0).
        const DIGITS    = ctru_sys::SWKBD_FILTER_DIGITS;
        /// Disallow the usage of the "at" (@) sign.
        const AT        = ctru_sys::SWKBD_FILTER_AT;
        /// Disallow the usage of the "percent" (%) sign.
        const PERCENT   = ctru_sys::SWKBD_FILTER_PERCENT;
        /// Disallow the usage of the "backslash" (\) sign.
        const BACKSLASH = ctru_sys::SWKBD_FILTER_BACKSLASH;
        /// Disallow the use of profanity via Nintendo's profanity filter.
        const PROFANITY = ctru_sys::SWKBD_FILTER_PROFANITY;
    }
}

// Internal book-keeping struct used to send data to `aptSetMessageCallback` when calling the software keyboard.
#[derive(Copy, Clone)]
struct MessageCallbackData {
    filter_callback: *const Box<CallbackFunction>,
    swkbd_shared_mem_ptr: *mut libc::c_void,
}

impl SoftwareKeyboard {
    /// Initialize a new configuration for the Software Keyboard applet depending on how many "exit" buttons are available to the user (1, 2 or 3).
    ///
    /// # Example
    ///
    /// ```
    /// # let _runner = test_runner::GdbRunner::default();
    /// # fn main() {
    /// #
    /// use ctru::applets::swkbd::{SoftwareKeyboard, ButtonConfig, Kind};
    ///
    /// // Standard keyboard. Equivalent to `SoftwareKeyboard::default()`.
    /// let keyboard = SoftwareKeyboard::new(Kind::Normal, ButtonConfig::LeftRight);
    ///
    /// // Numpad (with only the "confirm" button).
    /// let keyboard = SoftwareKeyboard::new(Kind::Numpad, ButtonConfig::Right);
    /// #
    /// # }
    #[doc(alias = "swkbdInit")]
    pub fn new(keyboard_type: Kind, buttons: ButtonConfig) -> Self {
        unsafe {
            let mut state = Box::<SwkbdState>::default();
            ctru_sys::swkbdInit(state.as_mut(), keyboard_type.into(), buttons.into(), -1);
            Self {
                state,
                filter_callback: None,
                initial_text: None,
            }
        }
    }

    /// Launches the applet based on the given configuration and returns a string containing the text input.
    ///
    /// # Example
    ///
    /// ```
    /// # let _runner = test_runner::GdbRunner::default();
    /// # use std::error::Error;
    /// # fn main() -> Result<(), Box<dyn Error>> {
    /// # use ctru::services::{apt::Apt, gfx::Gfx};
    /// #
    /// # let gfx = Gfx::new().unwrap();
    /// # let apt = Apt::new().unwrap();
    /// #
    /// use ctru::applets::swkbd::SoftwareKeyboard;
    /// let mut keyboard = SoftwareKeyboard::default();
    ///
    /// let (text, button) = keyboard.launch(&apt, &gfx)?;
    /// #
    /// # Ok(())
    /// # }
    /// ```
    #[doc(alias = "swkbdInputText")]
    pub fn launch(&mut self, apt: &Apt, gfx: &Gfx) -> Result<(String, Button), Error> {
        let mut output = String::new();

        match self.swkbd_input_text(&mut output, apt, gfx) {
            ctru_sys::SWKBD_BUTTON_NONE => Err(self.state.result.into()),
            ctru_sys::SWKBD_BUTTON_LEFT => Ok((output, Button::Left)),
            ctru_sys::SWKBD_BUTTON_MIDDLE => Ok((output, Button::Middle)),
            ctru_sys::SWKBD_BUTTON_RIGHT => Ok((output, Button::Right)),
            _ => unreachable!(),
        }
    }

    /// Set special features for this keyboard.
    ///
    /// # Example
    ///
    /// ```
    /// # let _runner = test_runner::GdbRunner::default();
    /// # fn main() {
    /// #
    /// use ctru::applets::swkbd::{SoftwareKeyboard, Features};
    ///
    /// let mut keyboard = SoftwareKeyboard::default();
    ///
    /// let features = Features::DARKEN_TOP_SCREEN & Features::MULTILINE;
    /// keyboard.set_features(features);
    /// #
    /// # }
    #[doc(alias = "swkbdSetFeatures")]
    pub fn set_features(&mut self, features: Features) {
        unsafe { ctru_sys::swkbdSetFeatures(self.state.as_mut(), features.bits().into()) }
    }

    /// Configure input validation for this keyboard.
    ///
    /// # Example
    ///
    /// ```
    /// # let _runner = test_runner::GdbRunner::default();
    /// # fn main() {
    /// #
    /// use ctru::applets::swkbd::{SoftwareKeyboard, ValidInput, Filters};
    /// let mut keyboard = SoftwareKeyboard::default();
    ///
    /// // Disallow empty or blank input.
    /// let validation = ValidInput::NotEmptyNotBlank;
    ///
    /// // Disallow the use of numerical digits and profanity.
    /// let filters = Filters::DIGITS & Filters::PROFANITY;
    /// keyboard.set_validation(validation, filters);
    /// #
    /// # }
    pub fn set_validation(&mut self, validation: ValidInput, filters: Filters) {
        self.state.valid_input = validation.into();
        self.state.filter_flags = filters.bits().into();
    }

    /// Configure a custom filtering function to validate the input.
    ///
    /// The callback function must return a [`CallbackResult`] and the error message to display when the input is invalid.
    ///
    /// # Notes
    ///
    /// Passing [`None`] will unbind the custom filter callback.
    ///
    /// The error message returned by the callback should be shorter than `256` characters, otherwise it will be truncated.
    ///
    /// # Example
    ///
    /// ```
    /// # let _runner = test_runner::GdbRunner::default();
    /// # fn main() {
    /// #
    /// use std::borrow::Cow;
    /// use ctru::applets::swkbd::{SoftwareKeyboard, CallbackResult};
    ///
    /// let mut keyboard = SoftwareKeyboard::default();
    ///
    /// keyboard.set_filter_callback(Some(Box::new(move |str| {
    ///     if str.contains("boo") {
    ///         return (CallbackResult::Retry, Some("Ah, you scared me!".into()));
    ///     }
    ///
    ///     (CallbackResult::Ok, None)
    /// })));
    /// #
    /// # }
    pub fn set_filter_callback(&mut self, callback: Option<Box<CallbackFunction>>) {
        self.filter_callback = callback;
    }

    /// Configure the maximum number of digits that can be entered in the keyboard when the [`Filters::DIGITS`] flag is enabled.
    ///
    /// # Example
    ///
    /// ```
    /// # let _runner = test_runner::GdbRunner::default();
    /// # fn main() {
    /// #
    /// use ctru::applets::swkbd::{SoftwareKeyboard, ValidInput, Filters};
    /// let mut keyboard = SoftwareKeyboard::default();
    ///
    /// // Disallow empty or blank input.
    /// let validation = ValidInput::NotEmptyNotBlank;
    ///
    /// // Disallow the use of numerical digits. This filter is customizable thanks to `set_max_digits`.
    /// let filters = Filters::DIGITS;
    /// keyboard.set_validation(validation, filters);
    ///
    /// // No more than 3 numbers are accepted.
    /// keyboard.set_max_digits(3);
    /// #
    /// # }
    pub fn set_max_digits(&mut self, digits: u16) {
        self.state.max_digits = digits;
    }

    /// Set the initial text for this software keyboard.
    ///
    /// The initial text is the text already written when you open the software keyboard.
    ///
    /// # Notes
    ///
    /// Passing [`None`] will clear the initial text.
    ///
    /// # Example
    ///
    /// ```
    /// # let _runner = test_runner::GdbRunner::default();
    /// # fn main() {
    /// #
    /// use ctru::applets::swkbd::SoftwareKeyboard;
    /// let mut keyboard = SoftwareKeyboard::default();
    ///
    /// keyboard.set_initial_text(Some("Write here what you like!".into()));
    /// #
    /// # }
    #[doc(alias = "swkbdSetInitialText")]
    pub fn set_initial_text(&mut self, text: Option<Cow<'static, str>>) {
        self.initial_text = text;
    }

    /// Set the hint text for this software keyboard.
    ///
    /// The hint text is the text shown in gray before any text gets written in the input box.
    ///
    /// # Notes
    ///
    /// Passing [`None`] will clear the hint text.
    ///
    /// The hint text will be converted to UTF-16 when passed to the software keyboard, and the text will be truncated
    /// if the length exceeds 64 code units after conversion.
    ///
    /// # Example
    ///
    /// ```
    /// # let _runner = test_runner::GdbRunner::default();
    /// # fn main() {
    /// #
    /// use ctru::applets::swkbd::SoftwareKeyboard;
    /// let mut keyboard = SoftwareKeyboard::default();
    ///
    /// keyboard.set_hint_text(Some("Write here what you like!"));
    /// #
    /// # }
    #[doc(alias = "swkbdSetHintText")]
    pub fn set_hint_text(&mut self, text: Option<&str>) {
        if let Some(text) = text {
            for (idx, code_unit) in text
                .encode_utf16()
                .take(self.state.hint_text.len() - 1)
                .chain(once(0))
                .enumerate()
            {
                self.state.hint_text[idx] = code_unit;
            }
        } else {
            self.state.hint_text[0] = 0;
        }
    }

    /// Set a password mode for this software keyboard.
    ///
    /// Depending on the selected mode the input text will be concealed.
    ///
    /// # Example
    ///
    /// ```
    /// # let _runner = test_runner::GdbRunner::default();
    /// # fn main() {
    /// #
    /// use ctru::applets::swkbd::{SoftwareKeyboard, PasswordMode};
    /// let mut keyboard = SoftwareKeyboard::default();
    ///
    /// keyboard.set_password_mode(PasswordMode::Hide);
    /// #
    /// # }
    #[doc(alias = "swkbdSetPasswordMode")]
    pub fn set_password_mode(&mut self, mode: PasswordMode) {
        unsafe {
            ctru_sys::swkbdSetPasswordMode(self.state.as_mut(), mode as _);
        }
    }

    /// Set the 2 custom characters to add to the keyboard while using [`Kind::Numpad`].
    ///
    /// These characters will appear in their own buttons right next to the `0` key.
    ///
    /// # Notes
    ///
    /// If [`None`] is passed as either key, that button will not be shown to the user.
    ///
    /// # Example
    ///
    /// ```
    /// # let _runner = test_runner::GdbRunner::default();
    /// # fn main() {
    /// #
    /// use ctru::applets::swkbd::{SoftwareKeyboard, Kind, ButtonConfig};
    /// let mut keyboard = SoftwareKeyboard::new(Kind::Numpad, ButtonConfig::LeftRight);
    ///
    /// keyboard.set_numpad_keys(Some('#'), Some('.'));
    ///
    /// // The right numpad key will not be shown.
    /// keyboard.set_numpad_keys(Some('!'), None);
    /// #
    /// # }
    #[doc(alias = "swkbdSetNumpadKeys")]
    pub fn set_numpad_keys(&mut self, left_key: Option<char>, right_key: Option<char>) {
        let mut keys = (0, 0);

        if let Some(k) = left_key {
            keys.0 = k as i32;
        }

        if let Some(k) = right_key {
            keys.1 = k as i32;
        }

        unsafe {
            ctru_sys::swkbdSetNumpadKeys(self.state.as_mut(), keys.0, keys.1);
        }
    }

    /// Configure the look and behavior of a button for this keyboard.
    ///
    /// # Arguments
    ///
    /// - `button` - the [`Button`] to be configured based on the position.
    /// - `text` - the text displayed in the button.
    /// - `submit` - whether pressing the button will accept the keyboard's input or discard it.
    ///
    /// # Example
    ///
    /// ```
    /// # let _runner = test_runner::GdbRunner::default();
    /// # fn main() {
    /// #
    /// use ctru::applets::swkbd::{SoftwareKeyboard, Button, ButtonConfig, Kind};
    ///
    /// // We create a `SoftwareKeyboard` with left and right buttons.
    /// let mut keyboard = SoftwareKeyboard::new(Kind::Normal, ButtonConfig::LeftRight);
    ///
    /// // Set the left button text to "Cancel" and pressing it will NOT return the user's input.
    /// keyboard.configure_button(Button::Left, "Cancel", false);
    ///
    /// // Set the right button text to "Ok" and pressing it will return the user's input.
    /// keyboard.configure_button(Button::Right, "Ok", true);
    /// #
    /// # }
    #[doc(alias = "swkbdSetButton")]
    pub fn configure_button(&mut self, button: Button, text: &str, submit: bool) {
        let button_text = &mut self.state.button_text[button as usize];

        for (idx, code_unit) in text
            .encode_utf16()
            .take(button_text.len() - 1)
            .chain(once(0))
            .enumerate()
        {
            button_text[idx] = code_unit;
        }

        self.state.button_submits_text[button as usize] = submit;
    }

    /// Configure the maximum number of UTF-16 code units that can be entered into the software
    /// keyboard. By default the limit is `65000` code units.
    ///
    /// # Notes
    ///
    /// This action will overwrite any previously submitted [`ValidInput`] validation.
    ///
    /// Keyboard input is converted from UTF-16 to UTF-8 before being handed to Rust,
    /// so this code point limit does not necessarily equal the max number of UTF-8 code points
    /// receivable by [`SoftwareKeyboard::launch()`].
    ///
    /// # Example
    ///
    /// ```
    /// # let _runner = test_runner::GdbRunner::default();
    /// # fn main() {
    /// #
    /// use ctru::applets::swkbd::{SoftwareKeyboard, Button, Kind};
    /// let mut keyboard = SoftwareKeyboard::default();
    ///
    /// // Set the maximum text length to 18 UTF-16 code units.
    /// keyboard.set_max_text_len(18);
    /// #
    /// # }
    pub fn set_max_text_len(&mut self, len: u16) {
        self.state.max_text_len = len;

        // Activate the specific validation rule for maximum length.
        self.state.valid_input = ValidInput::FixedLen.into();
    }

    // A reimplementation of `swkbdInputText` from `libctru/source/applets/swkbd.c`. Allows us to fix various
    // API nits and get rid of awkward type conversions when interacting with the Software Keyboard.
    fn swkbd_input_text(&mut self, output: &mut String, _apt: &Apt, _gfx: &Gfx) -> SwkbdButton {
        use ctru_sys::{
            MEMPERM_READ, MEMPERM_WRITE, R_FAILED, SWKBD_BUTTON_LEFT, SWKBD_BUTTON_MIDDLE,
            SWKBD_BUTTON_NONE, SWKBD_BUTTON_RIGHT, SWKBD_D0_CLICK, SWKBD_D1_CLICK0,
            SWKBD_D1_CLICK1, SWKBD_D2_CLICK0, SWKBD_D2_CLICK1, SWKBD_D2_CLICK2,
            SWKBD_FILTER_CALLBACK, SWKBD_OUTOFMEM,
        };

        let swkbd = self.state.as_mut();
        let extra = unsafe { swkbd.__bindgen_anon_1.extra };

        // Calculate shared mem size
        let mut shared_mem_size = 0;

        shared_mem_size += (std::mem::size_of::<u16>() * (swkbd.max_text_len as usize + 1))
            .next_multiple_of(std::mem::size_of::<usize>());

        let dict_off = shared_mem_size;

        shared_mem_size += (std::mem::size_of::<SwkbdDictWord>() * swkbd.dict_word_count as usize)
            .next_multiple_of(std::mem::size_of::<usize>());

        let status_off = shared_mem_size;

        shared_mem_size += if swkbd.initial_learning_offset >= 0 {
            std::mem::size_of::<SwkbdStatusData>()
        } else {
            0
        };

        let learning_off = shared_mem_size;

        shared_mem_size += if swkbd.initial_learning_offset >= 0 {
            std::mem::size_of::<SwkbdLearningData>()
        } else {
            0
        };

        if swkbd.save_state_flags & (1 << 0) != 0 {
            swkbd.status_offset = shared_mem_size as _;
            shared_mem_size += std::mem::size_of::<SwkbdStatusData>();
        }

        if swkbd.save_state_flags & (1 << 1) != 0 {
            swkbd.learning_offset = shared_mem_size as _;
            shared_mem_size += std::mem::size_of::<SwkbdLearningData>();
        }

        shared_mem_size = shared_mem_size.next_multiple_of(0x1000);

        swkbd.shared_memory_size = shared_mem_size;

        // Allocate shared mem
        let swkbd_shared_mem_ptr = unsafe { libc::memalign(0x1000, shared_mem_size) };

        let mut swkbd_shared_mem_handle = 0;

        if swkbd_shared_mem_ptr.is_null() {
            swkbd.result = SWKBD_OUTOFMEM;
            return SWKBD_BUTTON_NONE;
        }

        let res = unsafe {
            svcCreateMemoryBlock(
                &mut swkbd_shared_mem_handle,
                swkbd_shared_mem_ptr as _,
                shared_mem_size as _,
                MEMPERM_READ | MEMPERM_WRITE,
                MEMPERM_READ | MEMPERM_WRITE,
            )
        };

        if R_FAILED(res) {
            unsafe {
                libc::free(swkbd_shared_mem_ptr);
                swkbd.result = SWKBD_OUTOFMEM;
                return SWKBD_BUTTON_NONE;
            }
        }

        // Copy stuff to shared mem
        if let Some(initial_text) = self.initial_text.as_deref() {
            swkbd.initial_text_offset = 0;

            let mut initial_text_cursor = swkbd_shared_mem_ptr.cast();

            for code_unit in initial_text
                .encode_utf16()
                .take(swkbd.max_text_len as _)
                .chain(once(0))
            {
                unsafe {
                    *initial_text_cursor = code_unit;
                    initial_text_cursor = initial_text_cursor.add(1);
                }
            }
        }

        if !extra.dict.is_null() {
            swkbd.dict_offset = dict_off as _;
            unsafe {
                std::ptr::copy_nonoverlapping(
                    extra.dict,
                    swkbd_shared_mem_ptr.add(dict_off).cast(),
                    swkbd.dict_word_count as _,
                )
            };
        }

        if swkbd.initial_status_offset >= 0 {
            swkbd.initial_status_offset = status_off as _;
            unsafe {
                std::ptr::copy_nonoverlapping(
                    extra.status_data,
                    swkbd_shared_mem_ptr.add(status_off).cast(),
                    1,
                )
            };
        }

        if swkbd.initial_learning_offset >= 0 {
            swkbd.initial_learning_offset = learning_off as _;
            unsafe {
                std::ptr::copy_nonoverlapping(
                    extra.learning_data,
                    swkbd_shared_mem_ptr.add(learning_off).cast(),
                    1,
                )
            };
        }

        if self.filter_callback.is_some() {
            swkbd.filter_flags |= u32::from(SWKBD_FILTER_CALLBACK);
        } else {
            swkbd.filter_flags &= !u32::from(SWKBD_FILTER_CALLBACK);
        }

        // Launch swkbd
        unsafe {
            swkbd.__bindgen_anon_1.reserved.fill(0);

            // We need to pass a thin pointer to the boxed closure over FFI. Since we know that the message callback will finish before
            // `self` is allowed to be moved again, we can safely use a pointer to the local value contained in `self.filter_callback`
            // The cast here is also sound since the pointer will only be read from if `self.filter_callback.is_some()` returns true.
            let mut data = MessageCallbackData {
                filter_callback: std::ptr::addr_of!(self.filter_callback).cast(),
                swkbd_shared_mem_ptr,
            };

            if self.filter_callback.is_some() {
                aptSetMessageCallback(
                    Some(Self::swkbd_message_callback),
                    std::ptr::addr_of_mut!(data).cast(),
                )
            }

            aptLaunchLibraryApplet(
                APPID_SOFTWARE_KEYBOARD,
                (swkbd as *mut SwkbdState).cast(),
                std::mem::size_of::<SwkbdState>(),
                swkbd_shared_mem_handle,
            );

            if self.filter_callback.is_some() {
                aptSetMessageCallback(None, std::ptr::null_mut());
            }

            let _ = svcCloseHandle(swkbd_shared_mem_handle);
        }

        let button = match swkbd.result {
            SWKBD_D1_CLICK0 | SWKBD_D2_CLICK0 => SWKBD_BUTTON_LEFT,
            SWKBD_D2_CLICK1 => SWKBD_BUTTON_MIDDLE,
            SWKBD_D0_CLICK | SWKBD_D1_CLICK1 | SWKBD_D2_CLICK2 => SWKBD_BUTTON_RIGHT,
            _ => SWKBD_BUTTON_NONE,
        };

        if swkbd.text_length > 0 {
            let text16 = unsafe {
                widestring::Utf16Str::from_slice_unchecked(std::slice::from_raw_parts(
                    swkbd_shared_mem_ptr.add(swkbd.text_offset as _).cast(),
                    swkbd.text_length as _,
                ))
            };

            *output = text16.to_string();
        }

        if swkbd.save_state_flags & (1 << 0) != 0 {
            unsafe {
                std::ptr::copy_nonoverlapping(
                    swkbd_shared_mem_ptr.add(swkbd.status_offset as _).cast(),
                    extra.status_data,
                    1,
                )
            };
        }

        if swkbd.save_state_flags & (1 << 1) != 0 {
            unsafe {
                std::ptr::copy_nonoverlapping(
                    swkbd_shared_mem_ptr.add(swkbd.learning_offset as _).cast(),
                    extra.learning_data,
                    1,
                )
            };
        }

        unsafe { libc::free(swkbd_shared_mem_ptr) };

        button
    }

    // A reimplementation of `swkbdMessageCallback` from `libctru/source/applets/swkbd.c`.
    // This function sets up and then calls the filter callback
    unsafe extern "C" fn swkbd_message_callback(
        user: *mut libc::c_void,
        sender: NS_APPID,
        msg: *mut libc::c_void,
        msg_size: libc::size_t,
    ) {
        if sender != ctru_sys::APPID_SOFTWARE_KEYBOARD
            || msg_size != std::mem::size_of::<SwkbdState>()
        {
            return;
        }

        let swkbd = unsafe { &mut *msg.cast::<SwkbdState>() };
        let data = unsafe { *user.cast::<MessageCallbackData>() };

        let text16 = unsafe {
            widestring::Utf16Str::from_slice_unchecked(std::slice::from_raw_parts(
                data.swkbd_shared_mem_ptr.add(swkbd.text_offset as _).cast(),
                swkbd.text_length as _,
            ))
        };

        let text8 = text16.to_string();

        let filter_callback = unsafe { &**data.filter_callback };

        let (result, retmsg) = filter_callback(&text8);

        swkbd.callback_result = result as _;

        if let Some(msg) = retmsg.as_deref() {
            for (idx, code_unit) in msg
                .encode_utf16()
                .take(swkbd.callback_msg.len() - 1)
                .chain(once(0))
                .enumerate()
            {
                swkbd.callback_msg[idx] = code_unit;
            }
        }

        let _ = unsafe {
            APT_SendParameter(
                envGetAptAppId() as _,
                sender,
                APTCMD_MESSAGE,
                (swkbd as *mut SwkbdState).cast(),
                std::mem::size_of::<SwkbdState>() as _,
                0,
            )
        };
    }
}

impl ParentalLock {
    /// Initialize a new configuration for the Parental Lock applet.
    ///
    /// # Example
    ///
    /// ```
    /// # let _runner = test_runner::GdbRunner::default();
    /// # fn main() {
    /// #
    /// use ctru::applets::swkbd::ParentalLock;
    ///
    /// let parental_lock = ParentalLock::new();
    /// #
    /// # }
    #[doc(alias = "swkbdInit")]
    pub fn new() -> Self {
        unsafe {
            let mut state = Box::<SwkbdState>::default();
            ctru_sys::swkbdInit(state.as_mut(), Kind::Normal.into(), 1, -1);
            ctru_sys::swkbdSetFeatures(state.as_mut(), ctru_sys::SWKBD_PARENTAL.into());
            Self { state }
        }
    }

    /// Launch the Parental Lock applet based on the configuration and return a result depending on whether the operation was successful or not.
    ///
    /// # Example
    ///
    /// ```
    /// # let _runner = test_runner::GdbRunner::default();
    /// # fn main() {
    /// # use ctru::services::{apt::Apt, gfx::Gfx};
    /// #
    /// # let gfx = Gfx::new().unwrap();
    /// # let apt = Apt::new().unwrap();
    /// use ctru::applets::swkbd::{ParentalLock, Error};
    ///
    /// let mut parental_lock = ParentalLock::new();
    ///
    /// match parental_lock.launch(&apt, &gfx) {
    ///     Ok(_) => println!("You can access parental-only features and settings."),
    ///     Err(Error::ParentalFail) => println!("Is a kid trying to access this?"),
    ///     Err(_) => println!("Something wrong happened during the parental lock prompt.")
    /// }
    /// #
    /// # }
    #[doc(alias = "swkbdInputText")]
    pub fn launch(&mut self, _apt: &Apt, _gfx: &Gfx) -> Result<(), Error> {
        unsafe {
            let mut buf = [0; 0];
            ctru_sys::swkbdInputText(self.state.as_mut(), buf.as_mut_ptr(), 0);
            let e = self.state.result.into();

            match e {
                Error::ParentalOk => Ok(()),
                _ => Err(e),
            }
        }
    }
}

/// Creates a new [`SoftwareKeyboard`] configuration set to using a [`Kind::Normal`] keyboard and 2 [`Button`]s.
impl Default for SoftwareKeyboard {
    fn default() -> Self {
        SoftwareKeyboard::new(Kind::Normal, ButtonConfig::LeftRight)
    }
}

impl Default for ParentalLock {
    fn default() -> Self {
        ParentalLock::new()
    }
}

impl Display for Error {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        match self {
            Self::InvalidParameters => write!(
                f,
                "software keyboard was configured with invalid parameters"
            ),
            Self::OutOfMem => write!(f, "software keyboard ran out of memory"),
            Self::HomePressed => {
                write!(f, "home button pressed while software keyboard was running")
            }
            Self::ResetPressed => write!(
                f,
                "reset button pressed while software keyboard was running"
            ),
            Self::PowerPressed => write!(
                f,
                "power button pressed while software keyboard was running"
            ),
            Self::ParentalOk => write!(f, "parental lock pin was correct"),
            Self::ParentalFail => write!(f, "parental lock pin was incorrect"),
            Self::BannedInput => write!(
                f,
                "input given to the software keyboard triggered the active filters"
            ),
            Self::ButtonPressed => write!(f, "on-screen button was pressed to exit the prompt"),
        }
    }
}

impl std::error::Error for Error {}

impl From<ctru_sys::SwkbdResult> for Error {
    fn from(value: ctru_sys::SwkbdResult) -> Self {
        match value {
            ctru_sys::SWKBD_INVALID_INPUT => Error::InvalidParameters,
            ctru_sys::SWKBD_OUTOFMEM => Error::OutOfMem,
            ctru_sys::SWKBD_HOMEPRESSED => Error::HomePressed,
            ctru_sys::SWKBD_RESETPRESSED => Error::ResetPressed,
            ctru_sys::SWKBD_POWERPRESSED => Error::PowerPressed,
            ctru_sys::SWKBD_PARENTAL_OK => Error::ParentalOk,
            ctru_sys::SWKBD_PARENTAL_FAIL => Error::ParentalFail,
            ctru_sys::SWKBD_BANNED_INPUT => Error::BannedInput,
            ctru_sys::SWKBD_D0_CLICK => Error::ButtonPressed,
            ctru_sys::SWKBD_D1_CLICK0 => Error::ButtonPressed,
            ctru_sys::SWKBD_D1_CLICK1 => Error::ButtonPressed,
            ctru_sys::SWKBD_D2_CLICK0 => Error::ButtonPressed,
            ctru_sys::SWKBD_D2_CLICK1 => Error::ButtonPressed,
            ctru_sys::SWKBD_D2_CLICK2 => Error::ButtonPressed,
            _ => unreachable!(),
        }
    }
}

from_impl!(Kind, ctru_sys::SwkbdType);
from_impl!(Button, ctru_sys::SwkbdButton);
from_impl!(Error, ctru_sys::SwkbdResult);
from_impl!(ValidInput, i32);
from_impl!(ValidInput, u32);
from_impl!(ButtonConfig, i32);
from_impl!(PasswordMode, u32);
from_impl!(CallbackResult, u32);