use auth::Authenticate;
use config::{Config, RawConfig};
use libc;
use nitrokey_sys;
use otp::GenerateOtp;
use pws::GetPasswordSafe;
use std::ffi::CString;
use util::{get_last_error, result_from_string, CommandError, CommandStatus};

/// Available Nitrokey models.
#[derive(Debug, PartialEq)]
enum Model {
    /// The Nitrokey Storage.
    Storage,
    /// The Nitrokey Pro.
    Pro,
}

/// A wrapper for a Nitrokey device of unknown type.
///
/// Use the function [`connect`][] to obtain a wrapped instance.  The wrapper implements all traits
/// that are shared between all Nitrokey devices so that the shared functionality can be used
/// without knowing the type of the underlying device.  If you want to use functionality that is
/// not available for all devices, you have to extract the device.
///
/// # Examples
///
/// Authentication with error handling:
///
/// ```no_run
/// use nitrokey::{Authenticate, DeviceWrapper, User};
/// # use nitrokey::CommandError;
///
/// fn perform_user_task(device: &User<DeviceWrapper>) {}
/// fn perform_other_task(device: &DeviceWrapper) {}
///
/// # fn try_main() -> Result<(), CommandError> {
/// let device = nitrokey::connect()?;
/// let device = match device.authenticate_user("123456") {
///     Ok(user) => {
///         perform_user_task(&user);
///         user.device()
///     },
///     Err((device, err)) => {
///         println!("Could not authenticate as user: {:?}", err);
///         device
///     },
/// };
/// perform_other_task(&device);
/// #     Ok(())
/// # }
/// ```
///
/// [`connect`]: fn.connect.html
// TODO: add example for Storage-specific code
#[derive(Debug)]
pub enum DeviceWrapper {
    /// A Nitrokey Storage device.
    Storage(Storage),
    /// A Nitrokey Pro device.
    Pro(Pro),
}

/// A Nitrokey Pro device without user or admin authentication.
///
/// Use the global function [`connect`][] to obtain an instance wrapper or the method
/// [`connect`][`Pro::connect`] to directly obtain an instance.  If you want to execute a command
/// that requires user or admin authentication, use [`authenticate_admin`][] or
/// [`authenticate_user`][].
///
/// # Examples
///
/// Authentication with error handling:
///
/// ```no_run
/// use nitrokey::{Authenticate, User, Pro};
/// # use nitrokey::CommandError;
///
/// fn perform_user_task(device: &User<Pro>) {}
/// fn perform_other_task(device: &Pro) {}
///
/// # fn try_main() -> Result<(), CommandError> {
/// let device = nitrokey::Pro::connect()?;
/// let device = match device.authenticate_user("123456") {
///     Ok(user) => {
///         perform_user_task(&user);
///         user.device()
///     },
///     Err((device, err)) => {
///         println!("Could not authenticate as user: {:?}", err);
///         device
///     },
/// };
/// perform_other_task(&device);
/// #     Ok(())
/// # }
/// ```
///
/// [`authenticate_admin`]: trait.Authenticate.html#method.authenticate_admin
/// [`authenticate_user`]: trait.Authenticate.html#method.authenticate_user
/// [`connect`]: fn.connect.html
/// [`Pro::connect`]: #method.connect
#[derive(Debug)]
pub struct Pro {}

/// A Nitrokey Storage device without user or admin authentication.
///
/// Use the global function [`connect`][] to obtain an instance wrapper or the method
/// [`connect`][`Storage::connect`] to directly obtain an instance.  If you want to execute a
/// command that requires user or admin authentication, use [`authenticate_admin`][] or
/// [`authenticate_user`][].
///
/// # Examples
///
/// Authentication with error handling:
///
/// ```no_run
/// use nitrokey::{Authenticate, User, Storage};
/// # use nitrokey::CommandError;
///
/// fn perform_user_task(device: &User<Storage>) {}
/// fn perform_other_task(device: &Storage) {}
///
/// # fn try_main() -> Result<(), CommandError> {
/// let device = nitrokey::Storage::connect()?;
/// let device = match device.authenticate_user("123456") {
///     Ok(user) => {
///         perform_user_task(&user);
///         user.device()
///     },
///     Err((device, err)) => {
///         println!("Could not authenticate as user: {:?}", err);
///         device
///     },
/// };
/// perform_other_task(&device);
/// #     Ok(())
/// # }
/// ```
///
/// [`authenticate_admin`]: trait.Authenticate.html#method.authenticate_admin
/// [`authenticate_user`]: trait.Authenticate.html#method.authenticate_user
/// [`connect`]: fn.connect.html
/// [`Storage::connect`]: #method.connect
#[derive(Debug)]
pub struct Storage {}

/// A Nitrokey device.
///
/// This trait provides the commands that can be executed without authentication and that are
/// present on all supported Nitrokey devices.
pub trait Device: Authenticate + GetPasswordSafe + GenerateOtp {
    /// Returns the serial number of the Nitrokey device.  The serial number is the string
    /// representation of a hex number.
    ///
    /// # Example
    ///
    /// ```no_run
    /// use nitrokey::Device;
    /// # use nitrokey::CommandError;
    ///
    /// # fn try_main() -> Result<(), CommandError> {
    /// let device = nitrokey::connect()?;
    /// match device.get_serial_number() {
    ///     Ok(number) => println!("serial no: {:?}", number),
    ///     Err(err) => println!("Could not get serial number: {:?}", err),
    /// };
    /// #     Ok(())
    /// # }
    /// ```
    fn get_serial_number(&self) -> Result<String, CommandError> {
        unsafe { result_from_string(nitrokey_sys::NK_device_serial_number()) }
    }

    /// Returns the number of remaining authentication attempts for the user.  The total number of
    /// available attempts is three.
    ///
    /// # Example
    ///
    /// ```no_run
    /// use nitrokey::Device;
    /// # use nitrokey::CommandError;
    ///
    /// # fn try_main() -> Result<(), CommandError> {
    /// let device = nitrokey::connect()?;
    /// let count = device.get_user_retry_count();
    /// println!("{} remaining authentication attempts (user)", count);
    /// #     Ok(())
    /// # }
    /// ```
    fn get_user_retry_count(&self) -> u8 {
        unsafe { nitrokey_sys::NK_get_user_retry_count() }
    }

    /// Returns the number of remaining authentication attempts for the admin.  The total number of
    /// available attempts is three.
    ///
    /// # Example
    ///
    /// ```no_run
    /// use nitrokey::Device;
    /// # use nitrokey::CommandError;
    ///
    /// # fn try_main() -> Result<(), CommandError> {
    /// let device = nitrokey::connect()?;
    /// let count = device.get_admin_retry_count();
    /// println!("{} remaining authentication attempts (admin)", count);
    /// #     Ok(())
    /// # }
    /// ```
    fn get_admin_retry_count(&self) -> u8 {
        unsafe { nitrokey_sys::NK_get_admin_retry_count() }
    }

    /// Returns the major part of the firmware version (should be zero).
    ///
    /// # Example
    ///
    /// ```no_run
    /// use nitrokey::Device;
    /// # use nitrokey::CommandError;
    ///
    /// # fn try_main() -> Result<(), CommandError> {
    /// let device = nitrokey::connect()?;
    /// println!(
    ///     "Firmware version: {}.{}",
    ///     device.get_major_firmware_version(),
    ///     device.get_minor_firmware_version(),
    /// );
    /// #     Ok(())
    /// # }
    /// ```
    fn get_major_firmware_version(&self) -> i32 {
        unsafe { nitrokey_sys::NK_get_major_firmware_version() }
    }

    /// Returns the minor part of the firmware version (for example 8 for version 0.8).
    ///
    /// # Example
    ///
    /// ```no_run
    /// use nitrokey::Device;
    /// # use nitrokey::CommandError;
    ///
    /// # fn try_main() -> Result<(), CommandError> {
    /// let device = nitrokey::connect()?;
    /// println!(
    ///     "Firmware version: {}.{}",
    ///     device.get_major_firmware_version(),
    ///     device.get_minor_firmware_version(),
    /// );
    /// #     Ok(())
    /// # }
    fn get_minor_firmware_version(&self) -> i32 {
        unsafe { nitrokey_sys::NK_get_minor_firmware_version() }
    }

    /// Returns the current configuration of the Nitrokey device.
    ///
    /// # Example
    ///
    /// ```no_run
    /// use nitrokey::Device;
    /// # use nitrokey::CommandError;
    ///
    /// # fn try_main() -> Result<(), CommandError> {
    /// let device = nitrokey::connect()?;
    /// let config = device.get_config()?;
    /// println!("numlock binding:          {:?}", config.numlock);
    /// println!("capslock binding:         {:?}", config.capslock);
    /// println!("scrollock binding:        {:?}", config.scrollock);
    /// println!("require password for OTP: {:?}", config.user_password);
    /// #     Ok(())
    /// # }
    /// ```
    fn get_config(&self) -> Result<Config, CommandError> {
        unsafe {
            let config_ptr = nitrokey_sys::NK_read_config();
            if config_ptr.is_null() {
                return Err(get_last_error());
            }
            let config_array_ptr = config_ptr as *const [u8; 5];
            let raw_config = RawConfig::from(*config_array_ptr);
            libc::free(config_ptr as *mut libc::c_void);
            return Ok(raw_config.into());
        }
    }

    /// Changes the administrator PIN.
    ///
    /// # Errors
    ///
    /// - [`InvalidString`][] if one of the provided passwords contains a null byte
    /// - [`WrongPassword`][] if the current admin password is wrong
    ///
    /// # Example
    ///
    /// ```no_run
    /// use nitrokey::{CommandStatus, Device};
    /// # use nitrokey::CommandError;
    ///
    /// # fn try_main() -> Result<(), CommandError> {
    /// let device = nitrokey::connect()?;
    /// match device.change_admin_pin("12345678", "12345679") {
    ///     CommandStatus::Success => println!("Updated admin PIN."),
    ///     CommandStatus::Error(err) => println!("Failed to update admin PIN: {:?}", err),
    /// };
    /// #     Ok(())
    /// # }
    /// ```
    ///
    /// [`InvalidString`]: enum.CommandError.html#variant.InvalidString
    /// [`WrongPassword`]: enum.CommandError.html#variant.WrongPassword
    fn change_admin_pin(&self, current: &str, new: &str) -> CommandStatus {
        let current_string = CString::new(current);
        let new_string = CString::new(new);
        if current_string.is_err() || new_string.is_err() {
            return CommandStatus::Error(CommandError::InvalidString);
        }
        let current_string = current_string.unwrap();
        let new_string = new_string.unwrap();
        unsafe {
            CommandStatus::from(nitrokey_sys::NK_change_admin_PIN(
                current_string.as_ptr(),
                new_string.as_ptr(),
            ))
        }
    }

    /// Changes the user PIN.
    ///
    /// # Errors
    ///
    /// - [`InvalidString`][] if one of the provided passwords contains a null byte
    /// - [`WrongPassword`][] if the current user password is wrong
    ///
    /// # Example
    ///
    /// ```no_run
    /// use nitrokey::{CommandStatus, Device};
    /// # use nitrokey::CommandError;
    ///
    /// # fn try_main() -> Result<(), CommandError> {
    /// let device = nitrokey::connect()?;
    /// match device.change_user_pin("123456", "123457") {
    ///     CommandStatus::Success => println!("Updated admin PIN."),
    ///     CommandStatus::Error(err) => println!("Failed to update admin PIN: {:?}", err),
    /// };
    /// #     Ok(())
    /// # }
    /// ```
    ///
    /// [`InvalidString`]: enum.CommandError.html#variant.InvalidString
    /// [`WrongPassword`]: enum.CommandError.html#variant.WrongPassword
    fn change_user_pin(&self, current: &str, new: &str) -> CommandStatus {
        let current_string = CString::new(current);
        let new_string = CString::new(new);
        if current_string.is_err() || new_string.is_err() {
            return CommandStatus::Error(CommandError::InvalidString);
        }
        let current_string = current_string.unwrap();
        let new_string = new_string.unwrap();
        unsafe {
            CommandStatus::from(nitrokey_sys::NK_change_user_PIN(
                current_string.as_ptr(),
                new_string.as_ptr(),
            ))
        }
    }
}

/// Connects to a Nitrokey device.  This method can be used to connect to any connected device,
/// both a Nitrokey Pro and a Nitrokey Storage.
///
/// # Example
///
/// ```
/// use nitrokey::DeviceWrapper;
///
/// fn do_something(device: DeviceWrapper) {}
///
/// match nitrokey::connect() {
///     Ok(device) => do_something(device),
///     Err(err) => println!("Could not connect to a Nitrokey: {:?}", err),
/// }
/// ```
pub fn connect() -> Result<DeviceWrapper, CommandError> {
    unsafe {
        match nitrokey_sys::NK_login_auto() {
            1 => match get_connected_device() {
                Some(wrapper) => Ok(wrapper),
                None => Err(CommandError::Unknown),
            },
            _ => Err(CommandError::Unknown),
        }
    }
}

fn get_connected_device() -> Option<DeviceWrapper> {
    // TODO: check connected device
    Some(DeviceWrapper::Pro(Pro {}))
}

fn connect_model(model: Model) -> bool {
    let model = match model {
        Model::Storage => nitrokey_sys::NK_device_model_NK_STORAGE,
        Model::Pro => nitrokey_sys::NK_device_model_NK_PRO,
    };
    unsafe { nitrokey_sys::NK_login_enum(model) == 1 }
}

impl DeviceWrapper {
    fn device(&self) -> &Device {
        match *self {
            DeviceWrapper::Storage(ref storage) => storage,
            DeviceWrapper::Pro(ref pro) => pro,
        }
    }
}

impl GenerateOtp for DeviceWrapper {
    fn get_hotp_slot_name(&self, slot: u8) -> Result<String, CommandError> {
        self.device().get_hotp_slot_name(slot)
    }

    fn get_totp_slot_name(&self, slot: u8) -> Result<String, CommandError> {
        self.device().get_totp_slot_name(slot)
    }

    fn get_hotp_code(&self, slot: u8) -> Result<String, CommandError> {
        self.device().get_hotp_code(slot)
    }

    fn get_totp_code(&self, slot: u8) -> Result<String, CommandError> {
        self.device().get_totp_code(slot)
    }
}

impl Device for DeviceWrapper {}

impl Pro {
    pub fn connect() -> Result<Pro, CommandError> {
        // TODO: maybe Option instead of Result?
        match connect_model(Model::Pro) {
            true => Ok(Pro {}),
            false => Err(CommandError::Unknown),
        }
    }
}

impl Drop for Pro {
    fn drop(&mut self) {
        unsafe {
            nitrokey_sys::NK_logout();
        }
    }
}

impl Device for Pro {}

impl GenerateOtp for Pro {}

impl Storage {
    pub fn connect() -> Result<Storage, CommandError> {
        // TODO: maybe Option instead of Result?
        match connect_model(Model::Storage) {
            true => Ok(Storage {}),
            false => Err(CommandError::Unknown),
        }
    }
}

impl Drop for Storage {
    fn drop(&mut self) {
        unsafe {
            nitrokey_sys::NK_logout();
        }
    }
}

impl Device for Storage {}

impl GenerateOtp for Storage {}