//! Platform abstraction trait for OTA updates

use core::fmt::Write;
use core::str::FromStr;

use super::encoding::FileContext;
use super::state::ImageStateReason;

#[derive(Clone, Copy)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
pub enum ImageState<E: Copy> {
    Unknown,
    Aborted(ImageStateReason<E>),
    Rejected(ImageStateReason<E>),
    Accepted,
    Testing(ImageStateReason<E>),
}

#[derive(Debug, Clone, Copy)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
pub enum OtaPalError<E: Copy> {
    SignatureCheckFailed,
    FileWriteFailed,
    FileTooLarge,
    FileCloseFailed,
    BadFileHandle,
    Unsupported,
    BadImageState,
    CommitFailed,
    VersionCheck,
    Custom(E),
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
pub enum PalImageState {
    /// the new firmware image is in the self test phase
    PendingCommit,
    /// the new firmware image is already committed
    Valid,
    /// the new firmware image is invalid or non-existent
    Invalid,
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
pub enum OtaEvent {
    /// OTA update is authenticated and ready to activate.
    Activate,
    /// OTA update failed. Unable to use this update.
    Fail,
    /// OTA job is now ready for optional user self tests.
    StartTest,

    SelfTestFailed,

    UpdateComplete,
}

#[derive(Debug, Clone, Eq)]
pub struct Version {
    major: u8,
    minor: u8,
    patch: u8,
}

#[cfg(feature = "defmt")]
impl defmt::Format for Version {
    fn format(&self, fmt: defmt::Formatter) {
        defmt::write!(fmt, "{=u8}.{=u8}.{=u8}", self.major, self.minor, self.patch)
    }
}

impl Default for Version {
    fn default() -> Self {
        Self::new(0, 0, 0)
    }
}

impl FromStr for Version {
    type Err = ();

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let mut iter = s.split('.');
        Ok(Self {
            major: iter.next().and_then(|v| v.parse().ok()).ok_or(())?,
            minor: iter.next().and_then(|v| v.parse().ok()).ok_or(())?,
            patch: iter.next().and_then(|v| v.parse().ok()).ok_or(())?,
        })
    }
}

impl Version {
    pub fn new(major: u8, minor: u8, patch: u8) -> Self {
        Self {
            major,
            minor,
            patch,
        }
    }

    pub fn to_string<const L: usize>(&self) -> heapless::String<L> {
        let mut s = heapless::String::new();
        s.write_fmt(format_args!("{}.{}.{}", self.major, self.minor, self.patch))
            .unwrap();
        s
    }
}

impl core::cmp::PartialEq for Version {
    #[inline]
    fn eq(&self, other: &Self) -> bool {
        self.major == other.major && self.minor == other.minor && self.patch == other.patch
    }
}

impl core::cmp::PartialOrd for Version {
    fn partial_cmp(&self, other: &Self) -> Option<core::cmp::Ordering> {
        Some(self.cmp(other))
    }
}

impl core::cmp::Ord for Version {
    fn cmp(&self, other: &Self) -> core::cmp::Ordering {
        match self.major.cmp(&other.major) {
            core::cmp::Ordering::Equal => {}
            r => return r,
        }

        match self.minor.cmp(&other.minor) {
            core::cmp::Ordering::Equal => {}
            r => return r,
        }

        match self.patch.cmp(&other.patch) {
            core::cmp::Ordering::Equal => {}
            r => return r,
        }

        core::cmp::Ordering::Equal
    }
}
/// Platform abstraction layer for OTA jobs
pub trait OtaPal {
    type Error: Copy;

    /// OTA abort.
    ///
    /// The user may register a callback function when initializing the OTA
    /// Agent. This callback is used to override the behavior of how a job is
    /// aborted.
    ///
    /// - `file`: [`FileContext`] File description of the job being aborted
    fn abort(&mut self, file: &FileContext) -> Result<(), OtaPalError<Self::Error>>;

    /// Activate the newest MCU image received via OTA.
    ///
    /// This function shall do whatever is necessary to activate the newest MCU
    /// firmware received via OTA. It is typically just a reset of the device.
    ///
    /// **note** This function SHOULD not return. If it does, the platform
    /// doesn't support an automatic reset or an error occurred.
    ///
    /// **return**: The OTA PAL layer error code combined with the MCU specific
    /// error code.
    fn activate_new_image(&mut self) -> Result<(), OtaPalError<Self::Error>> {
        self.reset_device()
    }

    /// OTA create file to store received data.
    ///
    /// The user may register a callback function when initializing the OTA
    /// Agent. This callback is used to override the behavior of how a new file
    /// is created.
    ///
    /// - `file`: [`FileContext`] File description of the job being aborted
    fn create_file_for_rx(&mut self, file: &FileContext) -> Result<(), OtaPalError<Self::Error>>;

    /// Get the state of the OTA update image.
    ///
    /// We read this at OTA_Init time and when the latest OTA job reports itself
    /// in self test. If the update image is in the "pending commit" state, we
    /// start a self test timer to assure that we can successfully connect to
    /// the OTA services and accept the OTA update image within a reasonable
    /// amount of time (user configurable). If we don't satisfy that
    /// requirement, we assume there is something wrong with the firmware and
    /// automatically reset the device, causing it to roll back to the
    /// previously known working code.
    ///
    /// If the update image state is not in "pending commit," the self test
    /// timer is not started.
    ///
    /// **return** An [`PalImageState`].
    fn get_platform_image_state(&mut self) -> Result<PalImageState, OtaPalError<Self::Error>>;

    /// Attempt to set the state of the OTA update image.
    ///
    /// Do whatever is required by the platform to Accept/Reject the OTA update
    /// image (or bundle). Refer to the PAL implementation to determine what
    /// happens on your platform.
    ///
    /// - `state`: [`ImageState`] The desired state of the OTA update image.
    ///
    /// **return** The [`OtaPalError`] error code combined with the MCU specific
    /// error code.
    fn set_platform_image_state(
        &mut self,
        image_state: ImageState<Self::Error>,
    ) -> Result<(), OtaPalError<Self::Error>>;

    /// Reset the device.
    ///
    /// This function shall reset the MCU and cause a reboot of the system.
    ///
    /// **note** This function SHOULD not return. If it does, the platform
    /// doesn't support an automatic reset or an error occurred.
    ///
    /// **return** The OTA PAL layer error code combined with the MCU specific
    /// error code.
    fn reset_device(&mut self) -> Result<(), OtaPalError<Self::Error>>;

    /// Authenticate and close the underlying receive file in the specified OTA
    /// context.
    ///
    /// If the signature verification fails, file close should still be
    /// attempted.
    ///
    /// - `file`: [`FileContext`] File description of the job being aborted
    ///
    /// **return** The OTA PAL layer error code combined with the MCU specific
    /// error code.
    fn close_file(&mut self, file: &FileContext) -> Result<(), OtaPalError<Self::Error>>;

    /// Write a block of data to the specified file at the given offset.
    ///
    /// - `file`: [`FileContext`] File description of the job being aborted.
    /// - `block_offset`: Byte offset to write to from the beginning of the
    ///   file.
    /// - `block_payload`: Byte array of data to write.
    ///
    /// **return** The number of bytes written on a success, or a negative error
    /// code from the platform abstraction layer.
    fn write_block(
        &mut self,
        file: &FileContext,
        block_offset: usize,
        block_payload: &[u8],
    ) -> Result<usize, OtaPalError<Self::Error>>;

    /// OTA update complete.
    ///
    /// The user may register a callback function when initializing the OTA
    /// Agent. This callback is used to notify the main application when the OTA
    /// update job is complete. Typically, it is used to reset the device after
    /// a successful update by calling `OtaPal::activate_new_image()` and may
    /// also be used to kick off user specified self tests during the Self Test
    /// phase. If the user does not supply a custom callback function, a default
    /// callback handler is used that automatically calls
    /// `OtaPal::activate_new_image()` after a successful update.
    ///
    /// **note**:
    ///
    /// The callback function is called with one of the following arguments:
    ///
    /// - `OtaEvent::Activate`      OTA update is authenticated and ready to
    ///   activate.
    /// - `OtaEvent::Fail`          OTA update failed. Unable to use this
    ///   update.
    /// - `OtaEvent::StartTest`     OTA job is now ready for optional user self
    ///   tests.
    ///
    /// When `OtaEvent::Activate` is received, the job status details have been
    /// updated with the state as ready for Self Test. After reboot, the new
    /// firmware will (normally) be notified that it is in the Self Test phase
    /// via the callback and the application may then optionally run its own
    /// tests before committing the new image.
    ///
    /// If the callback function is called with a result of `OtaEvent::Fail`,
    /// the OTA update job has failed in some way and should be rejected.
    ///
    /// - `event` [`OtaEvent`] An OTA update event from the `OtaEvent` enum.
    fn complete_callback(&mut self, event: OtaEvent) -> Result<(), OtaPalError<Self::Error>> {
        match event {
            OtaEvent::Activate => self.activate_new_image(),
            OtaEvent::Fail | OtaEvent::UpdateComplete => {
                // Nothing special to do. The OTA agent handles it
                Ok(())
            }
            OtaEvent::StartTest => {
                // Accept the image since it was a good transfer
                // and networking and services are all working.
                self.set_platform_image_state(ImageState::Accepted)?;
                Ok(())
            }
            OtaEvent::SelfTestFailed => {
                // Requires manual activation of previous image as self-test for
                // new image downloaded failed.*/
                error!("Self-test failed, shutting down OTA Agent.");

                // Shutdown OTA Agent, if it is required that the unsubscribe operations are not
                // performed while shutting down please set the second parameter to 0 instead of 1.
                Ok(())
            }
        }
    }

    ///
    fn get_active_firmware_version(&self) -> Result<Version, OtaPalError<Self::Error>>;
}