//
// Copyright (C) 2018 Kubos Corporation
//
// Licensed under the Apache License, Version 2.0 (the "License")
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//

use std::mem;

mod ffi;

/// Structure returned by supervisor_version
#[derive(Debug)]
pub struct SupervisorVersion {
    pub dummy: u8,
    pub spi_command_status: u8,
    pub index_of_subsystem: u8,
    pub major_version: u8,
    pub minor_version: u8,
    pub patch_version: u8,
    pub git_head_version: u32,
    pub serial_number: u16,
    pub compile_information: [i8; ffi::LENGTH_COMPILE_INFORMATION],
    pub clock_speed: u8,
    pub code_type: i8,
    pub crc: u8,
}

/// Structure for individual enable statuses
/// Used in SupervisorHousekeeping
#[derive(Clone, Copy, Debug)]
pub struct SupervisorEnableStatus {
    pub power_obc: u8,
    pub power_rtc: u8,
    pub supervisor_mode: u8,
    pub busy_rtc: u8,
    pub power_off_rtc: u8,
}

/// Structure returned by supervisor_housekeeping
#[derive(Debug)]
pub struct SupervisorHousekeeping {
    pub dummy: u8,
    pub spi_command_status: u8,
    pub enable_status: SupervisorEnableStatus,
    pub supervisor_uptime: u32,
    pub iobc_uptime: u32,
    pub iobc_reset_count: u32,
    pub adc_data: [u16; ffi::SUPERVISOR_NUMBER_OF_ADC_CHANNELS],
    pub adc_update_flag: u8,
    pub crc8: u8,
}

/// Supervisor emergency reset interface
pub fn supervisor_emergency_reset() -> Result<(), String> {
    if unsafe { ffi::supervisor_emergency_reset() } {
        Ok(())
    } else {
        Err(String::from("Problem with supervisor emergency reset"))
    }
}

/// Supervisor reset interface
pub fn supervisor_reset() -> Result<(), String> {
    if unsafe { ffi::supervisor_reset() } {
        Ok(())
    } else {
        Err(String::from("Problem with supervisor reset"))
    }
}

/// Supervisor powercycle interface
pub fn supervisor_powercycle() -> Result<(), String> {
    if unsafe { ffi::supervisor_powercycle() } {
        Ok(())
    } else {
        Err(String::from("Problem with supervisor powercycle"))
    }
}

/// Converts raw bytes from iOBC into SupervisorVersion
fn convert_raw_version(raw: &ffi::supervisor_version) -> SupervisorVersion {
    SupervisorVersion {
        dummy: raw.0[0] as u8,
        spi_command_status: raw.0[1] as u8,
        index_of_subsystem: raw.0[2] as u8,
        major_version: raw.0[3] as u8,
        minor_version: raw.0[4] as u8,
        patch_version: raw.0[5] as u8,
        git_head_version: {
            u32::from(raw.0[6])
                | u32::from(raw.0[7]) << 8
                | u32::from(raw.0[8]) << 16
                | u32::from(raw.0[9]) << 24
        },
        serial_number: { u16::from(raw.0[10]) | u16::from(raw.0[11]) << 8 },
        compile_information: {
            let mut a = [0; ffi::LENGTH_COMPILE_INFORMATION];
            for (i, element) in a.iter_mut().enumerate() {
                // 12 is the offset to locate compile_information
                // in the version data
                *element = raw.0[i + 12] as i8;
            }
            a
        },
        clock_speed: raw.0[31] as u8,
        code_type: raw.0[32] as i8,
        crc: raw.0[33] as u8,
    }
}

/// Interface for retrieving iOBC supervisor version data
pub fn supervisor_version() -> Result<SupervisorVersion, String> {
    let mut version: ffi::supervisor_version =
        unsafe { mem::MaybeUninit::<ffi::supervisor_version>::uninit().assume_init() };
    let version_result = unsafe { ffi::supervisor_get_version(&mut version) };
    if !version_result {
        Err(String::from("Problem retrieving supervisor version"))
    } else {
        Ok(convert_raw_version(&version))
    }
}

/// Converts raw bytes from iOBC into SupervisorHousekeeping
fn convert_raw_housekeeping(raw: &ffi::supervisor_housekeeping) -> SupervisorHousekeeping {
    SupervisorHousekeeping {
        dummy: raw.0[0] as u8,
        spi_command_status: raw.0[1] as u8,
        enable_status: SupervisorEnableStatus {
            // We bitmask rather than split the int
            // across bitfields
            power_obc: (raw.0[2] as u8) & 0x1,
            power_rtc: ((raw.0[2] as u8) & 0x2) >> 1,
            supervisor_mode: ((raw.0[2] as u8) & 0x4) >> 2,
            busy_rtc: ((raw.0[2] as u8) & 0x20) >> 5,
            power_off_rtc: ((raw.0[2] as u8) & 0x40) >> 6,
        },
        supervisor_uptime: {
            u32::from(raw.0[3])
                | u32::from(raw.0[4]) << 8
                | u32::from(raw.0[5]) << 16
                | u32::from(raw.0[6]) << 24
        },
        iobc_uptime: {
            u32::from(raw.0[7])
                | u32::from(raw.0[8]) << 8
                | u32::from(raw.0[9]) << 16
                | u32::from(raw.0[10]) << 24
        },
        iobc_reset_count: {
            u32::from(raw.0[11])
                | u32::from(raw.0[12]) << 8
                | u32::from(raw.0[13]) << 16
                | u32::from(raw.0[14]) << 24
        },
        adc_data: {
            // combining bytes into 16-bit uints
            let mut a = [0; ffi::SUPERVISOR_NUMBER_OF_ADC_CHANNELS];
            for (i, element) in a.iter_mut().enumerate() {
                // 15 is the offset to locate the adc data
                // in the housekeeping data
                *element = u16::from(raw.0[15 + 2 * i]) | u16::from(raw.0[15 + 2 * i + 1]) << 8;
            }
            a
        },
        adc_update_flag: raw.0[35] as u8,
        crc8: raw.0[36] as u8,
    }
}

/// Interface for fetching iOBC supervisor housekeeping data
pub fn supervisor_housekeeping() -> Result<SupervisorHousekeeping, String> {
    let mut raw: ffi::supervisor_housekeeping =
        unsafe { mem::MaybeUninit::<ffi::supervisor_housekeeping>::uninit().assume_init() };
    let result = unsafe { ffi::supervisor_get_housekeeping(&mut raw) };

    if !result {
        Err(String::from("Problem retrieving supervisor housekeeping"))
    } else {
        Ok(convert_raw_housekeeping(&raw))
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    /// Accuracy testing conversion of raw bytes into non-C
    /// SupervisorVersion structure
    #[test]
    fn test_convert_version() {
        let raw: ffi::supervisor_version = ffi::supervisor_version([
            0, // dummy (u8)
            1, // spi_command_status (u8)
            2, // index_of_subsystem (u8)
            3, // major_version (u8)
            4, // minor version (u8)
            5, // patch version (u8)
            6, 7, 8, 9, // git_head_version (u32)
            10, 11, // serial_number (u16)
            // compile_information (i8 * 19)
            12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30,
            31, // clock_speed (u8)
            32, // code_type (i8)
            33, // crc8 (u8)
        ]);

        let version = convert_raw_version(&raw);

        assert_eq!(version.dummy, 0);
        assert_eq!(version.spi_command_status, 1);
        assert_eq!(version.major_version, 3);
        assert_eq!(version.minor_version, 4);
        assert_eq!(version.patch_version, 5);
        assert_eq!(version.git_head_version, 151_521_030);
        assert_eq!(version.serial_number, 2826);
        for i in 12..31 {
            assert_eq!(version.compile_information[i - 12], i as i8);
        }
        assert_eq!(version.clock_speed, 31);
        assert_eq!(version.code_type, 32);
        assert_eq!(version.crc, 33);
    }

    /// Accuracy testing conversion of raw bytes into non-C
    /// SupervisorHousekeeping structure
    #[test]
    fn test_convert_housekeeping() {
        let raw: ffi::supervisor_housekeeping = ffi::supervisor_housekeeping([
            0,  // dummy (u8)
            1,  // spi_command_status (u8)
            34, // enable_status (u8) is a bitfield in the C structure
            // power_obc : 1
            // power_rtc : 1
            // supervisor_mode : 1
            // padding : 2
            // busy_rtc : 1
            // power_off_rtc : 1
            // padding: 1
            // Using 34 gives us -
            // 0 0 1 0 0 0 1 0
            // which results in alternating 1/0 field values
            3, 2, 1, 0, // super_uptime (u32)
            4, 3, 2, 1, // iobc_uptime (u32)
            5, 4, 3, 2, // iobc_reset_count (u32)
            // adc_data (u16 * 10)
            0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19,
            12, // adc_update_flag (u8)
            13, // crc8
        ]);

        let housekeeping = convert_raw_housekeeping(&raw);

        assert_eq!(housekeeping.dummy, 0);
        assert_eq!(housekeeping.spi_command_status, 1);
        assert_eq!(housekeeping.enable_status.power_obc, 0);
        assert_eq!(housekeeping.enable_status.power_rtc, 1);
        assert_eq!(housekeeping.enable_status.supervisor_mode, 0);
        assert_eq!(housekeeping.enable_status.busy_rtc, 1);
        assert_eq!(housekeeping.enable_status.power_off_rtc, 0);
        assert_eq!(housekeeping.supervisor_uptime, 66051);
        assert_eq!(housekeeping.iobc_uptime, 16_909_060);
        assert_eq!(housekeeping.iobc_reset_count, 33_752_069);
        assert_eq!(housekeeping.adc_data[0], 256);
        assert_eq!(housekeeping.adc_data[1], 770);
        assert_eq!(housekeeping.adc_data[2], 1284);
        assert_eq!(housekeeping.adc_data[3], 1798);
        assert_eq!(housekeeping.adc_data[4], 2312);
        assert_eq!(housekeeping.adc_data[5], 2826);
        assert_eq!(housekeeping.adc_data[6], 3340);
        assert_eq!(housekeeping.adc_data[7], 3854);
        assert_eq!(housekeeping.adc_data[8], 4368);
        assert_eq!(housekeeping.adc_data[9], 4882);
        assert_eq!(housekeeping.adc_update_flag, 12);
        assert_eq!(housekeeping.crc8, 13);
    }
}