//! This module contains all the traits and types for creating a cross-platform API to query
//! different readouts from various operating systems. For each operating system, there must be an implementation of these traits.

/// This enum contains possible error types when doing sensor & variable readouts.
#[derive(Debug, Clone)]
pub enum ReadoutError {
    /// A specific metric might not be available on all systems (e. g. battery percentage on a
    /// desktop). \
    /// If you encounter this error, it means that the requested value is not available.
    MetricNotAvailable,

    /// A readout for a metric might be available, but fails due to missing dependencies or other
    /// unsatisfied requirements.
    Other(String),

    /// Getting a readout on a specific operating system might not make sense or causes some other
    /// kind of warning. This is not necessarily an error.
    Warning(String),
}

impl ToString for ReadoutError {
    fn to_string(&self) -> String {
        match self {
            ReadoutError::MetricNotAvailable => {
                String::from("Metric is not available on this system.")
            }
            ReadoutError::Other(s) => s.clone(),
            ReadoutError::Warning(s) => s.clone(),
        }
    }
}

impl From<&ReadoutError> for ReadoutError {
    fn from(r: &ReadoutError) -> Self {
        r.to_owned()
    }
}

lazy_static! {
    static ref STANDARD_NO_IMPL: ReadoutError = ReadoutError::Warning(String::from(
        "This metric is not available on this platform or is not yet implemented by Macchina."
    ));
}

/**
This trait provides the necessary functions for querying battery statistics from the host
computer. A desktop computer might not be able to provide values such as `percentage` and
`status`, which means a `ReadoutError` can be returned.

# Example

```
use libmacchina::traits::BatteryReadout;
use libmacchina::traits::ReadoutError;
use libmacchina::traits::BatteryState;

//You can add fields to this struct which will then need to be initialized in the
//BatteryReadout::new() function.
pub struct MacOSBatteryReadout;

impl BatteryReadout for MacOSBatteryReadout {
    fn new() -> Self {
        MacOSBatteryReadout {}
    }

    fn percentage(&self) -> Result<u8, ReadoutError> {
        //get the battery percentage somehow...
        Ok(100u8) //always fully charged
    }

    fn status(&self) -> Result<BatteryState, ReadoutError> {
        //check if battery is being charged...
        Ok(BatteryState::Charging) //always charging.
    }
}
```
*/
pub trait BatteryReadout {
    /// Creates a new instance of the structure which implements this trait.
    fn new() -> Self;

    /// This function is used for querying the current battery percentage. The expected value is
    /// a u8 in the range of `0` to `100`.
    fn percentage(&self) -> Result<u8, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function is used for querying the current battery charging state. If the battery is
    /// currently being charged, we expect a return value of `BatteryState::Charging`, otherwise
    /// `BatteryState::Discharging`.
    fn status(&self) -> Result<BatteryState, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }
}

/**
This trait is used for implementing common functions for reading kernel properties, such as
kernel name and version.

# Example

```
use libmacchina::traits::KernelReadout;
use libmacchina::traits::ReadoutError;

pub struct MacOSKernelReadout;

impl KernelReadout for MacOSKernelReadout {
    fn new() -> Self {
        MacOSKernelReadout {}
    }

    fn os_release(&self) -> Result<String, ReadoutError> {
        // Get kernel version
        Ok(String::from("20.0.1"))
    }

    fn os_type(&self) -> Result<String, ReadoutError> {
        // Get kernel name
        Ok(String::from("Darwin"))
    }
}
```
*/
pub trait KernelReadout {
    /// Creates a new instance of the structure which implements this trait.
    fn new() -> Self;

    /// This function should return the version of the kernel (e. g. `20.3.0` on macOS for Darwin).
    fn os_release(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the kernel name as a string (e. g. `Darwin` on macOS).
    fn os_type(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function is used for getting the kernel name and version in a pretty format.
    fn pretty_kernel(&self) -> Result<String, ReadoutError> {
        let os_type = self.os_type().unwrap_or_default();
        let os_release = self.os_release().unwrap_or_default();

        if !(os_type.is_empty() || os_release.is_empty()) {
            return Ok(format!("{} {}", os_type, os_release));
        }

        Err(ReadoutError::MetricNotAvailable)
    }
}

/**
This trait provides common functions for _querying the current memory state_ of the host
device, most notably `free` and `used`.

# Example

```
use libmacchina::traits::MemoryReadout;
use libmacchina::traits::ReadoutError;

pub struct MacOSMemoryReadout;

impl MemoryReadout for MacOSMemoryReadout {
    fn new() -> Self {
        MacOSMemoryReadout {}
    }

    fn total(&self) -> Result<u64, ReadoutError> {
        // Get the total physical memory for the machine
        Ok(512 * 1024) // Return 512mb in kilobytes.
    }

    fn used(&self) -> Result<u64, ReadoutError> {
        // Get the currently used memory.
        Ok(256 * 1024) // Return 256mb in kilobytes.
    }
}

```
*/
pub trait MemoryReadout {
    /// Creates a new instance of the structure which implements this trait.
    fn new() -> Self;

    /// This function should return the total available memory in kilobytes.
    fn total(&self) -> Result<u64, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the free available memory in kilobytes.
    fn free(&self) -> Result<u64, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the current memory value for buffers in kilobytes.
    fn buffers(&self) -> Result<u64, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the amount of cached content in memory in kilobytes.
    fn cached(&self) -> Result<u64, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the amount of reclaimable memory in kilobytes.
    fn reclaimable(&self) -> Result<u64, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the amount of currently used memory in kilobytes.
    fn used(&self) -> Result<u64, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }
}

/**
This trait provides the interface for implementing functionality used for _counting packages_ on
the host system. Almost all modern operating systems use some kind of package manager.

# Example

```
use libmacchina::traits::{PackageReadout, PackageManager};
use libmacchina::traits::ReadoutError;

pub struct MacOSPackageReadout;

impl PackageReadout for MacOSPackageReadout {
    fn new() -> Self {
        MacOSPackageReadout {}
    }

    fn count_pkgs(&self) -> Vec<(PackageManager, usize)> {
        // Check if homebrew 🍻 is installed and count installed packages...
        vec![(PackageManager::Homebrew, 120)]
    }
}
```
*/
pub trait PackageReadout {
    /// Creates a new instance of the structure which implements this trait.
    fn new() -> Self;

    /// This function should return the number of installed packages.
    fn count_pkgs(&self) -> Vec<(PackageManager, usize)> {
        Vec::new()
    }
}

/**
This trait provides the interface for implementing functionality used for getting _product information_
about the hosts operating system.

# Example

```
use libmacchina::traits::ProductReadout;
use libmacchina::traits::ReadoutError;

pub struct MacOSProductReadout;

impl ProductReadout for MacOSProductReadout {
    fn new() -> Self {
        MacOSProductReadout {}
    }

    fn vendor(&self) -> Result<String, ReadoutError> {
        Ok(String::from("Apple"))
    }

    fn family(&self) -> Result<String, ReadoutError> {
        Ok(String::from("Unix, Macintosh"))
    }

    fn name(&self) -> Result<String, ReadoutError> {
        // Get name of os release...
        Ok(String::from("Big Sur"))
    }

    fn product(&self) -> Result<String, ReadoutError> {
        Ok(String::from("macOS"))
    }
}
```
*/
pub trait ProductReadout {
    /// Creates a new instance of the structure which implements this trait.
    fn new() -> Self;

    /// This function should return the version of the host's machine.
    ///
    /// _e.g._ `Lenovo IdeaPad S540-15IWL GTX`
    ///
    /// This is set by the machine's manufacturer.
    fn version(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the vendor name of the host's machine.
    ///
    /// _e.g._ `Lenovo`
    ///
    /// This is set by the machine's manufacturer.
    fn vendor(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the family name of the host's machine.
    ///
    /// _e.g._ `IdeaPad S540-15IWL GTX`
    ///
    /// This is set by the machine's manufacturer.
    fn family(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the name of the host's machine.
    ///
    /// _e.g._ `81SW`
    ///
    /// This is set by the machine's manufacturer.
    fn name(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the product name of the hosts machine.
    ///
    /// _e.g._ `IdeaPad S540-15IWL GTX`
    ///
    /// This is set by the machine's manufacturer.
    fn product(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }
}

/**
This trait provides the interface for implementing functionality used for querying general
information about the running operating system and current user.

# Example

```
use libmacchina::traits::GeneralReadout;
use libmacchina::traits::ReadoutError;

pub struct MacOSGeneralReadout;

impl GeneralReadout for MacOSGeneralReadout {

    fn new() -> Self {
        MacOSGeneralReadout {}
    }

    fn username(&self) -> Result<String, ReadoutError> {
        //let username = NSUserName();
        Ok(String::from("johndoe"))
    }

    // Implement other trait functions...
}

```
*/
pub trait GeneralReadout {
    /// Creates a new instance of the structure which implements this trait.
    fn new() -> Self;

    /// This function should return the username of the currently logged on user.
    ///
    /// _e.g._ `johndoe`
    fn username(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the hostname of the host's computer.
    ///
    /// _e.g._ `supercomputer`
    fn hostname(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the name of the distribution of the operating system.
    ///
    /// _e.g._ `Arch Linux`
    fn distribution(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the user's local ip address
    ///
    /// _e.g._ `192.168.1.11`
    fn local_ip(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the name of the used desktop environment.
    ///
    /// _e.g._ `Plasma`
    fn desktop_environment(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the name of the used window manager.
    ///
    /// _e.g._ `KWin`
    fn window_manager(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the name of the used terminal emulator.
    ///
    /// _e.g._ `kitty`
    fn terminal(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /**
    This function should return the currently running shell depending on the `_shorthand` value.

    - If `_shorthand` is `ShellFormat::Relative` the basename of the shell will be returned.

    _e.g._ bash, zsh, etc.

    - If `_shorthand` is `ShellFormat::Absolute` the absolute path of the shell will be returned.

    _e.g._ /bin/bash, /bin/zsh, etc.
    */
    fn shell(&self, _shorthand: ShellFormat) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the model name of the CPU \
    ///
    /// _e.g._ `Intel(R) Core(TM) i5-8265U CPU @ 1.60GHz`
    fn cpu_model_name(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the average CPU usage over the last minute.
    fn cpu_usage(&self) -> Result<usize, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the number of physical cores of the host's processor.
    fn cpu_physical_cores(&self) -> Result<usize, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the number of logical cores of the host's processor.
    fn cpu_cores(&self) -> Result<usize, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the uptime of the OS in seconds.
    fn uptime(&self) -> Result<usize, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the name of the physical machine
    ///
    /// _e.g._ `MacBookPro11,5`
    fn machine(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }

    /// This function should return the name of the OS in a pretty format
    ///
    /// _e.g._ `macOS 11.2.2 Big Sur`
    fn os_name(&self) -> Result<String, ReadoutError> {
        Err(STANDARD_NO_IMPL.clone())
    }
}

/// Holds the possible variants for battery status.
pub enum BatteryState {
    Charging,
    Discharging,
}

impl From<BatteryState> for &'static str {
    fn from(state: BatteryState) -> &'static str {
        match state {
            BatteryState::Charging => "Charging",
            BatteryState::Discharging => "Discharging",
        }
    }
}

/// The currently running shell is a program, whose path
/// can be _relative_, or _absolute_.
#[derive(Debug)]
pub enum ShellFormat {
    Relative,
    Absolute,
}

/// The supported package managers whose packages can be extracted.
pub enum PackageManager {
    Homebrew,
    MacPorts,
    Pacman,
    Portage,
    Dpkg,
    Opkg,
    Xbps,
    Pkgsrc,
    Apk,
    Eopkg,
    Rpm,
    Cargo,
    Flatpak,
    Snap,
    Android,
}

impl ToString for PackageManager {
    fn to_string(&self) -> String {
        String::from(match self {
            PackageManager::Homebrew => "Homebrew",
            PackageManager::MacPorts => "MacPorts",
            PackageManager::Pacman => "pacman",
            PackageManager::Portage => "portage",
            PackageManager::Dpkg => "dpkg",
            PackageManager::Opkg => "opkg",
            PackageManager::Xbps => "xbps",
            PackageManager::Pkgsrc => "pkgsrc",
            PackageManager::Apk => "apk",
            PackageManager::Eopkg => "eopkg",
            PackageManager::Rpm => "rpm",
            PackageManager::Cargo => "cargo",
            PackageManager::Flatpak => "flatpak",
            PackageManager::Snap => "snap",
            PackageManager::Android => "Android",
        })
    }
}