use core::error::Error;

use core::fmt::Debug;

use core::fmt::Display;

/// The Merc error type. This has a blanket [`From`] impl for any type that implements Rust's [`Error`],

/// meaning it can be used as a "catch all" error. Captures a backtrace that can be printed from this object.

pub struct MercError {

    inner: Box<InnerMercError>,

}

impl MercError {

    /// Attempts to downcast the internal error to the given type.

    ///

    /// This is useful when you need to inspect or handle a specific error type

    /// that may have been wrapped inside a `MercError`.

    ///

    /// # Examples

    ///

    /// ```

    /// use merc_utilities::MercError;

    /// use std::io;

    ///

    /// fn handle_error(err: MercError) {

    ///     // Check if the underlying error is an IO error

    ///     if let Some(io_err) = err.downcast_ref::<io::Error>() {

    ///         println!("IO error occurred: {}", io_err.kind());

    ///     } else {

    ///         println!("Some other error occurred");

    ///     }

    /// }

    /// ```

    #[must_use]

}

/// This type exists to make [`MercError`] use a "thin pointer" instead of a

/// "fat pointer", which reduces the size of our Result by a usize. This does

/// introduce an extra indirection, but error handling is a "cold path". We

/// don't need to optimize it to that degree.

struct InnerMercError {

    /// The underlying error

    error: Box<dyn Error + Send + Sync + 'static>,

    /// A backtrace captured at creation

    backtrace: std::backtrace::Backtrace,

}

// NOTE: writing the impl this way gives us From<&str>

impl<E> From<E> for MercError

where

    Box<dyn Error + Send + Sync + 'static>: From<E>,

{

    #[cold]

}

impl MercError {

    /// Appends the captured backtrace on its own line, if one was captured.

    /// Shared by the `Display` and `Debug` impls.

}

impl Display for MercError {

}

impl Debug for MercError {

}