//! Support for using `tor-error` with the `tracing` crate.

use crate::ErrorKind;

#[doc(hidden)]

pub use static_assertions;

#[doc(hidden)]

pub use tracing::{Level, event};

use paste::paste;

impl ErrorKind {

    /// Return true if this [`ErrorKind`] should always be logged as

    /// a warning (or more severe).

}

/// Log a [`Report`](crate::Report) of a provided error at a given level, or a

/// higher level if appropriate.

///

/// (If [`ErrorKind::is_always_a_warning`] returns true for the error's kind, we

/// log it at WARN, unless this event is already at level WARN or ERROR.)

///

/// # Examples

///

/// ```

/// # // this is what implements HasKind in this crate.

/// # fn demo(err: &futures::task::SpawnError) {

/// # let num = 7;

/// use tor_error::event_report;

/// use tracing::Level;

///

/// event_report!(Level::DEBUG, err, "Couldn't chew gum while walking");

///

/// event_report!(Level::TRACE, err, attempt = %num, "Ephemeral error");

/// # }

/// ```

///

/// # Limitations

///

/// This macro does not support the full range of syntaxes supported by

/// [`tracing::event!`].

//

// NOTE: We need this fancy conditional here because tracing::event! insists on

// getting a const expression for its `Level`.  So we can do

// `if cond {debug!(..)} else {warn!(..)}`,

// but we can't do

// `event!(if cond {DEBUG} else {WARN}, ..)`.

#[macro_export]

macro_rules! event_report {

    ($level:expr, $err:expr) => {

        $crate::event_report!($level, $err,)

    };

    ($level:expr, $err:expr, $($arg:tt)*) => {

        {

            use $crate::{tracing as tr, HasKind as _, };

            let err = $err;

            if err.kind().is_always_a_warning() && tr::Level::WARN < $level {

                $crate::event_report!(@raw tr::Level::WARN, err, $($arg)*);

            } else {

                $crate::event_report!(@raw $level, err, $($arg)*);

            }

        }

    };

    (@raw $level:expr, $err:expr) => {

        $crate::event_report!(@raw $level, $err,)

    };

    (@raw $level:expr, $err:expr, $($arg:tt)*) => {

        {

            use $crate::tracing as tr;

            use ::std::ops::Deref as _;

            tr::event!(

                $level,

                // some types like `anyhow::Error` can deref to a `dyn Error`, and we cast as

                // `&dyn Error` so that it is handled as an error type by a tracing field

                // visitor (see `Visit::record_error()` from `tracing-core`)

                error = ((&($err)).deref() as &dyn std::error::Error),

                $($arg)*

            )

        }

    }

}

/// Define a macro `$level_report`

///

/// The title line for the doc comment will be

/// ``$title_1 `LEVEL` $title_2``

///

/// A standard body, containing a set of examples, will be provided.

///

/// You must pass a dollar sign for `D`, because there is no dollar escaping mechanism

/// for macro_rules macros in stable Rust (!)

macro_rules! define_report_macros { {

    # $title_1:tt

    LEVEL

    # $title_2:tt

    $D:tt

    $( [$($flag:tt)*] $level:ident )*

} => { $( paste!{

    # $title_1

    #[doc = concat!("`", stringify!( [< $level:upper >] ), "`")]

    # $title_2

    ///

    /// # Examples:

    ///

    /// ```

    /// # fn demo(err: &futures::task::SpawnError) {

    /// # let msg = ();

    #[doc = concat!("use tor_error::", stringify!($level), "_report;")]

    #[doc = concat!(stringify!($level), "_report!",

                    r#"(err, "Cheese exhausted (ephemeral)");"#)]

    #[doc = concat!(stringify!($level), "_report!",

                    r#"(err, "Unable to parse message {:?}", msg);"#)]

    /// # }

    /// ```

    #[macro_export]

    macro_rules! [< $level _report >] {

        ( $D err:expr ) => {

            // would be nice to do a `$D crate::[< $level _report >]!($D err,)` here,

            // but apparently this isn't allowed:

            // https://github.com/rust-lang/rust/pull/52234

            $D crate::event_report!($($flag)*

                                    $D crate::tracing::Level::[< $level:upper >],

                                    $D err)

        };

        ( $D err:expr, $D ($D rest:tt)* ) => {

            $D crate::event_report!($($flag)*

                                    $D crate::tracing::Level::[< $level:upper >],

                                    $D err, $D ($D rest)*)

        }

    }

} )* } }

define_report_macros! {

    /// Log a report for `err` at level

    LEVEL

    /// (or higher if it is a bug).

    $ [] trace

      [] debug

      [] info

}

define_report_macros! {

    /// Log a report for `err` at level

    LEVEL

    ///

    $ [@raw] warn

      [@raw] error

}

#[cfg(test)]

mod test {

    // @@ begin test lint list maintained by maint/add_warning @@

    #![allow(clippy::bool_assert_comparison)]

    #![allow(clippy::clone_on_copy)]

    #![allow(clippy::dbg_macro)]

    #![allow(clippy::mixed_attributes_style)]

    #![allow(clippy::print_stderr)]

    #![allow(clippy::print_stdout)]

    #![allow(clippy::single_char_pattern)]

    #![allow(clippy::unwrap_used)]

    #![allow(clippy::unchecked_duration_subtraction)]

    #![allow(clippy::useless_vec)]

    #![allow(clippy::needless_pass_by_value)]

    //! <!-- @@ end test lint list maintained by maint/add_warning @@ -->

    use crate::internal;

    use crate::report::ErrorReport;

    use thiserror::Error;

    use tracing_test::traced_test;

    #[derive(Error, Debug)]

    #[error("my error")]

    struct MyError;

    #[test]

    #[traced_test]

    // i really don't think that this test is too complicated

    #[allow(clippy::cognitive_complexity)]

    fn warn_report() {

        let me = MyError;

        let _ = me.report();

        warn_report!(me, "reporting unwrapped");

        let ae = anyhow::Error::from(me).context("context");

        let _ = ae.report();

        warn_report!(ae, "reporting anyhow");

        let ie = internal!("Foo was not initialized");

        let _ = ie.report();

        warn_report!(ie);

    }

}