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

use crate::ErrorKind;

use std::sync::atomic::{AtomicU8, Ordering};

#[doc(hidden)]

pub use static_assertions;

#[doc(hidden)]

pub use tracing::{Level, event};

use paste::paste;

/// Runtime policy for handling protocol warnings.

#[derive(Copy, Clone, Debug, Eq, PartialEq)]

#[repr(u8)]

#[non_exhaustive]

pub enum ProtocolWarningMode {

    /// Do not promote protocol-violation reports based on runtime policy.

    Off = 0,

    /// Promote protocol-violation reports to warning level.

    Warn = 1,

}

impl ProtocolWarningMode {

    /// Convert an integer (raw bytes) to a protocol-warning mode (enum).

        }

}

/// Global runtime state for protocol-warning behavior.

static PROTOCOL_WARNING_MODE: AtomicU8 = AtomicU8::new(ProtocolWarningMode::Off as u8);

/// Set runtime policy for protocol-warning log handling.

/// Return current runtime policy for protocol-warning log handling.

/// Return true if the given [`ErrorKind`] is eligible for promotion to `WARN` by

/// [`event_report!`] and related macros.

///

/// This is true if [`ErrorKind::is_always_a_warning`] returns true, or if

/// `kind` is [`ErrorKind::TorProtocolViolation`] and the runtime

/// protocol-warning mode is set to [`ProtocolWarningMode::Warn`].

#[doc(hidden)]

#[inline]

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, or

/// if the runtime protocol-warning policy is active and the error's kind is

/// [`ErrorKind::TorProtocolViolation`], we log it at `WARN` when the requested

/// level is lower than `WARN`.

///

/// # 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;

            let kind = err.kind();

            if tr::Level::WARN < $level && tr::__should_promote_to_warn(kind) {

                $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_time_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 std::sync::Mutex;

    use thiserror::Error;

    use tracing_test::traced_test;

    static PROTOCOL_MODE_TEST_LOCK: Mutex<()> = Mutex::new(());

    #[test]

    fn protocol_warning_mode_roundtrip_and_fallback() {

        let _lock = PROTOCOL_MODE_TEST_LOCK.lock().expect("poisoned mutex");

        struct RestoreMode(super::ProtocolWarningMode);

        impl Drop for RestoreMode {

            fn drop(&mut self) {

                super::set_protocol_warning_mode(self.0);

            }

        }

        let original = super::protocol_warning_mode();

        let _restore = RestoreMode(original);

        super::set_protocol_warning_mode(super::ProtocolWarningMode::Off);

        assert_eq!(

            super::protocol_warning_mode(),

            super::ProtocolWarningMode::Off

        );

        super::set_protocol_warning_mode(super::ProtocolWarningMode::Warn);

        assert_eq!(

            super::protocol_warning_mode(),

            super::ProtocolWarningMode::Warn

        );

        super::PROTOCOL_WARNING_MODE.store(u8::MAX, std::sync::atomic::Ordering::Relaxed);

        assert_eq!(

            super::protocol_warning_mode(),

            super::ProtocolWarningMode::Off

        );

    }

    #[derive(Debug)]

    struct KindError(super::ErrorKind);

    impl std::fmt::Display for KindError {

        fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {

            write!(f, "kind error")

        }

    }

    impl std::error::Error for KindError {}

    impl crate::HasKind for KindError {

        fn kind(&self) -> super::ErrorKind {

            self.0

        }

    }

    #[test]

    #[traced_test]

    #[allow(clippy::cognitive_complexity)]

    fn event_report_protocol_warning_policy() {

        let _lock = PROTOCOL_MODE_TEST_LOCK.lock().expect("poisoned mutex");

        struct RestoreMode(super::ProtocolWarningMode);

        impl Drop for RestoreMode {

            fn drop(&mut self) {

                super::set_protocol_warning_mode(self.0);

            }

        }

        let original = super::protocol_warning_mode();

        let _restore = RestoreMode(original);

        let msg_off = "torproto-off-debug";

        super::set_protocol_warning_mode(super::ProtocolWarningMode::Off);

        let err = KindError(super::ErrorKind::TorProtocolViolation);

        debug_report!(err, "{msg_off}");

        let msg_warn = "torproto-warn-promoted";

        super::set_protocol_warning_mode(super::ProtocolWarningMode::Warn);

        let err = KindError(super::ErrorKind::TorProtocolViolation);

        debug_report!(err, "{msg_warn}");

        let msg_internal = "internal-always-warn";

        super::set_protocol_warning_mode(super::ProtocolWarningMode::Off);

        let err = KindError(super::ErrorKind::Internal);

        debug_report!(err, "{msg_internal}");

        let msg_other = "other-kind-stays-debug";

        super::set_protocol_warning_mode(super::ProtocolWarningMode::Warn);

        let err = KindError(super::ErrorKind::TorDirectoryUnusable);

        debug_report!(err, "{msg_other}");

        logs_assert(|lines: &[&str]| {

            let level_for = |needle: &str| {

                lines

                    .iter()

                    .find(|line| line.contains(needle))

                    .ok_or_else(|| format!("missing log line containing '{needle}'"))

                    .and_then(|line| {

                        line.split_whitespace()

                            .find(|tok| {

                                matches!(*tok, "TRACE" | "DEBUG" | "INFO" | "WARN" | "ERROR")

                            })

                            .ok_or_else(|| format!("could not parse level from line: {line}"))

                    })

            };

            let msg_off_level = level_for(msg_off)?;

            if msg_off_level != "DEBUG" {

                return Err(format!(

                    "expected DEBUG for '{msg_off}', got {msg_off_level}"

                ));

            }

            let msg_warn_level = level_for(msg_warn)?;

            if msg_warn_level != "WARN" {

                return Err(format!(

                    "expected WARN for '{msg_warn}', got {msg_warn_level}"

                ));

            }

            let msg_internal_level = level_for(msg_internal)?;

            if msg_internal_level != "WARN" {

                return Err(format!(

                    "expected WARN for '{msg_internal}', got {msg_internal_level}"

                ));

            }

            let msg_other_level = level_for(msg_other)?;

            if msg_other_level != "DEBUG" {

                return Err(format!(

                    "expected DEBUG for '{msg_other}', got {msg_other_level}"

                ));

            }

            Ok(())

        });

    }

    #[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);

    }

}