saddle-core 0.1.1

use std::{fmt, sync::Arc};

macro_rules! string_id {
    ($name:ident) => {
        #[derive(Clone, Debug, Eq, Hash, Ord, PartialEq, PartialOrd)]
        pub struct $name(Arc<str>);

        impl $name {
            pub fn new(value: impl Into<Arc<str>>) -> Self {
                Self(value.into())
            }

            pub fn as_str(&self) -> &str {
                &self.0
            }
        }

        impl From<&str> for $name {
            fn from(value: &str) -> Self {
                Self::new(value)
            }
        }

        impl From<String> for $name {
            fn from(value: String) -> Self {
                Self::new(value)
            }
        }

        impl fmt::Display for $name {
            fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
                formatter.write_str(&self.0)
            }
        }
    };
}

string_id!(ApplicationId);
string_id!(ModuleId);
string_id!(ServiceId);
string_id!(OperationId);

#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub struct TraceId(u128);

impl TraceId {
    pub const fn from_u128(value: u128) -> Self {
        Self(value)
    }

    pub const fn as_u128(self) -> u128 {
        self.0
    }
}

impl fmt::Display for TraceId {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(formatter, "{:032x}", self.0)
    }
}

#[derive(Clone, Copy, Debug, Eq, Hash, PartialEq)]
pub struct SpanId(u64);

impl SpanId {
    pub const fn from_u64(value: u64) -> Self {
        Self(value)
    }

    pub const fn as_u64(self) -> u64 {
        self.0
    }
}

impl fmt::Display for SpanId {
    fn fmt(&self, formatter: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(formatter, "{:016x}", self.0)
    }
}

/// The minimum identity propagated through Service, DB and Observability in V1.
///
/// Deadline, cancellation and resource-budget fields are deliberately absent
/// until a version explicitly defines their behavior.
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct CallContext {
    application: ApplicationId,
    module: ModuleId,
    service: ServiceId,
    operation: OperationId,
    trace_id: TraceId,
    span_id: SpanId,
}

impl CallContext {
    pub fn new(
        application: ApplicationId,
        module: ModuleId,
        service: ServiceId,
        operation: OperationId,
        trace_id: TraceId,
        span_id: SpanId,
    ) -> Self {
        Self {
            application,
            module,
            service,
            operation,
            trace_id,
            span_id,
        }
    }

    pub fn application(&self) -> &ApplicationId {
        &self.application
    }

    pub fn module(&self) -> &ModuleId {
        &self.module
    }

    pub fn service(&self) -> &ServiceId {
        &self.service
    }

    pub fn operation(&self) -> &OperationId {
        &self.operation
    }

    pub const fn trace_id(&self) -> TraceId {
        self.trace_id
    }

    pub const fn span_id(&self) -> SpanId {
        self.span_id
    }
}

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

    #[test]
    fn identifiers_have_stable_display_forms() {
        assert_eq!(TraceId::from_u128(42).to_string().len(), 32);
        assert_eq!(SpanId::from_u64(42).to_string().len(), 16);
        assert_eq!(ServiceId::from("orders").to_string(), "orders");
    }
}