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// Copyright 2019-2024 ChainSafe Systems
// SPDX-License-Identifier: Apache-2.0, MIT

use git_version::git_version;
use once_cell::sync::Lazy;
use prometheus_client::{
    collector::Collector,
    encoding::{DescriptorEncoder, EncodeLabelSet, EncodeMetric},
    metrics::{family::Family, gauge::Gauge},
};

/// Current git commit hash of the Forest repository.
pub const GIT_HASH: &str =
    git_version!(args = ["--always", "--exclude", "*"], fallback = "unknown");

/// Current version of the Forest repository with git hash embedded
/// E.g., `0.8.0+git.e69baf3e4`
pub static FOREST_VERSION_STRING: Lazy<String> =
    Lazy::new(|| format!("{}+git.{}", env!("CARGO_PKG_VERSION"), GIT_HASH));

pub static FOREST_VERSION: Lazy<semver::Version> =
    Lazy::new(|| semver::Version::parse(env!("CARGO_PKG_VERSION")).expect("Invalid version"));

#[derive(Clone, Debug, Hash, PartialEq, Eq, EncodeLabelSet)]
pub struct VersionLabel {
    version: &'static str,
}

impl VersionLabel {
    pub const fn new(version: &'static str) -> Self {
        Self { version }
    }
}

#[derive(Debug)]
pub struct ForestVersionCollector {
    version: Family<VersionLabel, Gauge>,
}

impl ForestVersionCollector {
    pub fn new() -> Self {
        Self {
            version: Family::default(),
        }
    }
}

impl Collector for ForestVersionCollector {
    fn encode(&self, mut encoder: DescriptorEncoder) -> Result<(), std::fmt::Error> {
        let metric_encoder = encoder.encode_descriptor(
            "build_info",
            "semantic version of the forest binary",
            None,
            self.version.metric_type(),
        )?;
        self.version
            .get_or_create(&VersionLabel::new(FOREST_VERSION_STRING.as_str()))
            .set(1);
        self.version.encode(metric_encoder)?;
        Ok(())
    }
}