use opentelemetry::KeyValue;
use opentelemetry_sdk::Resource;

use crate::config::TelemetryConfig;

pub fn build(config: &TelemetryConfig) -> Resource {
    let mut attributes = Vec::with_capacity(config.attributes.len() + 4);
    attributes.push(KeyValue::new("service.name", config.service_name.clone()));

    if let Some(version) = &config.service_version {
        attributes.push(KeyValue::new("service.version", version.clone()));
    }
    if let Some(environment) = &config.environment {
        attributes.push(KeyValue::new("deployment.environment", environment.clone()));
    }
    for (key, value) in &config.attributes {
        if key == "service.name" {
            continue;
        }
        attributes.push(KeyValue::new(key.clone(), value.clone()));
    }
    if let Some(host) = {
        std::env::var("HOSTNAME")
            .ok()
            .filter(|value| !value.is_empty())
            .or_else(|| {
                std::env::var("COMPUTERNAME")
                    .ok()
                    .filter(|value| !value.is_empty())
            })
    } {
        attributes.push(KeyValue::new("host.name", host));
    }

    Resource::builder_empty()
        .with_attributes(attributes)
        .build()
}