use opentelemetry::trace::TracerProvider as _;
use opentelemetry_appender_tracing::layer::{OpenTelemetryTracingBridge, TracingSpanAttributes};
use tracing_subscriber::EnvFilter;
use tracing_subscriber::layer::SubscriberExt;
use tracing_subscriber::util::SubscriberInitExt;

use crate::Telemetry;
use crate::config::TelemetryConfig;

pub fn install(config: &TelemetryConfig, telemetry: &Telemetry) {
    let base = std::env::var(EnvFilter::DEFAULT_ENV)
        .ok()
        .filter(|value| !value.trim().is_empty())
        .unwrap_or_else(|| config.log_filter.clone());
    // 连接池与查询执行器自身不产出业务日志，慢查询告警也与请求日志重复。
    // 默认静默，但配置里显式写了 sqlx 目标时以用户的选择为准，方便临时排查。
    let mut spec = base.clone();
    if !base.contains("sqlx") {
        spec.push_str(",sqlx=off");
    }
    // RocketMQ 客户端每 5s 打印一次定时任务、拉取与路由刷新，属于库内部心跳。
    // 默认只保留 warn 及以上：路由缺失、连接异常照样可见，周期性噪音不再进日志。
    if !base.contains("rocketmq") {
        spec.push_str(",rocketmq_client_rust=warn,rocketmq_transport=warn");
    }
    let filter =
        EnvFilter::try_new(&spec).unwrap_or_else(|_| EnvFilter::new(config.log_filter.as_str()));
    let tracer = telemetry
        .tracer_provider()
        .tracer(config.service_name.clone());
    let trace_layer = tracing_opentelemetry::layer().with_tracer(tracer);
    let log_layer = OpenTelemetryTracingBridge::builder(telemetry.logger_provider())
        .with_tracing_span_attributes(TracingSpanAttributes::allowlist(["request_id"]))
        .build();
    let format_layer = tracing_subscriber::fmt::layer()
        .with_target(true)
        .with_writer(OutputWriter {
            enabled: config.stdout,
        });

    let result = tracing_subscriber::registry()
        .with(filter)
        .with(format_layer)
        .with(trace_layer)
        .with(log_layer)
        .try_init();

    if let Err(error) = result {
        tracing::warn!(%error, "tracing subscriber already installed");
    }

    for warning in telemetry.warnings() {
        tracing::warn!("{warning}");
    }
}

#[derive(Debug, Clone, Copy)]
struct OutputWriter {
    enabled: bool,
}

impl<'a> tracing_subscriber::fmt::MakeWriter<'a> for OutputWriter {
    type Writer = Box<dyn std::io::Write + 'a>;

    fn make_writer(&'a self) -> Self::Writer {
        if self.enabled {
            Box::new(std::io::stdout())
        } else {
            Box::new(std::io::sink())
        }
    }
}