package tracing

import (
	"net/http"

	"github.com/go-logr/logr"
	"go.opentelemetry.io/contrib/instrumentation/net/http/otelhttp"
	"go.opentelemetry.io/otel/propagation"
)

// HTTPMiddleware returns middleware that opens a server span per request
// (named from the mux route pattern once routing has happened) and hands
// handlers a request context whose logf.FromContext logger is base enriched
// with the trace context. Incoming W3C traceparent headers are honored, so
// clients see their own trace continue into the operator. /healthz is never
// traced. With tracing disabled the middleware degrades to injecting base
// unenriched — handlers can rely on logf.FromContext either way.
func HTTPMiddleware(operation string, base logr.Logger, opts ...Option) func(http.Handler) http.Handler {
	o := newOptions(opts)
	return func(next http.Handler) http.Handler {
		inner := http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
			r2 := r.WithContext(ContextWithLogger(r.Context(), base))
			next.ServeHTTP(w, r2)
			// WithContext copies the request, so the mux recorded the matched
			// route on r2; surface it to otelhttp, which renames the span
			// from r.Pattern after the handler returns.
			r.Pattern = r2.Pattern
		})
		otelOpts := []otelhttp.Option{
			otelhttp.WithFilter(func(r *http.Request) bool { return r.URL.Path != "/healthz" }),
			// Explicit propagators: deterministic regardless of whether the
			// global propagator has been installed (tests, disabled tracing).
			otelhttp.WithPropagators(propagation.NewCompositeTextMapPropagator(
				propagation.TraceContext{}, propagation.Baggage{})),
		}
		if o.tp != nil {
			otelOpts = append(otelOpts, otelhttp.WithTracerProvider(o.tp))
		}
		return otelhttp.NewHandler(inner, operation, otelOpts...)
	}
}