package observability

import (
	"context"
	"fmt"
	"log/slog"
	"os"
	"strconv"
	"strings"
	"time"

	"gl/infrastructure/config"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/attribute"
	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracegrpc"
	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
	"go.opentelemetry.io/otel/propagation"
	"go.opentelemetry.io/otel/sdk/resource"
	sdktrace "go.opentelemetry.io/otel/sdk/trace"
)

// Setup configures tracing without making telemetry availability a startup dependency.
func Setup(ctx context.Context, cfg config.TelemetryConfig, service, environment string) func(context.Context) {
	if value := os.Getenv("OTEL_SERVICE_NAME"); value != "" { service = value }
	if value := os.Getenv("OTEL_EXPORTER_OTLP_TRACES_ENDPOINT"); value != "" { cfg.Endpoint = value } else if value := os.Getenv("OTEL_EXPORTER_OTLP_ENDPOINT"); value != "" { cfg.Endpoint = value }
	if value := os.Getenv("OTEL_EXPORTER_OTLP_PROTOCOL"); value != "" { cfg.Protocol = value }
	if value := os.Getenv("OTEL_TRACES_SAMPLER"); value != "" { cfg.Sampler = value }; if value := os.Getenv("OTEL_TRACES_SAMPLER_ARG"); value != "" { cfg.SamplerArg = value }
	otel.SetTextMapPropagator(propagation.NewCompositeTextMapPropagator(propagation.TraceContext{}, propagation.Baggage{}))
	if !cfg.Enabled || cfg.Endpoint == "" || (cfg.Protocol != "grpc" && cfg.Protocol != "http/protobuf") { if cfg.Enabled { slog.Warn("OpenTelemetry disabled due to invalid configuration") }; return func(context.Context) {} }
	var exp sdktrace.SpanExporter; var err error
	if cfg.Protocol == "grpc" { options := []otlptracegrpc.Option{otlptracegrpc.WithEndpoint(cfg.Endpoint), otlptracegrpc.WithTimeout(timeout(cfg.ExportTimeout)), otlptracegrpc.WithHeaders(cfg.Headers)}; if cfg.Insecure { options = append(options, otlptracegrpc.WithInsecure()) }; exp, err = otlptracegrpc.New(ctx, options...) } else { options := []otlptracehttp.Option{otlptracehttp.WithEndpoint(cfg.Endpoint), otlptracehttp.WithTimeout(timeout(cfg.ExportTimeout)), otlptracehttp.WithHeaders(cfg.Headers)}; if cfg.Insecure { options = append(options, otlptracehttp.WithInsecure()) }; exp, err = otlptracehttp.New(ctx, options...) }
	if err != nil { slog.Warn("OpenTelemetry exporter unavailable; tracing disabled", "error", err); return func(context.Context) {} }
	host, _ := os.Hostname(); res, err := resource.New(ctx, resource.WithAttributes(attribute.String("service.name", service), attribute.String("service.namespace", "darano"), attribute.String("deployment.environment.name", environment), attribute.String("host.name", host))); if err != nil { slog.Warn("OpenTelemetry resource setup failed", "error", err); return func(context.Context) {} }
	ratio, parseErr := strconv.ParseFloat(cfg.SamplerArg, 64); if cfg.Sampler == "parentbased_traceidratio" && (parseErr != nil || ratio < 0 || ratio > 1) { slog.Warn("OpenTelemetry disabled due to invalid sampler", "error", fmt.Errorf("invalid sampler-arg")); return func(context.Context) {} }
	provider := sdktrace.NewTracerProvider(sdktrace.WithResource(res), sdktrace.WithSampler(sdktrace.ParentBased(sdktrace.TraceIDRatioBased(ratio))), sdktrace.WithBatcher(exp, sdktrace.WithMaxQueueSize(2048), sdktrace.WithBatchTimeout(timeout(cfg.BatchTimeout)), sdktrace.WithExportTimeout(timeout(cfg.ExportTimeout))))
	otel.SetTracerProvider(provider); return func(stop context.Context) { stop, cancel := context.WithTimeout(stop, timeout(cfg.ShutdownTimeout)); defer cancel(); if err := provider.Shutdown(stop); err != nil { slog.Warn("OpenTelemetry shutdown failed", "error", err) } }
}
func timeout(value time.Duration) time.Duration { if value > 0 { return value }; return 5*time.Second }
var _ = strings.TrimSpace