package telemetry

import (
	"context"
	"log/slog"
	"os"

	"git.kmsign.ru/royalcat/tstor/pkg/rlog"
	"github.com/agoda-com/opentelemetry-go/otelslog"
	"github.com/agoda-com/opentelemetry-logs-go/exporters/otlp/otlplogs"
	"github.com/agoda-com/opentelemetry-logs-go/exporters/otlp/otlplogs/otlplogshttp"
	logsdk "github.com/agoda-com/opentelemetry-logs-go/sdk/logs"
	"go.opentelemetry.io/otel"
	"go.opentelemetry.io/otel/exporters/otlp/otlptrace/otlptracehttp"
	"go.opentelemetry.io/otel/exporters/prometheus"
	"go.opentelemetry.io/otel/sdk/metric"
	"go.opentelemetry.io/otel/sdk/resource"
	"go.opentelemetry.io/otel/sdk/trace"
	semconv "go.opentelemetry.io/otel/semconv/v1.24.0"
)

type Client struct {
	log *slog.Logger

	tracerProvider *trace.TracerProvider
	metricProvider *metric.MeterProvider
	loggerProvider *logsdk.LoggerProvider
}

func (client *Client) Shutdown(ctx context.Context) {
	log := rlog.FunctionLog(client.log, "Shutdown")
	if client.metricProvider == nil {
		err := client.metricProvider.Shutdown(ctx)
		if err != nil {
			log.Error("error shutting down metric provider", rlog.Err(err))
		}
	}
	if client.tracerProvider == nil {
		err := client.tracerProvider.Shutdown(ctx)
		if err != nil {
			log.Error("error shutting down tracer provider", rlog.Err(err))
		}
	}
	if client.loggerProvider == nil {
		err := client.loggerProvider.Shutdown(ctx)
		if err != nil {
			log.Error("error shutting down logger provider", rlog.Err(err))
		}
	}
}

const appName = "tstor"

func Setup(ctx context.Context, endpoint string) (*Client, error) {
	log := rlog.ComponentLog("telemetry")

	client := &Client{
		log: log,
	}
	otel.SetErrorHandler(otel.ErrorHandlerFunc(func(cause error) {
		log.Error("otel error", rlog.Err(cause))
	}))

	hostName, _ := os.Hostname()

	r, err := resource.Merge(
		resource.Default(),
		resource.NewWithAttributes(
			semconv.SchemaURL,
			semconv.ServiceName(appName),
			semconv.HostName(hostName),
		),
	)
	if err != nil {
		return nil, err
	}

	metricExporter, err := prometheus.New(prometheus.WithNamespace(appName))
	if err != nil {
		return nil, err
	}
	client.metricProvider = metric.NewMeterProvider(
		metric.WithReader(metricExporter),
		metric.WithResource(r),
	)
	otel.SetMeterProvider(client.metricProvider)
	log.Info("prometheus metrics provider initialized")

	traceExporter, err := otlptracehttp.New(ctx,
		otlptracehttp.WithEndpoint(endpoint),
		otlptracehttp.WithRetry(otlptracehttp.RetryConfig{
			Enabled: false,
		}),
	)
	if err != nil {
		return nil, err
	}
	client.tracerProvider = trace.NewTracerProvider(
		trace.WithBatcher(traceExporter),
		trace.WithResource(r),
	)
	otel.SetTracerProvider(client.tracerProvider)
	log.Info("otel tracing provider initialized")

	logExporter, err := otlplogs.NewExporter(ctx,
		otlplogs.WithClient(
			otlplogshttp.NewClient(otlplogshttp.WithEndpoint(endpoint)),
		),
	)
	if err != nil {
		return nil, err
	}
	client.loggerProvider = logsdk.NewLoggerProvider(
		logsdk.WithBatcher(logExporter),
		logsdk.WithResource(r),
	)

	rlog.AddHandler(otelslog.NewOtelHandler(client.loggerProvider,
		&otelslog.HandlerOptions{
			Level: slog.LevelDebug,
		}),
	)
	client.log = slog.Default()

	return client, nil
}