package telemetry

import (
	"context"
	"encoding/json"
	"time"

	otellog "go.opentelemetry.io/otel/log"
	sdklog "go.opentelemetry.io/otel/sdk/log"
)

// LogBridge implements io.Writer and forwards zerolog JSON lines to the
// OTel LoggerProvider. It is used as an extra writer in zerolog's MultiWriter
// so that logs go to both file and OTLP.
type LogBridge struct {
	provider *sdklog.LoggerProvider
}

func (b *LogBridge) Write(p []byte) (n int, err error) {
	var entry map[string]interface{}
	if err := json.Unmarshal(p, &entry); err != nil {
		return len(p), nil // skip malformed lines
	}

	logger := b.provider.Logger("zerolog")

	var rec otellog.Record
	rec.SetTimestamp(time.Now())

	if msg, ok := entry["message"].(string); ok {
		rec.SetBody(otellog.StringValue(msg))
	}

	if lvl, ok := entry["level"].(string); ok {
		rec.SetSeverity(mapSeverity(lvl))
	}

	// Forward all fields as attributes
	attrs := make([]otellog.KeyValue, 0, len(entry))
	for k, v := range entry {
		if k == "message" || k == "level" || k == "time" {
			continue
		}
		switch val := v.(type) {
		case string:
			attrs = append(attrs, otellog.String(k, val))
		case float64:
			attrs = append(attrs, otellog.Float64(k, val))
		case bool:
			attrs = append(attrs, otellog.Bool(k, val))
		default:
			b, _ := json.Marshal(val)
			attrs = append(attrs, otellog.String(k, string(b)))
		}
	}
	rec.AddAttributes(attrs...)

	logger.Emit(context.Background(), rec)
	return len(p), nil
}

func mapSeverity(level string) otellog.Severity {
	switch level {
	case "trace":
		return otellog.SeverityTrace
	case "debug":
		return otellog.SeverityDebug
	case "info":
		return otellog.SeverityInfo
	case "warn", "warning":
		return otellog.SeverityWarn
	case "error":
		return otellog.SeverityError
	case "fatal":
		return otellog.SeverityFatal
	case "panic":
		return otellog.SeverityFatal2
	default:
		return otellog.SeverityInfo
	}
}