package logger

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

	"go.opentelemetry.io/otel/trace"
)

type contextKey string

const requestIDKey contextKey = "request_id"

// New creates a logger with the specified format (json or text) and level.
func New(format string, level string) *slog.Logger {
	var handler slog.Handler

	logLevel := parseLevel(level)
	opts := &slog.HandlerOptions{
		Level:     logLevel,
		AddSource: true, // Add file:line info for debugging
	}

	if format == "json" {
		handler = slog.NewJSONHandler(os.Stdout, opts)
	} else {
		handler = slog.NewTextHandler(os.Stdout, opts)
	}

	return slog.New(handler)
}

// parseLevel converts a string level to slog.Level.
func parseLevel(level string) slog.Level {
	switch level {
	case "debug":
		return slog.LevelDebug
	case "info":
		return slog.LevelInfo
	case "warn":
		return slog.LevelWarn
	case "error":
		return slog.LevelError
	default:
		return slog.LevelInfo
	}
}

// WithRequestID adds a request ID to the context for tracing.
func WithRequestID(ctx context.Context, requestID string) context.Context {
	return context.WithValue(ctx, requestIDKey, requestID)
}

// FromContext extracts the request ID from context, or returns empty string.
func FromContext(ctx context.Context) string {
	if id, ok := ctx.Value(requestIDKey).(string); ok {
		return id
	}
	return ""
}

// LogAttrsWithTrace adds trace context to log attributes for correlation.
func LogAttrsWithTrace(ctx context.Context, attrs ...any) []any {
	spanCtx := trace.SpanFromContext(ctx).SpanContext()
	if spanCtx.IsValid() {
		attrs = append(attrs,
			slog.String("trace_id", spanCtx.TraceID().String()),
			slog.String("span_id", spanCtx.SpanID().String()),
		)
	}
	return attrs
}