// Package logging configures the Mail Service process logger and provides
// context-aware helpers for trace, delivery, attempt, and command fields.
package logging

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

	"galaxy/mail/internal/api/streamcommand"
	"galaxy/mail/internal/domain/attempt"
	deliverydomain "galaxy/mail/internal/domain/delivery"

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

// New constructs the process-wide JSON logger from level.
func New(level string) (*slog.Logger, error) {
	var slogLevel slog.Level
	if err := slogLevel.UnmarshalText([]byte(strings.TrimSpace(level))); err != nil {
		return nil, fmt.Errorf("build logger: %w", err)
	}

	return slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{
		Level: slogLevel,
	})), nil
}

// TraceAttrsFromContext returns slog key-value pairs for the active
// OpenTelemetry span when ctx carries a valid span context.
func TraceAttrsFromContext(ctx context.Context) []any {
	if ctx == nil {
		return nil
	}

	spanContext := trace.SpanContextFromContext(ctx)
	if !spanContext.IsValid() {
		return nil
	}

	return []any{
		"otel_trace_id", spanContext.TraceID().String(),
		"otel_span_id", spanContext.SpanID().String(),
	}
}

// DeliveryAttrs returns structured delivery-identifying log fields.
func DeliveryAttrs(record deliverydomain.Delivery) []any {
	attrs := []any{
		"delivery_id", record.DeliveryID.String(),
		"source", string(record.Source),
	}
	if !record.TemplateID.IsZero() {
		attrs = append(attrs, "template_id", record.TemplateID.String())
	}

	return attrs
}

// AttemptAttrs returns structured attempt-identifying log fields.
func AttemptAttrs(record attempt.Attempt) []any {
	return []any{
		"delivery_id", record.DeliveryID.String(),
		"attempt_no", record.AttemptNo,
	}
}

// DeliveryAttemptAttrs returns structured delivery and attempt fields.
func DeliveryAttemptAttrs(deliveryRecord deliverydomain.Delivery, attemptRecord attempt.Attempt) []any {
	attrs := DeliveryAttrs(deliveryRecord)
	attrs = append(attrs, "attempt_no", attemptRecord.AttemptNo)
	return attrs
}

// CommandAttrs returns structured generic-command log fields.
func CommandAttrs(command streamcommand.Command) []any {
	attrs := []any{
		"delivery_id", command.DeliveryID.String(),
		"source", string(command.Source),
	}
	if !command.TemplateID.IsZero() {
		attrs = append(attrs, "template_id", command.TemplateID.String())
	}
	if strings.TrimSpace(command.TraceID) != "" {
		attrs = append(attrs, "trace_id", command.TraceID)
	}

	return attrs
}