package runner

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"log/slog"

	"queryorchestration/internal/serviceconfig/queue"

	"github.com/aws/aws-sdk-go-v2/service/sqs/types"
)

type Server[B any] struct {
	cleanup func() error
	cfg     ConfigProvider[B]
}

func (c *Server[B]) Listen(ctx context.Context) {
	slog.Info("Listening to queue")
	defer func() {
		if err := c.cleanup(); err != nil {
			fmt.Printf("Error during cleanup: %v", err)
		}
	}()

	for {
		select {
		case <-ctx.Done():
			return
		default:
			err := c.pollMessage(ctx)
			if err != nil {
				slog.Error(err.Error())
			}
		}
	}
}

func (c *Server[B]) pollMessage(ctx context.Context) error {
	result, err := c.cfg.ReceiveFromQueue(ctx, &queue.ReceiveParams{
		QueueURL: c.cfg.GetQueueURL(),
	})
	if err != nil {
		return fmt.Errorf("message fetch fail: %w", err)
	}

	for _, message := range result.Messages {
		err := c.processMessage(ctx, &message)
		if err != nil {
			slog.Error("message process fail", "id", *message.MessageId, "err", err)
		}
	}

	return nil
}

func (c *Server[B]) processMessage(ctx context.Context, message *types.Message) error {
	body := c.processBody(message)
	if body == nil {
		return nil
	}

	slog.Debug("processing message", "id", *message.MessageId, "body", *message.Body)

	isProcessed := c.cfg.GetController().Process(ctx, *body)
	if !isProcessed {
		return errors.New("message process fail")
	}

	err := c.cfg.DeleteFromQueue(ctx, &queue.DeleteParams{
		QueueURL:      c.cfg.GetQueueURL(),
		ReceiptHandle: message.ReceiptHandle,
	})
	if err != nil {
		return fmt.Errorf("message delete fail: %w", err)
	}

	return nil
}

func (c *Server[B]) processBody(message *types.Message) *B {
	if message == nil {
		slog.Error("nil message")
		return nil
	} else if message.MessageId == nil {
		slog.Error("nil message id")
		return nil
	} else if message.Body == nil {
		slog.Error("nil body", "messageId", *message.MessageId)
		return nil
	}

	var body B
	err := json.Unmarshal([]byte(*message.Body), &body)
	if err != nil {
		slog.Error("parsing body", "messageId", *message.MessageId, "body", *message.Body)
		return nil
	}

	err = c.cfg.GetValidator().Struct(body)
	if err != nil {
		slog.Error("invalid body", "messageId", *message.MessageId, "error", err)
		return nil
	}

	return &body
}