package deliver

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

	"github.com/redis/go-redis/v9"

	"spark-server/internal/pkg/errs"
)

type redisQueue struct {
	rdb        *redis.Client
	queueKey   string
	processKey string
}

func NewRedisQueue(rdb *redis.Client, queueKey, processKey string) Queue {
	return &redisQueue{rdb: rdb, queueKey: queueKey, processKey: processKey}
}

func (q *redisQueue) Push(ctx context.Context, job *Job) error {
	if q.rdb == nil {
		return errs.ErrInternal
	}
	raw, err := json.Marshal(job)
	if err != nil {
		return err
	}
	return q.rdb.RPush(ctx, q.queueKey, raw).Err()
}

func (q *redisQueue) Take(ctx context.Context, timeout time.Duration) (*Job, error) {
	if q.rdb == nil {
		return nil, errs.ErrInternal
	}
	res, err := q.rdb.BRPopLPush(ctx, q.queueKey, q.processKey, timeout).Result()
	if err == redis.Nil {
		return nil, nil
	}
	if err != nil {
		return nil, err
	}
	job := &Job{}
	if err := json.Unmarshal([]byte(res), job); err != nil {
		return nil, fmt.Errorf("deliver job: %w", err)
	}
	return job, nil
}

func (q *redisQueue) Ack(ctx context.Context, job *Job) error {
	if q.rdb == nil || job == nil {
		return nil
	}
	raw, err := json.Marshal(job)
	if err != nil {
		return err
	}
	return q.rdb.LRem(ctx, q.processKey, 1, raw).Err()
}

func (q *redisQueue) RequeueStale(ctx context.Context) error {
	if q.rdb == nil {
		return nil
	}
	for {
		res, err := q.rdb.RPopLPush(ctx, q.processKey, q.queueKey).Result()
		if err == redis.Nil {
			return nil
		}
		if err != nil {
			return err
		}
		_ = res
	}
}