package redis

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

	goredis "github.com/redis/go-redis/v9"
	"stream.api/internal/database/model"
	"stream.api/internal/dto"
)

const (
	JobQueueKey        = "render:jobs:queue:v2"
	JobInflightKey     = "render:jobs:inflight"
	JobInflightMetaKey = "render:jobs:inflight:meta"
	JobSequenceKey     = "render:jobs:queue:seq"
	LogChannel         = "render:jobs:logs"
	ResourceChannel    = "render:agents:resources"
	JobUpdateChannel   = "render:jobs:updates"
	defaultQueuePoll   = time.Second
	defaultInflightTTL = 15 * time.Minute
)

type RedisAdapter struct{ client *goredis.Client }

type inflightMeta struct {
	ReadyScore float64 `json:"ready_score"`
	ClaimedAt  int64   `json:"claimed_at"`
}

func NewAdapter(addr, password string, db int) (*RedisAdapter, error) {
	client := goredis.NewClient(&goredis.Options{Addr: addr, Password: password, DB: db})
	if err := client.Ping(context.Background()).Err(); err != nil {
		return nil, err
	}
	return &RedisAdapter{client: client}, nil
}

func (r *RedisAdapter) Client() *goredis.Client { return r.client }

func (r *RedisAdapter) Enqueue(ctx context.Context, job *model.Job) error {
	if job == nil || strings.TrimSpace(job.ID) == "" {
		return errors.New("job id is required")
	}
	priority := int64(0)
	if job.Priority != nil {
		priority = *job.Priority
	}
	seq, err := r.client.Incr(ctx, JobSequenceKey).Result()
	if err != nil {
		return err
	}
	score := float64((-priority * 1_000_000_000_000) + seq)
	jobID := strings.TrimSpace(job.ID)
	if err := r.client.HDel(ctx, JobInflightMetaKey, jobID).Err(); err != nil {
		return err
	}
	if err := r.client.ZRem(ctx, JobInflightKey, jobID).Err(); err != nil {
		return err
	}
	return r.client.ZAdd(ctx, JobQueueKey, goredis.Z{Score: score, Member: jobID}).Err()
}

func (r *RedisAdapter) Dequeue(ctx context.Context) (*model.Job, error) {
	for {
		if ctx.Err() != nil {
			return nil, ctx.Err()
		}
		res, err := r.client.ZPopMin(ctx, JobQueueKey, 1).Result()
		if err != nil {
			if ctx.Err() != nil {
				return nil, ctx.Err()
			}
			return nil, err
		}
		if len(res) == 0 {
			select {
			case <-ctx.Done():
				return nil, ctx.Err()
			case <-time.After(defaultQueuePoll):
				continue
			}
		}
		jobID := fmt.Sprintf("%v", res[0].Member)
		meta, err := json.Marshal(inflightMeta{ReadyScore: res[0].Score, ClaimedAt: time.Now().Unix()})
		if err != nil {
			return nil, err
		}
		leaseScore := float64(time.Now().Add(defaultInflightTTL).Unix())
		pipe := r.client.TxPipeline()
		pipe.ZAdd(ctx, JobInflightKey, goredis.Z{Score: leaseScore, Member: jobID})
		pipe.HSet(ctx, JobInflightMetaKey, jobID, meta)
		if _, err := pipe.Exec(ctx); err != nil {
			return nil, err
		}
		return &model.Job{ID: jobID}, nil
	}
}

func (r *RedisAdapter) Ack(ctx context.Context, jobID string) error {
	jobID = strings.TrimSpace(jobID)
	if jobID == "" {
		return nil
	}
	pipe := r.client.TxPipeline()
	pipe.ZRem(ctx, JobQueueKey, jobID)
	pipe.ZRem(ctx, JobInflightKey, jobID)
	pipe.HDel(ctx, JobInflightMetaKey, jobID)
	_, err := pipe.Exec(ctx)
	return err
}

func (r *RedisAdapter) ListExpiredInflight(ctx context.Context, now time.Time, limit int64) ([]string, error) {
	if limit <= 0 {
		limit = 100
	}
	return r.client.ZRangeByScore(ctx, JobInflightKey, &goredis.ZRangeBy{Min: "-inf", Max: fmt.Sprintf("%d", now.Unix()), Offset: 0, Count: limit}).Result()
}

func (r *RedisAdapter) TouchInflight(ctx context.Context, jobID string, ttl time.Duration) error {
	jobID = strings.TrimSpace(jobID)
	if jobID == "" {
		return nil
	}
	if ttl <= 0 {
		ttl = defaultInflightTTL
	}
	return r.client.ZAddXX(ctx, JobInflightKey, goredis.Z{Score: float64(time.Now().Add(ttl).Unix()), Member: jobID}).Err()
}

func (r *RedisAdapter) Publish(ctx context.Context, jobID string, logLine string, progress float64) error {
	payload, err := json.Marshal(dto.LogEntry{JobID: jobID, Line: logLine, Progress: progress})
	if err != nil {
		return err
	}
	return r.client.Publish(ctx, LogChannel, payload).Err()
}

func (r *RedisAdapter) Subscribe(ctx context.Context, jobID string) (<-chan dto.LogEntry, error) {
	pubsub := r.client.Subscribe(ctx, LogChannel)
	ch := make(chan dto.LogEntry)
	go func() {
		defer close(ch)
		defer pubsub.Close()
		for msg := range pubsub.Channel() {
			var entry dto.LogEntry
			if err := json.Unmarshal([]byte(msg.Payload), &entry); err != nil {
				continue
			}
			if jobID == "" || entry.JobID == jobID {
				ch <- entry
			}
		}
	}()
	return ch, nil
}

func (r *RedisAdapter) PublishResource(ctx context.Context, agentID string, data []byte) error {
	var decoded struct {
		CPU float64 `json:"cpu"`
		RAM float64 `json:"ram"`
	}
	if err := json.Unmarshal(data, &decoded); err != nil {
		return err
	}
	payload, err := json.Marshal(dto.SystemResource{AgentID: agentID, CPU: decoded.CPU, RAM: decoded.RAM})
	if err != nil {
		return err
	}
	return r.client.Publish(ctx, ResourceChannel, payload).Err()
}

func (r *RedisAdapter) SubscribeResources(ctx context.Context) (<-chan dto.SystemResource, error) {
	pubsub := r.client.Subscribe(ctx, ResourceChannel)
	ch := make(chan dto.SystemResource)
	go func() {
		defer close(ch)
		defer pubsub.Close()
		for msg := range pubsub.Channel() {
			var entry dto.SystemResource
			if err := json.Unmarshal([]byte(msg.Payload), &entry); err != nil {
				continue
			}
			ch <- entry
		}
	}()
	return ch, nil
}

func (r *RedisAdapter) PublishCancel(ctx context.Context, agentID string, jobID string) error {
	return r.client.Publish(ctx, fmt.Sprintf("render:agents:%s:cancel", agentID), jobID).Err()
}

func (r *RedisAdapter) SubscribeCancel(ctx context.Context, agentID string) (<-chan string, error) {
	pubsub := r.client.Subscribe(ctx, fmt.Sprintf("render:agents:%s:cancel", agentID))
	ch := make(chan string)
	go func() {
		defer close(ch)
		defer pubsub.Close()
		for msg := range pubsub.Channel() {
			ch <- msg.Payload
		}
	}()
	return ch, nil
}

func (r *RedisAdapter) PublishJobUpdate(ctx context.Context, jobID string, status string, videoID string) error {
	payload, err := json.Marshal(map[string]string{"job_id": jobID, "status": status, "video_id": videoID})
	if err != nil {
		return err
	}
	return r.client.Publish(ctx, JobUpdateChannel, payload).Err()
}

func (r *RedisAdapter) SubscribeJobUpdates(ctx context.Context) (<-chan string, error) {
	pubsub := r.client.Subscribe(ctx, JobUpdateChannel)
	ch := make(chan string)
	go func() {
		defer close(ch)
		defer pubsub.Close()
		for msg := range pubsub.Channel() {
			ch <- msg.Payload
		}
	}()
	return ch, nil
}

func (c *RedisAdapter) Set(ctx context.Context, key string, value interface{}, expiration time.Duration) error {
	return c.client.Set(ctx, key, value, expiration).Err()
}

func (c *RedisAdapter) Get(ctx context.Context, key string) (string, error) {
	return c.client.Get(ctx, key).Result()
}

func (c *RedisAdapter) Del(ctx context.Context, key string) error {
	return c.client.Del(ctx, key).Err()
}

func (c *RedisAdapter) Close() error {
	return c.client.Close()
}