package zset

import (
	"context"
	"strings"

	"github.com/gogf/gf/v2/container/gvar"
	"github.com/gogf/gf/v2/errors/gerror"
)

var ErrProducerLeaseLost = gerror.New("producer lease lost")

// WithIMEIProducerLease returns a private producer view; the shared store and
// other producer/consumer protocols are unchanged. The IMEI caller must reject
// Redis Cluster before using this view: the global lock and run keys cross slots.
func (s *Store) WithIMEIProducerLease(key, owner, runID string) (*Store, error) {
	if key == "" || owner == "" || runID == "" {
		return nil, gerror.New("producer lease key, owner and runId are required")
	}
	view := *s
	view.redis = &imeiProducerRedis{RedisClient: s.redis, key: key, owner: owner, runID: runID}
	return &view, nil
}

type imeiProducerRedis struct {
	RedisClient
	key, owner, runID string
}

func (r *imeiProducerRedis) Eval(ctx context.Context, script string, numKeys int64, keys []string, args []any) (*gvar.Var, error) {
	leaseKeys := append(append([]string(nil), keys...), r.key)
	leaseArgs := append(append([]any(nil), args...), r.owner, r.runID)
	result, err := r.RedisClient.Eval(ctx, imeiProducerLeaseGuard+script, numKeys+1, leaseKeys, leaseArgs)
	if err != nil && strings.Contains(err.Error(), "IMEI_PRODUCER_LEASE_LOST") {
		return nil, gerror.Wrap(ErrProducerLeaseLost, "reject stale IMEI producer write")
	}
	return result, err
}

func (r *imeiProducerRedis) Do(ctx context.Context, command string, args ...any) (*gvar.Var, error) {
	switch strings.ToUpper(command) {
	case "HGETALL", "SMEMBERS": // The producer's metadata/capacity reads are not mutations.
		return r.RedisClient.Do(ctx, command, args...)
	case "SADD", "HSET": // CreateRun also writes the index and metadata extensions.
		commandArgs := append([]any{command}, args...)
		return r.Eval(ctx, "return redis.call(unpack(ARGV))", 0, nil, commandArgs)
	default:
		return nil, gerror.Newf("unsupported command in IMEI producer lease view: %s", command)
	}
}

// Remove guard-only arguments before executing the original queue script, so
// task-pair loops and key indexing retain their original semantics.
const imeiProducerLeaseGuard = `
local leaseRunID = table.remove(ARGV)
local leaseOwner = table.remove(ARGV)
local leaseKey = table.remove(KEYS)
local current = redis.call('GET', leaseKey)
if not current then return redis.error_reply('IMEI_PRODUCER_LEASE_LOST') end
local ok, lease = pcall(cjson.decode, current)
if not ok or type(lease) ~= 'table' or lease['owner'] ~= leaseOwner or lease['runId'] ~= leaseRunID then
 return redis.error_reply('IMEI_PRODUCER_LEASE_LOST')
end
`