package model

import (
	"context"
	"errors"
	"fmt"

	"modelRT/common"
	"modelRT/constants"

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

// DataObjectRedisAliasKey returns the Redis string key used to resolve any
// supported token form to the one canonical full-token hash.
func DataObjectRedisAliasKey(dataObjectType constants.DataObjectType, token string) (string, error) {
	switch dataObjectType {
	case constants.DataObjectTypeParameter:
		return constants.RedisParameterDataObjectAliasPrefix + token, nil
	case constants.DataObjectTypeMeasurement:
		return constants.RedisMeasurementDataObjectAliasPrefix + token, nil
	default:
		return "", fmt.Errorf("unsupported data object type %q", dataObjectType)
	}
}

// ResolveDataObjectRedisKey resolves a full or short token to the canonical
// full-token Redis hash created during data-object initialization.
func ResolveDataObjectRedisKey(
	ctx context.Context,
	rdb *redis.Client,
	dataObjectType constants.DataObjectType,
	token string,
) (string, error) {
	if rdb == nil {
		return "", fmt.Errorf("redis client is not initialized")
	}
	classifiedType, err := ClassifyDataObjectToken(token)
	if err != nil {
		return "", err
	}
	if classifiedType != dataObjectType {
		return "", fmt.Errorf("token %q is %q, expected %q", token, classifiedType, dataObjectType)
	}

	aliasKey, err := DataObjectRedisAliasKey(dataObjectType, token)
	if err != nil {
		return "", err
	}
	canonicalKey, err := rdb.Get(ctx, aliasKey).Result()
	if errors.Is(err, redis.Nil) {
		switch dataObjectType {
		case constants.DataObjectTypeParameter:
			return "", fmt.Errorf("%w: %q", common.ErrParameterTokenNotFound, token)
		case constants.DataObjectTypeMeasurement:
			return "", fmt.Errorf("%w: %q", common.ErrMeasurementTokenNotFound, token)
		}
	}
	if err != nil {
		return "", fmt.Errorf("resolve redis data-object alias %q: %w", token, err)
	}
	if canonicalKey == "" {
		return "", fmt.Errorf("redis data-object alias %q points to an empty key", token)
	}
	keyType, err := rdb.Type(ctx, canonicalKey).Result()
	if err != nil {
		return "", fmt.Errorf("query canonical redis key type for %q: %w", token, err)
	}
	if keyType != "hash" {
		return "", fmt.Errorf(
			"redis data-object alias %q points to key %q with type %q, expected hash",
			token,
			canonicalKey,
			keyType,
		)
	}
	return canonicalKey, nil
}