flagsmith-nodejs/flagsmith-engine/segments/evaluators.ts

Flagsmith lets you manage features flags and remote config across web, mobile and server side applications. Deliver true Continuous Integration. Get builds out faster. Control who has access to new features.

import { EnvironmentModel } from '../environments/models.js';
import { IdentityModel } from '../identities/models.js';
import { TraitModel } from '../identities/traits/models.js';
import { getHashedPercentateForObjIds } from '../utils/hashing/index.js';
import { PERCENTAGE_SPLIT, IS_SET, IS_NOT_SET } from './constants.js';
import { SegmentConditionModel, SegmentModel, SegmentRuleModel } from './models.js';

export function getIdentitySegments(
    environment: EnvironmentModel,
    identity: IdentityModel,
    overrideTraits?: TraitModel[]
): SegmentModel[] {
    return environment.project.segments.filter(segment =>
        evaluateIdentityInSegment(identity, segment, overrideTraits)
    );
}

export function evaluateIdentityInSegment(
    identity: IdentityModel,
    segment: SegmentModel,
    overrideTraits?: TraitModel[]
): boolean {
    return (
        segment.rules.length > 0 &&
        segment.rules.filter(rule =>
            traitsMatchSegmentRule(
                overrideTraits || identity.identityTraits,
                rule,
                segment.id,
                identity.djangoID || identity.compositeKey
            )
        ).length === segment.rules.length
    );
}

function traitsMatchSegmentRule(
    identityTraits: TraitModel[],
    rule: SegmentRuleModel,
    segmentId: number | string,
    identityId: number | string
): boolean {
    const matchesConditions =
        rule.conditions.length > 0
            ? rule.matchingFunction()(
                  rule.conditions.map(condition =>
                      traitsMatchSegmentCondition(identityTraits, condition, segmentId, identityId)
                  )
              )
            : true;
    return (
        matchesConditions &&
        rule.rules.filter(rule =>
            traitsMatchSegmentRule(identityTraits, rule, segmentId, identityId)
        ).length === rule.rules.length
    );
}

export function traitsMatchSegmentCondition(
    identityTraits: TraitModel[],
    condition: SegmentConditionModel,
    segmentId: number | string,
    identityId: number | string
): boolean {
    if (condition.operator == PERCENTAGE_SPLIT) {
        var hashedPercentage = getHashedPercentateForObjIds([segmentId, identityId]);
        return hashedPercentage <= parseFloat(String(condition.value));
    }
    const traits = identityTraits.filter(t => t.traitKey === condition.property_);
    const trait = traits.length > 0 ? traits[0] : undefined;
    if (condition.operator === IS_SET) {
        return !!trait;
    } else if (condition.operator === IS_NOT_SET) {
        return trait == undefined;
    }
    return trait ? condition.matchesTraitValue(trait.traitValue) : false;
}