wikimedia/mediawiki-extensions-Wikibase

import {
    DataValue,
    Snak,
    Statement,
    StatementMap,
} from '@wmde/wikibase-datamodel-types';
import StatementMutationStrategy from '@/change-op/statement-mutation/strategies/StatementMutationStrategy';
import EntityId from '@/datamodel/EntityId';
import { PathToStatement } from '@/store/statements/PathToStatement';
import { PathToSnak } from '@/store/statements/PathToSnak';
import { PathToStatementGroup } from '@/store/statements/PathToStatementGroup';
import StatementMutationError from '@/change-op/statement-mutation/StatementMutationError';

export default class UpdateMutationStrategy implements StatementMutationStrategy {
    public apply<T extends Record<EntityId, StatementMap>>(
        targetValue: DataValue,
        path: PathToStatement & PathToSnak & PathToStatementGroup,
        state: T,
    ): T {
        const statementGroup = path.resolveStatementGroup( state );
        const oldStatement = path.resolveStatement( state );
        if ( statementGroup === null ) {
            throw new Error( StatementMutationError.NO_STATEMENT_GROUP_FOUND );
        }
        if ( oldStatement === null ) {
            throw new Error( StatementMutationError.NO_SNAK_FOUND );
        }

        const oldSnak = oldStatement.mainsnak;
        if ( oldSnak.datavalue !== undefined && targetValue.type !== oldSnak.datavalue.type ) {
            throw new Error( StatementMutationError.INCONSISTENT_PAYLOAD_TYPE );
        }

        oldStatement.rank = 'normal';

        const newStatement = this.buildNewPreferredStatement(
            oldSnak,
            targetValue,
        );

        statementGroup.push( newStatement );

        return state;
    }

    private buildNewPreferredStatement( oldSnak: Snak, newDataValue: DataValue ): Statement {
        return {
            rank: 'preferred',
            type: 'statement',
            mainsnak: {
                snaktype: 'value',
                property: oldSnak.property,
                datatype: oldSnak.datatype,
                datavalue: newDataValue,
            },
        };
    }

}