@graphql-tools/utils/esm/prune.js

import { getNamedType, isObjectType, isInterfaceType, isUnionType, isInputObjectType, isSpecifiedScalarType, isScalarType, } from 'graphql';
import { mapSchema } from './mapSchema.js';
import { MapperKind } from './Interfaces.js';
import { getRootTypes } from './rootTypes.js';
import { getImplementingTypes } from './get-implementing-types.js';
/**
 * Prunes the provided schema, removing unused and empty types
 * @param schema The schema to prune
 * @param options Additional options for removing unused types from the schema
 */
export function pruneSchema(schema, options = {}) {
    const { skipEmptyCompositeTypePruning, skipEmptyUnionPruning, skipPruning, skipUnimplementedInterfacesPruning, skipUnusedTypesPruning, } = options;
    let prunedTypes = []; // Pruned types during mapping
    let prunedSchema = schema;
    do {
        let visited = visitSchema(prunedSchema);
        // Custom pruning  was defined, so we need to pre-emptively revisit the schema accounting for this
        if (skipPruning) {
            const revisit = [];
            for (const typeName in prunedSchema.getTypeMap()) {
                if (typeName.startsWith('__')) {
                    continue;
                }
                const type = prunedSchema.getType(typeName);
                // if we want to skip pruning for this type, add it to the list of types to revisit
                if (type && skipPruning(type)) {
                    revisit.push(typeName);
                }
            }
            visited = visitQueue(revisit, prunedSchema, visited); // visit again
        }
        prunedTypes = [];
        prunedSchema = mapSchema(prunedSchema, {
            [MapperKind.TYPE]: type => {
                if (!visited.has(type.name) && !isSpecifiedScalarType(type)) {
                    if (isUnionType(type) ||
                        isInputObjectType(type) ||
                        isInterfaceType(type) ||
                        isObjectType(type) ||
                        isScalarType(type)) {
                        // skipUnusedTypesPruning: skip pruning unused types
                        if (skipUnusedTypesPruning) {
                            return type;
                        }
                        // skipEmptyUnionPruning: skip pruning empty unions
                        if (isUnionType(type) && skipEmptyUnionPruning && !Object.keys(type.getTypes()).length) {
                            return type;
                        }
                        if (isInputObjectType(type) || isInterfaceType(type) || isObjectType(type)) {
                            // skipEmptyCompositeTypePruning: skip pruning object types or interfaces with no fields
                            if (skipEmptyCompositeTypePruning && !Object.keys(type.getFields()).length) {
                                return type;
                            }
                        }
                        // skipUnimplementedInterfacesPruning: skip pruning interfaces that are not implemented by any other types
                        if (isInterfaceType(type) && skipUnimplementedInterfacesPruning) {
                            return type;
                        }
                    }
                    prunedTypes.push(type.name);
                    visited.delete(type.name);
                    return null;
                }
                return type;
            },
        });
    } while (prunedTypes.length); // Might have empty types and need to prune again
    return prunedSchema;
}
function visitSchema(schema) {
    const queue = []; // queue of nodes to visit
    // Grab the root types and start there
    for (const type of getRootTypes(schema)) {
        queue.push(type.name);
    }
    return visitQueue(queue, schema);
}
function visitQueue(queue, schema, visited = new Set()) {
    // Interfaces encountered that are field return types need to be revisited to add their implementations
    const revisit = new Map();
    // Navigate all types starting with pre-queued types (root types)
    while (queue.length) {
        const typeName = queue.pop();
        // Skip types we already visited unless it is an interface type that needs revisiting
        if (visited.has(typeName) && revisit[typeName] !== true) {
            continue;
        }
        const type = schema.getType(typeName);
        if (type) {
            // Get types for union
            if (isUnionType(type)) {
                queue.push(...type.getTypes().map(type => type.name));
            }
            // If it is an interface and it is a returned type, grab all implementations so we can use proper __typename in fragments
            if (isInterfaceType(type) && revisit[typeName] === true) {
                queue.push(...getImplementingTypes(type.name, schema));
                // No need to revisit this interface again
                revisit[typeName] = false;
            }
            // Visit interfaces this type is implementing if they haven't been visited yet
            if ('getInterfaces' in type) {
                // Only pushes to queue to visit but not return types
                queue.push(...type.getInterfaces().map(iface => iface.name));
            }
            // If the type has files visit those field types
            if ('getFields' in type) {
                const fields = type.getFields();
                const entries = Object.entries(fields);
                if (!entries.length) {
                    continue;
                }
                for (const [, field] of entries) {
                    if (isObjectType(type)) {
                        // Visit arg types
                        queue.push(...field.args.map(arg => getNamedType(arg.type).name));
                    }
                    const namedType = getNamedType(field.type);
                    queue.push(namedType.name);
                    // Interfaces returned on fields need to be revisited to add their implementations
                    if (isInterfaceType(namedType) && !(namedType.name in revisit)) {
                        revisit[namedType.name] = true;
                    }
                }
            }
            visited.add(typeName); // Mark as visited (and therefore it is used and should be kept)
        }
    }
    return visited;
}