@alexop/openapi-zod-client/src/openApiToZod.ts

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import type { ReferenceObject, SchemaObject } from "openapi3-ts";
import { match } from "ts-pattern";

import type { CodeMetaData, ConversionTypeContext } from "./CodeMeta";
import { CodeMeta } from "./CodeMeta";
import { isReferenceObject } from "./isReferenceObject";
import type { TemplateContext } from "./template-context";
import { escapeControlCharacters, isPrimitiveType, wrapWithQuotesIfNeeded } from "./utils";

type ConversionArgs = {
    schema: SchemaObject | ReferenceObject;
    ctx?: ConversionTypeContext | undefined;
    meta?: CodeMetaData | undefined;
    options?: TemplateContext["options"] | undefined;
};

/**
 * @see https://github.com/OAI/OpenAPI-Specification/blob/main/versions/3.0.3.md#schemaObject
 * @see https://github.com/colinhacks/zod
 */
// eslint-disable-next-line sonarjs/cognitive-complexity
export function getZodSchema({ schema, ctx, meta: inheritedMeta, options }: ConversionArgs): CodeMeta {
    if (!schema) {
        throw new Error("Schema is required");
    }

    const code = new CodeMeta(schema, ctx, inheritedMeta);
    const meta = {
        parent: code.inherit(inheritedMeta?.parent),
        referencedBy: [...code.meta.referencedBy],
    };

    const refsPath = code.meta.referencedBy
        .slice(0, -1)
        .map((prev) => (ctx ? ctx.resolver.resolveRef(prev.ref!).normalized : prev.ref!));

    if (isReferenceObject(schema)) {
        if (!ctx) throw new Error("Context is required");

        const schemaName = ctx.resolver.resolveRef(schema.$ref)?.normalized;

        // circular(=recursive) reference
        if (refsPath.length > 1 && refsPath.includes(schemaName)) {
            return code.assign(ctx.zodSchemaByName[code.ref!]!);
        }

        let result = ctx.zodSchemaByName[schema.$ref];
        if (!result) {
            const actualSchema = ctx.resolver.getSchemaByRef(schema.$ref);
            if (!actualSchema) {
                throw new Error(`Schema ${schema.$ref} not found`);
            }

            result = getZodSchema({ schema: actualSchema, ctx, meta, options }).toString();
        }

        if (ctx.zodSchemaByName[schemaName]) {
            return code;
        }

        ctx.zodSchemaByName[schemaName] = result;

        return code;
    }

    if (Array.isArray(schema.type)) {
        if (schema.type.length === 1) {
            return getZodSchema({ schema: { ...schema, type: schema.type[0]! }, ctx, meta, options });
        }

        return code.assign(
            `z.union([${schema.type
                .map((prop) => getZodSchema({ schema: { ...schema, type: prop }, ctx, meta, options }))
                .join(", ")}])`
        );
    }

    if (schema.type === "null") {
        return code.assign("z.null()");
    }

    if (schema.oneOf) {
        if (schema.oneOf.length === 1) {
            const type = getZodSchema({ schema: schema.oneOf[0]!, ctx, meta, options });
            return code.assign(type.toString());
        }

        if (schema.discriminator) {
            const propertyName = schema.discriminator.propertyName;

            return code.assign(`
                z.discriminatedUnion("${propertyName}", [${schema.oneOf
                .map((prop) => getZodSchema({ schema: prop, ctx, meta, options }))
                .join(", ")}])
            `);
        }

        return code.assign(
            `z.union([${schema.oneOf.map((prop) => getZodSchema({ schema: prop, ctx, meta, options })).join(", ")}])`
        );
    }

    // anyOf = oneOf but with 1 or more = `T extends oneOf ? T | T[] : never`
    if (schema.anyOf) {
        if (schema.anyOf.length === 1) {
            const type = getZodSchema({ schema: schema.anyOf[0]!, ctx, meta, options });
            return code.assign(type.toString());
        }

        const types = schema.anyOf
            .map((prop) => getZodSchema({ schema: prop, ctx, meta, options }))
            .map((type) => {
                let isObject = true;

                if ("type" in type.schema) {
                    if (Array.isArray(type.schema.type)) {
                        isObject = false;
                    } else {
                        const schemaType = type.schema.type.toLowerCase() as NonNullable<typeof schema.type>;
                        isObject = !isPrimitiveType(schemaType);
                    }
                }

                return type.toString();
            })
            .join(", ");

        return code.assign(`z.union([${types}])`);
    }

    if (schema.allOf) {
        if (schema.allOf.length === 1) {
            const type = getZodSchema({ schema: schema.allOf[0]!, ctx, meta, options });
            return code.assign(type.toString());
        }

        const types = schema.allOf.map((prop) => getZodSchema({ schema: prop, ctx, meta, options }));
        const first = types.at(0)!;
        const rest = types
            .slice(1)
            .map((type) => `and(${type.toString()})`)
            .join(".");

        return code.assign(`${first.toString()}.${rest}`);
    }

    const schemaType = schema.type ? (schema.type.toLowerCase() as NonNullable<typeof schema.type>) : undefined;
    if (schemaType && isPrimitiveType(schemaType)) {
        if (schema.enum) {
            if (schemaType === "string") {
                if (schema.enum.length === 1) {
                    const value = schema.enum[0];
                    const valueString = value === null ? "null" : `"${value}"`;
                    return code.assign(`z.literal(${valueString})`);
                }

                // eslint-disable-next-line sonarjs/no-nested-template-literals
                return code.assign(`z.enum([${schema.enum.map((value) => `"${value}"`).join(", ")}])`);
            }

            if (schema.enum.some((e) => typeof e === "string")) {
                return code.assign("z.never()");
            }

            if (schema.enum.length === 1) {
                const value = schema.enum[0];
                return code.assign(`z.literal(${value === null ? "null" : value})`);
            }

            return code.assign(
                // eslint-disable-next-line sonarjs/no-nested-template-literals
                `z.union([${schema.enum.map((value) => `z.literal(${value === null ? "null" : value})`).join(", ")}])`
            );
        }

        return code.assign(
            match(schemaType)
                .with("integer", () => "z.number()")
                .with("string", () =>
                    match(schema.format)
                        .with("binary", () => "z.instanceof(File)")
                        .otherwise(() => "z.string()")
                )
                .otherwise((type) => `z.${type}()`)
        );
    }

    const readonly = options?.allReadonly ? ".readonly()" : "";

    if (schemaType === "array") {
        if (schema.items) {
            return code.assign(
                `z.array(${getZodSchema({ schema: schema.items, ctx, meta, options }).toString()})${readonly}`
            );
        }

        return code.assign(`z.array(z.any())${readonly}`);
    }

    if (schemaType === "object" || schema.properties || schema.additionalProperties) {
        // additional properties are allowed by default unless explicitly opting out
        const additionalProps = schema.additionalProperties === false ? "" : ".passthrough()";

        if (typeof schema.additionalProperties === "object" && Object.keys(schema.additionalProperties).length > 0) {
            return code.assign(
                `z.record(${(
                    getZodSchema({ schema: schema.additionalProperties, ctx, meta, options }) +
                    getZodChain({
                        schema: schema.additionalProperties as SchemaObject,
                        meta: { ...meta, isRequired: true },
                        options,
                    })
                ).toString()})`
            );
        }

        const hasRequiredArray = schema.required && schema.required.length > 0;
        const isPartial = options?.withImplicitRequiredProps ? false : !schema.required?.length;
        let properties = "{}";

        if (schema.properties) {
            const propsMap = Object.entries(schema.properties).map(([prop, propSchema]) => {
                const propMetadata = {
                    ...meta,
                    isRequired: isPartial
                        ? true
                        : hasRequiredArray
                        ? schema.required?.includes(prop)
                        : options?.withImplicitRequiredProps,
                    name: prop,
                } as CodeMetaData;

                let propActualSchema = propSchema;

                if (isReferenceObject(propSchema) && ctx?.resolver) {
                    propActualSchema = ctx.resolver.getSchemaByRef(propSchema.$ref);
                    if (!propActualSchema) {
                        throw new Error(`Schema ${propSchema.$ref} not found`);
                    }
                }

                const propCode =
                    getZodSchema({ schema: propSchema, ctx, meta: propMetadata, options }) +
                    getZodChain({ schema: propActualSchema as SchemaObject, meta: propMetadata, options });

                return [prop, propCode.toString()];
            });

            properties =
                "{ " +
                propsMap.map(([prop, propSchema]) => `${wrapWithQuotesIfNeeded(prop!)}: ${propSchema}`).join(", ") +
                " }";
        }

        const partial = isPartial ? ".partial()" : "";

        return code.assign(`z.object(${properties})${partial}${additionalProps}${readonly}`);
    }

    if (!schemaType) return code.assign("z.unknown()");

    // eslint-disable-next-line @typescript-eslint/restrict-template-expressions
    throw new Error(`Unsupported schema type: ${schemaType}`);
}

type ZodChainArgs = { schema: SchemaObject; meta?: CodeMetaData; options?: TemplateContext["options"] };

export const getZodChain = ({ schema, meta, options }: ZodChainArgs) => {
    const chains: string[] = [];

    match(schema.type)
        .with("string", () => chains.push(getZodChainableStringValidations(schema)))
        .with("number", "integer", () => chains.push(getZodChainableNumberValidations(schema)))
        .with("array", () => chains.push(getZodChainableArrayValidations(schema)))
        .otherwise(() => void 0);

    if (typeof schema.description === "string" && schema.description !== "" && options?.withDescription) {
        chains.push(`describe("${schema.description}")`);
    }

    const output = chains
        .concat(
            getZodChainablePresence(schema, meta),
            options?.withDefaultValues !== false ? getZodChainableDefault(schema) : []
        )
        .filter(Boolean)
        .join(".");
    return output ? `.${output}` : "";
};

const getZodChainablePresence = (schema: SchemaObject, meta?: CodeMetaData) => {
    if (schema.nullable && !meta?.isRequired) {
        return "nullish()";
    }

    if (schema.nullable) {
        return "nullable()";
    }

    if (!meta?.isRequired) {
        return "optional()";
    }

    return "";
};

// TODO OA prefixItems -> z.tuple
const unwrapQuotesIfNeeded = (value: string | number) => {
    if (typeof value === "string" && value.startsWith('"') && value.endsWith('"')) {
        return value.slice(1, -1);
    }

    return value;
};

const getZodChainableDefault = (schema: SchemaObject) => {
    if (schema.default) {
        const value = match(schema.type)
            .with("number", "integer", () => unwrapQuotesIfNeeded(schema.default))
            .otherwise(() => JSON.stringify(schema.default));
        return `default(${value})`;
    }

    return "";
};

const formatPatternIfNeeded = (pattern: string) => {
    if (pattern.startsWith("/") && pattern.endsWith("/")) {
        pattern = pattern.slice(1, -1);
    }

    pattern = escapeControlCharacters(pattern);

    return `/${pattern}/`;
};

const getZodChainableStringValidations = (schema: SchemaObject) => {
    const validations: string[] = [];

    if (!schema.enum) {
        if (schema.minLength !== undefined) {
            validations.push(`min(${schema.minLength})`);
        }

        if (schema.maxLength !== undefined) {
            validations.push(`max(${schema.maxLength})`);
        }
    }

    if (schema.pattern) {
        validations.push(`regex(${formatPatternIfNeeded(schema.pattern)})`);
    }

    if (schema.format) {
        const chain = match(schema.format)
            .with("email", () => "email()")
            .with("hostname", () => "url()")
            .with("uri", () => "url()")
            .with("uuid", () => "uuid()")
            .with("date-time", () => "datetime({ offset: true })")
            .otherwise(() => "");

        if (chain) {
            validations.push(chain);
        }
    }

    return validations.join(".");
};

const getZodChainableNumberValidations = (schema: SchemaObject) => {
    const validations: string[] = [];

    // none of the chains are valid for enums
    if (schema.enum) {
        return "";
    }

    if (schema.type === "integer") {
        validations.push("int()");
    }

    if (schema.minimum !== undefined) {
        if (schema.exclusiveMinimum === true) {
            validations.push(`gt(${schema.minimum})`);
        } else {
            validations.push(`gte(${schema.minimum})`);
        }
    } else if (typeof schema.exclusiveMinimum === "number") {
        validations.push(`gt(${schema.exclusiveMinimum})`);
    }

    if (schema.maximum !== undefined) {
        if (schema.exclusiveMaximum === true) {
            validations.push(`lt(${schema.maximum})`);
        } else {
            validations.push(`lte(${schema.maximum})`);
        }
    } else if (typeof schema.exclusiveMaximum === "number") {
        validations.push(`lt(${schema.exclusiveMaximum})`);
    }

    if (schema.multipleOf) {
        validations.push(`multipleOf(${schema.multipleOf})`);
    }

    return validations.join(".");
};

const getZodChainableArrayValidations = (schema: SchemaObject) => {
    const validations: string[] = [];

    if (schema.minItems) {
        validations.push(`min(${schema.minItems})`);
    }

    if (schema.maxItems) {
        validations.push(`max(${schema.maxItems})`);
    }

    return validations.join(".");
};