Initial

Validator.ts

@@ -0,0 +1,97 @@
+export type Args = {[_: string]: any};
+
+export interface Validator {
+  type: string;
+  check: (value: any) => Promise<Args|undefined>|Args|undefined;
+  message: (value: any, args?: Args) => Promise<string|undefined>|string|undefined;
+}
+
+export interface ValidationError {
+  type: string;
+  param?: string[];
+  message?: string|null;
+  args?: Args;
+}
+
+export type Validatable = Schema|Validator|Validator[];
+
+export const ArraySymbol: unique symbol = Symbol("ArraySymbol");
+export type Schema = {[key: string]: Validatable}|{[ArraySymbol]: Validatable};
+
+export async function validate(value: any, validators: Validatable): Promise<ValidationError[]|undefined> {
+  if (instanceofValidatorArray(validators) || instanceofValidator(validators)) {
+    return validateValue(value, validators);
+  } else {
+    return validateSchema(value, validators);
+  }
+}
+
+function instanceofValidator(value: any): value is Validator {
+  return value &&
+    value.hasOwnProperty("type") && typeof value.type === "string" &&
+    value.hasOwnProperty("check") && typeof value.check === "function" &&
+    value.hasOwnProperty("message") && typeof value.message === "function";
+}
+
+function instanceofValidatorArray(value: any): value is Validator[] {
+  return Array.isArray(value) && value.every(x => instanceofValidator(x));
+}
+
+async function validateValue(value: any, validators: Validator|Validator[]): Promise<ValidationError[]> {
+  if (!Array.isArray(validators)) {
+    validators = [validators];
+  }
+  const result: ValidationError[] = [];
+  for (const validator of validators) {
+    const args = await validator.check(value);
+    if (args !== undefined) {
+      const message = await validator.message(value, args);
+      result.push({
+        type: validator.type,
+        args,
+        message
+      });
+    }
+  }
+  return result;
+}
+
+async function validateSchema(value: any, validators: Schema): Promise<ValidationError[]> {
+  if (validators.hasOwnProperty(ArraySymbol)) {
+    const v = validators as {[ArraySymbol]: Validatable};
+    if (Array.isArray(value)) {
+      const arr = await Promise.all(value.map(val => validate(val, v[ArraySymbol])));
+      const errors = arr.flatMap((val, idx) => (val ?? []).map(error => ({
+        ...error,
+        param: [`[${idx}]`, ...(error.param || [])]
+      })));
+      return errors;
+    } else {
+      return [{
+        type: "array",
+        param: ["[]"],
+        message: "Array expected!",
+        args: {}
+      }];
+    }
+  }
+  const v = validators as {[key: string]: Validatable};
+  const valErrors: ValidationError[] = [];
+  for (const prop in validators) {
+    if (!validators.hasOwnProperty(prop)) {
+      continue;
+    }
+    if (value.hasOwnProperty(prop)) {
+      const errors = await validate(value[prop], v[prop]);
+      valErrors.push(...(errors ?? []));
+    } else {
+      valErrors.push({
+        type: "property",
+        param: [prop],
+        message: `Property '${prop}' expected but not found!`,
+        args: {property: prop}
+      });
+    }
+  }
+  return valErrors;
+}