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import { stringLengthInBytes } from "../util/bytes.ts";import { onlyHasChars } from "./characters.ts";
//================================================================================
// Similar to JSON schema, these functions help check if// data is in the expected format.// A "checker" function returns null on success, or a string on error.
type Ob = { [k: string]: any };
export type Checker = (x: any) => null | string; // returns err, which can be nullexport type CheckerSchema = {  [k: string]: Checker;};
//================================================================================
export function isPlainObject(obj: any): obj is Ob {  if (Object.prototype.toString.call(obj) !== "[object Object]") {    return false;  }  // reject class instances  if (("" + obj.constructor).startsWith("class")) return false;  return true;}export function checkIsPlainObject(x: any): null | string {  return isPlainObject(x) ? null : "expected plain object but got " + x;}
//================================================================================
export function checkLiteral(val: any): Checker {  return (x: any): null | string => {    if (x !== val) return `expected literal value ${JSON.stringify(val)}`;    return null;  };}
//================================================================================
export interface CheckStringOpts {  optional?: boolean; // default false  minLen?: number; // minimum allowable length (inclusive) (counting utf-8 bytes)  maxLen?: number; // maximum allowable length (inclusive) (counting utf-8 bytes)  len?: number; // same as setting minLen and maxLen to the same number  allowedChars?: string; // all the characters that our checked string is allowed to have}export function checkString(opts: CheckStringOpts = {}): Checker {  return ((x: any): null | string => {    if (opts.optional !== true && x === undefined) return "required";    if (opts.optional === true && x === undefined) return null; // skip the rest of the checks if it's undefined
    //let len = x.length;  // TODO: string length or byte length?    let len = stringLengthInBytes(x);    if (typeof x !== "string") {      return "expected a string but got " + JSON.stringify(x);    }    if (opts.minLen !== undefined && len < opts.minLen) {      return `string shorter than min length of ${opts.minLen} chars`;    }    if (opts.maxLen !== undefined && len > opts.maxLen) {      return `string shorter than max length of ${opts.maxLen} chars`;    }    if (opts.len !== undefined && len !== opts.len) {      return `string does not have required length of ${opts.len} chars: ${x}`;    }    if (      opts.allowedChars !== undefined &&      !onlyHasChars(x, opts.allowedChars)    ) {      return "contains disallowed characters";    }    return null;  });}
//================================================================================
export interface CheckIntOpts {  optional?: boolean; // default false  nullable?: boolean; // default false  min?: number; // inclusive  max?: number; // inclusive}export function checkInt(opts: CheckIntOpts = {}): Checker {  return ((x: any): null | string => {    if (opts.optional !== true && x === undefined) return "required";    if (opts.optional === true && x === undefined) return null; // skip the rest of the checks if it's undefined    if (opts.nullable !== true && x === null) return "not nullable";    if (opts.nullable === true && x === null) return null; // skip the rest of the checks if it's null
    if (typeof x !== "number") {      return "expected a number but got " + JSON.stringify(x);    }    if (isNaN(x)) return "is NaN";    if (!isFinite(x)) return "is Infinity";    if (x !== Math.round(x)) return "expected an integer";    if (opts.min !== undefined && x < opts.min) {      return `integer too small (must be >= ${opts.min})`;    }    if (opts.max !== undefined && x > opts.max) {      return `integer too large (must be <= ${opts.max})`;    }    return null;  });}
//================================================================================
export interface CheckObjOpts {  allowLiteralUndefined?: boolean; // default false.  allow values in the object to be explicitly set to undefined (rather than omitted)?  allowExtraKeys?: boolean; // default false.  allow keys not set in objSchema?  to use this, you must also define objSchema  objSchema?: CheckerSchema; // an object of validators}export function checkObj(opts: CheckObjOpts = {}): Checker {  // set defaults  opts.allowLiteralUndefined = opts.allowLiteralUndefined ?? false;  opts.allowExtraKeys = opts.allowExtraKeys ?? false;  return (x: any): null | string => {    if (!isPlainObject(x)) return "expected an object";    if (opts.allowLiteralUndefined === false) {      // don't allow any keys to be literally undefined, e.g. exiting but set to undefined.      // when this is false, optional keys have to be omitted instead of set to undefined.      for (let [k, v] of Object.entries(x)) {        if (v === undefined) {          return `${k} is explicitly set to undefined but should be missing instead`;        }      }    }    if (opts.objSchema !== undefined) {      // look for extra keys      if (opts.allowExtraKeys === false) {        let objKeys = Object.keys(x);        let schemaKeys = Object.keys(opts.objSchema);        let extraObjKeys = objKeys.filter((k) => schemaKeys.indexOf(k) === -1);        if (extraObjKeys.length > 0) {          return `object has extra keys not in the schema: ${            extraObjKeys.join(", ")          }`;        }      }      // check the individual schemas of each key      for (let [key, validator] of Object.entries(opts.objSchema)) {        let err = validator(x[key]);        if (err !== null) return `${key}: ${err}`;      }    }    return null;  };}