Create proxy system for json schema validation

1 files changed, 413 insertions, 0 deletions

diff --git a/ext/bg/js/json-schema.js b/ext/bg/js/json-schema.js
new file mode 100644
index 00000000..b059d757
--- /dev/null
+++ b/ext/bg/js/json-schema.js
@@ -0,0 +1,413 @@
+/*
+ * Copyright (C) 2019  Alex Yatskov <alex@foosoft.net>
+ * Author: Alex Yatskov <alex@foosoft.net>
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+
+class JsonSchemaProxyHandler {
+    constructor(schema) {
+        this._schema = schema;
+    }
+
+    getPrototypeOf(target) {
+        return Object.getPrototypeOf(target);
+    }
+
+    setPrototypeOf() {
+        throw new Error('setPrototypeOf not supported');
+    }
+
+    isExtensible(target) {
+        return Object.isExtensible(target);
+    }
+
+    preventExtensions(target) {
+        Object.preventExtensions(target);
+        return true;
+    }
+
+    getOwnPropertyDescriptor(target, property) {
+        return Object.getOwnPropertyDescriptor(target, property);
+    }
+
+    defineProperty() {
+        throw new Error('defineProperty not supported');
+    }
+
+    has(target, property) {
+        return property in target;
+    }
+
+    get(target, property) {
+        if (typeof property === 'symbol') {
+            return target[property];
+        }
+
+        if (Array.isArray(target)) {
+            if (typeof property === 'string' && /^\d+$/.test(property)) {
+                property = parseInt(property, 10);
+            } else if (typeof property === 'string') {
+                return target[property];
+            }
+        }
+
+        const propertySchema = JsonSchemaProxyHandler.getPropertySchema(this._schema, property);
+        if (propertySchema === null) {
+            return;
+        }
+
+        const value = target[property];
+        return value !== null && typeof value === 'object' ? JsonSchema.createProxy(value, propertySchema) : value;
+    }
+
+    set(target, property, value) {
+        if (Array.isArray(target)) {
+            if (typeof property === 'string' && /^\d+$/.test(property)) {
+                property = parseInt(property, 10);
+                if (property > target.length) {
+                    throw new Error('Array index out of range');
+                }
+            } else if (typeof property === 'string') {
+                target[property] = value;
+                return true;
+            }
+        }
+
+        const propertySchema = JsonSchemaProxyHandler.getPropertySchema(this._schema, property);
+        if (propertySchema === null) {
+            throw new Error(`Property ${property} not supported`);
+        }
+
+        value = JsonSchema.isolate(value);
+
+        const error = JsonSchemaProxyHandler.validate(value, propertySchema);
+        if (error !== null) {
+            throw new Error(`Invalid value: ${error}`);
+        }
+
+        target[property] = value;
+        return true;
+    }
+
+    deleteProperty(target, property) {
+        const required = this._schema.required;
+        if (Array.isArray(required) && required.includes(property)) {
+            throw new Error(`${property} cannot be deleted`);
+        }
+        return Reflect.deleteProperty(target, property);
+    }
+
+    ownKeys(target) {
+        return Reflect.ownKeys(target);
+    }
+
+    apply() {
+        throw new Error('apply not supported');
+    }
+
+    construct() {
+        throw new Error('construct not supported');
+    }
+
+    static getPropertySchema(schema, property) {
+        const type = schema.type;
+        if (Array.isArray(type)) {
+            throw new Error(`Ambiguous property type for ${property}`);
+        }
+        switch (type) {
+            case 'object':
+            {
+                const properties = schema.properties;
+                if (properties !== null && typeof properties === 'object' && !Array.isArray(properties)) {
+                    if (Object.prototype.hasOwnProperty.call(properties, property)) {
+                        return properties[property];
+                    }
+                }
+
+                const additionalProperties = schema.additionalProperties;
+                return (additionalProperties !== null && typeof additionalProperties === 'object' && !Array.isArray(additionalProperties)) ? additionalProperties : null;
+            }
+            case 'array':
+            {
+                const items = schema.items;
+                return (items !== null && typeof items === 'object' && !Array.isArray(items)) ? items : null;
+            }
+            default:
+                return null;
+        }
+    }
+
+    static validate(value, schema) {
+        const type = JsonSchemaProxyHandler.getValueType(value);
+        const schemaType = schema.type;
+        if (!JsonSchemaProxyHandler.isValueTypeAny(value, type, schemaType)) {
+            return `Value type ${type} does not match schema type ${schemaType}`;
+        }
+
+        const schemaEnum = schema.enum;
+        if (Array.isArray(schemaEnum) && !JsonSchemaProxyHandler.valuesAreEqualAny(value, schemaEnum)) {
+            return 'Invalid enum value';
+        }
+
+        switch (type) {
+            case 'number':
+                return JsonSchemaProxyHandler.validateNumber(value, schema);
+            case 'string':
+                return JsonSchemaProxyHandler.validateString(value, schema);
+            case 'array':
+                return JsonSchemaProxyHandler.validateArray(value, schema);
+            case 'object':
+                return JsonSchemaProxyHandler.validateObject(value, schema);
+            default:
+                return null;
+        }
+    }
+
+    static validateNumber(value, schema) {
+        const multipleOf = schema.multipleOf;
+        if (typeof multipleOf === 'number' && Math.floor(value / multipleOf) * multipleOf !== value) {
+            return `Number is not a multiple of ${multipleOf}`;
+        }
+
+        const minimum = schema.minimum;
+        if (typeof minimum === 'number' && value < minimum) {
+            return `Number is less than ${minimum}`;
+        }
+
+        const exclusiveMinimum = schema.exclusiveMinimum;
+        if (typeof exclusiveMinimum === 'number' && value <= exclusiveMinimum) {
+            return `Number is less than or equal to ${exclusiveMinimum}`;
+        }
+
+        const maximum = schema.maximum;
+        if (typeof maximum === 'number' && value > maximum) {
+            return `Number is greater than ${maximum}`;
+        }
+
+        const exclusiveMaximum = schema.exclusiveMaximum;
+        if (typeof exclusiveMaximum === 'number' && value >= exclusiveMaximum) {
+            return `Number is greater than or equal to ${exclusiveMaximum}`;
+        }
+
+        return null;
+    }
+
+    static validateString(value, schema) {
+        const minLength = schema.minLength;
+        if (typeof minLength === 'number' && value.length < minLength) {
+            return 'String length too short';
+        }
+
+        const maxLength = schema.minLength;
+        if (typeof maxLength === 'number' && value.length > maxLength) {
+            return 'String length too long';
+        }
+
+        return null;
+    }
+
+    static validateArray(value, schema) {
+        const minItems = schema.minItems;
+        if (typeof minItems === 'number' && value.length < minItems) {
+            return 'Array length too short';
+        }
+
+        const maxItems = schema.maxItems;
+        if (typeof maxItems === 'number' && value.length > maxItems) {
+            return 'Array length too long';
+        }
+
+        return null;
+    }
+
+    static validateObject(value, schema) {
+        const properties = new Set(Object.getOwnPropertyNames(value));
+
+        const required = schema.required;
+        if (Array.isArray(required)) {
+            for (const property of required) {
+                if (!properties.has(property)) {
+                    return `Missing property ${property}`;
+                }
+            }
+        }
+
+        const minProperties = schema.minProperties;
+        if (typeof minProperties === 'number' && properties.length < minProperties) {
+            return 'Not enough object properties';
+        }
+
+        const maxProperties = schema.maxProperties;
+        if (typeof maxProperties === 'number' && properties.length > maxProperties) {
+            return 'Too many object properties';
+        }
+
+        for (const property of properties) {
+            const propertySchema = JsonSchemaProxyHandler.getPropertySchema(schema, property);
+            if (propertySchema === null) {
+                return `No schema found for ${property}`;
+            }
+            const error = JsonSchemaProxyHandler.validate(value[property], propertySchema);
+            if (error !== null) {
+                return error;
+            }
+        }
+
+        return null;
+    }
+
+    static isValueTypeAny(value, type, schemaTypes) {
+        if (typeof schemaTypes === 'string') {
+            return JsonSchemaProxyHandler.isValueType(value, type, schemaTypes);
+        } else if (Array.isArray(schemaTypes)) {
+            for (const schemaType of schemaTypes) {
+                if (JsonSchemaProxyHandler.isValueType(value, type, schemaType)) {
+                    return true;
+                }
+            }
+            return false;
+        }
+        return true;
+    }
+
+    static isValueType(value, type, schemaType) {
+        return (
+            type === schemaType ||
+            (schemaType === 'integer' && Math.floor(value) === value)
+        );
+    }
+
+    static getValueType(value) {
+        const type = typeof value;
+        if (type === 'object') {
+            if (value === null) { return 'null'; }
+            if (Array.isArray(value)) { return 'array'; }
+        }
+        return type;
+    }
+
+    static valuesAreEqualAny(value1, valueList) {
+        for (const value2 of valueList) {
+            if (JsonSchemaProxyHandler.valuesAreEqual(value1, value2)) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    static valuesAreEqual(value1, value2) {
+        return value1 === value2;
+    }
+
+    static getDefaultTypeValue(type) {
+        if (typeof type === 'string') {
+            switch (type) {
+                case 'null':
+                    return null;
+                case 'boolean':
+                    return false;
+                case 'number':
+                case 'integer':
+                    return 0;
+                case 'string':
+                    return '';
+                case 'array':
+                    return [];
+                case 'object':
+                    return {};
+            }
+        }
+        return null;
+    }
+
+    static getValidValueOrDefault(schema, value) {
+        let type = JsonSchemaProxyHandler.getValueType(value);
+        const schemaType = schema.type;
+        if (!JsonSchemaProxyHandler.isValueTypeAny(value, type, schemaType)) {
+            let assignDefault = true;
+
+            const schemaDefault = schema.default;
+            if (typeof schemaDefault !== 'undefined') {
+                value = JsonSchema.isolate(schemaDefault);
+                type = JsonSchemaProxyHandler.getValueType(value);
+                assignDefault = !JsonSchemaProxyHandler.isValueTypeAny(value, type, schemaType);
+            }
+
+            if (assignDefault) {
+                value = JsonSchemaProxyHandler.getDefaultTypeValue(schemaType);
+                type = JsonSchemaProxyHandler.getValueType(value);
+            }
+        }
+
+        if (type === 'object') {
+            value = JsonSchemaProxyHandler.populateObjectDefaults(value, schema);
+        }
+
+        return value;
+    }
+
+    static populateObjectDefaults(value, schema) {
+        const properties = new Set(Object.getOwnPropertyNames(value));
+
+        const required = schema.required;
+        if (Array.isArray(required)) {
+            for (const property of required) {
+                properties.delete(property);
+
+                const propertySchema = JsonSchemaProxyHandler.getPropertySchema(schema, property);
+                if (propertySchema === null) { continue; }
+                value[property] = JsonSchemaProxyHandler.getValidValueOrDefault(propertySchema, value[property]);
+            }
+        }
+
+        for (const property of properties) {
+            const propertySchema = JsonSchemaProxyHandler.getPropertySchema(schema, property);
+            if (propertySchema === null) {
+                Reflect.deleteProperty(value, property);
+            } else {
+                value[property] = JsonSchemaProxyHandler.getValidValueOrDefault(propertySchema, value[property]);
+            }
+        }
+
+        return value;
+    }
+}
+
+class JsonSchema {
+    static createProxy(target, schema) {
+        return new Proxy(target, new JsonSchemaProxyHandler(schema));
+    }
+
+    static getValidValueOrDefault(schema, value) {
+        return JsonSchemaProxyHandler.getValidValueOrDefault(schema, value);
+    }
+
+    static isolate(value) {
+        if (value === null) { return null; }
+
+        switch (typeof value) {
+            case 'boolean':
+            case 'number':
+            case 'string':
+            case 'bigint':
+            case 'symbol':
+                return value;
+        }
+
+        const stringValue = JSON.stringify(value);
+        return typeof stringValue === 'string' ? JSON.parse(stringValue) : null;
+    }
+}