fileserver/old_backend/tools/apigen.ts

import {
	AST_NODE_TYPES,
	createProgram,
	parse
} from '@typescript-eslint/typescript-estree';
import * as fs from 'fs';
import * as path from 'path';
import * as a from '@typescript-eslint/types/dist/generated/ast-spec';
import { TypeNode } from '@typescript-eslint/types/dist/generated/ast-spec';
import { Writable } from 'stream';

class Err extends Error {
	constructor(o: object) {
		super();
		console.error(o);
	}
}

const program = createProgram('tsconfig.json');

class BetterWritable {
	constructor(private w: Writable) {}
	private indent = 0;

	write(data: string) {
		this.w.write('\t'.repeat(this.indent));
		this.w.write(data);
		this.w.write('\n');
	}
	writeInc(data: string) {
		this.write(data);
		this.indent++;
	}
	writeDec(data: string) {
		this.indent--;
		this.write(data);
	}
	writeDecInc(data: string) {
		this.indent--;
		this.write(data);
		this.indent++;
	}
}

interface Outputable {
	write(s: BetterWritable);
	writeJsonAs(ns: string, s: BetterWritable);
}

class CppProp {
	constructor(entry: string) {
		this.entry = entry;
	}
	entry: string;
}

// template <> inline dto::Requests::Auth::LoginRequest Json::Value::as<dto::Requests::Auth::LoginRequest>() const { return asFloat(); }

class CppClass implements Outputable {
	constructor(name: string) {
		this.name = name;
	}
	type = 'class' as const;
	name: string;
	sub: string[] = [];
	entries: CppProp[] = [];

	write(s: BetterWritable) {
		let name = `struct ${this.name}`;
		if (this.sub.length > 0)
			name += ' : public ' + this.sub.join(', public ');
		s.writeInc(`${name} {`);
		if (this.sub.length == 0) {
			s.write(`${this.name}() = default;`);
			s.writeInc(`explicit ${this.name}(const Json::Value& j) {`);
		} else {
			s.writeInc(`${this.name}() :`);
			this.sub.forEach((sub) => {
				s.write(`${sub}()`);
			});
			s.writeDec('{}');
			s.writeInc(`explicit ${this.name}(const Json::Value& j) :`);
			this.sub.forEach((sub) => {
				s.write(`${sub}(j)`);
			});
			s.writeDecInc('{');
		}
		this.entries.forEach((e) => {
			const [type, name] = e.entry.split(' ');
			const opt_match = /std::optional<([a-z:<>]+)>/.exec(type);
			if (opt_match !== null)
				s.write(
					`this->${name} = json_get_optional<${opt_match[1]}>(j, "${name}");`
				);
			else s.write(`this->${name} = j["${name}"].as<${type}>();`);
		});
		s.writeDec('}');
		this.entries.forEach((e) => s.write(`${e.entry};`));
		s.writeDec('};');
	}

	writeJsonAs(ns: string, s: BetterWritable) {
		s.write(
			`template <> inline ${ns}${this.name} Json::Value::as() const { return ${ns}${this.name}(*this); }`
		);
	}
}

class CppEnum implements Outputable {
	constructor(name: string) {
		this.name = name;
	}
	type = 'enum' as const;
	name: string;
	entries: CppProp[] = [];

	write(s: BetterWritable) {
		return;
		s.writeInc(`enum ${this.name} : int {`);
		this.entries.forEach((e, idx, arr) =>
			s.write(`${e.entry}${idx === arr.length - 1 ? '' : ','}`)
		);
		s.writeDec('};');
	}

	writeJsonAs(ns: string, s: BetterWritable) {
		return;
		s.write(
			`template <> inline ${ns}${this.name} Json::Value::as() const { return (${ns}${this.name})(asInt()); }`
		);
	}
}

class CppNamespace implements Outputable {
	constructor(name: string) {
		this.name = name;
	}
	type = 'ns' as const;
	name: string;
	body: (CppNamespace | CppClass | CppEnum)[] = [];

	write(s: BetterWritable) {
		s.writeInc(`namespace ${this.name} {`);
		this.body.forEach((b) => b.write(s));
		s.writeDec('}');
	}

	writeJsonAs(ns: string, s: BetterWritable) {
		ns += `${this.name}::`;
		this.body.forEach((b) => b.writeJsonAs(ns, s));
	}
}

function _getCppType(
	t: TypeNode
): null | string | ((opt: boolean, name: string) => string) {
	switch (t.type) {
		case AST_NODE_TYPES.TSStringKeyword:
			return 'std::string';
		case AST_NODE_TYPES.TSBooleanKeyword:
			return 'bool';
		case AST_NODE_TYPES.TSNumberKeyword:
			return 'int';
		case AST_NODE_TYPES.TSTypeReference:
			if (t.typeName.type != AST_NODE_TYPES.Identifier) throw new Err(t);
			return t.typeName.name;
		case AST_NODE_TYPES.TSLiteralType:
			return null;
		case AST_NODE_TYPES.TSUnionType:
			return _getCppType(t.types[0]);
		case AST_NODE_TYPES.TSArrayType:
			return `std::vector<${_getCppType(t.elementType)}>`;
		default:
			throw new Err(t);
	}
}

function getCppType(opt: boolean, name: string, t: TypeNode): null | string {
	let ret = _getCppType(t);
	if (typeof ret === 'function') return `${ret(opt, name)}`;
	if (typeof ret === 'string') {
		if (opt) ret = `std::optional<${ret}>`;
		return `${ret} ${name}`;
	} else return ret;
}

function handleClassProperty(
	prop: a.PropertyDefinitionComputedName | a.PropertyDefinitionNonComputedName
): CppProp | null {
	if (prop.key.type != AST_NODE_TYPES.Identifier) throw new Err(prop);
	if (!prop.typeAnnotation) throw new Err(prop);
	const type = getCppType(
		prop.optional && prop.optional,
		prop.key.name,
		prop.typeAnnotation.typeAnnotation
	);
	return type === null ? null : new CppProp(type);
}

function handleClass(
	dec: a.ClassDeclarationWithName | a.ClassDeclarationWithOptionalName
): CppClass {
	if (!dec.id) throw new Err(dec);
	const cls = new CppClass(dec.id.name);
	if (dec.superClass) {
		const subCls = dec.superClass;
		if (subCls.type == AST_NODE_TYPES.Identifier) cls.sub.push(subCls.name);
		else throw new Err(subCls);
	}
	dec.body.body.forEach((inner) => {
		if (inner.type == AST_NODE_TYPES.PropertyDefinition) {
			const prop = handleClassProperty(inner);
			if (prop) cls.entries.push(prop);
		} else if (
			inner.type == AST_NODE_TYPES.MethodDefinition &&
			inner.key.type == AST_NODE_TYPES.Identifier &&
			inner.key.name === 'constructor'
		)
			return;
		else throw new Err(inner);
	});
	return cls;
}

function handleEnum(dec: a.TSEnumDeclaration): CppEnum {
	const enm = new CppEnum(dec.id.name);
	dec.members.forEach((member) => {
		if (
			member.id.type == AST_NODE_TYPES.Identifier &&
			member.initializer.type == AST_NODE_TYPES.Literal
		) {
			enm.entries.push(
				new CppProp(`${member.id.name} = ${member.initializer.raw}`)
			);
		} else throw new Err(member);
	});
	return enm;
}

function handleNamedDeclaration(
	dec: a.ExportNamedDeclaration
): CppClass | CppEnum | undefined {
	if (!dec.declaration) throw new Err(dec);
	else if (dec.declaration.type == AST_NODE_TYPES.ClassDeclaration)
		return handleClass(dec.declaration);
	else if (dec.declaration.type == AST_NODE_TYPES.TSEnumDeclaration)
		return handleEnum(dec.declaration);
	else if (dec.declaration.type == AST_NODE_TYPES.FunctionDeclaration) return;
	else {
		throw new Err(dec);
	}
}

function handleExport(
	ns: CppNamespace,
	file: string,
	body: a.ExportNamedDeclaration | a.ExportAllDeclaration
) {
	let newPath = path.join(path.dirname(file), body.source.value);
	if (fs.existsSync(newPath) && fs.statSync(newPath).isDirectory())
		newPath = path.join(newPath, 'index.ts');
	else if (!newPath.endsWith('.ts')) newPath = newPath + '.ts';
	console.log(`${file}: ${newPath}`);
	parseFile(ns, newPath);
}

function parseFile(ns: CppNamespace, file: string) {
	const ast = parse(fs.readFileSync(file).toString(), {
		programs: [program]
	});
	ast.body
		.filter((body) => body.type == AST_NODE_TYPES.ExportNamedDeclaration)
		.forEach((body: a.ExportNamedDeclaration) => {
			if (!body.source) {
				const ret = handleNamedDeclaration(body);
				if (ret) ns.body.push(ret);
			} else handleExport(ns, file, body);
		});
	ast.body
		.filter((body) => body.type == AST_NODE_TYPES.ExportAllDeclaration)
		.forEach((body: a.ExportAllDeclaration) => {
			let usedNs = ns;
			if ('exported' in body && body.exported) {
				const newNs = new CppNamespace(body.exported.name);
				ns.body.push(newNs);
				usedNs = newNs;
			}
			handleExport(usedNs, file, body);
		});
}

const globalNamespace = new CppNamespace('dto');
parseFile(globalNamespace, '../dto/index.ts');

const output_stream = fs.createWriteStream('../backend/src/dto.h');
output_stream.write(
	'#pragma once\n\n' +
		'#include <string>\n' +
		'#include <optional>\n' +
		'#include <vector>\n' +
		'#include <json/allocator.h>\n' +
		'#include "dto_extras.h"\n\n'
);
const output = new BetterWritable(output_stream);
globalNamespace.write(output);
globalNamespace.writeJsonAs('', output);