export function runGodoc()

in src/util.ts [1036:1111]
66 lines of code
17 McCabe index (conditional complexity)

export function runGodoc(
	cwd: string,
	packagePath: string,
	receiver: string | undefined,
	symbol: string,
	token: vscode.CancellationToken
) {
	if (!packagePath) {
		return Promise.reject(new Error('Package Path not provided'));
	}
	if (!symbol) {
		return Promise.reject(new Error('Symbol not provided'));
	}

	const goRuntimePath = getBinPath('go');
	if (!goRuntimePath) {
		return Promise.reject(new Error('Cannot find "go" binary. Update PATH or GOROOT appropriately'));
	}

	const getCurrentPackagePromise = path.isAbsolute(packagePath)
		? getCurrentPackage(packagePath)
		: Promise.resolve(packagePath);
	return getCurrentPackagePromise.then((packageImportPath) => {
		return new Promise<string>((resolve, reject) => {
			if (receiver) {
				receiver = receiver.replace(/^\*/, '');
				symbol = receiver + '.' + symbol;
			}

			const env = toolExecutionEnvironment();
			const args = ['doc', '-c', '-cmd', '-u', packageImportPath, symbol];
			const p = cp.execFile(goRuntimePath, args, { env, cwd }, (err, stdout, stderr) => {
				if (err) {
					return reject(err.message || stderr);
				}
				let doc = '';
				const godocLines = stdout.split('\n');
				if (!godocLines.length) {
					return resolve(doc);
				}

				// Recent versions of Go have started to include the package statement
				// tht we dont need.
				if (godocLines[0].startsWith('package ')) {
					godocLines.splice(0, 1);
					if (!godocLines[0].trim()) {
						godocLines.splice(0, 1);
					}
				}

				// Skip trailing empty lines
				let lastLine = godocLines.length - 1;
				for (; lastLine > 1; lastLine--) {
					if (godocLines[lastLine].trim()) {
						break;
					}
				}

				for (let i = 1; i <= lastLine; i++) {
					if (godocLines[i].startsWith('    ')) {
						doc += godocLines[i].substring(4) + '\n';
					} else if (!godocLines[i].trim()) {
						doc += '\n';
					}
				}
				return resolve(doc);
			});

			if (token) {
				token.onCancellationRequested(() => {
					killProcessTree(p);
				});
			}
		});
	});
}