import { CliOptions, CliParsedCommandHandler, ParsedCliCommand } from './types';
import { isFunction } from './utils';

export const createRunHandler = (cliOptions: CliOptions = {}): CliParsedCommandHandler => {
    const runHandler = async (parsed: ParsedCliCommand): Promise<void | number> => {
        // determine if a passed command option has an associated handler (to short-cirucuit command handler, e.g. help/version)
        const commandOption = Object.keys(parsed.options)
            .filter(o => typeof parsed.options[o] !== 'undefined')
            .find(o => !!(parsed.optionDefinitions[o] && parsed.optionDefinitions[o].commandHandler));

        // get handler from command option, then global handler, then the individual command's handler
        const parsedCmdHandler = commandOption
            ? parsed.optionDefinitions[commandOption].commandHandler
            : cliOptions.globalHandler;

        if (parsedCmdHandler) {
            if (isFunction(parsedCmdHandler)) {
                return Promise.resolve(parsedCmdHandler(parsed));
            } else {
                throw new Error(`runHandler Failed: commandHandler is not a function`);
            }
        } else if (parsed.command.handler) {
            return Promise.resolve(parsed.command.handler(parsed.arguments, parsed.options, parsed));
        }
    };

    return runHandler;
};