/**
 * Wrap operations for consumption in Node
 *
 * @author d98762625 [d98762625@gmail.com]
 * @copyright Crown Copyright 2018
 * @license Apache-2.0
 */

import Dish from "../core/Dish";
import log from "loglevel";

/**
 * Extract default arg value from operation argument
 * @param {Object} arg - an arg from an operation
 */
function extractArg(arg) {
    if (arg.type === "option" || arg.type === "editableOption") {
        return arg.value[0];
    }

    return arg.value;
}

/**
 * Wrap an operation to be consumed by node API.
 * new Operation().run() becomes operation()
 * Perform type conversion on input
 * @param {Operation} Operation
 * @returns {Function} The operation's run function, wrapped in
 * some type conversion logic
 */
export function wrap(Operation) {
    /**
     * Wrapped operation run function
     */
    return async (input, args=null) => {
        const operation = new Operation();
        const dish = new Dish(input);

        try {
            dish.findType();
        } catch (e) {
            log.debug(e);
        }

        if (!args) {
            args = operation.args.map(extractArg);
        } else {
            // Allows single arg ops to have arg defined not in array
            if (!(args instanceof Array)) {
                args = [args];
            }
        }
        const transformedInput = await dish.get(Dish.typeEnum(operation.inputType));
        return operation.run(transformedInput, args);
    };
}

/**
 * 
 * @param searchTerm 
 */
export function search(searchTerm) {

}


/**
 * Extract properties from an operation by instantiating it and
 * returning some of its properties for reference.
 * @param {Operation}  Operation - the operation to extract info from
 * @returns {Object} operation properties
 */
function extractOperationInfo(Operation) {
    const operation = new Operation();
    return {
        name: operation.name,
        module: operation.module,
        description: operation.description,
        inputType: operation.inputType,
        outputType: operation.outputType,
        args: Object.assign([], operation.args),
    };
}


/**
 * @param {Object} operations - an object filled with operations.
 * @param {String} searchTerm - the name of the operation to get help for.
 * Case and whitespace are ignored in search.
 * @returns {Object} listing properties of function
 */
export function help(operations, searchTerm) {
    if (typeof searchTerm === "string") {
        const operation = operations[Object.keys(operations).find(o =>
            o.toLowerCase() === searchTerm.replace(/ /g, "").toLowerCase())];
        if (operation) {
            return extractOperationInfo(operation);
        }
    }
    return null;
}


/**
 * SomeName => someName
 * @param {String} name - string to be altered
 * @returns {String} decapitalised
 */
export function decapitalise(name) {
    return `${name.charAt(0).toLowerCase()}${name.substr(1)}`;
}