/**
 * @author Toru Nagashima
 * @copyright 2016 Toru Nagashima. All rights reserved.
 * See LICENSE file in root directory for full license.
 */
"use strict"

//------------------------------------------------------------------------------
// Requirements
//------------------------------------------------------------------------------

const path = require("path")
const resolve = require("resolve")

//------------------------------------------------------------------------------
// Helpers
//------------------------------------------------------------------------------

/**
 * Resolve the given id to file paths.
 * @param {boolean} isModule The flag which indicates this id is a module.
 * @param {string} id The id to resolve.
 * @param {object} options The options of node-resolve module.
 * It requires `options.basedir`.
 * @returns {string|null} The resolved path.
 */
function getFilePath(isModule, id, options) {
    try {
        return resolve.sync(id, options)
    }
    catch (_err) {
        if (isModule) {
            return null
        }
        return path.resolve(options.basedir, id)
    }
}

/**
 * Gets the module name of a given path.
 *
 * e.g. `eslint/lib/ast-utils` -> `eslint`
 *
 * @param {string} nameOrPath - A path to get.
 * @returns {string} The module name of the path.
 */
function getModuleName(nameOrPath) {
    let end = nameOrPath.indexOf("/")
    if (end !== -1 && nameOrPath[0] === "@") {
        end = nameOrPath.indexOf("/", 1 + end)
    }

    return end === -1 ? nameOrPath : nameOrPath.slice(0, end)
}

//------------------------------------------------------------------------------
// Public Interface
//------------------------------------------------------------------------------

/**
 * Information of an import target.
 */
module.exports = class ImportTarget {
    /**
     * Initialize this instance.
     * @param {ASTNode} node - The node of a `require()` or a module declaraiton.
     * @param {string} name - The name of an import target.
     * @param {object} options - The options of `node-resolve` module.
     */
    constructor(node, name, options) {
        const isModule = !/^(?:[./\\]|\w+:)/.test(name)

        /**
         * The node of a `require()` or a module declaraiton.
         * @type {ASTNode}
         */
        this.node = node

        /**
         * The name of this import target.
         * @type {string}
         */
        this.name = name

        /**
         * The full path of this import target.
         * If the target is a module and it does not exist then this is `null`.
         * @type {string|null}
         */
        this.filePath = getFilePath(isModule, name, options)

        /**
         * The module name of this import target.
         * If the target is a relative path then this is `null`.
         * @type {string|null}
         */
        this.moduleName = isModule ? getModuleName(name) : null
    }
}