var core = require('./core'); var fs = require('fs'); var path = require('path'); var caller = require('./caller.js'); var nodeModulesPaths = require('./node-modules-paths.js'); var normalizeOptions = require('./normalize-options.js');

var defaultIsFile = function isFile(file) {

try {
    var stat = fs.statSync(file);
} catch (e) {
    if (e && (e.code === 'ENOENT' || e.code === 'ENOTDIR')) return false;
    throw e;
}
return stat.isFile() || stat.isFIFO();

};

var defaultIsDir = function isDirectory(dir) {

try {
    var stat = fs.statSync(dir);
} catch (e) {
    if (e && (e.code === 'ENOENT' || e.code === 'ENOTDIR')) return false;
    throw e;
}
return stat.isDirectory();

};

var maybeUnwrapSymlink = function maybeUnwrapSymlink(x, opts) {

if (opts && opts.preserveSymlinks === false) {
    try {
        return fs.realpathSync(x);
    } catch (realPathErr) {
        if (realPathErr.code !== 'ENOENT') {
            throw realPathErr;
        }
    }
}
return x;

};

module.exports = function (x, options) {

if (typeof x !== 'string') {
    throw new TypeError('Path must be a string.');
}
var opts = normalizeOptions(x, options);

var isFile = opts.isFile || defaultIsFile;
var readFileSync = opts.readFileSync || fs.readFileSync;
var isDirectory = opts.isDirectory || defaultIsDir;

var extensions = opts.extensions || ['.js'];
var basedir = opts.basedir || path.dirname(caller());
var parent = opts.filename || basedir;

opts.paths = opts.paths || [];

// ensure that `basedir` is an absolute path at this point, resolving against the process' current working directory
var absoluteStart = maybeUnwrapSymlink(path.resolve(basedir), opts);

if ((/^(?:\.\.?(?:\/|$)|\/|([A-Za-z]:)?[/\\])/).test(x)) {
    var res = path.resolve(absoluteStart, x);
    if (x === '..' || x.slice(-1) === '/') res += '/';
    var m = loadAsFileSync(res) || loadAsDirectorySync(res);
    if (m) return maybeUnwrapSymlink(m, opts);
} else if (core[x]) {
    return x;
} else {
    var n = loadNodeModulesSync(x, absoluteStart);
    if (n) return maybeUnwrapSymlink(n, opts);
}

if (core[x]) return x;

var err = new Error("Cannot find module '" + x + "' from '" + parent + "'");
err.code = 'MODULE_NOT_FOUND';
throw err;

function loadAsFileSync(x) {
    var pkg = loadpkg(path.dirname(x));

    if (pkg && pkg.dir && pkg.pkg && opts.pathFilter) {
        var rfile = path.relative(pkg.dir, x);
        var r = opts.pathFilter(pkg.pkg, x, rfile);
        if (r) {
            x = path.resolve(pkg.dir, r); // eslint-disable-line no-param-reassign
        }
    }

    if (isFile(x)) {
        return x;
    }

    for (var i = 0; i < extensions.length; i++) {
        var file = x + extensions[i];
        if (isFile(file)) {
            return file;
        }
    }
}

function loadpkg(dir) {
    if (dir === '' || dir === '/') return;
    if (process.platform === 'win32' && (/^\w:[/\\]*$/).test(dir)) {
        return;
    }
    if ((/[/\\]node_modules[/\\]*$/).test(dir)) return;

    var pkgfile = path.join(dir, 'package.json');

    if (!isFile(pkgfile)) {
        return loadpkg(path.dirname(dir));
    }

    var body = readFileSync(pkgfile);

    try {
        var pkg = JSON.parse(body);
    } catch (jsonErr) {}

    if (pkg && opts.packageFilter) {
        pkg = opts.packageFilter(pkg, dir);
    }

    return { pkg: pkg, dir: dir };
}

function loadAsDirectorySync(x) {
    var pkgfile = path.join(x, '/package.json');
    if (isFile(pkgfile)) {
        try {
            var body = readFileSync(pkgfile, 'UTF8');
            var pkg = JSON.parse(body);
        } catch (e) {}

        if (opts.packageFilter) {
            pkg = opts.packageFilter(pkg, x);
        }

        if (pkg.main) {
            if (typeof pkg.main !== 'string') {
                var mainError = new TypeError('package “' + pkg.name + '” `main` must be a string');
                mainError.code = 'INVALID_PACKAGE_MAIN';
                throw mainError;
            }
            if (pkg.main === '.' || pkg.main === './') {
                pkg.main = 'index';
            }
            try {
                var m = loadAsFileSync(path.resolve(x, pkg.main));
                if (m) return m;
                var n = loadAsDirectorySync(path.resolve(x, pkg.main));
                if (n) return n;
            } catch (e) {}
        }
    }

    return loadAsFileSync(path.join(x, '/index'));
}

function loadNodeModulesSync(x, start) {
    var dirs = nodeModulesPaths(start, opts, x);
    for (var i = 0; i < dirs.length; i++) {
        var dir = dirs[i];
        if (isDirectory(dir)) {
            var m = loadAsFileSync(path.join(dir, '/', x));
            if (m) return m;
            var n = loadAsDirectorySync(path.join(dir, '/', x));
            if (n) return n;
        }
    }
}

};