Simplified wrapper around Node's native 'url' module

## url.coffee
# url.coffee
# by Aseem Kishore ( https://github.com/aseemk ), under MIT license
#
# A simplified wrapper around the native 'url' module that returns "live"
# objects: updates to properties are reflected in related properties. E.g.
# updates to the `port` property will be reflected on the `host` property.
#
# The public API and behavior are pretty close to the native 'url' module's:
# http://nodejs.org/docs/latest/api/url.html Currently lacking / known issues:
#
# - No support for `parseQueryString`; `query` can only be a string.
#   Similarly, no support for `slashesDenoteHost`.
#
# - Parsing of URLs beyond the initial parse (which uses the native 'url'
#   module) isn't thorough or strict right now. It assumes plenty.
#
# This is mainly just a simple and easy way to mutate/tweak URLs (e.g. to
# change a URL's port). Feedback and patches welcome! Thanks. =)

NativeURL = require 'url'

class URL

    # Private constructor:

    constructor: (href) ->
        @_reparse href

    # Language helpers:

    get = (props) =>
        @::__defineGetter__ name, getter for name, getter of props
    set = (props) =>
        @::__defineSetter__ name, setter for name, setter of props

    # Public properties:

    get href: ->
        # Postfix http/https/ftp/gopher/file protocols (trailing colon) with
        # colon-slash-slash; all others just colon:
        protocol = @protocol
        protocol += '//' if protocol.replace(/:$/, '') in ['http', 'https', 'ftp', 'gopher', 'file']
        # Add auth via @ if needed:
        auth = @auth
        auth += '@' if auth
        # Finally:
        "#{protocol}#{auth}#{@host}#{@pathname}#{@search}#{@hash}"
    set href: (val='') ->
        @_reparse val

    get protocol: -> @_protocol
    set protocol: (val='') ->
        # Lowercase, and ensure trailing colon:
        @_protocol = val.toLowerCase().replace(/:$/, '') + ':'

    # WARNING: The latest Node docs are inaccurate on host. They say host
    # includes auth, but it doesn't in practice:
    # https://github.com/joyent/node/issues/1626#issuecomment-5373917
    get host: ->
        host = @hostname
        host = [host, @port].join ':' if @port
        host
    set host: (val='') ->
        [@hostname, @port] = val.split ':'

    get auth: -> @_auth
    set auth: (@_auth='') ->

    get hostname: -> @_hostname
    set hostname: (@_hostname='') ->

    get port: -> @_port
    set port: (@_port='') ->

    get pathname: -> @_pathname
    set pathname: (val='') ->
        # Ensure trailing slash:
        @_pathname = '/' + val.replace(/^\//, '')

    get search: ->
        # Leading question mark if there's a query string:
        @query and "?#{@query}"
    set search: (val='') ->
        # Ensure leading question mark / strip it when assigning to @query:
        @_query = val.replace(/^\?/, '')

    get path: ->
        "#{@pathname}#{@search}"
    set path: (val='') ->
        [@pathname, @query] = val.split '?'

    get query: -> @_query
    set query: (@_query='') ->

    get hash: -> @_hash
    set hash: (val='') ->
        # Ensure leading anchor:
        @_hash = '#' + val.replace(/^#/, '')

    # Private methods:

    # Reparses the given URL and updates this instance in-place:
    _reparse: (href) ->
        # Save all properties as private(-ish) properties so that we can
        # validate/adjust updates to them, e.g. add trailing colons.
        # NOTE: All properties will be present -- missing ones will be the
        # empty string. This is consistent with browsers, but not w/ Node's
        # native 'url' module. That's fine hopefully?
        for prop, value of NativeURL.parse href
            @["_#{prop}"] = value or ''

    # Public methods:

    equals: (other) ->
        @href is other.href

    toString: ->
        @href

    @parse: (str) ->
        new URL str

    @format: (url) ->
        # Don't assume the given param will be an instance of this class:
        NativeURL.format url

    @resolve: (from, to) ->
        NativeURL.resolve from, to

# Export static functions only:
for name, func of URL when typeof func is 'function'
    exports[name] = func

## urltest.coffee
assert = require 'assert'
NativeURL = require 'url'
URL = require './url'

# Helper func for testing all getters:
test = (url, props) ->
    # Ignore 'slashes' property; we don't implement that yet.
    for prop, expected of props when prop isnt 'slashes'
        assert.equal url[prop], expected, """
            url.#{prop}:
                expected:   #{JSON.stringify expected}
                actual:     #{JSON.stringify url[prop]}
        """

# Test case: a full URL, straight from the Node docs!
# http://nodejs.org/docs/latest/api/url.html
STR = 'http://user:pass@host.com:8080/p/a/t/h?query=string#hash'
exp = NativeURL.parse STR

# Test initial parse:
url = URL.parse STR
test url, exp

# Test protocol set w/out trailing colon:
url.protocol = 'https'
exp.protocol = 'https:'
exp.href = exp.href.replace 'http:', 'https:'
test url, exp

# Test auth set:
url.auth = 'usr:pwd'
exp.auth = 'usr:pwd'
exp.href = exp.href.replace 'user:pass', 'usr:pwd'
test url, exp

# Test host set, clearing port:
url.host = 'example.com'
exp.host = 'example.com'
exp.port = ''
exp.hostname = 'example.com'
exp.href = exp.href.replace 'host.com:8080', 'example.com'
test url, exp

# Test hostname set:
url.hostname = 'foobar.net'
exp.hostname = 'foobar.net'
exp.host = 'foobar.net'
exp.href = exp.href.replace 'example.com', 'foobar.net'
test url, exp

# Test port set:
url.port = '1234'
exp.port = '1234'
exp.host = 'foobar.net:1234'
exp.href = exp.href.replace 'foobar.net', 'foobar.net:1234'
test url, exp

# Test path set w/out leading slash, clearing query string:
url.path = 'hello/world'
exp.path = '/hello/world'
exp.pathname = '/hello/world'
exp.search = ''
exp.query = ''
exp.href = exp.href.replace '/p/a/t/h?query=string', '/hello/world'
test url, exp

# Test pathname set w/out leading slash:
url.pathname = 'foo/bar'
exp.pathname = '/foo/bar'
exp.path = exp.path.replace '/hello/world', '/foo/bar'
exp.href = exp.href.replace '/hello/world', '/foo/bar'
test url, exp

# Test search set w/out leading question mark:
url.search = 'a=b'
exp.search = '?a=b'
exp.query = 'a=b'
exp.path = exp.path + '?a=b'
exp.href = exp.href.replace '/foo/bar', exp.path
test url, exp

# Test query set -- w/ (double) question mark:
# TODO Is this actually legitimate/correct?? It works...
url.query = '?foo=bar'
exp.query = '?foo=bar'
exp.search = '??foo=bar'
exp.path = exp.path.replace '?a=b', '??foo=bar'
exp.href = exp.href.replace '?a=b', '??foo=bar'
test url, exp

# Test hash set w/out leading anchor:
url.hash = 'baz'
exp.hash = '#baz'
exp.href = exp.href.replace '#hash', '#baz'
test url, exp

# Test hash clear:
url.hash = ''
exp.hash = '#'
exp.href = exp.href.replace '#baz', '#'
test url, exp

# Test search clear:
# TODO Should we be testing query clear too? Should question mark remain then?
url.search = ''
exp.search = ''
exp.query = ''
exp.path = exp.path.replace '??foo=bar', ''
exp.href = exp.href.replace '??foo=bar', ''
test url, exp

# Test path clear:
url.path = ''
exp.path = '/'
exp.pathname = '/'
exp.href = exp.href.replace '/foo/bar', '/'
test url, exp

# Test port clear:
url.port = ''
exp.port = ''
exp.host = exp.host.replace ':1234', ''
exp.href = exp.href.replace ':1234', ''
test url, exp

# Test auth clear:
url.auth = ''
exp.auth = ''
exp.href = exp.href.replace 'usr:pwd@', ''
test url, exp

# Finally, test set href:
url.href = STR
exp = NativeURL.parse STR
test url, exp

console.log 'All tests passed!'