xfix/showdown2irc

// showdown2irc - use Showdown chat with an IRC client
// Copyright (C) 2016 Konrad Borowski
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package showdown

import (
    "bytes"
    "encoding/json"
    "io/ioutil"
    "net/http"
    "net/url"
    "regexp"
    "strings"
    "unicode"
    "unicode/utf8"
)

// UserID represents a user ID. It's distinct from standard strings to
// prevent accidentally mistaking usernames with IDs
type UserID string

// RoomID represents a room ID.
type RoomID string

// SplitUser given a string with a rank and username provided User object
func SplitUser(name string) User {
    auth, size := utf8.DecodeRuneInString(name)
    return User{auth, name[size:]}
}

// ToID converts a username to its ID.
func ToID(name string) UserID {
    var buffer bytes.Buffer
    for _, character := range name {
        character = unicode.ToLower(character)
        if 'a' <= character && character <= 'z' || '0' <= character && character <= '9' {
            buffer.WriteRune(character)
        }
    }
    return UserID(buffer.String())
}

type serverDoesNotExistError struct{}

func (serverDoesNotExistError) Error() string {
    return "Server does not exist"
}

var configurationRegexp = regexp.MustCompile(`(?m)^var config = (.*);$`)

type ServerAddress struct {
    Host string
    Port uint16
}

func findConfiguration(name string) (ServerAddress, error) {
    if !strings.Contains(name, ".") {
        name += ".psim.us"
    }
    serverConfiguration, err := downloadConfiguration(name)
    if err != nil {
        return ServerAddress{}, err
    }
    // Crossdomain API doesn't provide server information for main server.
    if serverConfiguration.Host == "showdown" {
        serverConfiguration.Host = "sim2.psim.us"
        serverConfiguration.Port = 443
    }
    return serverConfiguration, nil
}

func downloadConfiguration(server string) (_ ServerAddress, err error) {
    escapedName := url.QueryEscape(server)
    res, err := http.Get("https://play.pokemonshowdown.com/crossdomain.php?host=" + escapedName)
    if err != nil {
        return
    }
    contents, err := ioutil.ReadAll(res.Body)
    res.Body.Close()
    if err != nil {
        return
    }
    return parseConfiguration(contents)
}

func parseConfiguration(crossDomainOutput []byte) (serverConfiguration ServerAddress, err error) {
    matches := configurationRegexp.FindSubmatch(crossDomainOutput)
    if matches == nil {
        err = new(serverDoesNotExistError)
        return
    }
    jsonJSONData := matches[1]
    var jsonData string
    err = json.Unmarshal(jsonJSONData, &jsonData)
    if err != nil {
        return
    }
    err = json.Unmarshal([]byte(jsonData), &serverConfiguration)
    return
}