ergo/irc/isupport.go

// Copyright (c) 2016- Daniel Oaks <daniel@danieloaks.net>
// released under the MIT license

package irc

import "fmt"

const isupportSupportedString = "are supported by this server"

// ISupportList holds a list of ISUPPORT tokens
type ISupportList struct {
	Tokens      map[string]*string
	CachedReply [][]string
}

// NewISupportList returns a new ISupportList
func NewISupportList() *ISupportList {
	var il ISupportList
	il.Tokens = make(map[string]*string)
	il.CachedReply = make([][]string, 0)
	return &il
}

// Add adds an RPL_ISUPPORT token to our internal list
func (il *ISupportList) Add(name string, value string) {
	il.Tokens[name] = &value
}

// AddNoValue adds an RPL_ISUPPORT token that does not have a value
func (il *ISupportList) AddNoValue(name string) {
	il.Tokens[name] = nil
}

// getTokenString gets the appropriate string for a token+value.
func getTokenString(name string, value *string) string {
	if value == nil {
		return name
	}
	return fmt.Sprintf("%s=%s", name, *value)
}

// GetDifference returns the difference between two token lists.
func (il *ISupportList) GetDifference(newil *ISupportList) [][]string {
	replies := make([][]string, 0)
	var length int     // Length of the current cache
	var cache []string // Token list cache

	// append removed tokens
	for name := range il.Tokens {
		_, exists := newil.Tokens[name]
		if exists {
			continue
		}

		token := fmt.Sprintf("-%s", name)

		if len(token)+length <= maxLastArgLength {
			// account for the space separating tokens
			if len(cache) > 0 {
				length++
			}
			cache = append(cache, token)
			length += len(token)
		}

		if len(cache) == 13 || len(token)+length >= maxLastArgLength {
			cache = append(cache, isupportSupportedString)
			replies = append(replies, cache)
			cache = make([]string, 0)
			length = 0
		}
	}

	// append added tokens
	for name, value := range newil.Tokens {
		newval, exists := il.Tokens[name]
		if exists && *value == *newval {
			continue
		}

		token := getTokenString(name, value)

		if len(token)+length <= maxLastArgLength {
			// account for the space separating tokens
			if len(cache) > 0 {
				length++
			}
			cache = append(cache, token)
			length += len(token)
		}

		if len(cache) == 13 || len(token)+length >= maxLastArgLength {
			cache = append(cache, isupportSupportedString)
			replies = append(replies, cache)
			cache = make([]string, 0)
			length = 0
		}
	}

	if len(cache) > 0 {
		cache = append(cache, isupportSupportedString)
		replies = append(replies, cache)
	}

	return replies
}

// RegenerateCachedReply regenerates the cached RPL_ISUPPORT reply
func (il *ISupportList) RegenerateCachedReply() {
	il.CachedReply = make([][]string, 0)
	var length int     // Length of the current cache
	var cache []string // Token list cache

	for name, value := range il.Tokens {
		token := getTokenString(name, value)

		if len(token)+length <= maxLastArgLength {
			// account for the space separating tokens
			if len(cache) > 0 {
				length++
			}
			cache = append(cache, token)
			length += len(token)
		}

		if len(cache) == 13 || len(token)+length >= maxLastArgLength {
			cache = append(cache, isupportSupportedString)
			il.CachedReply = append(il.CachedReply, cache)
			cache = make([]string, 0)
			length = 0
		}
	}

	if len(cache) > 0 {
		cache = append(cache, isupportSupportedString)
		il.CachedReply = append(il.CachedReply, cache)
	}
}

// RplISupport outputs our ISUPPORT lines to the client. This is used on connection and in VERSION responses.
func (client *Client) RplISupport() {
	for _, tokenline := range client.server.isupport.CachedReply {
		// ugly trickery ahead
		client.Send(nil, client.server.name, RPL_ISUPPORT, append([]string{client.nick}, tokenline...)...)
	}
}