// Copyright (c) 2017 Daniel Oaks <daniel@danieloaks.net>
// released under the MIT license

package irc

import (
	"fmt"
	"sort"
	"strings"

	"github.com/goshuirc/irc-go/ircfmt"
	"github.com/oragono/oragono/irc/modes"
	"github.com/oragono/oragono/irc/sno"
	"github.com/oragono/oragono/irc/utils"
)

const chanservHelp = `ChanServ lets you register and manage channels.

To see in-depth help for a specific ChanServ command, try:
    $b/CS HELP <command>$b

Here are the commands you can use:
%s`

type csCommand struct {
	capabs    []string // oper capabs the given user has to have to access this command
	handler   func(server *Server, client *Client, command, params string, rb *ResponseBuffer)
	help      string
	helpShort string
	oper      bool // true if the user has to be an oper to use this command
}

var (
	chanservCommands = map[string]*csCommand{
		"help": {
			help: `Syntax: $bHELP [command]$b

HELP returns information on the given command.`,
			helpShort: `$bHELP$b shows in-depth information about commands.`,
		},
		"op": {
			handler: csOpHandler,
			help: `Syntax: $bOP #channel [nickname]$b

OP makes the given nickname, or yourself, a channel admin. You can only use
this command if you're the founder of the channel.`,
			helpShort: `$bOP$b makes the given user (or yourself) a channel admin.`,
		},
		"register": {
			handler: csRegisterHandler,
			help: `Syntax: $bREGISTER #channel$b

REGISTER lets you own the given channel. If you rejoin this channel, you'll be
given admin privs on it. Modes set on the channel and the topic will also be
remembered.`,
			helpShort: `$bREGISTER$b lets you own a given channel.`,
		},
	}
)

// csNotice sends the client a notice from ChanServ
func csNotice(rb *ResponseBuffer, text string) {
	rb.Add(nil, "ChanServ", "NOTICE", rb.target.Nick(), text)
}

// chanservReceiveNotice handles NOTICEs that ChanServ receives.
func (server *Server) chanservNoticeHandler(client *Client, message string, rb *ResponseBuffer) {
	// do nothing
}

// chanservReceiveNotice handles NOTICEs that ChanServ receives.
func (server *Server) chanservPrivmsgHandler(client *Client, message string, rb *ResponseBuffer) {
	commandName, params := utils.ExtractParam(message)
	commandName = strings.ToLower(commandName)

	commandInfo := chanservCommands[commandName]
	if commandInfo == nil {
		csNotice(rb, client.t("Unknown command. To see available commands, run /CS HELP"))
		return
	}

	if commandInfo.oper && !client.HasMode(modes.Operator) {
		csNotice(rb, client.t("Command restricted"))
		return
	}

	if 0 < len(commandInfo.capabs) && !client.HasRoleCapabs(commandInfo.capabs...) {
		csNotice(rb, client.t("Command restricted"))
		return
	}

	// custom help handling here to prevent recursive init loop
	if commandName == "help" {
		csHelpHandler(server, client, commandName, params, rb)
		return
	}

	if commandInfo.handler == nil {
		csNotice(rb, client.t("Command error. Please report this to the developers"))
		return
	}

	server.logger.Debug("chanserv", fmt.Sprintf("Client %s ran command %s", client.Nick(), commandName))

	commandInfo.handler(server, client, commandName, params, rb)
}

func csHelpHandler(server *Server, client *Client, command, params string, rb *ResponseBuffer) {
	csNotice(rb, ircfmt.Unescape(client.t("*** $bChanServ HELP$b ***")))

	if params == "" {
		// show general help
		var shownHelpLines sort.StringSlice
		for _, commandInfo := range chanservCommands {
			// skip commands user can't access
			if commandInfo.oper && !client.HasMode(modes.Operator) {
				continue
			}
			if 0 < len(commandInfo.capabs) && !client.HasRoleCapabs(commandInfo.capabs...) {
				continue
			}

			shownHelpLines = append(shownHelpLines, "    "+client.t(commandInfo.helpShort))
		}

		// sort help lines
		sort.Sort(shownHelpLines)

		// assemble help text
		assembledHelpLines := strings.Join(shownHelpLines, "\n")
		fullHelp := ircfmt.Unescape(fmt.Sprintf(client.t(chanservHelp), assembledHelpLines))

		// push out help text
		for _, line := range strings.Split(fullHelp, "\n") {
			csNotice(rb, line)
		}
	} else {
		commandInfo := chanservCommands[strings.ToLower(strings.TrimSpace(params))]
		if commandInfo == nil {
			csNotice(rb, client.t("Unknown command. To see available commands, run /cs HELP"))
		} else {
			for _, line := range strings.Split(ircfmt.Unescape(client.t(commandInfo.help)), "\n") {
				csNotice(rb, line)
			}
		}
	}

	csNotice(rb, ircfmt.Unescape(client.t("*** $bEnd of ChanServ HELP$b ***")))
}

func csOpHandler(server *Server, client *Client, command, params string, rb *ResponseBuffer) {
	channelName, clientToOp := utils.ExtractParam(params)

	if channelName == "" {
		csNotice(rb, ircfmt.Unescape(client.t("Syntax: $bOP #channel [nickname]$b")))
		return
	}

	clientToOp = strings.TrimSpace(clientToOp)

	channelKey, err := CasefoldChannel(channelName)
	if err != nil {
		csNotice(rb, client.t("Channel name is not valid"))
		return
	}

	channelInfo := server.channels.Get(channelKey)
	if channelInfo == nil {
		csNotice(rb, client.t("Channel does not exist"))
		return
	}

	clientAccount := client.Account()

	if clientAccount == "" {
		csNotice(rb, client.t("You must be logged in to op on a channel"))
		return
	}

	if clientAccount != channelInfo.Founder() {
		csNotice(rb, client.t("You must be the channel founder to op"))
		return
	}

	var target *Client
	if clientToOp != "" {
		casefoldedNickname, err := CasefoldName(clientToOp)
		target = server.clients.Get(casefoldedNickname)
		if err != nil || target == nil {
			csNotice(rb, client.t("Could not find given client"))
			return
		}
	} else {
		target = client
	}

	// give them privs
	givenMode := modes.ChannelOperator
	if client == target {
		givenMode = modes.ChannelFounder
	}
	change := channelInfo.applyModeMemberNoMutex(target, givenMode, modes.Add, client.NickCasefolded(), rb)
	if change != nil {
		//TODO(dan): we should change the name of String and make it return a slice here
		//TODO(dan): unify this code with code in modes.go
		args := append([]string{channelName}, strings.Split(change.String(), " ")...)
		for _, member := range channelInfo.Members() {
			member.Send(nil, fmt.Sprintf("ChanServ!services@%s", client.server.name), "MODE", args...)
		}
	}

	csNotice(rb, fmt.Sprintf(client.t("Successfully op'd in channel %s"), channelName))

	server.logger.Info("chanserv", fmt.Sprintf("Client %s op'd [%s] in channel %s", client.nick, clientToOp, channelName))
	server.snomasks.Send(sno.LocalChannels, fmt.Sprintf(ircfmt.Unescape("Client $c[grey][$r%s$c[grey]] CS OP'd $c[grey][$r%s$c[grey]] in channel $c[grey][$r%s$c[grey]]"), client.nickMaskString, clientToOp, channelName))
}

func csRegisterHandler(server *Server, client *Client, command, params string, rb *ResponseBuffer) {
	if !server.channelRegistrationEnabled {
		csNotice(rb, client.t("Channel registration is not enabled"))
		return
	}

	channelName := strings.TrimSpace(params)
	if channelName == "" {
		csNotice(rb, ircfmt.Unescape(client.t("Syntax: $bREGISTER #channel$b")))
		return
	}

	channelKey, err := CasefoldChannel(channelName)
	if err != nil {
		csNotice(rb, client.t("Channel name is not valid"))
		return
	}

	channelInfo := server.channels.Get(channelKey)
	if channelInfo == nil || !channelInfo.ClientIsAtLeast(client, modes.ChannelOperator) {
		csNotice(rb, client.t("You must be an oper on the channel to register it"))
		return
	}

	if client.Account() == "" {
		csNotice(rb, client.t("You must be logged in to register a channel"))
		return
	}

	// this provides the synchronization that allows exactly one registration of the channel:
	err = channelInfo.SetRegistered(client.Account())
	if err != nil {
		csNotice(rb, err.Error())
		return
	}

	// registration was successful: make the database reflect it
	go server.channelRegistry.StoreChannel(channelInfo, true)

	csNotice(rb, fmt.Sprintf(client.t("Channel %s successfully registered"), channelName))

	server.logger.Info("chanserv", fmt.Sprintf("Client %s registered channel %s", client.nick, channelName))
	server.snomasks.Send(sno.LocalChannels, fmt.Sprintf(ircfmt.Unescape("Channel registered $c[grey][$r%s$c[grey]] by $c[grey][$r%s$c[grey]]"), channelName, client.nickMaskString))

	// give them founder privs
	change := channelInfo.applyModeMemberNoMutex(client, modes.ChannelFounder, modes.Add, client.NickCasefolded(), rb)
	if change != nil {
		//TODO(dan): we should change the name of String and make it return a slice here
		//TODO(dan): unify this code with code in modes.go
		args := append([]string{channelName}, strings.Split(change.String(), " ")...)
		for _, member := range channelInfo.Members() {
			member.Send(nil, fmt.Sprintf("ChanServ!services@%s", client.server.name), "MODE", args...)
		}
	}
}