--
-- Minetest chat channels
--
-- Allows you to send all messages as PMs.
--

local main_channel = '#main'
local channel = main_channel
local storage = minetest.get_mod_storage()
local channels = {}
local messages_sent = 0
local buffer = {}
local msgprefix
local localplayer = '[you]'
local show_main_channel = true

if storage:get_string('channels') then
    channels = loadstring(storage:get_string('channels'))()
end

if not channels then channels = {} end

minetest.register_on_connect(function()
    localplayer = minetest.localplayer:get_name()
end)

local player_in_channel = function(v, c)
    local in_channel = false
    if not c then c = channel end
    if channels[c] then
        for p = 1, #channels[c] do
            if channels[c][p] == v then
                in_channel = p
                break
            end
        end
    end
    return in_channel
end

local save = function()
    storage:set_string('channels', minetest.serialize(channels))
end

local get_channel_users = function(c)
    if not c then c = channel end
    if c == main_channel then return false end
    local prefix = c:sub(1, 1)
    local name = c:sub(2)
    if prefix == '#' then
        local u = channels[name]
        if u and #u > 0 then
            local i = player_in_channel(localplayer, name)
            if i then
                table.remove(channels[name], i)
                save()
            end
            return channels[name]
        else
            if u then
                channels[name] = false
            end
            show_main_channel = true
            channel = main_channel
            return false
        end
    elseif prefix == '@' then
        return {name}
    else
        show_main_channel = true
        channel = main_channel
        return false
    end
end

minetest.register_on_sending_chat_messages(function(msg)
    local cmdprefix = msg:sub(1, 1)
    local c = channel
    if cmdprefix == '/' or cmdprefix == '.' then
        return
    elseif cmdprefix == '#' or cmdprefix == '@' then
        local s, e = msg:find(' ')
        if s then
            c = msg:sub(1, s - 1)
            msg = msg:sub(s + 1)
        else
            if cmdprefix == '@' or channels[msg:sub(2)] or msg == main_channel
              then
                channel = msg
                if channel == main_channel then 
                    show_main_channel = true
                end
                minetest.display_chat_message('You have changed chat channels to '
                    .. channel)
                return true
            end
            c = msg
            msg = ''
        end
        if c == main_channel then
            show_main_channel = true
            minetest.send_chat_message(msg)
            return true
        elseif cmdprefix == '#' and not channels[c:sub(2)] then
            minetest.display_chat_message('The channel ' .. c ..
                ' was not found.')
            return true
        end
    end
    local players = get_channel_users(c)
    if not players then return end
    table.insert(buffer, '-' .. c .. '- <' .. localplayer .. '> ' .. msg)
    messages_sent = messages_sent + #players
    for p = 1, #players do
        minetest.run_server_chatcommand('msg', players[p] .. ' -' .. c ..
            '- ' .. msg)
    end
    return true
end)

minetest.register_on_receiving_chat_messages(function(msg)
    local m = minetest.strip_colors(msg)
    if m == 'Message sent.' or m:match('^The player .* is not online.$')
      then
        if messages_sent > 0 then
          messages_sent = messages_sent - 1
          if messages_sent == 0 and #buffer > 0 then
              minetest.display_chat_message(buffer[1])
              table.remove(buffer, 1)
          end
          return true
        end
    elseif m:sub(1, 1) == '<' then
        if not show_main_channel then return true end
        local hijack = false
        if channel == main_channel then
            for _ in pairs(channels) do
                hijack = true
                break
            end
        else
            hijack = true
        end
        if hijack then
            minetest.display_chat_message('-' .. main_channel .. '- ' .. msg)
            return true
        end
    elseif m:match('^PM from [^\\- ]*: -[^ ]*- ') then
        local s, e = msg:find('-[^ ]*- ')
        if not s then return end
        local chan = msg:sub(s + 2, e - 2)
        local text = msg:sub(e + 1)
        local user = m:sub(9)
        local s, e = user:find(': ')
        local user = user:sub(1, s - 1)
        
        if player_in_channel(user, chan) then
            minetest.display_chat_message('-#' .. chan .. '- <' .. user ..
                '> ' .. text)
            return true
        end
    end
end)

minetest.register_chatcommand('add_to_channel', {
    params = "<victim> [channel]",
    description = "Add a player to a local chat channel.",
    func = function(param)
        local s, e = param:find(' ')
        local v
        local c
        if s then
            v = param:sub(1, s - 1)
            c = param:sub(s + 1)
        else
            v = param
            c = channel
            if v:find(' ') then v = '' end
        end
        if v == '' or c == '' or c:find(' ') or c:sub(1, 1) ~= '#' then
            return false, "Invalid syntax! Usage: .add_to_channel <victim> [channel]"
        elseif c == main_channel then
            return false, "You cannot add users to the main channel!"
        elseif v == localplayer then
            return false, "You cannot add yourself to a channel!"
        end
        c = c:sub(2)
        if channels[c] then
            if player_in_channel(v, c) then
                return true, "That player is already in the channel!"
            end
        else
            channels[c] = {}
        end
        table.insert(channels[c], v)
        save()
        return true, "Done!"
    end
})

minetest.register_chatcommand('remove_from_channel', {
    params = "<victim> [channel]",
    description = "Remove a player from a local chat channel.",
    func = function(param)
        local s, e = param:find(' ')
        local v
        local c
        if s then
            v = param:sub(1, s - 1)
            c = param:sub(s + 1)
        else
            v = param
            c = channel
            if v:find(' ') then v = '' end
        end
        if v == '' or c == '' or c:find(' ') or c:sub(1, 1) ~= '#' then
            return false, "Invalid syntax! Usage: .remove_from_channel <victim> [channel]"
        elseif c == main_channel then
            return false, "You cannot remove users to the main channel!"
        elseif v == localplayer then
            return false, "You cannot remove yourself from a channel!"
        end
        c = c:sub(2)
        local in_channel = player_in_channel(v, c)
        if in_channel then
            table.remove(channels[c], in_channel)
            if #channels[c] < 1 then channels[c] = nil end
            save()
            return true, "Done!"
        else
            return true, "The player is not in the channel!"
        end
    end
})

minetest.register_chatcommand('list_channels', {
    params = "",
    description = "Lists the channels.",
    func = function()
        local c = {}
        for i, _ in pairs(channels) do
            table.insert(c, i)
        end
        return true, "List of channels: " .. table.concat(c, ', ')
    end
})

minetest.register_chatcommand('delete_channel', {
    params = "<channel>",
    description = "Removes a channel.",
    func = function(c)
        if c:sub(1, 1) ~= '#' then
            return false, "The channel must start with a #."
        end
        c = c:sub(2)
        if not channels[c] then
            return false, "The channel does not exist!"
        end
        channels[c] = nil
        save()
        return true, "Channel #" .. c .. " is no longer."
    end
})

minetest.register_chatcommand('toggle_' .. main_channel:sub(2), {
    params = "",
    description = "Toggle between showing and hiding messages from "
        .. main_channel .. ".",
    func = function(c)
        if not show_main_channel then
            show_main_channel = true
            return true, "You will now start to receive messages from "
                .. main_channel .. "."
        elseif channel == main_channel then
            return false, "You are currently in " .. main_channel
                .. "! Please change channels first."
        else
            show_main_channel = false
            return true, "You will no longer receive messages from "
                .. main_channel .. "."
        end
    end
})

minetest.register_chatcommand('who', {
    params = "[channel]",
    description = "List players in the current chat channel.",
    func = function(c)
        if c == '' then c = channel end
        if c:sub(1, 1) ~= '#' then
            return false, "The channel must start with a #."
        end
        c = c:sub(2)
        local players
        if c == main_channel:sub(2) then
            players = minetest.get_player_names()
        elseif channels[c] then
            local u = table.unpack or unpack
            players = {localplayer,
                u(channels[c])}
        else
            players = {}
        end
        table.sort(players)
        players = table.concat(players, ', ')
        return true, "List of players in #" .. c .. ": " .. players
    end
})