-- [[ A framework to track GMCP module usage ]] --

module("gmod", package.seeall)

local registeredUsers = registeredUsers or {}
local registeredModules = registeredModules or {}

-- Central text output function for the module.
function print(text)
  cecho(string.format("\n<yellow>[GMCP Tracker] <white>%s\n", text))
end

-- Register a user to the system.
function registerUser(user)
  if registeredUsers[user] then
    return "user exists"
  else
    registeredUsers[user] = true
  end

  return "user registered"
end

-- Add a user to a module
local function addUser(user, module)
  registeredModules[module][user] = true

  return "user added"
end

-- Drop a user from a module
local function dropUser(user, module)
  if not registeredModules[module] then
    return "no registered module"
  end
  if not registeredModules[module][user] then
    return "user not linked"
  end
  registeredModules[module][user] = nil

  return "user dropped"
end

-- Get the user count of a module.
local function getUserCount(module)
  if not registeredModules[module] then
    return 0
  end
  local count = 0
  for i, v in pairs(registeredModules[module]) do
    count = count + 1
  end
  return count
end

-- Check to see if the module is registered. Return a user list if it is.
function isRegisteredModule(mod)
  if not registeredModules[mod] then
    return false
  end
  return registeredModules[mod]
end

-- Enable a module that isn't already enabled, and register its use to a user.
function enableModule(user, module)
  registerUser(user)

  -- Check to see if the module is already enabled.
  if not isRegisteredModule(module) then
    local addString = nil
    local ttlString = ""
    for _, mod in pairs(module:split("%.")) do
      if not addString then
        addString = mod
      else
        addString = string.format("%s.%s", addString, mod)
      end
      ttlString = string.format('%s"%s 1",', ttlString, addString)
    end
    ttlString = string.format("[%s]", ttlString:gsub("(.+),", "%1"))
    sendGMCP(string.format([[Core.Supports.Add %s ]], ttlString))
    registeredModules[module] = {}
  end

  -- Add the user to the module's user list.
  addUser(user, module)
end

-- Send the module list again on reconnect, so activated modules stay enabled during
--   a session unless explicitly disabled
function gmod.reenableModules()
  if not next(gmcp) then
    return
  end

  local list = {}
  for module, users in pairs(registeredModules) do
    list[#list + 1] = module .. " 1"
  end
  if list[1] then
    sendGMCP("Core.Supports.Add " .. yajl.to_string(list))
  end
end
registerAnonymousEventHandler("sysProtocolEnabled", function(_, protocol)
  if protocol == "GMCP" then
    gmod.reenableModules()
  end
end)

-- Remove a user from a module's user list. Disable the module if nobody is using it.
function disableModule(user, module)
  registerUser(user)

  -- Make sure the module is enabled in the first place
  if not isRegisteredModule(module) then
    return "no registered module"
  end

  dropUser(user, module)

  -- The user is now removed from the list. Check the user count.
  if getUserCount(module) < 1 then
    sendGMCP(string.format([[Core.Supports.Remove ["%s"] ]], module))
    registeredModules[module] = nil
  end
end

function printModules(user)
  -- If a user is specified, print the name of all associated modules.
  if user then
    if not registeredUsers[user] then
      print(string.format("<cyan>%s <white>is not a registered user.", user))
      return
    end
    cecho(string.format("\n\n<white>Module listing for user: <cyan>%s", user))
    cecho(string.format("\n<white>%s", string.rep("-", 45)))
    for i, v in pairs(registeredModules) do
      if v[user] then
        cecho(string.format("\n<yellow>%s", i))
      end
    end
    return
  end

  -- No user specified, print all existing Modules with a user list.
  print("Current modules:")
  for i, v in pairs(registeredModules) do
    cecho(string.format("\n<yellow>%s\n  ", i))
    local doComma = false
    for j, _ in pairs(v) do
      if not doComma then
        doComma = true
      else
        cecho("<white>, ")
      end
      cecho(string.format("<cyan>%s", j))
    end
  end
end
