--[[nef_20230424   CITY_STEAL

The function stolen can be used to keep track of cities that have had tech stolen by a diplomat.

Arguments:
1. City.
 a. nil (default).  List cities that have had a tech stolen (and by whom).
 b. boolean false.  Delete all current 'stolen' records(with 2b.).  (Dubious use.)
 c. userdata or a featured text string defining a City. 
2. Action to be taken:
 a. nil (default).  Show current state of the City.
 b. Boolean false.  Mark the City as having had no tech stolen . (Not recommended.)
 c. Anything else.  Mark the City as having had tech stolen.  (Not recommended.)
 
To delete the list both arguments need to be boolean false.

The module should be loaded into an autoscript to start recording without any delays. 

Requires FEATURED_TEXT, PARSER, and SUPPORT_continuity.
]]
if signal then  -- CITY_STEAL
-- SOH   
   local featured = setmetatable({},{  -- FEATURED_TEXT
     __index = function(t,k) local ft = assert(log.featured, 'Featured text not loaded')
       return assert(ft[k], 'Featured '..k..' not loaded.'  ) end;}) 
   local function link  (...) link  = featured.link;  return link  (...) end
   local function bbcode(...) 
                bbcode       = featured.bbcode; return bbcode      (...) end
                
   local SP       = setmetatable({},{  -- SUPPORT_basic
     __index = function(t,k) local SP = assert(game.SP, 'Support package not loaded')
       return assert(SP[k], 'Support '..k..' not loaded.') end;}) 
   local function user  (...) user   = SP.user;       return user  (...) end
   local function colored_link(...) 
                colored_link = SP.colored_link; return colored_link(...) end
-- SUPPORT_extended
   local function get_link_bb(...)
                get_link_bb  = SP.get_link_bb;  return get_link_bb (...) end
-- SUPPORT_continuity
   local function tables(...) tables = SP.tables;     return tables(...) end
   local MTs = setmetatable({},
     {__newindex = function(t,k,v) rawset(t,k,v); v._fc_keep = true end})
   local get = setmetatable({}, {
    __index = function(t,k) t[k] = tables(k, MTs) return t[k] end;
    __call  = function(t,k) t[k] = tables(k)      return t[k] end;
                                })
-- STX
   local reporter  = function(tile,msg,...) notify.event(user(),tile,msg,...) end 
   local report    = function(tile,...) reporter(tile,E.BROADCAST_REPORT,...) end
  
   MTs.stolen = {__call = function (t,k) return t[k] and '' or 'NOT ' end;}

   function stolen (object, option); object = get_link_bb(object)
     local stolen = get.stolen 
     if false then
     elseif tolua.type(object) == 'City' then
       if option ~= nil then watch(stolen, object, option and user() or nil) end
       report(object.tile,'Tech %s stolen from %s',stolen(object),colored_link(object))
     elseif object == nil  then
       local r_player = type (option) == 'number' and find.player(option)
       local function p_report(...); p_report = report
         p_report(nil, bbcode ("b","Tech stolen cities.")..
                       ((' %s'):format (r_player or ''))); 
         p_report(...)
             end
       for object, player in pairs (stolen) do
         if object:exists() and not r_player or r_player == player
         then p_report(object.tile, colored_link(object)..
                  (' %s'):format (not r_player and player or ''))
         end
       end; if p_report ~= report then report(nil, "No tech stolen cities") end
     elseif object == false and option == false then get 'stolen'
     else report(nil, 'Argument not a city reference') end
   end

   do_signals     = function (signals, active)
      local signal = signal [active and 'replace' or 'remove']
      for Signal, callback in pairs(signals) do signal(Signal, callback) end
      return active end
   local CBs           = setmetatable({
      city_destroyed           = '.tech_steal_dies';    -- 10
      action_started_unit_city = '.tech_steal_action';  -- 20	
                },{ __call = do_signals})              
   local CB_research   = setmetatable({                
      tech_researched          = '.tech_steal_city';    --  9
                },{ __call = do_signals})              
   local CB_unit_steal = setmetatable({                
      unit_lost                = '.tech_steal_unit';    -- 14  
                },{ __call = do_signals})

   do  -- startup   
       CBs(true)
   end
   
   do -- callbacks
    local tech_unit, tech_city
   
-- 10	city_destroyed            (City, Player (loser), Player (destroyer))
    _ENV[CBs.city_destroyed] = function (city); get.stolen[city] = nil; end
    
-- 20	action_started_unit_city  (string (Action rule_name), Unit (actor), City (target))	
    _ENV[CBs.action_started_unit_city] = function (action, unit, city)
      if   CB_research(action:rule_name()=='Steal Tech')
      then tech_unit, tech_city  = unit, city;
      end                                end
    
-- 9	tech_researched	       (Tech_Type, Player, string) 
    _ENV[CB_research.tech_researched]  = function (Tech_Type, winner, reason)
      CB_research(false)
      CB_unit_steal(reason == "stolen" and tech_unit.owner == winner) 
                                         end;

-- 14	unit_lost              (Unit, Player (loser), string)
    _ENV[CB_unit_steal.unit_lost]      = function (unit, loser, reason)
        CB_unit_steal(false)
        if   reason == "used" and  tech_unit == unit
        then get.stolen[tech_city] = loser
             -- notify.embassies (tech_city.owner, tech_city.tile, E.BROADCAST_REPORT,
               -- '%s %s %s %s' ..
               -- ' %s %s',
               -- colored_link(tech_city), reason, game.turn(), unit.owner,
               -- tech_unit, unit,
               -- nil) 
        end                              end
   end
--ETX
end
--------       end CITY_STEAL