Removed NPC and character parameters from NPC functions

These functions can only be used in the context of a character talking
to an NPC, so these parameters can be deduced from that context rather
than passing them explicitly all the time.

Simplifies NPC scripting.

11 files changed, 143 insertions, 139 deletions

diff --git a/example/scripts/maps/desert.lua b/example/scripts/maps/desert.lua
index 6b761dc..1fee2fc 100644
--- a/example/scripts/maps/desert.lua
+++ b/example/scripts/maps/desert.lua
@@ -39,7 +39,7 @@ end)
 function Smith(npc, ch, list)
     local sword_count = chr_inv_count(ch, true, true, "Sword")
     if sword_count > 0 then
-        npc_message(npc, ch, "Ah! I can see you already have a sword.")
+        npc_message("Ah! I can see you already have a sword.")
     end
     Merchant(npc, ch, list)
 end
@@ -54,7 +54,7 @@ function possessions_table(npc, ch)
             ..inventory_table[i].id..", "..inventory_table[i].name..", "
             ..inventory_table[i].amount
     end
-    npc_message(npc, ch, item_message)
+    npc_message(item_message)
 
     item_message = "Equipment:"..
                    "\nSlot id, item id, item name:"..
@@ -64,7 +64,7 @@ function possessions_table(npc, ch)
         item_message = item_message.."\n"..equipment_table[i].slot..", "
             ..equipment_table[i].id..", "..equipment_table[i].name
     end
-    npc_message(npc, ch, item_message)
+    npc_message(item_message)
 
 end
 
@@ -74,21 +74,21 @@ function Harmony(npc, ch, list)
     being_apply_status(ch, 1, 99999)
     -- Say all the messages in the messages list.
     for i = 1, #list do
-        npc_message(npc, ch, list[i])
+        npc_message(list[i])
     end
     --- Give the player 100 units of money the first time.
     if  harmony_have_talked_to_someone == false then
-        npc_message(npc, ch, "Here is some money for you to find some toys to play with.\nEh Eh!")
+        npc_message("Here is some money for you to find some toys to play with.\nEh Eh!")
         chr_money_change(ch, 100)
-        npc_message(npc, ch, string.format("You now have %d shiny coins!", chr_money(ch)))
+        npc_message(string.format("You now have %d shiny coins!", chr_money(ch)))
         harmony_have_talked_to_someone = true
-        npc_message(npc, ch, string.format("Try to come back with a better level than %i.", chr_get_level(ch)))
+        npc_message(string.format("Try to come back with a better level than %i.", chr_get_level(ch)))
     else
-        npc_message(npc, ch, "Let me see what you've got so far... Don't be afraid!")
+        npc_message("Let me see what you've got so far... Don't be afraid!")
         effect_create(EMOTE_WINK, npc)
         possessions_table(npc, ch)
     end
-    npc_message(npc, ch, "Have fun!")
+    npc_message("Have fun!")
     effect_create(EMOTE_HAPPY, npc)
     -- Make Harmony disappear for a while... with a small earthquake effect!
     local shakeX = posX(npc)
diff --git a/example/scripts/npcs/banker.lua b/example/scripts/npcs/banker.lua
index e6e1e28..88ba9ac 100644
--- a/example/scripts/npcs/banker.lua
+++ b/example/scripts/npcs/banker.lua
@@ -12,21 +12,21 @@
 
 function Banker(npc, ch)
     if being_get_gender(ch) == GENDER_MALE then
-        npc_message(npc, ch, "Welcome to the bank, sir!")
+        npc_message("Welcome to the bank, sir!")
     elseif being_get_gender(ch) == GENDER_FEMALE then
-        npc_message(npc, ch, "Welcome to the bank, madam!")
+        npc_message("Welcome to the bank, madam!")
     else
-        npc_message(npc, ch, "Welcome to the bank... uhm... person of unspecified gender!")
+        npc_message("Welcome to the bank... uhm... person of unspecified gender!")
     end
     local account = tonumber(chr_get_quest(ch, "BankAccount"))
     local result = -1
 
     if (account == nil) then --Initial account creation, if needed
-        npc_message(npc, ch, "Hello! Would you like to setup a bank account? There is a sign-on bonus right now!")
-        result = npc_choice(npc, ch, "Yes", "No")
+        npc_message("Hello! Would you like to setup a bank account? There is a sign-on bonus right now!")
+        result = npc_choice("Yes", "No")
         if (result == 1) then
             chr_set_quest(ch, "BankAccount", 5)
-            npc_message(npc, ch, "Your account has been made. Your sign-on bonus is 5GP.")
+            npc_message("Your account has been made. Your sign-on bonus is 5GP.")
             account = 5
         end
     end
@@ -37,41 +37,41 @@ function Banker(npc, ch)
         result = 1
         while (result < 3) do --While they've choosen a valid option that isn't "Never mind"
             account = tonumber(chr_get_quest(ch, "BankAccount")) --Why do I need to convert this?
-            npc_message(npc, ch, "Your balance: " .. account .. ".\nYour money: " .. chr_money(ch) .. ".")
-            result = npc_choice(npc, ch, "Deposit", "Withdraw", "Never mind")
+            npc_message("Your balance: " .. account .. ".\nYour money: " .. chr_money(ch) .. ".")
+            result = npc_choice("Deposit", "Withdraw", "Never mind")
             if (result == 1) then --Deposit
                 money = chr_money(ch);
                 if (money > 0) then --Make sure they have money to deposit
-                    npc_message(npc, ch, "How much would you like to deposit? (0 will cancel)")
-                    input = npc_ask_integer(npc, ch, 0, money, 1)
+                    npc_message("How much would you like to deposit? (0 will cancel)")
+                    input = npc_ask_integer(0, money, 1)
                     money = chr_money(ch)
                     if (input > 0 and input <= money) then --Make sure something weird doesn't happen and they try to deposit more than they have
                         chr_money_change(ch, -input)
                         chr_set_quest(ch, "BankAccount", account + input)
-                        npc_message(npc, ch, input .. " GP deposited.")
+                        npc_message(input .. " GP deposited.")
                     elseif (input > money) then --Chosen more than they have
-                        npc_message(npc, ch, "You don't have that much money. But you just did....")
+                        npc_message("You don't have that much money. But you just did....")
                     end
                 else
-                    npc_message(npc, ch, "You don't have any money to deposit!")
+                    npc_message("You don't have any money to deposit!")
                 end
             elseif (result == 2) then --Withdraw
                 if (account > 0) then --Make sure they have money to withdraw
-                    npc_message(npc, ch, "How much would you like to withdraw? (0 will cancel)")
-                    input = npc_ask_integer(npc, ch, 0, account, 1)
+                    npc_message("How much would you like to withdraw? (0 will cancel)")
+                    input = npc_ask_integer(0, account, 1)
                     if (input > 0 and input <= account) then --Make sure something weird doesn't happen and they try to withdraw more than they have
                         chr_money_change(ch, input)
                         chr_set_quest(ch, "BankAccount", account - input)
-                        npc_message(npc, ch, input .. " GP withdrawn.")
+                        npc_message(input .. " GP withdrawn.")
                     elseif (input > account) then --Chosen more than they have
-                        npc_message(npc, ch, "You don't have that much in your account. But you just did....")
+                        npc_message("You don't have that much in your account. But you just did....")
                     end
                 else
-                    npc_message(npc, ch, "Your account is empty!")
+                    npc_message("Your account is empty!")
                 end
             end
         end --This ends the while loop
     end
 
-    npc_message(npc, ch, "Thank you. Come again!")
+    npc_message("Thank you. Come again!")
 end
diff --git a/example/scripts/npcs/barber.lua b/example/scripts/npcs/barber.lua
index 70efb43..58aa1a9 100644
--- a/example/scripts/npcs/barber.lua
+++ b/example/scripts/npcs/barber.lua
@@ -79,11 +79,11 @@ function Barber(npc, ch, data)
 
     -- Choose an appropriate message
     if result == 1 then
-        npc_message(npc, ch, "Hello! What style would you like today?")
+        npc_message("Hello! What style would you like today?")
     elseif result == 2 then
-        npc_message(npc, ch, "Hello! What color would you like today?")
+        npc_message("Hello! What color would you like today?")
     else
-        npc_message(npc, ch, "Hello! What can I do for you today?")
+        npc_message("Hello! What can I do for you today?")
     end
 
     print("#styles ==", #styles)
@@ -91,7 +91,7 @@ function Barber(npc, ch, data)
     -- Repeat until the user selects nothing
     repeat
         if (result == 1) then -- Do styles
-            result = npc_choice(npc, ch, "Bald", styles, "Surprise me", "Never mind")
+            result = npc_choice("Bald", styles, "Surprise me", "Never mind")
 
             result = result -1
 
@@ -113,7 +113,7 @@ function Barber(npc, ch, data)
                 result = 3
             end
         elseif (result == 2) then -- Do colors
-            result = npc_choice(npc, ch, colors, "Surprise me", "Never mind")
+            result = npc_choice(colors, "Surprise me", "Never mind")
 
             --Random
             if (result == #colors + 1) then
@@ -130,10 +130,10 @@ function Barber(npc, ch, data)
 
         -- If we have both styles and colors, show the main menu
         if #styles > 0 and #colors > 0 then
-            result = npc_choice(npc, ch, "Change my style", "Change my color", "Never mind")
+            result = npc_choice("Change my style", "Change my color", "Never mind")
         end
     until result >= 3 --While they've choosen a valid option that isn't "Never mind"
 
     -- Let's close up
-    npc_message(npc, ch, "Thank you. Come again!")
+    npc_message("Thank you. Come again!")
 end
diff --git a/example/scripts/npcs/debugger.lua b/example/scripts/npcs/debugger.lua
index 621ba0f..e21982a 100644
--- a/example/scripts/npcs/debugger.lua
+++ b/example/scripts/npcs/debugger.lua
@@ -12,38 +12,38 @@
 
 function npc1_talk(npc, ch)
   on_remove(ch, function() print "Player has left the map." end);
-  npc_message(npc, ch, "Hello! I am the testing NPC.")
+  npc_message("Hello! I am the testing NPC.")
   local rights = chr_get_rights(ch);
 
   if (rights >= 128) then
-    npc_message(npc, ch, "Oh mighty server administrator, how can I avoid your wrath?")
+    npc_message("Oh mighty server administrator, how can I avoid your wrath?")
   elseif (rights >= 8) then
-    npc_message(npc, ch, "How can I be of assistance, sir gamemaster?")
+    npc_message("How can I be of assistance, sir gamemaster?")
   elseif (rights >= 4) then
-    npc_message(npc, ch, "What feature would you like to debug, developer?")
+    npc_message("What feature would you like to debug, developer?")
   elseif (rights >= 2) then
-    npc_message(npc, ch, "How can I assist you in your testing duties?")
+    npc_message("How can I assist you in your testing duties?")
   elseif (rights >= 1) then
-    npc_message(npc, ch, "What do you want, lowly player?")
+    npc_message("What do you want, lowly player?")
   else
-    npc_message(npc, ch, "...aren't you supposed to be banned??")
+    npc_message("...aren't you supposed to be banned??")
   end
 
-  local v = npc_choice(npc, ch, "Guns! Lots of guns!",
-                               "A Christmas party!",
-                               "To make a donation.",
-                               "Slowly count from one to ten.",
-                               "Tablepush Test")
+  local v = npc_choice("Guns! Lots of guns!",
+                       "A Christmas party!",
+                       "To make a donation.",
+                       "Slowly count from one to ten.",
+                       "Tablepush Test")
   if v == 1 then
-    npc_message(npc, ch, "Sorry, this is a heroic-fantasy game, I do not have any gun.")
+    npc_message("Sorry, this is a heroic-fantasy game, I do not have any gun.")
 
   elseif v == 2 then
     local n1, n2 = chr_inv_count(ch, 524, 511)
     if n1 == 0 or n2 ~= 0 then
-      npc_message(npc, ch, "Yeah right...")
+      npc_message("Yeah right...")
     else
-      npc_message(npc, ch, "I can't help you with the party. But I see you have a fancy hat. I could change it into Santa's hat. Not much of a party, but it would get you going.")
-      v = npc_choice(npc, ch, "Please do.", "No way! Fancy hats are classier.")
+      npc_message("I can't help you with the party. But I see you have a fancy hat. I could change it into Santa's hat. Not much of a party, but it would get you going.")
+      v = npc_choice("Please do.", "No way! Fancy hats are classier.")
       if v == 1 then
         chr_inv_change(ch, 524, -1, 511, 1)
       end
@@ -51,14 +51,14 @@ function npc1_talk(npc, ch)
 
   elseif v == 3 then
     if chr_money_change(ch, -100) then
-      npc_message(npc, ch, string.format("Thank you for you patronage! You are left with %d GP.", chr_money(ch)))
+      npc_message(string.format("Thank you for you patronage! You are left with %d GP.", chr_money(ch)))
       local g = tonumber(chr_get_quest(ch, "001_donation"))
       if not g then g = 0 end
       g = g + 100
       chr_set_quest(ch, "001_donation", g)
-      npc_message(npc, ch, string.format("As of today, you have donated %d GP.", g))
+      npc_message(string.format("As of today, you have donated %d GP.", g))
     else
-      npc_message(npc, ch, "I would feel bad taking money from someone that poor.")
+      npc_message("I would feel bad taking money from someone that poor.")
     end
 
   elseif v == 4 then
@@ -95,6 +95,6 @@ function npc1_talk(npc, ch)
     print("---------------");
   end
 
-  npc_message(npc, ch, "See you later!")
+  npc_message("See you later!")
 end
 
diff --git a/example/scripts/npcs/emotemaker.lua b/example/scripts/npcs/emotemaker.lua
index 0f54663..ee8928b 100644
--- a/example/scripts/npcs/emotemaker.lua
+++ b/example/scripts/npcs/emotemaker.lua
@@ -21,11 +21,10 @@ function emote_talk(npc, ch)
   elseif emo_state == EMOTE_HAPPY then
     state = "happy"
   end
-  npc_message(npc, ch, string.format("The emotional palm seems %s.", state))
-  v = npc_choice(npc, ch,
-    "Stupid palm, you are ugly and everyone hates you!",
-    "You are such a nice palm, let me give you a hug.",
-    "Are you a cocos nucifera or a syagrus romanzoffiana?")
+  npc_message(string.format("The emotional palm seems %s.", state))
+  v = npc_choice("Stupid palm, you are ugly and everyone hates you!",
+                 "You are such a nice palm, let me give you a hug.",
+                 "Are you a cocos nucifera or a syagrus romanzoffiana?")
 
   if (v     == 1) then
     emo_state = EMOTE_SAD
diff --git a/example/scripts/npcs/healer.lua b/example/scripts/npcs/healer.lua
index 3569673..910e221 100644
--- a/example/scripts/npcs/healer.lua
+++ b/example/scripts/npcs/healer.lua
@@ -5,8 +5,8 @@
 --]]
 
 function Healer(npc, ch)
-    npc_message(npc, ch, "Do you need healing?")
-    local c = npc_choice(npc, ch, "Heal me fully", "Heal 100 HP", "Don't heal me")
+    npc_message("Do you need healing?")
+    local c = npc_choice("Heal me fully", "Heal 100 HP", "Don't heal me")
     if c == 1 then
         being_heal(ch)
     elseif c == 2 then
diff --git a/example/scripts/npcs/merchant.lua b/example/scripts/npcs/merchant.lua
index 2ef0a6b..bcec5fa 100644
--- a/example/scripts/npcs/merchant.lua
+++ b/example/scripts/npcs/merchant.lua
@@ -12,9 +12,7 @@
 
 function Merchant(npc, ch, buy_sell_table)
 
-    local function say(message)
-        npc_message(npc, ch, message)
-    end
+    local say = npc_message
 
     -- Important note: You can add two tables made of trinoms here when calling the
     -- merchant function. E.g.: Merchant(npc, ch, buy_table, sell_table)
@@ -56,7 +54,7 @@ function Merchant(npc, ch, buy_sell_table)
     table.insert (choice_table, "Tell me about the objects on this map")
     table.insert (choice_table, "Nevermind...")
 
-    local v = npc_choice(npc, ch, choice_table)
+    local v = npc_choice(choice_table)
 
     --Debug and learning purpose
     --for i,k in ipairs(choice_table) do print(i,k) end
@@ -67,7 +65,7 @@ function Merchant(npc, ch, buy_sell_table)
 
     if v == 1 then
     -- "To buy."
-    local buycase = npc_trade(npc, ch, false, buy_sell_table[1])
+    local buycase = npc_trade(false, buy_sell_table[1])
     if buycase == 0 then
         say "What do you want to buy?"
     elseif buycase == 1 then
@@ -80,7 +78,7 @@ function Merchant(npc, ch, buy_sell_table)
 
         if buy_sell_table[2] == nil then
             -- "To sell stuff..."
-            local sellcase = npc_trade(npc, ch, true)
+            local sellcase = npc_trade(true)
             if sellcase == 0 then
                 say "Ok, what do you want to sell?"
             elseif sellcase == 1 then
@@ -90,7 +88,7 @@ function Merchant(npc, ch, buy_sell_table)
             end
         else
             -- "Can you make me a price for what I have?"
-            local sellcase = npc_trade(npc, ch, true, buy_sell_table[2])
+            local sellcase = npc_trade(true, buy_sell_table[2])
             if sellcase == 0 then
                 say "Here we go:"
             elseif sellcase == 1 then
diff --git a/example/scripts/npcs/postman.lua b/example/scripts/npcs/postman.lua
index 95e6844..c0901f8 100644
--- a/example/scripts/npcs/postman.lua
+++ b/example/scripts/npcs/postman.lua
@@ -11,17 +11,17 @@
 ----------------------------------------------------------------------------------
 
 function post_talk(npc, ch)
-  npc_message(npc, ch, "Hello " .. being_get_name(ch))
+  npc_message("Hello " .. being_get_name(ch))
   local strength = being_get_attribute(ch, ATTR_STRENGTH)
-  npc_message(npc, ch, "You have " .. tostring(strength) .. " strength")
-  npc_message(npc, ch, "What would you like to do?")
-  local answer = npc_choice(npc, ch, "View Mail", "Send Mail", "Nothing")
+  npc_message("You have " .. tostring(strength) .. " strength")
+  npc_message("What would you like to do?")
+  local answer = npc_choice("View Mail", "Send Mail", "Nothing")
   if answer == 1 then
     local sender, post = chr_get_post(ch)
     if sender == "" then
-      npc_message(npc, ch, "No Post right now, sorry")
+      npc_message("No Post right now, sorry")
     else
-      npc_message(npc, ch, tostring(sender) .. " sent you " .. tostring(post))
+      npc_message(tostring(sender) .. " sent you " .. tostring(post))
     end
   end
   if answer == 2 then
diff --git a/src/game-server/npc.cpp b/src/game-server/npc.cpp
index b5e17ea..980358d 100644
--- a/src/game-server/npc.cpp
+++ b/src/game-server/npc.cpp
@@ -94,6 +94,8 @@ void Npc::start(Entity *npc, Entity *ch)
     {
         Script::Thread *thread = script->newThread();
         thread->getContext().map = npc->getMap();
+        thread->getContext().npc = npc;
+        thread->getContext().character = ch;
         script->prepare(talkCallback);
         script->push(npc);
         script->push(ch);
diff --git a/src/scripting/lua.cpp b/src/scripting/lua.cpp
index 2d9692b..37d1832 100644
--- a/src/scripting/lua.cpp
+++ b/src/scripting/lua.cpp
@@ -493,32 +493,34 @@ static int item_drop(lua_State *s)
  */
 
 /** LUA npc_message (input)
- * npc_message(handle npc, handle character, string message)
+ * npc_message(string message)
  **
  * **Warning:** May only be called from an NPC talk function.
  *
- * Shows an NPC dialog box on the screen of character ''ch'' displaying the
- * string ''msg''. Idles the current thread until the user click "OK".
+ * Shows an NPC dialog box on the screen of displaying the string ''msg''.
+ * Idles the current thread until the user click "OK".
  */
 static int npc_message(lua_State *s)
 {
-    Entity *npc = checkNpc(s, 1);
-    Entity *q = checkCharacter(s, 2);
-    const char *m = luaL_checkstring(s, 3);
+    const char *m = luaL_checkstring(s, 1);
 
     Script::Thread *thread = checkCurrentThread(s);
+    Entity *npc = thread->getContext().npc;
+    Entity *character = thread->getContext().character;
+    if (!(npc && character))
+        luaL_error(s, "not in npc conversation");
 
     MessageOut msg(GPMSG_NPC_MESSAGE);
     msg.writeInt16(npc->getComponent<ActorComponent>()->getPublicID());
     msg.writeString(m);
-    gameHandler->sendTo(q, msg);
+    gameHandler->sendTo(character, msg);
 
     thread->mState = Script::ThreadPaused;
     return lua_yield(s, 0);
 }
 
 /** LUA npc_choice (input)
- * npc_choice(handle npc, handle character, item1, item2, ... itemN)
+ * npc_choice(item1, item2, ... itemN)
  **
  * **Return value:** Number of the option the player selected (starting with 1).
  *
@@ -526,23 +528,24 @@ static int npc_message(lua_State *s)
  *
  * Shows an NPC dialog box on the users screen with a number of dialog options
  * to choose from. Idles the current thread until the user selects one or
- * aborts the current   thread when the user clicks "cancel".
+ * aborts the current thread when the user clicks "cancel".
  *
  * Items are either strings or tables of strings (indices are ignored,
  * but presumed to be taken in order). So,
- * ''npc_choice(npc, ch, "A", {"B", "C", "D"}, "E")'' is the same as
- * ''npc_choice(npc, ch, "A", "B", "C", "D", "E")''.
+ * ''npc_choice("A", {"B", "C", "D"}, "E")'' is the same as
+ * ''npc_choice("A", "B", "C", "D", "E")''.
  */
 static int npc_choice(lua_State *s)
 {
-    Entity *npc = checkNpc(s, 1);
-    Entity *q = checkCharacter(s, 2);
-
     Script::Thread *thread = checkCurrentThread(s);
+    Entity *npc = thread->getContext().npc;
+    Entity *character = thread->getContext().character;
+    if (!(npc && character))
+        luaL_error(s, "not in npc conversation");
 
     MessageOut msg(GPMSG_NPC_CHOICE);
     msg.writeInt16(npc->getComponent<ActorComponent>()->getPublicID());
-    for (int i = 3, i_end = lua_gettop(s); i <= i_end; ++i)
+    for (int i = 1, i_end = lua_gettop(s); i <= i_end; ++i)
     {
         if (lua_isstring(s, i))
         {
@@ -572,14 +575,14 @@ static int npc_choice(lua_State *s)
             return 0;
         }
     }
-    gameHandler->sendTo(q, msg);
+    gameHandler->sendTo(character, msg);
 
     thread->mState = Script::ThreadExpectingNumber;
     return lua_yield(s, 0);
 }
 
 /** LUA npc_ask_integer (input)
- * npc_ask_integer(handle npc, handle character, min_num, max_num, [default_num])
+ * npc_ask_integer(min_num, max_num, [default_num])
  **
  * **Return value:** The number the player entered into the field.
  *
@@ -591,27 +594,29 @@ static int npc_choice(lua_State *s)
  */
 static int npc_ask_integer(lua_State *s)
 {
-    Entity *npc = checkNpc(s, 1);
-    Entity *q = checkCharacter(s, 2);
-    int min = luaL_checkint(s, 3);
-    int max = luaL_checkint(s, 4);
-    int defaultValue = luaL_optint(s, 5, min);
+    int min = luaL_checkint(s, 1);
+    int max = luaL_checkint(s, 2);
+    int defaultValue = luaL_optint(s, 3, min);
 
     Script::Thread *thread = checkCurrentThread(s);
+    Entity *npc = thread->getContext().npc;
+    Entity *character = thread->getContext().character;
+    if (!(npc && character))
+        luaL_error(s, "not in npc conversation");
 
     MessageOut msg(GPMSG_NPC_NUMBER);
     msg.writeInt16(npc->getComponent<ActorComponent>()->getPublicID());
     msg.writeInt32(min);
     msg.writeInt32(max);
     msg.writeInt32(defaultValue);
-    gameHandler->sendTo(q, msg);
+    gameHandler->sendTo(character, msg);
 
     thread->mState = Script::ThreadExpectingNumber;
     return lua_yield(s, 0);
 }
 
 /** LUA npc_ask_string (input)
- * npc_ask_string(handle npc, handle character)
+ * npc_ask_string()
  **
  * **Return value:** The string the player entered.
  *
@@ -621,32 +626,34 @@ static int npc_ask_integer(lua_State *s)
  */
 static int npc_ask_string(lua_State *s)
 {
-    Entity *npc = checkNpc(s, 1);
-    Entity *q = checkCharacter(s, 2);
-
     Script::Thread *thread = checkCurrentThread(s);
+    Entity *npc = thread->getContext().npc;
+    Entity *character = thread->getContext().character;
+    if (!(npc && character))
+        luaL_error(s, "not in npc conversation");
 
     MessageOut msg(GPMSG_NPC_STRING);
     msg.writeInt16(npc->getComponent<ActorComponent>()->getPublicID());
-    gameHandler->sendTo(q, msg);
+    gameHandler->sendTo(character, msg);
 
     thread->mState = Script::ThreadExpectingString;
     return lua_yield(s, 0);
 }
 
 /** LUA npc_post (input)
- * npc_post(handle npc, handle character)
+ * npc_post()
  **
  * Starts retrieving post. Better not try to use it so far.
  */
 static int npc_post(lua_State *s)
 {
-    Entity *npc = checkNpc(s, 1);
-    Entity *q = checkCharacter(s, 2);
+    const Script::Context *context = getScript(s)->getContext();
+    Entity *npc = context->npc;
+    Entity *character = context->character;
 
     MessageOut msg(GPMSG_NPC_POST);
     msg.writeInt16(npc->getComponent<ActorComponent>()->getPublicID());
-    gameHandler->sendTo(q, msg);
+    gameHandler->sendTo(character, msg);
 
     return 0;
 }
@@ -704,19 +711,15 @@ static int announce(lua_State *s)
  */
 
 /** LUA npc_trade (inventory)
- * npc_trade(handle npc,
- *           handle character,
- *           bool mode,
+ * npc_trade(bool mode,
  *           {int item1id, int item1amount, int item1cost}, ...,
  *           {int itemNid, int itemNamount, int itemNcost})
- * npc_trade(handle npc,
- *           handle character,
- *           bool mode,
+ * npc_trade(bool mode,
  *           {string item1name, int item1amount, int item1cost}, ...,
  *           {string itemNname, int itemNamount, int itemNcost})
  **
  * FIXME: Move into a seperate file
- * Opens a trade window for ''character'' while talking with ''npc''. ''mode''
+ * Opens a trade window from an NPC conversation. ''mode''
  * is true for selling and false for buying. You have to set each items the NPC
  * is buying/selling,    the cost and the maximum amount in {}.
  *
@@ -735,24 +738,24 @@ static int announce(lua_State *s)
  * **Examples:**
  * <code lua npc_trade.lua>
  *     -- "A buy sample."
- *     local buycase = npc_trade(npc, ch, false, {
+ *     local buycase = npc_trade(false, {
  *         {"Sword", 10, 20},
  *         {"Bow", 10, 30},
  *         {"Dagger", 10, 50}
  *     })
  *     if buycase == 0 then
- *       npc_message(npc, ch, "What do you want to buy?")
+ *       npc_message("What do you want to buy?")
  *     elseif buycase == 1 then
- *       npc_message(npc, ch, "I've got no items to sell.")
+ *       npc_message("I've got no items to sell.")
  *     else
- *       npc_message(npc, ch, "Hmm, something went wrong... Ask a scripter to
+ *       npc_message("Hmm, something went wrong... Ask a scripter to
  *       fix the buying mode!")
  *     end
  *
  * -- ...
  *
  *    -- "Example: Let the player sell only pre-determined items."
- *    local sellcase = npc_trade(npc, ch, true, {
+ *    local sellcase = npc_trade(true, {
  *                      {"Sword", 10, 20},
  *                      {"Bow", 10, 30},
  *                      {"Dagger", 10, 200},
@@ -761,42 +764,40 @@ static int announce(lua_State *s)
  *                      {"Cactus Drink", 10, 25}
  *     })
  *     if sellcase == 0 then
- *       npc_message(npc, ch, "Here we go:")
+ *       npc_message("Here we go:")
  *     elseif sellcase == 1 then
- *       npc_message(npc, ch, "I'm not interested by your items.")
+ *       npc_message("I'm not interested by your items.")
  *     else
- *       npc_message(npc, ch, "Hmm, something went wrong...")
- *       npc_message(npc, ch, "Ask a scripter to fix me!")
+ *       npc_message("Hmm, something went wrong...")
+ *       npc_message("Ask a scripter to fix me!")
  *     end
  *
  * -- ...
  *
  *     -- "Example: Let the player sell every item with a 'value' parameter in
  *     the server's items.xml file
- *     local sellcase = npc_trade(npc, ch, true)
+ *     local sellcase = npc_trade(true)
  *     if sellcase == 0 then
- *       npc_message(npc, ch, "Ok, what do you want to sell:")
+ *       npc_message("Ok, what do you want to sell:")
  *     elseif sellcase == 1 then
- *       npc_message(npc, ch, "I'm not interested by any of your items.")
+ *       npc_message("I'm not interested by any of your items.")
  *     else
- *       npc_message(npc, ch, "Hmm, something went wrong...")
- *       npc_message(npc, ch, "Ask a scripter to fix me!")
+ *       npc_message("Hmm, something went wrong...")
+ *       npc_message("Ask a scripter to fix me!")
  *     end
  * </code>
  */
 static int npc_trade(lua_State *s)
 {
-    Entity *npc = checkNpc(s, 1);
-    Entity *q = checkCharacter(s, 2);
-    if (!lua_isboolean(s, 3))
-    {
-        luaL_error(s, "npc_trade called with incorrect parameters.");
-        return 0;
-    }
+    const Script::Context *context = getScript(s)->getContext();
+    Entity *npc = context->npc;
+    Entity *character = context->character;
+
+    luaL_argcheck(s, lua_isboolean(s, 1), 1, "boolean expected");
+    bool sellMode = lua_toboolean(s, 1);
 
-    bool sellMode = lua_toboolean(s, 3);
-    BuySell *t = new BuySell(q, sellMode);
-    if (!lua_istable(s, 4))
+    BuySell *t = new BuySell(character, sellMode);
+    if (!lua_istable(s, 2))
     {
         if (sellMode)
         {
@@ -833,7 +834,7 @@ static int npc_trade(lua_State *s)
     int nbItems = 0;
 
     lua_pushnil(s);
-    while (lua_next(s, 4))
+    while (lua_next(s, 2))
     {
         if (!lua_istable(s, -1))
         {
diff --git a/src/scripting/script.h b/src/scripting/script.h
index 694deed..7cf457c 100644
--- a/src/scripting/script.h
+++ b/src/scripting/script.h
@@ -43,9 +43,13 @@ class Script : public sigc::trackable
         struct Context
         {
             MapComposite *map;
+            Entity *npc;
+            Entity *character;
 
             Context()
                 : map(0)
+                , npc(0)
+                , character(0)
             {}
         };