implemented some of the effects

README.md

@@ -29,6 +29,10 @@ There are two ways:
    NPC you want to change. This is much more powerful. Lua code can be
    entered and later executed by the NPC.
 
+Hint: The command "/npc_talk_debug <npc_id>" allows you to get debug
+      information regarding preconditions and effects. You can turn it
+      off with "/npc_talk_debug off". The NPC ID can be seen in the
+      setup dialog for preconditions and effects.
 
 The privs
 =========

fs_edit_effects.lua

@@ -27,6 +27,9 @@
 -- on_failure:
 -- 	r_value		alternate target dialog if the action failed
 --
+-- chat_all:
+-- 	r_value		chat message sent to all players
+--
 -- Unlike in preconditions, trade (the trade action already happened) and
 -- inventory actions are not supported as effects.
 --
@@ -152,6 +155,138 @@ yl_speak_up.show_effect = function(r)
 end
 
 
+-- executes an effect/result r for the player and npc n_id;
+-- returns true on success (relevant for on_failure)
+-- TODO: in edit mode, nothing gets executed except perhaps dialog
+yl_speak_up.execute_effect = function(player, n_id, o_id, r)
+	if(not(r.r_type) or r.r_type == "") then
+                -- nothing to do
+                return true
+	elseif(r.r_type == "auto" or r.r_type == "trade") then
+		-- these effects don't do anything
+		return true
+	elseif(r.r_type == "dialog") then
+		-- TODO: how to handle target dialog?
+		return true
+	elseif(r.r_type == "function") then
+		return yl_speak_up.eval_and_execute_function(player, r, "r_")
+	elseif(r.r_type == "give_item") then
+		if(not(v.r_value)) then
+			return false
+		end
+		local item = ItemStack(v.r_value)
+		if(not(minetest.registered_items[item:get_name()])) then
+			yl_speak_up.debug_msg(player, n_id, o_id, tostring(r_id).." "..
+				"give_item: "..tostring(item:get_name()).." unknown.")
+			return false
+		end
+		local r = player:get_inventory():add_item("main", item)
+		if(not(r)) then
+			yl_speak_up.debug_msg(player, n_id, o_id, tostring(r_id).." "..
+				"give_item: "..tostring(item:get_name()).." failed.")
+			return false
+		end
+		return true
+	elseif(r.r_type == "take_item") then
+		if(not(v.r_value)) then
+			return false
+		end
+		local item = ItemStack(v.r_value)
+		if(not(minetest.registered_items[item:get_name()])) then
+			yl_speak_up.debug_msg(player, n_id, o_id, tostring(r_id).." "..
+				"take_item: "..tostring(item:get_name()).." unknown.")
+			return false
+		end
+		local r = player:get_inventory():remove_item("main", item)
+		if(not(r)) then
+			yl_speak_up.debug_msg(player, n_id, o_id, tostring(r_id).." "..
+				"take_item: "..tostring(item:get_name()).." failed.")
+			return false
+		end
+		return true
+	elseif(r.r_type == "move") then
+		-- TODO: copy/adjust effect "move"
+	-- "an internal state (i.e. of a quest)", -- 2
+	elseif(r.r_type == "state") then
+		-- TODO: implement effect "state"
+	-- "a block somewhere" -- 3
+	elseif(r.r_type == "block") then
+		-- TODO: implement effect "block"
+	-- ""NPC crafts soemthing", -- 4
+	elseif(r.r_type == "craft") then
+		if(not(r.r_craft_grid) or not(r.r_value)) then
+			return false
+		end
+		local input = {}
+		input.items = {}
+		-- multiple slots in the craft grid may contain the same item
+		local sum_up = {}
+		for i, v in ipairs(r.r_craft_grid) do
+			if(v and v ~= "") then
+				local stack = ItemStack(v)
+				-- store this for later crafting
+				input.items[ i ] = stack
+				local name = stack:get_name()
+				if(sum_up[ name ]) then
+					sum_up[ name ] = sum_up[ name ] + stack:get_count()
+				else
+					sum_up[ name ] = stack:get_count()
+				end
+			else
+				-- empty itemstack in this slot
+				input.items[ i ] = ItemStack("")
+			end
+		end
+		-- does the NPC have all these items in his inventory?
+		local npc_inv = minetest.get_inventory({type="detached",
+					name="yl_speak_up_npc_"..tostring(n_id)})
+		for k, v in pairs(sum_up) do
+                        if(not(npc_inv:contains_item("npc_main", k.." "..v))) then
+				yl_speak_up.debug_msg(player, n_id, o_id, tostring(r_id).." "..
+					"Crafting failed: NPC does not have "..tostring(k.." "..v))
+				return false
+			end
+		end
+		-- do these input items form a valid craft recipe?
+		input.method = "normal" -- normal crafting; no cooking or fuel or the like
+		input.width = 3
+		local output, decremented_input = minetest.get_craft_result(input)
+		if(output.item:is_empty()) then
+			yl_speak_up.debug_msg(player, n_id, o_id, tostring(r_id).." "..
+				"Crafting failed: No output for that recipe.")
+			return false
+		end
+		-- the craft receipe may have changed in the meantime and yield a diffrent result
+		local expected_stack = ItemStack(r.r_value)
+		if(output.item:get_name() ~= expected_stack:get_name()
+		  or output.item:get_count() ~= expected_stack:get_count()) then
+			yl_speak_up.debug_msg(player, n_id, o_id, tostring(r_id).." "..
+				"Crafting failed: Diffrent output: "..tostring(output.item:to_string()))
+			return false
+		end
+		-- TODO: actually consume the items required, return the ones in decremented_input
+		yl_speak_up.debug_msg(player, n_id, o_id, tostring(r_id).." "..
+				"Great: Crafting is possible!")
+		return true
+	-- "go to other dialog if the action (i.e. trade) failed", -- 5
+	elseif(r.r_type == "on_failure") then
+		-- TODO: implement effect on_failure
+	-- "send a chat message to all players", -- 6
+	elseif(r.r_type == "chat_all") then
+		local pname = player:get_player_name()
+		local dialog = yl_speak_up.speak_to[pname].dialog
+		local text = r.r_value
+		-- replace $NPC_NAME$, $OWNER_NAME$, $PLAYER_NAME$ etc.
+		text = yl_speak_up.replace_vars_in_text(text, dialog, pname)
+		minetest.chat_send_all(text)
+		-- sending a chat message always counts as successful
+		return true
+	end
+	-- fallback: unkown type
+	return false
+end
+
+
 -- these are only wrapper functions for those in fs_edit_general.lua
 
 yl_speak_up.input_fs_edit_effects = function(player, formname, fields)