Update to work with the new exchange rate system.

README.md

@@ -16,7 +16,9 @@ spaces.
 
 The following lurkcoin-specific functions and variables exist:
 
- - `lurkcoin.exchange_rate`: The exchange rate, *do not modify this!*
+ - `lurkcoin.exchange_rate`: The raw exchange rate, *do not modify this!*
+ - `lurkcoin.get_exchange_rate(amount, to, callback)`: Get an exchange rate
+    from this server.
  - `lurkcoin.pay(from, to, server, amount, callback)`: Makes `from` pay someone
     `amount`cr, and calls `callback` on success/faliure. `callback` should have two
     parameters, `success` and `msg`.

atm-core.lua

@@ -52,7 +52,7 @@ end
 local withdrawls = false
 
 -- Payment screen
-function formspecs.pay(name, fields)
+function formspecs.pay(name, fields, guessed_amount)
     fields = fields or {}
     local formspec =
         'field[0.8,3.5;7,1;user;User to pay;' .. e(fields.user or '') .. ']' ..
@@ -73,10 +73,28 @@ function formspecs.pay(name, fields)
         formspec = formspec ..
             'label[0.5,7;Please confirm the above values.'
         if fields.server ~= lurkcoin.server_name then
-            local r = (tonumber(fields.amount) or 0) / lurkcoin.exchange_rate
-            r = tostring(math.floor(r * 100) / 100)
-            formspec = formspec ..
-                '\n' .. fields.amount .. 'cr is equal to \xc2\xa4' .. r .. '.'
+            local exc = -1
+            if type(fields._exchange_rate) == 'number' then
+                exc = fields._exchange_rate
+            end
+
+            if exc < 0 then
+                lurkcoin.get_exchange_rate(fields.amount, fields.server or
+                        lurkcoin.server_name, function(data)
+                    print('Exchange rate callback with data ' .. tostring(data))
+                    if not data then
+                        fields._err = 'That server does not exist!'
+                    end
+                    fields._exchange_rate = data
+                    return lurkcoin.show_atm(name, 'pay', fields)
+                end)
+                return formspec .. '\n' .. fields.amount .. 'cr is equal to' ..
+                    ' ...\n\n(Calculating...)]'
+            end
+
+            exc = tostring(math.floor(exc * 100) / 100)
+            formspec = formspec .. '\n' .. fields.amount .. 'cr is ' ..
+                'equal to \xc2\xa4' .. exc .. '.'
         end
         formspec = formspec .. ']' ..
             'button[0.5,8;3.5,1;payuser;Cancel]' ..

core.lua

@@ -130,6 +130,25 @@ end
 -- Start syncing once the game is loaded.
 minetest.after(0, sync)
 
+-- Get an exchange rate
+function lurkcoin.get_exchange_rate(amount, to, callback)
+    assert(callback)
+    amount = amount and tonumber(amount)
+    if not amount or amount ~= amount then return callback(nil) end
+
+    get('exchange_rates', {
+        from    = lurkcoin.server_name,
+        to      = to or 'lurkcoin',
+        amount  = tostring(amount),
+    }, function(res)
+        if res.code == 200 then
+            local amount = tonumber(res.data)
+            if amount == amount then return callback(amount) end
+        end
+        return callback(nil)
+    end)
+end
+
 -- Pay a user (cross-server)
 function lurkcoin.pay(from, to, server, amount, callback)
     assert(type(amount) == 'number' and callback)
@@ -159,7 +178,8 @@ function lurkcoin.pay(from, to, server, amount, callback)
     return get('pay', {
         target = to,
         server = server,
-        amount = tostring(amount / lurkcoin.exchange_rate)
+        amount = tostring(amount),
+        local_currency = 'true'
     }, function(res)
         if res.code ~= 200 then
             lurkcoin.bank.add(from, amount, 'Reverting failed transaction.')