ADD - introduce unique phone devices

sky_phone/source/shared/imei.lua

@@ -0,0 +1,47 @@
+SkyPhoneImei = {}
+
+function SkyPhoneImei.CheckDigit(body)
+    if type(body) ~= "string" or not body:match("^%d%d%d%d%d%d%d%d%d%d%d%d%d%d$") then
+        return nil
+    end
+
+    local sum = 0
+    for index = 1, 14 do
+        local digit = tonumber(body:sub(index, index))
+        if index % 2 == 0 then
+            digit = digit * 2
+            if digit > 9 then
+                digit = digit - 9
+            end
+        end
+        sum = sum + digit
+    end
+    return tostring((10 - (sum % 10)) % 10)
+end
+
+function SkyPhoneImei.FromEntropy(entropy)
+    if type(entropy) ~= "string" then
+        return nil
+    end
+
+    local digits = {}
+    for character in entropy:lower():gmatch("[0-9a-f]") do
+        digits[#digits + 1] = tostring(tonumber(character, 16) % 10)
+        if #digits == 14 then
+            break
+        end
+    end
+    if #digits ~= 14 then
+        return nil
+    end
+
+    local body = table.concat(digits)
+    return body .. SkyPhoneImei.CheckDigit(body)
+end
+
+function SkyPhoneImei.IsValid(value)
+    if type(value) ~= "string" or not value:match("^%d%d%d%d%d%d%d%d%d%d%d%d%d%d%d$") then
+        return false
+    end
+    return value:sub(15, 15) == SkyPhoneImei.CheckDigit(value:sub(1, 14))
+end