#! /usr/bin/lua

-- by Michael Anderson at
-- https://stackoverflow.com/questions/8722620/comparing-two-index-tables-by-index-value-in-lua
-- modified by Roger
function recursive_compare(t1,t2)
  -- Use usual comparison first.
  if t1==t2 then return true end
  -- We only support non-default behavior for tables
  if (type(t1)~="table") then return false end
  -- They better have the same metatables
  local mt1 = getmetatable(t1)
  local mt2 = getmetatable(t2)
  if( not recursive_compare(mt1,mt2) ) then return false end
  -- Build list of all keys
  local kk = {}
  for k1, _ in pairs(t1) do
     kk[k1] = true
  end
  for k2, _ in pairs(t2) do
     kk[k2] = true
  end
  -- Check each key that exists in at least one table
  for _, k in ipairs(kk) do
     if (not recursive_compare(t1[k], t2[k])) then
        return false
     end
  end
  return true
end

function mergeitems(a, b)
   local c = {}
   for i, v in ipairs({a, b}) do
      for j, w in ipairs(v) do
         if c[w[1]] == nil then
            c[w[1]] = 0
         end
         c[w[1]] = c[w[1]] + w[2]
      end
   end
   local k = {}
   for t, _ in pairs(c) do
      table.insert(k, t)
   end
   table.sort(k)
   local out = {}
   for _, i in ipairs(k) do
      table.insert(out, {i, c[i]})
   end
   return out
end

if recursive_compare(mergeitems({{1, 1}, {2, 1}, {3, 2}}, {{2, 2}, {1, 3}}), {{1, 4}, {2, 3}, {3, 2}}) then
  io.write("Pass")
else
  io.write("FAIL")
end
io.write(" ")

if recursive_compare(mergeitems({{1, 2}, {2, 3}, {1, 3}, {3, 2}}, {{3, 1}, {1, 3}}), {{1, 8}, {2, 3}, {3, 3}}) then
  io.write("Pass")
else
  io.write("FAIL")
end
io.write(" ")

if recursive_compare(mergeitems({{1, 1}, {2, 2}, {3, 3}}, {{2, 3}, {2, 4}}), {{1, 1}, {2, 9}, {3, 3}}) then
  io.write("Pass")
else
  io.write("FAIL")
end
print("")