Handle duplicate pings received by gps.locate

Co-authored-by: Wojbie <Wojbie@gmail.com>

projects/core/src/main/resources/data/computercraft/lua/rom/apis/gps.lua

@@ -157,12 +157,22 @@ function locate(_nTimeout, _bDebug)
                     if tFix.nDistance == 0 then
                         pos1, pos2 = tFix.vPosition, nil
                     else
-                        table.insert(tFixes, tFix)
+                        -- Insert our new position in our table, with a maximum of three items. If this is close to a
+                        -- previous position, replace that instead of inserting.
+                        local insIndex = math.min(3, #tFixes + 1)
+                        for i, older in pairs(tFixes) do
+                            if (older.vPosition - tFix.vPosition):length() < 5 then
+                                insIndex = i
+                                break
+                            end
+                        end
+                        tFixes[insIndex] = tFix
+
                         if #tFixes >= 3 then
                             if not pos1 then
-                                pos1, pos2 = trilaterate(tFixes[1], tFixes[2], tFixes[#tFixes])
+                                pos1, pos2 = trilaterate(tFixes[1], tFixes[2], tFixes[3])
                             else
-                                pos1, pos2 = narrow(pos1, pos2, tFixes[#tFixes])
+                                pos1, pos2 = narrow(pos1, pos2, tFixes[3])
                             end
                         end
                     end

projects/core/src/test/resources/test-rom/spec/apis/gps_spec.lua

@@ -16,4 +16,90 @@ describe("The gps library", function()
             expect.error(gps.locate, 1, ""):eq("bad argument #2 (boolean expected, got string)")
         end)
     end)
+
+    describe("on fake computers", function()
+        local fake_computer = require "support.fake_computer"
+
+        local function gps_reciever(x, y, z, fn)
+            local computer = fake_computer.make_computer(1, fn)
+            computer.position = vector.new(x, y, z)
+            fake_computer.add_api(computer, "rom/apis/gps.lua")
+            fake_computer.add_api(computer, "rom/apis/vector.lua")
+
+            local modem = fake_computer.add_modem(computer, "back")
+            return computer, modem
+        end
+
+        local function gps_hosts(computer, modem, positions)
+            local computers = {}
+            for _, position in pairs(positions) do
+                local position = vector.new(position[1], position[2], position[3])
+                local host = fake_computer.make_computer(99, function(env)
+                    env.loadfile("/rom/programs/gps.lua")("host", position.x, position.y, position.z)
+                end)
+                host.position = position
+                fake_computer.add_api(host, "rom/apis/gps.lua")
+                fake_computer.add_api(host, "rom/apis/vector.lua")
+
+                local host_modem = fake_computer.add_modem(host, "back")
+                fake_computer.add_modem_edge(modem, host_modem)
+
+                computers[#computers + 1] = host
+            end
+
+            computers[#computers + 1] = computer -- Run the computer after hosts have started
+            return computers
+        end
+
+        it("locates a computer", function()
+            local computer, modem = gps_reciever(12, 23, 52, function(env)
+                local x, y, z = env.gps.locate()
+                expect({ x, y, z }):same { 12, 23, 52 }
+            end)
+            local computers = gps_hosts(computer, modem, {
+                { 5, 5, 5 },
+                { 10, 5, 5 },
+                { 5, 10, 5 },
+                { 5, 5, 10 },
+            })
+
+            fake_computer.run_all(computers, false)
+            fake_computer.advance_all(computers, 2)
+            fake_computer.run_all(computers, { computer })
+        end)
+
+        it("fails to locate a computer with insufficient hosts", function()
+            local computer, modem = gps_reciever(12, 23, 52, function(env)
+                local x, y, z = env.gps.locate()
+                expect({ x, y, z }):same { nil, nil, nil }
+            end)
+            local computers = gps_hosts(computer, modem, {
+                { 5, 5, 5 },
+                { 10, 5, 5 },
+                { 5, 10, 5 },
+            })
+
+            fake_computer.run_all(computers, false)
+            fake_computer.advance_all(computers, 2)
+            fake_computer.run_all(computers, { computer })
+        end)
+
+        it("doesn't fail on duplicate hosts", function()
+            local computer, modem = gps_reciever(12, 23, 52, function(env)
+                local x, y, z = env.gps.locate()
+                expect({ x, y, z }):same { 12, 23, 52 }
+            end)
+            local computers = gps_hosts(computer, modem, {
+                { 5, 5, 5 },
+                { 5, 5, 5 },
+                { 10, 5, 5 },
+                { 5, 10, 5 },
+                { 5, 5, 10 },
+            })
+
+            fake_computer.run_all(computers, false)
+            fake_computer.advance_all(computers, 2)
+            fake_computer.run_all(computers, { computer })
+        end)
+    end)
 end)

projects/core/src/test/resources/test-rom/spec/support/fake_computer.lua

@@ -56,7 +56,12 @@ local function make_computer(id, fn)
             repeat local _, id = env.os.pullEvent("timer") until id == timer
         end,
     }
+    env.redstone = {
+        getSides = redstone.getSides,
+    }
+    env.rs = env.redstone
     env.sleep = env.os.sleep
+    env.loadfile = function(path, mode, new_env) return loadfile(path, mode, new_env or env) end
     env.dofile = function(path)
         local fn, err = loadfile(path, nil, env)
         if fn then return fn() else error(err, 2) end
@@ -91,7 +96,9 @@ local function make_computer(id, fn)
         end
     end
 
-    return { env = env, peripherals = peripherals, queue_event = queue_event, step = step, co = co, advance = advance }
+    local position = vector.new(0, 0, 0)
+
+    return { env = env, peripherals = peripherals, queue_event = queue_event, step = step, co = co, advance = advance, position = position }
 end
 
 local function parse_channel(c)
@@ -112,10 +119,13 @@ local function add_modem(owner, side)
 
             for _, adjacent in pairs(adjacent) do
                 if adjacent.open[channel] then
-                    adjacent.owner.queue_event("modem_message", adjacent.side, channel, reply_channel, payload, 123)
+                    local distance = (adjacent.owner.position - owner.position):length()
+                    print(("Distance %s .. %s => %d"):format(adjacent.owner.position, owner.position, distance))
+                    adjacent.owner.queue_event("modem_message", adjacent.side, channel, reply_channel, payload, distance)
                 end
             end
         end,
+        isWireless = function() return true end,
     }, { type = "modem" })
     owner.peripherals[side] = peripheral
     return { adjacent = adjacent, side = side, owner = owner, open = open }