Add multi-cell reach triggers

tools/validate_data.ps1

@@ -239,6 +239,50 @@ if (Has-Prop $campaign "chapters") {
     }
 }
 
+function Check-Unit-Reaches-Cells($Source, [string]$Context, [int]$Width, [int]$Height, $Rows) {
+    $hasPos = Has-Prop $Source "pos"
+    $hasCells = Has-Prop $Source "cells"
+    if ($hasPos -and $hasCells) {
+        Fail "$Context must use either pos or cells, not both."
+    }
+    if (-not $hasPos -and -not $hasCells) {
+        Fail "$Context is missing pos or cells."
+    }
+
+    $cellEntries = @()
+    if ($hasPos) {
+        $cellEntries += ,$Source.pos
+    } else {
+        if (-not ($Source.cells -is [System.Array])) {
+            Fail "$Context cells must be an array."
+        }
+        $cellEntries = @($Source.cells)
+        if ($cellEntries.Count -le 0) {
+            Fail "$Context cells must not be empty."
+        }
+    }
+
+    $seenCells = New-Object System.Collections.Generic.HashSet[string]
+    foreach ($entry in $cellEntries) {
+        $cell = Resolve-Cell $entry $Context
+        $x = [int]$cell.X
+        $y = [int]$cell.Y
+        if ($Width -ge 0 -and $Height -ge 0 -and ($x -lt 0 -or $y -lt 0 -or $x -ge $Width -or $y -ge $Height)) {
+            Fail "$Context is outside map at [$x,$y]."
+        }
+        if ($null -ne $Rows) {
+            $terrainKey = Terrain-At $Rows $x $y
+            if ([int]$terrain.$terrainKey.move_cost.foot -ge 99 -and [int]$terrain.$terrainKey.move_cost.mounted -ge 99 -and [int]$terrain.$terrainKey.move_cost.archer -ge 99) {
+                Fail "$Context targets impassable terrain at [$x,$y]."
+            }
+        }
+        $key = "$x,$y"
+        if (-not $seenCells.Add($key)) {
+            Fail "$Context has duplicate cell [$x,$y]."
+        }
+    }
+}
+
 function Check-Condition($Condition, [string]$ScenarioId, $EventIds, [int]$Width = -1, [int]$Height = -1, $Rows = $null, $KnownUnitIds = $null) {
     if ($Condition -is [System.Array]) {
         foreach ($entry in $Condition) {
@@ -279,21 +323,7 @@ function Check-Condition($Condition, [string]$ScenarioId, $EventIds, [int]$Width
         }
     }
     if ($type -eq "unit_reaches_tile") {
-        if (-not (Has-Prop $Condition "pos")) {
-            Fail "Scenario $ScenarioId unit_reaches_tile condition is missing pos."
-        }
-        $cell = Resolve-Cell $Condition.pos "Scenario $ScenarioId unit_reaches_tile condition"
-        $x = [int]$cell.X
-        $y = [int]$cell.Y
-        if ($Width -ge 0 -and $Height -ge 0 -and ($x -lt 0 -or $y -lt 0 -or $x -ge $Width -or $y -ge $Height)) {
-            Fail "Scenario $ScenarioId unit_reaches_tile condition is outside map at [$x,$y]."
-        }
-        if ($null -ne $Rows) {
-            $terrainKey = Terrain-At $Rows $x $y
-            if ([int]$terrain.$terrainKey.move_cost.foot -ge 99 -and [int]$terrain.$terrainKey.move_cost.mounted -ge 99 -and [int]$terrain.$terrainKey.move_cost.archer -ge 99) {
-                Fail "Scenario $ScenarioId unit_reaches_tile condition targets impassable terrain at [$x,$y]."
-            }
-        }
+        Check-Unit-Reaches-Cells $Condition "Scenario $ScenarioId unit_reaches_tile condition" $Width $Height $Rows
         $unitIdsValue = $null
         if (Has-Prop $Condition "unit_ids") {
             $unitIdsValue = $Condition.unit_ids
@@ -336,19 +366,7 @@ function Check-Condition($Condition, [string]$ScenarioId, $EventIds, [int]$Width
 }
 
 function Check-Unit-Reaches-Event-When($When, [string]$ScenarioId, [int]$Width, [int]$Height, $Rows, $KnownUnitIds) {
-    if (-not (Has-Prop $When "pos")) {
-        Fail "Scenario $ScenarioId unit_reaches_tile event is missing pos."
-    }
-    $cell = Resolve-Cell $When.pos "Scenario $ScenarioId unit_reaches_tile event"
-    $x = [int]$cell.X
-    $y = [int]$cell.Y
-    if ($x -lt 0 -or $y -lt 0 -or $x -ge $Width -or $y -ge $Height) {
-        Fail "Scenario $ScenarioId unit_reaches_tile event is outside map at [$x,$y]."
-    }
-    $terrainKey = Terrain-At $Rows $x $y
-    if ([int]$terrain.$terrainKey.move_cost.foot -ge 99 -and [int]$terrain.$terrainKey.move_cost.mounted -ge 99 -and [int]$terrain.$terrainKey.move_cost.archer -ge 99) {
-        Fail "Scenario $ScenarioId unit_reaches_tile event targets impassable terrain at [$x,$y]."
-    }
+    Check-Unit-Reaches-Cells $When "Scenario $ScenarioId unit_reaches_tile event" $Width $Height $Rows
 
     $unitIdsValue = $null
     if (Has-Prop $When "unit_ids") {