1 files changed, 152 insertions, 0 deletions
diff --git a/source/portals.d b/source/portals.d
new file mode 100644
index 0000000..7bb5dc2
--- /dev/null
+++ b/source/portals.d
@@ -0,0 +1,152 @@
+import std.bigint : BigInt;
+import spots : OverlaySource, Spot;
+import std.stdio;
+import std.format;
+
+struct Portal {
+    BigInt y;
+    BigInt x;
+    Portal* pair;
+    this(BigInt y, BigInt x) {
+        this.y = y;
+        this.x = x;
+    }
+
+    void pairWith(ref Portal p) {
+        this.pair = &p;
+        p.pair = &this;
+    }
+
+    void buildMap(ref int[Portal* ] idMap, ref int highId) {
+        idMap[&this] = highId++;
+    }
+
+    string toString(int[Portal* ] idMap)
+    in {
+        assert(pair in idMap);
+    }
+    do {
+        return format!`%s, %s: %d`(y, x, idMap[pair]);
+    }
+
+    void fromString(string s, Portal[int] portalsById) {
+        import std.conv : to;
+        import std.algorithm : until, findSkip;
+        import std.array : array;
+
+        this.y = to!BigInt(s.until(',').array);
+        s.findSkip(", ");
+        this.x = to!BigInt(s.until(':').array);
+        s.findSkip(": ");
+        int id;
+        s.formattedRead!"%d"(id);
+        auto p = id in portalsById;
+        if (p) {
+            p.pairWith(this); // this is a REALLY big bug. Portal() is
+            // being copied by value into the dict,
+            // so it's not using its final ref.
+        }
+
+    }
+}
+
+class Portals {
+    private Portal[int] _portals;
+    private Portal* _lastPortal;
+    private int _nextId;
+    private OverlaySource _overlay;
+
+    this(OverlaySource overlay) {
+        _overlay = overlay;
+    }
+
+    int add(BigInt y, BigInt x) {
+        _portals[_nextId] = Portal(y, x);
+        if (_lastPortal && _lastPortal.pair == null) {
+            _lastPortal.pairWith(_portals[_nextId]);
+        }
+        _lastPortal = &(_portals[_nextId]);
+        _overlay[y, x] = Spot('/', _nextId);
+        return _nextId++;
+    }
+
+    Portal get(int id)
+    in {
+        assert(id in _portals);
+    }
+    do {
+        return _portals[id];
+    }
+
+    void remove(BigInt y, BigInt x) {
+        auto id = _overlay[y, x].id;
+        auto pair = _portals[id].pair;
+        if (pair) {
+            if (_lastPortal.pair == null) {
+                _lastPortal.pairWith(*pair);
+            } else {
+                pair.pair = null;
+            }
+        }
+        _lastPortal = _portals[id].pair;
+        _portals.remove(id);
+        _overlay[y, x] = Spot(' ');
+    }
+
+    immutable string terminator = "END PORTAL DATA\n";
+    void save(File f) {
+        int id = 0;
+        int[Portal* ] idMap;
+        foreach (ref key; _portals.byKey()) {
+            (key in _portals).buildMap(idMap, id);
+        }
+        foreach (ref key; _portals.byKey()) {
+            auto portalRef = key in _portals;
+            f.writefln!`%d @ %s`(idMap[portalRef], portalRef.toString(idMap));
+        }
+
+        f.write(terminator);
+        if (_lastPortal)
+            f.writefln!`%d`(idMap[_lastPortal]);
+    }
+
+    void load(File f) {
+        _nextId = 0;
+        foreach (char[] line; f.lines) {
+            if (line == terminator)
+                break;
+
+            int id;
+            string portalText;
+            line.formattedRead!`%d @ %s`(id, portalText);
+            _portals[id] = Portal();
+            _portals[id].fromString(portalText, _portals);
+            _nextId++;
+        }
+        int id;
+        if (_nextId > 0) {
+            f.readf("%d\n", id);
+            _lastPortal = &(_portals[id]);
+        }
+    }
+
+    unittest {
+        import spots : RandomSource;
+        import std.stdio;
+
+        auto overlay = new OverlaySource(new RandomSource());
+        auto portals = new Portals(overlay);
+
+        portals.add(BigInt(0), BigInt(0));
+        portals.remove(BigInt(0), BigInt(0));
+        int orig = portals.add(BigInt(0), BigInt(0));
+        int sec = portals.add(BigInt(0), BigInt(1));
+        assert(*(portals.get(orig).pair) == portals.get(sec));
+        portals.remove(BigInt(0), BigInt(1));
+        sec = portals.add(BigInt(0), BigInt(2));
+        assert(*(portals.get(orig).pair) == portals.get(sec));
+        orig = portals.add(BigInt(0), BigInt(3));
+        portals.remove(BigInt(0), BigInt(0));
+        assert(*(portals.get(orig).pair) == portals.get(sec));
+    }
+}