feat: add gift zone city team and mashup mode

js/gameplay/difficulty/generate-board.js

@@ -105,6 +105,38 @@ function placePieces(piecePool, levelPreset, rng) {
   return placedPieces
 }
 
+export function generateBoardFromDefinition({
+  boardId,
+  cityId,
+  levelId,
+  seed,
+  elements,
+  levelPreset,
+  extraState = {},
+}) {
+  const effectiveSeed = seed ?? levelPreset.seedBase
+  const rng = createRng(effectiveSeed)
+  const selectedElements = [...elements]
+  const counts = normalizePiecesPerElement(levelPreset.piecesPerElement, levelPreset.elementCount)
+  const piecePool = createPiecePool(selectedElements, counts)
+  const pieces = placePieces(shuffleWithRng(piecePool, rng), levelPreset, rng)
+  const overlapGraph = buildOverlapGraph(pieces)
+  const boardState = {
+    boardId: boardId ?? `${cityId}-${levelId}-${effectiveSeed}`,
+    cityId,
+    levelId,
+    seed: effectiveSeed,
+    pieces,
+    overlapGraph,
+    metrics: {},
+    ...extraState,
+  }
+
+  boardState.metrics = evaluateBoard(boardState, levelPreset)
+
+  return boardState
+}
+
 export function generateBoard({ cityId, levelId, seed, contentSystem }) {
   const city = contentSystem.getCity(cityId)
   const levelPreset = contentSystem.getLevelPreset(cityId, levelId)
@@ -116,23 +148,14 @@ export function generateBoard({ cityId, levelId, seed, contentSystem }) {
   const effectiveSeed = seed ?? levelPreset.seedBase
   const rng = createRng(effectiveSeed)
   const selectedElements = pickElements(city, levelPreset, rng)
-  const counts = normalizePiecesPerElement(levelPreset.piecesPerElement, levelPreset.elementCount)
-  const piecePool = createPiecePool(selectedElements, counts)
-  const pieces = placePieces(shuffleWithRng(piecePool, rng), levelPreset, rng)
-  const overlapGraph = buildOverlapGraph(pieces)
-  const boardState = {
-    boardId: `${cityId}-${levelId}-${effectiveSeed}`,
+
+  return generateBoardFromDefinition({
     cityId,
     levelId,
     seed: effectiveSeed,
-    pieces,
-    overlapGraph,
-    metrics: {},
-  }
-
-  boardState.metrics = evaluateBoard(boardState, levelPreset)
-
-  return boardState
+    elements: selectedElements,
+    levelPreset,
+  })
 }
 
 export default generateBoard

js/gameplay/difficulty/generate-mashup-board.js

@@ -0,0 +1,99 @@
+import { generateBoardFromDefinition } from './generate-board.js'
+import { createRng, shuffleWithRng } from './random.js'
+
+function createMashupLevelPreset(elementCount) {
+  return {
+    id: 1,
+    seedBase: 31001,
+    elementCount,
+    piecesPerElement: Array.from({ length: elementCount }, () => 3),
+    layers: 4,
+    density: 'medium_high',
+  }
+}
+
+function getSourceCities(cityIds, contentSystem) {
+  return cityIds
+    .map((cityId) => contentSystem.getCity(cityId))
+    .filter(Boolean)
+}
+
+function createCityElementPools(cities, rng) {
+  return cities.map((city) => ({
+    cityId: city.id,
+    cursor: 0,
+    elements: shuffleWithRng(
+      city.elements.map((element) => ({
+        ...element,
+        sourceCityId: city.id,
+        sourceCityName: city.display.name,
+      })),
+      rng,
+    ),
+  }))
+}
+
+function pickMashupElements(cities, targetCount, rng) {
+  const pools = createCityElementPools(cities, rng)
+  const selected = []
+
+  while (selected.length < targetCount) {
+    let didAdd = false
+
+    for (const pool of pools) {
+      const element = pool.elements[pool.cursor]
+      if (!element) {
+        continue
+      }
+
+      selected.push(element)
+      pool.cursor += 1
+      didAdd = true
+
+      if (selected.length === targetCount) {
+        break
+      }
+    }
+
+    if (!didAdd) {
+      break
+    }
+  }
+
+  return selected
+}
+
+export function generateMashupBoard({ cityIds, seed, contentSystem }) {
+  const cities = getSourceCities(cityIds, contentSystem)
+
+  if (cities.length === 0) {
+    throw new Error('Mashup mode requires at least one source city')
+  }
+
+  const effectiveSeed = seed ?? 31001
+  const rng = createRng(effectiveSeed)
+  const maxElementCount = cities.reduce((sum, city) => sum + city.elements.length, 0)
+  const elementCount = Math.min(8, maxElementCount)
+  const levelPreset = createMashupLevelPreset(elementCount)
+  const selectedElements = pickMashupElements(cities, elementCount, rng)
+
+  return generateBoardFromDefinition({
+    boardId: `mashup-${effectiveSeed}`,
+    cityId: 'mashup',
+    levelId: 1,
+    seed: effectiveSeed,
+    elements: selectedElements,
+    levelPreset,
+    extraState: {
+      sourceCityIds: cities.map((city) => city.id),
+      elementDefinitions: selectedElements.map((element) => ({
+        elementId: element.id,
+        name: element.name,
+        sourceCityId: element.sourceCityId,
+        sourceCityName: element.sourceCityName,
+      })),
+    },
+  })
+}
+
+export default generateMashupBoard

js/gameplay/difficulty/index.js

@@ -1,6 +1,7 @@
 export { classifyDeadlock } from './classify-deadlock.js'
 export { evaluateBoard } from './evaluate-board.js'
 export { generateBoard } from './generate-board.js'
+export { generateMashupBoard } from './generate-mashup-board.js'
 export {
   buildOverlapGraph,
   getClickablePieces,