import { MAP_H, MAP_W, SIZE } from "./mapUtils.js";

export const DEFAULT_WORLD_PADDING_X = MAP_W;
export const DEFAULT_WORLD_PADDING_Y = MAP_H;

const NEGATIVE_ONE_FIELDS = new Set([
  "adminId",
  "prefectureRegionId",
  "regionId",
  "municipalityId",
  "naturalCompartmentId",
  "watershedId",
]);

function isCellField(value) {
  return ArrayBuffer.isView(value) && typeof value.length === "number" && value.length === SIZE;
}

function defaultForField(name, Constructor) {
  if (name === "sea") return 1;
  if (name === "elevation") return 0.08;
  if (name === "seaLevel") return undefined;
  if (NEGATIVE_ONE_FIELDS.has(name)) return -1;
  if (Constructor === Float32Array || Constructor === Float64Array) return 0;
  return 0;
}

function makeWorldField(name, source, worldWidth, worldHeight, originX, originY) {
  const Constructor = NEGATIVE_ONE_FIELDS.has(name) ? Int32Array : source.constructor;
  const out = new Constructor(worldWidth * worldHeight);
  const fallback = defaultForField(name, Constructor);
  if (fallback !== 0) out.fill(fallback);

  for (let y = 0; y < MAP_H; y++) {
    const srcRow = y * MAP_W;
    const dstRow = (originY + y) * worldWidth + originX;
    for (let x = 0; x < MAP_W; x++) out[dstRow + x] = source[srcRow + x];
  }
  return out;
}


function sanitizeInitialWorldFields(fields, width, height) {
  const sea = fields.sea;
  if (!sea) return;
  const adminFields = ["adminId", "municipalityId", "prefectureRegionId"];
  for (let i = 0; i < width * height; i++) {
    const isSea = Boolean(sea[i]);
    if (fields.landMask) fields.landMask[i] = isSea ? 0 : (fields.prefectureMask?.[i] ? 1 : fields.landMask[i]);
    if (fields.humanRegionMask && isSea) fields.humanRegionMask[i] = 0;
    if (isSea) {
      for (const key of adminFields) if (fields[key]) fields[key][i] = -1;
      if (fields.landuse) fields.landuse[i] = 0;
    } else {
      if (fields.municipalityId && fields.adminId && fields.municipalityId[i] < 0 && fields.adminId[i] >= 0) fields.municipalityId[i] = fields.adminId[i];
    }
  }
}

export function createWorldMap(initialMap, options = {}) {
  const paddingX = Number.isFinite(options.paddingX) ? Math.max(0, Math.floor(options.paddingX)) : DEFAULT_WORLD_PADDING_X;
  const paddingY = Number.isFinite(options.paddingY) ? Math.max(0, Math.floor(options.paddingY)) : DEFAULT_WORLD_PADDING_Y;
  const worldWidth = MAP_W + paddingX * 2;
  const worldHeight = MAP_H + paddingY * 2;
  const originX = paddingX;
  const originY = paddingY;
  const fields = {};

  for (const [name, value] of Object.entries(initialMap || {})) {
    if (isCellField(value)) fields[name] = makeWorldField(name, value, worldWidth, worldHeight, originX, originY);
  }

  if (!fields.sea) {
    fields.sea = new Uint8Array(worldWidth * worldHeight);
    fields.sea.fill(1);
  }
  if (!fields.elevation) {
    fields.elevation = new Float32Array(worldWidth * worldHeight);
    fields.elevation.fill(0.08);
  }
  sanitizeInitialWorldFields(fields, worldWidth, worldHeight);

  return {
    seed: initialMap?.seed ?? 0,
    width: worldWidth,
    height: worldHeight,
    originX,
    originY,
    sourceWidth: initialMap?.width || MAP_W,
    sourceHeight: initialMap?.height || MAP_H,
    sourceMap: initialMap,
    fields,
    invalidatedRects: [],
    humanPatchHistory: [],
    generatedRects: [{
      x0: originX,
      y0: originY,
      x1: originX + MAP_W,
      y1: originY + MAP_H,
      terrainType: initialMap?.terrainTemplate?.terrainType || initialMap?.terrainDebug?.terrainType || "auto",
      label: initialMap?.terrainTemplate?.terrainTypeLabel || initialMap?.terrainDebug?.terrainTypeLabel || "Initial generation",
    }],
  };
}

export function createInitialCamera(world) {
  return {
    x: world?.originX || 0,
    y: world?.originY || 0,
  };
}

export function clampCameraToWorld(camera, world, viewWidth = MAP_W, viewHeight = MAP_H) {
  if (!camera || !world) return { x: 0, y: 0 };
  const maxX = Math.max(0, world.width - viewWidth);
  const maxY = Math.max(0, world.height - viewHeight);
  return {
    x: Math.min(Math.max(Math.round(camera.x || 0), 0), maxX),
    y: Math.min(Math.max(Math.round(camera.y || 0), 0), maxY),
  };
}

function expandRectByOffset(rect, dx, dy) {
  if (!rect) return rect;
  return { ...rect, x0: rect.x0 + dx, y0: rect.y0 + dy, x1: rect.x1 + dx, y1: rect.y1 + dy };
}

function shiftSelectionShape(shape, dx, dy) {
  if (!shape?.polygon) return shape;
  return {
    ...shape,
    x0: Number.isFinite(shape.x0) ? shape.x0 + dx : shape.x0,
    y0: Number.isFinite(shape.y0) ? shape.y0 + dy : shape.y0,
    x1: Number.isFinite(shape.x1) ? shape.x1 + dx : shape.x1,
    y1: Number.isFinite(shape.y1) ? shape.y1 + dy : shape.y1,
    polygon: shape.polygon.map((p) => ({ ...p, x: p.x + dx, y: p.y + dy })),
  };
}

function shiftPatchMetadata(item, dx, dy) {
  const out = expandRectByOffset(item, dx, dy);
  for (const sub of ["coreRect", "writeRect", "repairRect", "contextRect", "blendRect", "transportReachRect"]) {
    if (out?.[sub]) out[sub] = expandRectByOffset(out[sub], dx, dy);
  }
  if (out?.selectionShape) out.selectionShape = shiftSelectionShape(out.selectionShape, dx, dy);
  return out;
}

function shiftRectCollections(world, dx, dy) {
  if (!dx && !dy) return;
  for (const key of ["generatedRects", "invalidatedRects", "humanPatchHistory"]) {
    if (!Array.isArray(world[key])) continue;
    world[key] = world[key].map((item) => shiftPatchMetadata(item, dx, dy));
  }
  if (world.lastPatchResult) world.lastPatchResult = shiftPatchMetadata(world.lastPatchResult, dx, dy);
}

export function expandWorldMap(world, margins = {}) {
  if (!world) return { world, dx: 0, dy: 0, expanded: false };
  const left = Math.max(0, Math.floor(margins.left || 0));
  const right = Math.max(0, Math.floor(margins.right || 0));
  const top = Math.max(0, Math.floor(margins.top || 0));
  const bottom = Math.max(0, Math.floor(margins.bottom || 0));
  if (!left && !right && !top && !bottom) return { world, dx: 0, dy: 0, expanded: false };
  const oldWidth = world.width;
  const oldHeight = world.height;
  const newWidth = oldWidth + left + right;
  const newHeight = oldHeight + top + bottom;
  const newFields = {};
  for (const [name, field] of Object.entries(world.fields || {})) {
    if (!ArrayBuffer.isView(field)) continue;
    const Constructor = NEGATIVE_ONE_FIELDS.has(name) ? Int32Array : field.constructor;
    const out = new Constructor(newWidth * newHeight);
    const fallback = defaultForField(name, Constructor);
    if (fallback !== 0) out.fill(fallback);
    for (let y = 0; y < oldHeight; y++) {
      const srcRow = y * oldWidth;
      const dstRow = (y + top) * newWidth + left;
      for (let x = 0; x < oldWidth; x++) out[dstRow + x] = field[srcRow + x];
    }
    newFields[name] = out;
  }
  world.width = newWidth;
  world.height = newHeight;
  world.originX += left;
  world.originY += top;
  world.fields = newFields;
  shiftRectCollections(world, left, top);
  return { world, dx: left, dy: top, expanded: true };
}

export function ensureWorldPaddingForCamera(world, camera, viewWidth = MAP_W, viewHeight = MAP_H, padding = Math.floor(Math.min(MAP_W, MAP_H) * 0.45)) {
  if (!world || !camera) return { dx: 0, dy: 0, expanded: false };
  const grow = Math.max(64, Math.floor(padding));
  const margins = { left: 0, right: 0, top: 0, bottom: 0 };
  if (camera.x < grow) margins.left = grow;
  if (camera.y < grow) margins.top = grow;
  if (camera.x + viewWidth > world.width - grow) margins.right = grow;
  if (camera.y + viewHeight > world.height - grow) margins.bottom = grow;
  return expandWorldMap(world, margins);
}