import { mapSchema } from "@nengine/core-schema";
import { UNWALKABLE_TILES } from "@nengine/core-systems";
import type { MapDef } from "@nengine/core";

/** Editor canvas tile size in pixels (matches the game viewport's 32px tiles). */
export const TILE_SIZE = 32;

/** Tile id `erase` writes when the map uses it (the engine's neutral terrain). */
export const DEFAULT_ERASE_TILE = "grass";

/**
 * Strict-typed editor model over a MapDef. The model owns a deep-cloned
 * working copy of the def; grid operations never mutate the def passed to
 * `createMapModel`. Pure logic — node-testable, no DOM.
 */
export interface MapModel {
  /** Working copy of the map definition (paint/erase/spawn/walkable edits live here). */
  def: MapDef;
  /** Index of the terrain layer: the layer named "ground", else the first layer. */
  groundIndex: number;
  /** Palette tile ids: ids present on the map plus ids added via `addTileId`
   * (never includes the empty string). */
  palette: string[];
  /** True when any serializable edit (paint/erase/spawn/walkable) is unsaved. */
  dirty: boolean;
}

export function createMapModel(def: unknown): MapModel | null {
  const result = mapSchema.safeParse(def);
  if (!result.success) return null;
  const model = cloneDef(result.data);
  const groundIndex = Math.max(0, model.layers.findIndex((layer) => layer.name === "ground"));
  return { def: model, groundIndex, palette: collectIds(model), dirty: false };
}

/** Unique tile ids currently on the map (all layers, row-major first-seen order). */
export function collectTileIds(model: MapModel): string[] {
  return collectIds(model.def);
}

/** Paint `tileId` onto the ground layer at (x, y). Out-of-bounds is a no-op. */
export function paint(model: MapModel, x: number, y: number, tileId: string): void {
  if (x < 0 || y < 0) return;
  const row = model.def.layers[model.groundIndex]?.data[y];
  if (row === undefined || x >= row.length) return;
  if (row[x] === tileId) return;
  row[x] = tileId;
  model.dirty = true;
  if (tileId !== "" && !model.palette.includes(tileId)) model.palette.push(tileId);
}

/** Erase the ground cell at (x, y): write `DEFAULT_ERASE_TILE` when the map
 * uses it, else the first palette tile id, else "" (void). */
export function erase(model: MapModel, x: number, y: number): void {
  paint(model, x, y, eraseTileId(model));
}

/** Move the spawn point. Out-of-range coordinates are clamped into the map;
 * non-integer coordinates are rejected (no-op). */
export function setSpawn(model: MapModel, x: number, y: number): void {
  if (!Number.isInteger(x) || !Number.isInteger(y)) return;
  model.def.spawn.x = clampInt(x, 0, model.def.width - 1);
  model.def.spawn.y = clampInt(y, 0, model.def.height - 1);
  model.dirty = true;
}

/**
 * Toggle a tile id's walkable record entry. When the id is currently `false`
 * the key is deleted (restoring the engine's fallback semantics, D33); when it
 * is `true` or absent it is set to `false`. The record only ever carries
 * `false` entries — a fallback-blocked id (e.g. water) toggled off the record
 * still stays non-walkable at runtime; making such an id walkable needs
 * `walkable: { <id>: true }` in YAML (editor v1, documented).
 */
export function toggleWalkable(model: MapModel, tileId: string): void {
  if (tileId === "") return;
  if (model.def.walkable?.[tileId] === false) {
    const walkable = { ...(model.def.walkable ?? {}) };
    delete walkable[tileId];
    if (Object.keys(walkable).length === 0) {
      delete model.def.walkable;
    } else {
      model.def.walkable = walkable;
    }
  } else {
    model.def.walkable = { ...(model.def.walkable ?? {}), [tileId]: false };
  }
  model.dirty = true;
}

/** Register a palette tile id that may not be on the map yet. No def change. */
export function addTileId(model: MapModel, tileId: string): void {
  if (tileId === "") return;
  if (!model.palette.includes(tileId)) model.palette.push(tileId);
}

/** Walkability of a tile id, mirroring the engine's resolution (D33): the
 * declared `walkable` value wins; undeclared ids fall back to the engine's
 * UNWALKABLE_TILES constant (default `{"water"}`). */
export function isWalkableTile(model: MapModel, tileId: string): boolean {
  const declared = model.def.walkable?.[tileId];
  if (typeof declared === "boolean") return declared;
  return !UNWALKABLE_TILES.has(tileId);
}

/** Serialize the working copy as a fresh plain MapDef, validated by
 * `mapSchema.safeParse`. Returns null when the working copy is invalid —
 * invalid edits must not serialize. */
export function serialize(model: MapModel): MapDef | null {
  const result = mapSchema.safeParse(model.def);
  if (!result.success) return null;
  return cloneDef(result.data);
}

/** Clear the unsaved-changes flag (call after a successful save). */
export function markSaved(model: MapModel): void {
  model.dirty = false;
}

/**
 * Editor canvas tile color. grass/tilled/water keep the render package's
 * TILE_COLORS values for visual continuity; every other tile id gets a stable
 * hash-derived hue (same id → same color). This is a palette approximation —
 * asset-accurate rendering is playtest territory.
 */
const TILE_PALETTE: Record<string, string> = {
  grass: "#7cb342",
  tilled: "#8d6e63",
  water: "#4fc3f7",
};

export const UNKNOWN_TILE_COLOR = "#5b6470";

export function tileColor(tileId: string): string {
  const known = TILE_PALETTE[tileId];
  if (known !== undefined) return known;
  if (tileId === "") return UNKNOWN_TILE_COLOR;
  return `hsl(${stableHue(tileId)} 55% 55%)`;
}

/** Canvas pixel offset → grid tile (pure geometry; negative offsets give
 * negative tiles, which edit ops reject/clamp). */
export function pointToTile(offsetX: number, offsetY: number, tileSize: number = TILE_SIZE): { x: number; y: number } {
  return { x: Math.floor(offsetX / tileSize), y: Math.floor(offsetY / tileSize) };
}

function eraseTileId(model: MapModel): string {
  if (model.palette.includes(DEFAULT_ERASE_TILE)) return DEFAULT_ERASE_TILE;
  return model.palette[0] ?? "";
}

function collectIds(def: MapDef): string[] {
  const ids: string[] = [];
  for (const layer of def.layers) {
    for (const row of layer.data) {
      for (const tile of row) {
        if (tile !== "" && !ids.includes(tile)) ids.push(tile);
      }
    }
  }
  return ids;
}

function cloneDef(def: MapDef): MapDef {
  const clone: MapDef = {
    id: def.id,
    width: def.width,
    height: def.height,
    tilesetRef: def.tilesetRef,
    spawn: { x: def.spawn.x, y: def.spawn.y },
    layers: def.layers.map((layer) => ({
      name: layer.name,
      data: layer.data.map((row) => [...row]),
    })),
  };
  if (def.walkable !== undefined) clone.walkable = { ...def.walkable };
  if (def.tiles !== undefined) clone.tiles = { ...def.tiles };
  return clone;
}

function clampInt(value: number, min: number, max: number): number {
  return Math.min(Math.max(value, min), max);
}

function stableHue(id: string): number {
  let hash = 0;
  for (let i = 0; i < id.length; i++) {
    hash = (hash * 31 + id.charCodeAt(i)) >>> 0;
  }
  return hash % 360;
}