import { Vec3 } from 'cc';
import { CELL_PIXEL } from './GridConstants';

/**
 * 与 Unity Grid 一致：CellLayout Isometric Z-as-Y，CellSize (1, 0.5, 1)。
 * 缩放后 halfW=CELL/2, halfH=CELL/4。
 */
const HALF_W = CELL_PIXEL * 0.5;
const HALF_H = CELL_PIXEL * 0.25;

if (!Number.isFinite(HALF_W) || HALF_W <= 0) {
    console.error('[GridCoords] CELL_PIXEL 无效，请检查 GridConstants 模块加载');
}

export function cellToWorld(cell: Vec3): Vec3 {
    const x = cell.x;
    const y = cell.y;
    return new Vec3((x - y) * HALF_W, (x + y) * HALF_H, 0);
}

/** Unity Tilemap tileAnchor (0.5,0.5)：精灵 pivot 对齐格子中心 */
export function cellToWorldCenter(cell: Vec3): Vec3 {
    const w = cellToWorld(cell);
    return new Vec3(w.x, w.y + HALF_H, 0);
}

export function worldToCell(world: Vec3): Vec3 {
    const cx = (world.y / HALF_H + world.x / HALF_W) * 0.5;
    const cy = (world.y / HALF_H - world.x / HALF_W) * 0.5;
    return new Vec3(Math.round(cx), Math.round(cy), 0);
}

/** 输入为世界坐标下的格子中心（与 Tilemap tileAnchor 一致） */
export function worldCenterToCell(world: Vec3): Vec3 {
    return worldToCell(new Vec3(world.x, world.y - HALF_H, world.z));
}

/** 世界坐标吸附到最近格子中心 */
export function snapWorldToCellCenter(world: Vec3, out?: Vec3): Vec3 {
    const cell = worldToCell(world);
    const snapped = cellToWorld(cell);
    if (out) {
        out.set(snapped);
        return out;
    }
    return snapped;
}

export function formatCellKey(x: number, y: number): string {
    return `${x},${y}`;
}

export function parseCellKey(key: string): { x: number; y: number } | null {
    const parts = key.split(',');
    if (parts.length !== 2) return null;
    const x = parseInt(parts[0], 10);
    const y = parseInt(parts[1], 10);
    if (Number.isNaN(x) || Number.isNaN(y)) return null;
    return { x, y };
}

/** 烘焙瓦片节点名 g_1_0 / b_-2_1 → 格子坐标 */
export function parseTileNodeName(name: string | undefined | null): { layer: 'ground' | 'border'; x: number; y: number } | null {
    if (!name) return null;
    const m = name.match(/^([gb])_(-?\d+)_(-?\d+)$/);
    if (!m) return null;
    return {
        layer: m[1] === 'g' ? 'ground' : 'border',
        x: parseInt(m[2], 10),
        y: parseInt(m[3], 10),
    };
}

export function tileNodeName(layer: 'ground' | 'border', x: number, y: number): string {
    const p = layer === 'ground' ? 'g' : 'b';
    return `${p}_${x}_${y}`;
}

export function getHalfCellSize(): { halfW: number; halfH: number } {
    return { halfW: HALF_W, halfH: HALF_H };
}

/** 等距绘制深度（连续值，移动插值用；与 compareIsoDrawOrder 配套） */
export function isoDrawDepthFromWorld(world: Vec3): { x: number; y: number } {
    const cx = (world.y / HALF_H + world.x / HALF_W) * 0.5;
    const cy = (world.y / HALF_H - world.x / HALF_W) * 0.5;
    return { x: cx, y: cy };
}