import { assetManager, JsonAsset, sys } from 'cc';
import { MiniGamePf } from '../../mx/tools/MiniGameHostInfo';
import { GBundle } from '../game/ConfigRes';

type ChinaProvincePack = {
    /** 坐标放大倍数（lng/lat * s 后为整数） */
    s: number;
    p: Array<{
        n: string;
        /** [minLng, minLat, maxLng, maxLat]，已乘 s */
        b: number[];
        /** 外环，扁平 [lng,lat,lng,lat...]，已乘 s */
        r: number[][];
    }>;
};

type CachePayload = { n: string };

const CACHE_KEY = 'province_locator_v1';
const DATA_PATH = 'config/china_provinces';
const LOCATE_TIMEOUT_MS = 10000;

/**
 * 一次定位 + 本地省界判断。命中后写入本地缓存，之后不再调定位。
 */
export class ProvinceLocator {
    private static _cacheLoaded = false;
    private static _cached: string | null = null;
    private static _inflight: Promise<string> | null = null;
    private static _pack: ChinaProvincePack | null = null;
    /** 空缓存本进程内允许静默重试一次 */
    private static _emptyRetryDone = false;

    /**
     * 返回短省名（广东 / 北京）；未授权、失败或未命中返回空串。
     * @param options.allowEmptyCacheRetry 上次失败空缓存时，本进程内是否允许再定位一次
     * @param options.force 清掉空失败缓存后强制重新定位（授权成功后用）
     */
    static getProvince(options?: { allowEmptyCacheRetry?: boolean; force?: boolean }): Promise<string> {
        this._readCache();
        if (options?.force && this._cached === '') {
            this._cached = null;
            this._emptyRetryDone = false;
        }
        if (this._cached != null && this._cached !== '') return Promise.resolve(this._cached);
        if (this._cached === '') {
            if (!options?.allowEmptyCacheRetry || this._emptyRetryDone) {
                return Promise.resolve('');
            }
            this._emptyRetryDone = true;
        }
        if (this._inflight) return this._inflight;
        this._inflight = this._resolve().finally(() => {
            this._inflight = null;
        });
        return this._inflight;
    }

    private static async _resolve(): Promise<string> {
        const loc = await this._getLatLng();
        if (!loc) return '';
        if ('denied' in loc) {
            this._writeCache('');
            return '';
        }
        const pack = await this._loadPack();
        if (!pack) return '';
        const name = this._hitProvince(loc.lng, loc.lat, pack);
        this._writeCache(name);
        return name;
    }

    private static _readCache(): void {
        if (this._cacheLoaded) return;
        this._cacheLoaded = true;
        try {
            const raw = sys.localStorage.getItem(CACHE_KEY);
            if (!raw) return;
            const o = JSON.parse(raw) as CachePayload;
            if (typeof o?.n === 'string') this._cached = o.n;
        } catch {
            /* ignore */
        }
    }

    private static _writeCache(name: string): void {
        this._cached = name;
        try {
            const payload: CachePayload = { n: name };
            sys.localStorage.setItem(CACHE_KEY, JSON.stringify(payload));
        } catch {
            /* ignore */
        }
    }

    private static _loadPack(): Promise<ChinaProvincePack | null> {
        if (this._pack) return Promise.resolve(this._pack);
        return new Promise((resolve) => {
            const take = (bundle: ReturnType<typeof assetManager.getBundle>) => {
                if (!bundle) {
                    resolve(null);
                    return;
                }
                const cached = bundle.get(DATA_PATH, JsonAsset);
                if (cached?.json) {
                    this._pack = cached.json as ChinaProvincePack;
                    resolve(this._pack);
                    return;
                }
                bundle.load(DATA_PATH, JsonAsset, (err, asset) => {
                    if (err || !asset?.json) {
                        resolve(null);
                        return;
                    }
                    this._pack = asset.json as ChinaProvincePack;
                    resolve(this._pack);
                });
            };
            const existed = assetManager.getBundle(GBundle.First);
            if (existed) {
                take(existed);
                return;
            }
            assetManager.loadBundle(GBundle.First, (err, bundle) => take(err ? null : bundle));
        });
    }

    private static _getLatLng(): Promise<{ lat: number; lng: number } | { denied: true } | null> {
        const host = MiniGamePf.api();
        const wx = (window as Record<string, unknown>)['wx'] as MiniLocationApi | undefined;
        const api = (host?.getLocation ? host : wx) as MiniLocationApi | undefined;
        if (!api?.getLocation) return Promise.resolve(null);
        return new Promise((resolve) => {
            let done = false;
            const finish = (v: { lat: number; lng: number } | { denied: true } | null) => {
                if (done) return;
                done = true;
                resolve(v);
            };
            const timer = setTimeout(() => finish(null), LOCATE_TIMEOUT_MS);
            const opts: Parameters<MiniLocationApi['getLocation']>[0] = {
                success: (res) => {
                    clearTimeout(timer);
                    const lat = Number(res?.latitude);
                    const lng = Number(res?.longitude);
                    if (!Number.isFinite(lat) || !Number.isFinite(lng)) finish(null);
                    else finish({ lat, lng });
                },
                fail: (res) => {
                    clearTimeout(timer);
                    const msg = String(res?.errMsg ?? '');
                    if (/auth deny|authorize|permission|privacy/i.test(msg)) finish({ denied: true });
                    else finish(null);
                },
            };
            // B 站无 type；抖音/微信传 gcj02 对齐国内省界
            if (!MiniGamePf.isBl()) opts.type = 'gcj02';
            api.getLocation(opts);
        });
    }

    private static _hitProvince(lng: number, lat: number, pack: ChinaProvincePack): string {
        const s = pack.s || 10000;
        const x = lng * s;
        const y = lat * s;
        const list = pack.p;
        for (let i = 0; i < list.length; i++) {
            const item = list[i];
            const b = item.b;
            if (x < b[0] || y < b[1] || x > b[2] || y > b[3]) continue;
            const rings = item.r;
            for (let k = 0; k < rings.length; k++) {
                if (this._pointInRing(x, y, rings[k])) return item.n;
            }
        }
        return '';
    }

    /** 射线法：点是否在多边形内（ring 为已乘 s 的扁平坐标） */
    private static _pointInRing(x: number, y: number, ring: number[]): boolean {
        const n = (ring.length / 2) | 0;
        let inside = false;
        let j = n - 1;
        for (let i = 0; i < n; i++) {
            const xi = ring[i * 2];
            const yi = ring[i * 2 + 1];
            const xj = ring[j * 2];
            const yj = ring[j * 2 + 1];
            const dy = yj - yi;
            if (dy !== 0 && (yi > y) !== (yj > y) && x < ((xj - xi) * (y - yi)) / dy + xi) {
                inside = !inside;
            }
            j = i;
        }
        return inside;
    }
}

type MiniLocationApi = {
    getLocation: (opts: {
        type?: string;
        success?: (res: { latitude?: number; longitude?: number }) => void;
        fail?: (res: { errMsg?: string }) => void;
    }) => void;
};