#include <stdio.h>
#include <stdlib.h>

#include "lua.h"
#include "lauxlib.h"
#include "geohash.h"

// 算法 来源 https://github.com/yinqiwen/geohash-int

static int _geohash_encode(lua_State *L)
{
    double lat = (double)luaL_checknumber(L, 1);
    double lon = (double)luaL_checknumber(L, 2);
    uint8_t step = (uint8_t)luaL_checknumber(L, 3);

    // 纬度
    double lat_min = (double)luaL_checknumber(L, 4);
    double lat_max = (double)luaL_checknumber(L, 5);

    // 经度
    double lon_min = (double)luaL_checknumber(L, 6);
    double lon_max = (double)luaL_checknumber(L, 7);

    // printf("==== _geohash_encode latL:%lf lon:%lf step:%d ===== \n", lat, lon, step);
    // printf(" ^^^^^^ _geohash_encode lat_max:%lf lat_min:%lf lon_max:%lf lon_min:%lf ^^^^ \n", lat_max, lat_min, lon_max, lon_min);

    GeoHashRange lat_range, lon_range;
    lat_range.max = lat_max;
    lat_range.min = lat_min;
    lon_range.max = lon_max;
    lon_range.min = lon_min;

    GeoHashBits fast_hash;
    geohash_fast_encode(lat_range, lon_range, lat, lon, step, &fast_hash);
    lua_pushnumber(L, fast_hash.bits);
    return 1;
}

static int _geohash_neighbors(lua_State *L)
{
    double bits = (double)luaL_checknumber(L, 1);
    uint8_t step = (uint8_t)luaL_checknumber(L, 2);

    GeoHashBits fast_hash;
    fast_hash.bits = bits;
    fast_hash.step = step;

    GeoHashNeighbors neighbors;
    geohash_get_neighbors(fast_hash, &neighbors);

    lua_pushnumber(L, neighbors.north.bits);
    lua_pushnumber(L, neighbors.north_east.bits);
    lua_pushnumber(L, neighbors.north_west.bits);
    lua_pushnumber(L, neighbors.south.bits);
    lua_pushnumber(L, neighbors.south_east.bits);
    lua_pushnumber(L, neighbors.south_west.bits);
    lua_pushnumber(L, neighbors.east.bits);
    lua_pushnumber(L, neighbors.west.bits);

    return 8;
}

LUALIB_API int luaopen_geohash(lua_State *L)
{
    luaL_checkversion(L);

    luaL_Reg l[] = {
        {"hashfastencode", _geohash_encode},
        {"hashgetneighbors", _geohash_neighbors},
        {NULL, NULL}};

    luaL_newlib(L, l);
    return 1;
}