#include "pugixml.hpp"
#include <cstddef>
#include <cstring>

// Returns true and increments count if `tag_node`'s first two attributes
// are (value) "highway" then "crossing", matching the original's
// position-based (not name-based) attribute check.
inline bool is_highway_crossing(pugi::xml_node tag_node) {
    pugi::xml_attribute k = tag_node.first_attribute();
    if (!k) return false;

    pugi::xml_attribute v = k.next_attribute();
    if (!v) return false;

    return std::strcmp(k.value(), "highway") == 0 &&
           std::strcmp(v.value(), "crossing") == 0;
}

size_t count_highway_crossings (char* buffer, size_t len) {
    pugi::xml_document doc;
    pugi::xml_parse_result result = doc.load_buffer_inplace(buffer, len, pugi::parse_minimal);
    if (!result) return 0;
    //if (!result) {
    //    fprintf(stderr, "pugixml error: %s at offset %td\n", result.description(), result.offset);
    //}

    size_t count = 0;

    for (pugi::xml_node node : doc.child("osm").children("node")) {
        for (pugi::xml_node tag : node.children("tag")) {
            if (is_highway_crossing(tag)) ++count;
        }
    }

    return count;
}

size_t count_highway_crossings_cheat_and_early_out (char* buffer, size_t len) {
    pugi::xml_document doc;
    pugi::xml_parse_result result = doc.load_buffer_inplace(buffer, len, pugi::parse_minimal);
    if (!result) return 0;

    size_t count = 0;

    for (pugi::xml_node top : doc.child("osm").children()) {
        if (std::strcmp(top.name(), "way") == 0) break;

        for (pugi::xml_node tag : top.children("tag")) {
            if (is_highway_crossing(tag)) ++count;
        }
    }

    return count;
}