#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <curl/curl.h>
#include "ipcheck.h"
#include "log.h"

static const char *SERVICES[] = {
    "https://ipv4.icanhazip.com",
    "https://api4.ipify.org",
    "https://ipv4.wtfismyip.com/text",
    "https://v4.ident.me",
    "https://ipv4.am.i.mullvad.net/ip",
    "https://4.ident.me",
    "https://4.tnedi.me",
};

#define SERVICE_COUNT (int)(sizeof(SERVICES) / sizeof(SERVICES[0]))

typedef struct {
    char buf[IPCHECK_MAX_IP_LEN];
    size_t len;
} IPBuf;

static size_t write_cb(void *data, size_t size, size_t nmemb, void *userp) {
    IPBuf *out = (IPBuf *)userp;
    size_t total = size * nmemb;
    if (out->len + total >= IPCHECK_MAX_IP_LEN) return 0;
    memcpy(out->buf + out->len, data, total);
    out->len += total;
    return total;
}

int ipcheck_get_public_ip(char *out_ip) {
    char results[SERVICE_COUNT][IPCHECK_MAX_IP_LEN];
    int valid = 0;

    CURL *curl = curl_easy_init();
    if (!curl) return -1;

    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_cb);
    curl_easy_setopt(curl, CURLOPT_TIMEOUT, IPCHECK_TIMEOUT_SECS);
    curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);

    for (int i = 0; i < SERVICE_COUNT; i++) {
        IPBuf buf = { .buf = {0}, .len = 0 };

        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &buf);
        curl_easy_setopt(curl, CURLOPT_URL, SERVICES[i]);

        CURLcode res = curl_easy_perform(curl);

        if (res != CURLE_OK) continue;

        long http_code = 0;
        curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &http_code);
        if (http_code != 200) continue;

        buf.buf[buf.len] = '\0';
        if (sscanf(buf.buf, IPCHECK_IP_SCAN_FMT, results[valid]) != 1) continue;
        valid++;
    }

    curl_easy_cleanup(curl);

    if (valid < IPCHECK_MIN_RESPONDERS) {
        log_warn("ipcheck: only %d/%d services responded, need at least %d",
                valid, SERVICE_COUNT, IPCHECK_MIN_RESPONDERS);
        return -1;
    }

    for (int i = 0; i < valid; i++) {
        int count = 0;
        for (int j = 0; j < valid; j++) {
            if (strcmp(results[i], results[j]) == 0) count++;
        }
        if (count * 2 > valid) {
            strncpy(out_ip, results[i], IPCHECK_MAX_IP_LEN - 1);
            out_ip[IPCHECK_MAX_IP_LEN - 1] = '\0';
            return 0;
        }
    }

    log_warn("ipcheck: no strict majority among %d/%d responders",
            valid, SERVICE_COUNT);
    return -2;
}