#include <esp_wifi_types.h>
#include <esp_wifi.h>
#include <esp_log.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <sys/param.h>

#include "httpd_utils/captive.h"
#include "httpd_utils/fd_to_ipv4.h"
#include "httpd_utils/redirect.h"
#include <common_utils/utils.h>

static const char *TAG="captive";

const char * __attribute__((weak))
httpd_captive_redirect_get_domain(void)
{
    return "fb_node.captive";
}

esp_err_t __attribute__((weak))
httpd_captive_redirect_get_url(httpd_req_t *r, char *buf, size_t maxlen)
{
    buf = append(buf, "http://", &maxlen);
    buf = append(buf, httpd_captive_redirect_get_domain(), &maxlen);
    append(buf, "/", &maxlen);

    return ESP_OK;
}

esp_err_t httpd_captive_redirect(httpd_req_t *r)
{
    // must be static to survive being used in the redirect header
    static char s_buf[64];

    wifi_mode_t mode = 0;
    esp_wifi_get_mode(&mode);

    // Check if we have an softap interface. No point checking IPs and hostnames if the client can't be on AP.
    if (mode == WIFI_MODE_STA || mode == WIFI_MODE_NULL) {
        goto no_redirect;
    }

    int fd = httpd_req_to_sockfd(r);

    tcpip_adapter_ip_info_t apip;
    tcpip_adapter_get_ip_info(TCPIP_ADAPTER_IF_AP, &apip);

    u32_t client_addr;
    if(ESP_OK != fd_to_ipv4(fd, &client_addr)) {
        return ESP_FAIL;
    }

    ESP_LOGD(TAG, "[captive] Client addr = 0x%08x, ap addr 0x%08x, ap nmask 0x%08x",
             client_addr,
             apip.ip.addr,
             apip.netmask.addr
    );

    // Check if client IP looks like from our AP dhcps
    if ((client_addr & apip.netmask.addr) != (apip.ip.addr & apip.netmask.addr)) {
        ESP_LOGD(TAG, "[captive] Client not in AP IP range");
        goto no_redirect;
    }

    // Get requested hostname from the header
    esp_err_t rv = httpd_req_get_hdr_value_str(r, "Host", s_buf, 64);
    if (rv != ESP_OK) {
        ESP_LOGW(TAG, "[captive] No host in request?");
        goto no_redirect;
    }

    ESP_LOGD(TAG, "[captive] Candidate for redirect: %s%s", s_buf, r->uri);

    // Never redirect if host is an IP
    if (strlen(s_buf)>7) {
        bool isIP = 1;
        for (int x = 0; x < strlen(s_buf); x++) {
            if (s_buf[x] != '.' && (s_buf[x] < '0' || s_buf[x] > '9')) {
                isIP = 0;
                break;
            }
        }

        if (isIP) {
            ESP_LOGD(TAG, "[captive] Access via IP, no redirect needed");
            goto no_redirect;
        }
    }

    // Redirect if host differs
    // - this can be e.g. connectivitycheck.gstatic.com or the equivalent for ios

    if (0 != strcmp(s_buf, httpd_captive_redirect_get_domain())) {
        ESP_LOGD(TAG, "[captive] Host differs, redirecting...");

        httpd_captive_redirect_get_url(r, s_buf, 64);
        return httpd_redirect_to(r, s_buf);
    } else {
        ESP_LOGD(TAG, "[captive] Host is OK");
        goto no_redirect;
    }

    no_redirect:
    return ESP_ERR_NOT_FOUND;
}