#include <stdio.h>
#include <string.h>

#include "pico/stdlib.h"
#include "pico/cyw43_arch.h"

#include "lwip/pbuf.h"
#include "lwip/tcp.h"

#define SERVER_IP   "192.168.161.25"
#define SERVER_PORT 8080

typedef struct {
    struct tcp_pcb *pcb;
    ip_addr_t       remote;
    volatile bool   done;
} client_t;

static void finish(client_t *c) {
    if (c->pcb) {
        tcp_arg(c->pcb, NULL);
        tcp_recv(c->pcb, NULL);
        tcp_err(c->pcb, NULL);
        tcp_close(c->pcb);
        c->pcb = NULL;
    }
    c->done = true;
}

static void send_line(struct tcp_pcb *pcb, const char *msg) {
    err_t err = tcp_write(pcb, msg, strlen(msg), TCP_WRITE_FLAG_COPY);
    if (err == ERR_OK) {
        tcp_output(pcb);
    } else {
        printf("tcp_write err=%d\n", err);
    }
}

static err_t on_recv(void *arg, struct tcp_pcb *pcb, struct pbuf *p, err_t err) {
    client_t *c = (client_t *)arg;
    if (!p) {
        printf("Server hat Verbindung geschlossen\n");
        finish(c);
        return ERR_OK;
    }

    char buf[64];
    uint16_t n = pbuf_copy_partial(p, buf, sizeof(buf) - 1, 0);
    buf[n] = '\0';

    printf("<< %s", buf);

    if (strstr(buf, "ping")) {
        printf(">> pong\n");
        send_line(pcb, "pong\n");
    }

    tcp_recved(pcb, p->tot_len);
    pbuf_free(p);
    return ERR_OK;
}

static void on_err(void *arg, err_t err) {
    client_t *c = (client_t *)arg;
    printf("TCP-Fehler: %d\n", err);
    // lwIP hat das pcb in diesem Callback bereits freigegeben.
    c->pcb = NULL;
    c->done = true;
}

static err_t on_connected(void *arg, struct tcp_pcb *pcb, err_t err) {
    client_t *c = (client_t *)arg;
    if (err != ERR_OK) {
        printf("connect-Callback err=%d\n", err);
        finish(c);
        return err;
    }
    printf("Verbunden — sende Hallo\n");
    const char *msg = "Hallo vom Pico 2W\n";
    err = tcp_write(pcb, msg, strlen(msg), TCP_WRITE_FLAG_COPY);
    if (err == ERR_OK) {
        tcp_output(pcb);
    } else {
        printf("tcp_write err=%d\n", err);
    }
    return err;
}

int main(void) {
    stdio_init_all();
    sleep_ms(2000); // Zeit, das USB-Serial-Terminal zu oeffnen

    if (cyw43_arch_init()) {
        printf("cyw43_arch_init fehlgeschlagen\n");
        return 1;
    }
    cyw43_arch_enable_sta_mode();

    printf("Verbinde mit WLAN \"%s\"...\n", WIFI_SSID);
    if (cyw43_arch_wifi_connect_timeout_ms(WIFI_SSID, WIFI_PASSWORD,
                                           CYW43_AUTH_WPA2_AES_PSK, 30000)) {
        printf("WLAN-Verbindung fehlgeschlagen\n");
        return 1;
    }
    printf("WLAN OK\n");

    client_t client = {0};
    if (!ip4addr_aton(SERVER_IP, &client.remote)) {
        printf("Ungueltige Server-IP\n");
        return 1;
    }

    client.pcb = tcp_new_ip_type(IP_GET_TYPE(&client.remote));
    if (!client.pcb) {
        printf("tcp_new fehlgeschlagen\n");
        return 1;
    }
    tcp_arg(client.pcb, &client);
    tcp_recv(client.pcb, on_recv);
    tcp_err(client.pcb, on_err);

    printf("Verbinde TCP %s:%d\n", SERVER_IP, SERVER_PORT);
    cyw43_arch_lwip_begin();
    err_t err = tcp_connect(client.pcb, &client.remote, SERVER_PORT, on_connected);
    cyw43_arch_lwip_end();
    if (err != ERR_OK) {
        printf("tcp_connect err=%d\n", err);
        return 1;
    }

    while (!client.done) {
        sleep_ms(100);
    }

    cyw43_arch_deinit();
    return 0;
}