#pragma once
#include "stdint.h"
#include "stddef.h"

#ifdef __cplusplus
extern "C" {
#endif

#define ETHERTYPE_IPv4 0x0800
#define ETHERTYPE_ARP  0x0806

#define IP_PROTO_ICMP  1
#define IP_PROTO_TCP   6
#define IP_PROTO_UDP   17

#define ICMP_ECHO_REPLY   0
#define ICMP_ECHO_REQUEST 8

#pragma pack(push, 1)

typedef struct {
    uint8_t  dest_mac[6];
    uint8_t  src_mac[6];
    uint16_t ethertype;
} eth_hdr_t;

typedef struct {
    uint16_t hw_type;
    uint16_t proto_type;
    uint8_t  hw_len;
    uint8_t  proto_len;
    uint16_t opcode;
    uint8_t  sender_mac[6];
    uint32_t sender_ip;
    uint8_t  target_mac[6];
    uint32_t target_ip;
} arp_hdr_t;

typedef struct {
    uint8_t  version_ihl;
    uint8_t  tos;
    uint16_t total_length;
    uint16_t id;
    uint16_t flags_fragment;
    uint8_t  ttl;
    uint8_t  protocol;
    uint16_t checksum;
    uint32_t src_ip;
    uint32_t dst_ip;
} ipv4_hdr_t;

typedef struct {
    uint8_t  type;
    uint8_t  code;
    uint16_t checksum;
    uint16_t id;
    uint16_t sequence;
} icmp_hdr_t;

typedef struct {
    uint16_t src_port;
    uint16_t dst_port;
    uint32_t seq_num;
    uint32_t ack_num;
    uint8_t  data_offset_reserved;
    uint8_t  flags;
    uint16_t window_size;
    uint16_t checksum;
    uint16_t urgent_ptr;
} tcp_hdr_t;

typedef struct {
    uint16_t src_port;
    uint16_t dst_port;
    uint16_t length;
    uint16_t checksum;
} udp_hdr_t;

typedef struct {
    uint16_t id;
    uint16_t flags;
    uint16_t qdcount;
    uint16_t ancount;
    uint16_t nscount;
    uint16_t arcount;
} dns_hdr_t;

#define TCP_FLAG_FIN 0x01
#define TCP_FLAG_SYN 0x02
#define TCP_FLAG_RST 0x04
#define TCP_FLAG_PSH 0x08
#define TCP_FLAG_ACK 0x10
#define TCP_FLAG_URG 0x20

#pragma pack(pop)

typedef struct {
    uint32_t ip;
    uint32_t netmask;
    uint32_t gateway;
    uint32_t dns_server;
    uint8_t  mac[6];
} net_config_t;

extern net_config_t g_net_cfg;

// Net API
void net_init(void);
uint16_t net_checksum(const void *buf, size_t len);
uint16_t net_tcp_checksum(uint32_t src_ip, uint32_t dst_ip, const tcp_hdr_t *tcp, size_t tcp_len);
int net_send_arp_request(uint32_t target_ip);
int net_send_icmp_ping(uint32_t target_ip, uint16_t seq);
int net_poll_icmp_reply(uint32_t *from_ip, uint16_t *seq);
int net_dns_resolve(const char *domain, uint32_t *out_ip);
int net_dhcp_discover(void);
int net_http_get(uint32_t target_ip, uint16_t port, const char *path, const char *host_header, char *out_body, size_t max_body_len);
int net_http_get_url(const char *url, char *out_body, size_t max_body_len);
uint32_t parse_ip(const char *str);
void format_ip(uint32_t ip, char *buf);

#ifdef __cplusplus
}
#endif