/**
 * @file wget.c
 * @brief Simple HTTP client for ClaudeOS.
 *
 * Downloads a resource from an HTTP server using a TCP connection.
 * Only supports HTTP/1.0 GET with IP addresses (no DNS).
 *
 * Usage:
 *   wget <ip>[:<port>]/<path>
 *   wget <ip>                    - fetches /
 *
 * Examples:
 *   wget 10.0.2.2/index.html
 *   wget 10.0.2.2:8080/api/data
 *   wget 192.168.1.1
 */

#include "syscalls.h"

typedef unsigned char uint8_t;

/**
 * Parse a decimal number from a string.
 * Advances *s past the digits.
 */
static uint32_t parse_uint(const char **s) {
    uint32_t val = 0;
    while (**s >= '0' && **s <= '9') {
        val = val * 10 + (uint32_t)(**s - '0');
        (*s)++;
    }
    return val;
}

/**
 * Parse an IPv4 dotted-decimal address into a 32-bit host-order integer.
 * Returns 0 on failure.
 */
static uint32_t parse_ip(const char **s) {
    uint32_t ip = 0;
    for (int i = 0; i < 4; i++) {
        uint32_t octet = parse_uint(s);
        if (octet > 255) return 0;
        ip = (ip << 8) | octet;
        if (i < 3) {
            if (**s != '.') return 0;
            (*s)++;
        }
    }
    return ip;
}

/**
 * Print a decimal number.
 */
static void print_dec(uint32_t val) {
    char buf[12];
    int i = 0;
    if (val == 0) { putchar('0'); return; }
    while (val > 0) {
        buf[i++] = '0' + (char)(val % 10);
        val /= 10;
    }
    while (i > 0) putchar(buf[--i]);
}

/**
 * Build the HTTP GET request.
 * Returns length of the request string.
 */
static uint32_t build_request(char *buf, uint32_t bufsize,
                              const char *host, const char *path) {
    uint32_t pos = 0;

    /* "GET <path> HTTP/1.0\r\nHost: <host>\r\nConnection: close\r\n\r\n" */
    const char *parts[] = {
        "GET ", path, " HTTP/1.0\r\nHost: ", host,
        "\r\nConnection: close\r\n\r\n", (const char *)0
    };

    for (int i = 0; parts[i]; i++) {
        const char *s = parts[i];
        while (*s && pos < bufsize - 1) {
            buf[pos++] = *s++;
        }
    }
    buf[pos] = '\0';
    return pos;
}

/**
 * Format an IP address as a dotted-decimal string.
 */
static void ip_to_str(uint32_t ip, char *buf) {
    int pos = 0;
    for (int i = 3; i >= 0; i--) {
        uint32_t octet = (ip >> (i * 8)) & 0xFF;
        char tmp[4];
        int ti = 0;
        if (octet == 0) { tmp[ti++] = '0'; }
        else {
            while (octet > 0) { tmp[ti++] = '0' + (char)(octet % 10); octet /= 10; }
        }
        while (ti > 0) buf[pos++] = tmp[--ti];
        if (i > 0) buf[pos++] = '.';
    }
    buf[pos] = '\0';
}

int main(void) {
    char url[256];

    /* Get URL from ARG1 */
    if (getenv("ARG1", url, sizeof(url)) < 0 || url[0] == '\0') {
        puts("Usage: wget <ip>[:<port>]/<path>\n");
        puts("  e.g. wget 10.0.2.2/index.html\n");
        return 1;
    }

    /* Parse: skip optional "http://" prefix */
    const char *p = url;
    if (strncmp(p, "http://", 7) == 0) {
        p += 7;
    }

    /* Parse IP address */
    uint32_t ip = parse_ip(&p);
    if (ip == 0) {
        puts("wget: invalid IP address\n");
        return 1;
    }

    /* Parse optional port */
    uint32_t port = 80;
    if (*p == ':') {
        p++;
        port = parse_uint(&p);
        if (port == 0 || port > 65535) {
            puts("wget: invalid port\n");
            return 1;
        }
    }

    /* Parse path (default to /) */
    const char *path = "/";
    if (*p == '/') {
        path = p;
    } else if (*p != '\0') {
        puts("wget: invalid URL format\n");
        return 1;
    }

    /* Build host string for Host header */
    char host_str[64];
    ip_to_str(ip, host_str);

    /* Print what we're doing */
    puts("Connecting to ");
    puts(host_str);
    putchar(':');
    print_dec(port);
    puts(path);
    puts("...\n");

    /* Create TCP socket */
    int32_t sockfd = socket(SOCK_TCP);
    if (sockfd < 0) {
        puts("wget: failed to create socket\n");
        return 1;
    }

    /* Connect */
    if (connect(sockfd, ip, port) < 0) {
        puts("wget: connect failed\n");
        return 1;
    }

    /* Wait for connection to establish (poll with yield) */
    int timeout = 500; /* ~5 seconds at ~100 yields/sec */
    while (timeout > 0) {
        int32_t state = sockstate(sockfd);
        if (state == TCP_STATE_ESTABLISHED) break;
        if (state == TCP_STATE_CLOSED) {
            puts("wget: connection refused\n");
            return 1;
        }
        yield();
        timeout--;
    }
    if (timeout <= 0) {
        puts("wget: connection timed out\n");
        return 1;
    }

    puts("Connected.\n");

    /* Build and send HTTP request */
    char req[512];
    uint32_t req_len = build_request(req, sizeof(req), host_str, path);

    int32_t sent = net_send(sockfd, req, req_len);
    if (sent < 0) {
        puts("wget: send failed\n");
        return 1;
    }

    /* Receive response */
    puts("--- Response ---\n");
    char buf[512];
    int done = 0;
    int recv_timeout = 1000;

    while (!done && recv_timeout > 0) {
        int32_t n = net_recv(sockfd, buf, sizeof(buf) - 1);
        if (n > 0) {
            buf[n] = '\0';
            write(1, buf, (uint32_t)n);
            recv_timeout = 200; /* Reset timeout on data */
        } else if (n < 0) {
            /* Connection closed or error */
            done = 1;
        } else {
            /* No data yet */
            yield();
            recv_timeout--;
        }
    }

    puts("\n--- End ---\n");

    /* Close socket - we use close() which goes through SYS_CLOSE.
     * For sockets, we should ideally have a socket-specific close,
     * but for simplicity, the socket will be cleaned up on process exit. */

    return 0;
}