// httpd.cpp - Lightweight HTTP Server for AGI Frontend (C++)
#include <iostream>
#include <string>
#include <cstring>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <fcntl.h>
#include <sys/stat.h>

constexpr int PORT = 8080;
constexpr int BUFFER_SIZE = 4096;

const char *HTTP_200 = "HTTP/1.1 200 OK\r\n";
const char *HTTP_404 = "HTTP/1.1 404 Not Found\r\nContent-Length: 9\r\n\r\nNot Found";
const char *CONTENT_HTML = "Content-Type: text/html\r\n";

void send_file(int client_fd, const char *filepath) {
    int fd = open(filepath, O_RDONLY);
    if (fd < 0) {
        write(client_fd, HTTP_404, strlen(HTTP_404));
        return;
    }

    struct stat st;
    fstat(fd, &st);

    char header[512];
    snprintf(header, sizeof(header),
             "%s%sContent-Length: %ld\r\n\r\n",
             HTTP_200, CONTENT_HTML, st.st_size);

    write(client_fd, header, strlen(header));

    char buf[BUFFER_SIZE];
    ssize_t n;
    while ((n = read(fd, buf, sizeof(buf))) > 0) {
        write(client_fd, buf, n);
    }

    close(fd);
}

void handle_request(int client_fd) {
    char buffer[BUFFER_SIZE];
    ssize_t bytes_read = read(client_fd, buffer, sizeof(buffer) - 1);

    if (bytes_read <= 0) {
        close(client_fd);
        return;
    }

    buffer[bytes_read] = '\0';

    /* Parse request line */
    char method[16], path[256];
    sscanf(buffer, "%s %s", method, path);

    std::cout << "[" << method << "] " << path << std::endl;

    /* Route requests */
    if (strcmp(path, "/") == 0 || strcmp(path, "/index.html") == 0) {
        send_file(client_fd, "frontend/index.html");
    } else {
        write(client_fd, HTTP_404, strlen(HTTP_404));
    }

    close(client_fd);
}

int main() {
    int server_fd, client_fd;
    struct sockaddr_in addr;

    server_fd = socket(AF_INET, SOCK_STREAM, 0);
    if (server_fd < 0) {
        perror("socket");
        return 1;
    }

    int opt = 1;
    setsockopt(server_fd, SOL_SOCKET, SO_REUSEADDR, &opt, sizeof(opt));

    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = INADDR_ANY;
    addr.sin_port = htons(PORT);

    if (bind(server_fd, (struct sockaddr*)&addr, sizeof(addr)) < 0) {
        perror("bind");
        close(server_fd);
        return 1;
    }

    if (listen(server_fd, 10) < 0) {
        perror("listen");
        close(server_fd);
        return 1;
    }

    std::cout << "🧠 AGI Frontend Server running on http://localhost:" << PORT << std::endl;
    std::cout << "   Serving: frontend/index.html\n" << std::endl;

    while (1) {
        client_fd = accept(server_fd, NULL, NULL);
        if (client_fd < 0) {
            perror("accept");
            continue;
        }

        handle_request(client_fd);
    }

    close(server_fd);
    return 0;
}