#include <time.h>
#include <stdio.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pthread.h>
#include <arpa/inet.h>
#include <sys/socket.h>

#include "sockio.h"

const uint16_t SERVER_PORT = 1092;
const uint16_t MAX_CLIENT_NUM = 20;

const char WWW_PATH[] = "../www";

const char USERNAME[] = "3190101092";
const char PASSWORD[] = "1092";

int serv_sock;                                 // server socket
int clnt_socks[MAX_CLIENT_NUM];                // client sockets
struct sockaddr_in clnt_addrs[MAX_CLIENT_NUM]; // client addresses

// test string prefix
int strprefix(const char *s, const char *prefix)
{
    for (; *s && *prefix; s++, prefix++)
    {
        if (*s != *prefix)
        {
            return 0;
        }
    }

    if (*prefix)
    {
        return 0;
    }

    return 1;
}

// test string suffix
int strsuffix(const char *s, const char *suffix)
{
    int s_len = strlen(s), suffix_len = strlen(suffix);
    if (s_len < suffix_len)
    {
        return 0;
    }

    for (s += s_len - suffix_len; *suffix; s++, suffix++)
    {
        if (*s != *suffix)
        {
            return 0;
        }
    }

    return 1;
}

// test object key-value pair
int strmatch(const char *s, const char *key, const char *value)
{
    int key_len = strlen(key);

    const char *p = strstr(s, key);
    if (p == NULL || p[key_len] != '=')
    {
        return 0;
    }

    for (p += key_len + 1; *p && *p != '&' && *value; p++, value++)
    {
        if (*p != *value)
        {
            return 0;
        }
    }

    if (*p && *p != '&' || *value)
    {
        return 0;
    }

    return 1;
}

// get content type from filename
const char *getcontenttype(const char *s)
{
    if (strsuffix(s, ".html"))
    {
        return "text/html";
    }
    else if (strsuffix(s, ".jpg"))
    {
        return "image/jpeg";
    }

    return "text/plain";
}

// send http header
void send_header(int clnt_sock, struct buffer *send_buf, struct buffer *line_buf,
                 const char *protocol, const char *status, const char *content_type, size_t content_length)
{
    line_buf->len = sprintf(line_buf->buf, "%s %s\r\n"
                                           "Content-Type: %s; charset=utf-8\r\n"
                                           "Content-Length: %lu\r\n"
                                           "\r\n",
                            protocol, status, content_type, content_length);
    sputline(clnt_sock, send_buf, line_buf);

    printf("\tresponse: protocol = %s, status = %s, content type = %s, content length = %lu.\n", protocol, status, content_type, content_length);
}

// handle connection
void *conn(void *id)
{
    uint16_t clnt_id = *(uint16_t *)id;
    int clnt_sock = clnt_socks[clnt_id];

    struct buffer recv_buf, send_buf, line_buf, body_buf;
    memset(&recv_buf, 0, sizeof(recv_buf));
    memset(&send_buf, 0, sizeof(send_buf));
    memset(&line_buf, 0, sizeof(line_buf));
    memset(&body_buf, 0, sizeof(body_buf));

    char method[32], url[1024], protocol[32];

    for (;;)
    {
        // request line
        int n = sgetline(clnt_sock, &recv_buf, &line_buf);
        if (n < 0)
        {
            break;
        }

        {
            char *s = line_buf.buf, *p = method;
            for (; *s != ' '; s++, p++)
            {
                *p = *s;
            }
            *p = '\0';

            s++, p = url;
            for (; *s != ' '; s++, p++)
            {
                *p = *s;
            }
            *p = '\0';

            s++, p = protocol;
            for (; *s != '\r'; s++, p++)
            {
                *p = *s;
            }
            *p = '\0';
        }

        // request headers
        size_t content_length = 0;

        for (;;)
        {
            n = sgetline(clnt_sock, &recv_buf, &line_buf);
            if (n <= 2)
            {
                break;
            }

            if (strprefix(line_buf.buf, "Content-Length: "))
            {
                for (char *s = line_buf.buf + strlen("Content-Length: "); *s != '\r'; s++)
                {
                    content_length = content_length * 10 + *s - '0';
                }
            }
        }
        if (n < 0)
        {
            break;
        }

        printf("Client %hu request: method = %s, url = %s, protocol = %s, content length = %lu.\n", clnt_id, method, url, protocol, content_length);

        // request body
        char *request_body = (char *)malloc(content_length + 1);
        for (char *s = request_body; s < request_body + content_length; s++)
        {
            *s = sgetc(clnt_sock, &recv_buf);
        }
        request_body[content_length] = '\0';

        if (strcmp(method, "GET") == 0)
        {
            FILE *fp = fopen(url + 1, "rb");
            if (fp == NULL)
            {
                body_buf.len = sprintf(body_buf.buf, "The requested file %s was not found on this server", url);
                send_header(clnt_sock, &send_buf, &line_buf, protocol, "404 Not Found", "text/plain", body_buf.len);
                sputline(clnt_sock, &send_buf, &body_buf);
            }
            else
            {
                fseek(fp, 0, SEEK_END);
                send_header(clnt_sock, &send_buf, &line_buf, protocol, "200 OK", getcontenttype(url), ftell(fp));
                fseek(fp, 0, SEEK_SET);

                for (;;)
                {
                    body_buf.len = fread(body_buf.buf, 1, BUF_SIZE, fp);
                    if (body_buf.len == 0)
                    {
                        break;
                    }

                    sputline(clnt_sock, &send_buf, &body_buf);
                }
            }
        }
        else if (strcmp(method, "POST") == 0)
        {
            if (strcmp(url, "/dopost") == 0)
            {
                int login = strmatch(request_body, "login", USERNAME) && strmatch(request_body, "pass", PASSWORD);
                body_buf.len = sprintf(body_buf.buf, "<html><body>%s</body></html>", login ? "登录成功" : "登录失败");
                send_header(clnt_sock, &send_buf, &line_buf, protocol, "200 OK", "text/html", body_buf.len);
                sputline(clnt_sock, &send_buf, &body_buf);
            }
            else
            {
                body_buf.len = sprintf(body_buf.buf, "The requested URL %s was not found on this server", url);
                send_header(clnt_sock, &send_buf, &line_buf, protocol, "404 Not Found", "text/plain", body_buf.len);
                sputline(clnt_sock, &send_buf, &body_buf);
            }
        }

        free(request_body);

        sflush(clnt_sock, &send_buf);

        if (strcmp(method, "POST") == 0)
        {
            break;
        }
    }

    close(clnt_sock);
    printf("Client %hu disconnected.\n", clnt_id);
    clnt_socks[clnt_id] = -1;

    return NULL;
}

// close sockets before exit
void stop_server(int sig)
{
    for (uint16_t i = 0; i < MAX_CLIENT_NUM; i++)
    {
        if (clnt_socks[i] != -1)
        {
            close(clnt_socks[i]);
            printf("Client %hu disconnected.\n", i);
            clnt_socks[i] = -1;
        }
    }

    close(serv_sock);
    puts("Stop listening.");

    exit(0);
}

int main()
{
    chdir(WWW_PATH);

    memset(clnt_socks, -1, sizeof(clnt_socks));

    // create server socket
    serv_sock = socket(AF_INET, SOCK_STREAM, IPPROTO_TCP);
    if (serv_sock == -1)
    {
        puts("Create socket failed.");
        exit(1);
    }

    // bind address to server socket
    struct sockaddr_in serv_addr;
    memset(&serv_addr, 0, sizeof(serv_addr));
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_addr.s_addr = htonl(INADDR_ANY);
    serv_addr.sin_port = htons(SERVER_PORT);
    if (bind(serv_sock, (const struct sockaddr *)&serv_addr, sizeof(serv_addr)) == -1)
    {
        puts("Bind socket failed.");
        exit(1);
    }

    // listen on server socket
    if (listen(serv_sock, MAX_CLIENT_NUM) == -1)
    {
        puts("Listen socket failed.");
        exit(1);
    }

    puts("Start listening on port 1092...");

    signal(SIGINT, stop_server);

    for (;;)
    {
        // accept connection
        struct sockaddr_in clnt_addr;
        socklen_t clnt_addr_size = sizeof(clnt_addr);
        int clnt_sock = accept(serv_sock, (struct sockaddr *)&clnt_addr, &clnt_addr_size);
        if (clnt_sock == -1)
        {
            puts("Create socket failed.");
            continue;
        }

        // allocate client id
        for (uint16_t i = 0; i < MAX_CLIENT_NUM; i++)
        {
            if (clnt_socks[i] == -1)
            {
                clnt_socks[i] = clnt_sock;
                clnt_addrs[i] = clnt_addr;

                // create thread
                pthread_t pid;
                if (pthread_create(&pid, NULL, conn, &i) != 0)
                {
                    puts("Create thread failed.");
                    clnt_socks[i] = -1;
                    break;
                }

                printf("Client %hu (%s:%hu) connected. pid = %lu.\n", i, inet_ntoa(clnt_addr.sin_addr), ntohs(clnt_addr.sin_port), pid);

                break;
            }
        }
    }

    return 0;
}