#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_string.h>
#include <ngx_file.h>
#include <ngx_hunk.h>
#include <ngx_event_write.h>
#include <ngx_http.h>
#include <ngx_http_output_filter.h>
#include <ngx_http_event_proxy_handler.h>

ngx_http_module_t  ngx_http_proxy_module_ctx;


static ngx_chain_t *ngx_http_proxy_create_request(ngx_http_request_t *r);
static int ngx_http_proxy_connect(ngx_http_request_t *r,
                                  struct sockaddr_in *addr,
                                  char *addr_text);
static int ngx_http_proxy_send_request(ngx_event_t *ev);

static int ngx_http_proxy_read_response_header(ngx_event_t *ev);
static int ngx_http_proxy_process_status_line(ngx_http_request_t *r,
                                               ngx_http_proxy_ctx_t *p);

static int ngx_http_proxy_read_response_body(ngx_event_t *ev);
static int ngx_http_proxy_write_to_client(ngx_event_t *ev);

static int ngx_read_http_proxy_status_line(ngx_http_proxy_ctx_t *ctx);


static char conn_close[] = "Connection: close" CRLF;


/* AF_INET only */


int ngx_http_proxy_handler(ngx_http_request_t *r)
{
    struct sockaddr_in     addr;
    ngx_chain_t           *chain;
    ngx_http_proxy_ctx_t  *p;

    p = (ngx_http_proxy_ctx_t *)
                         ngx_http_get_module_ctx(r, ngx_http_proxy_module_ctx);

    if (p == NULL) {
        ngx_http_create_ctx(r, p, ngx_http_proxy_module_ctx,
                            sizeof(ngx_http_proxy_ctx_t));
    }

    chain = ngx_http_proxy_create_request(r);
    if (chain == NULL) {
        return NGX_ERROR;
    }

    p->out = chain;

    ngx_memzero(&addr, sizeof(struct sockaddr_in));
    addr.sin_family = AF_INET;
    addr.sin_addr.s_addr = inet_addr("127.0.0.1");
    addr.sin_port = htons(9000);

    return ngx_http_proxy_connect(r, &addr, "connecting to 127.0.0.1:9000");
}


static ngx_chain_t *ngx_http_proxy_create_request(ngx_http_request_t *r)
{
    int     i;
    size_t  len;
    ngx_hunk_t       *hunk;
    ngx_chain_t      *chain;
    ngx_table_elt_t  *header;

    /* 2 is for "\r\n" after request line
       and 2 is for "\r\n" at the header end */
    len = r->request_line.len + 2 + 2;

    /* "Connection: close\r\n" */
    len += sizeof(conn_close) - 1;

    header = (ngx_table_elt_t *) r->headers_in.headers->elts;
    for (i = 0; i < r->headers_in.headers->nelts; i++) {
        if (&header[i] == r->headers_in.host) {
            continue;
        }

        if (&header[i] == r->headers_in.connection) {
            continue;
        }

        /* 2 is for ": " and 2 is for "\r\n" */
        len += header[i].key.len + 2 + header[i].value.len + 2;
    }

    /* STUB */ len++;

    ngx_test_null(hunk, ngx_create_temp_hunk(r->pool, len, 0, 0), NULL);
    ngx_add_hunk_to_chain(chain, hunk, r->pool, NULL);

    ngx_memcpy(hunk->last.mem, r->request_line.data, r->request_line.len);
    hunk->last.mem += r->request_line.len;
    *(hunk->last.mem++) = CR; *(hunk->last.mem++) = LF;

    ngx_memcpy(hunk->last.mem, conn_close, sizeof(conn_close) - 1);
    hunk->last.mem += sizeof(conn_close) - 1;

    for (i = 0; i < r->headers_in.headers->nelts; i++) {
        if (&header[i] == r->headers_in.host) {
            continue;
        }

        if (&header[i] == r->headers_in.connection) {
            continue;
        }

        ngx_memcpy(hunk->last.mem, header[i].key.data, header[i].key.len);
        hunk->last.mem += header[i].key.len;

        *(hunk->last.mem++) = ':'; *(hunk->last.mem++) = ' ';

        ngx_memcpy(hunk->last.mem, header[i].value.data, header[i].value.len);
        hunk->last.mem += header[i].value.len;

        *(hunk->last.mem++) = CR; *(hunk->last.mem++) = LF;

        ngx_log_debug(r->connection->log, "proxy: '%s: %s'" _
                      header[i].key.data _ header[i].value.data);
    }

    /* add "\r\n" at the header end */
    *(hunk->last.mem++) = CR; *(hunk->last.mem++) = LF;

    /* STUB */ *(hunk->last.mem++) = '\0';
    ngx_log_debug(r->connection->log, "PROXY:\n'%s'" _ hunk->pos.mem);

    return chain;
}


static int ngx_http_proxy_connect(ngx_http_request_t *r,
                                  struct sockaddr_in *addr,
                                  char *addr_text)
{
    int                  rc;
    ngx_err_t            err;
    ngx_socket_t         s;
    ngx_event_t         *rev, *wev;
    ngx_connection_t    *c, *pc;
    ngx_http_log_ctx_t  *ctx;

    c = r->connection;
    ctx = c->log->data;
    ctx->action = addr_text;

    s = ngx_socket(AF_INET, SOCK_STREAM, IPPROTO_IP, 0);
    if (s == -1) {
        ngx_log_error(NGX_LOG_ALERT, c->log, ngx_socket_errno,
                      ngx_socket_n " failed");
        return NGX_ERROR;
    }

#if 0
    if (rcvbuf) {
        if (setsockopt(sock, SOL_SOCKET, SO_RCVBUF,
                       (const void *) &rcvbuf, sizeof(int)) == -1) {
            ngx_log_error(NGX_LOG_ALERT, c->log, ngx_socket_errno,
                          "setsockopt(SO_RCVBUF) failed");

            if (ngx_close_socket(s) == -1) {
                ngx_log_error(NGX_LOG_ALERT, c->log, ngx_socket_errno,
                              ngx_close_socket_n " failed");
            }

            return NGX_ERROR;
        }
    }
#endif

    if (ngx_nonblocking(s) == -1) {
        ngx_log_error(NGX_LOG_ALERT, c->log, ngx_socket_errno,
                      ngx_nonblocking_n " failed");

        if (ngx_close_socket(s) == -1) {
            ngx_log_error(NGX_LOG_ALERT, c->log, ngx_socket_errno,
                          ngx_close_socket_n " failed");
        }

        return NGX_ERROR;
    }

    rc = connect(s, (struct sockaddr *) addr, sizeof(struct sockaddr_in));

    if (rc == -1) {
        err = ngx_socket_errno;
        if (err != NGX_EINPROGRESS) {
            ngx_log_error(NGX_LOG_CRIT, c->log, err, "connect() failed");

            if (ngx_close_socket(s) == -1) {
                ngx_log_error(NGX_LOG_ALERT, c->log, ngx_socket_errno,
                              ngx_close_socket_n " failed");
            }

            return NGX_ERROR;
        }
    }

    pc = &ngx_connections[s];
    rev = &ngx_read_events[s];
    wev = &ngx_write_events[s];

    ngx_memzero(rev, sizeof(ngx_event_t));
    ngx_memzero(wev, sizeof(ngx_event_t));
    ngx_memzero(pc, sizeof(ngx_connection_t));

    rev->data = wev->data = pc;
    pc->read = rev;
    pc->write = wev;

    pc->data = r;

    pc->fd = s;
    pc->servers = c->servers;

    pc->log = rev->log = wev->log = c->log;

    ngx_test_null(pc->pool,
                  ngx_create_pool(/* STUB */ 1024 /**/, pc->log),
                  NGX_ERROR);

    wev->event_handler = ngx_http_proxy_send_request;
    rev->event_handler = ngx_http_proxy_read_response_header;

#if (HAVE_CLEAR_EVENT)
    if (ngx_add_event(rev, NGX_READ_EVENT, NGX_CLEAR_EVENT) != NGX_OK) {
#else
    if (ngx_add_event(rev, NGX_READ_EVENT, NGX_LEVEL_EVENT) != NGX_OK) {
#endif
        return NGX_ERROR;
    }

    if (rc == -1) {
        return ngx_add_event(wev, NGX_WRITE_EVENT, NGX_ONESHOT_EVENT);
    }

    wev->write = 1;
    wev->ready = 1;

    return ngx_http_proxy_send_request(wev);
}


static int ngx_http_proxy_send_request(ngx_event_t *ev)
{
    ngx_chain_t           *chain;
    ngx_connection_t      *c;
    ngx_http_request_t    *r;
    ngx_http_proxy_ctx_t  *p;

    c = (ngx_connection_t *) ev->data;
    r = (ngx_http_request_t *) c->data;
    p = (ngx_http_proxy_ctx_t *)
                         ngx_http_get_module_ctx(r, ngx_http_proxy_module_ctx);

    chain = ngx_event_write(c, p->out, 0);
    if (chain == (ngx_chain_t *) -1) {
        return NGX_ERROR;
    }

    p->out = chain;

    return NGX_WAITING;
}


static int ngx_http_proxy_read_response_header(ngx_event_t *ev)
{
    int                    n;
    ngx_hunk_t           **ph;
    ngx_connection_t      *c;
    ngx_http_request_t    *r;
    ngx_http_proxy_ctx_t  *p;

    if (ev->timedout) {
        return NGX_ERROR;
    }

    c = (ngx_connection_t *) ev->data;
    r = (ngx_http_request_t *) c->data;
    p = (ngx_http_proxy_ctx_t *)
                         ngx_http_get_module_ctx(r, ngx_http_proxy_module_ctx);

    if (p->header_in == NULL) {
        ngx_test_null(p->header_in,
                      ngx_create_temp_hunk(r->pool,
                                           /* STUB */ 1024 /**/, 0, 0),
                      NGX_ERROR);

        p->header_in->type = NGX_HUNK_MEMORY;

        ngx_test_null(p->headers_in,
                      ngx_palloc(r->pool, sizeof(ngx_http_proxy_headers_in_t)),
                      NGX_ERROR);

        ngx_init_array(p->hunks, r->pool,
                       /* STUB */ 10 /**/,
                       sizeof(ngx_hunk_t *),
                       NGX_ERROR);

        ngx_test_null(ph, ngx_push_array(&p->hunks), NGX_ERROR);
        *ph = p->header_in;

        p->state_handler = ngx_http_proxy_process_status_line;
    }

    n = ngx_event_recv(c, p->header_in->last.mem,
                       p->header_in->end - p->header_in->last.mem);

    ngx_log_debug(c->log, "READ:%d" _ n);

    p->header_in->last.mem += n;

    /* STUB */
    *p->header_in->last.mem = '\0';
    ngx_log_debug(c->log, "PROXY:\n'%s'" _ p->header_in->pos.mem);
    /**/

    if (n == 0) {
        ngx_log_debug(c->log, "CLOSE proxy");
#if 0
        ngx_del_event(ev, NGX_READ_EVENT, NGX_CLOSE_EVENT);
#endif
        ngx_event_close_connection(ev);

        p->hunk_n = 0;
        c->write->event_handler = ngx_http_proxy_write_to_client;
        return ngx_http_proxy_write_to_client(c->write);
    }

    /* state_handlers are called in following order:
        ngx_http_proxy_process_status_line(r, p)
        ngx_http_proxy_process_reponse_header(r, p) */

#if 0
    do {
        rc = (p->state_handler)(r, p);

        if (rc == NGX_ERROR) {
            return rc;
        }

        /* rc == NGX_OK || rc == NGX_AGAIN */

    } while (p->header_in->pos.mem < p->header_in->last.mem);
#endif

    ev->event_handler = ngx_http_proxy_read_response_body;
    if (p->header_in->end - p->header_in->last.mem == 0) {
        return ngx_http_proxy_read_response_body(ev);
    }

    return NGX_WAITING;
}

static int ngx_http_proxy_process_status_line(ngx_http_request_t *r,
                                              ngx_http_proxy_ctx_t *p)
{
    int  rc;

    rc = ngx_read_http_proxy_status_line(p);

    if (rc == NGX_HTTP_PROXY_PARSE_NO_HEADER) {
        p->status = 200;
    }

    if (rc == NGX_OK) {
        /* STUB */
        ngx_log_debug(r->connection->log, "STATUS: %d" _ p->status);

        p->state_handler = NULL;
    }

    if (p->header_in->last.mem >= p->header_in->end) {
        rc = NGX_HTTP_PARSE_TOO_LONG_STATUS_LINE;

    } else if (rc == NGX_AGAIN) {
        return NGX_AGAIN;
    }

    /* STUB */ return NGX_ERROR;
}

#if 0
static int ngx_http_proxy_process_response_header(ngx_http_request_t *r,
                                                  ngx_http_proxy_ctx_t *p)
{
    return NGX_OK;
}
#endif

static int ngx_http_proxy_read_response_body(ngx_event_t *ev)
{
    int                    n;
    char                  *buf;
    size_t                 left, size;
    ngx_hunk_t            *h, **ph;
    ngx_connection_t      *c;
    ngx_http_request_t    *r;
    ngx_http_proxy_ctx_t  *p;

    if (ev->timedout) {
        return NGX_ERROR;
    }

    c = (ngx_connection_t *) ev->data;
    r = (ngx_http_request_t *) c->data;
    p = (ngx_http_proxy_ctx_t *)
                         ngx_http_get_module_ctx(r, ngx_http_proxy_module_ctx);

    if (p->hunks.nelts > 0) {
        h = ((ngx_hunk_t **) p->hunks.elts)[p->hunks.nelts - 1];
        left = h->end - h->last.mem;

    } else {
        h = NULL;
        left = 0;
    }

    do {

#if (USE_KQUEUE)

        /* do not allocate new block if there is EOF */
        if (ev->eof && ev->available == 0) {
            left = 1;
        }

#elif (HAVE_KQUEUE)

        if (ngx_event_type == NGX_KQUEUE_EVENT) {
            /* do not allocate new block if there is EOF */
            if (ev->eof && ev->available == 0) {
                left = 1;
            }
        }

#endif

        if (left == 0) {
            ngx_test_null(ph, ngx_push_array(&p->hunks), NGX_ERROR);
            ngx_test_null(h,
                          ngx_create_temp_hunk(r->pool,
                                               /* STUB */ 4096 /**/, 0, 0),
                          NGX_ERROR);

            h->type = NGX_HUNK_MEMORY;
            *ph = h;
        }

        if (h != NULL) {
            buf = h->last.mem;
            size = h->end - h->last.mem;

        } else {
            buf = (char *) &buf;
            size = 0;
        }

        n = ngx_event_recv(c, buf, size);

        ngx_log_debug(c->log, "READ:%d" _ n);

        if (n == NGX_AGAIN) {
            return NGX_WAITING;
        }

        if (n == NGX_ERROR) {
            return NGX_ERROR;
        }

        h->last.mem += n;
        left = h->end - h->last.mem;

        /* STUB */
        *h->last.mem = '\0';
        ngx_log_debug(c->log, "PROXY:\n'%s'" _ h->pos.mem);
        /**/

    } while (n > 0 && left == 0);

    if (n == 0) {
        ngx_log_debug(c->log, "CLOSE proxy");
#if 0
        ngx_del_event(ev, NGX_READ_EVENT, NGX_CLOSE_EVENT);
#endif
        ngx_event_close_connection(ev);

        p->hunk_n = 0;
        c->write->event_handler = ngx_http_proxy_write_to_client;
        return ngx_http_proxy_write_to_client(c->write);
    }

    /* STUB */ return NGX_WAITING;
}

static int ngx_http_proxy_write_to_client(ngx_event_t *ev)
{
    int  rc;
    ngx_hunk_t            *h;
    ngx_connection_t      *c;
    ngx_http_request_t    *r;
    ngx_http_proxy_ctx_t  *p;

    c = (ngx_connection_t *) ev->data;
    r = (ngx_http_request_t *) c->data;
    p = (ngx_http_proxy_ctx_t *)
                         ngx_http_get_module_ctx(r, ngx_http_proxy_module_ctx);

    do {
        h = ((ngx_hunk_t **) p->hunks.elts)[p->hunk_n];

        rc = ngx_http_output_filter(r, h);
        if (rc != NGX_OK) {
            return rc;
        }

        if (p->hunk_n >= p->hunks.nelts) {
            break;
        }

        p->hunk_n++;

    } while (rc == NGX_OK);

    return NGX_OK;
}


static int ngx_read_http_proxy_status_line(ngx_http_proxy_ctx_t *ctx)
{
    char   ch;
    char  *p;
    enum  {
        sw_start = 0,
        sw_first_major_digit,
        sw_major_digit,
        sw_first_minor_digit,
        sw_minor_digit,
        sw_status,
        sw_space_after_status,
        sw_status_text,
        sw_almost_done,
        sw_done
    } state;

    state = ctx->state;
    p = ctx->header_in->pos.mem;

    while (p < ctx->header_in->last.mem && state < sw_done) {
        ch = *p++;

#if 0
fprintf(stderr, "state: %d, pos: %x, end: %x, char: '%c', status: %d\n",
        state, p, ctx->header_in->last.mem, ch, ctx->status);
#endif

        switch (state) {

        /* "HTTP/" */
        case sw_start:
            if (p + 3 >= ctx->header_in->last.mem) {
                return NGX_AGAIN;
            }

            if (ch != 'H' || *p != 'T' || *(p + 1) != 'T' || *(p + 2) != 'P'
                          || *(p + 3) != '/')
            {
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }

            p += 4;
            state = sw_first_major_digit;
            break;

        /* first digit of major HTTP version */
        case sw_first_major_digit:
            if (ch < '1' || ch > '9') {
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }

            state = sw_major_digit;
            break;

        /* major HTTP version or dot */
        case sw_major_digit:
            if (ch == '.') {
                state = sw_first_minor_digit;
                break;
            }

            if (ch < '0' || ch > '9') {
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }

            break;

        /* first digit of minor HTTP version */
        case sw_first_minor_digit:
            if (ch < '0' || ch > '9') {
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }

            state = sw_minor_digit;
            break;

        /* minor HTTP version or end of request line */
        case sw_minor_digit:
            if (ch == ' ') {
                state = sw_status;
                break;
            }

            if (ch < '0' || ch > '9') {
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }

            break;

        /* HTTP status code */
        case sw_status:
            if (ch < '0' || ch > '9') {
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }

            ctx->status = ctx->status * 10 + ch - '0';

            if (++ctx->status_count == 3) {
                state = sw_space_after_status;
                ctx->status_line = p - 3;
            }

            break;

         /* space or end of line */
         case sw_space_after_status:
            switch (ch) {
            case ' ':
                state = sw_status_text;
                break;
            case CR:
                state = sw_almost_done;
                break;
            case LF:
                state = sw_done;
                break;
            default:
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }
            break;

        /* any text until end of line */
        case sw_status_text:
            switch (ch) {
            case CR:
                state = sw_almost_done;
                break;
            case LF:
                state = sw_done;
                break;
            }
            break;

        /* end of request line */
        case sw_almost_done:
            ctx->request_end = p - 2;
            switch (ch) {
            case LF:
                state = sw_done;
                break;
            default:
                return NGX_HTTP_PROXY_PARSE_NO_HEADER;
            }
            break;
        }
    }

    ctx->header_in->pos.mem = p;

    if (state == sw_done) {
        if (ctx->request_end == NULL) {
            ctx->request_end = p - 1;
        }

        ctx->state = sw_start;
        return NGX_OK;

    } else {
        ctx->state = state;
        return NGX_AGAIN;
    }
}