#include <stdio.h>
#include "ngx_http.c"

#define HELLO_WORLD "hello world\r\n"

static char *ngx_http_hello_world(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
static ngx_int_t ngx_http_hello_world_handler(ngx_http_request_t *r);

/**
 * This module provided directive: hello world.
 *
 */
static ngx_command_t ngx_http_hello_world_commands[] = {

        { ngx_string("hello_world"), /* directive */
          NGX_HTTP_LOC_CONF|NGX_CONF_NOARGS, /* location context and takes
                                            no arguments*/
          ngx_http_hello_world, /* configuration setup function */
          0, /* No offset. Only one context is supported. */
          0, /* No offset when storing the module configuration on struct. */
          NULL},

        ngx_null_command /* command termination */
};

/* The hello world string. */
static u_char ngx_hello_world[] = HELLO_WORLD;

/* The module context. */
static ngx_http_module_t ngx_http_hello_world_module_ctx = {
        NULL, /* preconfiguration */
        NULL, /* postconfiguration */

        NULL, /* create main configuration */
        NULL, /* init main configuration */

        NULL, /* create server configuration */
        NULL, /* merge server configuration */

        NULL, /* create location configuration */
        NULL /* merge location configuration */
};

/* Module definition. */
ngx_module_t ngx_http_hello_world_module = {
        NGX_MODULE_V1,
        &ngx_http_hello_world_module_ctx, /* module context */
        ngx_http_hello_world_commands, /* module directives */
        NGX_HTTP_MODULE, /* module type */
        NULL, /* init master */
        NULL, /* init module */
        NULL, /* init process */
        NULL, /* init thread */
        NULL, /* exit thread */
        NULL, /* exit process */
        NULL, /* exit master */
        NGX_MODULE_V1_PADDING
};

/**
 * Content handler.
 *
 * @param r
 *   Pointer to the request structure. See http_request.h.
 * @return
 *   The status of the response generation.
 */
static ngx_int_t ngx_http_hello_world_handler(ngx_http_request_t *r)
{
    ngx_buf_t *b;
    ngx_chain_t out;

    /* Set the Content-Type header. */
    r->headers_out.content_type.len = sizeof("text/plain") - 1;
    r->headers_out.content_type.data = (u_char *) "text/plain";

    /* Allocate a new buffer for sending out the reply. */
    b = ngx_pcalloc(r->pool, sizeof(ngx_buf_t));

    /* Insertion in the buffer chain. */
    out.buf = b;
    out.next = NULL; /* just one buffer */

    b->pos = ngx_hello_world; /* first position in memory of the data */
    b->last = ngx_hello_world + sizeof(ngx_hello_world) - 1; /* last position in memory of the data */
    b->memory = 1; /* content is in read-only memory */
    b->last_buf = 1; /* there will be no more buffers in the request */

    /* Sending the headers for the reply. */
    r->headers_out.status = NGX_HTTP_OK; /* 200 status code */
    /* Get the content length of the body. */
    r->headers_out.content_length_n = sizeof(ngx_hello_world) - 1;
    ngx_http_send_header(r); /* Send the headers */

    /* Send the body, and return the status code of the output filter chain. */
    return ngx_http_output_filter(r, &out);
} /* ngx_http_hello_world_handler */

/**
 * Configuration setup function that installs the content handler.
 *
 * @param cf
 *   Module configuration structure pointer.
 * @param cmd
 *   Module directives structure pointer.
 * @param conf
 *   Module configuration structure pointer.
 * @return string
 *   Status of the configuration setup.
 */
static char *ngx_http_hello_world(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_core_loc_conf_t *clcf; /* pointer to core location configuration */

    /* Install the hello world handler. */
    clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);
    clcf->handler = ngx_http_hello_world_handler;

    return NGX_CONF_OK;
} /* ngx_http_hello_world */