/*
 * ngx_http_hello_dolly.c
 */

#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>

static char *ngx_http_hello_dolly(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);

/* commands made available in the location config */
static ngx_command_t ngx_http_hello_dolly_commands[] = {
    {
        ngx_string("hello_dolly"),          // the directive
        NGX_HTTP_LOC_CONF|NGX_CONF_NOARGS,  // lives in a location block, and doesn't take any args
        ngx_http_hello_dolly,               // function callback
        0,                                  // setup
        0,                                  // offset
        NULL,                               //post-processing
    },

    ngx_null_command
};

/* hello dolly contents */
static char *ngx_hello_dolly_strings[] = {
    "Hello, Dolly",
    "It's so nice to have you back where you belong",
    "You're lookin' swell, Dolly",
    "I can tell, Dolly"
};

/* we don't need to define any config handlers */
static ngx_http_module_t ngx_http_hello_dolly_module_ctx = {
    NULL,
    NULL,

    NULL,
    NULL,

    NULL,
    NULL,

    NULL,
    NULL
};

/* expose the module to nginx */
ngx_module_t ngx_http_hello_dolly_module = {
    NGX_MODULE_V1,
    &ngx_http_hello_dolly_module_ctx,   // module context
    ngx_http_hello_dolly_commands,      // module commands
    NGX_HTTP_MODULE,                    // module type
    NULL,                               // more handlers
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NULL,
    NGX_MODULE_V1_PADDING               // lol no idea what the hell this is
};

/* this is where the magic happens */
static ngx_int_t ngx_http_hello_dolly_handler(ngx_http_request_t *r) {
    ngx_int_t rc;
    ngx_buf_t *b;
    ngx_chain_t out;

    // get a random item from the array. yes i know this is a bad way to do it.
    u_char *hello_dolly_str = (u_char *) ngx_hello_dolly_strings[0];

    // respond to GET and HEAD requests only
    if (!(r->method & (NGX_HTTP_GET|NGX_HTTP_HEAD))) {
        return NGX_HTTP_NOT_ALLOWED;
    }

    // discard the request body
    rc = ngx_http_discard_request_body(r);
    if (rc != NGX_OK) {
        return rc;
    }

    // set the Content-Type, Content-Length, and Status headers
    r->headers_out.content_type_len = sizeof("text/plain") - 1;
    r->headers_out.content_type.len = sizeof("text/plain") - 1;
    r->headers_out.content_type.data = (u_char *) "text/plain";

    r->headers_out.content_length_n = sizeof(hello_dolly_str) - 1;
    r->headers_out.status = NGX_HTTP_OK;

    // if this is a HEAD request, just send the header
    if (r->method == NGX_HTTP_HEAD) {
        return ngx_http_send_header(r);
    }

    // allocate a buffer for the response body
    b = ngx_pcalloc(r->pool, sizeof(ngx_buf_t));
    if (b == NULL) {
        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    // attach our buffer to the buffer chain
    out.buf = b;
    out.next = NULL;

    // adjust the buffer pointers
    b->pos = hello_dolly_str;
    b->last = hello_dolly_str + sizeof(hello_dolly_str) - 1;
    b->memory = 1;      // this buffer is in memory
    b->last_buf = 1;    // this is the last buffer in the buffer chain

    rc = ngx_http_send_header(r);

    if (rc == NGX_ERROR || rc > NGX_OK || r->header_only) {
        return rc;
    }

    return ngx_http_output_filter(r, &out);
}

static char *ngx_http_hello_dolly(ngx_conf_t *cf, ngx_command_t *cmd, void *conf) {
    ngx_http_core_loc_conf_t *clcf;

    clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);
    clcf->handler = ngx_http_hello_dolly_handler;

    return NGX_CONF_OK;
}