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


typedef struct {
    ngx_array_t  indices;
    size_t       max_index_len;
} ngx_http_index_conf_t;


typedef struct {
    int          index;
    unsigned     tested:1;
} ngx_http_index_ctx_t;


#define NGX_HTTP_DEFAULT_INDEX   "index.html"


static int ngx_http_index_test_dir(ngx_http_request_t *r,
                                   ngx_http_index_ctx_t *ctx);
static int ngx_http_index_error(ngx_http_request_t *r,
                                ngx_http_index_ctx_t *ctx, ngx_err_t err);

static int ngx_http_index_init(ngx_cycle_t *cycle);
static void *ngx_http_index_create_conf(ngx_conf_t *cf);
static char *ngx_http_index_merge_conf(ngx_conf_t *cf,
                                       void *parent, void *child);
static char *ngx_http_index_set_index(ngx_conf_t *cf, ngx_command_t *cmd,
                                      void *conf);


static ngx_command_t ngx_http_index_commands[] = {

    {ngx_string("index"),
     NGX_HTTP_LOC_CONF|NGX_CONF_1MORE,
     ngx_http_index_set_index,
     NGX_HTTP_LOC_CONF_OFFSET,
     0,
     NULL},

    ngx_null_command
};


ngx_http_module_t  ngx_http_index_module_ctx = {
    NULL,                                  /* pre conf */

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

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

    ngx_http_index_create_conf,            /* create location configration */
    ngx_http_index_merge_conf              /* merge location configration */
};


ngx_module_t  ngx_http_index_module = {
    NGX_MODULE,
    &ngx_http_index_module_ctx,            /* module context */
    ngx_http_index_commands,               /* module directives */
    NGX_HTTP_MODULE,                       /* module type */
    ngx_http_index_init,                   /* init module */
    NULL                                   /* init child */
};


/*
 * Try to open the first index file before the test of the directory existence
 * because the valid requests should be many more than invalid ones.
 * If open() failed then stat() should be more quickly because some data
 * is already cached in the kernel.
 * Besides Win32 has ERROR_PATH_NOT_FOUND (NGX_ENOTDIR).
 * Unix has ENOTDIR error, although it less helpfull - it shows only
 * that path contains the usual file in place of the directory.
 */

int ngx_http_index_handler(ngx_http_request_t *r)
{
    int                        rc;
    char                      *name, *file;
    ngx_str_t                  redirect, *index;
    ngx_err_t                  err;
    ngx_fd_t                   fd;
    ngx_http_index_ctx_t      *ctx;
    ngx_http_index_conf_t     *icf;
    ngx_http_core_loc_conf_t  *clcf;

    if (r->uri.data[r->uri.len - 1] != '/') {
        return NGX_DECLINED;
    }

    ctx = ngx_http_get_module_ctx(r, ngx_http_index_module);
    if (ctx == NULL) {
        ngx_http_create_ctx(r, ctx, ngx_http_index_module,
                            sizeof(ngx_http_index_ctx_t),
                            NGX_HTTP_INTERNAL_SERVER_ERROR);
    }

    icf = ngx_http_get_module_loc_conf(r, ngx_http_index_module);
    clcf = ngx_http_get_module_loc_conf(r, ngx_http_core_module);

    if (r->path.data == NULL) {
        r->path_allocated = clcf->doc_root.len + r->uri.len
                                                          + icf->max_index_len;
        ngx_test_null(r->path.data,
                      ngx_palloc(r->pool, r->path_allocated),
                      NGX_HTTP_INTERNAL_SERVER_ERROR);

        redirect.data = ngx_cpymem(r->path.data, clcf->doc_root.data,
                                   clcf->doc_root.len);
        file = ngx_cpystrn(redirect.data, r->uri.data, r->uri.len + 1);
        r->path.len = file - r->path.data;

    } else{
        redirect.data = r->path.data + r->path.len;
        file = redirect.data + r->uri.len;
    }

    index = icf->indices.elts;
    for (/* void */; ctx->index < icf->indices.nelts; ctx->index++) {

        if (index[ctx->index].data[0] == '/') {
            name = index[ctx->index].data;

        } else {
            ngx_memcpy(file, index[ctx->index].data, index[ctx->index].len + 1);
            name = r->path.data;
        }

        fd = ngx_open_file(name, NGX_FILE_RDONLY, NGX_FILE_OPEN);

        if (fd == (ngx_fd_t) NGX_AGAIN) {
            return NGX_AGAIN;
        }

        if (fd == NGX_INVALID_FILE) {
            err = ngx_errno;

ngx_log_error(NGX_LOG_DEBUG, r->connection->log, err,
              "DEBUG: " ngx_open_file_n " %s failed", name);

            if (err == NGX_ENOTDIR) {
                return ngx_http_index_error(r, ctx, err);

            } else if (err == NGX_EACCES) {
                return ngx_http_index_error(r, ctx, err);
            }

            if (!ctx->tested) {
                rc = ngx_http_index_test_dir(r, ctx);

                if (rc != NGX_OK) {
                    return rc;
                }

                ctx->tested = 1;
            }

            if (err == NGX_ENOENT) {
                continue;
            }

            ngx_log_error(NGX_LOG_ERR, r->connection->log, err,
                          ngx_open_file_n " %s failed", name);

            return NGX_HTTP_INTERNAL_SERVER_ERROR;
        }

        r->file.name.data = name;
        r->file.fd = fd;

        if (index[ctx->index].data[0] == '/') {
            r->file.name.len = index[ctx->index].len;
            redirect.len = index[ctx->index].len;
            redirect.data = index[ctx->index].data;

        } else {
            redirect.len = r->uri.len + index[ctx->index].len;
            r->file.name.len = clcf->doc_root.len + r->uri.len
                                                       + index[ctx->index].len;
        }

        return ngx_http_internal_redirect(r, &redirect, NULL);
    }

    return NGX_DECLINED;
}


static int ngx_http_index_test_dir(ngx_http_request_t *r,
                                   ngx_http_index_ctx_t *ctx)
{
    ngx_err_t  err;

    r->path.data[r->path.len - 1] = '\0';
    r->path.data[r->path.len] = '\0';

ngx_log_debug(r->connection->log, "IS_DIR: %s" _ r->path.data);

    if (ngx_file_info(r->path.data, &r->file.info) == -1) {

        err = ngx_errno;

        if (err == NGX_ENOENT) {
            r->path.data[r->path.len - 1] = '/';
            return ngx_http_index_error(r, ctx, err);
        }

        ngx_log_error(NGX_LOG_CRIT, r->connection->log, err,
                      ngx_file_info_n " %s failed", r->path.data);

        return NGX_HTTP_INTERNAL_SERVER_ERROR;
    }

    r->path.data[r->path.len - 1] = '/';

    if (ngx_is_dir(&r->file.info)) {
        return NGX_OK;
    }

    /* THINK: not reached ??? */
    return ngx_http_index_error(r, ctx, 0);
}


static int ngx_http_index_error(ngx_http_request_t *r,
                                ngx_http_index_ctx_t *ctx, ngx_err_t err)
{
    if (err == NGX_EACCES) {
        ngx_log_error(NGX_LOG_ERR, r->connection->log, err,
                      "\"%s\" is forbidden", r->path.data);
    
        return NGX_HTTP_FORBIDDEN;
    }

    ngx_log_error(NGX_LOG_ERR, r->connection->log, err,
                  "\"%s\" is not found", r->path.data);
    return NGX_HTTP_NOT_FOUND;
}


static int ngx_http_index_init(ngx_cycle_t *cycle)
{
    ngx_http_handler_pt        *h;
    ngx_http_conf_ctx_t        *ctx;
    ngx_http_core_main_conf_t  *cmcf;

    ctx = (ngx_http_conf_ctx_t *) cycle->conf_ctx[ngx_http_module.index];
    cmcf = ctx->main_conf[ngx_http_core_module.ctx_index];

    ngx_test_null(h, ngx_push_array(
                             &cmcf->phases[NGX_HTTP_TRANSLATE_PHASE].handlers),
                  NGX_ERROR);
    *h = ngx_http_index_handler;

    return NGX_OK;
}


static void *ngx_http_index_create_conf(ngx_conf_t *cf)
{
    ngx_http_index_conf_t  *conf;

    ngx_test_null(conf, ngx_palloc(cf->pool, sizeof(ngx_http_index_conf_t)),
                  NGX_CONF_ERROR);

    ngx_init_array(conf->indices, cf->pool, 3, sizeof(ngx_str_t),
                   NGX_CONF_ERROR);
    conf->max_index_len = 0;

    return conf;
}


/* TODO: remove duplicate indices */

static char *ngx_http_index_merge_conf(ngx_conf_t *cf,
                                       void *parent, void *child)
{
    ngx_http_index_conf_t *prev = parent;
    ngx_http_index_conf_t *conf = child;

    int         i;
    ngx_str_t  *index, *prev_index;

    if (conf->max_index_len == 0) {
        if (prev->max_index_len != 0) {
            ngx_memcpy(conf, prev, sizeof(ngx_http_index_conf_t));
            return NGX_CONF_OK;
        }

        ngx_test_null(index, ngx_push_array(&conf->indices), NGX_CONF_ERROR);
        index->len = sizeof(NGX_HTTP_DEFAULT_INDEX) - 1;
        index->data = NGX_HTTP_DEFAULT_INDEX;
        conf->max_index_len = sizeof(NGX_HTTP_DEFAULT_INDEX);

        return NGX_CONF_OK;
    }

    if (prev->max_index_len != 0) {

        prev_index = prev->indices.elts;
        for (i = 0; i < prev->indices.nelts; i++) {
            ngx_test_null(index, ngx_push_array(&conf->indices),
                          NGX_CONF_ERROR);
            index->len = prev_index[i].len;
            index->data = prev_index[i].data;
        }
    }

    if (conf->max_index_len < prev->max_index_len) {
        conf->max_index_len = prev->max_index_len;
    }

    return NGX_CONF_OK;
}


/* TODO: warn about duplicate indices */

static char *ngx_http_index_set_index(ngx_conf_t *cf, ngx_command_t *cmd,
                                      void *conf)
{
    ngx_http_index_conf_t *icf = conf;

    int         i;
    ngx_str_t  *index, *value;

    value = cf->args->elts;

    if (value[1].data[0] == '/' && icf->indices.nelts == 0) {
        ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                           "first index \"%s\" in \"%s\" directive "
                           "must not be absolute",
                           value[1].data, cmd->name.data);
        return NGX_CONF_ERROR;
    }

    for (i = 1; i < cf->args->nelts; i++) {
        if (value[i].len == 0) {
            ngx_conf_log_error(NGX_LOG_EMERG, cf, 0,
                               "index \"%s\" in \"%s\" directive is invalid",
                               value[1].data, cmd->name.data);
            return NGX_CONF_ERROR;
        }

        ngx_test_null(index, ngx_push_array(&icf->indices), NGX_CONF_ERROR);
        index->len = value[i].len;
        index->data = value[i].data;

        if (icf->max_index_len < index->len + 1) {
            icf->max_index_len = index->len + 1;
        }
    }

    return NGX_CONF_OK;
}