/*
 *
  ***** BEGIN LICENSE BLOCK *****
 
  Copyright (C) 2009-2019 Olof Hagsand
  Copyright (C) 2020 Olof Hagsand and Rubicon Communications, LLC(Netgate)

  This file is part of CLIXON.

  Licensed under the Apache License, Version 2.0 (the "License");
  you may not use this file except in compliance with the License.
  You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

  Unless required by applicable law or agreed to in writing, software
  distributed under the License is distributed on an "AS IS" BASIS,
  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  See the License for the specific language governing permissions and
  limitations under the License.

  Alternatively, the contents of this file may be used under the terms of
  the GNU General Public License Version 3 or later (the "GPL"),
  in which case the provisions of the GPL are applicable instead
  of those above. If you wish to allow use of your version of this file only
  under the terms of the GPL, and not to allow others to
  use your version of this file under the terms of Apache License version 2, 
  indicate your decision by deleting the provisions above and replace them with
  the  notice and other provisions required by the GPL. If you do not delete
  the provisions above, a recipient may use your version of this file under
  the terms of any one of the Apache License version 2 or the GPL.

  ***** END LICENSE BLOCK *****
  * Generic restconf root handlers eg for /restconf /.well-known, etc
 */


#ifdef HAVE_CONFIG_H
#include "clixon_config.h" /* generated by config & autoconf */
#endif

#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <syslog.h>
#include <fcntl.h>
#include <time.h>
#include <limits.h>
#include <signal.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <libgen.h>
#include <sys/stat.h> /* chmod */

/* cligen */
#include <cligen/cligen.h>

/* clicon */
#include <clixon/clixon.h>

/* restconf */
#include "restconf_lib.h"
#include "restconf_api.h"
#include "restconf_err.h"
#include "restconf_root.h"


/*! Determine the root of the RESTCONF API
 * @param[in]  h        Clicon handle
 * @param[in]  req      Generic Www handle (can be part of clixon handle)
 * @see RFC8040 3.1 and RFC7320
 * In line with the best practices defined by [RFC7320], RESTCONF
 * enables deployments to specify where the RESTCONF API is located.
 */
int
api_well_known(clicon_handle h,
	       void         *req)
{
    int       retval = -1;
    char     *request_method;
    cbuf     *cb = NULL;

    clicon_debug(1, "%s", __FUNCTION__);
    if (req == NULL){
	errno = EINVAL;
	goto done;
    }
    request_method = clixon_restconf_param_get(h, "REQUEST_METHOD");
    if (strcmp(request_method, "GET") != 0){
	restconf_method_notallowed(req, "GET");
	goto ok;
    }
    if (restconf_reply_header(req, "Cache-Control", "no-cache") < 0)
	goto done;
    if (restconf_reply_header(req, "Content-Type", "application/xrd+xml") < 0)
	goto done;
    /* Create body */
    if ((cb = cbuf_new()) == NULL){
	clicon_err(OE_UNIX, errno, "cbuf_new");
	goto done;
    }
    cprintf(cb, "<XRD xmlns='http://docs.oasis-open.org/ns/xri/xrd-1.0'>\n");
    cprintf(cb, "   <Link rel='restconf' href='/restconf'/>\n");
    cprintf(cb, "</XRD>\r\n");

    /* Must be after body */
    if (restconf_reply_header(req, "Content-Length", "%d", cbuf_len(cb)) < 0)
	goto done;
    if (restconf_reply_send(req, 200, cb) < 0)
	goto done;
 ok:
    retval = 0;
 done:
    if (cb)
	cbuf_free(cb);
    return retval;
}

/*! Retrieve the Top-Level API Resource
 * @param[in]  h        Clicon handle
 * @param[in]  r        Fastcgi request handle
 * @note Only returns null for operations and data,...
 * See RFC8040 3.3
 * XXX doesnt check method
 */
static int
api_root(clicon_handle  h,
	 void          *req,
	 char          *request_method,
	 int            pretty,
	 restconf_media media_out)

{
    int        retval = -1;
    yang_stmt *yspec;
    cxobj     *xt = NULL;
    cbuf      *cb = NULL;

    clicon_debug(1, "%s", __FUNCTION__);
    if (strcmp(request_method, "GET") != 0){
	restconf_method_notallowed(req, "GET");
	goto ok;
    }
    if ((yspec = clicon_dbspec_yang(h)) == NULL){
	clicon_err(OE_FATAL, 0, "No DB_SPEC");
	goto done;
    }
    if (restconf_reply_header(req, "Cache-Control", "no-cache") < 0)
	goto done;
    if (restconf_reply_header(req, "Content-Type", "%s", restconf_media_int2str(media_out)) < 0)
	goto done;
    
    if (clixon_xml_parse_string("<restconf xmlns=\"urn:ietf:params:xml:ns:yang:ietf-restconf\"><data/>"
				"<operations/><yang-library-version>2016-06-21</yang-library-version></restconf>",
				YB_MODULE, yspec, &xt, NULL) < 0)
	goto done;

    if ((cb = cbuf_new()) == NULL){
	clicon_err(OE_XML, errno, "cbuf_new");
	goto done;
    }
    if (xml_rootchild(xt, 0, &xt) < 0)
	goto done;
    switch (media_out){
    case YANG_DATA_XML:
	if (clicon_xml2cbuf(cb, xt, 0, pretty, -1) < 0)
	    goto done;
	break;
    case YANG_DATA_JSON:
	if (xml2json_cbuf(cb, xt, pretty) < 0)
	    goto done;
	break;
    default:
	break;
    }
    if (restconf_reply_header(req, "Content-Length", "%d", cbuf_len(cb)) < 0)
	goto done;
    if (restconf_reply_send(req, 200, cb) < 0)
	goto done;
 ok:
    retval = 0;
 done:
    if (cb)
        cbuf_free(cb);
    if (xt)
	xml_free(xt);
    return retval;
}

/*!
 * See https://tools.ietf.org/html/rfc7895
 */
static int
api_yang_library_version(clicon_handle h,
			 void         *req,
			 int           pretty,
			 restconf_media media_out)
    
{
#if 1
    clicon_debug(1, "%s", __FUNCTION__);
    return 0;
#else
    int    retval = -1;
    cxobj *xt = NULL;
    cbuf  *cb = NULL;
    char  *ietf_yang_library_revision = "2016-06-21"; /* XXX */

    clicon_debug(1, "%s", __FUNCTION__);
    FCGX_SetExitStatus(200, r->out); /* OK */
    FCGX_FPrintF(r->out, "Cache-Control: no-cache\r\n");
    FCGX_FPrintF(r->out, "Content-Type: %s\r\n", restconf_media_int2str(media_out));
    FCGX_FPrintF(r->out, "\r\n");
    if (clixon_xml_parse_va(YB_NONE, NULL, &xt, NULL,
			    "<yang-library-version>%s</yang-library-version>",
			    ietf_yang_library_revision) < 0)
	goto done;
    if (xml_rootchild(xt, 0, &xt) < 0)
	goto done;
    if ((cb = cbuf_new()) == NULL){
	goto done;
    }
    switch (media_out){
    case YANG_DATA_XML:
	if (clicon_xml2cbuf(cb, xt, 0, pretty, -1) < 0)
	    goto done;
	break;
    case YANG_DATA_JSON:
	if (xml2json_cbuf(cb, xt, pretty) < 0)
	    goto done;
	break;
    default:
	break;
    }
    clicon_debug(1, "%s cb%s", __FUNCTION__, cbuf_get(cb));
    FCGX_FPrintF(r->out, "%s\n", cb?cbuf_get(cb):"");
    FCGX_FPrintF(r->out, "\n\n");
    retval = 0;
 done:
    if (cb)
        cbuf_free(cb);
    if (xt)
	xml_free(xt);
    return retval;
#endif
}

/*! Generic REST method, GET, PUT, DELETE, etc
 * @param[in]  h      CLIXON handle
 * @param[in]  r      Fastcgi request handle
 * @param[in]  api_path According to restconf (Sec 3.5.1.1 in [draft])
 * @param[in]  pcvec  Vector of path ie DOCUMENT_URI element
 * @param[in]  pi     Offset, where to start pcvec
 * @param[in]  qvec   Vector of query string (QUERY_STRING)
 * @param[in]  pretty Set to 1 for pretty-printed xml/json output
 * @param[in]  media_in  Input media
 * @param[in]  media_out Output media
 */
static int
api_data(clicon_handle h,
	 void         *req, 
	 char         *api_path, 
	 cvec         *pcvec, 
	 int           pi,
	 cvec         *qvec, 
	 char         *data,
	 int           pretty,
	 restconf_media media_out)
{
#if 1
    clicon_debug(1, "%s", __FUNCTION__);
    return 0;
#else
    int     retval = -1;
    char   *request_method;

    clicon_debug(1, "%s", __FUNCTION__);
    request_method = clixon_restconf_param_get(h, "REQUEST_METHOD");
    clicon_debug(1, "%s method:%s", __FUNCTION__, request_method);
    if (strcmp(request_method, "OPTIONS")==0)
	retval = api_data_options(h, req);
    else if (strcmp(request_method, "HEAD")==0)
	retval = api_data_head(h, req, api_path, pcvec, pi, qvec, pretty, media_out);
    else if (strcmp(request_method, "GET")==0)
	retval = api_data_get(h, req, api_path, pcvec, pi, qvec, pretty, media_out);
    else if (strcmp(request_method, "POST")==0)
	retval = api_data_post(h, req, api_path, pi, qvec, data, pretty, media_out);
    else if (strcmp(request_method, "PUT")==0)
	retval = api_data_put(h, req, api_path, pcvec, pi, qvec, data, pretty, media_out);
    else if (strcmp(request_method, "PATCH")==0)
	retval = api_data_patch(h, req, api_path, pcvec, pi, qvec, data, pretty, media_out);
    else if (strcmp(request_method, "DELETE")==0)
	retval = api_data_delete(h, req, api_path, pi, pretty, media_out);
    else
	retval = restconf_notfound(h, req);
    clicon_debug(1, "%s retval:%d", __FUNCTION__, retval);
    return retval;
#endif
}

/*! Move back to restconf_methods_get
 */
static int
api_operations_get(clicon_handle h,
		   void         *req, 
		   char         *path, 
		   int           pi,
		   cvec         *qvec, 
		   char         *data,
		   int           pretty,
		   restconf_media media_out)
{
    int        retval = -1;
    yang_stmt *yspec;
    yang_stmt *ymod; /* yang module */
    yang_stmt *yc;
    char      *namespace;
    cbuf      *cb = NULL;
    cxobj     *xt = NULL;
    int        i;
    
    clicon_debug(1, "%s", __FUNCTION__);
    yspec = clicon_dbspec_yang(h);
    if ((cb = cbuf_new()) == NULL){
	clicon_err(OE_UNIX, errno, "cbuf_new");
	goto done;
    }
    switch (media_out){
    case YANG_DATA_XML:
	cprintf(cb, "<operations>");
	break;
    case YANG_DATA_JSON:
	if (pretty)
	    cprintf(cb, "{\"operations\": {\n");
	else
	    cprintf(cb, "{\"operations\":{");
	break;
    default:
	break;
    }
    ymod = NULL;
    i = 0;
    while ((ymod = yn_each(yspec, ymod)) != NULL) {
	namespace = yang_find_mynamespace(ymod);
	yc = NULL; 
	while ((yc = yn_each(ymod, yc)) != NULL) {
	    if (yang_keyword_get(yc) != Y_RPC)
		continue;
	    switch (media_out){
	    case YANG_DATA_XML:
		cprintf(cb, "<%s xmlns=\"%s\"/>", yang_argument_get(yc), namespace);
		break;
	    case YANG_DATA_JSON:
		if (i++){
		    cprintf(cb, ",");
		    if (pretty)
			cprintf(cb, "\n\t");
		}
		if (pretty)
		    cprintf(cb, "\"%s:%s\": [null]", yang_argument_get(ymod), yang_argument_get(yc));
		else
		    cprintf(cb, "\"%s:%s\":[null]", yang_argument_get(ymod), yang_argument_get(yc));
		break;
	    default:
		break;
	    }
	}
    }
    switch (media_out){
    case YANG_DATA_XML:
	cprintf(cb, "</operations>");
	break;
    case YANG_DATA_JSON:
	if (pretty)
	    cprintf(cb, "}\n}");
	else
	    cprintf(cb, "}}");
	break;
    default:
	break;
    }
    if (restconf_reply_header(req, "Content-Type", "%s", restconf_media_int2str(media_out)) < 0)
	goto done;
    if (restconf_reply_header(req, "Content-Length", "%d", cbuf_len(cb)) < 0)
	goto done;
    if (restconf_reply_send(req, 200, cb) < 0)
	goto done;
    retval = 0;
 done:
    clicon_debug(1, "%s retval:%d", __FUNCTION__, retval);
    if (cb)
        cbuf_free(cb);
    if (xt)
	xml_free(xt);
    return retval;
}

/*! Operations REST method, POST
 * @param[in]  h      CLIXON handle
 * @param[in]  req   Generic Www handle (can be part of clixon handle)
 * @param[in]  request_method  eg GET,...
 * @param[in]  path   According to restconf (Sec 3.5.1.1 in [draft])
 * @param[in]  pcvec  Vector of path ie DOCUMENT_URI element
 * @param[in]  pi     Offset, where to start pcvec
 * @param[in]  qvec   Vector of query string (QUERY_STRING)
 * @param[in]  data   Stream input data
 * @param[in]  media_out Output media
 */
static int
api_operations(clicon_handle h,
	       void         *req, 
	       char         *request_method,
	       char         *path,
	       cvec         *pcvec, 
	       int           pi,
	       cvec         *qvec, 
	       char         *data,
	       int           pretty,
	       restconf_media media_out)
{
    int retval;

    clicon_debug(1, "%s", __FUNCTION__);
    if (strcmp(request_method, "GET")==0)
	retval = api_operations_get(h, req, path, pi, qvec, data, pretty, media_out);
#ifdef NYI
    else if (strcmp(request_method, "POST")==0)
	retval = api_operations_post(h, req, path, pi, qvec, data,
				     pretty, media_out);
#endif
    else
	retval = restconf_notfound(h, req);
    return retval;
}

/*! Process a /restconf root input, this is the root of the restconf processing
 * @param[in]  h     Clicon handle
 * @param[in]  req   Generic Www handle (can be part of clixon handle)
 * @param[in]  qvec  Query parameters, ie the ?<id>=<val>&<id>=<val> stuff
 */
int
api_root_restconf(clicon_handle h,
		  void         *req,
		  cvec         *qvec)
{
    int            retval = -1;
    char          *request_method = NULL; /* GET,.. */
    char          *api_resource = NULL;   /* RFC8040 3.3: eg data/operations */
    char          *path;
    char         **pvec = NULL;
    cvec          *pcvec = NULL; /* for rest api */
    int            pn;
    int            pretty;
    cbuf          *cb = NULL;
    char          *media_str = NULL;
    restconf_media media_out = YANG_DATA_JSON;
    char          *indata = NULL;
    int            authenticated = 0;
    cxobj         *xret = NULL;
    cxobj         *xerr;

    clicon_debug(1, "%s", __FUNCTION__);
    if (req == NULL){
	errno = EINVAL;
	goto done;
    }
    request_method = clixon_restconf_param_get(h, "REQUEST_METHOD");
    path = restconf_uripath(h);
    pretty = clicon_option_bool(h, "CLICON_RESTCONF_PRETTY");
    /* Get media for output (proactive negotiation) RFC7231 by using
     * Accept:. This is for methods that have output, such as GET, 
     * operation POST, etc
     * If accept is * default is yang-json
     */
    if ((media_str = clixon_restconf_param_get(h, "HTTP_ACCEPT")) == NULL){
	// retval = restconf_unsupported_media(r);
	// goto done;
    }
    else    if ((int)(media_out = restconf_media_str2int(media_str)) == -1){
	if (strcmp(media_str, "*/*") == 0) /* catch-all */
	    media_out = YANG_DATA_JSON;
	else{
	    retval = restconf_unsupported_media(req);
	    goto done;
	}
    }


    clicon_debug(1, "%s ACCEPT: %s %s", __FUNCTION__, media_str, restconf_media_int2str(media_out));

    if ((pvec = clicon_strsep(path, "/", &pn)) == NULL)
	goto done;
    /* Sanity check of path. Should be /restconf/ */
    if (pn < 2){
	restconf_notfound(h, req);
	goto ok;
    }
    if (strlen(pvec[0]) != 0){
	retval = restconf_notfound(h, req);
	goto done;
    }
    if (strcmp(pvec[1], RESTCONF_API)){
	retval = restconf_notfound(h, req);
	goto done;
    }
    if (pn == 2){
	retval = api_root(h, req, request_method, pretty, media_out);
	goto done;
    }
    if ((api_resource = pvec[2]) == NULL){
	retval = restconf_notfound(h, req);
	goto done;
    }
    clicon_debug(1, "%s: api_resource=%s", __FUNCTION__, api_resource);
    if (str2cvec(path, '/', '=', &pcvec) < 0) /* rest url eg /album=ricky/foo */
      goto done;
    /* data */
    if ((cb = restconf_get_indata(req)) == NULL) /* XXX NYI ACTUALLY not always needed, do this later? */
	goto done;
    indata = cbuf_get(cb);
    clicon_debug(1, "%s DATA=%s", __FUNCTION__, indata);

    /* If present, check credentials. See "plugin_credentials" in plugin  
     * See RFC 8040 section 2.5
     */
    if ((authenticated = clixon_plugin_auth_all(h, req)) < 0)
	goto done;
    clicon_debug(1, "%s auth:%d %s", __FUNCTION__, authenticated, clicon_username_get(h));

    /* If set but no user, set a dummy user */
    if (authenticated){
	if (clicon_username_get(h) == NULL)
	    clicon_username_set(h, "none");
    }
    else{
	if (netconf_access_denied_xml(&xret, "protocol", "The requested URL was unauthorized") < 0)
	    goto done;
	if ((xerr = xpath_first(xret, NULL, "//rpc-error")) != NULL){
	    if (api_return_err(h, req, xerr, pretty, media_out, 0) < 0)
		goto done;
	    goto ok;
	}
	goto ok;
    }
    clicon_debug(1, "%s auth2:%d %s", __FUNCTION__, authenticated, clicon_username_get(h));
    if (strcmp(api_resource, "yang-library-version")==0){
	if (api_yang_library_version(h, req, pretty, media_out) < 0) /* XXX NYI */
	    goto done;
    }
    else if (strcmp(api_resource, "data") == 0){ /* restconf, skip /api/data */ /* XXX NYI */
	if (api_data(h, req, path, pcvec, 2, qvec, indata,
		     pretty, media_out) < 0)
	    goto done;
    }
    else if (strcmp(api_resource, "operations") == 0){ /* rpc */
	if (api_operations(h, req, request_method, path, pcvec, 2, qvec, indata, 
			   pretty, media_out) < 0)
	    goto done;
    }
    else
	restconf_notfound(h, req);
 ok:
    retval = 0;
 done:
    clicon_debug(1, "%s retval:%d", __FUNCTION__, retval);
    if (pcvec)
	cvec_free(pcvec);
    if (pvec)
	free(pvec);
    if (cb)
	cbuf_free(cb);
    if (xret)
	xml_free(xret);
    return retval;
}