/*
 * Copyright 2016 IoT.bzh
 * Author: José Bollo <jose.bollo@iot.bzh>
 *
 * 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.
 */

#define _GNU_SOURCE
#include <microhttpd.h>
#include <assert.h>
#include <poll.h>
#include <sys/stat.h>

#include "../include/local-def.h"
#include "afb-method.h"
#include "afb-hreq.h"
#include "afb-websock.h"


struct afb_hsrv_handler {
	struct afb_hsrv_handler *next;
	const char *prefix;
	size_t length;
	int (*handler) (struct afb_hreq *, struct afb_hreq_post *, void *);
	void *data;
	int priority;
};

struct afb_diralias {
	const char *alias;
	const char *directory;
	size_t lendir;
	int dirfd;
};

int afb_hreq_one_page_api_redirect(
		struct afb_hreq *hreq,
		struct afb_hreq_post *post,
		void *data)
{
	size_t plen;
	char *url;

	if (hreq->lentail >= 2 && hreq->tail[1] == '#')
		return 0;
	/*
	 * Here we have for example:
	 *    url  = "/pre/dir/page"   lenurl = 13
	 *    tail =     "/dir/page"   lentail = 9
	 *
	 * We will produce "/pre/#!dir/page"
	 *
	 * Let compute plen that include the / at end (for "/pre/")
	 */
	plen = hreq->lenurl - hreq->lentail + 1;
	url = alloca(hreq->lenurl + 3);
	memcpy(url, hreq->url, plen);
	url[plen++] = '#';
	url[plen++] = '!';
	memcpy(&url[plen], &hreq->tail[1], hreq->lentail);
	return afb_hreq_redirect_to(hreq, url);
}

struct afb_hsrv_handler *afb_hsrv_handler_new(
		struct afb_hsrv_handler *head,
		const char *prefix,
		int (*handler) (struct afb_hreq *, struct afb_hreq_post *, void *),
		void *data,
		int priority)
{
	struct afb_hsrv_handler *link, *iter, *previous;
	size_t length;

	/* get the length of the prefix without its leading / */
	length = strlen(prefix);
	while (length && prefix[length - 1] == '/')
		length--;

	/* allocates the new link */
	link = malloc(sizeof *link);
	if (link == NULL)
		return NULL;

	/* initialize it */
	link->prefix = prefix;
	link->length = length;
	link->handler = handler;
	link->data = data;
	link->priority = priority;

	/* adds it */
	previous = NULL;
	iter = head;
	while (iter && (priority < iter->priority || (priority == iter->priority && length <= iter->length))) {
		previous = iter;
		iter = iter->next;
	}
	link->next = iter;
	if (previous == NULL)
		return link;
	previous->next = link;
	return head;
}

int afb_req_add_handler(
		AFB_session * session,
		const char *prefix,
		int (*handler) (struct afb_hreq *, struct afb_hreq_post *, void *),
		void *data,
		int priority)
{
	struct afb_hsrv_handler *head;

	head = afb_hsrv_handler_new(session->handlers, prefix, handler, data, priority);
	if (head == NULL)
		return 0;
	session->handlers = head;
	return 1;
}

static int relay_to_doRestApi(struct afb_hreq *hreq, struct afb_hreq_post *post, void *data)
{
	int later;
	if (afb_websock_check(hreq, &later)) {
		if (!later) {
			struct afb_websock *ws = afb_websock_create(hreq->connection);
		}
		return 1;
	}

	return doRestApi(hreq->connection, hreq->session, &hreq->tail[1], get_method_name(hreq->method),
			 post->upload_data, post->upload_data_size, (void **)hreq->recorder);
}

static int handle_alias(struct afb_hreq *hreq, struct afb_hreq_post *post, void *data)
{
	struct afb_diralias *da = data;

	if (hreq->method != afb_method_get) {
		afb_hreq_reply_error(hreq, MHD_HTTP_METHOD_NOT_ALLOWED);
		return 1;
	}

	if (!afb_hreq_valid_tail(hreq)) {
		afb_hreq_reply_error(hreq, MHD_HTTP_FORBIDDEN);
		return 1;
	}

	return afb_hreq_reply_file(hreq, da->dirfd, &hreq->tail[1]);
}

int afb_req_add_alias(AFB_session * session, const char *prefix, const char *alias, int priority)
{
	struct afb_diralias *da;
	int dirfd;

	dirfd = open(alias, O_PATH|O_DIRECTORY);
	if (dirfd < 0) {
		/* TODO message */
		return 0;
	}
	da = malloc(sizeof *da);
	if (da != NULL) {
		da->alias = prefix;
		da->directory = alias;
		da->lendir = strlen(da->directory);
		da->dirfd = dirfd;
		if (afb_req_add_handler(session, prefix, handle_alias, da, priority))
			return 1;
		free(da);
	}
	close(dirfd);
	return 0;
}

static int my_default_init(AFB_session * session)
{
	int idx;

	if (!afb_req_add_handler(session, session->config->rootapi, relay_to_doRestApi, NULL, 1))
		return 0;

	for (idx = 0; session->config->aliasdir[idx].url != NULL; idx++)
		if (!afb_req_add_alias
		    (session, session->config->aliasdir[idx].url, session->config->aliasdir[idx].path, 0))
			return 0;

	if (!afb_req_add_alias(session, "", session->config->rootdir, -10))
		return 0;

	if (!afb_req_add_handler(session, session->config->rootbase, afb_hreq_one_page_api_redirect, NULL, -20))
		return 0;

	return 1;
}

static int access_handler(
		void *cls,
		struct MHD_Connection *connection,
		const char *url,
		const char *methodstr,
		const char *version,
		const char *upload_data,
		size_t * upload_data_size,
		void **recorder)
{
	struct afb_hreq_post post;
	struct afb_hreq hreq;
	enum afb_method method;
	AFB_session *session;
	struct afb_hsrv_handler *iter;

	session = cls;
	post.upload_data = upload_data;
	post.upload_data_size = upload_data_size;

#if 0
	struct afb_hreq *previous;

	previous = *recorder;
	if (previous) {
		assert((void **)previous->recorder == recorder);
		assert(previous->session == session);
		assert(previous->connection == connection);
		assert(previous->method == get_method(methodstr));
		assert(previous->url == url);

		/* TODO */
/*
		assert(previous->post_handler != NULL);
		previous->post_handler(previous, &post);
		return MHD_NO;
*/
	}
#endif

	method = get_method(methodstr);
	if (method == afb_method_none) {
		afb_hreq_reply_error(&hreq, MHD_HTTP_BAD_REQUEST);
		return MHD_YES;
	}

	/* init the request */
	hreq.session = cls;
	hreq.connection = connection;
	hreq.method = method;
	hreq.version = version;
	hreq.tail = hreq.url = url;
	hreq.lentail = hreq.lenurl = strlen(url);
	hreq.recorder = (struct afb_hreq **)recorder;
	hreq.post_handler = NULL;
	hreq.post_completed = NULL;
	hreq.post_data = NULL;

	/* search an handler for the request */
	iter = session->handlers;
	while (iter) {
		if (afb_hreq_unprefix(&hreq, iter->prefix, iter->length)) {
			if (iter->handler(&hreq, &post, iter->data))
				return MHD_YES;
			hreq.tail = hreq.url;
			hreq.lentail = hreq.lenurl;
		}
		iter = iter->next;
	}

	/* no handler */
	afb_hreq_reply_error(&hreq, method != afb_method_get ? MHD_HTTP_BAD_REQUEST : MHD_HTTP_NOT_FOUND);
	return MHD_YES;
}

/* Because of POST call multiple time requestApi we need to free POST handle here */
static void end_handler(void *cls, struct MHD_Connection *connection, void **con_cls,
			enum MHD_RequestTerminationCode toe)
{
	AFB_PostHandle *posthandle = *con_cls;

	/* if post handle was used let's free everything */
	if (posthandle != NULL)
		endPostRequest(posthandle);
}

static int new_client_handler(void *cls, const struct sockaddr *addr, socklen_t addrlen)
{
	return MHD_YES;
}

#if defined(USE_MAGIC_MIME_TYPE)

#if !defined(MAGIC_DB)
#define MAGIC_DB "/usr/share/misc/magic.mgc"
#endif

static int init_lib_magic (AFB_session *session)
{
	/* MAGIC_MIME tells magic to return a mime of the file, but you can specify different things */
	if (verbose)
		printf("Loading mimetype default magic database\n");

	session->magic = magic_open(MAGIC_MIME_TYPE);
	if (session->magic == NULL) {
		fprintf(stderr,"ERROR: unable to initialize magic library\n");
		return 0;
	}

	/* Warning: should not use NULL for DB [libmagic bug wont pass efence check] */
	if (magic_load(session->magic, MAGIC_DB) != 0) {
		fprintf(stderr,"cannot load magic database - %s\n", magic_error(session->magic));
/*
		magic_close(session->magic);
		session->magic = NULL;
		return 0;
*/
	}

	return 1;
}
#endif

AFB_error httpdStart(AFB_session * session)
{

	if (!my_default_init(session)) {
		printf("Error: initialisation of httpd failed");
		return AFB_FATAL;
	}

#if defined(USE_MAGIC_MIME_TYPE)
	/*TBD open libmagic cache [fail to pass EFENCE check (allocating 0 bytes)] */
	init_lib_magic (session);
#endif

	if (verbose) {
		printf("AFB:notice Waiting port=%d rootdir=%s\n", session->config->httpdPort, session->config->rootdir);
		printf("AFB:notice Browser URL= http:/*localhost:%d\n", session->config->httpdPort);
	}

	session->httpd = MHD_start_daemon(
		MHD_USE_EPOLL_LINUX_ONLY | MHD_USE_TCP_FASTOPEN | MHD_USE_DEBUG | MHD_USE_SUSPEND_RESUME,
		(uint16_t) session->config->httpdPort,	/* port */
		new_client_handler, NULL,	/* Tcp Accept call back + extra attribute */
		access_handler, session,	/* Http Request Call back + extra attribute */
		MHD_OPTION_NOTIFY_COMPLETED, end_handler, session,
		MHD_OPTION_CONNECTION_TIMEOUT, (unsigned int)15,	/* 15 seconds */
		MHD_OPTION_END);	/* options-end */

	if (session->httpd == NULL) {
		printf("Error: httpStart invalid httpd port: %d", session->config->httpdPort);
		return AFB_FATAL;
	}
	return AFB_SUCCESS;
}

/* infinite loop */
AFB_error httpdLoop(AFB_session * session)
{
	int count = 0;
	const union MHD_DaemonInfo *info;
	struct pollfd pfd;

	info = MHD_get_daemon_info(session->httpd, MHD_DAEMON_INFO_EPOLL_FD_LINUX_ONLY);
	if (info == NULL) {
		printf("Error: httpLoop no pollfd");
		goto error;
	}
	pfd.fd = info->listen_fd;
	pfd.events = POLLIN;

	if (verbose)
		fprintf(stderr, "AFB:notice entering httpd waiting loop\n");
	while (TRUE) {
		if (verbose)
			fprintf(stderr, "AFB:notice httpd alive [%d]\n", count++);
		poll(&pfd, 1, 15000);	/* 15 seconds (as above timeout when starting) */
		MHD_run(session->httpd);
	}

 error:
	/* should never return from here */
	return AFB_FATAL;
}

int httpdStatus(AFB_session * session)
{
	return MHD_run(session->httpd);
}

void httpdStop(AFB_session * session)
{
	MHD_stop_daemon(session->httpd);
}