/*
 * Copyright (C) 2016 Andy Spencer <andy753421@gmail.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdio.h>

#include <curl/curl.h>
#include <expat.h>

#include "util.h"
#include "conf.h"
#include "date.h"
#include "cal.h"

/* Local Types */
typedef struct ews_t {
	cal_t         cal;
	struct ews_t *next;

	// Config
	char         *username;
	char         *password;
	char         *location;
	char         *domain;

	// Parsing
	CURL         *curl;
	XML_Parser    expat;
	buf_t         buf;

	// Debugging
	int           debug;
	int           indent;
} ews_t;

/* Static data */
static ews_t *calendars;
static CURLM *curlm;

/* SOAP Requests */
static char *req_calendar =
	"<?xml version=\"1.0\" encoding=\"utf-8\" ?>\n"
	"<soap:Envelope xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\"\n"
	"               xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\"\n"
	"               xmlns:soap=\"http://schemas.xmlsoap.org/soap/envelope/\"\n"
	"               xmlns:t=\"http://schemas.microsoft.com/exchange/services/2006/types\"\n"
	"               xmlns:m=\"http://schemas.microsoft.com/exchange/services/2006/messages\">\n"
	"    <soap:Body>\n"
	"        <m:FindItem Traversal=\"Shallow\">\n"
	"            <m:ItemShape>\n"
	"                <t:BaseShape>IdOnly</t:BaseShape>\n"
	"                <t:AdditionalProperties>\n"
	"                    <t:FieldURI FieldURI=\"calendar:CalendarItemType\" />\n"
	"                    <t:FieldURI FieldURI=\"calendar:Start\" />\n"
	"                    <t:FieldURI FieldURI=\"calendar:End\" />\n"
	"                    <t:FieldURI FieldURI=\"item:ItemClass\" />\n"
	"                    <t:FieldURI FieldURI=\"item:Subject\" />\n"
	"                </t:AdditionalProperties>\n"
	"            </m:ItemShape>\n"
	"            <m:CalendarView StartDate=\"2016-01-01T00:00:00-00:00\"\n"
	"                            EndDate=\"2018-01-01T00:00:00-00:00\"\n"
	"                            MaxEntriesReturned=\"1000\" />\n"
	"            <m:ParentFolderIds>\n"
	"                <t:DistinguishedFolderId Id=\"calendar\" />\n"
	"            </m:ParentFolderIds>\n"
	"        </m:FindItem>\n"
	"    </soap:Body>\n"
	"</soap:Envelope>\n"
;

/* Local functions */
static void on_start(void *_cal, const char *tag, const char **attrs)
{
	ews_t *cal = _cal;

	/* Debug print */
	if (cal->debug) {
		printf("%*s%s\n",
			cal->indent*4, "", tag);
		for (int i = 0; attrs[i]; i += 2) {
			printf("%*s %s=\"%s\"\n",
				cal->indent*4+6, "--",
				attrs[i+0], attrs[i+1]);
			attrs+=2;
		}
		cal->indent++;
	}
}

static void on_end(void *_cal, const char *tag)
{
	ews_t *cal = _cal;

	/* Debug print */
	if (cal->debug) {
		if (cal->buf.len)
			printf("%*s \"%s\"\n",
				cal->indent*4+2, "--",
				(char*)cal->buf.data);
		cal->indent--;
	}

	/* Parse items */
	cal->buf.len = 0;
}

static void on_data(void *_cal, const char *data, int len)
{
	ews_t *cal = _cal;
	if (cal->debug)
		append(&cal->buf, data, len);
}

static size_t on_write(void *buf, size_t size, size_t n, ews_t *cal)
{
	int len = size * n;
	XML_Parse(cal->expat, buf, len, 0);
	return len;
}

static void sync_ews(ews_t *cal)
{
	CURLcode err;
	long status;
	struct curl_slist *hdr = NULL;

	/* Debug output */
	debug("Loading EWS:");
	debug("  type     = %s", cal->cal.type);
	debug("  name     = %s", cal->cal.name);
	debug("  desc     = %s", cal->cal.desc);
	debug("  username = %s", cal->username);
	debug("  password = %s", cal->password);
	debug("  location = %s", cal->location);
	debug("  domain   = %s", cal->domain);

	/* Setup Expat */
	if (!(cal->expat = XML_ParserCreate(NULL)))
		error("XML Parser Create");
	XML_SetUserData(cal->expat, cal);
	XML_SetStartElementHandler(cal->expat, on_start);
	XML_SetEndElementHandler(cal->expat, on_end);
	XML_SetCharacterDataHandler(cal->expat, on_data);

	/* Setup HTTP request */
	if (!(cal->curl = curl_easy_init()))
		error("Curl easy init failed");
	if (curl_easy_setopt(cal->curl, CURLOPT_URL, cal->location))
		error("Curl easy setopt failed");
	if (curl_easy_setopt(cal->curl, CURLOPT_WRITEFUNCTION, on_write))
		error("Curl easy set write function failed");
	if (curl_easy_setopt(cal->curl, CURLOPT_WRITEDATA, cal))
		error("Curl easy set write data failed");

	/* Skip SSL checks */
	if (curl_easy_setopt(cal->curl, CURLOPT_SSL_VERIFYPEER, 0L))
		error("Curl easy set no verify peer failed");
	if (curl_easy_setopt(cal->curl, CURLOPT_SSL_VERIFYHOST, 0L))
		error("Curl easy set no verify hosts failed");

	/* Set login info */
	if (curl_easy_setopt(cal->curl, CURLOPT_HTTPAUTH, CURLAUTH_ANY))
		error("Curl easy set http auth failed");
	if (curl_easy_setopt(cal->curl, CURLOPT_USERNAME, cal->username))
		error("Curl easy set username failed");
	if (curl_easy_setopt(cal->curl, CURLOPT_PASSWORD, cal->password))
		error("Curl easy set password failed");

	/* Setup SOAP request */
	hdr = curl_slist_append(hdr, "Accept: text/xml");
	hdr = curl_slist_append(hdr, "Content-Type: text/xml");
	if (curl_easy_setopt(cal->curl, CURLOPT_HTTPHEADER, hdr))
		error("Curl easy set http header failed");
	if (curl_easy_setopt(cal->curl, CURLOPT_POST, 1L))
		error("Curl easy set post failed");
	if (curl_easy_setopt(cal->curl, CURLOPT_POSTFIELDS, req_calendar))
		error("Curl easy set post failed");

	/* Curl Easy */
	if ((err = curl_easy_perform(cal->curl)))
		error("Curl easy perform failed: %s", curl_easy_strerror(err));
	if ((err = curl_easy_getinfo(cal->curl, CURLINFO_RESPONSE_CODE, &status)))
		error("Curl easy get info failed: %s", curl_easy_strerror(err));

	/* Output response */
	if (cal->debug)
		printf("EWS -- HTTP Status %ld\n", status);
	if (cal->debug && !cal->buf.data)
		printf("EWS -- No Response Data\n");

	/* Cleanup */
	curl_easy_cleanup(cal->curl);
	XML_ParserFree(cal->expat);
}

/* Config parser */
void ews_config(const char *group, const char *name, const char *key, const char *value)
{
	ews_t *cal = NULL, *last = NULL;

	/* Make sure it's valid */
	if (!match(group, "ews") || !name)
		return;

	/* Find existing calendar */
	for (cal = calendars; cal; last = cal, cal = cal->next)
		if (match(cal->cal.name, name))
			break;

	/* Create new calendar */
	if (!cal) {
		cal = new0(ews_t);
		cal->cal.type = "ews";
		cal->cal.name = get_name(name);
		if (last)
			last->next = cal;
		else
			calendars = cal;
	}

	/* Set calendar values */
	if (match(key, "location"))
		cal->location = get_string(value);
	else if (match(key, "username"))
		cal->username = get_string(value);
	else if (match(key, "password"))
		cal->password = get_string(value);
	else if (match(key, "domain"))
		cal->domain = get_string(value);
}

/* Cal functions */
cal_t *ews_cals(void)
{
	for (ews_t *cal = calendars; cal; cal = cal->next) {
		sync_ews(cal);
		cal->cal.next = &cal->next->cal;
	}

	return &calendars->cal;
}

/* Event functions */
event_t *ews_events(date_t start, date_t end)
{
	return NULL;
}

/* Todo functions */
todo_t *ews_todos(date_t start, date_t end)
{
	return NULL;
}

/* Test functions */
void ews_test(char *url, char *user, char *pass)
{
	ews_t cal = {
		.location = url,
		.username = user && user[0] ? user : NULL,
		.password = pass && pass[0] ? pass : NULL,
		.debug    = 1,
	};

	/* Setup CURL */
	printf("EWS -- test start\n");
	if (curl_global_init(CURL_GLOBAL_DEFAULT))
		error("Curl global init failed");
	if (!(curlm = curl_multi_init()))
		error("Curl multi init failed");

	/* Sync the calendar */
	sync_ews(&cal);

	/* Cleanup */
	curl_multi_cleanup(curlm);
	curl_global_cleanup();
	printf("EWS -- test end\n");
}