/******************************************************************************
 *
 *                Copyright (c) 2017-2019 by Löwenware Ltd
 *             Please, refer LICENSE file for legal information
 *
 ******************************************************************************/

/**
 * @file mail.c
 * @author Ilja Kartašov <ik@lowenware.com>
 * @brief Mail sending component source file
 *
 * @see https://lowenware.com/aisl/
 */

#include <stdlib.h>
#include <string.h>
#include <cStuff/string.h>
#include <curl/curl.h>
#include "mail.h"


struct payload {
	char    now[40];
	char   *to;
	char   *from;
	char   *subject;
	char   *msg_id;
	char   *smtp_user;
	char   *smtp_pass;
	char   *smtp_url;
	char   *data;
	size_t  offset;
	size_t  total;
};


static size_t
payload_feed(void *ptr, size_t size, size_t nmemb, void *userp)
{
	struct payload *payload = (struct payload *)userp;
	size_t left;

	left = payload->total - payload->offset;

	if (left && (size = size*nmemb)) {
		if (size > left)
			size = left;

		memcpy(ptr, &payload->data[payload->offset], size);
		payload->offset += size;

		return size;
	}

	return 0;
}


static void
payload__get_now(char *now, size_t size)
{
	time_t time_now = time(NULL);
	struct tm tm;

	gmtime_r(&time_now, &tm);
	strftime(now, size, "%a, %d %b %Y %H:%M:%S GMT", &tm);
}


static char *
payload__get_id(uuid_t uuid, const char *server)
{
	size_t sz = strlen(server);
	char *result = malloc( sz + 3 + 36 + 1 );

	if (result) {
		char * p =result;
		*(p++) = '<';
		uuid_unparse(uuid, p);
		p += 36;
		*(p++) = '@';
		strncpy(p, server, sz);
		p += sz;
		*(p++) = '>';
		*p = 0;
	}

	return result;
}


static void
payload_free(struct payload *payload)
{
	if (payload->data)
		free(payload->data);

	if (payload->to)
		free(payload->to);

	if (payload->from)
		free(payload->from);

	if (payload->subject)
		free(payload->subject);

	if (payload->msg_id)
		free(payload->msg_id);

	if (payload->smtp_user)
		free(payload->smtp_user);

	if (payload->smtp_pass)
		free(payload->smtp_pass);

	if (payload->smtp_url)
		free(payload->smtp_url);

	free(payload);
}


static struct payload *
payload_new(aislx_mail_t mail, const char *server)
{
	size_t total;
	struct payload *payload;

	if (!(payload = calloc(1, sizeof(struct payload))))
		goto except;

	payload__get_now(payload->now, sizeof(payload->now));

	if (cstuff_strcpy(&payload->to, mail->to) == -1)
		goto e_cleanup;

	if (cstuff_strcpy(&payload->from, mail->from) == -1)
		goto e_cleanup;

	if ( !(payload->msg_id = payload__get_id(mail->msg_id, server)) )
		goto e_cleanup;

	total = cstuff_sprintf( &payload->data, AISLX_MAIL_FORMAT
	  , payload->now
	  , payload->to
	  , payload->from
	  , mail->reply_to
	  , payload->msg_id
	  , mail->subject
	  , mail->msg );

	if (!(total > 0))
		goto e_cleanup;

	payload->total = total;

	return payload;

e_cleanup:
	payload_free(payload);

except:
	return payload;
}


static void *
aislx_mail_execute(void *p_ctx)
{
	struct payload * payload = (struct payload *)p_ctx;
	aisl_status_t status = AISL_MALLOC_ERROR;

	CURL *curl;
	struct curl_slist *rcpts;

	if ((curl = curl_easy_init()) != NULL) {
		curl_easy_setopt(curl, CURLOPT_USERNAME, payload->smtp_user);
		curl_easy_setopt(curl, CURLOPT_PASSWORD, payload->smtp_pass);
		curl_easy_setopt(curl, CURLOPT_URL,      payload->smtp_url);
		curl_easy_setopt(curl, CURLOPT_USE_SSL,  (long) CURLUSESSL_ALL);
		curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
		curl_easy_setopt(curl, CURLOPT_READFUNCTION, payload_feed);
		curl_easy_setopt(curl, CURLOPT_READDATA, payload);
		curl_easy_setopt(curl, CURLOPT_UPLOAD, 1L);
		curl_easy_setopt(curl, CURLOPT_VERBOSE, 1L);

		curl_easy_setopt(curl, CURLOPT_MAIL_FROM, payload->from);

		if ((rcpts = curl_slist_append(NULL, payload->to)) != NULL) {
			CURLcode res;

			if ((res = curl_easy_perform(curl)) != CURLE_OK) {
				fprintf(stderr, "curl_easy_perform() failed: %s\n"
					, curl_easy_strerror(res));
				status = AISL_INPUT_ERROR;
			} else {
				status = AISL_SUCCESS;
			}
			curl_slist_free_all(rcpts);
		}
		curl_easy_cleanup(curl);
	}

	return (void*)status;
}


aisl_status_t
aislx_mail_send( aislx_mail_t    mail,
                 const char     *smtp_server,
                 const char     *smtp_user,
                 const char     *smtp_pass,
                 int             flags )
{
	int rc;
	struct payload *payload;

	if (!(payload = payload_new(mail, smtp_server)))
		return AISL_MALLOC_ERROR;

	rc = pthread_create(&mail->thread, NULL, aislx_mail_execute, (void*)payload);
	if (rc) {
		payload_free(payload);
		return AISL_SYSCALL_ERROR;
	}
	return AISL_SUCCESS;
}


aisl_status_t
aislx_mail_get_status(aislx_mail_t mail)
{
	int rc;
	void * retval;

	rc = pthread_tryjoin_np(mail->thread, &retval);

	if (rc == 0) {
		rc = (aisl_status_t)retval;
		return rc;
	} else {
		return AISL_IDLE;
	}
}