path: root/src/api.c

#pragma once
#include <sys/types.h>
#include <stdlib.h>
#include <stdio.h>
#include <curl/curl.h>
#include <unistd.h>
#include <i18n.h>
#include <string.h>
#include <lib.c>
#include <cjson/cJSON.h>
#include <time.h>
#include <stdarg.h>
#include <printf.h>
#include <pthread.h>
#include <stdatomic.h>
#include <math.h>
#include <signal.h>
#define DC_API_PREFIX "https://discord.com/api/v8/" /* this can be a format string, DO NOT use format characters inside */
#define DC_LOGIN_FORMAT "{\"login\":\"%s\",\"password\":\"%s\",\"undelete\":false,\"captcha_key\":null,\"login_source\":null,\"gift_code_sku_id\":null}"
#define DC_USER_AGENT "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/74.0.3729.131 Safari/537.36"
#define DC_ERROR(c, m, ...) (dc_push_error(c, __func__, __FILE__, __LINE__, 0##__VA_OPT__(1), m __VA_OPT__(,) __VA_ARGS__))
/* #define DC_ERROR(c, m, ...) (fprintf(stderr, "%s()@" __FILE__ ":%d: " m "\n", __func__, __LINE__ __VA_OPT__(,) __VA_ARGS__)) */
#define DC_CLIENT_ERROR(c, m, ...) DC_ERROR(c, m __VA_OPT__(,) __VA_ARGS__) /* yeah, that m is not a typo */
#define DC_CAPI(c, body, endpoint, ...) dc_api(c, body, 0##__VA_OPT__(1), endpoint __VA_OPT__(,) __VA_ARGS__)
#define cJSON_GetObjectItem2(root, name1, name2) (cJSON_GetObjectItem(root, name1) ? cJSON_GetObjectItem(cJSON_GetObjectItem(root, name1), name2) : NULL)
#define DC_TIMESTAMP_FORMAT "%Y-%m-%dT%H:%M:%S.XXXXXX%z"
#define DC_SHORTTIMESTAMP_FORMAT "%Y-%m-%dT%T%z"
#define DC_CWLE(c, name) (pthread_rwlock_wrlock(name) ? (DC_CLIENT_ERROR(c, DC_I18N_LOCKING " " #name " " DC_I18N_FAILED) || 1) : 0)
#define DC_CRLE(c, name) (pthread_rwlock_rdlock(name) ? (DC_CLIENT_ERROR(c, DC_I18N_LOCKING " " #name " " DC_I18N_FAILED) || 1) : 0)
#define DC_CUE(c, name) (pthread_rwlock_unlock(name) ?(DC_CLIENT_ERROR(c, DC_I18N_UNLOCKING " " #name " " DC_I18N_FAILED) || 1) : 0)
/*
	struct members comment information:
	- noui: the ui thread must not use the member (for example curl pointers are noui)
	- noapi: the api thread must not use the member
	- nofree: the (string) pointer is of a static string, do not attempt to free it (for example function, file, message in dc_error)
	- yesfree: the (string) pointer is of a dynamically-allocated string, free it before losing pointer to the struct (most strings)
	- nouiw: ui must not write
	- noapiw: api must not write
	- nolock: no lock is required if only reading is done after a single write to the memory area or only one thread accesses it
	guidelines:
	- when threading, you must use mutexes to prevent accessing structs (and their pointers because of realloc!) (optionaly with timeouts that are optionaly reported with DC_CLIENT_ERROR)
	- error reporting function shall not report an error to itself when mutex lock times out for obvious reasons
	- _sizeofs shall represent the size of arrays in atomic types
	- keep arrays as arrays of pointers, not direct structs, as that allows pointing to individual elements without them changing pointer addresses
	- threading and races 101: when popping arrays, always lock in a non-shared way, same obviously applies for sorting, writing, appending (because of reallocs of pointer arrays)
	mutexes:
	- mutexes for child members are kept in the struct with the object that is being modified. if realloc is used on strings or those child objects (pointers change), the whole struct must be locked.
	- when reading arrays of pointers, you shared lock it
	- when writing, lock the memory in a non shared way, take note of the pointer in case of realloc
	struct pointed to from multiple sections (a great example is a channel)
	- when a channel is created, DO NOT destroy it - never free channels if you don't free messages, never free guilds if you don't free channels. that's because channels in guilds are backpointed to parent guilds and messages are backpointed to channels, realloc would lead to a segfault.
	- use posixes pthread_rwlock_init(3POSIX) mutexes to allow reading to arrays and other types
	- do not have the illusion that you can append to an array of pointers without non-shared locking, because you realloc that array of pointers, appending must also be non-shared locked
	- _free functions shall never fail - do not use timed locks
	- i changed arrays from type arrays to type pointer arrays, so code that allocates must be reimplemented, also struct free functions and -> instead of . in array elements
*/
struct dc_error {
	size_t line;
	const char * function; /* nofree */
	char * file; /* nofree */
	char * message; /* yesfree */
	time_t time;
	short unsigned int reported /* 0: error was not yet shown to the user, 1: error was already shown to the user */;
};
void dc_error_free(struct dc_error * e) { /* noui, noapi, nolock - only called by dc_client_free */
	free(e->message); e->message = NULL; /* other strings are static */
	e->line = 0;
	e->function = NULL;
	e->file = NULL;
	e->reported = 0;
	free(e);
}
struct dc_message {
	char * username; /* yesfree */
	int discriminator;
	char * content; /* yesfree */
	char * attachment; /* yesfree - url to the attachment should it exist */
	time_t time;
	_Atomic(struct dc_channel *) channel; /* nofree */
	unsigned short int tts;
	unsigned long long int id; /* nouiw */
	unsigned short int status; /* noapiw - 0 if it was not yet printed on the display, 1 if it was */
};
void dc_message_free (struct dc_message * m) { /* noui, noapi, nolock - only called by dc_channel_free */
	free(m->username); m->username = NULL;
	free(m->content); m->content = NULL;
	free(m->attachment); m->attachment = NULL;
	m->channel = NULL;
	m->tts = 0;
	m->discriminator = -1;
	m->id = 0;
	/* i'm not sure how to "unset" time_t ... */
	free(m);
}
int dc_message_compare (const void * a, const void * b) {
	struct dc_message * c = *(struct dc_message **) a;
	struct dc_message * d = *(struct dc_message **) b;
	/* strežnik v arrayu najprej pošlje sporočila iz sedanjosti, nato tista iz preteklosti, zato bo tudi sortiran array takšen */
	return c->time > d->time ? -1 : c->time < d->time ? 1 : 0;
}
struct dc_channel {
	char * name; /* yesfree, nouiw */
	char * topic; /* yesfree, nouiw */
	unsigned long long int id; /* nouiw */
	_Atomic(struct dc_guild *) guild; /* nofree, nouiw */
	struct dc_message ** messages; /* yesfree, nouiw */
	_Atomic(size_t) messages_sizeof; /* nouiw */
	int slowmode; /* nouiw - number of seconds to wait in case of slowmode, HANDLED BY THE USER INTERFACE!! */
	unsigned short int joined; /* noapiw, if joined (1) api will fetch messages and ui display them. api will still send messages even if this is not set */
	unsigned short int focused; /* noapi, if focused (1) ui will send messages to this channel */
};
void dc_channel_free (struct dc_channel * ch) { /* noui, noapi, nolock - only called by dc_guild_free */
	free(ch->name); ch->name = NULL;
	free(ch->topic); ch->topic = NULL;
	ch->guild = NULL;
	ch->id = 0;
	for (int i = 0; i < ch->messages_sizeof; i++)
		dc_message_free(ch->messages[i]);
	free(ch->messages);
	ch->messages_sizeof = 0;
	free(ch);
}
struct dc_guild {
	char * name; /* nouiw, yesfree */
	unsigned long long id; /* nouiw */
	_Atomic(size_t) channels_sizeof; /* nouiw */
	struct dc_channel ** channels; /* yesfree, nouiw */
	_Atomic(struct dc_client *) client; /* nofree - obviously */
	char * altmsgurl; /* yesfree - alternative messages url - used for virtual guild for DMs */
};
void dc_guild_free (struct dc_guild * g) { /* noui, noapi, nolock - only called by dc_client_free */
	free(g->name); g->name = NULL;
	g->id = 0;
	for (int i = 0; i < g->channels_sizeof; i++)
		dc_channel_free(g->channels[i]);
	free(g->channels);
	g->channels_sizeof = 0;
	free(g->altmsgurl);
	free(g);
}
struct dc_client {
	CURL * curl; /* noui, nolock */
	struct curl_slist * curl_headers; /* noui, nolock */
	char * authorization; /* nouiw */
	pthread_rwlock_t * authorization_lock;
	char * email; /* yesfree, noapiw, nolock */
	char * password; /* yesfree, noapiw, nolock */
	char * username; /* yesfree, nouiw */ 
	pthread_rwlock_t * username_lock;
	_Atomic(int) discriminator; /* nouiw - -1: the user is not logged in, -2: user login failed and will not be retried, < 0: the user is not logged in */
	struct dc_guild ** guilds; /* yesfree, nouiw */
	_Atomic(size_t) guilds_sizeof; /* nouiw */
	pthread_rwlock_t * guilds_lock;
	struct dc_error ** errors; /* yesfree */
	_Atomic(size_t) errors_sizeof;
	pthread_rwlock_t * errors_lock;
	struct dc_message ** sent_messages; /* yesfree - ui appends, api pops and moves to messages */
	_Atomic(size_t) sent_messages_sizeof;
	pthread_rwlock_t * sent_messages_lock;
	_Atomic(time_t) last_sent_message; /* for slowmode implementations */
	_Atomic(short unsigned int) newmessages; /* > 0 if api got new messages. ui resets to 0 - nolock - ui should still check without this flag for new messages - racy */
};
struct dc_client * dc_client_init () { /* gives you a prepared dc_client */
	struct dc_client * c = calloc(1, sizeof(struct dc_client));
	c->discriminator = -1;
	c->guilds_sizeof = 1;
	c->guilds = calloc(1, sizeof(struct dc_guild *));
	c->guilds[0] = calloc(1, sizeof(struct dc_guild));
	c->guilds[0]->name = malloc(strlen(DC_I18N_DMS)+1);
	strcpy(c->guilds[0]->name, DC_I18N_DMS);
	c->guilds[0]->altmsgurl = malloc(strlen(DC_API_PREFIX "users/@me/channels")+1);
	strcpy(c->guilds[0]->altmsgurl, DC_API_PREFIX "users/@me/channels");
	c->guilds[0]->client = c;
#define DC_CILI(name) /* Client Init Lock Init */ do { name##_lock = malloc(sizeof(pthread_rwlock_t)); pthread_rwlock_init(name##_lock, NULL); } while(0)
	DC_CILI(c->authorization);
	DC_CILI(c->username);
	DC_CILI(c->guilds);
	DC_CILI(c->errors);
	DC_CILI(c->sent_messages);
	return c;
}
void dc_client_free (struct dc_client * c) { /* noui, noapi, nolock - only called by main on exit */
	curl_easy_cleanup(c->curl);
	c->curl = NULL;
	curl_slist_free_all(c->curl_headers);
	c->curl_headers = NULL;
	free(c->authorization); c->authorization = NULL;
	free(c->email); c->email = NULL;
	free(c->password); c->password = NULL;
	free(c->username); c->username = NULL;
	c->discriminator = -1;
	for (int i = 0; i < c->guilds_sizeof; i++)
		dc_guild_free(c->guilds[i]);
	free(c->guilds);
	c->guilds_sizeof = 0;
	for (int i = 0; i < c->errors_sizeof; i++)
		dc_error_free(c->errors[i]);
	free(c->errors);
	c->errors_sizeof = 0;
	for (int i = 0; i < c->sent_messages_sizeof; c++)
		dc_message_free(c->sent_messages[i]);
	free(c->sent_messages);
	c->sent_messages_sizeof = 0;
#define DC_CFLD(name) do { pthread_rwlock_destroy(name##_lock); free(name##_lock); } while(0)
	DC_CFLD(c->authorization);
	DC_CFLD(c->username);
	DC_CFLD(c->guilds);
	DC_CFLD(c->errors);
	DC_CFLD(c->sent_messages);
	free(c);
}
int dc_push_error (struct dc_client * c, const char * caller, char * f, size_t l, unsigned short int isfmt, char * m, ...) {
#define DC_PEE /* dc scalnia oziroma push error error */ c->errors[c->errors_sizeof-1]
	if (!c)
		return -2;
	pthread_rwlock_t * lock = c->errors_lock;
	if (!lock)
		return -3;
	if (pthread_rwlock_wrlock(lock))
		return -1; /* does not report an error as that may make things even worse. I could try writing to stderr here but meh */
	c->errors = realloc(c->errors, sizeof(struct dc_error *)*++c->errors_sizeof); /* note: format arguments are evaluated twice */
	DC_PEE = malloc(sizeof(struct dc_error));
	size_t strlenm = strlen(m);
	size_t va_count = parse_printf_format(m, 0, NULL);
	if (isfmt && va_count > 0) {
		va_list ap, ap2;
		va_start(ap, m);
		va_copy(ap2, ap);
		strlenm = vsnprintf(NULL, 0, m, ap);
		DC_PEE->message = malloc(sizeof(char)*strlenm+1);
		vsnprintf(DC_PEE->message, strlenm+1, m, ap2);
		va_end(ap);
		va_end(ap2);
	} else {
		DC_PEE->message = malloc(sizeof(char)*strlenm+1);
		strcpy(DC_PEE->message, m);
	}
	DC_PEE->file = f;
	DC_PEE->line = l;
	DC_PEE->function = caller /* Caller */;
	DC_PEE->time = time(NULL);
	DC_PEE->reported = 0;
	if (lock && pthread_rwlock_unlock(lock))
		return -2;
	return 1;
}
cJSON * dc_api (struct dc_client * c, char * body, int isfmt, char * endpoint, ...) { /* note: format arguments are evaluated twice */
	if (!c)
		return NULL;
	if (!c->curl) {
		DC_CLIENT_ERROR(c, "!c->curl");
	}
	if (!c->curl) {
		DC_CLIENT_ERROR(c, "!c->curl");
		return NULL;
	}
	if (!endpoint) {
		DC_CLIENT_ERROR(c, "!endpoint");
		return NULL;
	}
	cJSON * json = NULL;
	struct writefunc_string * s = malloc(sizeof(struct writefunc_string));
	struct writefunc_string * h = malloc(sizeof(struct writefunc_string));
	size_t va_count = parse_printf_format(endpoint, 0, NULL);
	char * endpoint_formatted = NULL;
	int retried = 0;
	long response_code = 0;
	retry:
	init_writefunc_string(s);
	init_writefunc_string(h);
	if (isfmt && va_count > 0 && endpoint_formatted == NULL) {
		va_list ap, ap2;
		va_start(ap, endpoint);
		va_copy(ap2, ap);
		size_t strlenm = vsnprintf(NULL, 0, endpoint, ap);
		endpoint_formatted = malloc(sizeof(char)*strlenm+1);
		vsnprintf(endpoint_formatted, strlenm+1, endpoint, ap2); /* sn instead of s because double evaulation may produce */
		va_end(ap); /* larger output the next time and lead to overflow */
		va_end(ap2);
	}
	curl_easy_setopt(c->curl, CURLOPT_URL, endpoint_formatted ? endpoint_formatted : endpoint);
	curl_easy_setopt(c->curl, CURLOPT_POSTFIELDS, body); /* yes, even null is okay, it's actually a must as it makes sure curl clears old pointers and does not read freed memory. see https://github.com/curl/curl/issues/3214#issuecomment-435335974 */
	if (!body)
		curl_easy_setopt(c->curl, CURLOPT_HTTPGET, 1L); /* this must be done after postfields */
	curl_easy_setopt(c->curl, CURLOPT_WRITEDATA, s);
	curl_easy_setopt(c->curl, CURLOPT_NOSIGNAL, 1L);
	curl_easy_setopt(c->curl, CURLOPT_HEADERDATA, h);
	curl_easy_setopt(c->curl, CURLOPT_FOLLOWLOCATION, 1L);
	curl_easy_setopt(c->curl, CURLOPT_HTTPHEADER, c->curl_headers);
	curl_easy_setopt(c->curl, CURLOPT_TIMEOUT, 20L); /* 20 second timeout */
	curl_easy_setopt(c->curl, CURLOPT_HEADERFUNCTION, writefunc);
	curl_easy_setopt(c->curl, CURLOPT_WRITEFUNCTION, writefunc);
	if (curl_easy_perform(c->curl) != CURLE_OK) {
		DC_CLIENT_ERROR(c, "curl_easy_perform(curl) != CURLE_OK");
		goto rc;
	} else {
		curl_easy_getinfo(c->curl, CURLINFO_RESPONSE_CODE, &response_code);
	}
#ifdef DC_NETREQ
	fprintf(netreq, "%s\n%s\n%s\n%s====================================\n", endpoint_formatted ? endpoint_formatted : endpoint, body ? body : "GET", h->ptr, s->ptr);
	fflush(netreq);
#endif
	json = cJSON_Parse(s->ptr);
	if (!json) {
		const char * error_ptr = cJSON_GetErrorPtr();
		if (error_ptr) {
			DC_CLIENT_ERROR(c, "cJSON_Parse " DC_I18N_FAILED ": " DC_I18N_JSON_ERROR_BEFORE ": %.21s s->ptr = %s", error_ptr, s->ptr);
		} else {
			DC_CLIENT_ERROR(c, "cJSON_Parse " DC_I18N_FAILED ". s->ptr = %s", s->ptr ? s->ptr : "NULL");
		}
		goto rc;
	}
	/* note that the server does not send x-ratelimit headers for normal users and cJSON has problems with parsing floats, so caveman approach is needed */
	char * cp = cJSON_GetStringValue(cJSON_GetObjectItem(json, "retry_after"));
	if (cp && (cp = strstr(cp, "\"retry_after\": "))) { /* note: make sure to always check if retry_after is in the root of the object, otherwise you can get dosed if a user somehow inserts "retry_after": into a message or something. we could check error code though, but naaaah */
		if (!(cp = strchr(cp, ' ')))
			goto rc;
		int retry_after = atoi(++cp)+1;
		DC_CLIENT_ERROR(c, DC_I18N_HITRL " %lfs. endpoint = %s", retry_after, endpoint_formatted ? endpoint_formatted : endpoint);
		sleep(retry_after); /* TODO: prevent hanging entire thread just for this */
		free(s->ptr); s->ptr = NULL;
		free(h->ptr); h->ptr = NULL;
		free(s); s = NULL;
		free(h); h = NULL;
		cJSON_Delete(json);
		json = NULL;
		if (retried++)
			return NULL;
		goto retry;
	}
	rc:
	curl_easy_setopt(c->curl, CURLOPT_HEADERFUNCTION, NULL); /* for usages that don't use headerfunction */
	free(endpoint_formatted);
	free(s->ptr); s->ptr = NULL;
	free(h->ptr); h->ptr = NULL;
	free(s); s = NULL;
	free(h); h = NULL;
	return json;
}
int dc_login (struct dc_client * c) { /* noui */
	int rs = 1;
	char * data = NULL;
	cJSON * json = NULL;
	if (!c)
		return -1;
	if (!c->email || !c->password) {
		DC_CLIENT_ERROR(c, DC_I18N_MISSING_EP);
		return -2;
	}
	if (!c->curl)
		c->curl = curl_easy_init();
	if (!c->curl) {
		DC_CLIENT_ERROR(c, "curl_easy_init() " DC_I18N_FAILED);
		return -3;
	}
	data = malloc(snprintf(NULL, 0, DC_LOGIN_FORMAT, c->email, c->password)+1);
	sprintf(data, DC_LOGIN_FORMAT, c->email, c->password);
	/* curl_slist_free_all(c->curl_headers); */
	c->curl_headers = curl_slist_append(c->curl_headers, "Content-Type: application/json");
	c->curl_headers = curl_slist_append(c->curl_headers, "User-Agent: " DC_USER_AGENT);
	json = DC_CAPI(c, data, DC_API_PREFIX "auth/login");
	if (!json) {
		DC_CLIENT_ERROR(c, "!DC_CAPI auth/login, data = %s", data);
		rs = -4;
		goto rc;
	}
	cJSON * token = cJSON_GetObjectItem(json, "token");
	if (!cJSON_IsString(token)) {
		DC_CLIENT_ERROR(c, "!cJSON_IsString(token)");
		rs = -6;
		goto rc;
	}
	if (DC_CWLE(c, c->authorization_lock)) {rs = -7; goto rc;}
	c->authorization = realloc(c->authorization, strlen(token->valuestring)+1);
	strcpy(c->authorization, token->valuestring);
	data = realloc(data, strlen(c->authorization)+strlen("Authorization: ")+1+1/* last one because valgrind was complaining */);
																					strcpy(data, "Authorization: ");
	strcat(data, c->authorization);
	if (DC_CUE(c, c->authorization_lock)) {rs = -8; goto rc;}
	c->curl_headers = curl_slist_append(c->curl_headers, data);
	cJSON_Delete(json);
	json = DC_CAPI(c, NULL, DC_API_PREFIX "users/@me");
	if (!json) {
		DC_CLIENT_ERROR(c, "!DC_CAPI users/@me");
		rs = -7;
		goto rc;
	}
	token = cJSON_GetObjectItem(json, "username");
	cJSON * token2 = cJSON_GetObjectItem(json, "discriminator");
	if (!cJSON_IsString(token) || !cJSON_IsString(token2)) {
		DC_CLIENT_ERROR(c, "!cJSON_IsString(token) || !cJSON_IsString(token2)");
		rs = -11;
		goto rc;
	}
	if (DC_CWLE(c, c->username_lock)) {rs = -11; goto rc;}
	c->username = realloc(c->username, strlen(token->valuestring)+1);
	strcpy(c->username, token->valuestring);
	if (DC_CUE(c, c->username_lock)) {rs = -12; goto rc;}
	c->discriminator = strtol(token2->valuestring, NULL, 10);
	rc:
	free(data); data = NULL;
	cJSON_Delete(json);
	return rs;
}
int dc_fetch_guilds (struct dc_client * c) {
	if (!c)
		return -5;
	int rs = 1;
	char * value = NULL;
	char * value2 = NULL;
	cJSON * json = NULL;
	if (c->discriminator < 0) {
		if ((rs = dc_login(c)) < 0) {
			DC_CLIENT_ERROR(c, "dc_login(c) " DC_I18N_FAILED " (%d)", rs);
			return -1;
		} else rs = 1;
	}
	json = DC_CAPI(c, NULL, DC_API_PREFIX "users/@me/guilds");
	if (!json) {
		DC_CLIENT_ERROR(c, "DC_CAPI users/@me/guilds " DC_I18N_FAILED);
		rs = -3;
		goto rc;
	}
	if (!cJSON_IsArray(json)) {
		DC_CLIENT_ERROR(c, "!cJSON_IsArray(json)");
		rs = -4;
		goto rc;
	}
	if(DC_CWLE(c, c->guilds_lock)) {rs = -5; goto rc;}
	cJSON * guild = NULL;
	cJSON_ArrayForEach(guild, json) {
		int skip = 0;
		value = cJSON_GetStringValue(cJSON_GetObjectItem(guild, "name"));
		value2 = cJSON_GetStringValue(cJSON_GetObjectItem(guild, "id"));
		if (!value || !value2) {
			char * jsonstr = cJSON_Print(json);
			DC_CLIENT_ERROR(c, "!cJSON_GetStringValue(cJSON_GetObjectItem(json, \"id\" || \"name\")) json = %s", jsonstr);
			free(jsonstr);
			continue;
		}
		unsigned long long int idull = strtoull(value2, NULL, 10);
		for (int i = 0; i < c->guilds_sizeof; i++)
			if (idull == c->guilds[i]->id) {
				skip = 1;
				break; /* remove duplicates */
			}
		if (skip) continue;
		c->guilds = realloc(c->guilds, sizeof(struct dc_guild *)*++c->guilds_sizeof);
		c->guilds[c->guilds_sizeof-1] = calloc(1, sizeof(struct dc_guild));
		c->guilds[c->guilds_sizeof-1]->name = malloc(strlen(value)+1);
		strcpy(c->guilds[c->guilds_sizeof-1]->name, value);
		c->guilds[c->guilds_sizeof-1]->id = idull;
		c->guilds[c->guilds_sizeof-1]->client = c;
	}
	if(DC_CUE(c, c->guilds_lock)) {rs = -6; goto rc;}
	rc:
	cJSON_Delete(json); json = NULL;
	return rs;
}
int dc_fetch_channels (struct dc_guild * g) {
	int rs = 1;
	if (!g)
		return -1;
	struct dc_client * c = g->client;
	if (!c)
		return -2;
	if (c->discriminator < 0) {
		if ((rs = dc_login(c)) < 0) {
			DC_CLIENT_ERROR(c, "dc_login(c) " DC_I18N_FAILED " (%d)", rs);
			return -3;
		} else rs = 1;
	}
	cJSON * json = NULL;
	if (g->altmsgurl)
		json = DC_CAPI(c, NULL, g->altmsgurl); /* used for private dm channels */
	else
		json = DC_CAPI(c, NULL, DC_API_PREFIX "guilds/%llu/channels", g->id); /* ids are only written by api thread, nolock */
	if (!json) {
		DC_CLIENT_ERROR(c, "DC_CAPI id = %llu, g->altmsgurl = %s" DC_I18N_FAILED, g->id, g->altmsgurl ? g->altmsgurl : "NULL" /* static string */);
		rs = -5;
		goto rc;
	}
	if (!cJSON_IsArray(json)) {
		char * jsonstr = cJSON_Print(json);
		DC_CLIENT_ERROR(c, "!cJSON_IsArray(json), g->id = %llu, g->altmsgurl = %s, json = %s", g->id, g->altmsgurl ? g->altmsgurl : "NULL", jsonstr);
		free(jsonstr);
		rs = -6;
		goto rc;
	}
	cJSON * channel = NULL;
	/* cJSON * perms = NULL; */ /* I'll rather not remove the channels with perms and let the user get banned for joining a channel without perms */
	/* cJSON * perm = NULL; */
	/* we lock all client guilds when doing stuff with channels */
	if (DC_CWLE(c, c->guilds_lock)) {rs = -7; goto rc;}
	cJSON_ArrayForEach(channel, json) {
		int skip = 0;
		/* if (cJSON_IsArray(perms = cJSON_GetObjectItem(channel, "permission_overwrites")));
		cJSON_ArrayForEach(perm, perms) {
			skip++;
		}
		if (skip) continue; */
		char * topic = cJSON_GetStringValue(cJSON_GetObjectItem(channel, "topic"));
		char * name = cJSON_GetStringValue(cJSON_GetObjectItem(channel, "name"));
		char * id = cJSON_GetStringValue(cJSON_GetObjectItem(channel, "id"));
		cJSON * type = cJSON_GetObjectItem(channel, "type");
		cJSON * jsonslowmode = cJSON_GetObjectItem(channel, "rate_limit_per_user");
		if (!cJSON_IsNumber(type) || !id) {
			char * krneki = cJSON_Print(channel);
			DC_CLIENT_ERROR(c, "!cJSON_IsNumber(type) || !id, channel = %s", krneki);
			free(krneki); krneki = NULL;
			continue;
		}
		if (type->valueint != 0 && type->valueint != 3 && type->valueint != 1)
			continue;
		if (!name) {
			cJSON * recipients = cJSON_GetObjectItem(channel, "recipients");
			if (!cJSON_IsArray(recipients))
				continue;
			cJSON * rec = NULL;
			name = calloc(1, 1);
			cJSON_ArrayForEach(rec, recipients) {
				char * recipient = cJSON_GetStringValue(cJSON_GetObjectItem(rec, "username"));
				if (!recipient)
					continue;
				name = realloc(name, strlen(name)+strlen(recipient)+3); /* +3: comma, space, null character */
				strcat(name, recipient);
				strcat(name, ", ");
			}
			name[strlen(name)-2] = '\0'; /* odrežemo zadnja dva znaka; vejico in presledek I: */
		}
		int slowmode = 0;
		if (cJSON_IsNumber(jsonslowmode))
			slowmode = jsonslowmode->valueint;
		if (!topic)
			topic = "";
		unsigned long long int idull = strtoull(id, NULL, 10);
		for (int i = 0; i < g->channels_sizeof; i++)
			if (idull == g->channels[i]->id) {
				skip++;
				break;
			}
		if (skip) continue;
		g->channels = realloc(g->channels, sizeof(struct dc_channel *)*++g->channels_sizeof);
		g->channels[g->channels_sizeof-1] = calloc(1, sizeof(struct dc_channel));
		g->channels[g->channels_sizeof-1]->name = malloc(strlen(name)+1);
		strcpy(g->channels[g->channels_sizeof-1]->name, name);
		g->channels[g->channels_sizeof-1]->topic = malloc(strlen(topic)+1);
		strcpy(g->channels[g->channels_sizeof-1]->topic, topic);
		g->channels[g->channels_sizeof-1]->id = strtoull(id, NULL, 10);
		g->channels[g->channels_sizeof-1]->guild = g;
		g->channels[g->channels_sizeof-1]->slowmode = slowmode;
	}
	if (DC_CUE(c, c->guilds_lock)) {rs = -8; goto rc;}
	rc:
	cJSON_Delete(json); json = NULL;
	return rs;
}
int dc_send_message (struct dc_message * m) { /* nolock - once message is appended to the c->sent_messages queue you must not remove it or alter it */
	int rs = 1;
	if (!m)
		return -1;
	struct dc_client * c = m->channel->guild->client; /* segfault senpai */
	if (!c)
		return -2;
	if (c->discriminator < 0) {
		if ((rs = dc_login(c)) < 0) {
			DC_CLIENT_ERROR(c, "dc_login(c) " DC_I18N_FAILED " (%d)", rs);
			return -3;
		} else rs = 1;
	}
	cJSON * json = cJSON_CreateObject();
	cJSON * nons = cJSON_CreateNumber(rand());
	cJSON_AddItemToObject(json, "nonce", nons);
	cJSON * content = cJSON_CreateString(m->content ? m->content : "dc_send_message(): !m->content");
	cJSON_AddItemToObject(json, "content", content);
	cJSON * tts = m->tts ? cJSON_CreateTrue() : cJSON_CreateFalse();
	cJSON_AddItemToObject(json, "tts", tts);
	char * body = cJSON_Print(json);
	if (!body) {
		DC_CLIENT_ERROR(c, "cJSON_Print " DC_I18N_FAILED);
		rs = -4;
		goto rc;
	}
	cJSON_Delete(json); json = NULL;
	/* {content: "yeet", nonce: "820762917392613376", tts: false} */
	json = DC_CAPI(c, body, DC_API_PREFIX "channels/%llu/messages", m->channel->id); /* ids are only written by api thread, nolock */
	if (!json) {
		DC_CLIENT_ERROR(c, "DC_CAPI channels/%llu/messages " DC_I18N_FAILED, m->channel->id);
		rs = -5;
		goto rc;
	}
	char * discriminator = cJSON_GetStringValue(cJSON_GetObjectItem2(json, "author", "discriminator"));
	if (!discriminator) {
		DC_CLIENT_ERROR(c, "!discriminator");
		rs = -6;
		goto rc;
	}
	m->discriminator = strtol(discriminator, NULL, 10);
	char * username = cJSON_GetStringValue(cJSON_GetObjectItem2(json, "author", "username"));
	if (!username) {
		DC_CLIENT_ERROR(c, "!username");
		rs = -6;
		goto rc;
	}
	m->username = malloc(strlen(username)+1);
	strcpy(m->username, username); /* we don't directly point as that changes when we delete */
	rc:
	free(body); body = NULL;
	cJSON_Delete(json); json = NULL;
	c->last_sent_message = time(NULL);
	return rs;
}
int dc_fetch_messages (struct dc_channel * ch) {
	int rs = 1;
	struct tm tm;
	if (!ch || !ch->id)
		return -1;
	struct dc_guild * g = ch->guild;
	if (!g || !g->client)
		return -2;
	struct dc_client * c = g->client;
	if (!c)
		return -3;
	if (c->discriminator < 0) {
		if ((rs = dc_login(c)) < 0) {
			DC_CLIENT_ERROR(c, "dc_login(c) " DC_I18N_FAILED " (%d)", rs);
			return -4;
		} else rs = 1;
	}
	cJSON * json = DC_CAPI(c, NULL, DC_API_PREFIX "channels/%llu/messages?limit=100&_=%d", ch->id, rand());
	if (!json) {
		DC_CLIENT_ERROR(c, "DC_CAPI channels/%llu/messages?limit=100&_=***rand()*** " DC_I18N_FAILED, ch->id);
		rs = -5;
		goto rc;
	}
	if (!cJSON_IsArray(json)) {
		DC_CLIENT_ERROR(c, "!cJSON_IsArray(json)");
		rs = -6;
		goto rc;
	}
	if (DC_CWLE(c, c->guilds_lock)) {rs = -7; goto rc;} /* we lock all guilds of a client when writing messages */
	cJSON * message = NULL;
	int msgs = 0;
	cJSON_ArrayForEach(message, json) {
		int skip = 0;
		char * timestamp = cJSON_GetStringValue(cJSON_GetObjectItem(message, "timestamp"));
		char * content = cJSON_GetStringValue(cJSON_GetObjectItem(message, "content"));
		char * id = cJSON_GetStringValue(cJSON_GetObjectItem(message, "id"));
		char * discriminator = cJSON_GetStringValue(cJSON_GetObjectItem2(message, "author", "discriminator"));
		char * username = cJSON_GetStringValue(cJSON_GetObjectItem2(message, "author", "username"));
		char * attachment = NULL;
		cJSON * attachmentj = NULL;
		cJSON * attachments = cJSON_GetObjectItem(message, "attachments");
		cJSON_ArrayForEach(attachmentj, attachments)
			if ((attachment = cJSON_GetStringValue(cJSON_GetObjectItem(attachmentj, "url"))))
				break; /* we only extract the first attachment */
		if (!id || !timestamp || (!content && !attachment) || !username || !discriminator) {
			DC_CLIENT_ERROR(c, "!id || (!timestamp && !attachment) || !content || !username || discriminator < 0");
			continue;
		}
		int kratekts = 0;
		if (strlen(timestamp) < 26) {
			if (strlen(timestamp) == strlen("2021-03-21T13:54:17+00:00")) {
				kratekts = 1;
			} else {
				char * jsonstring = cJSON_Print(message);
				DC_CLIENT_ERROR(c, "strlen(timestamp) < 26, json = %s", jsonstring);
				free(jsonstring);
				jsonstring = NULL;
				continue;
			}
		}
		if (!kratekts) {
			for (int i = 20; i <= 25; i++)
				timestamp[i] = 'X'; /* because strptime does not have wildcard support and those numbers are sub-second fractions */
			if (!strptime(timestamp, DC_TIMESTAMP_FORMAT, &tm)) {
				DC_CLIENT_ERROR(c, "!strptime(timestamp, DC_TIMESTAMP_FORMAT, &tm), timestamp = %s", timestamp);
				continue;
			}
		} else { /* if there are no subsecond fractions */
			if (!strptime(timestamp, DC_SHORTTIMESTAMP_FORMAT, &tm)) {
				DC_CLIENT_ERROR(c, "!strptime(timestamp, DC_SHORTTIMESTAMP_FORMAT, &tm), timestamp = %s", timestamp);
				continue;
			}
		}
		unsigned long long int idull = strtoull(id, NULL, 10);
		for (int i = 0; i < ch->messages_sizeof; i++)
			if (idull == ch->messages[i]->id) {
				skip++;
				break; /* remove duplicates */
			}
		if (skip) continue;
		ch->messages = realloc(ch->messages, sizeof(struct dc_message *)*++ch->messages_sizeof);
#define DC_FMTM /* fetch messages this message */ ch->messages[ch->messages_sizeof-1]
		/* DC_CLIENT_ERROR(c, "recvd msg %llu", idull); */ /* remember: continue in a nested forloop is not useful in some cases (: */
		DC_FMTM = calloc(1, sizeof(struct dc_message));
		DC_FMTM->time = mktime(&tm);
		if (content)
			strcpy(DC_FMTM->content = malloc(strlen(content)+1), content);
		if (attachment)
			strcpy(DC_FMTM->attachment = malloc(strlen(attachment)+1), attachment);
		DC_FMTM->username = malloc(strlen(username)+1);
		strcpy(DC_FMTM->username, username);
		DC_FMTM->id = idull;
		DC_FMTM->discriminator = strtol(discriminator, NULL, 10);
		DC_FMTM->channel = ch;
		msgs++;
	}
	qsort(ch->messages, ch->messages_sizeof, sizeof(struct dc_message *), dc_message_compare); /* we sort so that present messages are in the start of the array and old messages are to the end of the array */
	if (DC_CUE(c, c->guilds_lock)) {rs = -8; goto rc;}
	if (msgs > 0)
		rs = msgs;
	rc:
	cJSON_Delete(json); json = NULL;
	return rs;
}
struct dc_thread_control {
	unsigned short int power_api; /* 1 if the thread should run, set it to 2 for the thread to return at the end of the loop */
	unsigned short int power_ui; /* so same struct can be used for both api and ui thread, they have individual power switches */
	/* powers have a default state of 0, in this state, the thread should be paused, before first clearing 0 the thread should not do anything! */
	struct dc_client ** clients; /* "array" of pointers to clients the thread should manage, ONLY ONE dc_api_thread PER PROCESS! */
	_Atomic(size_t) clients_sizeof; /* noapiw */
	pthread_rwlock_t * clients_lock; /* do not lock yet. you can use safe-appending from the ui thread by never reallocing the pointers and only incrementing _sizeof - don't even init&destroy*/
	FILE * cout; /* file descriptor of the terminal for the ui thread to write to */
	FILE * cin; /* file descriptor of the terminal for the ui thread to read from */
	FILE * cerr; /* file descriptor of the terminal for the ui thread to write error messages to */
};
int dc_api_thread (struct dc_thread_control * t) { /* updates messages and sends messages when they are in the outbox */
	while (!t->power_api) usleep(250000); /* so as to not make the switcher go bankrupt */
	curl_global_init(CURL_GLOBAL_ALL);
	/* if (pthread_rwlock_wrlock(t->clients_lock))
		return -1; */ /* clients are not locked yet */
	for (int i = 0; i < t->clients_sizeof && t->power_api != 2; i++)
		dc_login(t->clients[i]);
	while (t->power_api != 2) { /* as there's only one api thread and only it modifies things that need a guilds_lock, it's okay to */
		for (int i = 0; i < t->clients_sizeof; i++) { /* perform such unsafe loops without read-locking. note that you will deadlock */
			if (t->clients[i]->discriminator < -1) /* should you attempt to read-lock guilds_lock. */
				continue; /* the only exception is sent_messages that is write-locked */
			if (t->clients[i]->guilds_sizeof <= 1 /* || !(rand() % 1000) */) /* guild 0 is a virtual ZS guild */
				dc_fetch_guilds(t->clients[i]);
			for (int j = 0; j < t->clients[i]->guilds_sizeof; j++) {
				if (!t->clients[i]->guilds[j]->channels_sizeof /*|| !(rand() % 100)*/) /* roughly every 100+inf cycles we'll update channels */
					dc_fetch_channels(t->clients[i]->guilds[j]);
			}
			for (int k = 0; k < t->clients[i]->guilds_sizeof; k++)
				for (int l = 0; l < t->clients[i]->guilds[k]->channels_sizeof; l++)
					if (t->clients[i]->guilds[k]->channels[l]->joined && !(rand() % 10)) /* roughly every 10 cycles we'll update messages in the joined channels */
						if (dc_fetch_messages(t->clients[i]->guilds[k]->channels[l]) > 0)
							t->clients[i]->newmessages++;
			if (DC_CWLE(t->clients[i], t->clients[i]->sent_messages_lock)) continue;
			if (t->clients[i]->sent_messages_sizeof > 0) {
				struct dc_message * msg2send = t->clients[i]->sent_messages[0];
				if (dc_send_message(msg2send) > 0) {
					/* DC_CWLE(t->clients[i], t->clients[i]->guilds_lock);
					msg2send->channel->messages = realloc(msg2send->channel->messages, sizeof(struct dc_message *)*++msg2send->channel->messages_sizeof);
					msg2send->channel->messages[msg2send->channel->messages_sizeof-1] = msg2send;
					DC_CUE(t->clients[i], t->clients[i]->guilds_lock); */ /* we will no longer do this, let the thread fetch the msg */
					for (int j = 0; j < t->clients[i]->sent_messages_sizeof-1; j++) /* shift, we removed one from the start */
						t->clients[i]->sent_messages[j] = t->clients[i]->sent_messages[j+1];
					t->clients[i]->sent_messages_sizeof--;
				}
			}
			DC_CUE(t->clients[i], t->clients[i]->sent_messages_lock);
			while (!t->power_api) usleep(250000); /* so as to not make the switcher go bankrupt */
		}
		usleep(250000);
	}
	curl_global_cleanup();
	/* if (pthread_rwlock_unlock(t->clients_lock))
		return -2; */
	return 1;
} /* the thread shall use mutexes when doing things with shared memory - client structs */