/* Copyright (c) 2011-2017 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "str.h"
#include "ioloop.h"
#include "istream.h"
#include "istream-concat.h"
#include "istream-header-filter.h"
#include "message-header-parser.h"
#include "imap-arg.h"
#include "imap-date.h"
#include "imap-quote.h"
#include "imap-resp-code.h"
#include "imapc-client.h"
#include "imapc-mail.h"
#include "imapc-storage.h"

static void imapc_mail_set_failure(struct imapc_mail *mail,
				   const struct imapc_command_reply *reply)
{
	struct imapc_mailbox *mbox =
		(struct imapc_mailbox *)mail->imail.mail.mail.box;

	mail->last_fetch_reply = p_strdup(mail->imail.mail.pool, reply->text_full);

	switch (reply->state) {
	case IMAPC_COMMAND_STATE_OK:
		break;
	case IMAPC_COMMAND_STATE_NO:
		if (!IMAPC_BOX_HAS_FEATURE(mbox, IMAPC_FEATURE_FETCH_FIX_BROKEN_MAILS)) {
			/* fetch-fix-broken-mails feature disabled -
			   fail any mails with missing replies */
			break;
		}
		if (reply->resp_text_key != NULL &&
		    (strcasecmp(reply->resp_text_key, IMAP_RESP_CODE_SERVERBUG) == 0 ||
		     strcasecmp(reply->resp_text_key, IMAP_RESP_CODE_LIMIT) == 0)) {
			/* this is a temporary error, retrying should work.
			   Yahoo sends * BYE +
			   NO [LIMIT] UID FETCH Rate limit hit. */
		} else {
			/* hopefully this is a permanent failure */
			mail->fetch_ignore_if_missing = TRUE;
		}
		break;
	case IMAPC_COMMAND_STATE_BAD:
	case IMAPC_COMMAND_STATE_DISCONNECTED:
		mail->fetch_failed = TRUE;
		break;
	}
}

static void
imapc_mail_fetch_callback(const struct imapc_command_reply *reply,
			  void *context)
{
	struct imapc_fetch_request *request = context;
	struct imapc_fetch_request *const *requests;
	struct imapc_mail *const *mailp;
	struct imapc_mailbox *mbox = NULL;
	unsigned int i, count;

	array_foreach(&request->mails, mailp) {
		struct imapc_mail *mail = *mailp;

		i_assert(mail->fetch_count > 0);
		imapc_mail_set_failure(mail, reply);
		if (--mail->fetch_count == 0)
			mail->fetching_fields = 0;
		pool_unref(&mail->imail.mail.pool);
		mbox = (struct imapc_mailbox *)mail->imail.mail.mail.box;
	}
	i_assert(mbox != NULL);

	requests = array_get(&mbox->fetch_requests, &count);
	for (i = 0; i < count; i++) {
		if (requests[i] == request) {
			array_delete(&mbox->fetch_requests, i, 1);
			break;
		}
	}
	i_assert(i < count);

	array_free(&request->mails);
	i_free(request);

	if (reply->state == IMAPC_COMMAND_STATE_OK)
		;
	else if (reply->state == IMAPC_COMMAND_STATE_NO) {
		imapc_copy_error_from_reply(mbox->storage, MAIL_ERROR_PARAMS,
					    reply);
	} else if (reply->state == IMAPC_COMMAND_STATE_DISCONNECTED) {
		/* The disconnection message was already logged */
		mail_storage_set_internal_error(&mbox->storage->storage);
	} else {
		mail_storage_set_critical(&mbox->storage->storage,
			"imapc: Mail FETCH failed: %s", reply->text_full);
	}
	imapc_client_stop(mbox->storage->client->client);
}

static bool
headers_have_subset(const char *const *superset, const char *const *subset)
{
	unsigned int i;

	if (superset == NULL)
		return FALSE;
	if (subset != NULL) {
		for (i = 0; subset[i] != NULL; i++) {
			if (!str_array_icase_find(superset, subset[i]))
				return FALSE;
		}
	}
	return TRUE;
}

static const char *const *
headers_merge(pool_t pool, const char *const *h1, const char *const *h2)
{
	ARRAY_TYPE(const_string) headers;
	const char *value;
	unsigned int i;

	p_array_init(&headers, pool, 16);
	if (h1 != NULL) {
		for (i = 0; h1[i] != NULL; i++) {
			value = p_strdup(pool, h1[i]);
			array_append(&headers, &value, 1);
		}
	}
	if (h2 != NULL) {
		for (i = 0; h2[i] != NULL; i++) {
			if (h1 == NULL || !str_array_icase_find(h1, h2[i])) {
				value = p_strdup(pool, h2[i]);
				array_append(&headers, &value, 1);
			}
		}
	}
	array_append_zero(&headers);
	return array_idx(&headers, 0);
}

static bool
imapc_mail_try_merge_fetch(struct imapc_mailbox *mbox, string_t *str)
{
	const char *s1 = str_c(str);
	const char *s2 = str_c(mbox->pending_fetch_cmd);
	const char *p1, *p2;

	i_assert(strncmp(s1, "UID FETCH ", 10) == 0);
	i_assert(strncmp(s2, "UID FETCH ", 10) == 0);

	/* skip over UID range */
	p1 = strchr(s1+10, ' ');
	p2 = strchr(s2+10, ' ');

	if (null_strcmp(p1, p2) != 0)
		return FALSE;
	/* append the new UID to the pending FETCH UID range */
	str_truncate(str, p1-s1);
	str_insert(mbox->pending_fetch_cmd, p2-s2, ",");
	str_insert(mbox->pending_fetch_cmd, p2-s2+1, str_c(str) + 10);
	return TRUE;
}

static void
imapc_mail_delayed_send_or_merge(struct imapc_mail *mail, string_t *str)
{
	struct imapc_mailbox *mbox =
		(struct imapc_mailbox *)mail->imail.mail.mail.box;

	if (mbox->pending_fetch_request != NULL &&
	    !imapc_mail_try_merge_fetch(mbox, str)) {
		/* send the previous FETCH and create a new one */
		imapc_mail_fetch_flush(mbox);
	}
	if (mbox->pending_fetch_request == NULL) {
		mbox->pending_fetch_request =
			i_new(struct imapc_fetch_request, 1);
		i_array_init(&mbox->pending_fetch_request->mails, 4);
		i_assert(mbox->pending_fetch_cmd->used == 0);
		str_append_str(mbox->pending_fetch_cmd, str);
	}
	array_append(&mbox->pending_fetch_request->mails, &mail, 1);

	if (mbox->to_pending_fetch_send == NULL &&
	    array_count(&mbox->pending_fetch_request->mails) >
	    			mbox->box.storage->set->mail_prefetch_count) {
		/* we're now prefetching the maximum number of mails. this
		   most likely means that we need to flush out the command now
		   before sending anything else. delay it a little bit though
		   in case the sending code doesn't actually use
		   mail_prefetch_count and wants to fetch more.

		   note that we don't want to add this timeout too early,
		   because we want to optimize the maximum number of messages
		   placed into a single FETCH. even without timeout the command
		   gets flushed by imapc_mail_fetch() call. */
		mbox->to_pending_fetch_send =
			timeout_add_short(0, imapc_mail_fetch_flush, mbox);
	}
}

static int
imapc_mail_send_fetch(struct mail *_mail, enum mail_fetch_field fields,
		      const char *const *headers)
{
	struct imapc_mail *mail = (struct imapc_mail *)_mail;
	struct imapc_mailbox *mbox = (struct imapc_mailbox *)_mail->box;
	struct mail_index_view *view;
	string_t *str;
	uint32_t seq;
	unsigned int i;

	if (_mail->lookup_abort != MAIL_LOOKUP_ABORT_NEVER) {
		mail_set_aborted(_mail);
		return -1;
	}
	_mail->mail_stream_opened = TRUE;

	/* drop any fields that we may already be fetching currently */
	fields &= ~mail->fetching_fields;
	if (headers_have_subset(mail->fetching_headers, headers))
		headers = NULL;
	if (fields == 0 && headers == NULL)
		return mail->fetch_sent ? 0 : 1;

	if (!_mail->saving) {
		/* if we already know that the mail is expunged,
		   don't try to FETCH it */
		view = mbox->delayed_sync_view != NULL ?
			mbox->delayed_sync_view : mbox->box.view;
		if (!mail_index_lookup_seq(view, _mail->uid, &seq) ||
		    mail_index_is_expunged(view, seq)) {
			mail_set_expunged(_mail);
			return -1;
		}
	} else if (mbox->client_box == NULL) {
		/* opened as save-only. we'll need to fetch the mail,
		   so actually SELECT/EXAMINE the mailbox */
		i_assert(mbox->box.opened);

		if (imapc_mailbox_select(mbox) < 0)
			return -1;
	}

	if ((fields & MAIL_FETCH_STREAM_BODY) != 0)
		fields |= MAIL_FETCH_STREAM_HEADER;

	str = t_str_new(64);
	str_printfa(str, "UID FETCH %u (", _mail->uid);
	if ((fields & MAIL_FETCH_RECEIVED_DATE) != 0)
		str_append(str, "INTERNALDATE ");
	if ((fields & (MAIL_FETCH_PHYSICAL_SIZE | MAIL_FETCH_VIRTUAL_SIZE)) != 0)
		str_append(str, "RFC822.SIZE ");
	if ((fields & MAIL_FETCH_GUID) != 0) {
		str_append(str, mbox->guid_fetch_field_name);
		str_append_c(str, ' ');
	}

	if ((fields & MAIL_FETCH_STREAM_BODY) != 0) {
		if (!IMAPC_BOX_HAS_FEATURE(mbox, IMAPC_FEATURE_ZIMBRA_WORKAROUNDS))
			str_append(str, "BODY.PEEK[] ");
		else {
			/* BODY.PEEK[] can return different headers than
			   BODY.PEEK[HEADER] (e.g. invalid 8bit chars replaced
			   with '?' in HEADER) - this violates IMAP protocol
			   and messes up dsync since it sometimes fetches the
			   full body and sometimes only the headers. */
			str_append(str, "BODY.PEEK[HEADER] BODY.PEEK[TEXT] ");
		}
	} else if ((fields & MAIL_FETCH_STREAM_HEADER) != 0)
		str_append(str, "BODY.PEEK[HEADER] ");
	else if (headers != NULL) {
		mail->fetching_headers =
			headers_merge(mail->imail.mail.data_pool, headers,
				      mail->fetching_headers);
		str_append(str, "BODY.PEEK[HEADER.FIELDS (");
		for (i = 0; mail->fetching_headers[i] != NULL; i++) {
			if (i > 0)
				str_append_c(str, ' ');
			imap_append_astring(str, mail->fetching_headers[i]);
		}
		str_append(str, ")] ");
		mail->header_list_fetched = FALSE;
	}
	str_truncate(str, str_len(str)-1);
	str_append_c(str, ')');

	pool_ref(mail->imail.mail.pool);
	mail->fetching_fields |= fields;
	mail->fetch_count++;
	mail->fetch_sent = FALSE;
	mail->fetch_failed = FALSE;

	imapc_mail_delayed_send_or_merge(mail, str);
	return 1;
}

static void imapc_mail_cache_get(struct imapc_mail *mail,
				 struct imapc_mail_cache *cache)
{
	if (mail->body_fetched)
		return;

	if (cache->fd != -1) {
		mail->fd = cache->fd;
		mail->imail.data.stream =
			i_stream_create_fd(mail->fd, 0, FALSE);
		cache->fd = -1;
	} else if (cache->buf != NULL) {
		mail->body = cache->buf;
		mail->imail.data.stream =
			i_stream_create_from_data(mail->body->data,
						  mail->body->used);
		cache->buf = NULL;
	} else {
		return;
	}
	mail->header_fetched = TRUE;
	mail->body_fetched = TRUE;
	imapc_mail_init_stream(mail);
}

static enum mail_fetch_field
imapc_mail_get_wanted_fetch_fields(struct imapc_mail *mail)
{
	struct imapc_mailbox *mbox =
		(struct imapc_mailbox *)mail->imail.mail.mail.box;
	struct index_mail_data *data = &mail->imail.data;
	enum mail_fetch_field fields = 0;

	if ((data->wanted_fields & MAIL_FETCH_RECEIVED_DATE) != 0 &&
	    data->received_date == (time_t)-1)
		fields |= MAIL_FETCH_RECEIVED_DATE;
	if ((data->wanted_fields & MAIL_FETCH_SAVE_DATE) != 0 &&
	    data->save_date == (time_t)-1 && data->received_date == (time_t)-1)
		fields |= MAIL_FETCH_RECEIVED_DATE;
	if ((data->wanted_fields & (MAIL_FETCH_PHYSICAL_SIZE |
				    MAIL_FETCH_VIRTUAL_SIZE)) != 0 &&
	    data->physical_size == (uoff_t)-1 &&
	    IMAPC_BOX_HAS_FEATURE(mbox, IMAPC_FEATURE_RFC822_SIZE))
		fields |= MAIL_FETCH_PHYSICAL_SIZE | MAIL_FETCH_VIRTUAL_SIZE;
	if ((data->wanted_fields & MAIL_FETCH_GUID) != 0 &&
	    data->guid == NULL && mbox->guid_fetch_field_name != NULL)
		fields |= MAIL_FETCH_GUID;

	if (data->stream == NULL && data->access_part != 0) {
		if ((data->access_part & (READ_BODY | PARSE_BODY)) != 0)
			fields |= MAIL_FETCH_STREAM_BODY;
		else
			fields |= MAIL_FETCH_STREAM_HEADER;
	}
	return fields;
}

bool imapc_mail_prefetch(struct mail *_mail)
{
	struct imapc_mail *mail = (struct imapc_mail *)_mail;
	struct imapc_mailbox *mbox = (struct imapc_mailbox *)_mail->box;
	struct index_mail_data *data = &mail->imail.data;
	enum mail_fetch_field fields;

	if (mbox->prev_mail_cache.uid == _mail->uid)
		imapc_mail_cache_get(mail, &mbox->prev_mail_cache);
	/* try to get as much from cache as possible */
	imapc_mail_update_access_parts(&mail->imail);

	fields = imapc_mail_get_wanted_fetch_fields(mail);
	if (fields != 0 ||
	    (data->wanted_headers != NULL &&
	     !imapc_mail_has_headers_in_cache(&mail->imail, data->wanted_headers))) T_BEGIN {
		if (imapc_mail_send_fetch(_mail, fields,
					  data->wanted_headers == NULL ? NULL :
					  data->wanted_headers->name) > 0)
			mail->imail.data.prefetch_sent = TRUE;
	} T_END;
	return !mail->imail.data.prefetch_sent;
}

static bool
imapc_mail_have_fields(struct imapc_mail *imail, enum mail_fetch_field fields)
{
	if ((fields & MAIL_FETCH_RECEIVED_DATE) != 0) {
		if (imail->imail.data.received_date == (time_t)-1)
			return FALSE;
		fields &= ~MAIL_FETCH_RECEIVED_DATE;
	}
	if ((fields & (MAIL_FETCH_PHYSICAL_SIZE | MAIL_FETCH_VIRTUAL_SIZE)) != 0) {
		if (imail->imail.data.physical_size == (uoff_t)-1)
			return FALSE;
		fields &= ~(MAIL_FETCH_PHYSICAL_SIZE | MAIL_FETCH_VIRTUAL_SIZE);
	}
	if ((fields & MAIL_FETCH_GUID) != 0) {
		if (imail->imail.data.guid == NULL)
			return FALSE;
		fields &= ~MAIL_FETCH_GUID;
	}
	if ((fields & (MAIL_FETCH_STREAM_HEADER |
		       MAIL_FETCH_STREAM_BODY)) != 0) {
		if (imail->imail.data.stream == NULL)
			return FALSE;
		fields &= ~(MAIL_FETCH_STREAM_HEADER | MAIL_FETCH_STREAM_BODY);
	}
	i_assert(fields == 0);
	return TRUE;
}

int imapc_mail_fetch(struct mail *_mail, enum mail_fetch_field fields,
		     const char *const *headers)
{
	struct imapc_mail *imail = (struct imapc_mail *)_mail;
	struct imapc_mailbox *mbox =
		(struct imapc_mailbox *)_mail->box;
	int ret;

	if ((fields & MAIL_FETCH_GUID) != 0 &&
	    mbox->guid_fetch_field_name == NULL) {
		mail_storage_set_error(_mail->box->storage,
			MAIL_ERROR_NOTPOSSIBLE,
			"Message GUID not available in this server");
		return -1;
	}
	if (_mail->saving) {
		mail_storage_set_error(_mail->box->storage,
			MAIL_ERROR_NOTPOSSIBLE,
			"Attempting to issue FETCH for a mail not yet committed");
		return -1;
	}

	fields |= imapc_mail_get_wanted_fetch_fields(imail);
	T_BEGIN {
		ret = imapc_mail_send_fetch(_mail, fields, headers);
	} T_END;
	if (ret < 0)
		return -1;

	/* we'll continue waiting until we've got all the fields we wanted,
	   or until all FETCH replies have been received (i.e. some FETCHes
	   failed) */
	if (ret > 0)
		imapc_mail_fetch_flush(mbox);
	while (imail->fetch_count > 0 &&
	       (!imapc_mail_have_fields(imail, fields) ||
		!imail->header_list_fetched)) {
		imapc_mailbox_run_nofetch(mbox);
	}
	if (imail->fetch_failed) {
		mail_storage_set_internal_error(&mbox->storage->storage);
		return -1;
	}
	return 0;
}

void imapc_mail_fetch_flush(struct imapc_mailbox *mbox)
{
	struct imapc_command *cmd;
	struct imapc_mail *const *mailp;

	if (mbox->pending_fetch_request == NULL) {
		i_assert(mbox->to_pending_fetch_send == NULL);
		return;
	}

	array_foreach(&mbox->pending_fetch_request->mails, mailp)
		(*mailp)->fetch_sent = TRUE;

	cmd = imapc_client_mailbox_cmd(mbox->client_box,
				       imapc_mail_fetch_callback,
				       mbox->pending_fetch_request);
	imapc_command_set_flags(cmd, IMAPC_COMMAND_FLAG_RETRIABLE);
	array_append(&mbox->fetch_requests, &mbox->pending_fetch_request, 1);

	imapc_command_send(cmd, str_c(mbox->pending_fetch_cmd));

	mbox->pending_fetch_request = NULL;
	if (mbox->to_pending_fetch_send != NULL)
		timeout_remove(&mbox->to_pending_fetch_send);
	str_truncate(mbox->pending_fetch_cmd, 0);
}

static bool imapc_find_lfile_arg(const struct imapc_untagged_reply *reply,
				 const struct imap_arg *arg, int *fd_r)
{
	const struct imap_arg *list;
	unsigned int i, count;

	for (i = 0; i < reply->file_args_count; i++) {
		const struct imapc_arg_file *farg = &reply->file_args[i];

		if (farg->parent_arg == arg->parent &&
		    imap_arg_get_list_full(arg->parent, &list, &count) &&
		    farg->list_idx < count && &list[farg->list_idx] == arg) {
			*fd_r = farg->fd;
			return TRUE;
		}
	}
	return FALSE;
}

static void imapc_stream_filter(struct istream **input)
{
	static const char *imapc_hide_headers[] = {
		/* Added by MS Exchange 2010 when \Flagged flag is set.
		   This violates IMAP guarantee of messages being immutable. */
		"X-Message-Flag"
	};
	struct istream *filter_input;

	filter_input = i_stream_create_header_filter(*input,
		HEADER_FILTER_EXCLUDE,
		imapc_hide_headers, N_ELEMENTS(imapc_hide_headers),
		*null_header_filter_callback, (void *)NULL);
	i_stream_unref(input);
	*input = filter_input;
}

void imapc_mail_init_stream(struct imapc_mail *mail)
{
	struct index_mail *imail = &mail->imail;
	struct mail *_mail = &imail->mail.mail;
	struct imapc_mailbox *mbox = (struct imapc_mailbox *)_mail->box;
	struct istream *input;
	uoff_t size;
	int ret;

	i_stream_set_name(imail->data.stream,
			  t_strdup_printf("imapc mail uid=%u", _mail->uid));
	index_mail_set_read_buffer_size(_mail, imail->data.stream);

	if (!IMAPC_BOX_HAS_FEATURE(mbox, IMAPC_FEATURE_RFC822_SIZE)) {
		/* enable filtering only when we're not passing through
		   RFC822.SIZE. otherwise we'll get size mismatches. */
		imapc_stream_filter(&imail->data.stream);
	}
	if (imail->mail.v.istream_opened != NULL) {
		if (imail->mail.v.istream_opened(_mail,
						 &imail->data.stream) < 0) {
			index_mail_close_streams(imail);
			return;
		}
	} else if (mail->body_fetched) {
		ret = i_stream_get_size(imail->data.stream, TRUE, &size);
		if (ret < 0) {
			index_mail_close_streams(imail);
			return;
		}
		i_assert(ret != 0);
		imail->data.physical_size = size;
		/* we'll assume that the remote server is working properly and
		   sending CRLF linefeeds */
		imail->data.virtual_size = size;
	}

	imail->data.stream_has_only_header = !mail->body_fetched;
	if (index_mail_init_stream(imail, NULL, NULL, &input) < 0)
		index_mail_close_streams(imail);
}

static void
imapc_fetch_stream(struct imapc_mail *mail,
		   const struct imapc_untagged_reply *reply,
		   const struct imap_arg *arg,
		   bool have_header, bool have_body)
{
	struct index_mail *imail = &mail->imail;
	struct istream *hdr_stream = NULL;
	const char *value;
	int fd;

	if (imail->data.stream != NULL) {
		i_assert(mail->header_fetched);
		if (mail->body_fetched || !have_body)
			return;
		if (have_header) {
			/* replace the existing stream */
		} else if (mail->fd == -1) {
			/* append this body stream to the existing
			   header stream */
			hdr_stream = imail->data.stream;
			i_stream_ref(hdr_stream);
		} else {
			/* append this body stream to the existing
			   header stream. we'll need to recreate the stream
			   with autoclosed fd. */
			if (lseek(mail->fd, 0, SEEK_SET) < 0)
				i_error("lseek(imapc) failed: %m");
			hdr_stream = i_stream_create_fd_autoclose(&mail->fd, 0);
		}
		index_mail_close_streams(imail);
		if (mail->fd != -1) {
			if (close(mail->fd) < 0)
				i_error("close(imapc mail) failed: %m");
			mail->fd = -1;
		}
	} else {
		if (!have_header) {
			/* BODY.PEEK[TEXT] received - we can't currently handle
			   this before receiving BODY.PEEK[HEADER] reply */
			return;
		}
	}

	if (arg->type == IMAP_ARG_LITERAL_SIZE) {
		if (!imapc_find_lfile_arg(reply, arg, &fd)) {
			if (hdr_stream != NULL)
				i_stream_unref(&hdr_stream);
			return;
		}
		if ((fd = dup(fd)) == -1) {
			i_error("dup() failed: %m");
			if (hdr_stream != NULL)
				i_stream_unref(&hdr_stream);
			return;
		}
		mail->fd = fd;
		imail->data.stream = i_stream_create_fd(fd, 0, FALSE);
	} else {
		if (!imap_arg_get_nstring(arg, &value))
			value = NULL;
		if (value == NULL) {
			mail_set_expunged(&imail->mail.mail);
			if (hdr_stream != NULL)
				i_stream_unref(&hdr_stream);
			return;
		}
		if (mail->body == NULL) {
			mail->body = buffer_create_dynamic(default_pool,
							   arg->str_len + 1);
		} else if (!have_header && hdr_stream != NULL) {
			/* header is already in the buffer - add body now
			   without destroying the existing header data */
			i_stream_unref(&hdr_stream);
		} else {
			buffer_set_used_size(mail->body, 0);
		}
		buffer_append(mail->body, value, arg->str_len);
		imail->data.stream = i_stream_create_from_data(mail->body->data,
							       mail->body->used);
	}
	if (have_header)
		mail->header_fetched = TRUE;
	mail->body_fetched = have_body;

	if (hdr_stream != NULL) {
		struct istream *inputs[3];

		inputs[0] = hdr_stream;
		inputs[1] = imail->data.stream;
		inputs[2] = NULL;
		imail->data.stream = i_stream_create_concat(inputs);
		i_stream_unref(&inputs[0]);
		i_stream_unref(&inputs[1]);
	}

	imapc_mail_init_stream(mail);
}

static void
imapc_fetch_header_stream(struct imapc_mail *mail,
			  const struct imapc_untagged_reply *reply,
			  const struct imap_arg *args)
{
	const enum message_header_parser_flags hdr_parser_flags =
		MESSAGE_HEADER_PARSER_FLAG_SKIP_INITIAL_LWSP |
		MESSAGE_HEADER_PARSER_FLAG_DROP_CR;
	const struct imap_arg *hdr_list;
	struct mailbox_header_lookup_ctx *headers_ctx;
	struct message_header_parser_ctx *parser;
	struct message_header_line *hdr;
	struct istream *input;
	ARRAY_TYPE(const_string) hdr_arr;
	const char *value;
	int ret, fd;

	if (!imap_arg_get_list(args, &hdr_list))
		return;
	if (!imap_arg_atom_equals(args+1, "]"))
		return;
	args += 2;

	/* see if this is reply to the latest headers list request
	   (parse it even if it's not) */
	t_array_init(&hdr_arr, 16);
	while (imap_arg_get_astring(hdr_list, &value)) {
		array_append(&hdr_arr, &value, 1);
		hdr_list++;
	}
	if (hdr_list->type != IMAP_ARG_EOL)
		return;
	array_append_zero(&hdr_arr);

	if (headers_have_subset(array_idx(&hdr_arr, 0), mail->fetching_headers))
		mail->header_list_fetched = TRUE;

	if (args->type == IMAP_ARG_LITERAL_SIZE) {
		if (!imapc_find_lfile_arg(reply, args, &fd))
			return;
		input = i_stream_create_fd(fd, 0, FALSE);
	} else {
		if (!imap_arg_get_nstring(args, &value))
			return;
		if (value == NULL) {
			mail_set_expunged(&mail->imail.mail.mail);
			return;
		}
		input = i_stream_create_from_data(value, args->str_len);
	}

	headers_ctx = mailbox_header_lookup_init(mail->imail.mail.mail.box,
						 array_idx(&hdr_arr, 0));
	index_mail_parse_header_init(&mail->imail, headers_ctx);

	parser = message_parse_header_init(input, NULL, hdr_parser_flags);
	while ((ret = message_parse_header_next(parser, &hdr)) > 0)
		index_mail_parse_header(NULL, hdr, &mail->imail);
	i_assert(ret != 0);
	index_mail_parse_header(NULL, NULL, &mail->imail);
	message_parse_header_deinit(&parser);

	mailbox_header_lookup_unref(&headers_ctx);
	i_stream_destroy(&input);
}

void imapc_mail_fetch_update(struct imapc_mail *mail,
			     const struct imapc_untagged_reply *reply,
			     const struct imap_arg *args)
{
	struct imapc_mailbox *mbox =
		(struct imapc_mailbox *)mail->imail.mail.mail.box;
	const char *key, *value;
	unsigned int i;
	uoff_t size;
	time_t t;
	int tz;
	bool match = FALSE;

	for (i = 0; args[i].type != IMAP_ARG_EOL; i += 2) {
		if (!imap_arg_get_atom(&args[i], &key) ||
		    args[i+1].type == IMAP_ARG_EOL)
			break;

		if (strcasecmp(key, "BODY[]") == 0) {
			imapc_fetch_stream(mail, reply, &args[i+1], TRUE, TRUE);
			match = TRUE;
		} else if (strcasecmp(key, "BODY[HEADER]") == 0) {
			imapc_fetch_stream(mail, reply, &args[i+1], TRUE, FALSE);
			match = TRUE;
		} else if (strcasecmp(key, "BODY[TEXT]") == 0) {
			imapc_fetch_stream(mail, reply, &args[i+1], FALSE, TRUE);
			match = TRUE;
		} else if (strcasecmp(key, "BODY[HEADER.FIELDS") == 0) {
			imapc_fetch_header_stream(mail, reply, &args[i+1]);
			match = TRUE;
		} else if (strcasecmp(key, "INTERNALDATE") == 0) {
			if (imap_arg_get_astring(&args[i+1], &value) &&
			    imap_parse_datetime(value, &t, &tz))
				mail->imail.data.received_date = t;
			match = TRUE;
		} else if (strcasecmp(key, "RFC822.SIZE") == 0) {
			if (imap_arg_get_atom(&args[i+1], &value) &&
			    str_to_uoff(value, &size) == 0 &&
			    IMAPC_BOX_HAS_FEATURE(mbox, IMAPC_FEATURE_RFC822_SIZE))
				mail->imail.data.physical_size = size;
			match = TRUE;
		} else if (strcasecmp(key, "X-GM-MSGID") == 0 ||
			   strcasecmp(key, "X-GUID") == 0) {
			if (imap_arg_get_astring(&args[i+1], &value)) {
				mail->imail.data.guid =
					p_strdup(mail->imail.mail.pool, value);
			}
			match = TRUE;
		}
	}
	if (!match) {
		/* this is only a FETCH FLAGS update for the wanted mail */
	} else {
		imapc_client_stop(mbox->storage->client->client);
	}
}