/* Copyright (c) 2002-2018 Dovecot authors, see the included COPYING file */

#include "imap-common.h"
#include "str.h"
#include "istream.h"
#include "ostream.h"
#include "imap-resp-code.h"
#include "imap-util.h"
#include "imap-commands.h"
#include "imap-search-args.h"

#include <time.h>

#define COPY_CHECK_INTERVAL 100
#define MOVE_COMMIT_INTERVAL 1000

struct cmd_copy_context {
	struct client_command_context *cmd;
	struct mailbox *srcbox;
	struct mailbox *destbox;
	bool move;

	unsigned int copy_count;

	uint32_t uid_validity;
	ARRAY_TYPE(seq_range) src_uids;
	ARRAY_TYPE(seq_range) saved_uids;
	bool hide_saved_uids;

	const char *error_string;
	enum mail_error mail_error;
};

static int client_send_sendalive_if_needed(struct client *client)
{
	time_t now, last_io;
	int ret = 0;

	if (o_stream_get_buffer_used_size(client->output) != 0)
		return 0;

	now = time(NULL);
	last_io = I_MAX(client->last_input, client->last_output);
	if (now - last_io > MAIL_STORAGE_STAYALIVE_SECS) {
		o_stream_nsend_str(client->output, "* OK Hang in there..\r\n");
		/* make sure it doesn't get stuck on the corked stream */
		if (o_stream_uncork_flush(client->output) < 0)
			ret = -1;
		o_stream_cork(client->output);
		client->last_output = now;
	}
	return ret;
}

static void copy_update_trashed(struct client *client, struct mailbox *box,
				unsigned int count)
{
	const struct mailbox_settings *set;

	set = mailbox_settings_find(mailbox_get_namespace(box),
				    mailbox_get_vname(box));
	if (set != NULL && set->special_use[0] != '\0' &&
	    str_array_icase_find(t_strsplit_spaces(set->special_use, " "),
				 "\\Trash"))
		client->trashed_count += count;
}

static bool client_is_disconnected(struct client *client)
{
	if (client->fd_in == STDIN_FILENO) {
		/* Skip this check for stdio clients. It's often used in
		   testing where the test expects that all commands will be
		   run even though stdin already has reached EOF. */
		return FALSE;
	}
	ssize_t bytes = i_stream_read(client->input);
	if (bytes == -1)
		return TRUE;
	if (bytes != 0)
		i_stream_set_input_pending(client->input, TRUE);
	return FALSE;
}

static int fetch_and_copy(struct cmd_copy_context *copy_ctx,
			  const struct mail_search_args *uid_search_args)
{
	struct client *client = copy_ctx->cmd->client;
	struct mailbox_transaction_context *t, *src_trans;
	struct mail_search_args *search_args;
	struct mail_search_context *search_ctx;
	struct mail_save_context *save_ctx;
	struct mail *mail;
	const char *cmd_reason;
	struct mail_transaction_commit_changes changes;
	ARRAY_TYPE(seq_range) src_uids;
	int ret;

	/* convert uidset to seqset */
	search_args = mail_search_args_dup(uid_search_args);
	mail_search_args_init(search_args, copy_ctx->srcbox, TRUE, NULL);
	/* make sure the number of messages didn't already change */
	i_assert(uid_search_args->args->type == SEARCH_UIDSET);
	i_assert(search_args->args->type == SEARCH_SEQSET ||
		 (search_args->args->type == SEARCH_ALL &&
		  search_args->args->match_not));
	if (search_args->args->type != SEARCH_SEQSET ||
	    seq_range_count(&search_args->args->value.seqset) !=
	    seq_range_count(&uid_search_args->args->value.seqset)) {
		mail_search_args_unref(&search_args);
		return 0;
	}

	i_assert(o_stream_is_corked(client->output) ||
		 client->output->stream_errno != 0);

	cmd_reason = imap_client_command_get_reason(copy_ctx->cmd);
	t = mailbox_transaction_begin(copy_ctx->destbox,
				      MAILBOX_TRANSACTION_FLAG_EXTERNAL |
				      MAILBOX_TRANSACTION_FLAG_ASSIGN_UIDS,
				      cmd_reason);
	/* Refresh source index so expunged mails will be noticed */
	src_trans = mailbox_transaction_begin(copy_ctx->srcbox,
					      MAILBOX_TRANSACTION_FLAG_REFRESH,
					      cmd_reason);
	search_ctx = mailbox_search_init(src_trans, search_args,
					 NULL, 0, NULL);
	mail_search_args_unref(&search_args);

	t_array_init(&src_uids, 64);
	ret = 1;
	while (mailbox_search_next(search_ctx, &mail) && ret > 0) {
		if (mail->expunged) {
			ret = 0;
			break;
		}

		if ((++copy_ctx->copy_count % COPY_CHECK_INTERVAL) == 0) {
			/* If we're COPYing (not MOVEing), check if client has
			   already disconnected. If yes, abort the COPY to
			   avoid client duplicating the COPY again later.
			   We can detect this as long as the client doesn't
			   fill the input buffer full. */
			if (client_send_sendalive_if_needed(client) < 0 ||
			    (!copy_ctx->move &&
			     client_is_disconnected(client))) {
				/* Client disconnected. Use the same failure
				   code path as if some messages were
				   expunged. */
				ret = 0;
				break;
			}
		}

		save_ctx = mailbox_save_alloc(t);
		mailbox_save_copy_flags(save_ctx, mail);

		if (copy_ctx->move) {
			if (mailbox_move(&save_ctx, mail) < 0)
				ret = -1;
		} else {
			if (mailbox_copy(&save_ctx, mail) < 0)
				ret = -1;
		}
		if (ret < 0 && mail->expunged)
			ret = 0;

		if (ret > 0)
			seq_range_array_add(&src_uids, mail->uid);
	}

	if (ret < 0) {
		copy_ctx->error_string =
			mailbox_get_last_error(copy_ctx->destbox, &copy_ctx->mail_error);
	}
	if (mailbox_search_deinit(&search_ctx) < 0 && ret >= 0) {
		copy_ctx->error_string =
			mailbox_get_last_error(copy_ctx->srcbox, &copy_ctx->mail_error);
		ret = -1;
	}

	/* Do a final check before committing COPY to see if the client has
	   already disconnected. */
	if (!copy_ctx->move && client_is_disconnected(client))
		ret = 0;

	if (ret <= 0)
		mailbox_transaction_rollback(&t);
	else if (mailbox_transaction_commit_get_changes(&t, &changes) < 0) {
		if (mailbox_get_last_mail_error(copy_ctx->destbox) == MAIL_ERROR_EXPUNGED) {
			/* storage backend didn't notice the expunge until
			   at commit time. */
			ret = 0;
		} else {
			ret = -1;
			copy_ctx->error_string =
				mailbox_get_last_error(copy_ctx->destbox, &copy_ctx->mail_error);
		}
	} else {
		if (changes.no_read_perm)
			copy_ctx->hide_saved_uids = TRUE;

		if (seq_range_count(&changes.saved_uids) == 0) {
			/* storage doesn't support returning UIDs */
			copy_ctx->hide_saved_uids = TRUE;
		}

		if (copy_ctx->uid_validity == 0)
			copy_ctx->uid_validity = changes.uid_validity;
		else if (copy_ctx->uid_validity != changes.uid_validity) {
			/* UIDVALIDITY unexpectedly changed */
			copy_ctx->hide_saved_uids = TRUE;
		}
		seq_range_array_merge(&copy_ctx->src_uids, &src_uids);
		seq_range_array_merge(&copy_ctx->saved_uids, &changes.saved_uids);

		i_assert(copy_ctx->copy_count == seq_range_count(&copy_ctx->saved_uids) ||
			 copy_ctx->hide_saved_uids);
		copy_update_trashed(client, copy_ctx->destbox, copy_ctx->copy_count);
		pool_unref(&changes.pool);
	}

	if (!copy_ctx->move ||
	    copy_ctx->srcbox == copy_ctx->destbox) {
		/* copying or moving within the same mailbox
		   succeeded or failed */
		if (mailbox_transaction_commit(&src_trans) < 0 && ret >= 0) {
			copy_ctx->error_string =
				mailbox_get_last_error(copy_ctx->srcbox, &copy_ctx->mail_error);
			ret = -1;
		}
	} else if (ret <= 0) {
		/* move failed, don't expunge anything */
		mailbox_transaction_rollback(&src_trans);
	} else {
		/* move succeeded */
		if (mailbox_transaction_commit(&src_trans) < 0 ||
		    mailbox_sync(copy_ctx->srcbox,
				 MAILBOX_SYNC_FLAG_EXPUNGE) < 0) {
			copy_ctx->error_string =
				mailbox_get_last_error(copy_ctx->srcbox, &copy_ctx->mail_error);
			ret = -1;
		}
	}
	return ret;
}

static void cmd_move_send_untagged(struct cmd_copy_context *copy_ctx,
				   string_t *msg, string_t *src_uidset)
{
	if (array_count(&copy_ctx->saved_uids) == 0)
		return;
	str_printfa(msg, "* OK [COPYUID %u %s ",
		    copy_ctx->uid_validity, str_c(src_uidset));
	imap_write_seq_range(msg, &copy_ctx->saved_uids);
	str_append(msg, "] Moved UIDs.");
	client_send_line(copy_ctx->cmd->client, str_c(msg));
}

static bool cmd_copy_full(struct client_command_context *cmd, bool move)
{
	struct client *client = cmd->client;
	struct mailbox *destbox;
        struct mail_search_args *search_args;
	struct imap_search_seqset_iter *seqset_iter = NULL;
	const char *messageset, *mailbox;
	enum mailbox_sync_flags sync_flags = 0;
	enum imap_sync_flags imap_flags = 0;
	struct cmd_copy_context copy_ctx;
	string_t *msg, *src_uidset;
	int ret;

	/* <message set> <mailbox> */
	if (!client_read_string_args(cmd, 2, &messageset, &mailbox))
		return FALSE;

	if (!client_verify_open_mailbox(cmd))
		return TRUE;

	/* First convert the message set to sequences. This way nonexistent
	   UIDs are dropped. */
	ret = imap_search_get_seqset(cmd, messageset, cmd->uid, &search_args);
	if (ret <= 0)
		return ret < 0;
	if (search_args->args->type == SEARCH_ALL) {
		i_assert(search_args->args->match_not);
		mail_search_args_unref(&search_args);
		return cmd_sync(cmd, sync_flags, imap_flags,
				"OK No messages found.");
	}
	/* Convert seqset to uidset. This is required for MOVE to work
	   correctly, since it opens another view for the source mailbox
	   that can have different sequences. */
	imap_search_anyset_to_uidset(cmd, search_args);

	if (client_open_save_dest_box(cmd, mailbox, &destbox) < 0) {
		mail_search_args_unref(&search_args);
		return TRUE;
	}

	i_zero(&copy_ctx);
	copy_ctx.cmd = cmd;
	copy_ctx.destbox = destbox;
	if (destbox == client->mailbox || !move)
		copy_ctx.srcbox = client->mailbox;
	else {
		copy_ctx.srcbox = mailbox_alloc(mailbox_get_namespace(client->mailbox)->list,
						mailbox_get_vname(client->mailbox), 0);
		if (mailbox_sync(copy_ctx.srcbox, 0) < 0) {
			mail_search_args_unref(&search_args);
			client_send_box_error(cmd, copy_ctx.srcbox);
			mailbox_free(&copy_ctx.srcbox);
			mailbox_free(&destbox);
			return TRUE;
		}
	}
	copy_ctx.move = move;
	i_array_init(&copy_ctx.src_uids, 8);
	i_array_init(&copy_ctx.saved_uids, 8);

	if (move) {
		/* When moving mails, perform the work in batches of
		   MOVE_COMMIT_INTERVAL. Each such batch has its own
		   transaction and search query. */
		seqset_iter = imap_search_seqset_iter_init(search_args,
			client->messages_count, MOVE_COMMIT_INTERVAL);
	}
	do {
		T_BEGIN {
			ret = fetch_and_copy(&copy_ctx, search_args);
		} T_END;
		if (ret <= 0) {
			/* failed */
			break;
		}
	} while (seqset_iter != NULL &&
		 imap_search_seqset_iter_next(seqset_iter));
	imap_search_seqset_iter_deinit(&seqset_iter);
	mail_search_args_unref(&search_args);

	src_uidset = t_str_new(256);
	imap_write_seq_range(src_uidset, &copy_ctx.src_uids);

	msg = t_str_new(256);
	if (ret <= 0) {
		if (move && array_count(&copy_ctx.src_uids) > 0) {
			/* some of the messages were successfully moved */
			cmd_move_send_untagged(&copy_ctx, msg, src_uidset);
		}
	} else if (copy_ctx.copy_count == 0) {
		str_append(msg, "OK No messages found.");
	} else if (seq_range_count(&copy_ctx.saved_uids) == 0 ||
		   copy_ctx.hide_saved_uids) {
		/* not supported by backend (virtual) or no read permissions
		   for mailbox */
		str_append(msg, move ? "OK Move completed." :
			   "OK Copy completed.");
	} else if (move) {
		cmd_move_send_untagged(&copy_ctx, msg, src_uidset);
		str_truncate(msg, 0);
		str_append(msg, "OK Move completed.");
	} else {
		str_printfa(msg, "OK [COPYUID %u %s ", copy_ctx.uid_validity,
			    str_c(src_uidset));
		imap_write_seq_range(msg, &copy_ctx.saved_uids);
		str_append(msg, "] Copy completed.");
	}

	array_free(&copy_ctx.src_uids);
	array_free(&copy_ctx.saved_uids);

	if (destbox != client->mailbox) {
		if (move)
			sync_flags |= MAILBOX_SYNC_FLAG_EXPUNGE;
		else
			sync_flags |= MAILBOX_SYNC_FLAG_FAST;
		imap_flags |= IMAP_SYNC_FLAG_SAFE;
		mailbox_free(&destbox);
	} else if (move) {
		sync_flags |= MAILBOX_SYNC_FLAG_EXPUNGE;
		imap_flags |= IMAP_SYNC_FLAG_SAFE;
	}
	if (copy_ctx.srcbox != client->mailbox)
		mailbox_free(&copy_ctx.srcbox);

	if (ret > 0)
		return cmd_sync(cmd, sync_flags, imap_flags, str_c(msg));
	else if (ret == 0) {
		/* some messages were expunged, sync them */
		return cmd_sync(cmd, 0, 0,
			"NO ["IMAP_RESP_CODE_EXPUNGEISSUED"] "
			"Some of the requested messages no longer exist.");
	} else {
		client_send_error(cmd, copy_ctx.error_string,
				  copy_ctx.mail_error);
		return TRUE;
	}
}

bool cmd_copy(struct client_command_context *cmd)
{
	return cmd_copy_full(cmd, FALSE);
}

bool cmd_move(struct client_command_context *cmd)
{
	return cmd_copy_full(cmd, TRUE);
}