/* Copyright (c) 2002-2008 Dovecot authors, see the included COPYING file */

#include "common.h"

#include "str.h"

#include "ostream.h"

#include "mail-storage.h"

#include "imap-util.h"

#include "imap-sync.h"

#include "commands.h"

struct client_sync_context {

	/* if multiple commands are in progress, we may need to wait for them

	   to finish before syncing mailbox. */

	unsigned int counter;

	enum mailbox_sync_flags flags;

	enum imap_sync_flags imap_flags;

	const char *tagline;

	imap_sync_callback_t *callback;

};

struct imap_sync_context {

	struct client *client;

	struct mailbox *box;

        enum imap_sync_flags imap_flags;

	struct mailbox_transaction_context *t;

	struct mailbox_sync_context *sync_ctx;

	struct mail *mail;

	struct mailbox_sync_rec sync_rec;

	ARRAY_TYPE(keywords) tmp_keywords;

	uint32_t seq;

	unsigned int messages_count;

	unsigned int failed:1;

	unsigned int no_newmail:1;

};

struct imap_sync_context *

imap_sync_init(struct client *client, struct mailbox *box,

	       enum imap_sync_flags imap_flags, enum mailbox_sync_flags flags)

{

	struct imap_sync_context *ctx;

	i_assert(client->mailbox == box);

	ctx = i_new(struct imap_sync_context, 1);

	ctx->client = client;

	ctx->box = box;

	ctx->imap_flags = imap_flags;

	ctx->sync_ctx = mailbox_sync_init(box, flags);

	ctx->t = mailbox_transaction_begin(box, 0);

	ctx->mail = mail_alloc(ctx->t, MAIL_FETCH_FLAGS, 0);

	ctx->messages_count = client->messages_count;

	i_array_init(&ctx->tmp_keywords, client->keywords.announce_count + 8);

	client_send_mailbox_flags(client, FALSE);

	return ctx;

}

int imap_sync_deinit(struct imap_sync_context *ctx)

{

	struct mailbox_status status;

	int ret;

	mail_free(&ctx->mail);

	if (mailbox_sync_deinit(&ctx->sync_ctx, STATUS_UIDVALIDITY |

				STATUS_MESSAGES | STATUS_RECENT, &status) < 0 ||

	    ctx->failed) {

		mailbox_transaction_rollback(&ctx->t);

		i_free(ctx);

		return -1;

	}

	ret = mailbox_transaction_commit(&ctx->t);

	if (status.uidvalidity != ctx->client->uidvalidity) {

		/* most clients would get confused by this. disconnect them. */

		client_disconnect_with_error(ctx->client,

					     "Mailbox UIDVALIDITY changed");

	}

	if (!ctx->no_newmail) {

		if (status.messages < ctx->messages_count)

			i_panic("Message count decreased");

		ctx->client->messages_count = status.messages;

		if (status.messages != ctx->messages_count) {

			client_send_line(ctx->client,

				t_strdup_printf("* %u EXISTS", status.messages));

		}

		if (status.recent != ctx->client->recent_count &&

		    !ctx->no_newmail) {

			ctx->client->recent_count = status.recent;

			client_send_line(ctx->client,

				t_strdup_printf("* %u RECENT", status.recent));

		}

	}

	array_free(&ctx->tmp_keywords);

	i_free(ctx);

	return ret;

}

static int imap_sync_send_flags(struct imap_sync_context *ctx, string_t *str)

{

	enum mail_flags flags;

	const char *const *keywords;

	mail_set_seq(ctx->mail, ctx->seq);

	flags = mail_get_flags(ctx->mail);

	keywords = client_get_keyword_names(ctx->client, &ctx->tmp_keywords,

			mail_get_keyword_indexes(ctx->mail));

	if ((flags & MAIL_DELETED) != 0)

		ctx->client->sync_seen_deletes = TRUE;

	str_truncate(str, 0);

	str_printfa(str, "* %u FETCH (", ctx->seq);

	if (ctx->imap_flags & IMAP_SYNC_FLAG_SEND_UID)

		str_printfa(str, "UID %u ", ctx->mail->uid);

	str_append(str, "FLAGS (");

	imap_write_flags(str, flags, keywords);

	str_append(str, "))");

	return client_send_line(ctx->client, str_c(str));

}

int imap_sync_more(struct imap_sync_context *ctx)

{

	string_t *str;

	int ret = 1;

	str = t_str_new(256);

	for (;;) {

		if (ctx->seq == 0) {

			/* get next one */

			if (!mailbox_sync_next(ctx->sync_ctx, &ctx->sync_rec)) {

				/* finished */

				ret = 1;

				break;

			}

		}

		if (ctx->sync_rec.seq2 > ctx->messages_count) {

			/* don't send change notifications of messages we

			   haven't even announced to client yet */

			if (ctx->sync_rec.seq1 > ctx->messages_count) {

				ctx->seq = 0;

				continue;

			}

			ctx->sync_rec.seq2 = ctx->messages_count;

		}

		switch (ctx->sync_rec.type) {

		case MAILBOX_SYNC_TYPE_FLAGS:

			if (ctx->seq == 0)

				ctx->seq = ctx->sync_rec.seq1;

			ret = 1;

			for (; ctx->seq <= ctx->sync_rec.seq2; ctx->seq++) {

				if (ret <= 0)

					break;

				ret = imap_sync_send_flags(ctx, str);

			}

			break;

		case MAILBOX_SYNC_TYPE_EXPUNGE:

			if (ctx->seq == 0)

				ctx->seq = ctx->sync_rec.seq2;

			ret = 1;

			for (; ctx->seq >= ctx->sync_rec.seq1; ctx->seq--) {

				if (ret <= 0)

					break;

				str_truncate(str, 0);

				str_printfa(str, "* %u EXPUNGE", ctx->seq);

				ret = client_send_line(ctx->client, str_c(str));

			}

			if (ctx->seq < ctx->sync_rec.seq1) {

				/* update only after we're finished, so that

				   the seq2 > messages_count check above

				   doesn't break */

				ctx->messages_count -=

					ctx->sync_rec.seq2 -

					ctx->sync_rec.seq1 + 1;

			}

			break;

		}

		if (ret <= 0) {

			/* failure / buffer full */

			break;

		}

		ctx->seq = 0;

	}

	return ret;

}

static bool cmd_finish_sync(struct client_command_context *cmd)

{

	if (cmd->sync->callback != NULL)

		return cmd->sync->callback(cmd);

	else {

		client_send_tagline(cmd, cmd->sync->tagline);

		return TRUE;

	}

}

static bool cmd_sync_continue(struct client_command_context *sync_cmd)

{

	struct client_command_context *cmd, *prev;

	struct client *client = sync_cmd->client;

	struct imap_sync_context *ctx = sync_cmd->context;

	int ret;

	i_assert(ctx->client == client);

	if ((ret = imap_sync_more(ctx)) == 0)

		return FALSE;

	if (ret < 0)

		ctx->failed = TRUE;

	client->syncing = FALSE;

	if (imap_sync_deinit(ctx) < 0) {

		client_send_untagged_storage_error(client,

			mailbox_get_storage(client->mailbox));

	}

	sync_cmd->context = NULL;

	/* Finish all commands that waited for this sync. Go through the queue

	   backwards, so that tagged replies are sent in the same order as

	   they were received. This fixes problems with clients that rely on

	   this (Apple Mail 3.2) */

	for (cmd = client->command_queue; cmd->next != NULL; cmd = cmd->next) ;

	for (; cmd != NULL; cmd = prev) {

		prev = cmd->prev;

		if (cmd->state == CLIENT_COMMAND_STATE_WAIT_SYNC &&

		    cmd != sync_cmd &&

		    cmd->sync->counter+1 == client->sync_counter) {

			if (cmd_finish_sync(cmd))

				client_command_free(&cmd);

		}

	}

	return cmd_finish_sync(sync_cmd);

}

static void get_common_sync_flags(struct client *client,

				  enum mailbox_sync_flags *flags_r,

				  enum imap_sync_flags *imap_flags_r)

{

	struct client_command_context *cmd;

	unsigned int count = 0, fast_count = 0, noexpunges_count = 0;

	*flags_r = 0;

	*imap_flags_r = 0;

	for (cmd = client->command_queue; cmd != NULL; cmd = cmd->next) {

		if (cmd->sync != NULL &&

		    cmd->sync->counter == client->sync_counter) {

			if ((cmd->sync->flags & MAILBOX_SYNC_FLAG_FAST) != 0)

				fast_count++;

			if (cmd->sync->flags & MAILBOX_SYNC_FLAG_NO_EXPUNGES)

				noexpunges_count++;

			*flags_r |= cmd->sync->flags;

			*imap_flags_r |= cmd->sync->imap_flags;

			count++;

		}

	}

	i_assert(noexpunges_count == 0 || noexpunges_count == count);

	if (fast_count != count)

		*flags_r &= ~MAILBOX_SYNC_FLAG_FAST;

	i_assert((*flags_r & (MAILBOX_SYNC_AUTO_STOP |

			      MAILBOX_SYNC_FLAG_FIX_INCONSISTENT)) == 0);

}

static bool cmd_sync_client(struct client_command_context *sync_cmd)

{

	struct client *client = sync_cmd->client;

	struct imap_sync_context *ctx;

	enum mailbox_sync_flags flags;

	enum imap_sync_flags imap_flags;

	bool no_newmail;

	/* there may be multiple commands waiting. use their combined flags */

	get_common_sync_flags(client, &flags, &imap_flags);

	client->sync_counter++;

	no_newmail = (client_workarounds & WORKAROUND_DELAY_NEWMAIL) != 0 &&

		(imap_flags & IMAP_SYNC_FLAG_SAFE) == 0;

	if (no_newmail) {

		/* expunges might break the client just as badly as new mail

		   notifications. */

		flags |= MAILBOX_SYNC_FLAG_NO_EXPUNGES;

	}

	client->syncing = TRUE;

	ctx = imap_sync_init(client, client->mailbox, imap_flags, flags);

	ctx->no_newmail = no_newmail;

	/* handle the syncing using sync_cmd. it doesn't actually matter which

	   one of the pending commands it is. */

	sync_cmd->func = cmd_sync_continue;

	sync_cmd->context = ctx;

	sync_cmd->state = CLIENT_COMMAND_STATE_WAIT_OUTPUT;

	if (!cmd_sync_continue(sync_cmd)) {

		o_stream_set_flush_pending(client->output, TRUE);

		return FALSE;

	}

	client_command_free(&sync_cmd);

	(void)cmd_sync_delayed(client);

	return TRUE;

}

static bool

cmd_sync_full(struct client_command_context *cmd, enum mailbox_sync_flags flags,

	      enum imap_sync_flags imap_flags, const char *tagline,

	      imap_sync_callback_t *callback)

{

	struct client *client = cmd->client;

	i_assert(client->output_lock == cmd || client->output_lock == NULL);

	if (cmd->cancel)

		return TRUE;

	if (client->mailbox == NULL) {

		/* no mailbox selected, no point in delaying the sync */

		i_assert(callback == NULL);

		client_send_tagline(cmd, tagline);

		return TRUE;

	}

	cmd->sync = p_new(cmd->pool, struct client_sync_context, 1);

	cmd->sync->counter = client->sync_counter;

	cmd->sync->flags = flags;

	cmd->sync->imap_flags = imap_flags;

	cmd->sync->tagline = p_strdup(cmd->pool, tagline);

	cmd->sync->callback = callback;

	cmd->state = CLIENT_COMMAND_STATE_WAIT_SYNC;

	cmd->func = NULL;

	cmd->context = NULL;

	client->output_lock = NULL;

	if (client->input_lock == cmd)

		client->input_lock = NULL;

	return FALSE;

}

bool cmd_sync(struct client_command_context *cmd, enum mailbox_sync_flags flags,

	      enum imap_sync_flags imap_flags, const char *tagline)

{

	return cmd_sync_full(cmd, flags, imap_flags, tagline, NULL);

}

bool cmd_sync_callback(struct client_command_context *cmd,

		       enum mailbox_sync_flags flags,

		       enum imap_sync_flags imap_flags,

		       imap_sync_callback_t *callback)

{

	return cmd_sync_full(cmd, flags, imap_flags, NULL, callback);

}

static bool cmd_sync_drop_fast(struct client *client)

{

	struct client_command_context *cmd, *prev;

	bool ret = FALSE;

	if (client->command_queue == NULL)

		return FALSE;

	for (cmd = client->command_queue; cmd->next != NULL; cmd = cmd->next) ;

	for (; cmd != NULL; cmd = prev) {

		prev = cmd->next;

		if (cmd->state == CLIENT_COMMAND_STATE_WAIT_SYNC &&

		    (cmd->sync->flags & MAILBOX_SYNC_FLAG_FAST) != 0) {

			if (cmd_finish_sync(cmd)) {

				client_command_free(&cmd);

				ret = TRUE;

			}

		}

	}

	return ret;

}

bool cmd_sync_delayed(struct client *client)

{

	struct client_command_context *cmd, *first_expunge, *first_nonexpunge;

	if (client->output_lock != NULL) {

		/* wait until we can send output to client */

		return FALSE;

	}

	if (client->syncing ||

	    (client->mailbox != NULL &&

	     mailbox_transaction_get_count(client->mailbox) > 0)) {

		/* wait until mailbox can be synced */

		return cmd_sync_drop_fast(client);

	}

	/* separate syncs that can send expunges from those that can't */

	first_expunge = first_nonexpunge = NULL;

	for (cmd = client->command_queue; cmd != NULL; cmd = cmd->next) {

		if (cmd->sync != NULL &&

		    cmd->sync->counter == client->sync_counter) {

			if (cmd->sync->flags & MAILBOX_SYNC_FLAG_NO_EXPUNGES) {

				if (first_nonexpunge == NULL)

					first_nonexpunge = cmd;

			} else {

				if (first_expunge == NULL)

					first_expunge = cmd;

			}

		}

	}

	if (first_expunge != NULL && first_nonexpunge != NULL) {

		/* sync expunges after nonexpunges */

		for (cmd = first_expunge; cmd != NULL; cmd = cmd->next) {

			if (cmd->sync != NULL &&

			    cmd->sync->counter == client->sync_counter &&

			    (cmd->sync->flags &

			     MAILBOX_SYNC_FLAG_NO_EXPUNGES) == 0)

				cmd->sync->counter++;

		}

		first_expunge = NULL;

	}

	cmd = first_nonexpunge != NULL ? first_nonexpunge : first_expunge;

	if (cmd == NULL)

		return cmd_sync_drop_fast(client);

	i_assert(client->mailbox != NULL);

	return cmd_sync_client(cmd);

}