/* Copyright (c) 2003-2009 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "array.h"
#include "mail-index-private.h"
#include "mail-index-modseq.h"
#include "mail-index-transaction-private.h"

static void
ext_reset_update_atomic(struct mail_index_transaction *t,
			uint32_t ext_id, uint32_t expected_reset_id)
{
	const struct mail_index_ext *map_ext;
	struct mail_transaction_ext_reset *reset;
	uint32_t idx, reset_id;

	if (!mail_index_map_get_ext_idx(t->view->index->map, ext_id, &idx)) {
		/* new extension */
		reset_id = 1;
	} else {
		map_ext = array_idx(&t->view->index->map->extensions, idx);
		reset_id = map_ext->reset_id + 1;
	}
	if (reset_id != expected_reset_id) {
		/* ignore this extension update */
		mail_index_ext_set_reset_id(t, ext_id, 0);
		return;
	}

	if (reset_id == 0)
		reset_id++;

	array_idx_set(&t->ext_reset_ids, ext_id, &reset_id);

	/* reseting existing data is optional */
	if (array_is_created(&t->ext_resets)) {
		reset = array_idx_modifiable(&t->ext_resets, ext_id);
		if (reset->new_reset_id == (uint32_t)-1)
			reset->new_reset_id = reset_id;
	}
}

static void
transaction_update_atomic_reset_ids(struct mail_index_transaction *t)
{
	const uint32_t *expected_reset_ids;
	unsigned int ext_id, count;

	if (!array_is_created(&t->ext_reset_atomic))
		return;

	expected_reset_ids = array_get(&t->ext_reset_atomic, &count);
	for (ext_id = 0; ext_id < count; ext_id++) {
		if (expected_reset_ids[ext_id] != 0) {
			ext_reset_update_atomic(t, ext_id,
						expected_reset_ids[ext_id]);
		}
	}
}

static unsigned int
mail_transaction_drop_range(struct mail_index_transaction *t,
			    struct mail_transaction_flag_update update,
			    unsigned int update_idx,
			    ARRAY_TYPE(seq_range) *keeps)
{
	const struct seq_range *keep_range;
	unsigned int i, keep_count;

	keep_range = array_get(keeps, &keep_count);
	if (keep_count == 1 &&
	    update.uid1 == keep_range[0].seq1 &&
	    update.uid2 == keep_range[0].seq2) {
		/* evereything is kept */
		return update_idx + 1;
	}

	array_delete(&t->updates, update_idx, 1);

	/* add back all the updates we want to keep */
	for (i = 0; i < keep_count; i++, update_idx++) {
		update.uid1 = keep_range[i].seq1;
		update.uid2 = keep_range[i].seq2;
		array_insert(&t->updates, update_idx, &update, 1);
	}
	return update_idx;
}

static void
mail_index_transaction_finish_flag_updates(struct mail_index_transaction *t)
{
	const struct mail_transaction_flag_update *updates, *u;
	const struct mail_index_record *rec;
	unsigned int i, count;
	ARRAY_TYPE(seq_range) keeps;
	uint32_t seq;

	if (!t->drop_unnecessary_flag_updates)
		return;

	t_array_init(&keeps, 64);
	updates = array_get(&t->updates, &count);
	for (i = 0; i < count; ) {
		/* first get the list of changes to drop */
		u = &updates[i];
		array_clear(&keeps);
		for (seq = u->uid1; seq <= u->uid2; seq++) {
			rec = mail_index_lookup(t->view, seq);
			if ((rec->flags & u->add_flags) != u->add_flags ||
			    (rec->flags & u->remove_flags) != 0) {
				/* keep this change */
				seq_range_array_add(&keeps, 0, seq);
			}
		}
		i = mail_transaction_drop_range(t, updates[i], i, &keeps);
	}

	if (array_count(&t->updates) == 0)
		array_free(&t->updates);
}

static bool
mail_index_update_cancel_array(ARRAY_TYPE(seq_range) *array, uint32_t seq)
{
	if (array_is_created(array)) {
		if (seq_range_array_remove(array, seq)) {
			if (array_count(array) == 0)
				array_free(array);
			return TRUE;
		}
	}
	return FALSE;
}

static bool
mail_index_update_cancel(struct mail_index_transaction *t, uint32_t seq)
{
	struct mail_index_transaction_keyword_update *kw;
	struct mail_transaction_flag_update *updates, tmp_update;
	unsigned int i, count;
	bool ret, have_kw_changes = FALSE;

	ret = mail_index_update_cancel_array(&t->keyword_resets, seq);
	if (array_is_created(&t->keyword_updates)) {
		kw = array_get_modifiable(&t->keyword_updates, &count);
		for (i = 0; i < count; i++) {
			if (mail_index_update_cancel_array(&kw[i].add_seq, seq))
				ret = TRUE;
			if (mail_index_update_cancel_array(&kw[i].remove_seq,
							   seq))
				ret = TRUE;
			if (array_is_created(&kw[i].add_seq) ||
			    array_is_created(&kw[i].remove_seq))
				have_kw_changes = TRUE;
		}
		if (!have_kw_changes)
			array_free(&t->keyword_updates);
	}

	if (!array_is_created(&t->updates))
		return ret;

	updates = array_get_modifiable(&t->updates, &count);
	i = mail_index_transaction_get_flag_update_pos(t, 0, count, seq);
	if (i < count && updates[i].uid1 <= seq && updates[i].uid2 >= seq) {
		/* exists */
		ret = TRUE;
		if (updates[i].uid1 == seq && updates[i].uid2 == seq) {
			if (count > 1)
				array_delete(&t->updates, i, 1);
			else
				array_free(&t->updates);
		} else if (updates[i].uid1 == seq)
			updates[i].uid1++;
		else if (updates[i].uid2 == seq)
			updates[i].uid2--;
		else {
			/* need to split it in two */
			tmp_update = updates[i];
			tmp_update.uid1 = seq+1;
			updates[i].uid2 = seq-1;
			array_insert(&t->updates, i + 1, &tmp_update, 1);
		}
	}
	return ret;
}

static void
mail_index_transaction_check_conflicts(struct mail_index_transaction *t)
{
	uint32_t seq;

	i_assert(t->max_modseq != 0);
	i_assert(t->conflict_seqs != NULL);

	if (t->max_modseq == mail_index_modseq_get_highest(t->view)) {
		/* no conflicts possible */
		return;
	}
	if (t->min_flagupdate_seq == 0) {
		/* no flag updates */
		return;
	}

	for (seq = t->min_flagupdate_seq; seq <= t->max_flagupdate_seq; seq++) {
		if (mail_index_modseq_lookup(t->view, seq) > t->max_modseq) {
			if (mail_index_update_cancel(t, seq))
				seq_range_array_add(t->conflict_seqs, 0, seq);
		}
	}
	mail_index_transaction_set_log_updates(t);
}

static uint32_t
mail_index_transaction_get_uid(struct mail_index_transaction *t, uint32_t seq)
{
	const struct mail_index_record *rec;

	i_assert(seq > 0);

	if (seq >= t->first_new_seq)
		rec = mail_index_transaction_lookup(t, seq);
	else {
		i_assert(seq <= t->view->map->hdr.messages_count);
		rec = MAIL_INDEX_MAP_IDX(t->view->map, seq - 1);
	}
	i_assert(rec->uid != 0);
	return rec->uid;
}

static void
mail_index_convert_to_uids(struct mail_index_transaction *t,
			   ARRAY_TYPE(seq_array) *array)
{
	uint32_t *seq;
	unsigned int i, count;

	if (!array_is_created(array))
		return;

	count = array_count(array);
	for (i = 0; i < count; i++) {
		seq = array_idx_modifiable(array, i);
		*seq = mail_index_transaction_get_uid(t, *seq);
	}
}

static uint32_t
get_nonexpunged_uid2(struct mail_index_transaction *t,
		     uint32_t uid1, uint32_t seq1)
{
	seq1++;

	while (mail_index_transaction_get_uid(t, seq1) == uid1 + 1) {
		seq1++;
		uid1++;
	}
	return uid1;
}

static void
mail_index_convert_to_uid_ranges(struct mail_index_transaction *t,
				 ARRAY_TYPE(seq_range) *array)
{
	struct seq_range *range, *new_range;
	unsigned int i, count;
	uint32_t uid1, uid2;

	if (!array_is_created(array))
		return;

	count = array_count(array);
	for (i = 0; i < count; i++) {
		range = array_idx_modifiable(array, i);

		uid1 = mail_index_transaction_get_uid(t, range->seq1);
		uid2 = mail_index_transaction_get_uid(t, range->seq2);
		if (uid2 - uid1 == range->seq2 - range->seq1) {
			/* simple conversion */
			range->seq1 = uid1;
			range->seq2 = uid2;
		} else {
			/* remove expunged UIDs */
			new_range = array_insert_space(array, i);
			range = array_idx_modifiable(array, i + 1);
			count++;

			memcpy(new_range, range, array->arr.element_size);
			new_range->seq1 = uid1;
			new_range->seq2 = get_nonexpunged_uid2(t, uid1,
							       range->seq1);

			/* continue the range without the inserted seqs */
			range->seq1 += new_range->seq2 - new_range->seq1 + 1;
		}
	}
}

static void keyword_updates_convert_to_uids(struct mail_index_transaction *t)
{
        struct mail_index_transaction_keyword_update *updates;
	unsigned int i, count;

	if (!array_is_created(&t->keyword_updates))
		return;

	updates = array_get_modifiable(&t->keyword_updates, &count);
	for (i = 0; i < count; i++) {
		mail_index_convert_to_uid_ranges(t, &updates[i].add_seq);
		mail_index_convert_to_uid_ranges(t, &updates[i].remove_seq);
	}
}

static void
mail_index_transaction_convert_to_uids(struct mail_index_transaction *t)
{
	ARRAY_TYPE(seq_array) *updates;
	unsigned int i, count;

	if (array_is_created(&t->ext_rec_updates)) {
		updates = array_get_modifiable(&t->ext_rec_updates, &count);
		for (i = 0; i < count; i++)
			mail_index_convert_to_uids(t, (void *)&updates[i]);
	}
	if (array_is_created(&t->ext_rec_atomics)) {
		updates = array_get_modifiable(&t->ext_rec_atomics, &count);
		for (i = 0; i < count; i++)
			mail_index_convert_to_uids(t, (void *)&updates[i]);
	}

        keyword_updates_convert_to_uids(t);

	mail_index_convert_to_uid_ranges(t, &t->expunges);
	mail_index_convert_to_uid_ranges(t, (void *)&t->updates);
	mail_index_convert_to_uid_ranges(t, &t->keyword_resets);
}

int mail_index_transaction_finish(struct mail_index_transaction *t)
{
	mail_index_transaction_sort_appends(t);
	mail_index_transaction_finish_flag_updates(t);

	if (array_is_created(&t->ext_reset_atomic) || t->max_modseq != 0) {
		if (mail_index_map(t->view->index,
				   MAIL_INDEX_SYNC_HANDLER_HEAD) <= 0)
			return -1;
	}
	if (array_is_created(&t->ext_reset_atomic))
		transaction_update_atomic_reset_ids(t);
	if (t->max_modseq != 0)
		mail_index_transaction_check_conflicts(t);
	/* finally convert all sequences to UIDs before we write them,
	   but after we've checked and removed conflicts */
	mail_index_transaction_convert_to_uids(t);
	return 0;
}