/* Copyright (c) 2003-2018 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-transaction-log-private.h"
#include "mail-index-transaction-private.h"

struct mail_index_export_context {
	struct mail_index_transaction *trans;
	struct mail_transaction_log_append_ctx *append_ctx;
};

static void
log_append_buffer(struct mail_index_export_context *ctx,
		  const buffer_t *buf, enum mail_transaction_type type)
{
	mail_transaction_log_append_add(ctx->append_ctx, type,
					buf->data, buf->used);
}

static void log_append_flag_updates(struct mail_index_export_context *ctx,
				    struct mail_index_transaction *t)
{
	ARRAY(struct mail_transaction_flag_update) log_updates;
	const struct mail_index_flag_update *updates;
	struct mail_transaction_flag_update *log_update;
	unsigned int i, count;

	updates = array_get(&t->updates, &count);
	if (count == 0)
		return;

	i_array_init(&log_updates, count);

	for (i = 0; i < count; i++) {
		log_update = array_append_space(&log_updates);
		log_update->uid1 = updates[i].uid1;
		log_update->uid2 = updates[i].uid2;
		log_update->add_flags = updates[i].add_flags & 0xff;
		log_update->remove_flags = updates[i].remove_flags & 0xff;
		if ((updates[i].add_flags & MAIL_INDEX_MAIL_FLAG_UPDATE_MODSEQ) != 0)
			log_update->modseq_inc_flag = 1;
	}
	log_append_buffer(ctx, log_updates.arr.buffer,
			  MAIL_TRANSACTION_FLAG_UPDATE);
	array_free(&log_updates);
}

static const buffer_t *
log_get_hdr_update_buffer(struct mail_index_transaction *t, bool prepend)
{
	buffer_t *buf;
	const unsigned char *data, *mask;
	struct mail_transaction_header_update u;
	uint16_t offset;
	int state = 0;

	i_zero(&u);

	data = prepend ? t->pre_hdr_change : t->post_hdr_change;
	mask = prepend ? t->pre_hdr_mask : t->post_hdr_mask;

	buf = t_buffer_create(256);
	for (offset = 0; offset <= sizeof(t->pre_hdr_change); offset++) {
		if (offset < sizeof(t->pre_hdr_change) && mask[offset] != 0) {
			if (state == 0) {
				u.offset = offset;
				state++;
			}
		} else {
			if (state > 0) {
				u.size = offset - u.offset;
				buffer_append(buf, &u, sizeof(u));
				buffer_append(buf, data + u.offset, u.size);
				state = 0;
			}
		}
	}
	return buf;
}

static unsigned int
ext_hdr_update_get_size(const struct mail_index_transaction_ext_hdr_update *hu)
{
	unsigned int i;

	for (i = hu->alloc_size; i > 0; i--) {
		if (hu->mask[i-1] != 0)
			return i;
	}
	return 0;
}

static void log_append_ext_intro(struct mail_index_export_context *ctx,
				 uint32_t ext_id, uint32_t reset_id,
				 unsigned int *hdr_size_r)
{
	struct mail_index_transaction *t = ctx->trans;
	const struct mail_index_registered_ext *rext;
	const struct mail_index_ext *ext;
        struct mail_transaction_ext_intro *intro, *resizes;
	buffer_t *buf;
	uint32_t idx;
	unsigned int count;

	i_assert(ext_id != (uint32_t)-1);

	if (t->reset ||
	    !mail_index_map_get_ext_idx(t->view->index->map, ext_id, &idx)) {
		/* new extension */
		idx = (uint32_t)-1;
	}

	rext = array_idx(&t->view->index->extensions, ext_id);
	if (!array_is_created(&t->ext_resizes)) {
		resizes = NULL;
		count = 0;
	} else {
		resizes = array_get_modifiable(&t->ext_resizes, &count);
	}

	buf = t_buffer_create(128);
	if (ext_id < count && resizes[ext_id].name_size != 0) {
		/* we're resizing the extension. use the resize struct. */
		intro = &resizes[ext_id];

		if (idx != (uint32_t)-1) {
			intro->ext_id = idx;
			intro->name_size = 0;
		} else {
			intro->ext_id = (uint32_t)-1;
			intro->name_size = strlen(rext->name);
		}
		buffer_append(buf, intro, sizeof(*intro));
	} else {
		/* generate a new intro structure */
		intro = buffer_append_space_unsafe(buf, sizeof(*intro));
		intro->ext_id = idx;
		intro->record_size = rext->record_size;
		intro->record_align = rext->record_align;
		if (idx == (uint32_t)-1) {
			intro->hdr_size = rext->hdr_size;
			intro->name_size = strlen(rext->name);
		} else {
			ext = array_idx(&t->view->index->map->extensions, idx);
			intro->hdr_size = ext->hdr_size;
			intro->name_size = 0;
		}
		intro->flags = MAIL_TRANSACTION_EXT_INTRO_FLAG_NO_SHRINK;

		/* handle increasing header size automatically */
		if (array_is_created(&t->ext_hdr_updates) &&
		    ext_id < array_count(&t->ext_hdr_updates)) {
			const struct mail_index_transaction_ext_hdr_update *hu;
			unsigned int hdr_update_size;

			hu = array_idx(&t->ext_hdr_updates, ext_id);
			hdr_update_size = ext_hdr_update_get_size(hu);
			if (intro->hdr_size < hdr_update_size)
				intro->hdr_size = hdr_update_size;
		}
	}
	i_assert(intro->record_size != 0 || intro->hdr_size != 0);
	if (reset_id != 0) {
		/* we're going to reset this extension in this transaction */
		intro->reset_id = reset_id;
	} else if (idx != (uint32_t)-1) {
		/* use the existing reset_id */
		const struct mail_index_ext *map_ext =
			array_idx(&t->view->index->map->extensions, idx);
		intro->reset_id = map_ext->reset_id;
	} else {
		/* new extension, reset_id defaults to 0 */
	}
	buffer_append(buf, rext->name, intro->name_size);
	if ((buf->used % 4) != 0)
		buffer_append_zero(buf, 4 - (buf->used % 4));

	if (ctx->append_ctx->new_highest_modseq == 0 &&
	    strcmp(rext->name, MAIL_INDEX_MODSEQ_EXT_NAME) == 0) {
		/* modseq tracking started */
		ctx->append_ctx->new_highest_modseq = 1;
	}

	log_append_buffer(ctx, buf, MAIL_TRANSACTION_EXT_INTRO);
	*hdr_size_r = intro->hdr_size;
}

static void
log_append_ext_hdr_update(struct mail_index_export_context *ctx,
			  const struct mail_index_transaction_ext_hdr_update *hdr,
			  unsigned int ext_hdr_size)
{
	buffer_t *buf;
	const unsigned char *data, *mask;
	struct mail_transaction_ext_hdr_update u;
	struct mail_transaction_ext_hdr_update32 u32;
	size_t offset;
	bool started = FALSE, use_32 = hdr->alloc_size >= 65536;

	i_zero(&u);
	i_zero(&u32);

	data = hdr->data;
	mask = hdr->mask;

	buf = buffer_create_dynamic(default_pool, 256);
	for (offset = 0; offset <= hdr->alloc_size; offset++) {
		if (offset < hdr->alloc_size && mask[offset] != 0) {
			if (!started) {
				u32.offset = offset;
				started = TRUE;
			}
		} else {
			if (started) {
				u32.size = offset - u32.offset;
				if (use_32)
					buffer_append(buf, &u32, sizeof(u32));
				else {
					u.offset = u32.offset;
					u.size = u32.size;
					buffer_append(buf, &u, sizeof(u));
				}
				i_assert(u32.offset + u32.size <= ext_hdr_size);
				buffer_append(buf, data + u32.offset, u32.size);
				started = FALSE;
			}
		}
	}
	if (buf->used % 4 != 0)
		buffer_append_zero(buf, 4 - buf->used % 4);
	log_append_buffer(ctx, buf, use_32 ? MAIL_TRANSACTION_EXT_HDR_UPDATE32 :
			  MAIL_TRANSACTION_EXT_HDR_UPDATE);
	buffer_free(&buf);
}

static void
mail_transaction_log_append_ext_intros(struct mail_index_export_context *ctx)
{
	struct mail_index_transaction *t = ctx->trans;
        const struct mail_transaction_ext_intro *resize;
	const struct mail_index_transaction_ext_hdr_update *hdrs;
	struct mail_transaction_ext_reset ext_reset;
	unsigned int resize_count, ext_count = 0;
	unsigned int hdrs_count, reset_id_count, reset_count, hdr_size;
	uint32_t ext_id, reset_id;
	const struct mail_transaction_ext_reset *reset;
	const uint32_t *reset_ids;
	buffer_t reset_buf;

	if (!array_is_created(&t->ext_resizes)) {
		resize = NULL;
		resize_count = 0;
	} else {
		resize = array_get(&t->ext_resizes, &resize_count);
		if (ext_count < resize_count)
			ext_count = resize_count;
	}

	if (!array_is_created(&t->ext_reset_ids)) {
		reset_ids = NULL;
		reset_id_count = 0;
	} else {
		reset_ids = array_get(&t->ext_reset_ids, &reset_id_count);
	}

	if (!array_is_created(&t->ext_resets)) {
		reset = NULL;
		reset_count = 0;
	} else {
		reset = array_get(&t->ext_resets, &reset_count);
		if (ext_count < reset_count)
			ext_count = reset_count;
	}

	if (!array_is_created(&t->ext_hdr_updates)) {
		hdrs = NULL;
		hdrs_count = 0;
	} else {
		hdrs = array_get(&t->ext_hdr_updates, &hdrs_count);
		if (ext_count < hdrs_count)
			ext_count = hdrs_count;
	}

	i_zero(&ext_reset);
	buffer_create_from_data(&reset_buf, &ext_reset, sizeof(ext_reset));
	buffer_set_used_size(&reset_buf, sizeof(ext_reset));

	for (ext_id = 0; ext_id < ext_count; ext_id++) {
		if (ext_id < reset_count)
			ext_reset = reset[ext_id];
		else
			ext_reset.new_reset_id = 0;
		if ((ext_id < resize_count && resize[ext_id].name_size > 0) ||
		    ext_reset.new_reset_id != 0 ||
		    (ext_id < hdrs_count && hdrs[ext_id].alloc_size > 0)) {
			if (ext_reset.new_reset_id != 0) {
				/* we're going to reset this extension
				   immediately after the intro */
				reset_id = 0;
			} else {
				reset_id = ext_id < reset_id_count ?
					reset_ids[ext_id] : 0;
			}
			log_append_ext_intro(ctx, ext_id, reset_id, &hdr_size);
		} else {
			hdr_size = 0;
		}
		if (ext_reset.new_reset_id != 0) {
			i_assert(ext_id < reset_id_count &&
				 ext_reset.new_reset_id == reset_ids[ext_id]);
			log_append_buffer(ctx, &reset_buf,
					  MAIL_TRANSACTION_EXT_RESET);
		}
		if (ext_id < hdrs_count && hdrs[ext_id].alloc_size > 0) {
			T_BEGIN {
				log_append_ext_hdr_update(ctx, &hdrs[ext_id],
							  hdr_size);
			} T_END;
		}
	}
}

static void log_append_ext_recs(struct mail_index_export_context *ctx,
				const ARRAY_TYPE(seq_array_array) *arr,
				enum mail_transaction_type type)
{
	struct mail_index_transaction *t = ctx->trans;
	const ARRAY_TYPE(seq_array) *updates;
	const uint32_t *reset_ids;
	unsigned int ext_id, count, reset_id_count, hdr_size;
	uint32_t reset_id;

	if (!array_is_created(&t->ext_reset_ids)) {
		reset_ids = NULL;
		reset_id_count = 0;
	} else {
		reset_ids = array_get_modifiable(&t->ext_reset_ids,
						 &reset_id_count);
	}

	updates = array_get(arr, &count);
	for (ext_id = 0; ext_id < count; ext_id++) {
		if (!array_is_created(&updates[ext_id]))
			continue;

		reset_id = ext_id < reset_id_count ? reset_ids[ext_id] : 0;
		log_append_ext_intro(ctx, ext_id, reset_id, &hdr_size);

		log_append_buffer(ctx, updates[ext_id].arr.buffer, type);
	}
}

static void
log_append_keyword_update(struct mail_index_export_context *ctx,
			  buffer_t *tmp_buf, enum modify_type modify_type,
			  const char *keyword, const buffer_t *uid_buffer)
{
	struct mail_transaction_keyword_update kt_hdr;

	i_assert(uid_buffer->used > 0);

	i_zero(&kt_hdr);
	kt_hdr.modify_type = modify_type;
	kt_hdr.name_size = strlen(keyword);

	buffer_set_used_size(tmp_buf, 0);
	buffer_append(tmp_buf, &kt_hdr, sizeof(kt_hdr));
	buffer_append(tmp_buf, keyword, kt_hdr.name_size);
	if ((tmp_buf->used % 4) != 0)
		buffer_append_zero(tmp_buf, 4 - (tmp_buf->used % 4));
	buffer_append(tmp_buf, uid_buffer->data, uid_buffer->used);

	log_append_buffer(ctx, tmp_buf, MAIL_TRANSACTION_KEYWORD_UPDATE);
}

static bool
log_append_keyword_updates(struct mail_index_export_context *ctx)
{
        const struct mail_index_transaction_keyword_update *updates;
	const char *const *keywords;
	buffer_t *tmp_buf;
	unsigned int i, count, keywords_count;
	bool changed = FALSE;

	tmp_buf = t_buffer_create(64);

	keywords = array_get_modifiable(&ctx->trans->view->index->keywords,
					&keywords_count);
	updates = array_get_modifiable(&ctx->trans->keyword_updates, &count);
	i_assert(count <= keywords_count);

	for (i = 0; i < count; i++) {
		if (array_is_created(&updates[i].add_seq) &&
		    array_count(&updates[i].add_seq) > 0) {
			changed = TRUE;
			log_append_keyword_update(ctx, tmp_buf,
					MODIFY_ADD, keywords[i],
					updates[i].add_seq.arr.buffer);
		}
		if (array_is_created(&updates[i].remove_seq) &&
		    array_count(&updates[i].remove_seq) > 0) {
			changed = TRUE;
			log_append_keyword_update(ctx, tmp_buf,
					MODIFY_REMOVE, keywords[i],
					updates[i].remove_seq.arr.buffer);
		}
	}
	return changed;
}

void mail_index_transaction_export(struct mail_index_transaction *t,
				   struct mail_transaction_log_append_ctx *append_ctx,
				   enum mail_index_transaction_change *changes_r)
{
	static uint8_t null4[4] = { 0, 0, 0, 0 };
	enum mail_index_fsync_mask change_mask = 0;
	struct mail_index_export_context ctx;

	*changes_r = 0;

	i_zero(&ctx);
	ctx.trans = t;
	ctx.append_ctx = append_ctx;

	if (t->index_undeleted) {
		i_assert(!t->index_deleted);
		mail_transaction_log_append_add(ctx.append_ctx,
			MAIL_TRANSACTION_INDEX_UNDELETED, &null4, 4);
	}

	/* send all extension introductions and resizes before appends
	   to avoid resize overhead as much as possible */
        mail_transaction_log_append_ext_intros(&ctx);

	if (t->pre_hdr_changed) {
		log_append_buffer(&ctx, log_get_hdr_update_buffer(t, TRUE),
				  MAIL_TRANSACTION_HEADER_UPDATE);
	}

	if (append_ctx->output->used > 0)
		*changes_r |= MAIL_INDEX_TRANSACTION_CHANGE_OTHERS;

	if (t->attribute_updates != NULL) {
		buffer_append_c(t->attribute_updates, '\0');
		/* need to have 32bit alignment */
		if (t->attribute_updates->used % 4 != 0) {
			buffer_append_zero(t->attribute_updates,
					   4 - t->attribute_updates->used % 4);
		}
		/* append the timestamp and value lengths */
		buffer_append(t->attribute_updates,
			      t->attribute_updates_suffix->data,
			      t->attribute_updates_suffix->used);
		i_assert(t->attribute_updates->used % 4 == 0);
		*changes_r |= MAIL_INDEX_TRANSACTION_CHANGE_ATTRIBUTE;
		log_append_buffer(&ctx, t->attribute_updates,
				  MAIL_TRANSACTION_ATTRIBUTE_UPDATE);
	}
	if (array_is_created(&t->appends)) {
		change_mask |= MAIL_INDEX_FSYNC_MASK_APPENDS;
		*changes_r |= MAIL_INDEX_TRANSACTION_CHANGE_APPEND;
		log_append_buffer(&ctx, t->appends.arr.buffer,
				  MAIL_TRANSACTION_APPEND);
	}

	if (array_is_created(&t->updates)) {
		change_mask |= MAIL_INDEX_FSYNC_MASK_FLAGS;
		*changes_r |= MAIL_INDEX_TRANSACTION_CHANGE_FLAGS;
		log_append_flag_updates(&ctx, t);
	}

	if (array_is_created(&t->ext_rec_updates)) {
		*changes_r |= MAIL_INDEX_TRANSACTION_CHANGE_OTHERS;
		log_append_ext_recs(&ctx, &t->ext_rec_updates,
				    MAIL_TRANSACTION_EXT_REC_UPDATE);
	}
	if (array_is_created(&t->ext_rec_atomics)) {
		*changes_r |= MAIL_INDEX_TRANSACTION_CHANGE_OTHERS;
		log_append_ext_recs(&ctx, &t->ext_rec_atomics,
				    MAIL_TRANSACTION_EXT_ATOMIC_INC);
	}

	if (array_is_created(&t->keyword_updates)) {
		if (log_append_keyword_updates(&ctx)) {
			change_mask |= MAIL_INDEX_FSYNC_MASK_KEYWORDS;
			*changes_r |= MAIL_INDEX_TRANSACTION_CHANGE_KEYWORDS;
		}
	}
	/* keep modseq updates almost last */
	if (array_is_created(&t->modseq_updates)) {
		*changes_r |= MAIL_INDEX_TRANSACTION_CHANGE_MODSEQ;
		log_append_buffer(&ctx, t->modseq_updates.arr.buffer,
				  MAIL_TRANSACTION_MODSEQ_UPDATE);
	}

	if (array_is_created(&t->expunges)) {
		/* non-external expunges are only requests, ignore them when
		   checking fsync_mask */
		if ((t->flags & MAIL_INDEX_TRANSACTION_FLAG_EXTERNAL) != 0) {
			change_mask |= MAIL_INDEX_FSYNC_MASK_EXPUNGES;
			*changes_r |= MAIL_INDEX_TRANSACTION_CHANGE_EXPUNGE;
		} else {
			*changes_r |= MAIL_INDEX_TRANSACTION_CHANGE_OTHERS;
		}
		log_append_buffer(&ctx, t->expunges.arr.buffer,
				  MAIL_TRANSACTION_EXPUNGE_GUID);
	}

	if (t->post_hdr_changed) {
		*changes_r |= MAIL_INDEX_TRANSACTION_CHANGE_OTHERS;
		log_append_buffer(&ctx, log_get_hdr_update_buffer(t, FALSE),
				  MAIL_TRANSACTION_HEADER_UPDATE);
	}

	if (t->index_deleted) {
		i_assert(!t->index_undeleted);
		*changes_r |= MAIL_INDEX_TRANSACTION_CHANGE_OTHERS;
		mail_transaction_log_append_add(ctx.append_ctx,
						MAIL_TRANSACTION_INDEX_DELETED,
						&null4, 4);
	}

	i_assert((append_ctx->output->used > 0) == (*changes_r != 0));

	append_ctx->index_sync_transaction = t->sync_transaction;
	append_ctx->tail_offset_changed = t->tail_offset_changed;
	append_ctx->want_fsync =
		(t->view->index->set.fsync_mask & change_mask) != 0 ||
		(t->flags & MAIL_INDEX_TRANSACTION_FLAG_FSYNC) != 0;
}