/*  Copyright (C) 2021 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#include "knot/journal/journal_metadata.h"

#include "libknot/endian.h"
#include "libknot/error.h"

static void fix_endian(void *data, size_t data_size, bool in)
{
	union {
		uint8_t  u8;
		uint16_t u16;
		uint32_t u32;
		uint64_t u64;
	} before, after;

	memcpy(&before, data, data_size);
	switch (data_size) {
	case sizeof(uint8_t):
		return;
	case sizeof(uint16_t):
		after.u16 = in ? be16toh(before.u16) : htobe16(before.u16);
		break;
	case sizeof(uint32_t):
		after.u32 = in ? be32toh(before.u32) : htobe32(before.u32);
		break;
	case sizeof(uint64_t):
		after.u64 = in ? be64toh(before.u64) : htobe64(before.u64);
		break;
	default:
		assert(0);
	}
	memcpy(data, &after, data_size);
}

static MDB_val metadata_key(const knot_dname_t *zone, const char *metadata)
{
	if (zone == NULL) {
		return knot_lmdb_make_key("IS", (uint32_t)0, metadata);
	} else {
		return knot_lmdb_make_key("NIS", zone, (uint32_t)0, metadata);
	}
}

static bool del_metadata(knot_lmdb_txn_t *txn, const knot_dname_t *zone, const char *metadata)
{
	MDB_val key = metadata_key(zone, metadata);
	if (key.mv_data != NULL) {
		knot_lmdb_del_prefix(txn, &key);
		free(key.mv_data);
	}
	return (key.mv_data != NULL);
}

static bool get_metadata(knot_lmdb_txn_t *txn, const knot_dname_t *zone, const char *metadata)
{
	MDB_val key = metadata_key(zone, metadata);
	bool ret = knot_lmdb_find(txn, &key, KNOT_LMDB_EXACT); // not FORCE
	free(key.mv_data);
	return ret;
}

static bool get_metadata_numeric(knot_lmdb_txn_t *txn, const knot_dname_t *zone,
                                 const char *metadata, void *result, size_t result_size)
{
	if (get_metadata(txn, zone, metadata)) {
		if (txn->cur_val.mv_size == result_size) {
			memcpy(result, txn->cur_val.mv_data, result_size);
			fix_endian(result, result_size, true);
			return true;
		} else {
			txn->ret = KNOT_EMALF;
		}
	}
	return false;
}

bool get_metadata32(knot_lmdb_txn_t *txn, const knot_dname_t *zone,
                    const char *metadata, uint32_t *result)
{
	return get_metadata_numeric(txn, zone, metadata, result, sizeof(*result));
}

bool get_metadata64(knot_lmdb_txn_t *txn, const knot_dname_t *zone,
                    const char *metadata, uint64_t *result)
{
	return get_metadata_numeric(txn, zone, metadata, result, sizeof(*result));
}

bool get_metadata64or32(knot_lmdb_txn_t *txn, const knot_dname_t *zone,
			const char *metadata, uint64_t *result)
{
	if (txn->ret != KNOT_EOK) {
		return false;
	}
	bool ret = get_metadata64(txn, zone, metadata, result);
	if (txn->ret == KNOT_EMALF) {
		uint32_t res32 = 0;
		txn->ret = KNOT_EOK;
		ret = get_metadata32(txn, zone, metadata, &res32);
		*result = res32;
	}
	return ret;
}

void set_metadata(knot_lmdb_txn_t *txn, const knot_dname_t *zone, const char *metadata,
                  const void *valp, size_t val_size, bool numeric)
{
	MDB_val key = metadata_key(zone, metadata);
	MDB_val val = { val_size, NULL };
	if (knot_lmdb_insert(txn, &key, &val)) {
		memcpy(val.mv_data, valp, val_size);
		if (numeric) {
			fix_endian(val.mv_data, val_size, false);
		}
	}
	free(key.mv_data);
}

static int64_t last_occupied_diff(knot_lmdb_txn_t *txn)
{
	uint64_t occupied_now = knot_lmdb_usage(txn), occupied_last = 0;
	(void)get_metadata64(txn, NULL, "last_total_occupied", &occupied_last);
	return (int64_t)occupied_now - (int64_t)occupied_last;
}

void update_last_inserter(knot_lmdb_txn_t *txn, const knot_dname_t *new_inserter)
{
	uint64_t occupied_now = knot_lmdb_usage(txn), lis_occupied = 0;
	int64_t occupied_diff = last_occupied_diff(txn);
	knot_dname_t *last_inserter = get_metadata(txn, NULL, "last_inserter_zone") ?
	                              knot_dname_copy(txn->cur_val.mv_data, NULL) : NULL;
	if (occupied_diff == 0 || last_inserter == NULL) {
		goto update_inserter;
	}
	(void)get_metadata64(txn, last_inserter, "occupied", &lis_occupied);
	lis_occupied = MAX(0, (int64_t)lis_occupied + occupied_diff);
	set_metadata(txn, last_inserter, "occupied", &lis_occupied, sizeof(lis_occupied), true);

update_inserter:
	if (new_inserter == NULL) {
		del_metadata(txn, NULL, "last_inserter_zone");
	} else if (last_inserter == NULL || !knot_dname_is_equal(last_inserter, new_inserter)) {
		set_metadata(txn, NULL, "last_inserter_zone", new_inserter, knot_dname_size(new_inserter), false);
	}
	free(last_inserter);
	set_metadata(txn, NULL, "last_total_occupied", &occupied_now, sizeof(occupied_now), true);
}

uint64_t journal_get_occupied(knot_lmdb_txn_t *txn, const knot_dname_t *zone)
{
	uint64_t res = 0;
	get_metadata64(txn, zone, "occupied", &res);
	return res;
}

static int first_digit(char * of)
{
	unsigned maj, min;
	return sscanf(of, "%u.%u", &maj, &min) == 2 ? maj : -1;
}

void journal_load_metadata(knot_lmdb_txn_t *txn, const knot_dname_t *zone, journal_metadata_t *md)
{
	memset(md, 0, sizeof(*md));
	if (get_metadata(txn, NULL, "version")) {
		switch (first_digit(txn->cur_val.mv_data)) {
		case 3:
			// TODO warning about downgrade
			// FALLTHROUGH
		case 1:
			// still supported
			// FALLTHROUGH
		case 2:
			// normal operation
			break;
		case 0:
			// failed to read version
			txn->ret = KNOT_ENOENT;
			return;
		default:
			txn->ret = KNOT_ENOTSUP;
			return;
		}
	}
	md->_new_zone = !get_metadata32(txn, zone, "flags", &md->flags);
	(void)get_metadata32(txn, zone, "first_serial",    &md->first_serial);
	(void)get_metadata32(txn, zone, "last_serial_to",  &md->serial_to);
	(void)get_metadata32(txn, zone, "merged_serial",   &md->merged_serial);
	(void)get_metadata32(txn, zone, "changeset_count", &md->changeset_count);
	if (!get_metadata32(txn, zone, "flushed_upto", &md->flushed_upto)) {
		// importing from version 1.0
		if ((md->flags & JOURNAL_LAST_FLUSHED_VALID)) {
			uint32_t last_flushed = 0;
			if (!get_metadata32(txn, zone, "last_flushed", &last_flushed) ||
			    !journal_serial_to(txn, false, last_flushed, zone, &md->flushed_upto)) {
				txn->ret = KNOT_EMALF;
			} else {
				md->flags &= ~JOURNAL_LAST_FLUSHED_VALID;
			}
		} else {
			md->flushed_upto = md->first_serial;
		}
	}

}

void journal_store_metadata(knot_lmdb_txn_t *txn, const knot_dname_t *zone, const journal_metadata_t *md)
{
	set_metadata(txn, zone, "first_serial",    &md->first_serial,    sizeof(md->first_serial),    true);
	set_metadata(txn, zone, "last_serial_to",  &md->serial_to,       sizeof(md->serial_to),       true);
	set_metadata(txn, zone, "flushed_upto",    &md->flushed_upto,    sizeof(md->flushed_upto),    true);
	set_metadata(txn, zone, "merged_serial",   &md->merged_serial,   sizeof(md->merged_serial),   true);
	set_metadata(txn, zone, "changeset_count", &md->changeset_count, sizeof(md->changeset_count), true);
	set_metadata(txn, zone, "flags",           &md->flags,           sizeof(md->flags),           true);
	set_metadata(txn, NULL, "version", "2.0", 4, false);
	if (md->_new_zone) {
		uint64_t journal_count = 0;
		(void)get_metadata64or32(txn, NULL, "journal_count", &journal_count);
		++journal_count;
		set_metadata(txn, NULL, "journal_count", &journal_count, sizeof(journal_count), true);
	}
}

void journal_metadata_after_delete(journal_metadata_t *md, uint32_t deleted_upto,
                                   size_t deleted_count)
{
	if (deleted_count == 0) {
		return;
	}
	assert((md->flags & JOURNAL_SERIAL_TO_VALID));
	if (deleted_upto == md->serial_to) {
		assert(md->flushed_upto == md->serial_to);
		assert(md->changeset_count == deleted_count);
		md->flags &= ~JOURNAL_SERIAL_TO_VALID;
	}
	md->first_serial = deleted_upto;
	md->changeset_count -= deleted_count;
}

void journal_metadata_after_merge(journal_metadata_t *md, bool merged_zij, uint32_t merged_serial,
                                  uint32_t merged_serial_to, uint32_t original_serial_to)
{
	md->flushed_upto = merged_serial_to;
	if ((md->flags & JOURNAL_MERGED_SERIAL_VALID)) {
		assert(!merged_zij);
		assert(merged_serial == md->merged_serial);
	} else if (!merged_zij) {
		md->merged_serial = merged_serial;
		md->flags |= JOURNAL_MERGED_SERIAL_VALID;
		assert(merged_serial == md->first_serial);
		journal_metadata_after_delete(md, original_serial_to, 1); // the merged changeset writes itself instead of first one
	}
}

void journal_metadata_after_insert(journal_metadata_t *md, uint32_t serial, uint32_t serial_to)
{
	if (md->first_serial == md->serial_to) { // no changesets yet
		md->first_serial = serial;
		md->flushed_upto = serial;
	}
	md->serial_to = serial_to;
	md->flags |= JOURNAL_SERIAL_TO_VALID;
	md->changeset_count++;
}

void journal_metadata_after_extra(journal_metadata_t *md, uint32_t serial, uint32_t serial_to)
{
	assert(!(md->flags & JOURNAL_MERGED_SERIAL_VALID));
	md->merged_serial = serial;
	md->flushed_upto = serial_to;
	md->flags |= (JOURNAL_MERGED_SERIAL_VALID | JOURNAL_LAST_FLUSHED_VALID);
}

void journal_del_zone_txn(knot_lmdb_txn_t *txn, const knot_dname_t *zone)
{
	uint64_t md_occupied = 0;
	(void)get_metadata64(txn, zone, "occupied", &md_occupied);
	journal_del_zone(txn, zone);
	set_metadata(txn, zone, "occupied", &md_occupied, sizeof(md_occupied), true);
}

int journal_scrape_with_md(zone_journal_t j, bool check_existence)
{
	if (check_existence && !journal_is_existing(j)) {
		return KNOT_EOK;
	}
	knot_lmdb_txn_t txn = { 0 };
	knot_lmdb_begin(j.db, &txn, true);

	update_last_inserter(&txn, NULL);
	journal_del_zone(&txn, j.zone);

	knot_lmdb_commit(&txn);
	return txn.ret;
}

int journal_copy_with_md(knot_lmdb_db_t *from, knot_lmdb_db_t *to, const knot_dname_t *zone)
{
	knot_lmdb_txn_t tr = { 0 }, tw = { 0 };
	tr.ret = knot_lmdb_open(from);
	tw.ret = knot_lmdb_open(to);
	if (tr.ret != KNOT_EOK || tw.ret != KNOT_EOK) {
		goto done;
	}
	knot_lmdb_begin(from, &tr, true);
	knot_lmdb_begin(to, &tw, true);
	update_last_inserter(&tr, NULL);
	MDB_val prefix = journal_zone_prefix(zone);
	knot_lmdb_copy_prefix(&tr, &tw, &prefix);
	free(prefix.mv_data);
	knot_lmdb_commit(&tw);
	knot_lmdb_commit(&tr);
done:
	return tr.ret == KNOT_EOK ? tw.ret : tr.ret;
}

int journal_set_flushed(zone_journal_t j)
{
	knot_lmdb_txn_t txn = { 0 };
	journal_metadata_t md = { 0 };
	knot_lmdb_begin(j.db, &txn, true);
	journal_load_metadata(&txn, j.zone, &md);

	md.flushed_upto = md.serial_to;

	journal_store_metadata(&txn, j.zone, &md);
	knot_lmdb_commit(&txn);
	return txn.ret;
}

int journal_info(zone_journal_t j, bool *exists, uint32_t *first_serial, bool *has_zij,
                 uint32_t *serial_to, bool *has_merged, uint32_t *merged_serial,
                 uint64_t *occupied, uint64_t *occupied_total)
{
	if (knot_lmdb_exists(j.db) == KNOT_ENODB) {
		*exists = false;
		return KNOT_EOK;
	}
	int ret = knot_lmdb_open(j.db);
	if (ret != KNOT_EOK) {
		return ret;
	}
	knot_lmdb_txn_t txn = { 0 };
	journal_metadata_t md = { 0 };
	knot_lmdb_begin(j.db, &txn, false);
	journal_load_metadata(&txn, j.zone, &md);
	*exists = (md.flags & JOURNAL_SERIAL_TO_VALID);
	if (first_serial != NULL) {
		*first_serial = md.first_serial;
	}
	if (has_zij != NULL) {
		*has_zij = journal_contains(&txn, true, 0, j.zone);
	}
	if (serial_to != NULL) {
		*serial_to = md.serial_to;
	}
	if (has_merged != NULL) {
		*has_merged = (md.flags & JOURNAL_MERGED_SERIAL_VALID);
	}
	if (merged_serial != NULL) {
		*merged_serial = md.merged_serial;
	}
	if (occupied != NULL) {
		*occupied = 0;
		get_metadata64(&txn, j.zone, "occupied", occupied);

		if (get_metadata(&txn, NULL, "last_inserter_zone") &&
		    knot_dname_is_equal(j.zone, txn.cur_val.mv_data)) {
			*occupied = MAX(0, (int64_t)*occupied + last_occupied_diff(&txn));
		}
	}
	if (occupied_total != NULL) {
		*occupied_total = knot_lmdb_usage(&txn);
	}
	knot_lmdb_abort(&txn);
	return txn.ret;
}

int journals_walk(knot_lmdb_db_t *db, journals_walk_cb_t cb, void *ctx)
{
	int ret = knot_lmdb_exists(db);
	if (ret == KNOT_EOK) {
		ret = knot_lmdb_open(db);
	}
	if (ret != KNOT_EOK) {
		return ret;
	}
	knot_lmdb_txn_t txn = { 0 };
	knot_lmdb_begin(db, &txn, false);
	knot_dname_storage_t search_data = { 0 };
	MDB_val search = { 1, search_data };
	while (knot_lmdb_find(&txn, &search, KNOT_LMDB_GEQ)) {
		knot_dname_t *found = txn.cur_key.mv_data;
		uint32_t unused_flags;
		if (get_metadata32(&txn, found, "flags", &unused_flags)) {
			// matched journal DB key appears to be a zone name
			txn.ret = cb(found, ctx);
		}

		// update searched key to next after found zone
		search.mv_size = knot_dname_size(found);
		memcpy(search.mv_data, found, search.mv_size);
		((uint8_t *)search.mv_data)[search.mv_size - 1]++;
	}
	knot_lmdb_abort(&txn);
	return txn.ret;
}