/*
 * Copyright 2013 (c) Anna Schumaker.
 */
#include <core/database.h>
#include <core/idle.h>

#define DB_ENTRY_AT(db, index) \
	(struct db_entry *)g_ptr_array_index(db->db_entries, index)


static void __dbe_free(struct database *db, struct db_entry *dbe)
{
	if (dbe) {
		g_hash_table_remove(db->db_keys, dbe->dbe_key);
		g_free(dbe->dbe_key);

		g_ptr_array_index(db->db_entries, dbe->dbe_index) = NULL;
		db->db_ops->dbe_free(dbe);

		db->db_size--;
	}
}

static struct db_entry *__dbe_next(const struct database *db, unsigned int index)
{
	if (!db->db_entries)
		return NULL;

	for (; index < db->db_entries->len; index++) {
		if (DB_ENTRY_AT(db, index))
			return DB_ENTRY_AT(db, index);
	}
	return NULL;
}

static struct db_entry *__dbe_read(struct database *db, unsigned int index)
{
	struct db_entry *dbe = NULL;

	if (file_readd(&db->db_file))
		dbe = db->db_ops->dbe_read(&db->db_file, index);

	g_ptr_array_index(db->db_entries, index) = dbe;
	return dbe;
}

static void __dbe_setup(struct database *db, unsigned int index)
{
	struct db_entry *dbe = DB_ENTRY_AT(db, index);

	if (dbe) {
		dbe->dbe_index = index;
		dbe->dbe_key   = db->db_ops->dbe_key(dbe);
		g_hash_table_insert(db->db_keys, dbe->dbe_key, dbe);
		db->db_size++;
	}
}

static void __dbe_write(struct database *db, struct db_entry *dbe)
{
	if (dbe) {
		file_writef(&db->db_file, "%u ", true);
		db->db_ops->dbe_write(&db->db_file, dbe);
	} else
		file_writef(&db->db_file, "%u", false);
	file_writef(&db->db_file, "\n");
}

void db_init(struct database *db, const char *filepath, bool autosave,
	     const struct db_ops *ops, unsigned int fmin)
{
	db->db_ops  = ops;
	db->db_size = 0;
	db->db_autosave = autosave;
	db->db_entries  = g_ptr_array_new();
	db->db_keys     = g_hash_table_new(g_str_hash, g_str_equal);
	file_init_data(&db->db_file, "", filepath, fmin);
}

void db_deinit(struct database *db)
{
	struct db_entry *dbe, *next;

	db_for_each(dbe, next, db)
		__dbe_free(db, dbe);

	g_ptr_array_free(db->db_entries, true);
	g_hash_table_destroy(db->db_keys);
	db->db_entries = NULL;
	db->db_keys    = NULL;
}

void db_save(struct database *db)
{
	if (file_open(&db->db_file, OPEN_WRITE) == false)
		return;

	file_writef(&db->db_file, "%u\n", db_actual_size(db));
	for (unsigned int i = 0; i < db_actual_size(db); i++)
		__dbe_write(db, DB_ENTRY_AT(db, i));

	file_close(&db->db_file);
}

void db_autosave(struct database *db)
{
	if (db->db_autosave == true)
		db_save(db);
}

void db_load(struct database *db)
{
	unsigned int size;
	bool save;

	if (file_open(&db->db_file, OPEN_READ) == false)
		return;

	size = file_readu(&db->db_file);
	g_ptr_array_set_size(db->db_entries, size);
	for (unsigned int i = 0; i < size; i++) {
		if (__dbe_read(db, i))
			__dbe_setup(db, i);
	}

	save = file_version(&db->db_file) != OCARINA_MINOR_VERSION;
	file_close(&db->db_file);

	if (save)
		db_autosave(db);
}

struct db_entry *db_insert(struct database *db, const gchar *key)
{
	struct db_entry *item = NULL;

	if (key)
		item = db->db_ops->dbe_alloc(key, db_actual_size(db));

	if (item) {
		g_ptr_array_add(db->db_entries, item);
		__dbe_setup(db, db_actual_size(db) - 1);
		db_autosave(db);
	}
	return item;
}

void db_remove(struct database *db, struct db_entry *item)
{
	if (item == NULL)
		return;
	if (db_at(db, item->dbe_index) != item)
		return;
	__dbe_free(db, item);
	db_autosave(db);
}

bool db_defrag(struct database *db)
{
	struct db_entry *dbe;
	unsigned int i, cur;

	if (db->db_size == db_actual_size(db))
		return false;

	for (cur = 0, i = 1; cur < db->db_size; cur++) {
		if (DB_ENTRY_AT(db, cur))
			continue;
		while (i <= cur || !DB_ENTRY_AT(db, i))
			i++;

		dbe = DB_ENTRY_AT(db, i);
		g_ptr_array_index(db->db_entries,   i) = NULL;
		g_ptr_array_index(db->db_entries, cur) = dbe;
		dbe->dbe_index = cur;
	}

	g_ptr_array_set_size(db->db_entries, db->db_size);
	db_autosave(db);
	return true;
}

void db_rekey(struct database *db, struct db_entry *dbe)
{
	if (dbe == NULL)
		return;

	g_hash_table_remove(db->db_keys, dbe->dbe_key);
	g_free(dbe->dbe_key);

	dbe->dbe_key = db->db_ops->dbe_key(dbe);
	g_hash_table_insert(db->db_keys, dbe->dbe_key, dbe);
}

unsigned int db_actual_size(const struct database *db)
{
	if (db->db_entries)
		return db->db_entries->len;
	return 0;
}

struct db_entry *db_first(const struct database *db)
{
	return __dbe_next(db, 0);
}

struct db_entry *db_next(const struct database *db, struct db_entry *ent)
{
	if (ent)
		return __dbe_next(db, ent->dbe_index + 1);
	return NULL;
}

struct db_entry *db_at(const struct database *db, unsigned int index)
{
	if (index >= db_actual_size(db))
		return NULL;
	return DB_ENTRY_AT(db, index);
}

struct db_entry *db_get(struct database *db, const gchar *key)
{
	return (struct db_entry *)g_hash_table_lookup(db->db_keys, key);
}

struct db_entry *db_find(struct database *db, const gchar *key)
{
	struct db_entry *dbe = db_get(db, key);
	if (dbe)
		return dbe;
	return db_insert(db, key);
}