#!/usr/bin/env python3

DB_PGSQL = 1
DB_SQLITE = 2

class Db:
	def __init__(self, obj, dbtype):
		self.obj = obj
		self.dbtype = dbtype

# Init PostgreSQL database
def init_pgsql(connect: str):
	global psycopg2
	import psycopg2
	return Db(psycopg2.connect(connect), DB_PGSQL)

# Init SQLite database
def init_sqlite(dbname: str):
	global sqlite3
	import sqlite3
	return Db(sqlite3.connect(dbname), DB_SQLITE)

def to_signed(x, bits=11):
	return x if x >= 0 else (1<<bits)-x

def from_signed(x, bits=11):
	b = 1<<bits
	return x if x < b else (b^x)-b

def chunk_to_int(pos: (int, int, int)):
	return to_signed(pos[2])<<24 | to_signed(pos[1])<<12 | to_signed(pos[0])

def int_to_chunk(pos: int):
	return (from_signed(pos>>24), from_signed(pos>>12&0xfff), from_signed(pos&0xfff))

# Read chunk from db
def get_chunk(db: Db, pos: (int, int, int)):
	if db.dbtype == DB_PGSQL:
		c = db.obj.cursor()
		c.execute("SELECT data FROM blocks WHERE posx={} AND posy={} AND posz={} LIMIT 1".format(*pos))
		res = c.fetchone()
		if res:
			res = res[0].tobytes()
		return res
	else:
		c = db.obj.cursor()
		c.execute("SELECT data FROM blocks WHERE pos={} LIMIT 1".format(chunk_to_int(pos)))
		res = c.fetchone()
		if res:
			res = res[0]
		return res

# Write chunk to db
def set_chunk(db: Db, pos: (int, int, int), data: bytes):
	if db.dbtype == DB_PGSQL:
		c = db.obj.cursor()
		c.execute("SELECT 1 FROM blocks WHERE posx={} AND posy={} AND posz={} LIMIT 1".format(*pos))
		if c.fetchone():
			c.execute("UPDATE blocks SET data={} WHERE posx={} AND posy={} AND posz={} LIMIT 1".format(data, *pos))
		else:
			c.execute("INSERT INTO blocks (posx, posy, posz, data) VALUES ({}, {}, {}, {})".format(*pos, data))
	else:
		chunk_id = chunk_to_int(pos)
		c.execute("SELECT 1 FROM blocks WHERE pos={} LIMIT 1".format(chunk_id))
		if c.fetchone():
			c.execute("UPDATE blocks SET data={} WHERE pos={} LIMIT 1".format(data, chunk_id))
		else:
			c.execute("INSERT INTO blocks (pos, data) VALUES ({}, {})".format(chunk_id, data))