"""Module for converting a FDB database to a SQLite database"""
import argparse
import os
import sqlite3
import struct
from collections import OrderedDict

# There seems to be no difference between 4 and 8, but just in case there is I'm keeping that type info
SQLITE_TYPE = {}
SQLITE_TYPE[0] = "none"
SQLITE_TYPE[1] = "int32"
SQLITE_TYPE[3] = "real"
SQLITE_TYPE[4] = "text_4"
SQLITE_TYPE[5] = "int_bool"
SQLITE_TYPE[6] = "int64"
SQLITE_TYPE[8] = "text_8"

def pointer_scope(func):
	"""The FDB format has a lot of pointers to structures, so this decorator automatically reads the pointer, seeks to the pointer position, calls the function, and seeks back."""
	def wrapper(self, *args, **kwargs):
		pointer = kwargs.get("pointer")

		if pointer == None:
			pointer = self._read_int32()
		else:
			del kwargs["pointer"]

		if pointer == -1:
			return

		current_pos = self.fdb.tell()
		self.fdb.seek(pointer)

		result = func(self, *args, **kwargs)

		self.fdb.seek(current_pos)
		return result
	return wrapper

# I'm using a class for this to save things like the fdb and the sqlite without using globals
class convert:
	def __init__(self, in_file, out_file=None, add_link_info=False):
		self.add_link_info = add_link_info
		if out_file == None:
			out_file = os.path.splitext(os.path.basename(in_file))[0] + ".sqlite"

		if os.path.exists(out_file):
			os.remove(out_file)

		self.fdb = open(in_file, "rb")
		self.sqlite = sqlite3.connect(out_file)

		self._read()
		print("-"*79)
		print("Finished converting database!")
		print("-"*79)

		self.sqlite.commit()
		self.sqlite.close()
		self.fdb.close()

	def _read(self):
		number_of_tables = self._read_int32()
		self._read_tables(number_of_tables)

	@pointer_scope
	def _read_tables(self, number_of_tables):
		for table_struct_index in range(number_of_tables):
			table_name, number_of_columns = self._read_column_header()
			print("[%2i%%] Reading table %s" % (table_struct_index*100//number_of_tables, table_name))
			self._read_row_header(table_name, number_of_columns)

	@pointer_scope
	def _read_column_header(self):
		number_of_columns = self._read_int32()
		table_name = self._read_string()
		columns = self._read_columns(number_of_columns)

		sql = "create table if not exists '%s' (%s)" % \
		(table_name,	", ".join(["'%s' %s" % (col, SQLITE_TYPE[columns[col]]) for col in columns]))

		self.sqlite.execute(sql)
		return table_name, len(columns)

	@pointer_scope
	def _read_columns(self, number_of_columns):
		columns = OrderedDict()

		for _ in range(number_of_columns):
			data_type = self._read_int32()
			name = self._read_string()
			columns[name] = data_type

		if self.add_link_info:
			columns["_linked_from"] = 1
			columns["_does_link"] = 5
			columns["_invalid"] = 5

		return columns

	@pointer_scope
	def _read_row_header(self, table_name, number_of_columns):
		number_of_allocated_rows = self._read_int32()
		if number_of_allocated_rows != 0:
			assert number_of_allocated_rows & (number_of_allocated_rows - 1) == 0 # assert power of 2 allocation size

		self.sqlite.executemany("insert into '%s' values (%s)" % (table_name, ", ".join(["?"] * number_of_columns)), self._read_rows(number_of_allocated_rows, number_of_columns))

	@pointer_scope
	def _read_rows(self, number_of_allocated_rows, number_of_columns):
		rowid = 0
		percent_read = -1 # -1 so 0% is displayed as new
		for row in range(number_of_allocated_rows):
			new_percent_read = row*100//number_of_allocated_rows
			if new_percent_read > percent_read:
				percent_read = new_percent_read
				print("[%2i%%] Reading rows" % percent_read, end="\r")

			row_pointer = self._read_int32()
			if row_pointer == -1:
				if self.add_link_info:
					yield (None,) * (number_of_columns-1) + (True,)	# invalid row
				rowid += 1
			else:
				linked_rows, rowid = self._read_row(rowid, pointer=row_pointer)
				for values in linked_rows:
					yield values

	@pointer_scope
	def _read_row(self, rowid):
		rows = []
		linked_from = None
		while True:
			row_values = self._read_row_info()
			linked = self._read_int32()
			if self.add_link_info:
				row_values.append(linked_from)
				row_values.append(linked != -1)
				row_values.append(False) # valid row
			rows.append(row_values)

			rowid += 1

			if linked == -1:
				break

			self.fdb.seek(linked)
			linked_from = rowid

		return rows, rowid

	@pointer_scope
	def _read_row_info(self):
		number_of_columns = self._read_int32()
		return self._read_row_values(number_of_columns)

	@pointer_scope
	def _read_row_values(self, number_of_columns):
		values = []

		for _ in range(number_of_columns):
			data_type = self._read_int32()
			if data_type == 0:
				assert self.fdb.read(4) == b"\0\0\0\0"
				value = None
			elif data_type == 1:
				value = self._read_int32()
			elif data_type == 3:
				value = struct.unpack("f", self.fdb.read(4))[0]
			elif data_type in (4, 8):
				value = self._read_string()
			elif data_type == 5:
				value = struct.unpack("?xxx", self.fdb.read(4))[0]
			elif data_type == 6:
				value = self._read_int64()
			else:
				raise NotImplementedError(data_type)

			values.append(value)
		return values


	def _read_int32(self):
		return struct.unpack("i", self.fdb.read(4))[0]

	@pointer_scope
	def _read_string(self):
		str_bytes = bytearray()
		while True:
			byte = self.fdb.read(1)
			if byte == b"\0":
				break
			str_bytes += byte
		return str_bytes.decode("latin1")

	@pointer_scope
	def _read_int64(self):
		return struct.unpack("q", self.fdb.read(8))[0]

if __name__ == "__main__":
	parser = argparse.ArgumentParser()
	parser.add_argument("fdb_path")
	parser.add_argument("--sqlite_path")
	parser.add_argument("--add_link_info", action="store_true")
	args = parser.parse_args()
	convert(args.fdb_path, args.sqlite_path, args.add_link_info)