# Copyright 2019 (c) Anna Schumaker.
from . import version
import pathlib
import pickle
import xdg.BaseDirectory

__resource = "emmental"
if version.TESTING == True:
    __resource = "emmental-testing"
elif __debug__ == True:
    __resource = "emmental-debug"

READ  = 'rb'
WRITE = 'wb'
READ_TEXT  = 'r'
WRITE_TEXT = 'w'

emmental_data = pathlib.Path(xdg.BaseDirectory.save_data_path(__resource))

class DataFile:
    def __init__(self, path, mode):
        self.path = emmental_data / path
        self.temp = emmental_data / f".{path}.tmp"
        self.mode = mode
        self.file = None

    def __enter__(self):
        if self.mode in [ WRITE, WRITE_TEXT ]:
            self.file = self.temp.open(self.mode)
        elif self.mode in [ READ, READ_TEXT ] and self.path.exists():
            self.file = self.path.open(self.mode)
        return self

    def __exit__(self, exp_type, exp_value, traceback):
        if self.file:
            self.file.flush()
            self.file.close()
            if self.mode in [ WRITE, WRITE_TEXT ] and exp_type == None:
                self.temp.replace(self.path)
            self.file = None
        return exp_type == None

    def exists(self):
        return self.path.exists()

    def pickle(self, obj):
        if self.file:
            pickle.dump(obj, self.file, pickle.HIGHEST_PROTOCOL)

    def read(self):
        if self.file:
            return self.file.read()

    def remove(self):
        if self.file == None:
            self.path.unlink(missing_ok = True)

    def unpickle(self):
        if self.file:
            return pickle.load(self.file)

    def write(self, text):
        if self.file:
            self.file.write(text)