info.py

#!/usr/bin/python3

import os
import subprocess

TMPNAME = '.pardatabase_tmp_file'       # Temporary file used when generating .par2

class Info:
    "Info on filepaths within system"

    def __init__(self, pathname=None, load=None, base='.'):

        if load:
            # Load from json dict
            for key, val in load.items():
                setattr(self, key, val)
        else:
            self.pathname = pathname        # Relative path (can be changed between runs)
            self.hash = None
            self.mtime = None
            self.size = None

        self.fullpath = os.path.join(base, self.pathname)
        self.cwd = os.path.dirname(self.fullpath)

        if not load:
            self.update()


    def tojson(self,):
        "Return neccesary variables as compact json dict."
        return {key:val for key, val in vars(self).items() if key in ['pathname', 'hash', 'mtime', 'size']}


    def update(self,):
        "Update file size and mtime"
        self.mtime = os.path.getmtime(self.fullpath)
        self.size = os.path.getsize(self.fullpath)


    def find_tmp(self,):
        "Find existing par2 tmp files"
        for name in os.listdir(self.cwd):
            if name.endswith('.par2') and name.startswith(TMPNAME):
                yield os.path.join(self.cwd, name)


    def remove_existing(self,):
        "Delete leftover .par2 files"
        for name in self.find_tmp():
            print("Removing existing par2 file:", name)
            os.remove(name)


    def repair(self, dest_files):
        "Attempt to repair a file with the files found in the database"
        cmd = "par2 repair".split() + [sorted(dest_files)[0]] + [self.fullpath]
        print('\n' + ' '.join(cmd))
        ret = subprocess.run(cmd, check=False, cwd=self.cwd)
        status = not ret.returncode
        if status:
            for file in dest_files:
                os.remove(file)
        return status


    def run_par2(self, par2_options, name, verbose=False):
        '''Run par2 command
        par2_options are passed to par2
        name is the alterate name in case the file needs to be renamed
        '''
        self.remove_existing()
        cmd = "par2 create -n1 -qq".split()
        if par2_options:
            cmd.extend(('-' + par2_options).split())
        cmd += ['-a', TMPNAME + '.par2', '--', os.path.basename(name)]
        if verbose:
            print(' '.join(cmd))
        return subprocess.Popen(cmd, stdout=subprocess.DEVNULL, cwd=self.cwd)