#!/usr/bin/env python3
# encoding: utf-8

"""
Tools.py

Created by Marcus Stoegbauer on 2013-01-12.
"""

import sys
import os
import Userconfig.cfgfile as cfgfile
import re
import time
import shutil


class Debug(object):
    verbose = 0

    def __init__(self, verbose=0):
        self.setverbose(verbose)

    def setverbose(self, verbose):
        """docstring for setverbose"""
        self.verbose = verbose

    def addverbose(self):
        """docstring for setverbose"""
        self.verbose += 1

    def debug(self, out, level=0):
        """docstring for debug"""
        if self.verbose >= level:
            print(out)


def error(out):
    """Print error on stderr"""
    print(str(out)+"\n", file=sys.stderr)


def get_config(filename):
    """reads filename as config, checks for DEST parameter and returns cfgfile object"""
    ret = None
    try:
        ret = cfgfile.Conf(filename)
    except:
        error("Error reading config file %s" % filename)
        return False

    # check for DEST parameter
    if not ret.check("Main", "dest"):
        error("No DEST in config file %s" % filename)
        return False

    # replace $HOME with real home directory
    if ret.get("Main", "dest") == "$HOME":
        ret.set("Main", "dest", os.environ['HOME'])

    # make sure DEST ends with /
    if not ret.get("Main", "dest").endswith("/"):
        ret.set("Main", "dest", ret.get("Main", "dest")+"/")

    return ret


def read_skip_comment(fp, commentstring):
    """Read line from filehandle fp and skip all empty (whitespace) lines and lines starting with commentstring
    """
    for line in fp:
        line = line[:-1]
        if (commentstring != "" and not re.match("^"+re.escape(commentstring), line)) and line !="" and not re.match("^\s+$", line):
            yield line


def diff(destfile, tempfile, commentstring, debug):
    """diff destfile and tempfile, returns True if files differ, False if they are the same"""
    debug.debug("Diffing %s and %s" % (destfile, tempfile), 3)
    if not os.path.isfile(destfile):
        debug.debug("Destfile %s does not exist, returning True." % destfile, 3)
        # destfile does not exist -> copy tempfile over
        return True
    # if not destfile
    if not os.path.isfile(tempfile):
        # tempfile does not exist, this should never happen
        error("Temporary file %s does not exist, this should not happen." % tempfile)
        sys.exit(1)
    # if not tempfile

    fp1 = open(tempfile)
    fp2 = open(destfile)

    for line1, line2 in zip(read_skip_comment(fp1, commentstring), read_skip_comment(fp2, commentstring)):
        if line1 != line2:
            fp1.close()
            fp2.close()
            return True
        # if differ
    # for line
    fp1.close()
    fp2.close()
    return False


def user_config_generated(filename, cfg):
    """returns True if filename has been generated by userconfig, False else"""

    if not os.path.isfile(filename):
        # filename does not exist, so it was not generated by userconfig
        return False

    if not cfg.check("Main","stamp"):
        # no STAMP in userconfig.cfg, so no way to check if file was generated by userconfig
        return False

    fp = open(filename, "r")

    for line in fp:
        if re.search(re.escape(cfg.get("Main","stamp")), line):
            return True
    return False


def backup_file(filename, debug):
    """make backup of filename, returns True if backup is successful, False else"""
    if os.path.isfile(filename):
        debug.debug("%s exists, finding backup name." % filename, 3)
        backupname = filename+".userconfig."+time.strftime("%F")
        testbackupname = backupname
        counter = 0
        while os.path.isfile(testbackupname):
            counter+=1
            testbackupname=backupname+"."+str(counter)
        debug.debug("Renaming %s to %s" % (filename, testbackupname), 1)
        os.rename(filename, testbackupname)
        return True
    else:
        debug.debug("%s does not exist, do not need backup." % filename, 3)
    return False


def copy_file(sourcefile, destfile, debug):
    """copy sourcefile to destfile, returns True if successful, False else"""

    if os.path.isfile(sourcefile):
        # sourcefile exists
        debug.debug("Source file %s exists, proceeding with copy." % sourcefile, 3)
        if not os.path.isfile(destfile) or os.access(destfile, os.W_OK):
            debug.debug("Copying %s to %s" % (sourcefile, destfile), 1)
            shutil.copy(sourcefile, destfile)
            return True
            # destfile is writable
        else:
            debug.debug("Destination file %s does not exist or is not writable." % destfile, 3)
    return False