import sys
import os
from userconfig.cfgfile import Conf
import re
import time
import shutil


class Debug:
    _verbose = 0

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

    def set_verbose(self, verbose):
        self._verbose = verbose

    def add_verbose(self):
        self._verbose += 1

    def get_verbose(self):
        return self._verbose

    def stdout(self, out, level=0):
        if self._verbose >= level:
            print(out)

    def stderr(self, out, level=0):
        if self._verbose >= level:
            print(str(out)+"\n", file=sys.stderr)


def get_config(filename, cfg):
    """reads filename as config, checks for DEST parameter and returns cfgfile object"""
    try:
        ret = Conf(filename)
    except ValueError:
        cfg.debug.stderr("Error reading config file %s" % filename)
        return False
    # check for DEST parameter
    if not ret.check(section="Main", option="dest"):
        cfg.debug.stderr("No dest in config file %s" % filename)
        return False
    # make sure DEST ends with /
    if not ret.get(section="Main", option="dest").endswith("/"):
        ret.set(section="Main", option="dest", value=ret.get(section="Main", option="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(r"^\s+$", line)):
            yield line


def diff(destfile, tempfile, commentstring, cfg):
    """diff destfile and tempfile, returns True if files differ, False if they are the same"""
    cfg.debug.stdout("Diffing %s and %s, comment: %s" % (destfile, tempfile, commentstring), 3)
    if not os.path.isfile(destfile):
        cfg.debug.stdout("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
        cfg.debug.stderr("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()
            cfg.debug.stdout("%s differs, return true" % destfile, 3)
            return True
        # if differ
    # for line
    fp1.close()
    fp2.close()
    cfg.debug.stdout("%s is the same, return false" % destfile, 3)
    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("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("stamp")), line):
            return True
    return False


def backup_file(filename, cfg):
    """make backup of filename, returns True if backup is successful, False else"""
    if os.path.isfile(filename):
        cfg.debug.stdout("%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)
        cfg.debug.stdout("Renaming %s to %s" % (filename, testbackupname), 1)
        os.rename(filename, testbackupname)
        return True
    else:
        cfg.debug.stdout("%s does not exist, do not need backup." % filename, 3)
    return False


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

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