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import codecs
import re


class CrashLogs(object):

    PID_LINE_REGEX = re.compile(r'\s+Global\s+PID:\s+\[(?P<pid>\d+)\]')

    def __init__(self, host, results_directory=None):
        self._host = host
        self._results_directory = results_directory

    def find_newest_log(self, process_name, pid=None, include_errors=False, newer_than=None):
        if self._host.platform.is_mac():
            return self._find_newest_log_darwin(process_name, pid, include_errors, newer_than)
        elif self._host.platform.is_win():
            return self._find_newest_log_win(process_name, pid, include_errors, newer_than)
        return None

    def _log_directory_darwin(self):
        log_directory = self._host.filesystem.expanduser("~")
        log_directory = self._host.filesystem.join(log_directory, "Library", "Logs")
        if self._host.filesystem.exists(self._host.filesystem.join(log_directory, "DiagnosticReports")):
            log_directory = self._host.filesystem.join(log_directory, "DiagnosticReports")
        else:
            log_directory = self._host.filesystem.join(log_directory, "CrashReporter")
        return log_directory

    def _find_newest_log_darwin(self, process_name, pid, include_errors, newer_than):
        def is_crash_log(fs, dirpath, basename):
            return basename.startswith(process_name + "_") and basename.endswith(".crash")

        log_directory = self._log_directory_darwin()
        logs = self._host.filesystem.files_under(log_directory, file_filter=is_crash_log)
        first_line_regex = re.compile(r'^Process:\s+(?P<process_name>.*) \[(?P<pid>\d+)\]$')
        errors = ''
        for path in reversed(sorted(logs)):
            try:
                if not newer_than or self._host.filesystem.mtime(path) > newer_than:
                    f = self._host.filesystem.read_text_file(path)
                    match = first_line_regex.match(f[0:f.find('\n')])
                    if match and match.group('process_name') == process_name and (pid is None or int(match.group('pid')) == pid):
                        return errors + f
            except IOError, e:
                if include_errors:
                    errors += "ERROR: Failed to read '%s': %s\n" % (path, str(e))
            except OSError, e:
                if include_errors:
                    errors += "ERROR: Failed to read '%s': %s\n" % (path, str(e))

        if include_errors and errors:
            return errors
        return None

    def _find_newest_log_win(self, process_name, pid, include_errors, newer_than):
        def is_crash_log(fs, dirpath, basename):
            return basename.startswith("CrashLog")

        logs = self._host.filesystem.files_under(self._results_directory, file_filter=is_crash_log)
        errors = ''
        for path in reversed(sorted(logs)):
            try:
                if not newer_than or self._host.filesystem.mtime(path) > newer_than:
                    log_file = self._host.filesystem.read_binary_file(path).decode('utf8', 'ignore')
                    match = self.PID_LINE_REGEX.search(log_file)
                    if match is None:
                        continue
                    if int(match.group('pid')) == pid:
                        return errors + log_file
            except IOError, e:
                print "IOError %s" % str(e)
                if include_errors:
                    errors += "ERROR: Failed to read '%s': %s\n" % (path, str(e))
            except OSError, e:
                print "OSError %s" % str(e)
                if include_errors:
                    errors += "ERROR: Failed to read '%s': %s\n" % (path, str(e))
            except UnicodeDecodeError, e:
                print "UnicodeDecodeError %s" % str(e)
                if include_errors:
                    errors += "ERROR: Failed to decode '%s' as utf8: %s\n" % (path, str(e))

        if include_errors and errors:
            return errors
        return None