#!/usr/bin/env python
#
# Copyright (c) 2016 ARM Limited
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from abc import ABCMeta, abstractmethod
from datetime import datetime
import difflib
import functools
import os
import re
from six import add_metaclass
import subprocess
import sys
import traceback

sys.path.append(os.path.dirname(__file__))
from results import UnitResult
from helpers import *

_test_base = os.path.join(os.path.dirname(__file__), "..")

@add_metaclass(ABCMeta)
class TestUnit(object):
    """Base class for all test units.

    A test unit is a part of a larger test case. Test cases usually
    contain two types of units, run units (run gem5) and verify units
    (diff output files). All unit implementations inherit from this
    class.

    A unit implementation overrides the _run() method. The test runner
    calls the run() method, which wraps _run() to protect against
    exceptions.

    """

    def __init__(self, name, ref_dir, test_dir, skip=False):
        self.name = name
        self.ref_dir = ref_dir
        self.test_dir = test_dir
        self.force_skip = skip
        self.start_time = None
        self.stop_time = None

    def result(self, state, **kwargs):
        if self.start_time is not None and "runtime" not in kwargs:
            self.stop_time = datetime.utcnow()
            delta = self.stop_time - self.start_time
            kwargs["runtime"] = delta.total_seconds()

        return UnitResult(self.name, state, **kwargs)

    def ok(self, **kwargs):
        return self.result(UnitResult.STATE_OK, **kwargs)

    def skip(self, **kwargs):
        return self.result(UnitResult.STATE_SKIPPED, **kwargs)

    def error(self, message, **kwargs):
        return self.result(UnitResult.STATE_ERROR, message=message, **kwargs)

    def failure(self, message, **kwargs):
        return self.result(UnitResult.STATE_FAILURE, message=message, **kwargs)

    def ref_file(self, fname):
        return os.path.join(self.ref_dir, fname)

    def out_file(self, fname):
        return os.path.join(self.test_dir, fname)

    def _read_output(self, fname, default=""):
        try:
            with open(self.out_file(fname), "r") as f:
                return f.read()
        except IOError:
            return default

    def run(self):
        self.start_time = datetime.utcnow()
        try:
            if self.force_skip:
                return self.skip()
            else:
                return self._run()
        except:
            return self.error("Python exception:\n%s" % traceback.format_exc())

    @abstractmethod
    def _run(self):
        pass

class RunGem5(TestUnit):
    """Test unit representing a gem5 run.

    Possible failure modes:
       - gem5 failed to run -> STATE_ERROR
       - timeout -> STATE_ERROR
       - non-zero exit code -> STATE_ERROR

    Possible non-failure results:
       - exit code == 0 -> STATE_OK
       - exit code == 2 -> STATE_SKIPPED
    """

    def __init__(self, gem5, gem5_args, timeout=0, **kwargs):
        super(RunGem5, self).__init__("gem5", **kwargs)
        self.gem5 = gem5
        self.args = gem5_args
        self.timeout = timeout

    def _run(self):
        gem5_cmd = [
            self.gem5,
            "-d", self.test_dir,
            "--stats-file", "text://stats.txt?desc=False",
            "-re",
        ] + self.args

        try:
            with ProcessHelper(gem5_cmd, stdout=subprocess.PIPE,
                               stderr=subprocess.PIPE) as p:
                status, gem5_stdout, gem5_stderr = p.call(timeout=self.timeout)
        except CallTimeoutException as te:
            return self.error("Timeout", stdout=te.stdout, stderr=te.stderr)
        except OSError as ose:
            return self.error("Failed to launch gem5: %s" % ose)

        stderr = "\n".join([
            "*** gem5 stderr ***",
            gem5_stderr,
            "",
            "*** m5out/simerr ***",
            self._read_output("simerr"),
        ])

        stdout = "\n".join([
            "*** gem5 stdout ***",
            gem5_stdout,
            "",
            "*** m5out/simout ***",
            self._read_output("simout"),
        ])

        # Signal
        if status < 0:
            return self.error("gem5 terminated by signal %i" % (-status, ),
                              stdout=stdout, stderr=stderr)
        elif status == 2:
            return self.skip(stdout=stdout, stderr=stderr)
        elif status > 0:
            return self.error("gem5 exited with non-zero status: %i" % status,
                              stdout=stdout, stderr=stderr)
        else:
            return self.ok(stdout=stdout, stderr=stderr)

class DiffOutFile(TestUnit):
    """Test unit comparing and output file and a reference file."""

    # regular expressions of lines to ignore when diffing outputs
    diff_ignore_regexes = {
        "simout" : [
            re.compile('^Redirecting (stdout|stderr) to'),
            re.compile('^gem5 compiled '),
            re.compile('^gem5 started '),
            re.compile('^gem5 executing on '),
            re.compile('^command line:'),
            re.compile("^Couldn't import dot_parser,"),
            re.compile("^info: kernel located at:"),
            re.compile("^Couldn't unlink "),
            re.compile("^Using GPU kernel code file\(s\) "),
        ],
        "simerr" : [
            #re.compile('^Simulation complete at'),
        ],
        "config.ini" : [
            re.compile("^(executable|readfile|kernel|image_file)="),
            re.compile("^(cwd|input|codefile)="),
        ],
        "config.json" : [
            re.compile(r'''^\s*"(executable|readfile|kernel|image_file)":'''),
            re.compile(r'''^\s*"(cwd|input|codefile)":'''),
        ],
    }

    def __init__(self, fname, **kwargs):
        super(DiffOutFile, self).__init__("diff[%s]" % fname,
                                          **kwargs)

        self.fname = fname
        self.line_filters = DiffOutFile.diff_ignore_regexes.get(fname, tuple())

    def _filter_file(self, fname):
        def match_line(l):
            for r in self.line_filters:
                if r.match(l):
                    return True
            return False

        with open(fname, "r") as f:
            for l in f:
                if not match_line(l):
                    yield l


    def _run(self):
        fname = self.fname
        ref = self.ref_file(fname)
        out = self.out_file(fname)

        if not os.path.exists(ref):
            return self.error("%s doesn't exist in reference directory" \
                              % fname)

        if not os.path.exists(out):
            return self.error("%s doesn't exist in output directory" % fname)

        diff = difflib.unified_diff(
            tuple(self._filter_file(ref)),
            tuple(self._filter_file(out)),
            fromfile="ref/%s" % fname, tofile="out/%s" % fname)

        diff = list(diff)
        if diff:
            return self.error("ref/%s and out/%s differ" % (fname, fname),
                              stderr="".join(diff))
        else:
            return self.ok(stdout="-- ref/%s and out/%s are identical --" \
                           % (fname, fname))

class DiffStatFile(TestUnit):
    """Test unit comparing two gem5 stat files."""

    def __init__(self, **kwargs):
        super(DiffStatFile, self).__init__("stat_diff", **kwargs)

        self.stat_diff = os.path.join(_test_base, "diff-out")

    def _run(self):
        STATUS_OK = 0
        STATUS_NEW_STATS = 1
        STATUS_FAILED = 2

        stats = "stats.txt"

        cmd = [
            self.stat_diff,
            self.ref_file(stats), self.out_file(stats),
        ]
        with ProcessHelper(cmd,
                           stdout=subprocess.PIPE,
                           stderr=subprocess.PIPE) as p:
            status, stdout, stderr = p.call()

        if status in (STATUS_OK, STATUS_NEW_STATS):
            return self.ok(stdout=stdout, stderr=stderr)
        elif status == STATUS_FAILED:
            return self.failure("Statistics mismatch",
                                stdout=stdout, stderr=stderr)
        else:
            return self.error("diff-out returned an error: %i" % status,
                              stdout=stdout, stderr=stderr)