#!/usr/bin/python
# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

# originally from https://hg.mozilla.org/build/tools/file/4ab9c1a4e05b/scripts/release/compare-mozconfigs.py  # NOQA: E501

import difflib
import logging
import os
import unittest

import mozunit

here = os.path.abspath(os.path.dirname(__file__))

FAILURE_CODE = 1
SUCCESS_CODE = 0

PLATFORMS = (
    "linux64",
    "macosx64",
    "win32",
    "win64",
    "win64-aarch64",
)

log = logging.getLogger(__name__)


class ConfigError(Exception):
    pass


def readConfig(configfile):
    c = {}
    with open(configfile) as config:
        exec(config.read(), c)
    return c["allowlist"]


def verify_mozconfigs(
    mozconfig_pair, nightly_mozconfig_pair, platform, mozconfigAllowlist
):
    """Compares mozconfig to nightly_mozconfig and compare to an optional
    allowlist of known differences. mozconfig_pair and nightly_mozconfig_pair
    are pairs containing the mozconfig's identifier and the list of lines in
    the mozconfig."""

    # unpack the pairs to get the names, the names are just for
    # identifying the mozconfigs when logging the error messages
    mozconfig_name, mozconfig_lines = mozconfig_pair
    nightly_mozconfig_name, nightly_mozconfig_lines = nightly_mozconfig_pair

    if not mozconfig_lines or not nightly_mozconfig_lines:
        log.info("Missing mozconfigs to compare for %s" % platform)
        return False

    success = True

    diff_instance = difflib.Differ()
    diff_result = diff_instance.compare(mozconfig_lines, nightly_mozconfig_lines)
    diff_list = list(diff_result)

    for line in diff_list:
        clean_line = line[1:].strip()
        if (line[0] == "-" or line[0] == "+") and len(clean_line) > 1:
            # skip comment lines
            if clean_line.startswith("#"):
                continue
            # compare to allowlist
            message = ""
            if line[0] == "-":
                # handle lines that move around in diff
                if "+" + line[1:] in diff_list:
                    continue
                if platform in mozconfigAllowlist.get("release", {}):
                    if clean_line in mozconfigAllowlist["release"][platform]:
                        continue
            elif line[0] == "+":
                if "-" + line[1:] in diff_list:
                    continue
                if platform in mozconfigAllowlist.get("nightly", {}):
                    if clean_line in mozconfigAllowlist["nightly"][platform]:
                        continue
                    else:
                        log.warning(
                            "%s not in %s %s!"
                            % (
                                clean_line,
                                platform,
                                mozconfigAllowlist["nightly"][platform],
                            )
                        )
            else:
                log.error("Skipping line %s!" % line)
                continue
            message = "found in %s but not in %s: %s"
            if line[0] == "-":
                log.error(
                    message % (mozconfig_name, nightly_mozconfig_name, clean_line)
                )
            else:
                log.error(
                    message % (nightly_mozconfig_name, mozconfig_name, clean_line)
                )
            success = False
    return success


def get_mozconfig(path):
    """Consumes a path and returns a list of lines from the mozconfig file."""
    with open(path) as fh:
        return fh.readlines()


def compare(topsrcdir):
    app = os.path.join(topsrcdir, "browser")
    allowlist = readConfig(os.path.join(app, "config", "mozconfigs", "allowlist"))

    success = True

    def normalize_lines(lines):
        return {l.strip() for l in lines}

    for platform in PLATFORMS:
        log.info("Comparing platform %s" % platform)

        mozconfigs_path = os.path.join(app, "config", "mozconfigs", platform)

        nightly_path = os.path.join(mozconfigs_path, "nightly")
        beta_path = os.path.join(mozconfigs_path, "beta")
        release_path = os.path.join(mozconfigs_path, "release")

        nightly_lines = get_mozconfig(nightly_path)
        beta_lines = get_mozconfig(beta_path)
        release_lines = get_mozconfig(release_path)

        # Validate that entries in allowlist['nightly'][platform] are actually
        # present.
        allowlist_normalized = normalize_lines(allowlist["nightly"].get(platform, []))
        nightly_normalized = normalize_lines(nightly_lines)

        for line in sorted(allowlist_normalized - nightly_normalized):
            log.error("extra line in nightly allowlist: %s" % line)
            success = False

        log.info("Comparing beta and nightly mozconfigs")
        passed = verify_mozconfigs(
            (beta_path, beta_lines), (nightly_path, nightly_lines), platform, allowlist
        )

        if not passed:
            success = False

        log.info("Comparing release and nightly mozconfigs")
        passed = verify_mozconfigs(
            (release_path, release_lines),
            (nightly_path, nightly_lines),
            platform,
            allowlist,
        )
        if not passed:
            success = False

    return success


class TestCompareMozconfigs(unittest.TestCase):
    def test_compare_mozconfigs(self):
        topsrcdir = os.path.abspath(os.path.join(here, "..", ".."))
        self.assertTrue(compare(topsrcdir))


if __name__ == "__main__":
    logging.basicConfig(level=logging.INFO)
    mozunit.main()