# 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/.

from mozpack.files import (
    BaseFinder,
    JarFinder,
    ExecutableFile,
    BaseFile,
    GeneratedFile,
)
from mozpack.executables import (
    MACHO_SIGNATURES,
)
from mozpack.mozjar import JarReader
from mozpack.errors import errors
from tempfile import mkstemp
import mozpack.path
import struct
import os
import subprocess
from collections import OrderedDict


def may_unify_binary(file):
    '''
    Return whether the given BaseFile instance is an ExecutableFile that
    may be unified. Only non-fat Mach-O binaries are to be unified.
    '''
    if isinstance(file, ExecutableFile):
        signature = file.open().read(4)
        if len(signature) < 4:
            return False
        signature = struct.unpack('>L', signature)[0]
        if signature in MACHO_SIGNATURES:
            return True
    return False


class UnifiedExecutableFile(BaseFile):
    '''
    File class for executable and library files that to be unified with 'lipo'.
    '''
    def __init__(self, executable1, executable2):
        '''
        Initialize a UnifiedExecutableFile with a pair of ExecutableFiles to
        be unified. They are expected to be non-fat Mach-O executables.
        '''
        assert isinstance(executable1, ExecutableFile)
        assert isinstance(executable2, ExecutableFile)
        self._executables = (executable1, executable2)

    def copy(self, dest, skip_if_older=True):
        '''
        Create a fat executable from the two Mach-O executable given when
        creating the instance.
        skip_if_older is ignored.
        '''
        assert isinstance(dest, basestring)
        tmpfiles = []
        try:
            for e in self._executables:
                fd, f = mkstemp()
                os.close(fd)
                tmpfiles.append(f)
                e.copy(f, skip_if_older=False)
            subprocess.call(['lipo', '-create'] + tmpfiles + ['-output', dest])
        finally:
            for f in tmpfiles:
                os.unlink(f)


class UnifiedFinder(BaseFinder):
    '''
    Helper to get unified BaseFile instances from two distinct trees on the
    file system.
    '''
    def __init__(self, finder1, finder2, sorted=[], **kargs):
        '''
        Initialize a UnifiedFinder. finder1 and finder2 are BaseFinder
        instances from which files are picked. UnifiedFinder.find() will act as
        FileFinder.find() but will error out when matches can only be found in
        one of the two trees and not the other. It will also error out if
        matches can be found on both ends but their contents are not identical.

        The sorted argument gives a list of mozpack.path.match patterns. File
        paths matching one of these patterns will have their contents compared
        with their lines sorted.
        '''
        assert isinstance(finder1, BaseFinder)
        assert isinstance(finder2, BaseFinder)
        self._finder1 = finder1
        self._finder2 = finder2
        self._sorted = sorted
        BaseFinder.__init__(self, finder1.base, **kargs)

    def _find(self, path):
        '''
        UnifiedFinder.find() implementation.
        '''
        files1 = OrderedDict()
        for p, f in self._finder1.find(path):
            files1[p] = f
        files2 = set()
        for p, f in self._finder2.find(path):
            files2.add(p)
            if p in files1:
                if may_unify_binary(files1[p]) and \
                        may_unify_binary(f):
                    yield p, UnifiedExecutableFile(files1[p], f)
                else:
                    err = errors.count
                    unified = self.unify_file(p, files1[p], f)
                    if unified:
                        yield p, unified
                    elif err == errors.count:
                        self._report_difference(p, files1[p], f)
            else:
                errors.error('File missing in %s: %s' %
                             (self._finder1.base, p))
        for p in [p for p in files1 if not p in files2]:
            errors.error('File missing in %s: %s' % (self._finder2.base, p))

    def _report_difference(self, path, file1, file2):
        '''
        Report differences between files in both trees.
        '''
        errors.error("Can't unify %s: file differs between %s and %s" %
                     (path, self._finder1.base, self._finder2.base))
        if not isinstance(file1, ExecutableFile) and \
                not isinstance(file2, ExecutableFile):
            from difflib import unified_diff
            for line in unified_diff(file1.open().readlines(),
                                     file2.open().readlines(),
                                     os.path.join(self._finder1.base, path),
                                     os.path.join(self._finder2.base, path)):
                errors.out.write(line)

    def unify_file(self, path, file1, file2):
        '''
        Given two BaseFiles and the path they were found at, check whether
        their content match and return the first BaseFile if they do.
        '''
        content1 = file1.open().readlines()
        content2 = file2.open().readlines()
        if content1 == content2:
            return file1
        for pattern in self._sorted:
            if mozpack.path.match(path, pattern):
                if sorted(content1) == sorted(content2):
                    return file1
                break
        return None


class UnifiedBuildFinder(UnifiedFinder):
    '''
    Specialized UnifiedFinder for Mozilla applications packaging. It allows
    "*.manifest" files to differ in their order, and unifies "buildconfig.html"
    files by merging their content.
    '''
    def __init__(self, finder1, finder2, **kargs):
        UnifiedFinder.__init__(self, finder1, finder2,
                               sorted=['**/*.manifest'], **kargs)

    def unify_file(self, path, file1, file2):
        '''
        Unify buildconfig.html contents, or defer to UnifiedFinder.unify_file.
        '''
        if mozpack.path.basename(path) == 'buildconfig.html':
            content1 = file1.open().readlines()
            content2 = file2.open().readlines()
            # Copy everything from the first file up to the end of its <body>,
            # insert a <hr> between the two files and copy the second file's
            # content beginning after its leading <h1>.
            return GeneratedFile(''.join(
                content1[:content1.index('</body>\n')] +
                ['<hr> </hr>\n'] +
                content2[content2.index('<h1>about:buildconfig</h1>\n') + 1:]
            ))
        if path.endswith('.xpi'):
            finder1 = JarFinder(os.path.join(self._finder1.base, path),
                                JarReader(fileobj=file1.open()))
            finder2 = JarFinder(os.path.join(self._finder2.base, path),
                                JarReader(fileobj=file2.open()))
            unifier = UnifiedFinder(finder1, finder2, sorted=self._sorted)
            err = errors.count
            all(unifier.find(''))
            if err == errors.count:
                return file1
            return None
        return UnifiedFinder.unify_file(self, path, file1, file2)