# Copyright (C) 2010, 2011 Sebastian Thiel (byronimo@gmail.com) and contributors
#
# This module is part of GitDB and is released under
# the New BSD License: http://www.opensource.org/licenses/bsd-license.php
"""Contains basic implementations for the interface building blocks"""
from git.db.interface import *

from git.util import (
    pool,
    join,
    isfile,
    normpath,
    abspath,
    dirname,
    LazyMixin,
    hex_to_bin,
    bin_to_hex,
    expandvars,
    expanduser,
    exists,
    is_git_dir,
)

from git.index import IndexFile
from git.config import GitConfigParser
from git.exc import (
    BadObject,
    AmbiguousObjectName,
    InvalidGitRepositoryError,
    NoSuchPathError
)

from async import ChannelThreadTask

from itertools import chain
import sys
import os


__all__ = ('PureObjectDBR', 'PureObjectDBW', 'PureRootPathDB', 'PureCompoundDB',
           'PureConfigurationMixin', 'PureRepositoryPathsMixin', 'PureAlternatesFileMixin',
           'PureIndexDB')


class PureObjectDBR(ObjectDBR):

    #{ Query Interface

    def has_object_async(self, reader):
        task = ChannelThreadTask(reader, str(self.has_object_async), lambda sha: (sha, self.has_object(sha)))
        return pool.add_task(task)

    def info_async(self, reader):
        task = ChannelThreadTask(reader, str(self.info_async), self.info)
        return pool.add_task(task)

    def stream_async(self, reader):
        # base implementation just uses the stream method repeatedly
        task = ChannelThreadTask(reader, str(self.stream_async), self.stream)
        return pool.add_task(task)

    def partial_to_complete_sha_hex(self, partial_hexsha):
        len_partial_hexsha = len(partial_hexsha)
        if len_partial_hexsha % 2 != 0:
            partial_binsha = hex_to_bin(partial_hexsha + "0")
        else:
            partial_binsha = hex_to_bin(partial_hexsha)
        # END assure successful binary conversion
        return self.partial_to_complete_sha(partial_binsha, len(partial_hexsha))

    #} END query interface


class PureObjectDBW(ObjectDBW):

    def __init__(self, *args, **kwargs):
        try:
            super(PureObjectDBW, self).__init__(*args, **kwargs)
        except TypeError:
            pass
        # END handle py 2.6
        self._ostream = None

    #{ Edit Interface
    def set_ostream(self, stream):
        cstream = self._ostream
        self._ostream = stream
        return cstream

    def ostream(self):
        return self._ostream

    def store_async(self, reader):
        task = ChannelThreadTask(reader, str(self.store_async), self.store)
        return pool.add_task(task)

    #} END edit interface


class PureRootPathDB(RootPathDB):

    def __init__(self, root_path):
        self._root_path = root_path
        super(PureRootPathDB, self).__init__(root_path)

    #{ Interface
    def root_path(self):
        return self._root_path

    def db_path(self, rela_path=None):
        if not rela_path:
            return self._root_path
        return join(self._root_path, rela_path)
    #} END interface


def _databases_recursive(database, output):
    """Fill output list with database from db, in order. Deals with Loose, Packed 
    and compound databases."""
    if isinstance(database, CompoundDB):
        compounds = list()
        dbs = database.databases()
        output.extend(db for db in dbs if not isinstance(db, CompoundDB))
        for cdb in (db for db in dbs if isinstance(db, CompoundDB)):
            _databases_recursive(cdb, output)
    else:
        output.append(database)
    # END handle database type


class PureCompoundDB(CompoundDB, PureObjectDBR, LazyMixin, CachingDB):

    def _set_cache_(self, attr):
        if attr == '_dbs':
            self._dbs = list()
        else:
            super(PureCompoundDB, self)._set_cache_(attr)

    #{ PureObjectDBR interface

    def has_object(self, sha):
        for db in self._dbs:
            if db.has_object(sha):
                return True
        # END for each db
        return False

    def info(self, sha):
        for db in self._dbs:
            try:
                return db.info(sha)
            except BadObject:
                pass
        # END for each db

    def stream(self, sha):
        for db in self._dbs:
            try:
                return db.stream(sha)
            except BadObject:
                pass
        # END for each db

    def size(self):
        return reduce(lambda x, y: x + y, (db.size() for db in self._dbs), 0)

    def sha_iter(self):
        return chain(*(db.sha_iter() for db in self._dbs))

    #} END object DBR Interface

    #{ Interface

    def databases(self):
        return tuple(self._dbs)

    def update_cache(self, force=False):
        # something might have changed, clear everything
        stat = False
        for db in self._dbs:
            if isinstance(db, CachingDB):
                stat |= db.update_cache(force)
            # END if is caching db
        # END for each database to update
        return stat

    def partial_to_complete_sha_hex(self, partial_hexsha):
        len_partial_hexsha = len(partial_hexsha)
        if len_partial_hexsha % 2 != 0:
            partial_binsha = hex_to_bin(partial_hexsha + "0")
        else:
            partial_binsha = hex_to_bin(partial_hexsha)
        # END assure successful binary conversion

        candidate = None
        for db in self._dbs:
            full_bin_sha = None
            try:
                if hasattr(db, 'partial_to_complete_sha_hex'):
                    full_bin_sha = db.partial_to_complete_sha_hex(partial_hexsha)
                else:
                    full_bin_sha = db.partial_to_complete_sha(partial_binsha, len_partial_hexsha)
                # END handle database type
            except BadObject:
                continue
            # END ignore bad objects
            if full_bin_sha:
                if candidate and candidate != full_bin_sha:
                    raise AmbiguousObjectName(partial_hexsha)
                candidate = full_bin_sha
            # END handle candidate
        # END for each db
        if not candidate:
            raise BadObject(partial_binsha)
        return candidate

    def partial_to_complete_sha(self, partial_binsha, hex_len):
        """Simple adaptor to feed into our implementation"""
        return self.partial_to_complete_sha_hex(bin_to_hex(partial_binsha)[:hex_len])
    #} END interface


class PureRepositoryPathsMixin(RepositoryPathsMixin):
    # slots has no effect here, its just to keep track of used attrs
    __slots__ = ("_git_path", '_bare', '_working_tree_dir')

    #{ Configuration
    repo_dir = '.git'
    objs_dir = 'objects'
    #} END configuration

    #{ Subclass Interface
    def _initialize(self, path):
        epath = abspath(expandvars(expanduser(path or os.getcwd())))

        if not exists(epath):
            raise NoSuchPathError(epath)
        # END check file

        self._working_tree_dir = None
        self._git_path = None
        curpath = epath

        # walk up the path to find the .git dir
        while curpath:
            if is_git_dir(curpath):
                self._git_path = curpath
                self._working_tree_dir = os.path.dirname(curpath)
                break
            gitpath = join(curpath, self.repo_dir)
            if is_git_dir(gitpath):
                self._git_path = gitpath
                self._working_tree_dir = curpath
                break
            curpath, dummy = os.path.split(curpath)
            if not dummy:
                break
        # END while curpath

        if self._git_path is None:
            raise InvalidGitRepositoryError(epath)
        # END path not found

        self._bare = self._working_tree_dir is None
        if hasattr(self, 'config_reader'):
            try:
                self._bare = self.config_reader("repository").getboolean('core', 'bare')
            except Exception:
                # lets not assume the option exists, although it should
                pass
            # END handle exception
        # END check bare flag
        self._working_tree_dir = self._bare and None or self._working_tree_dir

    #} end subclass interface

    #{ Object Interface

    def __eq__(self, rhs):
        if hasattr(rhs, 'git_dir'):
            return self.git_dir == rhs.git_dir
        return False

    def __ne__(self, rhs):
        return not self.__eq__(rhs)

    def __hash__(self):
        return hash(self.git_dir)

    def __repr__(self):
        return "%s(%r)" % (type(self).__name__, self.git_dir)

    #} END object interface

    #{ Interface

    @property
    def is_bare(self):
        return self._bare

    @property
    def git_dir(self):
        return self._git_path

    @property
    def working_tree_dir(self):
        if self._working_tree_dir is None:
            raise AssertionError("Repository at %s is bare and does not have a working tree directory" % self.git_dir)
        # END assertion
        return dirname(self.git_dir)

    @property
    def objects_dir(self):
        return join(self.git_dir, self.objs_dir)

    @property
    def working_dir(self):
        if self.is_bare:
            return self.git_dir
        else:
            return self.working_tree_dir
        # END handle bare state

    def _mk_description():
        def _get_description(self):
            filename = join(self.git_dir, 'description')
            return file(filename).read().rstrip()

        def _set_description(self, descr):
            filename = join(self.git_dir, 'description')
            file(filename, 'w').write(descr + '\n')

        return property(_get_description, _set_description, "Descriptive text for the content of the repository")

    description = _mk_description()
    del(_mk_description)

    #} END interface


class PureConfigurationMixin(ConfigurationMixin):

    #{ Configuration
    system_config_file_name = "gitconfig"
    repo_config_file_name = "config"
    #} END

    def __new__(cls, *args, **kwargs):
        """This is just a stupid workaround for the evil py2.6 change which makes mixins quite impossible"""
        return super(PureConfigurationMixin, cls).__new__(cls, *args, **kwargs)

    def __init__(self, *args, **kwargs):
        """Verify prereqs"""
        try:
            super(PureConfigurationMixin, self).__init__(*args, **kwargs)
        except TypeError:
            pass
        # END handle code-breaking change in python 2.6
        assert hasattr(self, 'git_dir')

    def _path_at_level(self, level):
        # we do not support an absolute path of the gitconfig on windows ,
        # use the global config instead
        if sys.platform == "win32" and level == "system":
            level = "global"
        # END handle windows

        if level == "system":
            return "/etc/%s" % self.system_config_file_name
        elif level == "global":
            return normpath(expanduser("~/.%s" % self.system_config_file_name))
        elif level == "repository":
            return join(self.git_dir, self.repo_config_file_name)
        # END handle level

        raise ValueError("Invalid configuration level: %r" % level)

    #{ Interface

    def config_reader(self, config_level=None):
        files = None
        if config_level is None:
            files = [self._path_at_level(f) for f in self.config_level]
        else:
            files = [self._path_at_level(config_level)]
        # END handle level
        return GitConfigParser(files, read_only=True)

    def config_writer(self, config_level="repository"):
        return GitConfigParser(self._path_at_level(config_level), read_only=False)

    #} END interface


class PureIndexDB(IndexDB):
    #{ Configuration
    IndexCls = IndexFile
    #} END configuration

    @property
    def index(self):
        return self.IndexCls(self)


class PureAlternatesFileMixin(object):

    """Utility able to read and write an alternates file through the alternates property
    It needs to be part of a type with the git_dir or db_path property.

    The file by default is assumed to be located at the default location as imposed
    by the standard git repository layout"""

    #{ Configuration
    alternates_filepath = os.path.join('info', 'alternates')    # relative path to alternates file

    #} END configuration

    def __init__(self, *args, **kwargs):
        try:
            super(PureAlternatesFileMixin, self).__init__(*args, **kwargs)
        except TypeError:
            pass
        # END handle py2.6 code breaking changes
        self._alternates_path()  # throws on incompatible type

    #{ Interface

    def _alternates_path(self):
        if hasattr(self, 'git_dir'):
            return join(self.git_dir, 'objects', self.alternates_filepath)
        elif hasattr(self, 'db_path'):
            return self.db_path(self.alternates_filepath)
        else:
            raise AssertionError("This mixin requires a parent type with either the git_dir property or db_path method")
        # END handle path

    def _get_alternates(self):
        """The list of alternates for this repo from which objects can be retrieved

        :return: list of strings being pathnames of alternates"""
        alternates_path = self._alternates_path()

        if os.path.exists(alternates_path):
            try:
                f = open(alternates_path)
                alts = f.read()
            finally:
                f.close()
            return alts.strip().splitlines()
        else:
            return list()
        # END handle path exists

    def _set_alternates(self, alts):
        """Sets the alternates

        :parm alts:
            is the array of string paths representing the alternates at which 
            git should look for objects, i.e. /home/user/repo/.git/objects

        :raise NoSuchPathError:
        :note:
            The method does not check for the existance of the paths in alts
            as the caller is responsible."""
        alternates_path = self._alternates_path()
        if not alts:
            if isfile(alternates_path):
                os.remove(alternates_path)
        else:
            try:
                f = open(alternates_path, 'w')
                f.write("\n".join(alts))
            finally:
                f.close()
            # END file handling
        # END alts handling

    alternates = property(_get_alternates, _set_alternates,
                          doc="Retrieve a list of alternates paths or set a list paths to be used as alternates")

    #} END interface