# Copyright (C) 2008-2018 Jelmer Vernooij <jelmer@jelmer.uk>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA

"""Fetching from git into bzr."""

from dulwich.objects import (
    Commit,
    Tag,
    Tree,
    S_IFGITLINK,
    S_ISGITLINK,
    ZERO_SHA,
    )
from dulwich.object_store import (
    tree_lookup_path,
    )
import posixpath
import stat

from .. import (
    debug,
    errors,
    osutils,
    trace,
    )
from ..errors import (
    BzrError,
    )
from ..bzr.inventory import (
    InventoryDirectory,
    InventoryFile,
    InventoryLink,
    TreeReference,
    )
from ..revision import (
    NULL_REVISION,
    )
from ..bzr.inventorytree import InventoryRevisionTree
from ..bzr.testament import (
    StrictTestament3,
    )
from ..tree import InterTree
from ..tsort import (
    topo_sort,
    )
from ..bzr.versionedfile import (
    ChunkedContentFactory,
    )

from .mapping import (
    DEFAULT_FILE_MODE,
    decode_git_path,
    mode_is_executable,
    mode_kind,
    warn_unusual_mode,
    )
from .object_store import (
    LRUTreeCache,
    _tree_to_objects,
    )


def import_git_blob(texts, mapping, path, name, hexshas,
                    base_bzr_tree, parent_id, revision_id,
                    parent_bzr_trees, lookup_object, modes, store_updater,
                    lookup_file_id):
    """Import a git blob object into a bzr repository.

    :param texts: VersionedFiles to add to
    :param path: Path in the tree
    :param blob: A git blob
    :return: Inventory delta for this file
    """
    if not isinstance(path, bytes):
        raise TypeError(path)
    decoded_path = decode_git_path(path)
    (base_mode, mode) = modes
    (base_hexsha, hexsha) = hexshas
    if mapping.is_special_file(path):
        return []
    if base_hexsha == hexsha and base_mode == mode:
        # If nothing has changed since the base revision, we're done
        return []
    file_id = lookup_file_id(decoded_path)
    if stat.S_ISLNK(mode):
        cls = InventoryLink
    else:
        cls = InventoryFile
    ie = cls(file_id, decode_git_path(name), parent_id)
    if ie.kind == "file":
        ie.executable = mode_is_executable(mode)
    if base_hexsha == hexsha and mode_kind(base_mode) == mode_kind(mode):
        base_exec = base_bzr_tree.is_executable(decoded_path)
        if ie.kind == "symlink":
            ie.symlink_target = base_bzr_tree.get_symlink_target(decoded_path)
        else:
            ie.text_size = base_bzr_tree.get_file_size(decoded_path)
            ie.text_sha1 = base_bzr_tree.get_file_sha1(decoded_path)
        if ie.kind == "symlink" or ie.executable == base_exec:
            ie.revision = base_bzr_tree.get_file_revision(decoded_path)
        else:
            blob = lookup_object(hexsha)
    else:
        blob = lookup_object(hexsha)
        if ie.kind == "symlink":
            ie.revision = None
            ie.symlink_target = decode_git_path(blob.data)
        else:
            ie.text_size = sum(map(len, blob.chunked))
            ie.text_sha1 = osutils.sha_strings(blob.chunked)
    # Check what revision we should store
    parent_keys = []
    for ptree in parent_bzr_trees:
        intertree = InterTree.get(ptree, base_bzr_tree)
        try:
            ppath = intertree.find_source_paths(decoded_path, recurse='none')
        except errors.NoSuchFile:
            continue
        if ppath is None:
            continue
        pkind = ptree.kind(ppath)
        if (pkind == ie.kind and
            ((pkind == "symlink" and ptree.get_symlink_target(ppath) == ie.symlink_target) or
             (pkind == "file" and ptree.get_file_sha1(ppath) == ie.text_sha1 and
                ptree.is_executable(ppath) == ie.executable))):
            # found a revision in one of the parents to use
            ie.revision = ptree.get_file_revision(ppath)
            break
        parent_key = (file_id, ptree.get_file_revision(ppath))
        if parent_key not in parent_keys:
            parent_keys.append(parent_key)
    if ie.revision is None:
        # Need to store a new revision
        ie.revision = revision_id
        if ie.revision is None:
            raise ValueError("no file revision set")
        if ie.kind == 'symlink':
            chunks = []
        else:
            chunks = blob.chunked
        texts.insert_record_stream([
            ChunkedContentFactory((file_id, ie.revision),
                                  tuple(parent_keys), ie.text_sha1, chunks)])
    invdelta = []
    if base_hexsha is not None:
        old_path = decoded_path  # Renames are not supported yet
        if stat.S_ISDIR(base_mode):
            invdelta.extend(remove_disappeared_children(
                base_bzr_tree, old_path, lookup_object(base_hexsha), [],
                lookup_object))
    else:
        old_path = None
    invdelta.append((old_path, decoded_path, file_id, ie))
    if base_hexsha != hexsha:
        store_updater.add_object(blob, (ie.file_id, ie.revision), path)
    return invdelta


class SubmodulesRequireSubtrees(BzrError):
    _fmt = ("The repository you are fetching from contains submodules, "
            "which require a Bazaar format that supports tree references.")
    internal = False


def import_git_submodule(texts, mapping, path, name, hexshas,
                         base_bzr_tree, parent_id, revision_id,
                         parent_bzr_trees, lookup_object,
                         modes, store_updater, lookup_file_id):
    """Import a git submodule."""
    (base_hexsha, hexsha) = hexshas
    (base_mode, mode) = modes
    if base_hexsha == hexsha and base_mode == mode:
        return [], {}
    path = decode_git_path(path)
    file_id = lookup_file_id(path)
    invdelta = []
    ie = TreeReference(file_id, decode_git_path(name), parent_id)
    ie.revision = revision_id
    if base_hexsha is not None:
        old_path = path  # Renames are not supported yet
        if stat.S_ISDIR(base_mode):
            invdelta.extend(remove_disappeared_children(
                base_bzr_tree, old_path, lookup_object(base_hexsha), [],
                lookup_object))
    else:
        old_path = None
    ie.reference_revision = mapping.revision_id_foreign_to_bzr(hexsha)
    texts.insert_record_stream([
        ChunkedContentFactory((file_id, ie.revision), (), None, [])])
    invdelta.append((old_path, path, file_id, ie))
    return invdelta, {}


def remove_disappeared_children(base_bzr_tree, path, base_tree,
                                existing_children, lookup_object):
    """Generate an inventory delta for removed children.

    :param base_bzr_tree: Base bzr tree against which to generate the
        inventory delta.
    :param path: Path to process (unicode)
    :param base_tree: Git Tree base object
    :param existing_children: Children that still exist
    :param lookup_object: Lookup a git object by its SHA1
    :return: Inventory delta, as list
    """
    if not isinstance(path, str):
        raise TypeError(path)
    ret = []
    for name, mode, hexsha in base_tree.iteritems():
        if name in existing_children:
            continue
        c_path = posixpath.join(path, decode_git_path(name))
        file_id = base_bzr_tree.path2id(c_path)
        if file_id is None:
            raise TypeError(file_id)
        ret.append((c_path, None, file_id, None))
        if stat.S_ISDIR(mode):
            ret.extend(remove_disappeared_children(
                base_bzr_tree, c_path, lookup_object(hexsha), [],
                lookup_object))
    return ret


def import_git_tree(texts, mapping, path, name, hexshas,
                    base_bzr_tree, parent_id, revision_id, parent_bzr_trees,
                    lookup_object, modes, store_updater,
                    lookup_file_id, allow_submodules=False):
    """Import a git tree object into a bzr repository.

    :param texts: VersionedFiles object to add to
    :param path: Path in the tree (str)
    :param name: Name of the tree (str)
    :param tree: A git tree object
    :param base_bzr_tree: Base inventory against which to return inventory
        delta
    :return: Inventory delta for this subtree
    """
    (base_hexsha, hexsha) = hexshas
    (base_mode, mode) = modes
    if not isinstance(path, bytes):
        raise TypeError(path)
    if not isinstance(name, bytes):
        raise TypeError(name)
    if base_hexsha == hexsha and base_mode == mode:
        # If nothing has changed since the base revision, we're done
        return [], {}
    invdelta = []
    file_id = lookup_file_id(osutils.safe_unicode(path))
    ie = InventoryDirectory(file_id, decode_git_path(name), parent_id)
    tree = lookup_object(hexsha)
    if base_hexsha is None:
        base_tree = None
        old_path = None  # Newly appeared here
    else:
        base_tree = lookup_object(base_hexsha)
        old_path = decode_git_path(path)  # Renames aren't supported yet
    new_path = decode_git_path(path)
    if base_tree is None or type(base_tree) is not Tree:
        ie.revision = revision_id
        invdelta.append((old_path, new_path, ie.file_id, ie))
        texts.insert_record_stream([
            ChunkedContentFactory((ie.file_id, ie.revision), (), None, [])])
    # Remember for next time
    existing_children = set()
    child_modes = {}
    for name, child_mode, child_hexsha in tree.iteritems():
        existing_children.add(name)
        child_path = posixpath.join(path, name)
        if type(base_tree) is Tree:
            try:
                child_base_mode, child_base_hexsha = base_tree[name]
            except KeyError:
                child_base_hexsha = None
                child_base_mode = 0
        else:
            child_base_hexsha = None
            child_base_mode = 0
        if stat.S_ISDIR(child_mode):
            subinvdelta, grandchildmodes = import_git_tree(
                texts, mapping, child_path, name,
                (child_base_hexsha, child_hexsha), base_bzr_tree, file_id,
                revision_id, parent_bzr_trees, lookup_object,
                (child_base_mode, child_mode), store_updater, lookup_file_id,
                allow_submodules=allow_submodules)
        elif S_ISGITLINK(child_mode):  # submodule
            if not allow_submodules:
                raise SubmodulesRequireSubtrees()
            subinvdelta, grandchildmodes = import_git_submodule(
                texts, mapping, child_path, name,
                (child_base_hexsha, child_hexsha),
                base_bzr_tree, file_id, revision_id, parent_bzr_trees,
                lookup_object, (child_base_mode, child_mode), store_updater,
                lookup_file_id)
        else:
            if not mapping.is_special_file(name):
                subinvdelta = import_git_blob(
                    texts, mapping, child_path, name,
                    (child_base_hexsha, child_hexsha), base_bzr_tree, file_id,
                    revision_id, parent_bzr_trees, lookup_object,
                    (child_base_mode, child_mode), store_updater,
                    lookup_file_id)
            else:
                subinvdelta = []
            grandchildmodes = {}
        child_modes.update(grandchildmodes)
        invdelta.extend(subinvdelta)
        if child_mode not in (stat.S_IFDIR, DEFAULT_FILE_MODE,
                              stat.S_IFLNK, DEFAULT_FILE_MODE | 0o111,
                              S_IFGITLINK):
            child_modes[child_path] = child_mode
    # Remove any children that have disappeared
    if base_tree is not None and type(base_tree) is Tree:
        invdelta.extend(remove_disappeared_children(
            base_bzr_tree, old_path, base_tree, existing_children,
            lookup_object))
    store_updater.add_object(tree, (file_id, revision_id), path)
    return invdelta, child_modes


def verify_commit_reconstruction(target_git_object_retriever, lookup_object,
                                 o, rev, ret_tree, parent_trees, mapping,
                                 unusual_modes, verifiers):
    new_unusual_modes = mapping.export_unusual_file_modes(rev)
    if new_unusual_modes != unusual_modes:
        raise AssertionError("unusual modes don't match: %r != %r" % (
            unusual_modes, new_unusual_modes))
    # Verify that we can reconstruct the commit properly
    rec_o = target_git_object_retriever._reconstruct_commit(rev, o.tree, True,
                                                            verifiers)
    if rec_o != o:
        raise AssertionError("Reconstructed commit differs: %r != %r" % (
            rec_o, o))
    diff = []
    new_objs = {}
    for path, obj, ie in _tree_to_objects(
            ret_tree, parent_trees, target_git_object_retriever._cache.idmap,
            unusual_modes, mapping.BZR_DUMMY_FILE):
        old_obj_id = tree_lookup_path(lookup_object, o.tree, path)[1]
        new_objs[path] = obj
        if obj.id != old_obj_id:
            diff.append((path, lookup_object(old_obj_id), obj))
    for (path, old_obj, new_obj) in diff:
        while (old_obj.type_name == "tree"
               and new_obj.type_name == "tree"
               and sorted(old_obj) == sorted(new_obj)):
            for name in old_obj:
                if old_obj[name][0] != new_obj[name][0]:
                    raise AssertionError(
                        "Modes for %s differ: %o != %o" %
                        (path, old_obj[name][0], new_obj[name][0]))
                if old_obj[name][1] != new_obj[name][1]:
                    # Found a differing child, delve deeper
                    path = posixpath.join(path, name)
                    old_obj = lookup_object(old_obj[name][1])
                    new_obj = new_objs[path]
                    break
        raise AssertionError(
            "objects differ for %s: %r != %r" % (path, old_obj, new_obj))


def ensure_inventories_in_repo(repo, trees):
    real_inv_vf = repo.inventories.without_fallbacks()
    for t in trees:
        revid = t.get_revision_id()
        if not real_inv_vf.get_parent_map([(revid, )]):
            repo.add_inventory(revid, t.root_inventory, t.get_parent_ids())


def import_git_commit(repo, mapping, head, lookup_object,
                      target_git_object_retriever, trees_cache, strict):
    o = lookup_object(head)
    # Note that this uses mapping.revision_id_foreign_to_bzr. If the parents
    # were bzr roundtripped revisions they would be specified in the
    # roundtrip data.
    rev, roundtrip_revid, verifiers = mapping.import_commit(
        o, mapping.revision_id_foreign_to_bzr, strict)
    if roundtrip_revid is not None:
        original_revid = rev.revision_id
        rev.revision_id = roundtrip_revid
    # We have to do this here, since we have to walk the tree and
    # we need to make sure to import the blobs / trees with the right
    # path; this may involve adding them more than once.
    parent_trees = trees_cache.revision_trees(rev.parent_ids)
    ensure_inventories_in_repo(repo, parent_trees)
    if parent_trees == []:
        base_bzr_tree = trees_cache.revision_tree(NULL_REVISION)
        base_tree = None
        base_mode = None
    else:
        base_bzr_tree = parent_trees[0]
        base_tree = lookup_object(o.parents[0]).tree
        base_mode = stat.S_IFDIR
    store_updater = target_git_object_retriever._get_updater(rev)
    inv_delta, unusual_modes = import_git_tree(
        repo.texts, mapping, b"", b"", (base_tree, o.tree), base_bzr_tree,
        None, rev.revision_id, parent_trees, lookup_object,
        (base_mode, stat.S_IFDIR), store_updater,
        mapping.generate_file_id,
        allow_submodules=repo._format.supports_tree_reference)
    if unusual_modes != {}:
        for path, mode in unusual_modes.iteritems():
            warn_unusual_mode(rev.foreign_revid, path, mode)
        mapping.import_unusual_file_modes(rev, unusual_modes)
    try:
        basis_id = rev.parent_ids[0]
    except IndexError:
        basis_id = NULL_REVISION
        base_bzr_inventory = None
    else:
        base_bzr_inventory = base_bzr_tree.root_inventory
    rev.inventory_sha1, inv = repo.add_inventory_by_delta(
        basis_id, inv_delta, rev.revision_id, rev.parent_ids,
        base_bzr_inventory)
    ret_tree = InventoryRevisionTree(repo, inv, rev.revision_id)
    # Check verifiers
    if verifiers and roundtrip_revid is not None:
        testament = StrictTestament3(rev, ret_tree)
        calculated_verifiers = {"testament3-sha1": testament.as_sha1()}
        if calculated_verifiers != verifiers:
            trace.mutter("Testament SHA1 %r for %r did not match %r.",
                         calculated_verifiers["testament3-sha1"],
                         rev.revision_id, verifiers["testament3-sha1"])
            rev.revision_id = original_revid
            rev.inventory_sha1, inv = repo.add_inventory_by_delta(
                basis_id, inv_delta, rev.revision_id, rev.parent_ids,
                base_bzr_tree)
            ret_tree = InventoryRevisionTree(repo, inv, rev.revision_id)
    else:
        calculated_verifiers = {}
    store_updater.add_object(o, calculated_verifiers, None)
    store_updater.finish()
    trees_cache.add(ret_tree)
    repo.add_revision(rev.revision_id, rev)
    if "verify" in debug.debug_flags:
        verify_commit_reconstruction(
            target_git_object_retriever, lookup_object, o, rev, ret_tree,
            parent_trees, mapping, unusual_modes, verifiers)


def import_git_objects(repo, mapping, object_iter,
                       target_git_object_retriever, heads, pb=None,
                       limit=None):
    """Import a set of git objects into a bzr repository.

    :param repo: Target Bazaar repository
    :param mapping: Mapping to use
    :param object_iter: Iterator over Git objects.
    :return: Tuple with pack hints and last imported revision id
    """
    def lookup_object(sha):
        try:
            return object_iter[sha]
        except KeyError:
            return target_git_object_retriever[sha]
    graph = []
    checked = set()
    heads = list(set(heads))
    trees_cache = LRUTreeCache(repo)
    # Find and convert commit objects
    while heads:
        if pb is not None:
            pb.update("finding revisions to fetch", len(graph), None)
        head = heads.pop()
        if head == ZERO_SHA:
            continue
        if not isinstance(head, bytes):
            raise TypeError(head)
        try:
            o = lookup_object(head)
        except KeyError:
            continue
        if isinstance(o, Commit):
            rev, roundtrip_revid, verifiers = mapping.import_commit(
                o, mapping.revision_id_foreign_to_bzr, strict=True)
            if (repo.has_revision(rev.revision_id)
                    or (roundtrip_revid and
                        repo.has_revision(roundtrip_revid))):
                continue
            graph.append((o.id, o.parents))
            heads.extend([p for p in o.parents if p not in checked])
        elif isinstance(o, Tag):
            if o.object[1] not in checked:
                heads.append(o.object[1])
        else:
            trace.warning("Unable to import head object %r" % o)
        checked.add(o.id)
    del checked
    # Order the revisions
    # Create the inventory objects
    batch_size = 1000
    revision_ids = topo_sort(graph)
    pack_hints = []
    if limit is not None:
        revision_ids = revision_ids[:limit]
    last_imported = None
    for offset in range(0, len(revision_ids), batch_size):
        target_git_object_retriever.start_write_group()
        try:
            repo.start_write_group()
            try:
                for i, head in enumerate(
                        revision_ids[offset:offset + batch_size]):
                    if pb is not None:
                        pb.update("fetching revisions", offset + i,
                                  len(revision_ids))
                    import_git_commit(repo, mapping, head, lookup_object,
                                      target_git_object_retriever, trees_cache,
                                      strict=True)
                    last_imported = head
            except BaseException:
                repo.abort_write_group()
                raise
            else:
                hint = repo.commit_write_group()
                if hint is not None:
                    pack_hints.extend(hint)
        except BaseException:
            target_git_object_retriever.abort_write_group()
            raise
        else:
            target_git_object_retriever.commit_write_group()
    return pack_hints, last_imported


class DetermineWantsRecorder(object):

    def __init__(self, actual):
        self.actual = actual
        self.wants = []
        self.remote_refs = {}

    def __call__(self, refs):
        if type(refs) is not dict:
            raise TypeError(refs)
        self.remote_refs = refs
        self.wants = self.actual(refs)
        return self.wants
