from datetime import datetime, timedelta
import os
import StringIO
from time import mktime

from bzrlib import branch, diff, errors

from pyvcs.commit import Commit
from pyvcs.exceptions import CommitDoesNotExist, FileDoesNotExist, FolderDoesNotExist
from pyvcs.repository import BaseRepository

class Repository(BaseRepository):
    def __init__(self, *args, **kwargs):
        super(Repository, self).__init__(*args, **kwargs)

        # API-wise, pyvcs's notion of a "repository" probably maps more closely
        # to bzr's notion of a branch than of a bzr repository so, self._branch
        # is the bzrlib Branch structure mapping to the path in question.
        self._branch = branch.Branch.open(self.path.rstrip(os.path.sep))

    # for purposes of naming, "commit ID" is used as pyvcs uses it: to describe
    # the user-facing name for a revision ("revision number" or "revno" in bzr
    # terms); "revision_id" or "rev_id" is used here to describe bzrlib's
    # internal string names for revisions. Finally, "rev" refers to an actual
    # bzrlib revision structure.
    def _rev_to_commit(self, rev):
        # TODO: this doesn't yet handle the case of multiple parent revisions
        current = self._branch.repository.revision_tree(rev.revision_id)
        if len(rev.parent_ids):
            prev = self._branch.repository.revision_tree(rev.parent_ids[0])
        else:
            prev = self._branch.repository.revision_tree('null:')

        delta = current.changes_from(prev)
        files = [f[0] for f in delta.added + delta.removed + delta.renamed + delta.kind_changed + delta.modified]

        diff_file = StringIO.StringIO()

        diff_tree = diff.DiffTree(prev, current, diff_file)

        self._branch.lock_read()
        diff_tree.show_diff('')
        self._branch.unlock()

        diff_out = diff_file.getvalue()
        diff_file.close()

        return Commit(self._get_commit_id(rev.revision_id), rev.committer,
            datetime.fromtimestamp(rev.timestamp), rev.message, files, diff_out)

    def _get_rev_id(self, commit_id):
        return self._branch.get_rev_id(int(commit_id))

    def _get_commit_id(self, rev_id):
        return self._branch.revision_id_to_revno(rev_id)

    def _get_commit_by_rev_id(self, rev_id):
        rev = self._branch.repository.get_revision(rev_id)
        return self._rev_to_commit(rev)

    def get_commit_by_id(self, commit_id):
        rev_id = self._get_rev_id(commit_id)
        return self._get_commit_by_rev_id(rev_id)

    def _get_tree(self, revision=None):
        if revision:
            return self._branch.repository.revision_tree(self._get_rev_id(revision))
        else:
            return self._branch.repository.revision_tree(self._branch.last_revision())

    def get_recent_commits(self, since=None):
        hist = self._branch.revision_history()
        hist.reverse()
        head = hist[0]

        if since is None:
            since = datetime.fromtimestamp(head.timestamp) - timedelta(days=5)

        since_ts = mktime(since.timetuple())

        commits = []
        for rev_id in hist:
            rev = self._branch.repository.get_revision(rev_id)
            if rev.timestamp < since_ts:
                break
            commits.append(self._rev_to_commit(rev))

        return commits

    def list_directory(self, path, revision=None):
        path = path.rstrip(os.path.sep)
        tree = self._get_tree(revision)
        dir_iter = tree.walkdirs(path)
        try:
            entries = dir_iter.next()
        except StopIteration:
            raise FolderDoesNotExist

        plen = len(path)
        if plen != 0:
            plen += 1
        files, folders = [], []
        for item in entries[1]:
            if item[2] == 'file':
                files.append(item[0][plen:])
            elif item[2] == 'directory':
                folders.append(item[0][plen:])

        return files, folders

    def file_contents(self, path, revision=None):
        tree = self._get_tree(revision)

        try:
            self._branch.lock_read()
            file_id = tree.path2id(path)
            if tree.kind(file_id) != 'file':
                # Django VCS expects file_contents to raise an exception on
                # directories, while bzrlib returns an empty string so check
                # explicitly, and raise an exception
                raise FileDoesNotExist
            out = tree.get_file(file_id).read()
            self._branch.unlock()
        except:
            raise FileDoesNotExist

        return out
