""" This extension provides direct access
It is the ability to refer and access hidden sha in commands provided that you 
know their value.
For example hg log -r xxx where xxx is a commit has should work whether xxx is
hidden or not as we assume that the user knows what he is doing when referring
to xxx.
"""
from mercurial import extensions
from mercurial import cmdutil
from mercurial import repoview
from mercurial import branchmap
from mercurial import revset
from mercurial import error
from mercurial import commands
from mercurial.i18n import _

cmdtable = {}
command = cmdutil.command(cmdtable)

# List of commands where no warning is shown for direct access
directaccesslevel = [
    # warning or not, extension (None if core), command name
    (False, None, 'update'), 
    (False, None, 'export'),
    (True,  'rebase', 'rebase'),
    (False,  'evolve', 'prune'),
]

def reposetup(ui, repo):
    repo._explicitaccess = set()

def _computehidden(repo):
    hidden = repoview.computehidden(repo)
    cl = repo.changelog
    dynamic = hidden & repo._explicitaccess
    if dynamic:
        blocked = cl.ancestors(dynamic, inclusive=True)
        hidden = frozenset(r for r in hidden if r not in blocked)
    return hidden

def setupdirectaccess():
    """ Add two new filtername that behave like visible to provide direct access
    and direct access with warning. Wraps the commands to setup direct access """
    repoview.filtertable.update({'visible-directaccess-nowarn': _computehidden})
    repoview.filtertable.update({'visible-directaccess-warn': _computehidden})
    branchmap.subsettable['visible-directaccess-nowarn'] = 'visible'
    branchmap.subsettable['visible-directaccess-warn'] = 'visible'

    for warn, ext, cmd in directaccesslevel:
        cmdtable = extensions.find(ext).cmdtable if ext else commands.table
        wrapper = wrapwithwarning if warn else wrapwithoutwarning
        try:
            extensions.wrapcommand(cmdtable, cmd, wrapper)
        except error.UnknownCommand:
            pass

def wrapwithoutwarning(orig, ui, repo, *args, **kwargs):
    if repo and repo.filtername == 'visible':
        repo = repo.filtered("visible-directaccess-nowarn")
    return orig(ui, repo, *args, **kwargs)

def wrapwithwarning(orig, ui, repo, *args, **kwargs):
    if repo and repo.filtername == 'visible':
        repo = repo.filtered("visible-directaccess-warn")
    return orig(ui, repo, *args, **kwargs)

def extsetup(ui):
    extensions.wrapfunction(revset, 'posttreebuilthook', _posttreebuilthook)
    setupdirectaccess()

def gethashsymbols(tree):
    # Returns the list of symbols of the tree that look like hashes
    # for example for the revset 3::abe3ff it will return ('abe3ff')
    if not tree:
        return []

    if len(tree) == 2 and tree[0] == "symbol":
        try:
            int(tree[1])
            return []
        except ValueError as e:
            return [tree[1]]
    elif len(tree) == 3:
        return gethashsymbols(tree[1]) + gethashsymbols(tree[2])
    else:
        return []

def _posttreebuilthook(orig, tree, repo):
    # This is use to enabled direct hash access
    # We extract the symbols that look like hashes and add them to the
    # explicitaccess set
    orig(tree, repo)
    filternm = ""
    if repo is not None:
        filternm = repo.filtername
    if filternm is not None and filternm.startswith('visible-directaccess'):
        prelength = len(repo._explicitaccess)
        accessbefore = set(repo._explicitaccess)
        repo.symbols = gethashsymbols(tree)
        cl = repo.unfiltered().changelog
        for node in repo.symbols:
            try:
                node = cl._partialmatch(node)
            except error.LookupError:
                node = None
            if node is not None:
                rev = cl.rev(node)
                if rev not in repo.changelog:
                    repo._explicitaccess.add(rev)
        if prelength != len(repo._explicitaccess):
            if repo.filtername != 'visible-directaccess-nowarn':
                unhiddencommits = repo._explicitaccess - accessbefore
                repo.ui.warn( _("Warning: accessing hidden changesets %s " 
                                "for write operation\n") % 
                                (",".join([str(repo.unfiltered()[l]) 
                                    for l in unhiddencommits])))
            repo.invalidatevolatilesets()