# filemerge.py - file-level merge handling for Mercurial

#

# Copyright 2006, 2007, 2008 Matt Mackall <mpm@selenic.com>

#

# This software may be used and distributed according to the terms of the

# GNU General Public License version 2 or any later version.

from __future__ import absolute_import

import filecmp

import os

import re

import tempfile

from .i18n import _

from .node import nullid, short

from . import (

    cmdutil,

    error,

    match,

    simplemerge,

    tagmerge,

    templatekw,

    templater,

    util,

)

def _toolstr(ui, tool, part, default=""):

    return ui.config("merge-tools", tool + "." + part, default)

def _toolbool(ui, tool, part, default=False):

    return ui.configbool("merge-tools", tool + "." + part, default)

def _toollist(ui, tool, part, default=[]):

    return ui.configlist("merge-tools", tool + "." + part, default)

internals = {}

# Merge tools to document.

internalsdoc = {}

# internal tool merge types

nomerge = None

mergeonly = 'mergeonly'  # just the full merge, no premerge

fullmerge = 'fullmerge'  # both premerge and merge

class absentfilectx(object):

    """Represents a file that's ostensibly in a context but is actually not

    present in it.

    This is here because it's very specific to the filemerge code for now --

    other code is likely going to break with the values this returns."""

    def __init__(self, ctx, f):

        self._ctx = ctx

        self._f = f

    def path(self):

        return self._f

    def size(self):

        return None

    def data(self):

        return None

    def filenode(self):

        return nullid

    _customcmp = True

    def cmp(self, fctx):

        """compare with other file context

        returns True if different from fctx.

        """

        return not (fctx.isabsent() and

                    fctx.ctx() == self.ctx() and

                    fctx.path() == self.path())

    def flags(self):

        return ''

    def changectx(self):

        return self._ctx

    def isbinary(self):

        return False

    def isabsent(self):

        return True

def internaltool(name, mergetype, onfailure=None, precheck=None):

    '''return a decorator for populating internal merge tool table'''

    def decorator(func):

        fullname = ':' + name

        func.__doc__ = "``%s``\n" % fullname + func.__doc__.strip()

        internals[fullname] = func

        internals['internal:' + name] = func

        internalsdoc[fullname] = func

        func.mergetype = mergetype

        func.onfailure = onfailure

        func.precheck = precheck

        return func

    return decorator

def _findtool(ui, tool):

    if tool in internals:

        return tool

    return findexternaltool(ui, tool)

def findexternaltool(ui, tool):

    for kn in ("regkey", "regkeyalt"):

        k = _toolstr(ui, tool, kn)

        if not k:

            continue

        p = util.lookupreg(k, _toolstr(ui, tool, "regname"))

        if p:

            p = util.findexe(p + _toolstr(ui, tool, "regappend"))

            if p:

                return p

    exe = _toolstr(ui, tool, "executable", tool)

    return util.findexe(util.expandpath(exe))

def _picktool(repo, ui, path, binary, symlink, changedelete):

    def supportscd(tool):

        return tool in internals and internals[tool].mergetype == nomerge

    def check(tool, pat, symlink, binary, changedelete):

        tmsg = tool

        if pat:

            tmsg += " specified for " + pat

        if not _findtool(ui, tool):

            if pat: # explicitly requested tool deserves a warning

                ui.warn(_("couldn't find merge tool %s\n") % tmsg)

            else: # configured but non-existing tools are more silent

                ui.note(_("couldn't find merge tool %s\n") % tmsg)

        elif symlink and not _toolbool(ui, tool, "symlink"):

            ui.warn(_("tool %s can't handle symlinks\n") % tmsg)

        elif binary and not _toolbool(ui, tool, "binary"):

            ui.warn(_("tool %s can't handle binary\n") % tmsg)

        elif changedelete and not supportscd(tool):

            # the nomerge tools are the only tools that support change/delete

            # conflicts

            pass

        elif not util.gui() and _toolbool(ui, tool, "gui"):

            ui.warn(_("tool %s requires a GUI\n") % tmsg)

        else:

            return True

        return False

    # internal config: ui.forcemerge

    # forcemerge comes from command line arguments, highest priority

    force = ui.config('ui', 'forcemerge')

    if force:

        toolpath = _findtool(ui, force)

        if changedelete and not supportscd(toolpath):

            return ":prompt", None

        else:

            if toolpath:

                return (force, util.shellquote(toolpath))

            else:

                # mimic HGMERGE if given tool not found

                return (force, force)

    # HGMERGE takes next precedence

    hgmerge = os.environ.get("HGMERGE")

    if hgmerge:

        if changedelete and not supportscd(hgmerge):

            return ":prompt", None

        else:

            return (hgmerge, hgmerge)

    # then patterns

    for pat, tool in ui.configitems("merge-patterns"):

        mf = match.match(repo.root, '', [pat])

        if mf(path) and check(tool, pat, symlink, False, changedelete):

            toolpath = _findtool(ui, tool)

            return (tool, util.shellquote(toolpath))

    # then merge tools

    tools = {}

    disabled = set()

    for k, v in ui.configitems("merge-tools"):

        t = k.split('.')[0]

        if t not in tools:

            tools[t] = int(_toolstr(ui, t, "priority", "0"))

        if _toolbool(ui, t, "disabled", False):

            disabled.add(t)

    names = tools.keys()

    tools = sorted([(-p, t) for t, p in tools.items() if t not in disabled])

    uimerge = ui.config("ui", "merge")

    if uimerge:

        # external tools defined in uimerge won't be able to handle

        # change/delete conflicts

        if uimerge not in names and not changedelete:

            return (uimerge, uimerge)

        tools.insert(0, (None, uimerge)) # highest priority

    tools.append((None, "hgmerge")) # the old default, if found

    for p, t in tools:

        if check(t, None, symlink, binary, changedelete):

            toolpath = _findtool(ui, t)

            return (t, util.shellquote(toolpath))

    # internal merge or prompt as last resort

    if symlink or binary or changedelete:

        return ":prompt", None

    return ":merge", None

def _eoltype(data):

    "Guess the EOL type of a file"

    if '\0' in data: # binary

        return None

    if '\r\n' in data: # Windows

        return '\r\n'

    if '\r' in data: # Old Mac

        return '\r'

    if '\n' in data: # UNIX

        return '\n'

    return None # unknown

def _matcheol(file, origfile):

    "Convert EOL markers in a file to match origfile"

    tostyle = _eoltype(util.readfile(origfile))

    if tostyle:

        data = util.readfile(file)

        style = _eoltype(data)

        if style:

            newdata = data.replace(style, tostyle)

            if newdata != data:

                util.writefile(file, newdata)

@internaltool('prompt', nomerge)

def _iprompt(repo, mynode, orig, fcd, fco, fca, toolconf):

    """Asks the user which of the local or the other version to keep as

    the merged version."""

    ui = repo.ui

    fd = fcd.path()

    try:

        if fco.isabsent():

            index = ui.promptchoice(

                _("local changed %s which remote deleted\n"

                  "use (c)hanged version or (d)elete?"

                  "$$ &Changed $$ &Delete") % fd, 0)

            choice = ['local', 'other'][index]

        elif fcd.isabsent():

            index = ui.promptchoice(

                _("remote changed %s which local deleted\n"

                  "use (c)hanged version or leave (d)eleted?"

                  "$$ &Changed $$ &Deleted") % fd, 0)

            choice = ['other', 'local'][index]

        else:

            index = ui.promptchoice(_("no tool found to merge %s\n"

                                      "keep (l)ocal or take (o)ther?"

                                      "$$ &Local $$ &Other") % fd, 0)

            choice = ['local', 'other'][index]

        if choice == 'other':

            return _iother(repo, mynode, orig, fcd, fco, fca, toolconf)

        else:

            return _ilocal(repo, mynode, orig, fcd, fco, fca, toolconf)

    except error.ResponseExpected:

        ui.write("\n")

        return 1, False

@internaltool('local', nomerge)

def _ilocal(repo, mynode, orig, fcd, fco, fca, toolconf):

    """Uses the local version of files as the merged version."""

    return 0, fcd.isabsent()

@internaltool('other', nomerge)

def _iother(repo, mynode, orig, fcd, fco, fca, toolconf):

    """Uses the other version of files as the merged version."""

    if fco.isabsent():

        # local changed, remote deleted -- 'deleted' picked

        repo.wvfs.unlinkpath(fcd.path())

        deleted = True

    else:

        repo.wwrite(fcd.path(), fco.data(), fco.flags())

        deleted = False

    return 0, deleted

@internaltool('fail', nomerge)

def _ifail(repo, mynode, orig, fcd, fco, fca, toolconf):

    """

    Rather than attempting to merge files that were modified on both

    branches, it marks them as unresolved. The resolve command must be

    used to resolve these conflicts."""

    return 1, False

def _premerge(repo, toolconf, files, labels=None):

    tool, toolpath, binary, symlink = toolconf

    if symlink:

        return 1

    a, b, c, back = files

    ui = repo.ui

    validkeep = ['keep', 'keep-merge3']

    # do we attempt to simplemerge first?

    try:

        premerge = _toolbool(ui, tool, "premerge", not binary)

    except error.ConfigError:

        premerge = _toolstr(ui, tool, "premerge").lower()

        if premerge not in validkeep:

            _valid = ', '.join(["'" + v + "'" for v in validkeep])

            raise error.ConfigError(_("%s.premerge not valid "

                                      "('%s' is neither boolean nor %s)") %

                                    (tool, premerge, _valid))

    if premerge:

        if premerge == 'keep-merge3':

            if not labels:

                labels = _defaultconflictlabels

            if len(labels) < 3:

                labels.append('base')

        r = simplemerge.simplemerge(ui, a, b, c, quiet=True, label=labels)

        if not r:

            ui.debug(" premerge successful\n")

            return 0

        if premerge not in validkeep:

            util.copyfile(back, a) # restore from backup and try again

    return 1 # continue merging

def _mergecheck(repo, mynode, orig, fcd, fco, fca, toolconf):

    tool, toolpath, binary, symlink = toolconf

    if symlink:

        repo.ui.warn(_('warning: internal %s cannot merge symlinks '

                       'for %s\n') % (tool, fcd.path()))

        return False

    return True

def _merge(repo, mynode, orig, fcd, fco, fca, toolconf, files, labels, mode):

    """

    Uses the internal non-interactive simple merge algorithm for merging

    files. It will fail if there are any conflicts and leave markers in

    the partially merged file. Markers will have two sections, one for each side

    of merge, unless mode equals 'union' which suppresses the markers."""

    a, b, c, back = files

    ui = repo.ui

    r = simplemerge.simplemerge(ui, a, b, c, label=labels, mode=mode)

    return True, r, False

@internaltool('union', fullmerge,

              _("warning: conflicts while merging %s! "

                "(edit, then use 'hg resolve --mark')\n"),

              precheck=_mergecheck)

def _iunion(repo, mynode, orig, fcd, fco, fca, toolconf, files, labels=None):

    """

    Uses the internal non-interactive simple merge algorithm for merging

    files. It will use both left and right sides for conflict regions.

    No markers are inserted."""

    return _merge(repo, mynode, orig, fcd, fco, fca, toolconf,

                  files, labels, 'union')

@internaltool('merge', fullmerge,

              _("warning: conflicts while merging %s! "

                "(edit, then use 'hg resolve --mark')\n"),

              precheck=_mergecheck)