"""

util.py - Mercurial utility functions and platform specfic implementations

 Copyright 2005 K. Thananchayan <thananck@yahoo.com>

This software may be used and distributed according to the terms

of the GNU General Public License, incorporated herein by reference.

This contains helper routines that are independent of the SCM core and hide

platform-specific details from the core.

"""

import os, errno

from demandload import *

def binary(s):

    """return true if a string is binary data using diff's heuristic"""

    if s and '\0' in s[:4096]:

        return True

    return False

def unique(g):

    """return the uniq elements of iterable g"""

    seen = {}

    for f in g:

        if f not in seen:

            seen[f] = 1

            yield f

class Abort(Exception):

    """Raised if a command needs to print an error and exit."""

def always(fn): return True

def never(fn): return False

def globre(pat, head='^', tail='$'):

    "convert a glob pattern into a regexp"

    i, n = 0, len(pat)

    res = ''

    group = False

    def peek(): return i < n and pat[i]

    while i < n:

        c = pat[i]

        i = i+1

        if c == '*':

            if peek() == '*':

                i += 1

                res += '.*'

            else:

                res += '[^/]*'

        elif c == '?':

            res += '.'

        elif c == '[':

            j = i

            if j < n and pat[j] in '!]':

                j += 1

            while j < n and pat[j] != ']':

                j += 1

            if j >= n:

                res += '\\['

            else:

                stuff = pat[i:j].replace('\\','\\\\')

                i = j + 1

                if stuff[0] == '!':

                    stuff = '^' + stuff[1:]

                elif stuff[0] == '^':

                    stuff = '\\' + stuff

                res = '%s[%s]' % (res, stuff)

        elif c == '{':

            group = True

            res += '(?:'

        elif c == '}' and group:

            res += ')'

            group = False

        elif c == ',' and group:

            res += '|'

        else:

            res += re.escape(c)

    return head + res + tail

_globchars = {'[': 1, '{': 1, '*': 1, '?': 1}

def pathto(n1, n2):

    '''return the relative path from one place to another.

    this returns a path in the form used by the local filesystem, not hg.'''

    if not n1: return localpath(n2)

    a, b = n1.split('/'), n2.split('/')

    a.reverse(), b.reverse()

    while a and b and a[-1] == b[-1]:

        a.pop(), b.pop()

    b.reverse()

    return os.sep.join((['..'] * len(a)) + b)

def canonpath(root, cwd, myname):

    """return the canonical path of myname, given cwd and root"""

    rootsep = root + os.sep

    name = myname

    if not name.startswith(os.sep):

        name = os.path.join(root, cwd, name)

    name = os.path.normpath(name)

    if name.startswith(rootsep):

        return pconvert(name[len(rootsep):])

    elif name == root:

        return ''

    else:

        raise Abort('%s not under root' % myname)

def matcher(canonroot, cwd, names, inc, exc, head=''):

    """build a function to match a set of file patterns

    arguments:

    canonroot - the canonical root of the tree you're matching against

    cwd - the current working directory, if relevant

    names - patterns to find

    inc - patterns to include

    exc - patterns to exclude

    head - a regex to prepend to patterns to control whether a match is rooted

    a pattern is one of:

    're:<regex>'

    'glob:<shellglob>'

    'path:<explicit path>'

    'relpath:<relative path>'

    '<relative path>'

    returns:

    a 3-tuple containing

    - list of explicit non-pattern names passed in

    - a bool match(filename) function

    - a bool indicating if any patterns were passed in

    todo:

    make head regex a rooted bool

    """

    def patkind(name):

        for prefix in 're:', 'glob:', 'path:', 'relpath:':

            if name.startswith(prefix): return name.split(':', 1)

        for c in name:

            if c in _globchars: return 'glob', name

        return 'relpath', name

    def regex(kind, name, tail):

        '''convert a pattern into a regular expression'''

        if kind == 're':

            return name

        elif kind == 'path':

            return '^' + re.escape(name) + '(?:/|$)'

        elif kind == 'relpath':

            return head + re.escape(name) + tail

        return head + globre(name, '', tail)

    def matchfn(pats, tail):

        """build a matching function from a set of patterns"""

        if pats:

            pat = '(?:%s)' % '|'.join([regex(k, p, tail) for (k, p) in pats])

            return re.compile(pat).match

    def globprefix(pat):

        '''return the non-glob prefix of a path, e.g. foo/* -> foo'''

        root = []

        for p in pat.split(os.sep):

            if patkind(p)[0] == 'glob': break

            root.append(p)

        return '/'.join(root)

    pats = []

    files = []

    roots = []

    for kind, name in map(patkind, names):

        if kind in ('glob', 'relpath'):

            name = canonpath(canonroot, cwd, name)

            if name == '':

                kind, name = 'glob', '**'

        if kind in ('glob', 'path', 're'):

            pats.append((kind, name))

        if kind == 'glob':

            root = globprefix(name)

            if root: roots.append(root)

        elif kind == 'relpath':

            files.append((kind, name))

            roots.append(name)

    patmatch = matchfn(pats, '$') or always

    filematch = matchfn(files, '(?:/|$)') or always

    incmatch = always

    if inc:

        incmatch = matchfn(map(patkind, inc), '(?:/|$)')

    excmatch = lambda fn: False

    if exc:

        excmatch = matchfn(map(patkind, exc), '(?:/|$)')

    return (roots,

            lambda fn: (incmatch(fn) and not excmatch(fn) and

                        (fn.endswith('/') or

                         (not pats and not files) or

                         (pats and patmatch(fn)) or

                         (files and filematch(fn)))),

            (inc or exc or (pats and pats != [('glob', '**')])) and True)

def system(cmd, errprefix=None):

    """execute a shell command that must succeed"""

    rc = os.system(cmd)

    if rc:

        errmsg = "%s %s" % (os.path.basename(cmd.split(None, 1)[0]),

                            explain_exit(rc)[0])

        if errprefix:

            errmsg = "%s: %s" % (errprefix, errmsg)

        raise Abort(errmsg)

def rename(src, dst):

    """forcibly rename a file"""

    try:

        os.rename(src, dst)

    except:

        os.unlink(dst)

        os.rename(src, dst)

def copyfiles(src, dst, hardlink=None):

    """Copy a directory tree using hardlinks if possible"""

    if hardlink is None:

        hardlink = (os.stat(src).st_dev ==

                    os.stat(os.path.dirname(dst)).st_dev)

    if os.path.isdir(src):

        os.mkdir(dst)

        for name in os.listdir(src):

            srcname = os.path.join(src, name)

            dstname = os.path.join(dst, name)

            copyfiles(srcname, dstname, hardlink)

    else:

        if hardlink:

            try:

                os_link(src, dst)

            except:

                hardlink = False

                shutil.copy2(src, dst)

        else:

            shutil.copy2(src, dst)

def opener(base):

    """

    return a function that opens files relative to base

    this function is used to hide the details of COW semantics and

    remote file access from higher level code.

    """

    p = base

    def o(path, mode="r"):

        f = os.path.join(p, path)

        mode += "b" # for that other OS

        if mode[0] != "r":

            try:

                nlink = nlinks(f)

            except OSError:

                d = os.path.dirname(f)

                if not os.path.isdir(d):

                    os.makedirs(d)

            else:

                if nlink > 1:

                    file(f + ".tmp", "wb").write(file(f, "rb").read())

                    rename(f+".tmp", f)

        return file(f, mode)

    return o

def _makelock_file(info, pathname):

    ld = os.open(pathname, os.O_CREAT | os.O_WRONLY | os.O_EXCL)

    os.write(ld, info)

    os.close(ld)

def _readlock_file(pathname):

    return file(pathname).read()

def nlinks(pathname):

    """Return number of hardlinks for the given file."""

    return os.stat(pathname).st_nlink

if hasattr(os, 'link'):

    os_link = os.link

else:

    def os_link(src, dst):

        raise OSError(0, "Hardlinks not supported")

# Platform specific variants

if os.name == 'nt':

    nulldev = 'NUL:'

    try: # ActivePython can create hard links using win32file module

        import win32file

        def os_link(src, dst): # NB will only succeed on NTFS

            win32file.CreateHardLink(dst, src)

        def nlinks(pathname):

            """Return number of hardlinks for the given file."""

            try:

                fh = win32file.CreateFile(pathname,

                    win32file.GENERIC_READ, win32file.FILE_SHARE_READ,

                    None, win32file.OPEN_EXISTING, 0, None)

                res = win32file.GetFileInformationByHandle(fh)

                fh.Close()

                return res[7]

            except:

                return os.stat(pathname).st_nlink

    except ImportError:

        pass

    def is_exec(f, last):

        return last

    def set_exec(f, mode):

        pass

    def pconvert(path):

        return path.replace("\\", "/")

    def localpath(path):

        return path.replace('/', '\\')

    def normpath(path):

        return pconvert(os.path.normpath(path))

    makelock = _makelock_file

    readlock = _readlock_file

    def explain_exit(code):

        return "exited with status %d" % code, code

else:

    nulldev = '/dev/null'

    def is_exec(f, last):

        """check whether a file is executable"""

        return (os.stat(f).st_mode & 0100 != 0)

    def set_exec(f, mode):

        s = os.stat(f).st_mode

        if (s & 0100 != 0) == mode:

            return

        if mode:

            # Turn on +x for every +r bit when making a file executable

            # and obey umask.

            umask = os.umask(0)

            os.umask(umask)

            os.chmod(f, s | (s & 0444) >> 2 & ~umask)

        else:

            os.chmod(f, s & 0666)

    def pconvert(path):

        return path