"""
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 *
demandload(globals(), "re")

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 copytree(src, dst, copyfile):
    """Copy a directory tree, files are copied using 'copyfile'."""
    names = os.listdir(src)
    os.mkdir(dst)

    for name in names:
        srcname = os.path.join(src, name)
        dstname = os.path.join(dst, name)
        if os.path.isdir(srcname):
            copytree(srcname, dstname, copyfile)
        elif os.path.isfile(srcname):
            copyfile(srcname, dstname)
        else:
            pass

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()

# Platform specific variants
if os.name == 'nt':
    nulldev = 'NUL:'

    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

    def localpath(path):
        return path

    normpath = os.path.normpath

    def makelock(info, pathname):
        try:
            os.symlink(info, pathname)
        except OSError, why:
            if why.errno == errno.EEXIST:
                raise
            else:
                _makelock_file(info, pathname)

    def readlock(pathname):
        try:
            return os.readlink(pathname)
        except OSError, why:
            if why.errno == errno.EINVAL:
                return _readlock_file(pathname)
            else:
                raise

    def explain_exit(code):
        """return a 2-tuple (desc, code) describing a process's status"""
        if os.name == 'nt': # os.WIFxx is not supported on windows
            return "aborted with error." , -1
        if os.WIFEXITED(code):
            val = os.WEXITSTATUS(code)
            return "exited with status %d" % val, val
        elif os.WIFSIGNALED(code):
            val = os.WTERMSIG(code)
            return "killed by signal %d" % val, val
        elif os.WIFSTOPPED(code):
            val = os.WSTOPSIG(code)
            return "stopped by signal %d" % val, val
        raise ValueError("invalid exit code")