# manifest.py - manifest revision class for mercurial
#
# Copyright 2005 Matt Mackall <mpm@selenic.com>
#
# This software may be used and distributed according to the terms
# of the GNU General Public License, incorporated herein by reference.

import struct
from revlog import *
from i18n import gettext as _
from demandload import *
demandload(globals(), "bisect array")

class manifest(revlog):
    def __init__(self, opener, local=True):
        self.mapcache = None
        self.listcache = None
        revlog.__init__(self, opener, "00manifest.i", "00manifest.d",
                        local=local)

    def read(self, node):
        if node == nullid: return {} # don't upset local cache
        if self.mapcache and self.mapcache[0] == node:
            return self.mapcache[1]
        text = self.revision(node)
        map = {}
        flag = {}
        self.listcache = array.array('c', text)
        lines = text.splitlines(1)
        for l in lines:
            (f, n) = l.split('\0')
            map[f] = bin(n[:40])
            flag[f] = (n[40:-1] == "x")
        self.mapcache = (node, map, flag)
        return map

    def readflags(self, node):
        if node == nullid: return {} # don't upset local cache
        if not self.mapcache or self.mapcache[0] != node:
            self.read(node)
        return self.mapcache[2]

    def diff(self, a, b):
        return mdiff.textdiff(str(a), str(b))

    def add(self, map, flags, transaction, link, p1=None, p2=None,
            changed=None):

        # returns a tuple (start, end).  If the string is found
        # m[start:end] are the line containing that string.  If start == end
        # the string was not found and they indicate the proper sorted 
        # insertion point.  This was taken from bisect_left, and modified
        # to find line start/end as it goes along.
        #
        # m should be a buffer or a string
        # s is a string
        #
        def manifestsearch(m, s, lo=0, hi=None):
            def advance(i, c):
                while i < lenm and m[i] != c:
                    i += 1
                return i
            lenm = len(m)
            if not hi:
                hi = lenm
            while lo < hi:
                mid = (lo + hi) // 2
                start = mid
                while start > 0 and m[start-1] != '\n':
                    start -= 1
                end = advance(start, '\0')
                if m[start:end] < s:
                    # we know that after the null there are 40 bytes of sha1
                    # this translates to the bisect lo = mid + 1
                    lo = advance(end + 40, '\n') + 1
                else:
                    # this translates to the bisect hi = mid
                    hi = start
            end = advance(lo, '\0')
            found = m[lo:end]
            if cmp(s, found) == 0: 
                # we know that after the null there are 40 bytes of sha1
                end = advance(end + 40, '\n')
                return (lo, end+1)
            else:
                return (lo, lo)

        # apply the changes collected during the bisect loop to our addlist
        # return a delta suitable for addrevision
        def addlistdelta(addlist, x):
            # start from the bottom up
            # so changes to the offsets don't mess things up.
            i = len(x)
            while i > 0:
                i -= 1
                start = x[i][0]
                end = x[i][1]
                if x[i][2]:
                    addlist[start:end] = array.array('c', x[i][2])
                else:
                    del addlist[start:end]
            return "".join([struct.pack(">lll", d[0], d[1], len(d[2])) + d[2] \
                            for d in x ])

        # if we're using the listcache, make sure it is valid and
        # parented by the same node we're diffing against
        if not changed or not self.listcache or not p1 or \
               self.mapcache[0] != p1:
            files = map.keys()
            files.sort()

            text = ["%s\000%s%s\n" %
                            (f, hex(map[f]), flags[f] and "x" or '')
                            for f in files]
            self.listcache = array.array('c', "".join(text))
            cachedelta = None
        else:
            addlist = self.listcache

            # combine the changed lists into one list for sorting
            work = [[x, 0] for x in changed[0]]
            work[len(work):] = [[x, 1] for x in changed[1]]
            work.sort()

            delta = []
            dstart = None
            dend = None
            dline = [""]
            start = 0
            # zero copy representation of addlist as a buffer
            addbuf = buffer(addlist)

            # start with a readonly loop that finds the offset of
            # each line and creates the deltas
            for w in work:
                f = w[0]
                # bs will either be the index of the item or the insert point
                start, end = manifestsearch(addbuf, f, start)
                if w[1] == 0:
                    l = "%s\000%s%s\n" % (f, hex(map[f]),
                                          flags[f] and "x" or '')
                else:
                    l = ""
                if start == end and w[1] == 1:
                    # item we want to delete was not found, error out
                    raise AssertionError(
                            _("failed to remove %s from manifest\n") % f)
                if dstart != None and dstart <= start and dend >= start:
                    if dend < end:
                        dend = end
                    if l:
                        dline.append(l)
                else:
                    if dstart != None:
                        delta.append([dstart, dend, "".join(dline)])
                    dstart = start
                    dend = end
                    dline = [l]

            if dstart != None:
                delta.append([dstart, dend, "".join(dline)])
            # apply the delta to the addlist, and get a delta for addrevision
            cachedelta = addlistdelta(addlist, delta)

            # the delta is only valid if we've been processing the tip revision
            if self.mapcache[0] != self.tip():
                cachedelta = None
            self.listcache = addlist

        n = self.addrevision(buffer(self.listcache), transaction, link, p1,  \
                             p2, cachedelta)
        self.mapcache = (n, map, flags)

        return n