#!/usr/bin/env python

##############################################################################
# Quick Intro:
# 1) Create '.wot' in your home directory. Fill it with public keys from 'wot'.
# 2) Create '.seals' in your home directory. Place all signatures there from 'sigs'.
# 3) Create a 'patches' directory somewhere where 'v' can find it. Or use this one.
# 4) ./v.py patches command
# e.g.,
# ./v.py patches w
#                  ^^ displays WoT
#  ./v.py patches p patches/asciilifeform_add_verifyall_option.vpatch asciis_bleedingedge
#                  ^^ this 'presses' (creates the actual tree)
#                  ^^ approximately like a 'checkout' in your vanilla flavoured shithub.

##############################################################################

import os, sys, shutil, argparse, re, tempfile, gnupg, subprocess

##############################################################################
vver = 98 # This program's Kelvin version.

## HOW YOU CAN HELP: ##

# * TESTS plox, ty!
#
# Report findings in #bitcoin-assets on Freenode.

##############################################################################

prolog =  '''\
(C) 2015 NoSuchlAbs.
You do not have, nor can you ever acquire the right to use, copy or distribute
this software ; Should you use this software for any purpose, or copy and
distribute it to anyone or in any manner, you are breaking the laws of whatever
soi-disant jurisdiction, and you promise to continue doing so for the indefinite
future. In any case, please always : read and understand any software ;
verify any PGP signatures that you use - for any purpose.
'''

intro = "V (ver. {0}K)\n".format(vver)

##############################################################################
def toposort(unsorted):
    sorted = []
    unsorted = dict(unsorted)
    while unsorted:
        acyclic = False
        for node, edges in unsorted.items():
            for edge in edges:
                if edge in unsorted:
                    break
            else:
                acyclic = True
                del unsorted[node]
                sorted.append((node, edges))
        if not acyclic:
            fatal("Cyclic graph!")
    return sorted
##############################################################################

vpatch_path = "vpatch"
verbose = False

def fatal(msg):
    sys.stderr.write(msg + "\n")
    exit(1)

def spew(msg):
    if verbose:
        print msg

# List of files in a directory, in lexical order.
def dir_files(dir):
    return sorted([os.path.join(dir, fn) for fn in next(os.walk(dir))[2]])

# GPG is retarded and insists on 'keychain.'
# This will be a temp dir, because we don't do any crypto.
gpgtmp = tempfile.mkdtemp()
gpg = gnupg.GPG(gnupghome=gpgtmp)
gpg.encoding = 'utf-8'

# Known WoT public keys.
pubkeys = {}

# The subset of vpatches that are considered valid.
patches = []

# Banners (i.e. vpatches mapped to their guarantors)
banners = {}

# Roots (i.e. vpatches parented by thin air)
roots = []

# Table mapping file hash to originating vpatch
desc = {}
desc['false'] = 'false'


# Grep for diff magics, and memoize
def vpdata(path, exp, cache):
    l = cache.get(path)
    if not l:
        l = []
        patch = open(path, 'r').read()
        for m in re.findall(exp, patch, re.MULTILINE):
            l += [{'p':m[0], 'h':m[1]}]
        cache[path] = l
    return l

# Get parents of a vpatch
pcache = {}
def parents(vpatch):
    parents = vpdata(vpatch, r'^--- (\S+) (\S+)$', pcache)
    if not parents:
        fatal("{0} is INVALID, check whether it IS a vpatch!".format(vpatch))
    return parents

# Get children of a vpatch
ccache = {}
def children(vpatch):
    children = vpdata(vpatch, r'^\+\+\+ (\S+) (\S+)$', ccache)
    if not children:
        fatal("{0} is INVALID, check whether it IS a vpatch!".format(vpatch))
    # Record descendents:
    for child in children:
        h = child['h']
        if h != 'false':
            desc[h] = vpatch
    return children

# It is entirely possible to have more than one root!
# ... exactly how, is left as an exercise for readers.
def find_roots(patchset):
    rset = []
    # Walk, find roots
    for p in patchset:
        if all(p['h'] == 'false' for p in parents(p)):
            rset += [p]
            spew("Found a Root: '{0}'".format(p))
    return rset

# Get antecedents.
def get_ante(vpatch):
    ante = {}
    for p in parents(vpatch):
        pp = desc.get(p['h']) # Patch where this appears
        if not ante.get(pp):
            ante[pp] = []
        ante[pp] += [p['p']]
    return ante

# Get descendants.
def get_desc(vpatch):
    des = {}
    for p in patches:
        ante = get_ante(p)
        if vpatch in ante.keys():
            des[p] = ante[vpatch]
    return des

##############################################################################

# Print name of patch and its guarantors, or 'WILD' if none known.
def disp_vp(vpatch):
    seals = ', '.join(map(str, banners[vpatch]))
    if seals == '':
        seals = 'WILD'
    return "{0} ({1})".format(vpatch, seals)

##############################################################################

# Command: WoT
def c_wot(args):
    for k in pubkeys.values():
        print "{0}:{1} ({2})".format(k['handle'], k['fp'], k['id'])

# Command: Flow
def c_flow(args):
    for p in patches:
        print disp_vp(p)

# Command: Roots.
def c_roots(args):
    for r in roots:
        print "Root: " + disp_vp(r)

# Command: Antecedents.
def c_ante(args):
    ante = get_ante(args.query)
    for p in ante.keys():
        if p != 'false':
            print "{0} [{1}]".format(disp_vp(p), '; '.join(map(str, ante[p])))

# Command: Descendants
def c_desc(args):
    des = get_desc(args.query)
    for d in des.keys():
        print "Descendant: {0} [{1}]".format(disp_vp(d), '; '.join(map(str, des[d])))

# Command: Press.
def c_press(args):
    print "Pressing using head: {0} to path: '{1}'".format(args.head, args.dest)
    headpos = patches.index(args.head)
    seq = patches[:headpos + 1]
    if os.path.exists(args.dest):
        print "Warning: target {0} already exists".format(args.dest)
    else:
        os.mkdir(args.dest)
    for p in seq:
        print "Using: {0}".format(disp_vp(p))
        out = subprocess.Popen([vpatch_path], cwd=args.dest, stdin=subprocess.PIPE,
                               stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        with open(p, "r") as inp:
            body = inp.read()
        stdout, stderr = out.communicate(body)
        print stdout,
        if out.returncode != 0:
            fatal(("-----------------------------------\n" +
                   "There was an error while pressing:\n" +
                   "{0}\n" +
                   "Result in {1} might be in an invalid state!\n" +
                   "-----------------------------------").format(stderr.strip(), args.dest))
    print "Completed Pressing using head: {0} to path: '{1}'".format(args.head, args.dest)

# Command: Origin.
def c_origin(args):
    o = desc.get(args.query)
    if o:
        print disp_vp(o)
    else:
        print "No origin known."

##############################################################################

##############################################################################
# Command line parameter processor.
parser = argparse.ArgumentParser(description=intro, epilog=prolog)

# Print paths, etc
parser.add_argument('-v', dest='verbose', default=False,
                    action="store_true", help='Verbose.')

# Permit the use of patches no one has yet sealed. Use this ONLY for own dev work!
parser.add_argument('-wild', dest='wild', default=False,
                    action="store_true", help='Permit wild (UNSEALED!) vpatches.')

# Glom keyid (short fingerprint) onto every WoT handle.
parser.add_argument('-fingers', dest='fingers', default=False,
                    action="store_true", help='Prefix keyid to all WoT handles.')

# Default path of WoT public keys is /home/yourusername/.wot
# This dir must exist. Alternatively, you may specify another.
parser.add_argument('--wot', dest='wot', default=os.path.join(os.path.expanduser('~'), '.wot'),
                    action="store", help='Use WoT in given directory. (Default: ~/.wot)')

# Default path of the seals (PGP signatures) is /home/yourusername/.seals
# This dir must exist. Alternatively, you may specify another.
parser.add_argument('--seals', dest='seals', default=os.path.join(os.path.expanduser('~'), '.seals'),
                    action="store", help='Use Seals in given directory. (Default: ~/.seals)')

# REQUIRED: Path of directory with vpatches.
parser.add_argument('vpatches', help='Vpatch directory to operate on. [REQUIRED]')

# REQUIRED: Command.
subparsers = parser.add_subparsers(help='Command [REQUIRED]')

parser_w = subparsers.add_parser('w', help='Display WoT.')
parser_w.set_defaults(f=c_wot)

parser_r = subparsers.add_parser('r', help='Display Roots.')
parser_r.set_defaults(f=c_roots)

parser_a = subparsers.add_parser('a', help='Display Antecedents [PATCH]')
parser_a.set_defaults(f=c_ante)
parser_a.add_argument('query', action="store", help='Patch.')

parser_d = subparsers.add_parser('d', help='Display Descendants [PATCH]')
parser_d.set_defaults(f=c_desc)
parser_d.add_argument('query', action="store", help='Patch.')

parser_l = subparsers.add_parser('f', help='Compute Flow.')
parser_l.set_defaults(f=c_flow)

parser_p = subparsers.add_parser('p', help='Press [HEADPATCH AND DESTINATION]')
parser_p.set_defaults(f=c_press)
parser_p.add_argument('head', action="store", help='Head patch.')
parser_p.add_argument('dest', action="store", help='Destionation directory.')

parser_o = subparsers.add_parser('o', help='Find Origin [SHA512]')
parser_o.set_defaults(f=c_origin)
parser_o.add_argument('query', action="store", help='SHA512 to search for.')


##############################################################################

# V cannot operate without vpatches, WoT, and Seals datasets.
def reqdir(path):
    if (not (os.path.isdir(path))):
        fatal("Directory '{0}' does not exist!".format(path))
    return path


def main():
    global verbose, pubkeys, patches, roots, banners

    args = parser.parse_args()
    verbose = args.verbose

    # Patch and Sigs dirs
    pdir = reqdir(args.vpatches)
    sdir = reqdir(args.seals)
    wdir = reqdir(args.wot)

    spew("Using patches from:" + pdir)
    spew("Using signatures from:" + sdir)
    spew("Using wot from:" + wdir)

    pfiles = dir_files(pdir)
    sfiles = dir_files(sdir)
    wfiles = dir_files(wdir)

    # Build WoT from pubkeys
    handle = {}
    for w in wfiles:
        pubkey = open(w, 'r').read()
        impkey = gpg.import_keys(pubkey)
        for fp in impkey.fingerprints:
            handle[fp] = os.path.splitext(os.path.basename(w))[0]

    for k in gpg.list_keys():
        name = handle[k['fingerprint']]
        if args.fingers:
            name += '-' + k['keyid']
        uids = ', '.join(map(str, k['uids']))
        pubkeys[k['keyid']] = {'fp':k['fingerprint'],
                               'id':uids,
                               'handle':name}
        for subkey in k.get('subkeys', []):
            keyid, fingerprint = subkey[0], subkey[2]
            pubkeys[keyid] = {'fp':fingerprint,
                              'id':uids,
                              'handle':name}

    # Validate seals
    for p in pfiles:
        pt = os.path.basename(p)
        banners[p] = []
        for s in sfiles:
            sig = os.path.basename(s)
            # All seals must take the form patchtitle.vpatch.yourname.sig
            if sig.find(pt) == 0: # substring of sig filename up through '.vpatch'
                v = gpg.verify_file(open(s, 'r'), data_filename=p)
                if v.valid:
                    banners[p] += [pubkeys[v.key_id]['handle']]
                else:
                    fatal("---------------------------------------------------------------------\n" +
                          "WARNING: {0} is an INVALID seal for {1} !\n".format(sig, pt) +
                          "Check that this user is in your WoT, and that this key has not expired.\n" +
                          "Otherwise remove the invalid seal from your SEALS directory.\n" +
                          "---------------------------------------------------------------------")

    # Select the subset of vpatches currently in use.
    for p in pfiles:
        if banners.get(p) or args.wild:
            patches += [p]
            children(p) # Memoize.
            parents(p) # Memoize.

    roots = find_roots(patches)
    if not roots:
        fatal('No roots found!')

    # Topological ordering of flow graph
    l = []
    for p in patches:
        l += [(p, get_desc(p).keys())]
    s = map(lambda x:x[0], toposort(l))
    patches = s[::-1]

    # Run command
    args.f(args)

    # Remove temporary keychain
    shutil.rmtree(gpgtmp)

##############################################################################

if __name__ == '__main__' :
    main()

##############################################################################