# Copyright (c) 2015, NORDUnet A/S.
# See LICENSE for licensing information.

import os
import base64
import hashlib
import sys
import struct
import json
import yaml
import argparse
import requests
import time
import fcntl
import errno
import multiprocessing
import logging
try:
    import permdb
except ImportError:
    pass
from certtools import get_leaf_hash, http_request

def parselogrow(row):
    return base64.b16decode(row, casefold=True)

def get_logorder(filename, items=-1):
    logorder = []
    n = 0
    for row in open(filename, "r"):
        if n == items:
            break
        logorder.append(parselogrow(row.rstrip()))
        n += 1
    return logorder

def get_nfetched(currentsizefile, logorderfile):
    try:
        limit = json.loads(open(currentsizefile).read())
    except (IOError, ValueError):
        return 0
    if limit['index'] >= 0:
        with open(logorderfile, 'r') as f:
            f.seek(limit['index']*65)
            assert f.read(64).lower() == limit['hash']
    return limit['index'] + 1

def get_sth(filename):
    try:
        sth = json.loads(open(filename, 'r').read())
    except (IOError, ValueError):
        sth = {'tree_size': -1,
               'timestamp': 0,
               'sha256_root_hash': '',
               'tree_head_signature': ''}
    return sth

def read_chain_open(chainsdir, filename):
    path = chainsdir + "/" + \
      filename[0:2] + "/" + filename[2:4] + "/" + filename[4:6]
    f = open(path + "/" + filename, "r")
    return f

def read_chain(chainsdir, key):
    filename = base64.b16encode(key).upper()
    try:
        f = read_chain_open(chainsdir, filename)
    except IOError:
        f = read_chain_open(chainsdir, filename.lower())
    value = f.read()
    f.close()
    return value

def tlv_decode(data):
    (length,) = struct.unpack(">I", data[0:4])
    dtype = data[4:8]
    value = data[8:length]
    rest = data[length:]
    return (dtype, value, rest)

def tlv_encode(dtype, value):
    assert len(dtype) == 4
    data = struct.pack(">I", len(value) + 8) + dtype + value
    return data

def tlv_decodelist(data):
    l = []
    while len(data):
        (dtype, value, rest) = tlv_decode(data)
        l.append((dtype, value))
        data = rest
    return l

def tlv_encodelist(l):
    data = ""
    for (dtype, value) in l:
        data += tlv_encode(dtype, value)
    return data

def unwrap_entry(entry):
    ploplevel = tlv_decodelist(entry)
    assert len(ploplevel) == 2
    (ploptype, plopdata) = ploplevel[0]
    (plopchecksumtype, plopchecksum) = ploplevel[1]
    assert ploptype == "PLOP"
    assert plopchecksumtype == "S256"
    computedchecksum = hashlib.sha256(plopdata).digest()
    assert computedchecksum == plopchecksum
    return plopdata

def wrap_entry(entry):
    return tlv_encodelist([("PLOP", entry),
                           ("S256", hashlib.sha256(entry).digest())])

def verify_entry(verifycert, entry, ehash):
    packed = unwrap_entry(entry)
    unpacked = tlv_decodelist(packed)
    (mtltype, mtl) = unpacked[0]
    assert ehash == get_leaf_hash(mtl)
    assert mtltype == "MTL1"
    s = struct.pack(">I", len(packed)) + packed
    try:
        verifycert.stdin.write(s)
    except IOError:
        sys.stderr.write("merge: unable to write to verifycert process: ")
        while 1:
            line = verifycert.stdout.readline()
            if line:
                sys.stderr.write(line)
            else:
                sys.exit(1)
    result_length_packed = verifycert.stdout.read(4)
    (result_length,) = struct.unpack(">I", result_length_packed)
    result = verifycert.stdout.read(result_length)
    assert len(result) == result_length
    (error_code,) = struct.unpack("B", result[0:1])
    if error_code != 0:
        print >>sys.stderr, result[1:]
        sys.exit(1)

def hexencode(key):
    return base64.b16encode(key).lower()

def hexdecode(s):
    return base64.b16decode(s.upper())

def write_chain(key, value, chainsdir, hashed_dir=True):
    filename = hexencode(key)
    if hashed_dir:
        path = chainsdir + "/" \
          + filename[0:2] + "/" + filename[2:4] + "/" + filename[4:6]
        try:
            os.makedirs(path)
        except Exception:
            pass
    else:
        path = chainsdir
    f = open(path + "/" + filename, "w")
    f.write(value)
    f.close()

def add_to_logorder(logorderfile, key):
    f = open(logorderfile, "a")
    f.write(hexencode(key) + "\n")
    f.close()

def fsync_logorder(logorderfile):
    f = open(logorderfile, "a")
    os.fsync(f.fileno())
    f.close()

def get_new_entries(node, baseurl, own_key, paths):
    try:
        result = http_request(baseurl + "plop/v1/storage/fetchnewentries",
                              key=own_key, verifynode=node,
                              publickeydir=paths["publickeys"])
        parsed_result = json.loads(result)
        if parsed_result.get(u"result") == u"ok":
            return [base64.b64decode(entry) for \
                    entry in parsed_result[u"entries"]]
        print >>sys.stderr, "ERROR: fetchnewentries", parsed_result
        sys.exit(1)
    except requests.exceptions.HTTPError, e:
        print >>sys.stderr, "ERROR: fetchnewentries", e.response
        sys.exit(1)

def get_entries(node, baseurl, own_key, paths, hashes):
    try:
        params = {"hash":[base64.b64encode(ehash) for ehash in hashes]}
        result = http_request(baseurl + "plop/v1/storage/getentry",
                              params=params,
                              key=own_key, verifynode=node,
                              publickeydir=paths["publickeys"])
        parsed_result = json.loads(result)
        if parsed_result.get(u"result") == u"ok":
            entries = dict([(base64.b64decode(entry["hash"]),
                             base64.b64decode(entry["entry"])) for \
                             entry in parsed_result[u"entries"]])
            assert len(entries) == len(hashes)
            assert set(entries.keys()) == set(hashes)
            return entries
        print >>sys.stderr, "ERROR: getentry", parsed_result
        sys.exit(1)
    except requests.exceptions.HTTPError, e:
        print >>sys.stderr, "ERROR: getentry", e.request.url, e.response
        sys.exit(1)

def get_curpos(node, baseurl, own_key, paths):
    try:
        result = http_request(baseurl + "plop/v1/frontend/currentposition",
                              key=own_key, verifynode=node,
                              publickeydir=paths["publickeys"])
        parsed_result = json.loads(result)
        if parsed_result.get(u"result") == u"ok":
            return True, parsed_result[u"position"]
        return False, parsed_result
    except requests.exceptions.HTTPError, e:
        return False, e.response

def get_verifiedsize(node, baseurl, own_key, paths):
    try:
        result = http_request(baseurl + "plop/v1/merge/verifiedsize",
                              key=own_key, verifynode=node,
                              publickeydir=paths["publickeys"])
        parsed_result = json.loads(result)
        if parsed_result.get(u"result") == u"ok":
            return parsed_result[u"size"]
        print >>sys.stderr, "ERROR: verifiedsize", parsed_result
        sys.exit(1)
    except requests.exceptions.HTTPError, e:
        print >>sys.stderr, "ERROR: verifiedsize", e.response
        sys.exit(1)


def sendlog(node, baseurl, own_key, paths, submission):
    try:
        result = http_request(baseurl + "plop/v1/frontend/sendlog",
                              json.dumps(submission), key=own_key,
                              verifynode=node, publickeydir=paths["publickeys"])
        return True, json.loads(result)
    except requests.exceptions.HTTPError, e:
        return False, e.response
    except ValueError, e:
        logging.error("==== FAILED REQUEST ====")
        logging.error(submission)
        logging.error("======= RESPONSE =======")
        logging.error(result)
        logging.error("========================")
        return False, e

def backup_sendlog(node, baseurl, own_key, paths, submission):
    try:
        result = http_request(baseurl + "plop/v1/merge/sendlog",
                              json.dumps(submission), key=own_key,
                              verifynode=node, publickeydir=paths["publickeys"])
        return json.loads(result)
    except requests.exceptions.HTTPError, e:
        print >>sys.stderr, "ERROR: backup_sendlog", e.response
        sys.stderr.flush()
        return None
    except ValueError, e:
        print >>sys.stderr, "==== FAILED REQUEST ===="
        print >>sys.stderr, submission
        print >>sys.stderr, "======= RESPONSE ======="
        print >>sys.stderr, result
        print >>sys.stderr, "========================"
        sys.stderr.flush()
        raise e

def sendentry(node, baseurl, own_key, paths, entry, ehash):
    try:
        result = http_request(
            baseurl + "plop/v1/frontend/sendentry",
            json.dumps({"entry":base64.b64encode(entry),
                        "treeleafhash":base64.b64encode(ehash)}),
            key=own_key, verifynode=node, publickeydir=paths["publickeys"])
        return True, json.loads(result)
    except requests.exceptions.HTTPError, e:
        return False, e.response
    except ValueError, e:
        logging.error("==== FAILED REQUEST ====")
        logging.error(ehash)
        logging.error("======= RESPONSE =======")
        logging.error(result)
        logging.error("========================")
        return False, e

def sendentry_merge(node, baseurl, own_key, paths, entry, ehash):
    return sendentries_merge(node, baseurl, own_key, paths, [(ehash, entry)])

def sendentries_merge(node, baseurl, own_key, paths, entries, session=None):
    try:
        json_entries = [{"entry":base64.b64encode(entry), "treeleafhash":base64.b64encode(ehash)} for ehash, entry in entries]
        result = http_request(
            baseurl + "plop/v1/merge/sendentry",
            json.dumps(json_entries),
            key=own_key, verifynode=node, publickeydir=paths["publickeys"],
            session=session)
        return json.loads(result)
    except requests.exceptions.HTTPError, e:
        print >>sys.stderr, "ERROR: sendentry_merge", e.response
        sys.exit(1)
    except ValueError, e:
        print >>sys.stderr, "==== FAILED REQUEST ===="
        print >>sys.stderr, ehash
        print >>sys.stderr, "======= RESPONSE ======="
        print >>sys.stderr, result
        print >>sys.stderr, "========================"
        sys.stderr.flush()
        raise e

def sendsth(node, baseurl, own_key, paths, submission):
    try:
        result = http_request(baseurl + "plop/v1/frontend/sendsth",
                              json.dumps(submission), key=own_key,
                              verifynode=node, publickeydir=paths["publickeys"])
        return True, json.loads(result)
    except requests.exceptions.HTTPError, e:
        return False, e.response
    except ValueError, e:
        logging.error("==== FAILED REQUEST ====")
        logging.error(submission)
        logging.error("======= RESPONSE =======")
        logging.error(result)
        logging.error("========================")
        return False, e

def verifyroot(node, baseurl, own_key, paths, treesize):
    try:
        result = http_request(baseurl + "plop/v1/merge/verifyroot",
                              json.dumps({"tree_size":treesize}), key=own_key,
                              verifynode=node, publickeydir=paths["publickeys"])
        return json.loads(result)
    except requests.exceptions.HTTPError, e:
        print >>sys.stderr, "ERROR: verifyroot", e.response
        sys.exit(1)
    except ValueError, e:
        print >>sys.stderr, "==== FAILED REQUEST ===="
        print >>sys.stderr, treesize
        print >>sys.stderr, "======= RESPONSE ======="
        print >>sys.stderr, result
        print >>sys.stderr, "========================"
        sys.stderr.flush()
        raise e

def setverifiedsize(node, baseurl, own_key, paths, treesize):
    try:
        result = http_request(baseurl + "plop/v1/merge/setverifiedsize",
                              json.dumps({"size":treesize}), key=own_key,
                              verifynode=node, publickeydir=paths["publickeys"])
        return json.loads(result)
    except requests.exceptions.HTTPError, e:
        print >>sys.stderr, "ERROR: setverifiedsize", e.response
        sys.exit(1)
    except ValueError, e:
        print >>sys.stderr, "==== FAILED REQUEST ===="
        print >>sys.stderr, treesize
        print >>sys.stderr, "======= RESPONSE ======="
        print >>sys.stderr, result
        print >>sys.stderr, "========================"
        sys.stderr.flush()
        raise e

def get_missingentries(node, baseurl, own_key, paths):
    try:
        result = http_request(baseurl + "plop/v1/frontend/missingentries",
                              key=own_key, verifynode=node,
                              publickeydir=paths["publickeys"])
        parsed_result = json.loads(result)
        if parsed_result.get(u"result") == u"ok":
            return parsed_result[u"entries"]
        print >>sys.stderr, "ERROR: missingentries", parsed_result
        sys.exit(1)
    except requests.exceptions.HTTPError, e:
        print >>sys.stderr, "ERROR: missingentries", e.response
        sys.exit(1)

def get_missingentriesforbackup(node, baseurl, own_key, paths):
    try:
        result = http_request(baseurl + "plop/v1/merge/missingentries",
                              key=own_key, verifynode=node,
                              publickeydir=paths["publickeys"])
        parsed_result = json.loads(result)
        if parsed_result.get(u"result") == u"ok":
            return parsed_result[u"entries"]
        print >>sys.stderr, "ERROR: missingentriesforbackup", parsed_result
        sys.exit(1)
    except requests.exceptions.HTTPError, e:
        print >>sys.stderr, "ERROR: missingentriesforbackup", e.response
        sys.exit(1)

def chunks(l, n):
    return [l[i:i+n] for i in range(0, len(l), n)]

def parse_args():
    parser = argparse.ArgumentParser(description="")
    parser.add_argument('node', nargs='*', help="Node to operate on")
    parser.add_argument('--config', help="System configuration",
                        required=True)
    parser.add_argument('--localconfig', help="Local configuration",
                        required=True)
    # FIXME: verify that 0 < N < 1d
    parser.add_argument('--mergeinterval', type=int, metavar="n",
                        help="Merge every N seconds")
    parser.add_argument("--timing", action='store_true',
                        help="Print timing information")
    parser.add_argument("--pidfile", type=str, metavar="file",
                        help="Store PID in FILE")
    parser.add_argument("--logdir", type=str, default=".", metavar="dir",
                        help="Write logfiles in DIR [default: .]")
    parser.add_argument("--loglevel", type=str, default="DEBUG", metavar="level",
                        help="Log level, one of DEBUG, INFO, WARNING, ERROR, CRITICAL [default: DEBUG]")
    args = parser.parse_args()

    config = yaml.load(open(args.config))
    localconfig = yaml.load(open(args.localconfig))

    return (args, config, localconfig)

def perm(dbtype, path):
    if dbtype == "filedb":
        return FileDB(path)
    elif dbtype == "permdb":
        return PermDB(path)
    assert False

def waitforfile(path):
    statinfo = None
    while statinfo is None:
        try:
            statinfo = os.stat(path)
        except OSError, e:
            if e.errno != errno.ENOENT:
                raise
        time.sleep(1)
    return statinfo

def flock_ex_or_fail(path):
    """
    To be used at most once per process. Will otherwise leak file
    descriptors.
    """
    try:
        fcntl.flock(os.open(path, os.O_CREAT), fcntl.LOCK_EX + fcntl.LOCK_NB)
    except IOError, e:
        if e.errno != errno.EWOULDBLOCK:
            raise
        return False
    return True

def flock_ex_wait(path):
    fd = os.open(path, os.O_CREAT)
    logging.debug("waiting for exclusive lock on %s (%s)", fd, path)
    fcntl.flock(fd, fcntl.LOCK_EX)
    logging.debug("taken exclusive lock on %s", fd)
    return fd

def flock_sh_wait(path):
    fd = os.open(path, os.O_CREAT)
    logging.debug("waiting for shared lock on %s (%s)", fd, path)
    fcntl.flock(fd, fcntl.LOCK_SH)
    logging.debug("taken shared lock on %s", fd)
    return fd

def flock_release(fd):
    logging.debug("releasing lock on %s", fd)
    fcntl.flock(fd, fcntl.LOCK_UN)
    os.close(fd)

def terminate_child_procs():
    for p in multiprocessing.active_children():
        #print >>sys.stderr, "DEBUG: terminating pid", p.pid
        p.terminate()

class Status:
    def __init__(self, path):
        self.path = path
    def status(self, s):
        open(self.path, 'w').write(s)

class FileDB:
    def __init__(self, path):
        self.path = path
        self.lockfile = None
    def get(self, key):
        return read_chain(self.path, key)
    def add(self, key, value):
        return write_chain(key, value, self.path)
    def lock_sh(self):
        self.lockfile = flock_sh_wait(self.path + "/.lock")
    def lock_ex(self):
        self.lockfile = flock_ex_wait(self.path + "/.lock")
    def commit(self):
        flock_release(self.lockfile)

class PermDB:
    def __init__(self, path):
        self.permdbobj = permdb.alloc(path)
    def get(self, key):
        return permdb.getvalue(self.permdbobj, key)
    def add(self, key, value):
        return permdb.addvalue(self.permdbobj, key, value)
    def lock_sh(self):
        assert False                                   # NYI
    def lock_ex(self):
        assert False                                   # NYI
    def commit(self):
        permdb.committree(self.permdbobj)