#!/usr/bin/env python2.7

# Copyright 2015 gRPC authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import hashlib
import itertools
import collections
import os
import sys
import subprocess
import re
import perfection

# Configuration: a list of either strings or 2-tuples of strings.
# A single string represents a static grpc_mdstr.
# A 2-tuple represents a static grpc_mdelem (and appropriate grpc_mdstrs will
# also be created).
# The list of 2-tuples must begin with the static hpack table elements as
# defined by RFC 7541 and be in the same order because of an hpack encoding
# performance optimization that relies on this. If you want to change this, then
# you must change the implementation of the encoding optimization as well.

CONFIG = [
    # metadata strings
    'host',
    'grpc-timeout',
    'grpc-internal-encoding-request',
    'grpc-internal-stream-encoding-request',
    'grpc-payload-bin',
    ':path',
    'grpc-encoding',
    'grpc-accept-encoding',
    'user-agent',
    ':authority',
    'grpc-message',
    'grpc-status',
    'grpc-server-stats-bin',
    'grpc-tags-bin',
    'grpc-trace-bin',
    'grpc-previous-rpc-attempts',
    'grpc-retry-pushback-ms',
    '1',
    '2',
    '3',
    '4',
    '',
    # channel arg keys
    'grpc.wait_for_ready',
    'grpc.timeout',
    'grpc.max_request_message_bytes',
    'grpc.max_response_message_bytes',
    # well known method names
    '/grpc.lb.v1.LoadBalancer/BalanceLoad',
    '/grpc.health.v1.Health/Watch',
    '/envoy.service.discovery.v2.AggregatedDiscoveryService/StreamAggregatedResources',
    # compression algorithm names
    'deflate',
    'gzip',
    'stream/gzip',
    # metadata elements
    # begin hpack static elements
    (':authority', ''),
    (':method', 'GET'),
    (':method', 'POST'),
    (':path', '/'),
    (':path', '/index.html'),
    (':scheme', 'http'),
    (':scheme', 'https'),
    (':status', '200'),
    (':status', '204'),
    (':status', '206'),
    (':status', '304'),
    (':status', '400'),
    (':status', '404'),
    (':status', '500'),
    ('accept-charset', ''),
    ('accept-encoding', 'gzip, deflate'),
    ('accept-language', ''),
    ('accept-ranges', ''),
    ('accept', ''),
    ('access-control-allow-origin', ''),
    ('age', ''),
    ('allow', ''),
    ('authorization', ''),
    ('cache-control', ''),
    ('content-disposition', ''),
    ('content-encoding', ''),
    ('content-language', ''),
    ('content-length', ''),
    ('content-location', ''),
    ('content-range', ''),
    ('content-type', ''),
    ('cookie', ''),
    ('date', ''),
    ('etag', ''),
    ('expect', ''),
    ('expires', ''),
    ('from', ''),
    ('host', ''),
    ('if-match', ''),
    ('if-modified-since', ''),
    ('if-none-match', ''),
    ('if-range', ''),
    ('if-unmodified-since', ''),
    ('last-modified', ''),
    ('link', ''),
    ('location', ''),
    ('max-forwards', ''),
    ('proxy-authenticate', ''),
    ('proxy-authorization', ''),
    ('range', ''),
    ('referer', ''),
    ('refresh', ''),
    ('retry-after', ''),
    ('server', ''),
    ('set-cookie', ''),
    ('strict-transport-security', ''),
    ('transfer-encoding', ''),
    ('user-agent', ''),
    ('vary', ''),
    ('via', ''),
    ('www-authenticate', ''),
    # end hpack static elements
    ('grpc-status', '0'),
    ('grpc-status', '1'),
    ('grpc-status', '2'),
    ('grpc-encoding', 'identity'),
    ('grpc-encoding', 'gzip'),
    ('grpc-encoding', 'deflate'),
    ('te', 'trailers'),
    ('content-type', 'application/grpc'),
    (':scheme', 'grpc'),
    (':method', 'PUT'),
    ('accept-encoding', ''),
    ('content-encoding', 'identity'),
    ('content-encoding', 'gzip'),
    ('lb-token', ''),
    ('lb-cost-bin', ''),
]

# All entries here are ignored when counting non-default initial metadata that
# prevents the chttp2 server from sending a Trailers-Only response.
METADATA_BATCH_CALLOUTS = [
    # (name)
    (':path'),
    (':method'),
    (':status'),
    (':authority'),
    (':scheme'),
    ('te'),
    ('grpc-message'),
    ('grpc-status'),
    ('grpc-payload-bin'),
    ('grpc-encoding'),
    ('grpc-accept-encoding'),
    ('grpc-server-stats-bin'),
    ('grpc-tags-bin'),
    ('grpc-trace-bin'),
    ('content-type'),
    ('content-encoding'),
    ('accept-encoding'),
    ('grpc-internal-encoding-request'),
    ('grpc-internal-stream-encoding-request'),
    ('user-agent'),
    ('host'),
    ('lb-token'),
    ('grpc-previous-rpc-attempts'),
    ('grpc-retry-pushback-ms'),
]

COMPRESSION_ALGORITHMS = [
    'identity',
    'deflate',
    'gzip',
]

STREAM_COMPRESSION_ALGORITHMS = [
    'identity',
    'gzip',
]


# utility: mangle the name of a config
def mangle(elem, name=None):
    xl = {
        '-': '_',
        ':': '',
        '/': 'slash',
        '.': 'dot',
        ',': 'comma',
        ' ': '_',
    }

    def m0(x):
        if not x:
            return 'empty'
        r = ''
        for c in x:
            put = xl.get(c, c.lower())
            if not put:
                continue
            last_is_underscore = r[-1] == '_' if r else True
            if last_is_underscore and put == '_':
                continue
            elif len(put) > 1:
                if not last_is_underscore:
                    r += '_'
                r += put
                r += '_'
            else:
                r += put
        if r[-1] == '_':
            r = r[:-1]
        return r

    def n(default, name=name):
        if name is None:
            return 'grpc_%s_' % default
        if name == '':
            return ''
        return 'grpc_%s_' % name

    if isinstance(elem, tuple):
        return '%s%s_%s' % (n('mdelem'), m0(elem[0]), m0(elem[1]))
    else:
        return '%s%s' % (n('mdstr'), m0(elem))


# utility: generate some hash value for a string
def fake_hash(elem):
    return hashlib.md5(elem).hexdigest()[0:8]


# utility: print a big comment block into a set of files
def put_banner(files, banner):
    for f in files:
        print >> f, '/*'
        for line in banner:
            print >> f, ' * %s' % line
        print >> f, ' */'
        print >> f


# build a list of all the strings we need
all_strs = list()
all_elems = list()
static_userdata = {}
# put metadata batch callouts first, to make the check of if a static metadata
# string is a callout trivial
for elem in METADATA_BATCH_CALLOUTS:
    if elem not in all_strs:
        all_strs.append(elem)
for elem in CONFIG:
    if isinstance(elem, tuple):
        if elem[0] not in all_strs:
            all_strs.append(elem[0])
        if elem[1] not in all_strs:
            all_strs.append(elem[1])
        if elem not in all_elems:
            all_elems.append(elem)
    else:
        if elem not in all_strs:
            all_strs.append(elem)
compression_elems = []
for mask in range(1, 1 << len(COMPRESSION_ALGORITHMS)):
    val = ','.join(COMPRESSION_ALGORITHMS[alg]
                   for alg in range(0, len(COMPRESSION_ALGORITHMS))
                   if (1 << alg) & mask)
    elem = ('grpc-accept-encoding', val)
    if val not in all_strs:
        all_strs.append(val)
    if elem not in all_elems:
        all_elems.append(elem)
    compression_elems.append(elem)
    static_userdata[elem] = 1 + (mask | 1)
stream_compression_elems = []
for mask in range(1, 1 << len(STREAM_COMPRESSION_ALGORITHMS)):
    val = ','.join(STREAM_COMPRESSION_ALGORITHMS[alg]
                   for alg in range(0, len(STREAM_COMPRESSION_ALGORITHMS))
                   if (1 << alg) & mask)
    elem = ('accept-encoding', val)
    if val not in all_strs:
        all_strs.append(val)
    if elem not in all_elems:
        all_elems.append(elem)
    stream_compression_elems.append(elem)
    static_userdata[elem] = 1 + (mask | 1)

# output configuration
args = sys.argv[1:]
H = None
C = None
D = None
if args:
    if 'header' in args:
        H = sys.stdout
    else:
        H = open('/dev/null', 'w')
    if 'source' in args:
        C = sys.stdout
    else:
        C = open('/dev/null', 'w')
    if 'dictionary' in args:
        D = sys.stdout
    else:
        D = open('/dev/null', 'w')
else:
    H = open(
        os.path.join(
            os.path.dirname(sys.argv[0]),
            '../../../src/core/lib/transport/static_metadata.h'), 'w')
    C = open(
        os.path.join(
            os.path.dirname(sys.argv[0]),
            '../../../src/core/lib/transport/static_metadata.cc'), 'w')
    D = open(
        os.path.join(
            os.path.dirname(sys.argv[0]),
            '../../../test/core/end2end/fuzzers/hpack.dictionary'), 'w')

# copy-paste copyright notice from this file
with open(sys.argv[0]) as my_source:
    copyright = []
    for line in my_source:
        if line[0] != '#':
            break
    for line in my_source:
        if line[0] == '#':
            copyright.append(line)
            break
    for line in my_source:
        if line[0] != '#':
            break
        copyright.append(line)
    put_banner([H, C], [line[2:].rstrip() for line in copyright])

hex_bytes = [ord(c) for c in 'abcdefABCDEF0123456789']


def esc_dict(line):
    out = "\""
    for c in line:
        if 32 <= c < 127:
            if c != ord('"'):
                out += chr(c)
            else:
                out += "\\\""
        else:
            out += '\\x%02X' % c
    return out + "\""


put_banner([H, C], """WARNING: Auto-generated code.

To make changes to this file, change
tools/codegen/core/gen_static_metadata.py, and then re-run it.

See metadata.h for an explanation of the interface here, and metadata.cc for
an explanation of what's going on.
""".splitlines())

print >> H, '#ifndef GRPC_CORE_LIB_TRANSPORT_STATIC_METADATA_H'
print >> H, '#define GRPC_CORE_LIB_TRANSPORT_STATIC_METADATA_H'
print >> H
print >> H, '#include <grpc/support/port_platform.h>'
print >> H
print >> H, '#include "src/core/lib/transport/metadata.h"'
print >> H
print >> C, '#include <grpc/support/port_platform.h>'
print >> C
print >> C, '#include "src/core/lib/transport/static_metadata.h"'
print >> C
print >> C, '#include "src/core/lib/slice/slice_internal.h"'
print >> C

str_ofs = 0
id2strofs = {}
for i, elem in enumerate(all_strs):
    id2strofs[i] = str_ofs
    str_ofs += len(elem)


def slice_def(i):
    return ('{&grpc_static_metadata_refcounts[%d],'
            ' {{%d, g_bytes+%d}}}') % (i, len(all_strs[i]), id2strofs[i])


# validate configuration
for elem in METADATA_BATCH_CALLOUTS:
    assert elem in all_strs

print >> H, '#define GRPC_STATIC_MDSTR_COUNT %d' % len(all_strs)
print >> H, ('extern const grpc_slice '
             'grpc_static_slice_table[GRPC_STATIC_MDSTR_COUNT];')
for i, elem in enumerate(all_strs):
    print >> H, '/* "%s" */' % elem
    print >> H, '#define %s (grpc_static_slice_table[%d])' % (
        mangle(elem).upper(), i)
print >> H
print >> C, 'static uint8_t g_bytes[] = {%s};' % (','.join(
    '%d' % ord(c) for c in ''.join(all_strs)))
print >> C
print >> C, ('static grpc_slice_refcount static_sub_refcnt;')
print >> H, ('extern grpc_slice_refcount '
             'grpc_static_metadata_refcounts[GRPC_STATIC_MDSTR_COUNT];')
print >> C, ('grpc_slice_refcount '
             'grpc_static_metadata_refcounts[GRPC_STATIC_MDSTR_COUNT] = {')
for i, elem in enumerate(all_strs):
    print >> C, ('  grpc_slice_refcount(&static_sub_refcnt, '
                 'grpc_slice_refcount::Type::STATIC), ')
print >> C, '};'
print >> C
print >> H, '#define GRPC_IS_STATIC_METADATA_STRING(slice) \\'
print >> H, ('  ((slice).refcount != NULL && (slice).refcount->GetType() == '
             'grpc_slice_refcount::Type::STATIC)')
print >> H
print >> C, ('const grpc_slice grpc_static_slice_table[GRPC_STATIC_MDSTR_COUNT]'
             ' = {')
for i, elem in enumerate(all_strs):
    print >> C, slice_def(i) + ','
print >> C, '};'
print >> C
print >> H, '#define GRPC_STATIC_METADATA_INDEX(static_slice) \\'
print >> H, ('  ((int)((static_slice).refcount - '
             'grpc_static_metadata_refcounts))')
print >> H

print >> D, '# hpack fuzzing dictionary'
for i, elem in enumerate(all_strs):
    print >> D, '%s' % (esc_dict([len(elem)] + [ord(c) for c in elem]))
for i, elem in enumerate(all_elems):
    print >> D, '%s' % (esc_dict([0, len(elem[0])] + [ord(c) for c in elem[0]] +
                                 [len(elem[1])] + [ord(c) for c in elem[1]]))

print >> H, '#define GRPC_STATIC_MDELEM_COUNT %d' % len(all_elems)
print >> H, ('extern grpc_mdelem_data '
             'grpc_static_mdelem_table[GRPC_STATIC_MDELEM_COUNT];')
print >> H, ('extern uintptr_t '
             'grpc_static_mdelem_user_data[GRPC_STATIC_MDELEM_COUNT];')
for i, elem in enumerate(all_elems):
    print >> H, '/* "%s": "%s" */' % elem
    print >> H, ('#define %s (GRPC_MAKE_MDELEM(&grpc_static_mdelem_table[%d], '
                 'GRPC_MDELEM_STORAGE_STATIC))') % (mangle(elem).upper(), i)
print >> H

print >> C, ('uintptr_t grpc_static_mdelem_user_data[GRPC_STATIC_MDELEM_COUNT] '
             '= {')
print >> C, '  %s' % ','.join(
    '%d' % static_userdata.get(elem, 0) for elem in all_elems)
print >> C, '};'
print >> C


def str_idx(s):
    for i, s2 in enumerate(all_strs):
        if s == s2:
            return i


def md_idx(m):
    for i, m2 in enumerate(all_elems):
        if m == m2:
            return i


def offset_trials(mink):
    yield 0
    for i in range(1, 100):
        for mul in [-1, 1]:
            yield mul * i


def perfect_hash(keys, name):
    p = perfection.hash_parameters(keys)

    def f(i, p=p):
        i += p.offset
        x = i % p.t
        y = i / p.t
        return x + p.r[y]

    return {
        'PHASHRANGE': p.t - 1 + max(p.r),
        'PHASHNKEYS': len(p.slots),
        'pyfunc': f,
        'code': """
static const int8_t %(name)s_r[] = {%(r)s};
static uint32_t %(name)s_phash(uint32_t i) {
  i %(offset_sign)s= %(offset)d;
  uint32_t x = i %% %(t)d;
  uint32_t y = i / %(t)d;
  uint32_t h = x;
  if (y < GPR_ARRAY_SIZE(%(name)s_r)) {
    uint32_t delta = (uint32_t)%(name)s_r[y];
    h += delta;
  }
  return h;
}
    """ % {
            'name': name,
            'r': ','.join('%d' % (r if r is not None else 0) for r in p.r),
            't': p.t,
            'offset': abs(p.offset),
            'offset_sign': '+' if p.offset > 0 else '-'
        }
    }


elem_keys = [
    str_idx(elem[0]) * len(all_strs) + str_idx(elem[1]) for elem in all_elems
]
elem_hash = perfect_hash(elem_keys, 'elems')
print >> C, elem_hash['code']

keys = [0] * int(elem_hash['PHASHRANGE'])
idxs = [255] * int(elem_hash['PHASHNKEYS'])
for i, k in enumerate(elem_keys):
    h = elem_hash['pyfunc'](k)
    assert keys[h] == 0
    keys[h] = k
    idxs[h] = i
print >> C, 'static const uint16_t elem_keys[] = {%s};' % ','.join(
    '%d' % k for k in keys)
print >> C, 'static const uint8_t elem_idxs[] = {%s};' % ','.join(
    '%d' % i for i in idxs)
print >> C

print >> H, 'grpc_mdelem grpc_static_mdelem_for_static_strings(int a, int b);'
print >> C, 'grpc_mdelem grpc_static_mdelem_for_static_strings(int a, int b) {'
print >> C, '  if (a == -1 || b == -1) return GRPC_MDNULL;'
print >> C, '  uint32_t k = (uint32_t)(a * %d + b);' % len(all_strs)
print >> C, '  uint32_t h = elems_phash(k);'
print >> C, '  return h < GPR_ARRAY_SIZE(elem_keys) && elem_keys[h] == k && elem_idxs[h] != 255 ? GRPC_MAKE_MDELEM(&grpc_static_mdelem_table[elem_idxs[h]], GRPC_MDELEM_STORAGE_STATIC) : GRPC_MDNULL;'
print >> C, '}'
print >> C

print >> C, 'grpc_mdelem_data grpc_static_mdelem_table[GRPC_STATIC_MDELEM_COUNT] = {'
for a, b in all_elems:
    print >> C, '{%s,%s},' % (slice_def(str_idx(a)), slice_def(str_idx(b)))
print >> C, '};'

print >> H, 'typedef enum {'
for elem in METADATA_BATCH_CALLOUTS:
    print >> H, '  %s,' % mangle(elem, 'batch').upper()
print >> H, '  GRPC_BATCH_CALLOUTS_COUNT'
print >> H, '} grpc_metadata_batch_callouts_index;'
print >> H
print >> H, 'typedef union {'
print >> H, '  struct grpc_linked_mdelem *array[GRPC_BATCH_CALLOUTS_COUNT];'
print >> H, '  struct {'
for elem in METADATA_BATCH_CALLOUTS:
    print >> H, '  struct grpc_linked_mdelem *%s;' % mangle(elem, '').lower()
print >> H, '  } named;'
print >> H, '} grpc_metadata_batch_callouts;'
print >> H
print >> H, '#define GRPC_BATCH_INDEX_OF(slice) \\'
print >> H, '  (GRPC_IS_STATIC_METADATA_STRING((slice)) ? (grpc_metadata_batch_callouts_index)GPR_CLAMP(GRPC_STATIC_METADATA_INDEX((slice)), 0, GRPC_BATCH_CALLOUTS_COUNT) : GRPC_BATCH_CALLOUTS_COUNT)'
print >> H

print >> H, 'extern const uint8_t grpc_static_accept_encoding_metadata[%d];' % (
    1 << len(COMPRESSION_ALGORITHMS))
print >> C, 'const uint8_t grpc_static_accept_encoding_metadata[%d] = {' % (
    1 << len(COMPRESSION_ALGORITHMS))
print >> C, '0,%s' % ','.join('%d' % md_idx(elem) for elem in compression_elems)
print >> C, '};'
print >> C

print >> H, '#define GRPC_MDELEM_ACCEPT_ENCODING_FOR_ALGORITHMS(algs) (GRPC_MAKE_MDELEM(&grpc_static_mdelem_table[grpc_static_accept_encoding_metadata[(algs)]], GRPC_MDELEM_STORAGE_STATIC))'
print >> H

print >> H, 'extern const uint8_t grpc_static_accept_stream_encoding_metadata[%d];' % (
    1 << len(STREAM_COMPRESSION_ALGORITHMS))
print >> C, 'const uint8_t grpc_static_accept_stream_encoding_metadata[%d] = {' % (
    1 << len(STREAM_COMPRESSION_ALGORITHMS))
print >> C, '0,%s' % ','.join(
    '%d' % md_idx(elem) for elem in stream_compression_elems)
print >> C, '};'

print >> H, '#define GRPC_MDELEM_ACCEPT_STREAM_ENCODING_FOR_ALGORITHMS(algs) (GRPC_MAKE_MDELEM(&grpc_static_mdelem_table[grpc_static_accept_stream_encoding_metadata[(algs)]], GRPC_MDELEM_STORAGE_STATIC))'

print >> H, '#endif /* GRPC_CORE_LIB_TRANSPORT_STATIC_METADATA_H */'

H.close()
C.close()