#!/usr/bin/env python2.7

# Copyright 2015, Google Inc.
# All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are
# met:
#
#     * Redistributions of source code must retain the above copyright
# notice, this list of conditions and the following disclaimer.
#     * Redistributions in binary form must reproduce the above
# copyright notice, this list of conditions and the following disclaimer
# in the documentation and/or other materials provided with the
# distribution.
#     * Neither the name of Google Inc. nor the names of its
# contributors may be used to endorse or promote products derived from
# this software without specific prior written permission.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

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

# 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)

CONFIG = [
    'grpc-timeout',
    'grpc-internal-encoding-request',
    'grpc-payload-bin',
    ':path',
    'grpc-encoding',
    'grpc-accept-encoding',
    'user-agent',
    ':authority',
    'host',
    'grpc-message',
    'grpc-status',
    'grpc-tracing-bin',
    'grpc-stats-bin',
    '',
    ('grpc-status', '0'),
    ('grpc-status', '1'),
    ('grpc-status', '2'),
    ('grpc-encoding', 'identity'),
    ('grpc-encoding', 'gzip'),
    ('grpc-encoding', 'deflate'),
    ('te', 'trailers'),
    ('content-type', 'application/grpc'),
    (':method', 'POST'),
    (':status', '200'),
    (':status', '404'),
    (':scheme', 'http'),
    (':scheme', 'https'),
    (':scheme', 'grpc'),
    (':authority', ''),
    (':method', 'GET'),
    (':method', 'PUT'),
    (':path', '/'),
    (':path', '/index.html'),
    (':status', '204'),
    (':status', '206'),
    (':status', '304'),
    (':status', '400'),
    (':status', '500'),
    ('accept-charset', ''),
    ('accept-encoding', ''),
    ('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', ''),
    ('lb-token', ''),
    ('lb-cost-bin', ''),
    ('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', ''),
]

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

# utility: mangle the name of a config
def mangle(elem):
  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
  if isinstance(elem, tuple):
    return 'grpc_mdelem_%s_%s' % (m0(elem[0]), m0(elem[1]))
  else:
    return 'grpc_mdstr_%s' % (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 = set()
all_elems = set()
static_userdata = {}
for elem in CONFIG:
  if isinstance(elem, tuple):
    all_strs.add(elem[0])
    all_strs.add(elem[1])
    all_elems.add(elem)
  else:
    all_strs.add(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)
  all_strs.add(val)
  all_elems.add(elem)
  compression_elems.append(elem)
  static_userdata[elem] = 1 + (mask | 1)
all_strs = sorted(list(all_strs), key=mangle)
all_elems = sorted(list(all_elems), key=mangle)

# 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.c'), '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.c 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 "src/core/lib/transport/metadata.h"'
print >>H

print >>C, '#include "src/core/lib/transport/static_metadata.h"'
print >>C

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 >>H, 'bool grpc_is_static_metadata_string(grpc_slice slice);'
print >>H
print >>C, 'static uint8_t g_raw_bytes[] = {%s};' % (','.join('%d' % ord(c) for c in ''.join(all_strs)))
print >>C
print >>C, 'static void static_ref(void *unused) {}'
print >>C, 'static void static_unref(grpc_exec_ctx *exec_ctx, void *unused) {}'
print >>C, 'static grpc_slice_refcount g_refcnt = {static_ref, static_unref};'
print >>C
print >>C, 'bool grpc_is_static_metadata_string(grpc_slice slice) {'
print >>C, '  return slice.refcount != NULL && slice.refcount->ref == static_ref;'
print >>C, '};'
print >>C
print >>C, 'const grpc_slice grpc_static_slice_table[GRPC_STATIC_MDSTR_COUNT] = {'
str_ofs = 0
revmap = {}
zero_length_idx = None
for i, elem in enumerate(all_strs):
  print >>C, '{.refcount = &g_refcnt, .data.refcounted = {.bytes = g_raw_bytes+%d, .length=%d}},' % (str_ofs, len(elem))
  revmap[str_ofs] = i
  if len(elem) == 0: zero_length_idx = i
  str_ofs += len(elem);
print >>C, '};'
print >>C
print >>C, 'static const uint8_t g_revmap[] = {%s};' % ','.join('%d' % (revmap[i] if i in revmap else 255) for i in range(0, str_ofs))
print >>C
print >>C, 'int grpc_static_metadata_index(grpc_slice slice) {'
print >>C, '  if (GRPC_SLICE_LENGTH(slice) == 0) return %d;' % zero_length_idx
print >>C, '  size_t ofs = (size_t)(GRPC_SLICE_START_PTR(slice) - g_raw_bytes);'
print >>C, '  if (ofs > sizeof(g_revmap)) return -1;'
print >>C, '  uint8_t id = g_revmap[ofs];'
print >>C, '  return id == 255 ? -1 : id;'
print >>C, '};'
print >>C

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 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_static_mdelem_table[%d])' % (mangle(elem).upper(), i)
print >>H
print >>C, 'grpc_mdelem grpc_static_mdelem_table[GRPC_STATIC_MDELEM_COUNT];'
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 perfect_hash(keys, name):
    tmp = open('/tmp/keys.txt', 'w')
    tmp.write(''.join('%d\n' % (x - min(keys)) for x in keys))
    tmp.close()
    cmd = '%s/perfect/run.sh %s -ds' % (os.path.dirname(sys.argv[0]), tmp.name)
    subprocess.check_call(cmd, shell=True)

    code = ''

    results = {}
    with open('%s/perfect/phash.h' % os.path.dirname(sys.argv[0])) as f:
        txt = f.read()
        for var in ('PHASHLEN', 'PHASHNKEYS', 'PHASHRANGE', 'PHASHSALT'):
            val = re.search(r'#define %s ([0-9a-zA-Z]+)' % var, txt).group(1)
            code += '#define %s_%s %s\n' % (name.upper(), var, val)
            results[var] = val
    code += '\n'
    pycode = 'def f(val):\n'
    pycode += '  val -= %d\n' % min(keys)
    with open('%s/perfect/phash.c' % os.path.dirname(sys.argv[0])) as f:
        txt = f.read()
        tabdata = re.search(r'ub1 tab\[\] = \{([^}]+)\}', txt, re.MULTILINE).group(1)
        code += 'static const uint8_t %s_tab[] = {%s};\n\n' % (name, tabdata)
        func_body = re.search(r'ub4 phash\(val\)\nub4 val;\n\{([^}]+)\}', txt, re.MULTILINE).group(1).replace('ub4', 'uint32_t')
        code += 'static uint32_t %s_phash(uint32_t val) {\nval -= %d;\n%s}\n' % (name,
            min(keys), func_body.replace('tab', '%s_tab' % name))
        pycode += '  tab=(%s)' % tabdata.replace('\n', '')
        pycode += '\n'.join('  %s' % s.strip() for s in func_body.splitlines()[2:])
    g = {}
    exec pycode in g
    pyfunc = g['f']

    results['code'] = code
    results['pyfunc'] = pyfunc
    return results

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 = [-1] * 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 NULL;'
print >>C, '  uint32_t k = (uint32_t)(a * %d + b);' % len(all_strs)
print >>C, '  uint32_t h = elems_phash(k);'
print >>C, '  return elem_keys[h] == k ? &grpc_static_mdelem_table[elem_idxs[h]] : NULL;'
print >>C, '}'
print >>C

print >>H, 'extern const uint8_t grpc_static_metadata_elem_indices[GRPC_STATIC_MDELEM_COUNT*2];'
print >>C, 'const uint8_t grpc_static_metadata_elem_indices[GRPC_STATIC_MDELEM_COUNT*2] = {'
print >>C, ','.join('%d' % str_idx(x) for x in itertools.chain.from_iterable([a,b] for a, b in all_elems))
print >>C, '};'
print >>C

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_static_mdelem_table[grpc_static_accept_encoding_metadata[(algs)]])'

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

H.close()
C.close()