File size: 9,683 Bytes
1d9bd9b | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 | """Verified source-PDF resolution for the judgment viewer.
The open SCR registry contains a small number of keys whose objects exist and are
labelled ``application/pdf`` but whose payload is actually an HTML error page.
Treating map membership as PDF availability therefore creates a false-positive
"Official PDF" tab.
This module keeps all duplicate source candidates, verifies the payload with a
bounded byte-range request, and caches only the verification result. The browser
can then load the verified public source directly, preserving byte-range support
without routing a large PDF through the CPU Space.
"""
from __future__ import annotations
from dataclasses import asdict, dataclass
import json
import os
import re
import threading
import time
from typing import Dict, Iterable, List, Optional
import requests
DEFAULT_PDF_BASE = "https://indian-supreme-court-judgments.s3.ap-south-1.amazonaws.com"
OFFICIAL_SCR_SEARCH = "https://scr.sci.gov.in/scrsearch/"
PDF_MAGIC = b"%PDF"
PROBE_BYTES = 1024
MIN_PDF_BYTES = 1024
@dataclass(frozen=True)
class PdfStatus:
status: str
url: Optional[str] = None
reason: Optional[str] = None
size: Optional[int] = None
provider: Optional[str] = None
source_key: Optional[str] = None
fallback_available: bool = False
@property
def verified(self) -> bool:
return self.status == "verified"
def public_dict(self) -> dict:
data = asdict(self)
data["verified"] = self.verified
data["source_name"] = (
"Supreme Court Reports open registry (AWS Open Data)"
if self.provider == "aws_open_data"
else "Bharat Courts public archive"
if self.provider == "bharat_courts"
else "Supreme Court source archive"
)
data["official_search_url"] = OFFICIAL_SCR_SEARCH
return data
def _identity_key(value: object) -> str:
"""Normalize a public citation/identity without conflating case titles."""
return re.sub(r"[^A-Z0-9]+", " ", str(value or "").upper()).strip()
def _total_size(response: requests.Response) -> Optional[int]:
content_range = response.headers.get("content-range", "")
if "/" in content_range:
try:
return int(content_range.rsplit("/", 1)[1])
except (TypeError, ValueError):
pass
try:
return int(response.headers.get("content-length", ""))
except (TypeError, ValueError):
return None
class PdfSourceResolver:
"""Resolve and verify mapped PDFs without downloading the whole document."""
def __init__(
self,
map_path: str,
base_url: str = DEFAULT_PDF_BASE,
*,
request_timeout: tuple = (5, 15),
verified_ttl: int = 24 * 60 * 60,
invalid_ttl: int = 6 * 60 * 60,
temporary_ttl: int = 60,
):
self.base_url = base_url.rstrip("/")
self.request_timeout = request_timeout
self.verified_ttl = verified_ttl
self.invalid_ttl = invalid_ttl
self.temporary_ttl = temporary_ttl
self.sources: Dict[str, List[str]] = {}
self.archive_candidates: Dict[str, List[dict]] = {}
self._cache: Dict[str, tuple] = {}
self._lock = threading.Lock()
self._load(map_path)
def _load(self, map_path: str) -> None:
if not os.path.exists(map_path):
return
with open(map_path, encoding="utf-8") as fh:
for line in fh:
try:
row = json.loads(line)
doc_id = _identity_key(row["doc_id"])
year = str(row["year"])
path = str(row["path"])
except (KeyError, TypeError, ValueError, json.JSONDecodeError):
continue
url = f"{self.base_url}/data/pdf/year={year}/english/{path}_EN.pdf"
candidates = self.sources.setdefault(doc_id, [])
if url not in candidates:
candidates.append(url)
archive = self.archive_candidates.setdefault(doc_id, [])
record = {"year": year, "path": path, "source_key": doc_id}
if record not in archive:
archive.append(record)
@property
def mapped_count(self) -> int:
return len(self.sources)
@staticmethod
def _keys(doc_id: str, aliases: Optional[Iterable[object]] = None) -> list[str]:
keys = []
for value in [doc_id, *(aliases or [])]:
key = _identity_key(value)
if key and key not in keys:
keys.append(key)
return keys
def mapped(self, doc_id: str, aliases: Optional[Iterable[object]] = None) -> bool:
return any(key in self.sources for key in self._keys(doc_id, aliases))
def _resolved_candidates(
self, doc_id: str, aliases: Optional[Iterable[object]] = None
) -> list[tuple[str, str]]:
resolved = []
for key in self._keys(doc_id, aliases):
for url in self.sources.get(key, []):
item = (url, key)
if item not in resolved:
resolved.append(item)
return resolved
def archive_candidate(
self, doc_id: str, aliases: Optional[Iterable[object]] = None
) -> Optional[dict]:
"""Return a trusted year/path for Bharat Courts' tar fallback."""
for key in self._keys(doc_id, aliases):
candidates = self.archive_candidates.get(key, [])
if candidates:
return dict(candidates[-1])
return None
def _cached(self, cache_key: str) -> Optional[PdfStatus]:
with self._lock:
item = self._cache.get(cache_key)
if not item:
return None
expires, status = item
if expires <= time.monotonic():
self._cache.pop(cache_key, None)
return None
return status
def _store(self, cache_key: str, status: PdfStatus) -> PdfStatus:
if status.status == "verified":
ttl = self.verified_ttl
elif status.status == "temporarily_unavailable":
ttl = self.temporary_ttl
else:
ttl = self.invalid_ttl
with self._lock:
self._cache[cache_key] = (time.monotonic() + ttl, status)
return status
def probe(
self,
doc_id: str,
*,
aliases: Optional[Iterable[object]] = None,
force: bool = False,
) -> PdfStatus:
keys = self._keys(doc_id, aliases)
cache_key = "|".join(keys)
if not force:
cached = self._cached(cache_key)
if cached:
return cached
candidates = self._resolved_candidates(doc_id, aliases)
if not candidates:
return self._store(cache_key, PdfStatus("not_mapped", reason="no_pdf_mapping"))
invalid_reasons: List[str] = []
temporary_reasons: List[str] = []
# The old dictionary loader used the last duplicate row. Try that first
# for continuity, but retain earlier candidates as fallbacks.
for url, source_key in reversed(candidates):
response = None
try:
response = requests.get(
url,
headers={"Range": f"bytes=0-{PROBE_BYTES - 1}"},
stream=True,
allow_redirects=True,
timeout=self.request_timeout,
)
status_code = response.status_code
if status_code not in (200, 206):
reason = f"http_{status_code}"
if status_code >= 500 or status_code in (408, 429):
temporary_reasons.append(reason)
else:
invalid_reasons.append(reason)
continue
prefix = response.raw.read(PROBE_BYTES, decode_content=True)
size = _total_size(response)
if size is not None and size < MIN_PDF_BYTES:
invalid_reasons.append(f"too_small_{size}")
continue
if PDF_MAGIC not in prefix[:PROBE_BYTES]:
invalid_reasons.append("payload_is_not_pdf")
continue
return self._store(
cache_key,
PdfStatus(
"verified",
url=url,
size=size,
provider="aws_open_data",
source_key=source_key,
fallback_available=True,
),
)
except requests.RequestException as exc:
temporary_reasons.append(type(exc).__name__)
finally:
if response is not None:
response.close()
# If any candidate could not be checked, fail transiently rather than
# making the stronger claim that every mapped source is invalid.
if temporary_reasons:
return self._store(
cache_key,
PdfStatus(
"temporarily_unavailable",
reason=";".join(dict.fromkeys(temporary_reasons)),
fallback_available=True,
),
)
return self._store(
cache_key,
PdfStatus(
"invalid_source",
reason=";".join(dict.fromkeys(invalid_reasons)) or "source_probe_failed",
fallback_available=True,
),
)
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