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"""Problem-set search, filtering, sorting and paging.
The catalogue lives in ``leetcode_questions`` and every list the site renders
is produced by one SQL query against it, joined with the signed-in member's
``leetcode_progress`` rows when there is one. Filter state is expressed
entirely in the URL so a filtered list can be linked, refreshed and shared.
"""
from __future__ import annotations
import json
from contextlib import closing
from dataclasses import dataclass, field
from typing import Any, Iterable, Sequence
from urllib.parse import urlencode
from . import content, store
# The captured problem-set page rendered the pinned daily question plus
# questions 1-100 in one uninterrupted list, so one page is exactly that many
# rows. Paging then continues into the rest of the local catalogue.
PER_PAGE = 101
MAX_PAGE = 999
# Every key the query layer accepts. ``frequency`` and ``contest-point`` are
# deliberately absent from the visible sort menu (``content.SORT_OPTIONS``):
# the source prints both behind a Premium lock and captured no values, so the
# clone will not offer them as if they were source facts. They stay orderable
# here because the stored figures are deterministic and the JSON surface is
# expected to sort by any stored column.
SORT_COLUMNS: dict[str, str] = {
"custom": "q.number",
"difficulty": "CASE q.difficulty WHEN 'Easy' THEN 1 WHEN 'Medium' THEN 2"
" ELSE 3 END",
"acceptance": "q.acceptance",
"question-id": "q.number",
"title": "LOWER(q.title)",
"last-submitted": "COALESCE(p.last_submitted_at, '')",
"frequency": "q.frequency",
"contest-point": "q.contest_point",
}
DEFAULT_ORDER: dict[str, str] = {
"custom": "asc",
"difficulty": "asc",
"acceptance": "asc",
"question-id": "asc",
"title": "asc",
"last-submitted": "desc",
"frequency": "desc",
"contest-point": "desc",
}
@dataclass
class ProblemQuery:
category: str = "all"
search: str = ""
difficulty: str = ""
status: str = ""
topics: tuple[str, ...] = ()
language: str = ""
sort: str = "custom"
order: str = ""
page: int = 1
@property
def effective_order(self) -> str:
if self.order in {"asc", "desc"}:
return self.order
return DEFAULT_ORDER.get(self.sort, "asc")
@property
def is_filtered(self) -> bool:
return bool(
self.search
or self.difficulty
or self.status
or self.topics
or self.language
or self.sort != "custom"
or self.order
)
def path(self) -> str:
if self.category and self.category != "all":
return f"/problemset/{self.category}"
return "/problemset/"
def as_params(self, **overrides: Any) -> list[tuple[str, str]]:
values: list[tuple[str, str]] = []
search = overrides.get("search", self.search)
difficulty = overrides.get("difficulty", self.difficulty)
status = overrides.get("status", self.status)
topics = overrides.get("topics", self.topics)
language = overrides.get("language", self.language)
sort = overrides.get("sort", self.sort)
order = overrides.get("order", self.order)
page = overrides.get("page", self.page)
if search:
values.append(("search", search))
if difficulty:
values.append(("difficulty", difficulty))
if status:
values.append(("status", status))
for topic in topics:
values.append(("topic", topic))
if language:
values.append(("language", language))
if sort and sort != "custom":
values.append(("sort", sort))
if order:
values.append(("order", order))
if page and int(page) > 1:
values.append(("page", str(page)))
return values
def url(self, **overrides: Any) -> str:
category = overrides.pop("category", self.category)
base = (
f"/problemset/{category}"
if category and category != "all"
else "/problemset/"
)
params = self.as_params(**overrides)
return f"{base}?{urlencode(params)}" if params else base
def _first(values: Sequence[str]) -> str:
for value in values:
text = str(value).strip()
if text:
return text
return ""
def parse_query(params: Any, category: str = "all") -> ProblemQuery:
"""Build the query state from the request's own URL parameters."""
getlist = getattr(params, "getlist", None)
def values(name: str) -> list[str]:
if getlist is not None:
return [str(item) for item in getlist(name)]
raw = params.get(name)
return [] if raw is None else [str(raw)]
difficulty = _first(values("difficulty"))
if difficulty not in {"", "Easy", "Medium", "Hard"}:
difficulty = ""
status = _first(values("status")).casefold()
if status not in {"", "todo", "solved", "attempted"}:
status = ""
topics = tuple(
topic
for topic in dict.fromkeys(
item.strip() for item in values("topic") if item.strip()
)
if topic in content.ALL_TOPICS
)
language = _first(values("language"))
if language not in content.LANGUAGE_LABELS:
language = ""
sort = _first(values("sort")) or "custom"
if sort not in SORT_COLUMNS:
sort = "custom"
order = _first(values("order")).casefold()
if order not in {"asc", "desc"}:
order = ""
try:
page = int(_first(values("page")) or "1")
except ValueError:
page = 1
page = max(1, min(page, MAX_PAGE))
valid_categories = {slug for slug, _ in content.CATEGORIES}
return ProblemQuery(
category=category if category in valid_categories else "all",
search=_first(values("search"))[:120],
difficulty=difficulty,
status=status,
topics=topics,
language=language,
sort=sort,
order=order,
page=page,
)
@dataclass
class ProblemPage:
rows: list[dict[str, Any]] = field(default_factory=list)
total: int = 0
page: int = 1
per_page: int = PER_PAGE
solved: int = 0
catalogue_total: int = 0
@property
def pages(self) -> int:
return max(1, -(-self.total // self.per_page))
@property
def start_index(self) -> int:
return 0 if not self.total else (self.page - 1) * self.per_page + 1
@property
def end_index(self) -> int:
return min(self.total, self.page * self.per_page)
@property
def is_empty(self) -> bool:
return self.total == 0
def _where(query: ProblemQuery, subject_id: str | None) -> tuple[str, list[Any]]:
clauses: list[str] = []
parameters: list[Any] = []
if query.category != "all":
clauses.append("q.category = ?")
parameters.append(query.category)
if query.search:
clauses.append("(LOWER(q.title) LIKE ? OR CAST(q.number AS TEXT) LIKE ?)")
needle = f"%{query.search.casefold()}%"
parameters.extend([needle, f"%{query.search.strip()}%"])
if query.difficulty:
clauses.append("q.difficulty = ?")
parameters.append(query.difficulty)
for topic in query.topics:
clauses.append("q.topics_json LIKE ?")
parameters.append(f'%"{topic}"%')
if query.language:
clauses.append("q.languages_json LIKE ?")
parameters.append(f'%"{query.language}"%')
if query.status and subject_id:
if query.status == "todo":
clauses.append("p.status IS NULL")
else:
clauses.append("p.status = ?")
parameters.append(query.status)
elif query.status == "solved" and not subject_id:
clauses.append("1 = 0")
return (" AND ".join(clauses) if clauses else "1 = 1"), parameters
def run_query(query: ProblemQuery, subject_id: str | None) -> ProblemPage:
where, parameters = _where(query, subject_id)
column = SORT_COLUMNS.get(query.sort, "q.number")
direction = "ASC" if query.effective_order == "asc" else "DESC"
join_subject = subject_id or ""
# The daily question sits above the list, as the captured page rendered it,
# but only while the visitor has not chosen their own ordering.
pinning = query.sort in {"custom", "question-id"} and not query.order
pin = "CASE WHEN q.slug = ? THEN 0 ELSE 1 END, " if pinning else ""
pin_parameters: list[Any] = [content.DAILY_SLUG] if pinning else []
with closing(store.connect()) as connection:
total_row = connection.execute(
"SELECT COUNT(*) FROM leetcode_questions q"
" LEFT JOIN leetcode_progress p"
" ON p.question_slug = q.slug AND p.subject_id = ?"
f" WHERE {where}",
[join_subject, *parameters],
).fetchone()
total = int(total_row[0]) if total_row is not None else 0
pages = max(1, -(-total // PER_PAGE))
page = min(max(1, query.page), pages)
rows = connection.execute(
"SELECT q.*, p.status AS member_status,"
" p.last_submitted_at AS member_last_submitted"
" FROM leetcode_questions q"
" LEFT JOIN leetcode_progress p"
" ON p.question_slug = q.slug AND p.subject_id = ?"
f" WHERE {where}"
f" ORDER BY {pin}{column} {direction}, q.number ASC"
" LIMIT ? OFFSET ?",
[
join_subject,
*parameters,
*pin_parameters,
PER_PAGE,
(page - 1) * PER_PAGE,
],
).fetchall()
catalogue_row = connection.execute(
"SELECT COUNT(*) FROM leetcode_questions"
).fetchone()
catalogue_total = int(catalogue_row[0]) if catalogue_row is not None else 0
solved = 0
if subject_id:
solved_row = connection.execute(
"SELECT COUNT(*) FROM leetcode_progress"
" WHERE subject_id = ? AND status = 'solved'",
(subject_id,),
).fetchone()
solved = int(solved_row[0]) if solved_row is not None else 0
return ProblemPage(
rows=[_public_row(row) for row in rows],
total=total,
page=page,
solved=solved,
catalogue_total=catalogue_total,
)
def _public_row(row: Any) -> dict[str, Any]:
slug = str(row["slug"])
item = content.question(slug)
return {
"slug": slug,
"number": int(row["number"]),
"title": row["title"],
"difficulty": row["difficulty"],
"difficulty_label": content.difficulty_label(str(row["difficulty"])),
"category": row["category"],
"topics": json.loads(row["topics_json"]),
"languages": json.loads(row["languages_json"]),
"acceptance": float(row["acceptance"]),
"frequency": int(row["frequency"]),
"contest_point": int(row["contest_point"]),
"status": row["member_status"],
"last_submitted": row["member_last_submitted"],
"is_daily": slug == content.DAILY_SLUG,
"workspace_ready": bool(item and item.workspace_ready),
}
def random_slug(query: ProblemQuery, subject_id: str | None, seed: str = "") -> str | None:
"""Pick one question from the active filter for the shuffle control."""
import random
where, parameters = _where(query, subject_id)
with closing(store.connect()) as connection:
slugs = [
str(row["slug"])
for row in connection.execute(
"SELECT q.slug FROM leetcode_questions q"
" LEFT JOIN leetcode_progress p"
" ON p.question_slug = q.slug AND p.subject_id = ?"
f" WHERE {where} ORDER BY q.number",
[subject_id or "", *parameters],
)
]
if not slugs:
return None
chooser = random.Random(seed) if seed else random.Random()
return chooser.choice(slugs)
def topic_counts(category: str = "all") -> list[tuple[str, int]]:
counts: dict[str, int] = {}
for question in content.iter_questions():
if category != "all" and question.category != category:
continue
for topic in question.topics:
counts[topic] = counts.get(topic, 0) + 1
return sorted(counts.items(), key=lambda item: (-item[1], item[0]))
def category_counts() -> dict[str, int]:
counts: dict[str, int] = {"all": 0}
for question in content.iter_questions():
counts["all"] += 1
counts[question.category] = counts.get(question.category, 0) + 1
return counts
def iter_pages(page: int, pages: int) -> Iterable[int]:
window = {1, pages, page, page - 1, page + 1}
return sorted(number for number in window if 1 <= number <= pages)