vienalatina/apps/board/board.py

"""Threads and comments.

A deliberate split between two things often lumped together as "moderation":

* **Deleting** someone else's post is an admin power. Sometimes something has
  to come down, and the person who wrote it is not always around to do it.
* **Editing** someone else's post is nobody's power but the author's. An admin
  who could rewrite a member's words could put a sentence in their mouth that
  the member gets to see attributed to themselves. Removing is visible;
  silently rewriting is not.

The plan drafted for this feature said admins could do both. This is the one
place the implementation departs from it, on purpose.
"""

from __future__ import annotations

from flask import (Blueprint, abort, current_app, flash, g, redirect,
                   render_template, request, url_for)

from .db import get_db
from .render import excerpt, to_html
from .security import admin_required, login_required

bp = Blueprint("board", __name__)

PER_PAGE = 20
TITLE_MAX = 140
BODY_MAX = 20_000


def is_admin() -> bool:
    return g.member["role"] in ("owner", "admin")


def may_delete(row) -> bool:
    return is_admin() or row["author_id"] == g.member["id"]


def may_edit(row) -> bool:
    return row["author_id"] == g.member["id"]


def cooldown_remaining() -> int:
    """Seconds this member must still wait. Guards against a stuck key or a
    double-submitted form, not against a determined spammer — the door is the
    members table, and everyone behind it is known."""
    seconds = current_app.config["COOLDOWN_SECONDS"]
    if seconds <= 0:
        return 0
    row = get_db().execute(
        """SELECT MAX(created_at) AS last FROM (
               SELECT created_at FROM threads  WHERE author_id = :id
               UNION ALL
               SELECT created_at FROM comments WHERE author_id = :id
           )""",
        {"id": g.member["id"]},
    ).fetchone()
    if not row or not row["last"]:
        return 0
    elapsed = get_db().execute(
        "SELECT CAST(strftime('%s','now') AS INTEGER) - CAST(strftime('%s', ?) AS INTEGER) AS s",
        (row["last"],),
    ).fetchone()["s"]
    return max(0, seconds - int(elapsed))


def _clean(title: str, body: str) -> tuple[str, str] | None:
    title = title.strip()[:TITLE_MAX]
    body = body.strip()[:BODY_MAX]
    if not title or not body:
        flash("El título y el mensaje no pueden estar vacíos.", "error")
        return None
    return title, body


def _thread_or_404(thread_id: int):
    row = get_db().execute(
        "SELECT * FROM threads WHERE id = ? AND deleted_at IS NULL", (thread_id,)
    ).fetchone()
    if row is None:
        abort(404)
    return row


def _comment_or_404(comment_id: int):
    row = get_db().execute(
        "SELECT * FROM comments WHERE id = ? AND deleted_at IS NULL", (comment_id,)
    ).fetchone()
    if row is None:
        abort(404)
    return row


@bp.route("/")
@login_required
def threads():
    page = max(1, request.args.get("page", 1, type=int))
    rows = get_db().execute(
        """SELECT t.*, m.display_name AS author,
                  (SELECT COUNT(*) FROM comments c
                    WHERE c.thread_id = t.id AND c.deleted_at IS NULL) AS replies
             FROM threads t JOIN members m ON m.id = t.author_id
            WHERE t.deleted_at IS NULL
            ORDER BY t.pinned DESC, t.created_at DESC
            LIMIT ? OFFSET ?""",
        (PER_PAGE + 1, (page - 1) * PER_PAGE),
    ).fetchall()
    # One row past the page size answers "is there a next page" without a
    # second COUNT(*) over the whole table.
    has_next = len(rows) > PER_PAGE
    return render_template("threads.html", threads=rows[:PER_PAGE], page=page,
                           has_next=has_next, excerpt=excerpt)


@bp.route("/tema/<int:thread_id>")
@login_required
def thread(thread_id: int):
    row = _thread_or_404(thread_id)
    db = get_db()
    author = db.execute("SELECT display_name FROM members WHERE id = ?",
                        (row["author_id"],)).fetchone()
    comments = db.execute(
        """SELECT c.*, m.display_name AS author
             FROM comments c JOIN members m ON m.id = c.author_id
            WHERE c.thread_id = ? AND c.deleted_at IS NULL
            ORDER BY c.created_at""",
        (thread_id,),
    ).fetchall()
    return render_template("thread.html", thread=row, author=author["display_name"],
                           comments=comments, body_html=to_html(row["body_md"]),
                           to_html=to_html, may_edit=may_edit, may_delete=may_delete,
                           is_admin=is_admin())


@bp.route("/nuevo", methods=["GET", "POST"])
@login_required
def new_thread():
    if request.method == "GET":
        return render_template("thread_form.html", thread=None)

    cleaned = _clean(request.form.get("title", ""), request.form.get("body", ""))
    if cleaned is None:
        return redirect(url_for("board.new_thread"))
    wait = cooldown_remaining()
    if wait:
        flash(f"Espera {wait} segundos antes de publicar otra vez.", "error")
        return redirect(url_for("board.new_thread"))

    title, body = cleaned
    cursor = get_db().execute(
        "INSERT INTO threads (author_id, title, body_md) VALUES (?, ?, ?)",
        (g.member["id"], title, body),
    )
    return redirect(url_for("board.thread", thread_id=cursor.lastrowid))


@bp.route("/tema/<int:thread_id>/editar", methods=["GET", "POST"])
@login_required
def edit_thread(thread_id: int):
    row = _thread_or_404(thread_id)
    if not may_edit(row):
        abort(403)
    if request.method == "GET":
        return render_template("thread_form.html", thread=row)

    cleaned = _clean(request.form.get("title", ""), request.form.get("body", ""))
    if cleaned is None:
        return redirect(url_for("board.edit_thread", thread_id=thread_id))
    title, body = cleaned
    get_db().execute(
        "UPDATE threads SET title = ?, body_md = ?, edited_at = datetime('now') WHERE id = ?",
        (title, body, thread_id),
    )
    return redirect(url_for("board.thread", thread_id=thread_id))


@bp.route("/tema/<int:thread_id>/eliminar", methods=["POST"])
@login_required
def delete_thread(thread_id: int):
    row = _thread_or_404(thread_id)
    if not may_delete(row):
        abort(403)
    get_db().execute("UPDATE threads SET deleted_at = datetime('now') WHERE id = ?", (thread_id,))
    flash("Tema eliminado.", "ok")
    return redirect(url_for("board.threads"))


@bp.route("/tema/<int:thread_id>/comentar", methods=["POST"])
@login_required
def comment(thread_id: int):
    row = _thread_or_404(thread_id)
    if row["locked"] and not is_admin():
        flash("Este tema está cerrado.", "error")
        return redirect(url_for("board.thread", thread_id=thread_id))

    body = request.form.get("body", "").strip()[:BODY_MAX]
    if not body:
        flash("El comentario no puede estar vacío.", "error")
        return redirect(url_for("board.thread", thread_id=thread_id))
    wait = cooldown_remaining()
    if wait:
        flash(f"Espera {wait} segundos antes de comentar otra vez.", "error")
        return redirect(url_for("board.thread", thread_id=thread_id))

    get_db().execute(
        "INSERT INTO comments (thread_id, author_id, body_md) VALUES (?, ?, ?)",
        (thread_id, g.member["id"], body),
    )
    return redirect(url_for("board.thread", thread_id=thread_id) + "#final")


@bp.route("/comentario/<int:comment_id>/editar", methods=["GET", "POST"])
@login_required
def edit_comment(comment_id: int):
    row = _comment_or_404(comment_id)
    if not may_edit(row):
        abort(403)
    if request.method == "GET":
        return render_template("comment_form.html", comment=row)

    body = request.form.get("body", "").strip()[:BODY_MAX]
    if not body:
        flash("El comentario no puede estar vacío.", "error")
        return redirect(url_for("board.edit_comment", comment_id=comment_id))
    get_db().execute(
        "UPDATE comments SET body_md = ?, edited_at = datetime('now') WHERE id = ?",
        (body, comment_id),
    )
    return redirect(url_for("board.thread", thread_id=row["thread_id"]))


@bp.route("/comentario/<int:comment_id>/eliminar", methods=["POST"])
@login_required
def delete_comment(comment_id: int):
    row = _comment_or_404(comment_id)
    if not may_delete(row):
        abort(403)
    get_db().execute("UPDATE comments SET deleted_at = datetime('now') WHERE id = ?", (comment_id,))
    flash("Comentario eliminado.", "ok")
    return redirect(url_for("board.thread", thread_id=row["thread_id"]))


@bp.route("/tema/<int:thread_id>/estado", methods=["POST"])
@admin_required
def set_state(thread_id: int):
    _thread_or_404(thread_id)
    field = request.form.get("field")
    if field not in ("pinned", "locked"):
        abort(400, "Campo desconocido.")
    value = 1 if request.form.get("value") == "1" else 0
    # `field` is checked against a fixed pair above, so it never carries
    # anything a member typed into the statement.
    get_db().execute(f"UPDATE threads SET {field} = ? WHERE id = ?", (value, thread_id))
    return redirect(url_for("board.thread", thread_id=thread_id))