"""
app/admin/audit_log/routes.py
Audit log viewer: filterable by actor, action prefix, date range.
CSV export. Append-only — no modifications permitted.
"""

import csv
import io
import logging
from datetime import datetime, timezone

from flask import Blueprint, render_template, request, Response
from flask_login import login_required

from app.models.platform import AuditLog, SystemUser
from app.admin.utils import superadmin_required

logger = logging.getLogger(__name__)

audit_log_bp = Blueprint("audit_log", __name__, url_prefix="/audit-log")
_PAGE_SIZE = 50


@audit_log_bp.route("/")
@login_required
@superadmin_required
def index():
    actor_id = request.args.get("actor_id", type=int)
    action_prefix = request.args.get("action", "").strip()
    target_type = request.args.get("target_type", "").strip()
    date_from_raw = request.args.get("date_from", "").strip()
    date_to_raw = request.args.get("date_to", "").strip()
    page = request.args.get("page", 1, type=int)

    q = AuditLog.query.order_by(AuditLog.created_at.desc())

    if actor_id:
        q = q.filter_by(actor_id=actor_id)
    if action_prefix:
        q = q.filter(AuditLog.action.startswith(action_prefix))
    if target_type:
        q = q.filter_by(target_type=target_type)
    if date_from_raw:
        try:
            q = q.filter(AuditLog.created_at >= datetime.fromisoformat(date_from_raw))
        except ValueError:
            pass
    if date_to_raw:
        try:
            q = q.filter(AuditLog.created_at <= datetime.fromisoformat(date_to_raw))
        except ValueError:
            pass

    pagination = q.paginate(page=page, per_page=_PAGE_SIZE, error_out=False)
    system_users = SystemUser.query.order_by(SystemUser.name).all()

    return render_template(
        "admin/audit_log/index.html",
        pagination=pagination,
        entries=pagination.items,
        system_users=system_users,
        filters={
            "actor_id": actor_id, "action": action_prefix,
            "target_type": target_type, "date_from": date_from_raw, "date_to": date_to_raw,
        },
    )


@audit_log_bp.route("/export.csv")
@login_required
@superadmin_required
def export_csv():
    """Export filtered audit log as CSV (max 10,000 rows)."""
    actor_id = request.args.get("actor_id", type=int)
    action_prefix = request.args.get("action", "").strip()
    target_type = request.args.get("target_type", "").strip()
    date_from_raw = request.args.get("date_from", "").strip()
    date_to_raw = request.args.get("date_to", "").strip()

    q = AuditLog.query.order_by(AuditLog.created_at.desc())
    if actor_id:
        q = q.filter_by(actor_id=actor_id)
    if action_prefix:
        q = q.filter(AuditLog.action.startswith(action_prefix))
    if target_type:
        q = q.filter_by(target_type=target_type)
    if date_from_raw:
        try:
            q = q.filter(AuditLog.created_at >= datetime.fromisoformat(date_from_raw))
        except ValueError:
            pass
    if date_to_raw:
        try:
            q = q.filter(AuditLog.created_at <= datetime.fromisoformat(date_to_raw))
        except ValueError:
            pass

    entries = q.limit(10000).all()

    output = io.StringIO()
    writer = csv.writer(output)
    writer.writerow([
        "id", "created_at", "actor_id", "actor_type", "action",
        "target_type", "target_id", "ip_address",
    ])
    for e in entries:
        writer.writerow([
            e.id, e.created_at, e.actor_id, e.actor_type, e.action,
            e.target_type, e.target_id, e.ip_address,
        ])

    logger.info("Audit log exported: %d rows", len(entries))
    return Response(
        output.getvalue(),
        mimetype="text/csv",
        headers={"Content-Disposition": "attachment; filename=audit_log.csv"},
    )