/**
 * @file RetentionSettings.tsx
 * @description Settings → Data → Session cleanup, under the manual purge: the
 * OPT-IN automatic cleanup (`AGENTHUB_RETENTION_DAYS`, 0 = off, the default)
 * that the hourly maintenance applies, the database's size and free space, and
 * **Compact now** — a full VACUUM behind a confirm, polled through
 * `GET /api/settings/retention` while it runs, then toasted. Backed by
 * `server/lib/db-retention.js`; a value the environment set is read-only.
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

import { useEffect, useState } from "react";
import { useTranslation } from "react-i18next";
import { AlertTriangle, Minimize2, RefreshCw } from "lucide-react";
import { api } from "../../lib/api";
import type { RetentionState } from "../../lib/api";
import { confirmDialog } from "../../lib/confirm";
import { formatBytes, formatDateTime } from "../../lib/format";
import { toast } from "../../lib/toast";

export function RetentionSettings() {
  const { t } = useTranslation("settings");
  const [state, setState] = useState<RetentionState | null>(null);
  const [days, setDays] = useState("0");
  const [saving, setSaving] = useState(false);

  useEffect(() => {
    api.settings.retention
      .get()
      .then((s) => {
        setState(s);
        setDays(String(s.days));
      })
      .catch(() => undefined);
  }, []);

  // A Compact takes a while on a large database: poll until it ends.
  const compacting = !!state?.compacting;
  useEffect(() => {
    if (!compacting) return;
    const id = window.setInterval(() => {
      api.settings.retention
        .get()
        .then((s) => {
          setState(s); // the draft keeps its value
          if (s.compacting || !s.last_compact) return;
          if (s.last_compact.ok) {
            toast.success(
              t("retention.compactDone", {
                before: formatBytes(s.last_compact.size_before ?? 0),
                after: formatBytes(s.last_compact.size_after ?? 0),
              })
            );
          } else {
            toast.error(t("retention.compactFailed", { error: s.last_compact.error }));
          }
        })
        .catch(() => undefined);
    }, 2000);
    return () => window.clearInterval(id);
  }, [compacting, t]);

  const max = state?.max_days ?? 3650;
  const n = Number(days);
  const valid = days.trim() !== "" && Number.isInteger(n) && n >= 0 && n <= max;
  const changed = state !== null && valid && n !== state.days;
  const owned = !!state?.env_owned.days;

  async function save() {
    setSaving(true);
    try {
      const s = await api.settings.retention.save(n);
      setState(s);
      setDays(String(s.days));
      toast.success(t("retention.saved"));
    } catch (err) {
      toast.error(err);
    } finally {
      setSaving(false);
    }
  }

  async function compact() {
    const ok = await confirmDialog({
      title: t("retention.compactConfirmTitle"),
      message: t("retention.compactConfirmBody"),
      confirmLabel: t("retention.compact"),
    });
    if (!ok) return;
    try {
      setState(await api.settings.retention.compact());
    } catch (err) {
      toast.error(err);
    }
  }

  const purged = state?.last_run?.retention?.purged_sessions;

  return (
    <div className="border-t border-border pt-4 space-y-3">
      <div>
        <h4 className="text-xs font-medium text-fg-secondary">{t("retention.title")}</h4>
        <p className="text-xs text-fg-muted">{t("retention.description")}</p>
      </div>
      <div className="flex flex-wrap items-end gap-3">
        <div className="bg-surface-2 rounded-lg px-4 py-3">
          <label htmlFor="retention-days" className="text-xs text-fg-secondary block mb-2">
            {t("retention.days")}
          </label>
          <div className="flex items-center gap-2">
            <input
              id="retention-days"
              type="number"
              min="0"
              max={max}
              step="1"
              inputMode="numeric"
              value={days}
              disabled={!state || owned}
              onChange={(e) => setDays(e.target.value)}
              aria-invalid={!valid || undefined}
              aria-describedby={!valid ? "retention-days-error" : undefined}
              className="input w-20 text-sm text-right font-mono"
            />
            <span className="text-xs text-fg-muted">{t("common:days")}</span>
          </div>
          {!valid && (
            <p id="retention-days-error" className="mt-1 text-[11px] text-status-danger">
              {t("retention.invalid", { max })}
            </p>
          )}
        </div>
        <button
          type="button"
          className="btn-primary px-4 py-2 text-sm disabled:opacity-50 disabled:cursor-not-allowed"
          disabled={saving || !changed || owned}
          onClick={() => void save()}
        >
          {saving ? t("homeDir.saving") : t("homeDir.save")}
        </button>
      </div>
      <p className="text-xs text-fg-secondary">
        {state && state.days > 0 ? t("retention.on", { days: state.days }) : t("retention.off")}
        {state?.last_run && purged !== undefined && (
          <> {t("retention.lastRun", { time: formatDateTime(state.last_run.at), n: purged })}</>
        )}
      </p>
      {owned && (
        <p className="text-xs text-status-warning flex items-start gap-1.5">
          <AlertTriangle className="w-3.5 h-3.5 flex-shrink-0 mt-px" />
          {t("privacy.envOwned")}
        </p>
      )}
      <div className="flex flex-wrap items-center gap-3">
        <button
          type="button"
          onClick={() => void compact()}
          disabled={!state || compacting}
          className="text-xs px-3 py-1.5 rounded-md transition-colors disabled:opacity-50 text-fg-secondary hover:text-fg-primary hover:bg-surface-4 border border-border"
        >
          {compacting ? (
            <RefreshCw className="w-3 h-3 animate-spin inline mr-1" />
          ) : (
            <Minimize2 className="w-3 h-3 inline mr-1" />
          )}
          {compacting ? t("retention.compacting") : t("retention.compact")}
        </button>
        {state?.space && (
          <span className="text-xs text-fg-muted">
            {t("retention.space", {
              size: formatBytes(state.db_size),
              free: formatBytes(state.space.free_bytes),
              mode: state.space.auto_vacuum,
            })}
          </span>
        )}
      </div>
    </div>
  );
}