import clsx from "clsx";
import { useEffect, useMemo, useState } from "react";
import { useTranslation } from "react-i18next";
import { Copy, Search } from "lucide-react";

import { copyText } from "../lib/clipboard";
import {
  clear,
  events,
  LEVEL_GROUPS,
  subscribe,
  type LevelGroup as Filter,
  type LogEvent,
} from "../lib/log";
import { notify } from "../lib/notifications";
import LogLine from "./LogLine";
import NavGrid from "./ui/NavGrid";
import { Button } from "./ui/Button";
import FilterChipGroup from "./ui/FilterChipGroup";
import { InnerInput } from "./ui/Input";
import { fieldClass } from "./ui/fieldStyles";

// Rows rendered at once. The ring holds up to 2000 events; drawing all of them on every new event
// would make the settings page the slowest thing in the app while it is watching the app.
const ROWS_SHOWN = 500;

/** The ring, live: re-read at most once per animation frame however fast events arrive. */
function useLogEvents(): LogEvent[] {
  const [list, setList] = useState(events);
  useEffect(() => {
    let frame: number | null = null;
    const unsubscribe = subscribe(() => {
      if (frame !== null) return;
      frame = window.requestAnimationFrame(() => {
        frame = null;
        setList(events());
      });
    });
    // eslint-disable-next-line react-hooks/set-state-in-effect -- this IS the subscribe-to-an-external-store shape the rule's own text allows: the ring fills outside React, and a sync at subscribe time is what closes the gap between the first render and the listener. useSyncExternalStore would drop the rAF coalescing, which is the point at a few hundred events a second.
    setList(events()); // whatever arrived between the first render and the subscription
    return () => {
      unsubscribe();
      if (frame !== null) window.cancelAnimationFrame(frame);
    };
  }, []);
  return list;
}

// A row's React key: the event OBJECT's own number, handed out the first time it is drawn. The ring
// keeps the same objects, so the key stays put as the list grows at the top — an index key shifted
// every row on every new event, remounting all of them and dropping the focus off the row button
// (at Részletes a click on a row logs a line itself, so it happened on every click).
const rowIds = new WeakMap<LogEvent, number>();
let nextRowId = 0;
const rowKey = (event: LogEvent) => {
  let id = rowIds.get(event);
  if (id === undefined) {
    id = nextRowId++;
    rowIds.set(event, id);
  }
  return id;
};

const matches = (event: LogEvent, needle: string) =>
  !needle ||
  [event.event, event.msg, event.request_id ?? "", event.attrs ? JSON.stringify(event.attrs) : ""]
    .join(" ")
    .toLowerCase()
    .includes(needle);

// "Saját napló" — this tab's own client log (lib/log.ts), exactly what it would send while a raised
// diagnostics level is on: newest first, filtered by level group and free text, a row opens to its
// correlation id and attributes, and "Copy" puts the FILTERED events on the clipboard as JSON lines
// (one event per line) for a bug report.
export default function MyLogViewer() {
  const { t } = useTranslation();
  const all = useLogEvents();
  const [filter, setFilter] = useState<Filter>("all");
  const [query, setQuery] = useState("");
  const [open, setOpen] = useState<LogEvent | null>(null);

  const counts = useMemo(() => {
    const out: Record<Filter, number> = {
      all: all.length,
      error: 0,
      warning: 0,
      info: 0,
      detail: 0,
    };
    for (const e of all) {
      for (const [group, levels] of Object.entries(LEVEL_GROUPS)) {
        if (levels.includes(e.level)) out[group as Filter] += 1;
      }
    }
    return out;
  }, [all]);

  const shown = useMemo(() => {
    const needle = query.trim().toLowerCase();
    const levels = filter === "all" ? null : LEVEL_GROUPS[filter];
    const out: LogEvent[] = [];
    for (let i = all.length - 1; i >= 0; i--) {
      const e = all[i]!;
      if ((!levels || levels.includes(e.level)) && matches(e, needle)) out.push(e);
    }
    return out;
  }, [all, filter, query]);

  const copy = async () => {
    // Oldest first, as a log reads — the list shows newest first only for watching it live.
    const text = [...shown]
      .reverse()
      .map((e) => JSON.stringify(e))
      .join("\n");
    const ok = await copyText(text);
    notify(
      ok
        ? { level: "success", message: t("settings.myLog.copied", { count: shown.length }) }
        : { level: "error", message: t("settings.myLog.copyFailed") },
    );
  };

  const filters: readonly Filter[] = ["all", "error", "warning", "info", "detail"];

  return (
    <div data-testid="my-log" className="overflow-hidden rounded-xl border border-border bg-bg">
      <p className="px-3 pt-2 text-xs text-muted">{t("settings.myLog.hint")}</p>
      <div className="flex flex-wrap items-center gap-2 border-b border-border p-2">
        <label
          className={clsx(
            fieldClass({ size: "sm", pill: true }),
            "flex min-w-[10rem] flex-1 items-center gap-1.5",
          )}
        >
          <Search className="h-3.5 w-3.5 shrink-0 text-muted" aria-hidden />
          <InnerInput
            type="search"
            value={query}
            onChange={(e) => setQuery(e.target.value)}
            placeholder={t("settings.myLog.search")}
            aria-label={t("settings.myLog.search")}
          />
        </label>
        <FilterChipGroup
          ariaLabel={t("settings.myLog.filterLabel")}
          value={filter}
          onChange={setFilter}
          options={filters.map((f) => ({
            value: f,
            label: t(`settings.myLog.filters.${f}`),
            count: counts[f],
          }))}
        />
      </div>

      <div className="max-h-96 overflow-auto font-mono text-2xs" data-testid="my-log-lines">
        {shown.length === 0 ? (
          <p className="px-3 py-6 text-center font-sans text-sm text-muted">
            {all.length === 0 ? t("settings.myLog.emptyAll") : t("settings.myLog.empty")}
          </p>
        ) : (
          <NavGrid>
            {shown.slice(0, ROWS_SHOWN).map((e, index) => (
              <LogLine
                navIndex={index}
                key={rowKey(e)}
                ts={e.ts}
                level={e.level}
                event={e.event}
                msg={e.msg}
                open={open === e}
                onToggle={() => setOpen(open === e ? null : e)}
              >
                <pre className="overflow-x-auto whitespace-pre">
                  {JSON.stringify(
                    {
                      event: e.event,
                      msg: e.msg,
                      request_id: e.request_id,
                      ts: e.ts,
                      tab_id: e.tab_id,
                      attrs: e.attrs,
                    },
                    null,
                    2,
                  )}
                </pre>
              </LogLine>
            ))}
          </NavGrid>
        )}
      </div>

      <div className="flex flex-wrap items-center justify-between gap-2 border-t border-border px-3 py-1.5 text-xs text-muted">
        <span>
          {t("settings.myLog.count", { count: all.length })}
          {shown.length > ROWS_SHOWN &&
            ` · ${t("settings.myLog.capped", { shown: ROWS_SHOWN, count: shown.length })}`}
        </span>
        <span className="flex gap-1.5">
          <Button
            variant="outline"
            size="xs"
            icon={<Copy className="h-3.5 w-3.5" />}
            disabled={shown.length === 0}
            onClick={() => void copy()}
          >
            {t("settings.myLog.copy")}
          </Button>
          <Button
            variant="outline"
            size="xs"
            disabled={all.length === 0}
            onClick={() => {
              clear();
              setOpen(null);
            }}
          >
            {t("settings.myLog.clear")}
          </Button>
        </span>
      </div>
    </div>
  );
}