/**
 * @file QueryExplorer.tsx
 * @description `/query`: filter sessions, events or agents (free text, AI tool,
 * status, local date range, folder subtree, plus the global data scope), sort
 * by a column the server allows, page through the rows, and export the whole
 * filtered set as CSV or JSON (`GET /api/query`, capped server-side).
 * @author Nguyễn Ngọc Trí Vĩ <vinnt@smartgift.vn>
 */

import { useEffect, useMemo, useState } from "react";
import { Link } from "react-router-dom";
import { useTranslation } from "react-i18next";
import { ArrowDown, ArrowUp, ChevronLeft, ChevronRight, Download, RotateCcw } from "lucide-react";
import { api } from "../lib/api";
import { applyRange } from "../lib/dateRange";
import { useDataScope } from "../lib/dataScope";
import { useAiTools } from "../hooks/useAiTools";
import { Select } from "../components/Select";
import type { QueryEntity, QueryPage } from "../lib/types";

const PAGE_SIZE = 50;
const ENTITIES: QueryEntity[] = ["sessions", "events", "agents"];
const STATUSES: Record<QueryEntity, string[]> = {
  sessions: ["active", "completed", "error", "abandoned"],
  events: [],
  agents: ["working", "waiting", "completed", "error"],
};

export function QueryExplorer() {
  const { t } = useTranslation("analytics");
  const aiTools = useAiTools();
  const [scope] = useDataScope();
  const [entity, setEntity] = useState<QueryEntity>("sessions");
  const [q, setQ] = useState("");
  const [cwd, setCwd] = useState("");
  const [typed, setTyped] = useState({ q: "", cwd: "" });
  const [tool, setTool] = useState("");
  const [status, setStatus] = useState("");
  const [from, setFrom] = useState("");
  const [to, setTo] = useState("");
  const [sort, setSort] = useState("");
  const [dir, setDir] = useState<"asc" | "desc">("desc");
  const [offset, setOffset] = useState(0);
  const [page, setPage] = useState<QueryPage | null>(null);
  const [error, setError] = useState<string | null>(null);

  // Text filters wait for a pause in typing.
  useEffect(() => {
    const h = setTimeout(() => {
      const next = { q: q.trim(), cwd: cwd.trim() };
      setTyped((prev) => (prev.q === next.q && prev.cwd === next.cwd ? prev : next));
      setOffset(0);
    }, 300);
    return () => clearTimeout(h);
  }, [q, cwd]);

  /** Every filter change starts over at the first page. */
  const fresh =
    <T,>(set: (v: T) => void) =>
    (v: T) => {
      set(v);
      setOffset(0);
    };

  const filters = useMemo(() => {
    const p = new URLSearchParams({ entity });
    if (typed.q) p.set("q", typed.q);
    if (typed.cwd) p.set("cwd", typed.cwd);
    if (tool) p.set("tool", tool);
    if (status) p.set("status", status);
    if (sort) {
      p.set("sort", sort);
      p.set("dir", dir);
    }
    return applyRange(p, { from: from || undefined, to: to || undefined });
  }, [entity, typed, tool, status, sort, dir, from, to]);

  useEffect(() => {
    let live = true;
    const p = new URLSearchParams(filters);
    p.set("limit", String(PAGE_SIZE));
    p.set("offset", String(offset));
    api.query
      .page(p)
      .then((r) => {
        if (!live) return;
        setPage(r);
        setError(null);
      })
      .catch((err) => live && setError(err instanceof Error ? err.message : String(err)));
    return () => {
      live = false;
    };
  }, [filters, offset, scope]);

  const switchEntity = (v: QueryEntity) => {
    setEntity(v);
    setStatus("");
    setSort("");
    setDir("desc");
    setOffset(0);
    setPage(null);
  };
  const reset = () => {
    setQ("");
    setCwd("");
    setTool("");
    setStatus("");
    setFrom("");
    setTo("");
    setSort("");
    setDir("desc");
    setOffset(0);
  };
  const sortedBy = sort || page?.sortable[0] || "";
  // A click on the current column flips it; another column starts descending.
  const sortOn = (col: string) => {
    setDir(col === sortedBy && dir === "desc" ? "asc" : "desc");
    setSort(col);
    setOffset(0);
  };

  const total = page?.total ?? 0;
  const cap = page?.export_cap ?? 50_000;
  const statuses = STATUSES[entity];

  return (
    <div className="animate-fade-in space-y-5">
      <div>
        <h1 className="text-lg font-semibold text-fg-primary">{t("query.title")}</h1>
        <p className="text-sm text-fg-muted">{t("query.subtitle")}</p>
      </div>

      <div className="card p-4 flex flex-wrap items-end gap-3">
        <div className="w-36">
          <Select
            value={entity}
            onChange={switchEntity}
            label={t("query.entity")}
            options={ENTITIES.map((v) => ({ value: v, label: t(`query.entities.${v}`) }))}
          />
        </div>
        <input
          className="input text-sm w-56"
          value={q}
          onChange={(e) => setQ(e.target.value)}
          placeholder={t("query.searchPlaceholder")}
          aria-label={t("query.search")}
        />
        <div className="w-40">
          <Select
            value={tool}
            onChange={fresh(setTool)}
            label={t("toolFilter")}
            options={[
              { value: "", label: t("allTools") },
              ...aiTools.tools.map((x) => ({ value: x.id, label: x.label })),
            ]}
          />
        </div>
        {statuses.length > 0 && (
          <div className="w-40">
            <Select
              value={status}
              onChange={fresh(setStatus)}
              label={t("query.status")}
              options={[
                { value: "", label: t("query.allStatuses") },
                ...statuses.map((s) => ({ value: s, label: t(`common:status.${s}`) })),
              ]}
            />
          </div>
        )}
        <input
          type="date"
          className="input text-sm"
          value={from}
          max={to || undefined}
          onChange={(e) => fresh(setFrom)(e.target.value)}
          aria-label={t("query.from")}
          title={t("query.from")}
        />
        <input
          type="date"
          className="input text-sm"
          value={to}
          min={from || undefined}
          onChange={(e) => fresh(setTo)(e.target.value)}
          aria-label={t("query.to")}
          title={t("query.to")}
        />
        <input
          className="input text-sm w-56 font-mono"
          value={cwd}
          onChange={(e) => setCwd(e.target.value)}
          placeholder={t("query.cwdPlaceholder")}
          aria-label={t("query.cwd")}
          title={t("query.cwd")}
        />
        <button type="button" className="btn-ghost" onClick={reset} title={t("query.reset")}>
          <RotateCcw className="w-4 h-4" />
          {t("query.reset")}
        </button>
      </div>

      <div className="flex flex-wrap items-center justify-between gap-3">
        <p className="text-xs text-fg-muted">
          {total > cap
            ? t("query.exportTruncated", {
                total: total.toLocaleString(),
                cap: cap.toLocaleString(),
              })
            : t("query.exportNote", { cap: cap.toLocaleString() })}
        </p>
        <div className="flex items-center gap-2">
          <a className="btn-ghost" href={api.query.exportUrl(filters, "csv")} download>
            <Download className="w-4 h-4" />
            {t("query.exportCsv")}
          </a>
          <a className="btn-ghost" href={api.query.exportUrl(filters, "json")} download>
            <Download className="w-4 h-4" />
            {t("query.exportJson")}
          </a>
        </div>
      </div>

      {error && (
        <p role="alert" className="text-sm text-status-danger">
          {error}
        </p>
      )}

      {page && page.rows.length === 0 ? (
        <p className="py-10 text-center text-sm text-fg-muted">{t("query.empty")}</p>
      ) : (
        page && (
          <div className="card overflow-x-auto">
            <table className="w-full text-sm" data-testid="query-table">
              <thead>
                <tr className="border-b border-border text-left">
                  {page.columns.map((c) => {
                    const sortable = page.sortable.includes(c);
                    return (
                      <th
                        key={c}
                        className="px-3 py-2 text-[11px] font-semibold text-fg-muted font-mono"
                        aria-sort={
                          c === sortedBy ? (dir === "asc" ? "ascending" : "descending") : undefined
                        }
                      >
                        {sortable ? (
                          <button
                            type="button"
                            onClick={() => sortOn(c)}
                            className="inline-flex items-center gap-1 hover:text-fg-primary"
                            title={t("query.sortBy", { column: c })}
                          >
                            {c}
                            {c === sortedBy &&
                              (dir === "asc" ? (
                                <ArrowUp className="w-3 h-3" />
                              ) : (
                                <ArrowDown className="w-3 h-3" />
                              ))}
                          </button>
                        ) : (
                          c
                        )}
                      </th>
                    );
                  })}
                </tr>
              </thead>
              <tbody className="divide-y divide-border">
                {page.rows.map((r, i) => (
                  <tr key={`${r.id}-${i}`} className="hover:bg-surface-4">
                    {page.columns.map((c) => {
                      const v = r[c];
                      const sid =
                        (entity === "sessions" && c === "id") || c === "session_id" ? v : null;
                      return (
                        <td
                          key={c}
                          className="px-3 py-1.5 max-w-[22rem] truncate text-fg-secondary"
                          title={v == null ? undefined : String(v)}
                        >
                          {sid ? (
                            <Link
                              to={`/sessions/${encodeURIComponent(String(sid))}`}
                              className="font-mono text-accent hover:underline"
                            >
                              {String(sid).slice(0, 8)}
                            </Link>
                          ) : (
                            (v ?? "")
                          )}
                        </td>
                      );
                    })}
                  </tr>
                ))}
              </tbody>
            </table>
          </div>
        )
      )}

      {page && total > 0 && (
        <div className="flex items-center justify-end gap-2 text-xs text-fg-muted">
          <span>
            {t("query.rows", {
              from: (offset + 1).toLocaleString(),
              to: Math.min(offset + PAGE_SIZE, total).toLocaleString(),
              total: total.toLocaleString(),
            })}
          </span>
          <button
            type="button"
            className="btn-ghost"
            disabled={offset === 0}
            onClick={() => setOffset(Math.max(0, offset - PAGE_SIZE))}
            title={t("query.prev")}
            aria-label={t("query.prev")}
          >
            <ChevronLeft className="w-4 h-4" />
          </button>
          <button
            type="button"
            className="btn-ghost"
            disabled={offset + PAGE_SIZE >= total}
            onClick={() => setOffset(offset + PAGE_SIZE)}
            title={t("query.next")}
            aria-label={t("query.next")}
          >
            <ChevronRight className="w-4 h-4" />
          </button>
        </div>
      )}
    </div>
  );
}