import { useEffect, useMemo, useRef, useState } from "react";
import { toast } from "../dialogs";
import { useT } from "../i18n";
import { navigate } from "../router";
import { fill, loadTemplates, placeholders, type Template, type TemplateLists } from "../templates";
import { Icon } from "./Icon";

/** Choose a prompt template, fill its placeholders, return the text. */
export function TemplatePicker({ onPick, onClose }: { onPick: (text: string) => void; onClose: () => void }) {
  const t = useT();
  const [lists, setLists] = useState<TemplateLists>();
  const [q, setQ] = useState("");
  const [active, setActive] = useState(0);
  const [chosen, setChosen] = useState<Template>();
  const [values, setValues] = useState<Record<string, string>>({});
  const first = useRef<HTMLInputElement | HTMLTextAreaElement>(null);

  useEffect(() => {
    loadTemplates()
      .then(setLists)
      .catch((e) => (toast(e.message), onClose()));
    const h = (e: KeyboardEvent) => e.key === "Escape" && onClose();
    window.addEventListener("keydown", h);
    return () => window.removeEventListener("keydown", h);
    // eslint-disable-next-line react-hooks/exhaustive-deps
  }, []);

  const items = useMemo(() => {
    const all = [...(lists?.personal ?? []).map((x) => ({ ...x, global: false })), ...(lists?.global ?? []).map((x) => ({ ...x, global: true }))];
    const needle = q.trim().toLowerCase();
    return needle ? all.filter((x) => x.name.toLowerCase().includes(needle) || x.text.toLowerCase().includes(needle)) : all;
  }, [lists, q]);

  const choose = (tpl: Template) => {
    const ph = placeholders(tpl.text);
    if (!ph.length) return onPick(tpl.text);
    setChosen(tpl);
    setValues(Object.fromEntries(ph.map((p) => [p.name, ""])));
    setTimeout(() => first.current?.focus(), 0);
  };

  if (!lists) return null;
  const ph = chosen ? placeholders(chosen.text) : [];

  return (
    <div className="modal-backdrop" onClick={onClose}>
      <div className="modal tpl-picker" role="dialog" aria-label={t("templates.title")} onClick={(e) => e.stopPropagation()}>
        {!chosen ? (
          <>
            <h3>
              <Icon name="template" /> {t("templates.title")}
            </h3>
            <input
              autoFocus
              style={{ width: "100%" }}
              value={q}
              placeholder={t("templates.filter")}
              onChange={(e) => (setQ(e.target.value), setActive(0))}
              onKeyDown={(e) => {
                if (e.key === "ArrowDown") (e.preventDefault(), setActive((a) => Math.min(a + 1, items.length - 1)));
                if (e.key === "ArrowUp") (e.preventDefault(), setActive((a) => Math.max(a - 1, 0)));
                if (e.key === "Enter" && items[active]) (e.preventDefault(), choose(items[active]));
              }}
            />
            <div className="tpl-list">
              {items.length === 0 && (
                <div className="empty" style={{ padding: 16 }}>
                  {t("templates.none")}
                </div>
              )}
              {items.map((x, i) => (
                <button key={(x.global ? "g" : "p") + x.id} className={i === active ? "active" : ""} onClick={() => choose(x)} onMouseEnter={() => setActive(i)}>
                  <span className="tpl-name">
                    {x.name}
                    {x.global && <span className="chip">{t("templates.global")}</span>}
                  </span>
                  <span className="tpl-preview">{x.text.slice(0, 140)}</span>
                </button>
              ))}
            </div>
            <div className="row" style={{ marginTop: 12 }}>
              <button className="ghost small" onClick={() => (onClose(), navigate("/settings/templates"))}>
                <Icon name="edit" /> {t("templates.manage")}
              </button>
              <span className="grow" />
              <button onClick={onClose}>{t("common.cancel")}</button>
            </div>
          </>
        ) : (
          <form onSubmit={(e) => (e.preventDefault(), onPick(fill(chosen.text, values)))}>
            <h3>{chosen.name}</h3>
            {ph.map((p, i) => (
              <label key={p.name} className="tpl-field">
                <span>{p.name}</span>
                <textarea
                  ref={i === 0 ? (first as React.RefObject<HTMLTextAreaElement>) : undefined}
                  rows={2}
                  value={values[p.name] ?? ""}
                  placeholder={p.hint}
                  onChange={(e) => setValues({ ...values, [p.name]: e.target.value })}
                  onKeyDown={(e) => {
                    if (e.key === "Enter" && !e.shiftKey) {
                      e.preventDefault();
                      e.currentTarget.form?.requestSubmit();
                    }
                  }}
                />
              </label>
            ))}
            <div className="row" style={{ marginTop: 12, justifyContent: "flex-end" }}>
              <button type="button" onClick={() => setChosen(undefined)}>
                {t("common.back")}
              </button>
              <button type="submit" className="primary">
                {t("templates.insert")}
              </button>
            </div>
          </form>
        )}
      </div>
    </div>
  );
}