import { useEffect, useRef, useState } from "react";
import { Plus, Trash2, Eye, EyeOff, Table, FileText } from "lucide-react";
import { Button, Input } from "@/components/ui";

interface Row {
  /** Stable across edits, so deleting a row doesn't shift the reveal state
   *  (or input focus) onto its neighbour. */
  id: string;
  key: string;
  value: string;
}

const SENSITIVE_RE = /(PASS|SECRET|TOKEN|KEY|APIKEY|PWD|CREDENTIAL)/i;

let nextRowId = 0;
const newRow = (key = "", value = ""): Row => ({ id: `r${nextRowId++}`, key, value });

function parseEnv(text: string): Row[] {
  return text
    .split("\n")
    .filter((l) => l.trim() && !l.trim().startsWith("#") && l.includes("="))
    .map((l) => {
      const idx = l.indexOf("=");
      return newRow(l.slice(0, idx).trim(), l.slice(idx + 1));
    });
}

function serialize(rows: Row[]): string {
  const named = rows.filter((r) => r.key.trim());
  return named.map((r) => `${r.key.trim()}=${r.value}`).join("\n") + (named.length ? "\n" : "");
}

const QUICK = [
  { key: "PUID", value: "1000" },
  { key: "PGID", value: "1000" },
  { key: "TZ", value: "Europe/Berlin" },
];

export function EnvEditor({
  value,
  onChange,
}: {
  value: string;
  onChange: (v: string) => void;
}) {
  const [mode, setMode] = useState<"table" | "raw">("table");
  const [reveal, setReveal] = useState<Record<string, boolean>>({});

  // The rows are owned here rather than derived from `value` on every render:
  // serialize() drops rows with an empty key, so a freshly added (still blank)
  // row would be thrown away before it could ever be typed into — which is why
  // "Add variable" appeared to do nothing.
  const [rows, setRows] = useState<Row[]>(() => parseEnv(value));
  const lastEmitted = useRef(value);

  useEffect(() => {
    // Only re-parse when `value` changed somewhere else (loading a stack,
    // editing in raw mode); echoes of our own edits must not clobber blank rows.
    if (value !== lastEmitted.current) {
      lastEmitted.current = value;
      setRows(parseEnv(value));
    }
  }, [value]);

  const update = (next: Row[]) => {
    setRows(next);
    const text = serialize(next);
    lastEmitted.current = text;
    onChange(text);
  };

  const setRow = (id: string, patch: Partial<Row>) =>
    update(rows.map((r) => (r.id === id ? { ...r, ...patch } : r)));
  const addRow = (row?: { key: string; value: string }) =>
    update([...rows, row ? newRow(row.key, row.value) : newRow()]);
  const delRow = (id: string) => update(rows.filter((r) => r.id !== id));

  const tabClass = (active: boolean) =>
    active
      ? "flex items-center gap-1 rounded bg-accent px-2 py-1 text-xs text-white dark:bg-accent-dark dark:text-slate-900"
      : "flex items-center gap-1 rounded border border-slate-300 px-2 py-1 text-xs dark:border-slate-600";

  return (
    <div className="flex h-full min-h-0 flex-col">
      <div className="mb-2 flex items-center gap-2">
        <button onClick={() => setMode("table")} className={tabClass(mode === "table")}>
          <Table className="h-3.5 w-3.5" /> Table
        </button>
        <button onClick={() => setMode("raw")} className={tabClass(mode === "raw")}>
          <FileText className="h-3.5 w-3.5" /> Raw
        </button>
        {mode === "table" && (
          <div className="ml-auto flex gap-1">
            {QUICK.map((q) => (
              <button
                key={q.key}
                onClick={() => addRow(q)}
                className="rounded border border-slate-300 px-2 py-1 text-xs hover:bg-slate-100 dark:border-slate-600 dark:hover:bg-slate-700"
              >
                + {q.key}
              </button>
            ))}
          </div>
        )}
      </div>

      {mode === "raw" ? (
        <textarea
          value={value}
          onChange={(e) => onChange(e.target.value)}
          spellCheck={false}
          // min-h-0 lets flex-1 shrink it past a textarea's intrinsic two-row
          // height, so it fills the pane instead of dictating it.
          className="min-h-0 flex-1 resize-none rounded-lg border border-slate-300 bg-white p-3 font-mono text-xs dark:border-slate-600 dark:bg-slate-800"
          placeholder="KEY=value"
        />
      ) : (
        <div className="flex min-h-0 flex-1 flex-col">
          <div className="min-h-0 flex-1 overflow-auto">
            <table className="w-full text-sm">
              <thead className="text-left text-xs text-slate-500">
                <tr>
                  <th className="pb-1">Key</th>
                  <th className="pb-1">Value</th>
                  <th className="w-10 pb-1" />
                </tr>
              </thead>
              <tbody>
                {rows.map((r) => {
                  const sensitive = SENSITIVE_RE.test(r.key);
                  const masked = sensitive && !reveal[r.id];
                  return (
                    <tr key={r.id}>
                      <td className="py-1 pr-2">
                        <Input
                          value={r.key}
                          onChange={(e) => setRow(r.id, { key: e.target.value })}
                          placeholder="KEY"
                        />
                      </td>
                      <td className="py-1 pr-2">
                        <div className="flex items-center gap-1">
                          <Input
                            type={masked ? "password" : "text"}
                            value={r.value}
                            onChange={(e) => setRow(r.id, { value: e.target.value })}
                            placeholder="value"
                          />
                          {sensitive && (
                            <button
                              onClick={() => setReveal((s) => ({ ...s, [r.id]: !s[r.id] }))}
                              className="rounded p-1.5 text-slate-400 hover:bg-slate-100 dark:hover:bg-slate-700"
                              title={masked ? "Reveal" : "Hide"}
                            >
                              {masked ? <Eye className="h-4 w-4" /> : <EyeOff className="h-4 w-4" />}
                            </button>
                          )}
                        </div>
                      </td>
                      <td className="py-1">
                        <button
                          onClick={() => delRow(r.id)}
                          className="rounded p-1.5 text-red-500 hover:bg-slate-100 dark:hover:bg-slate-700"
                          title="Remove variable"
                        >
                          <Trash2 className="h-4 w-4" />
                        </button>
                      </td>
                    </tr>
                  );
                })}
              </tbody>
            </table>
            {rows.length === 0 && (
              <p className="py-3 text-sm text-slate-500">
                No variables yet — “Add variable” starts a blank row.
              </p>
            )}
          </div>
          {/* Outside the scroll area: with a long list the button would
              otherwise sit below the fold. */}
          <Button variant="outline" className="mt-2 self-start" onClick={() => addRow()}>
            <Plus className="h-4 w-4" /> Add variable
          </Button>
        </div>
      )}
    </div>
  );
}