import { useMemo, useState } from "react";
import { X, Table as TableIcon, FileText } from "lucide-react";
import type { EmbedDataFile } from "../editor/embeds/embed-data-store";
import { formatBytes } from "../utils/data-files";

interface DataFileViewerProps {
  file: EmbedDataFile;
  onClose: () => void;
}

const MAX_PREVIEW_ROWS = 100;

function splitCsvLine(line: string, delim: string): string[] {
  const out: string[] = [];
  let cur = "";
  let inQuotes = false;
  for (let i = 0; i < line.length; i++) {
    const c = line[i];
    if (inQuotes) {
      if (c === '"') {
        if (line[i + 1] === '"') {
          cur += '"';
          i++;
        } else {
          inQuotes = false;
        }
      } else {
        cur += c;
      }
    } else if (c === '"') {
      inQuotes = true;
    } else if (c === delim) {
      out.push(cur);
      cur = "";
    } else {
      cur += c;
    }
  }
  out.push(cur);
  return out;
}

function parseTable(content: string, delim: string, maxRows: number): {
  columns: string[];
  rows: string[][];
  total: number;
} {
  const lines = content.split(/\r\n|\n|\r/).filter((l) => l.length > 0);
  if (lines.length === 0) return { columns: [], rows: [], total: 0 };
  const columns = splitCsvLine(lines[0], delim);
  const rows = lines
    .slice(1, 1 + maxRows)
    .map((l) => splitCsvLine(l, delim));
  return { columns, rows, total: Math.max(0, lines.length - 1) };
}

function prettyJson(content: string): string {
  try {
    return JSON.stringify(JSON.parse(content), null, 2);
  } catch {
    return content;
  }
}

export function DataFileViewer({ file, onClose }: DataFileViewerProps) {
  const { ext } = file.meta;
  const isTabular = ext === "csv" || ext === "tsv";
  const [mode, setMode] = useState<"table" | "raw">(isTabular ? "table" : "raw");

  const parsed = useMemo(() => {
    if (!isTabular) return null;
    return parseTable(file.content, ext === "tsv" ? "\t" : ",", MAX_PREVIEW_ROWS);
  }, [file.content, ext, isTabular]);

  const raw = useMemo(() => {
    if (ext === "json") return prettyJson(file.content);
    return file.content;
  }, [file.content, ext]);

  return (
    <div className="es-data-viewer">
      <div className="es-data-viewer__header">
        <div className="es-data-viewer__title">
          <strong>{file.meta.name}</strong>
          <span className="es-data-viewer__meta">
            {ext.toUpperCase()} - {formatBytes(file.meta.size)}
            {file.meta.rowCount !== undefined ? ` - ${file.meta.rowCount} rows` : ""}
          </span>
        </div>
        <div className="es-data-viewer__actions">
          {isTabular && (
            <div className="es-data-viewer__tabs">
              <button
                type="button"
                className={`es-preview__tab ${mode === "table" ? "es-preview__tab--active" : ""}`}
                onClick={() => setMode("table")}
              >
                <TableIcon size={12} />
                Table
              </button>
              <button
                type="button"
                className={`es-preview__tab ${mode === "raw" ? "es-preview__tab--active" : ""}`}
                onClick={() => setMode("raw")}
              >
                <FileText size={12} />
                Raw
              </button>
            </div>
          )}
          <button
            type="button"
            className="embed-btn"
            onClick={onClose}
            aria-label="Close file viewer"
          >
            <X size={14} />
          </button>
        </div>
      </div>

      <div className="es-data-viewer__body">
        {isTabular && mode === "table" && parsed ? (
          <div className="es-data-table-wrap">
            <table className="es-data-table">
              <thead>
                <tr>
                  {parsed.columns.map((col, i) => (
                    <th key={i}>{col}</th>
                  ))}
                </tr>
              </thead>
              <tbody>
                {parsed.rows.map((row, ri) => (
                  <tr key={ri}>
                    {parsed.columns.map((_, ci) => (
                      <td key={ci}>{row[ci] ?? ""}</td>
                    ))}
                  </tr>
                ))}
              </tbody>
            </table>
            {parsed.total > parsed.rows.length && (
              <div className="es-data-table__footer">
                Showing first {parsed.rows.length} of {parsed.total} rows
              </div>
            )}
          </div>
        ) : (
          <pre className="es-data-viewer__raw">
            <code>{raw}</code>
          </pre>
        )}
      </div>
    </div>
  );
}