import * as monaco from 'monaco-editor';

const SQL_LANG_ID = 'sql';

export const validateSql = (sql: string): Omit<monaco.editor.IMarker, 'owner' | 'resource'>[] => {
  const markers: Omit<monaco.editor.IMarker, 'owner' | 'resource'>[] = [];

  if (!sql || sql.trim().length === 0) {
    return markers;
  }

  // Basic SQL validation - check for common syntax issues
  const lines = sql.split('\n');

  lines.forEach((line, index) => {
    const lineNumber = index + 1;

    // Check for incomplete quotes
    const singleQuotes = (line.match(/'/g) || []).length;
    const doubleQuotes = (line.match(/"/g) || []).length;
    const backticks = (line.match(/`/g) || []).length;

    if (singleQuotes % 2 !== 0) {
      markers.push({
        severity: monaco.MarkerSeverity.Warning,
        startLineNumber: lineNumber,
        startColumn: 1,
        endLineNumber: lineNumber,
        endColumn: line.length + 1,
        message: "Unclosed single quote '",
        code: 'SQL001',
        source: SQL_LANG_ID,
      });
    }

    if (doubleQuotes % 2 !== 0) {
      markers.push({
        severity: monaco.MarkerSeverity.Warning,
        startLineNumber: lineNumber,
        startColumn: 1,
        endLineNumber: lineNumber,
        endColumn: line.length + 1,
        message: 'Unclosed double quote "',
        code: 'SQL002',
        source: SQL_LANG_ID,
      });
    }

    if (backticks % 2 !== 0) {
      markers.push({
        severity: monaco.MarkerSeverity.Warning,
        startLineNumber: lineNumber,
        startColumn: 1,
        endLineNumber: lineNumber,
        endColumn: line.length + 1,
        message: 'Unclosed backtick `',
        code: 'SQL003',
        source: SQL_LANG_ID,
      });
    }

    // Check for unmatched parentheses (basic check)
    const openParens = (line.match(/\(/g) || []).length;
    const closeParens = (line.match(/\)/g) || []).length;

    if (openParens > closeParens) {
      markers.push({
        severity: monaco.MarkerSeverity.Warning,
        startLineNumber: lineNumber,
        startColumn: 1,
        endLineNumber: lineNumber,
        endColumn: line.length + 1,
        message: 'Unmatched opening parenthesis',
        code: 'SQL004',
        source: SQL_LANG_ID,
      });
    } else if (closeParens > openParens) {
      markers.push({
        severity: monaco.MarkerSeverity.Warning,
        startLineNumber: lineNumber,
        startColumn: 1,
        endLineNumber: lineNumber,
        endColumn: line.length + 1,
        message: 'Unmatched closing parenthesis',
        code: 'SQL005',
        source: SQL_LANG_ID,
      });
    }
  });

  return markers;
};