import { SyntaxNode } from '@lezer/common';

import {
  Aggregate,
  And,
  AttributeField,
  ComparisonOp,
  FieldExpression,
  FieldOp,
  GroupOperation,
  Identifier,
  IntrinsicField,
  Or,
  Parent,
  parser,
  Pipe,
  Resource,
  ScalarExpression,
  ScalarFilter,
  SelectOperation,
  Span,
  SpansetFilter,
  SpansetPipelineExpression,
} from '@grafana/lezer-traceql';
import { monacoTypes } from '@grafana/ui';

/**
 * Given an error node, generate an error message to be displayed to the user.
 *
 * @param errorNode the error node, as returned by the TraceQL Lezer parser
 * @returns the error message
 */
export const computeErrorMessage = (errorNode: SyntaxNode) => {
  switch (errorNode.parent?.type.id) {
    case FieldExpression:
      switch (errorNode.prevSibling?.type.id) {
        case And:
        case Or:
          return 'Invalid value after logical operator.';
        case FieldOp:
          return 'Invalid value after comparison or arithmetic operator.';
        default:
          return 'Invalid operator after field expression.';
      }
    case SpansetFilter:
      if (errorNode.prevSibling?.type.id === FieldExpression) {
        return 'Invalid comparison operator after field expression.';
      }
      return 'Invalid expression for spanset.';
    case SpansetPipelineExpression:
      switch (errorNode.prevSibling?.type.id) {
        case SpansetPipelineExpression:
          return 'Invalid spanset combining operator after spanset expression.';
        case Pipe:
          return 'Invalid aggregation operator after pipepile operator.';
        default:
          return 'Invalid spanset expression after spanset combining operator.';
      }
    case IntrinsicField:
    case Aggregate:
      return 'Invalid expression for aggregator operator.';
    case GroupOperation:
      return 'Invalid expression for by operator.';
    case SelectOperation:
      return 'Invalid expression for select operator.';
    case AttributeField:
      return 'Invalid expression for spanset.';
    case ScalarFilter:
      switch (errorNode.prevSibling?.type.id) {
        case ComparisonOp:
          return 'Invalid value after comparison operator.';
        case ScalarExpression:
          if (errorNode.prevSibling?.firstChild?.type.id === Aggregate) {
            return 'Invalid comparison operator after aggregator operator.';
          }
        default:
          return 'Invalid value after comparison operator.';
      }
    default:
      return 'Invalid query.';
  }
};

/**
 * Parse the given query and find the error nodes, if any, in the resulting tree.
 *
 * @param query the TraceQL query of the user
 * @returns the error nodes
 */
export const getErrorNodes = (query: string): SyntaxNode[] => {
  // Return immediately if the query is empty, to avoid raising exceptions in processing it
  if (query.trim() === '') {
    return [];
  }

  // Check whether this is a trace ID or traceQL query by checking if it only contains hex characters
  const hexOnlyRegex = /^[0-9A-Fa-f]*$/;
  if (query.trim().match(hexOnlyRegex)) {
    return [];
  }

  const tree = parser.parse(query);

  // Find all error nodes and compute the associated erro boundaries
  const errorNodes: SyntaxNode[] = [];
  tree.iterate({
    enter: (nodeRef) => {
      if (nodeRef.type.id === 0) {
        errorNodes.push(nodeRef.node);
      }
    },
  });

  return errorNodes;
};

/**
 * Use red markers (squiggles) to highlight syntax errors in queries.
 *
 */
export const setMarkers = (
  monaco: typeof monacoTypes,
  model: monacoTypes.editor.ITextModel,
  errorNodes: SyntaxNode[]
) => {
  const markers = [
    ...getErrorMarkers(monaco.MarkerSeverity.Error, model, errorNodes),
    ...getWarningMarkers(monaco.MarkerSeverity.Warning, model),
  ];
  monaco.editor.setModelMarkers(
    model,
    'owner', // default value
    markers
  );
};

export const getErrorMarkers = (severity: number, model: monacoTypes.editor.ITextModel, errorNodes: SyntaxNode[]) => {
  return errorNodes.map((errorNode) => {
    const message = computeErrorMessage(errorNode);
    return getMarker(severity, message, model, errorNode.from, errorNode.to);
  });
};

export const getWarningMarkers = (severity: number, model: monacoTypes.editor.ITextModel) => {
  let markers = [];

  // Check if there are issues that should result in a warning marker
  const text = model.getValue();
  const tree = parser.parse(text);
  const indexOfDot = text.indexOf('.');
  if (indexOfDot > -1) {
    const cur = tree.cursorAt(0);
    do {
      const { node } = cur;
      if (node.type.id === Identifier) {
        // Make sure prevSibling is using the proper scope
        if (
          node.prevSibling?.type.id !== Parent &&
          node.prevSibling?.type.id !== Resource &&
          node.prevSibling?.type.id !== Span
        ) {
          const from = node.prevSibling ? node.prevSibling.from : node.from - 1;
          const to = node.prevSibling ? node.prevSibling.to : node.from - 1;
          const message = 'Add resource or span scope to attribute to improve query performance.';
          markers.push(getMarker(severity, message, model, from, to));
        }
      }
    } while (cur.next());
  }

  return markers;
};

export const getMarker = (
  severity: number,
  message: string,
  model: monacoTypes.editor.ITextModel,
  from: number,
  to: number
) => {
  let startLine = 0;
  let endLine = 0;
  let start = from;
  let end = to;

  while (start > 0) {
    startLine++;
    start -= model.getLineLength(startLine) + 1; // new lines don't count for getLineLength() but they still count as a character for the parser
  }
  while (end > 0) {
    endLine++;
    end -= model.getLineLength(endLine) + 1;
  }

  return {
    message,
    severity,

    startLineNumber: startLine,
    endLineNumber: endLine,

    // `+ 2` because of the above computations
    startColumn: start + model.getLineLength(startLine) + 2,
    endColumn: end + model.getLineLength(endLine) + 2,
  };
};
