import { LRLanguage, LanguageSupport, HighlightStyle, syntaxHighlighting, foldNodeProp, indentNodeProp } from '@codemirror/language';
import { styleTags, tags as t } from '@lezer/highlight';
import { parser } from './decodal-parser.js';

const parserWithMetadata = parser.configure({
  props: [
    styleTags({
      'Let In Match Import Default': t.keyword,
      'True False': t.bool,
      Identifier: t.variableName,
      String: t.string,
      Regex: t.regexp,
      'Integer Float': t.number,
      Comment: t.lineComment,
      'Plus Minus Star Slash PlusPlus Equal EqualEqual Bang BangEqual Amp AmpAmp PipePipe SlashSlash Gt Gte Lt Lte Arrow': t.operator,
      'LBrace RBrace': t.brace,
      'LBracket RBracket': t.squareBracket,
      'LParen RParen': t.paren,
      'Semicolon Comma Dot Colon': t.punctuation,
    }),
    indentNodeProp.add({
      Object: context => context.column(context.node.from) + context.unit,
      Array: context => context.column(context.node.from) + context.unit,
      MatchExpression: context => context.column(context.node.from) + context.unit,
      LetExpression: context => context.column(context.node.from) + context.unit,
    }),
    foldNodeProp.add({
      Object: foldDelimited('{', '}'),
      Array: foldDelimited('[', ']'),
      MatchExpression: foldDelimited('{', '}'),
    }),
  ],
});

function foldDelimited(open, close) {
  return (node, state) => {
    const text = state.doc.sliceString(node.from, node.to);
    const openIndex = text.indexOf(open);
    const closeIndex = text.lastIndexOf(close);
    if (openIndex < 0 || closeIndex <= openIndex) return null;
    const from = node.from + openIndex + open.length;
    const to = node.from + closeIndex;
    return from < to ? { from, to } : null;
  };
}

export const decodalLanguage = LRLanguage.define({
  parser: parserWithMetadata,
  languageData: {
    commentTokens: { line: '#' },
    closeBrackets: { brackets: ['(', '[', '{', '"'] },
  },
});

export const decodalHighlightStyle = HighlightStyle.define([
  { tag: t.keyword, color: '#93c5fd', fontWeight: '700' },
  { tag: t.variableName, color: 'inherit' },
  { tag: t.bool, color: '#fbbf24' },
  { tag: t.number, color: '#fbbf24' },
  { tag: t.string, color: '#86efac' },
  { tag: t.regexp, color: '#86efac' },
  { tag: t.lineComment, color: '#94a3b8', fontStyle: 'italic' },
  { tag: t.operator, color: '#f9a8d4' },
  { tag: [t.brace, t.squareBracket, t.paren, t.punctuation], color: '#f9a8d4' },
]);

export function decodal() {
  return new LanguageSupport(decodalLanguage, [syntaxHighlighting(decodalHighlightStyle)]);
}