import {parser, props} from "@nextjournal/lezer-clojure"
import {NodeProp, SyntaxNode, NodeType} from "@lezer/common"
import {styleTags, tags} from "@lezer/highlight"
import {indentNodeProp, foldNodeProp, foldInside, LRLanguage, LanguageSupport, TreeIndentContext} from "@codemirror/language"

/// A language provider based on the [Lezer Clojure](https://github.com/nextjournal/lezer-clojure), extended with
/// highlighting and indentation information.

const {coll} = props

// debug
// const nodeText = (state, node: SyntaxNode) => { return state.doc.sliceString(node.from, node.to) }

export const clojureLanguage = LRLanguage.define({
  parser: parser.configure({
    props: [styleTags({NS: tags.keyword,
                       DefLike: tags.keyword,
                       "Operator/Symbol": tags.keyword,
                       "VarName/Symbol": tags.definition(tags.variableName),
                       // Symbol: tags.keyword,
                       // "'": tags.keyword, // quote
                       Boolean: tags.atom,
                       "DocString/...": tags.emphasis,
                       "Discard!": tags.comment,
                       Number: tags.number,
                       StringContent: tags.string,
                       "\"\\\"\"": tags.string, // need to pass something, that returns " when being parsed as JSON
                       Keyword: tags.atom,
                       Nil: tags.null,
                       LineComment: tags.lineComment,
                       RegExp: tags.regexp}),

            indentNodeProp.add((nodeType: NodeType) => {
              return (context: TreeIndentContext) => {
                let {pos, unit, node, state, baseIndent, textAfter} = context
                if (nodeType.prop(coll)) {
                  // same behaviour as in clojure-mode: args after operator are always 2-units indented
                  let parentBase = context.column(node.firstChild.to) // column at the right of parent opening-(
                  if ("List" == nodeType.name && ["NS", "DefLike", "Operator"].includes(node.firstChild.nextSibling.type.name)) {
                    return parentBase + 1
                  } else {
                    return parentBase
                  }
                } else {
                  return 0
                }
              }
            }),

            foldNodeProp.add({["Vector Map List"]: foldInside})]}),

  languageData: {commentTokens: {line: ";;"}}})

export function clojure() {
  return new LanguageSupport(clojureLanguage)
}