import { parser } from '#parser/shrimp.ts'
import type { SyntaxNode } from '@lezer/common'
import { isIdentStart, isIdentChar } from './tokenizer'

// Turns a { curly string } into strings and nodes for interpolation
export const tokenizeCurlyString = (value: string): (string | [string, SyntaxNode])[] => {
  let pos = 1
  let start = 1
  let char = value[pos]
  const tokens: (string | [string, SyntaxNode])[] = []

  while (pos < value.length) {
    if (char === '$') {
      // escaped \$
      if (value[pos - 1] === '\\' && value[pos - 2] !== '\\') {
        tokens.push(value.slice(start, pos - 1))
        start = pos
        char = value[++pos]
        continue
      }

      tokens.push(value.slice(start, pos))
      start = pos

      if (value[pos + 1] === '(') {
        pos++ // slip opening '('

        char = value[++pos]
        if (!char) break

        let depth = 0
        while (char) {
          if (char === '(') depth++
          if (char === ')') depth--
          if (depth < 0) break
          char = value[++pos]
        }

        const input = value.slice(start + 2, pos) // skip '$('
        tokens.push([input, parser.parse(input).topNode])
        start = ++pos // skip ')'
      } else {
        char = value[++pos]
        if (!char) break
        if (!isIdentStart(char.charCodeAt(0))) break

        while (char && isIdentChar(char.charCodeAt(0)))
          char = value[++pos]

        const input = value.slice(start + 1, pos) // skip '$'
        tokens.push([input, parser.parse(input).topNode])
        start = pos-- // backtrack and start over
      }
    }

    char = value[++pos]
  }

  tokens.push(value.slice(start, pos - 1))

  return tokens
}