import { useDocument } from '@terrace/core'
import { createStringReader } from '@terrace/core/readers/js-string'

export async function parse(lines, schema) {
  const doc = useDocument(createStringReader(lines))

  function createScope(line, matchers) {
    return {
      block: [line, []],
      handlers: [],
      matchers: matchers
    }
  }

  const macros = schema.macros

  const scopes = [createScope('root', {
    title ({ addHandler }) {
      addHandler(scope => [scope[0].split(' ')[0], scope[0].split(' ').slice(1).join(' ')])
    },
    options ({ addMatcher }) {
      addMatcher({
        parameter1({ addHandler }) {
          addHandler(scope => [scope[0].split(' ')[0], +scope[0].split(' ').slice(1).join(' ')])
        }
      })
    }
  })]

  let ended = false
  while (!ended) {
    ended = await doc.next()
    if (ended) break;
    const level = doc.level() + 1

    // Trigger macros for closed scopes.
    for (let i = scopes.length - 1; i >= level; --i) {
      const scope = scopes[i]
      const parent = scopes[i - 1]

      // Remove empty arrays from scopes without children.
      if (scope.block[1] && !scope.block[1].length) scope.block.length = 1

      // Postprocess scope with relevant macros.
      scope.block = scope.handlers.reduce((block, handler) => {
        return handler(block)
      }, [...scope.block])

      // Add to parent block.
      parent.block[1].push(scope.block)
    }

    // Reset scope length to avoid dangling scopes.
    scopes.length = level

    // Define current scope
    const scope = scopes[level] = createScope(doc.line(), {})
    // Determine parent for this scope.
    const parent = scopes[level - 1]

    // Add a postprocess handler for this scope.
    // Ie. When we leave the scope, rewrite it using this handler.
    function addHandler(handler) {
      scope.handlers.push(handler)
    }

    // Add matchers for this scope's children.
    function addMatcher(definition) {
      scope.matchers = definition
    }

    // Run matching matchers for this scope.
    if (parent.matchers[doc.head()]) {
      parent.matchers[doc.head()]({ addHandler, addMatcher })
    }
  }

  return scopes[0].block
}