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

export async function parse(lines, schema) {
  const typeHandlers = {
    string (doc) {
      return doc.tail().slice(1)
    },
    number (doc) {
      return +doc.tail().slice(1)
    },
    object (doc, handlers, definition, level) {
      level = level != null ? level : doc.level() + 1
      definition = lookup(definition)

      const object = {}
      for (let [key, child] of Object.entries(definition.values)) {
        child = lookup(child)
        if (key === 'any') key = null
        addHandler(handlers, level, key, child, (key, value) => {
          if (child.collate === 'array') {
            if (!object[key]) object[key] = []
            object[key].push(value)
            return
          } else if (child.collate === 'collection') {
            if (!object[key]) object[key] = []
            object[key].push({ [key]: value })
            return
          } else {
            object[key] = value
          }
        })
      }

      if (definition.tail) {
        const tailKey = definition.tail
        const tailType = definition.values[tailKey]
        object[tailKey] = typeHandlers[tailType](doc, handlers)
      }

      if (definition.text) {
        const textKey = definition.text
        const textType = 'string'
        object[textKey] = ''
        addHandler(handlers, level, '', textType, (key, value) => {
          object[textKey] += object[textKey] ? `\n${doc.line()}` : doc.line()
        })
      }

      return object
    },
    array (doc, handlers, definition, level) {
      level = level != null ? level : doc.level() + 1
      definition = lookup(definition)

      const array = []
      for (let [key, child] of Object.entries(definition.values)) {
        child = lookup(child)
        addHandler(handlers, level, key, child, (key, value) => {
          array.push(value)
        })
      }

      // if (definition.tail) {
      //   const tailKey = definition.tail
      //   const tailType = definition.values[tailKey]
      //   object[tailKey] = typeHandlers[tailType](doc, handlers)
      // }

      // if (definition.text) {
      //   const textKey = definition.text
      //   const textType = definition.values[textKey]
      //   object[textKey] = ''
      //   addHandler(handlers, level, '', textType, (key, value) => {
      //     object[textKey] += object[textKey] ? `\n${doc.line()}` : doc.line()
      //   })
      // }

      return array
    },
    collection (doc, handlers, definition, level) {
      level = level != null ? level : doc.level() + 1
      definition = lookup(definition)

      const collection = []
      for (let [key, child] of Object.entries(definition.values)) {
        child = lookup(child)
        addHandler(handlers, level, key, child, (key, value) => {
          collection.push({ [key]: value })
        })
      }

      // if (definition.tail) {
      //   const tailKey = definition.tail
      //   const tailType = definition.values[tailKey]
      //   object[tailKey] = typeHandlers[tailType](doc, handlers)
      // }

      // if (definition.text) {
      //   const textKey = definition.text
      //   const textType = definition.values[textKey]
      //   object[textKey] = ''
      //   addHandler(handlers, level, '', textType, (key, value) => {
      //     object[textKey] += object[textKey] ? `\n${doc.line()}` : doc.line()
      //   })
      // }

      return collection
    },
  }

  function lookup (definition) {
    const type = typeof definition === 'string' ? definition : definition.type
    const resolvedDefinition = schema.types[type] || definition
    return typeof definition === 'string' ? resolvedDefinition : Object.assign({}, definition, resolvedDefinition)
  }

  function registerTypes(typeHandlers, types) {
    for (const [key, definition] of Object.entries(types)) {
      const existingType = typeof definition === 'string' ? definition : definition.type
      typeHandlers[key] = typeHandlers[existingType]
    }
  }

  function addHandler(handlers, level, key, definition, resolve) {
    const type = typeof definition === 'string' ? definition : definition.type
    if (!handlers[level]) handlers[level] = []
    handlers[level].push({
      key,
      resolve,
      definition,
      handler: typeHandlers[type]
    })
  }

  const doc = useDocument(createStringReader(lines))
  const handlers = []

  registerTypes(typeHandlers, schema.types)

  const root = typeHandlers.object(doc, handlers, schema.root, 0)

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

    const unmatchedHandler = handlers[level]?.find(h => h.key === '')
    let matched = false
    for (const { key, definition, resolve, handler } of handlers[level] || []) {
      if (key && doc.head() !== key) continue;
      if (!doc.line()) continue;
      resolve(doc.head(), handler(doc, handlers, definition))
      matched = true
      break
    }
    if (!matched && unmatchedHandler) {
      const { resolve, definition, handler } = unmatchedHandler
      resolve(doc.head(), handler(doc, handlers, definition))
    }
  }

  return root
}