export function normalizeQuery (query) {
  // given a string such as 'this is "my query" go', returns
  // an array of tokens like this: ['this', 'is', 'my query', 'go']
  if (!query) {
    return []
  }
  return query.match(/\\?.|^$/g).reduce((p, c) => {
    if (c === '"') {
      p.quote ^= 1
    } else if (!p.quote && c === ' ') {
      p.a.push('')
    } else {
      p.a[p.a.length - 1] += c.replace(/\\(.)/, '$1')
    }
    return p
  }, { a: [''] }).a
}

export function parseTokens (tokens) {
  // given an array of tokens as returned by normalizeQuery,
  // returns a list of objects such as [
  //  {
  //    field: 'status',
  //    value: 'pending'
  //  },
  //  {
  //    field: null,
  //    value: 'hello'
  //  }
  // ]
  return tokens.map(t => {
    // we split the token on ":"
    const parts = t.split(/:(.+)/)
    if (parts.length === 1) {
      // no field specified
      return { field: null, value: t }
    }
    // first item is the field, second is the value, possibly quoted
    const field = parts[0]
    let rawValue = parts[1]

    // we remove surrounding quotes if any
    if (rawValue[0] === '"') {
      rawValue = rawValue.substring(1)
    }
    if (rawValue.slice(-1) === '"') {
      rawValue = rawValue.substring(0, rawValue.length - 1)
    }
    return { field, value: rawValue }
  })
}

export function compileTokens (tokens) {
  // given a list of tokens as returned by parseTokens,
  // returns a string query
  const parts = tokens.map(t => {
    let v = t.value
    const k = t.field
    if (v.indexOf(' ') > -1) {
      v = `"${v}"`
    }
    if (k) {
      return `${k}:${v}`
    } else {
      return v
    }
  })
  return parts.join(' ')
}