/*
Copyright 2018 The KubeSphere Authors.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package test

import (
	"bufio"
	"bytes"
	"io"

	k8syaml "k8s.io/apimachinery/pkg/util/yaml"
)

const maxExecutiveEmpties = 100

// Scanner scans a yaml manifest file for manifest tokens delimited by "---".
// See bufio.Scanner for semantics.
type Scanner struct {
	reader  *k8syaml.YAMLReader
	token   []byte // Last token returned by split.
	err     error  // Sticky error.
	empties int    // Count of successive empty tokens.
	done    bool   // Scan has finished.
}

func NewYAMLScanner(b []byte) *Scanner {
	r := bufio.NewReader(bytes.NewBuffer(b))
	return &Scanner{reader: k8syaml.NewYAMLReader(r)}
}

func (s *Scanner) Err() error {
	if s.err == io.EOF {
		return nil
	}
	return s.err
}

func (s *Scanner) Scan() bool {
	if s.done {
		return false
	}

	var (
		tok []byte
		err error
	)

	for {
		tok, err = s.reader.Read()
		if err != nil {
			if err == io.EOF {
				s.done = true
			}
			s.err = err
			return false
		}
		if len(bytes.TrimSpace(tok)) == 0 {
			s.empties++
			if s.empties > maxExecutiveEmpties {
				panic("yaml.Scan: too many empty tokens without progressing")
			}
			continue
		}
		s.empties = 0
		s.token = tok
		return true
	}
}

func (s *Scanner) Text() string {
	return string(s.token)
}

func (s *Scanner) Bytes() []byte {
	return s.token
}