pkg/sdk/flags/strvals/parser.go

// Licensed to Elasticsearch B.V. under one or more contributor
// license agreements. See the NOTICE file distributed with
// this work for additional information regarding copyright
// ownership. Elasticsearch B.V. licenses this file to you 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 strvals

import (
	"bytes"
	"errors"
	"fmt"
	"io"
	"strconv"
	"strings"

	"sigs.k8s.io/yaml"
)

// ErrNotList indicates that a non-list was treated as a list.
var ErrNotList = errors.New("not a list")

// ToYAML takes a string of arguments and converts to a YAML document.
func ToYAML(s string) (string, error) {
	m, err := Parse(s)
	if err != nil {
		return "", fmt.Errorf("unable to parse input as YAML: %w", err)
	}
	d, err := yaml.Marshal(m)
	if err != nil {
		return "", fmt.Errorf("unable to marshal content as YAML: %w", err)
	}

	return strings.TrimSuffix(string(d), "\n"), nil
}

// Parse parses a set line.
//
// A set line is of the form name1=value1,name2=value2
func Parse(s string) (map[string]interface{}, error) {
	vals := map[string]interface{}{}
	scanner := bytes.NewBufferString(s)
	t := newParser(scanner, vals, false)
	err := t.parse()
	return vals, err
}

// ParseString parses a set line and forces a string value.
//
// A set line is of the form name1=value1,name2=value2
func ParseString(s string) (map[string]interface{}, error) {
	vals := map[string]interface{}{}
	scanner := bytes.NewBufferString(s)
	t := newParser(scanner, vals, true)
	err := t.parse()
	return vals, err
}

// ParseInto parses a strvals line and merges the result into dest.
//
// If the strval string has a key that exists in dest, it overwrites the
// dest version.
func ParseInto(s string, dest map[string]interface{}) error {
	scanner := bytes.NewBufferString(s)
	t := newParser(scanner, dest, false)
	return t.parse()
}

// ParseFile parses a set line, but its final value is loaded from the file at the path specified by the original value.
//
// A set line is of the form name1=path1,name2=path2
//
// When the files at path1 and path2 contained "val1" and "val2" respectively, the set line is consumed as
// name1=val1,name2=val2
func ParseFile(s string, reader RunesValueReader) (map[string]interface{}, error) {
	vals := map[string]interface{}{}
	scanner := bytes.NewBufferString(s)
	t := newFileParser(scanner, vals, reader)
	err := t.parse()
	return vals, err
}

// ParseIntoString parses a strvals line and merges the result into dest.
//
// This method always returns a string as the value.
func ParseIntoString(s string, dest map[string]interface{}) error {
	scanner := bytes.NewBufferString(s)
	t := newParser(scanner, dest, true)
	return t.parse()
}

// ParseIntoFile parses a filevals line and merges the result into dest.
//
// This method always returns a string as the value.
func ParseIntoFile(s string, dest map[string]interface{}, reader RunesValueReader) error {
	scanner := bytes.NewBufferString(s)
	t := newFileParser(scanner, dest, reader)
	return t.parse()
}

// RunesValueReader is a function that takes the given value (a slice of runes)
// and returns the parsed value
type RunesValueReader func([]rune) (interface{}, error)

// parser is a simple parser that takes a strvals line and parses it into a
// map representation.
//
// where sc is the source of the original data being parsed
// where data is the final parsed data from the parses with correct types
type parser struct {
	sc     *bytes.Buffer
	data   map[string]interface{}
	reader RunesValueReader
}

func newParser(sc *bytes.Buffer, data map[string]interface{}, stringBool bool) *parser {
	stringConverter := func(rs []rune) (interface{}, error) {
		return typedVal(rs, stringBool), nil
	}
	return &parser{sc: sc, data: data, reader: stringConverter}
}

func newFileParser(sc *bytes.Buffer, data map[string]interface{}, reader RunesValueReader) *parser {
	return &parser{sc: sc, data: data, reader: reader}
}

func (t *parser) parse() error {
	for {
		err := t.key(t.data)
		if err == nil {
			continue
		}
		if errors.Is(err, io.EOF) {
			return nil
		}
		return err
	}
}

func runeSet(r []rune) map[rune]bool {
	s := make(map[rune]bool, len(r))
	for _, rr := range r {
		s[rr] = true
	}
	return s
}

//nolint:gocyclo,errorlint // imported code
func (t *parser) key(data map[string]interface{}) error {
	stop := runeSet([]rune{'=', '[', ',', '.'})
	for {
		switch k, last, err := runesUntil(t.sc, stop); {
		case err != nil:
			if len(k) == 0 {
				return err
			}
			return fmt.Errorf("key %q has no value", string(k))
		case last == '[':
			// We are in a list index context, so we need to set an index.
			i, err := t.keyIndex()
			if err != nil {
				return fmt.Errorf("error parsing index: %w", err)
			}
			kk := string(k)
			// Find or create target list
			list := []interface{}{}
			if _, ok := data[kk]; ok {
				list = data[kk].([]interface{})
			}

			// Now we need to get the value after the ].
			list, err = t.listItem(list, i)
			set(data, kk, list)
			return err
		case last == '=':
			vl, e := t.valList()
			switch e {
			case nil:
				set(data, string(k), vl)
				return nil
			case io.EOF:
				set(data, string(k), "")
				return e
			case ErrNotList:
				rs, e := t.val()
				if e != nil && e != io.EOF {
					return e
				}
				v, e := t.reader(rs)
				set(data, string(k), v)
				return e
			default:
				return e
			}

		case last == ',':
			// No value given. Set the value to empty string. Return error.
			set(data, string(k), "")
			return fmt.Errorf("key %q has no value (cannot end with ,)", string(k))
		case last == '.':
			// First, create or find the target map.
			inner := map[string]interface{}{}
			if _, ok := data[string(k)]; ok {
				inner = data[string(k)].(map[string]interface{})
			}

			// Recurse
			e := t.key(inner)
			if len(inner) == 0 {
				return fmt.Errorf("key map %q has no value", string(k))
			}
			set(data, string(k), inner)
			return e
		}
	}
}

func set(data map[string]interface{}, key string, val interface{}) {
	// If key is empty, don't set it.
	if key == "" {
		return
	}
	data[key] = val
}

func setIndex(list []interface{}, index int, val interface{}) []interface{} {
	if len(list) <= index {
		newlist := make([]interface{}, index+1)
		copy(newlist, list)
		list = newlist
	}
	list[index] = val
	return list
}

func (t *parser) keyIndex() (int, error) {
	// First, get the key.
	stop := runeSet([]rune{']'})
	v, _, err := runesUntil(t.sc, stop)
	if err != nil {
		return 0, err
	}
	// v should be the index
	return strconv.Atoi(string(v))
}

//nolint:errorlint // imported code
func (t *parser) listItem(list []interface{}, i int) ([]interface{}, error) {
	stop := runeSet([]rune{'[', '.', '='})
	switch k, last, err := runesUntil(t.sc, stop); {
	case len(k) > 0:
		return list, fmt.Errorf("unexpected data at end of array index: %q", k)
	case err != nil:
		return list, err
	case last == '=':
		vl, e := t.valList()
		switch e {
		case nil:
			return setIndex(list, i, vl), nil
		case io.EOF:
			return setIndex(list, i, ""), err
		case ErrNotList:
			rs, e := t.val()
			if e != nil && e != io.EOF {
				return list, e
			}
			v, e := t.reader(rs)
			return setIndex(list, i, v), e
		default:
			return list, e
		}
	case last == '[':
		// now we have a nested list. Read the index and handle.
		i, err := t.keyIndex()
		if err != nil {
			return list, fmt.Errorf("error parsing index: %w", err)
		}
		// Now we need to get the value after the ].
		list2, err := t.listItem(list, i)
		return setIndex(list, i, list2), err
	case last == '.':
		// We have a nested object. Send to t.key
		inner := map[string]interface{}{}
		if len(list) > i {
			var ok bool
			inner, ok = list[i].(map[string]interface{})
			if !ok {
				// We have indices out of order. Initialize empty value.
				list[i] = map[string]interface{}{}
				inner = list[i].(map[string]interface{})
			}
		}

		// Recurse
		e := t.key(inner)
		return setIndex(list, i, inner), e
	default:
		return nil, fmt.Errorf("parse error: unexpected token %v", last)
	}
}

func (t *parser) val() ([]rune, error) {
	stop := runeSet([]rune{','})
	v, _, err := runesUntil(t.sc, stop)
	return v, err
}

//nolint:nolintlint // imported code
func (t *parser) valList() ([]interface{}, error) {
	r, _, e := t.sc.ReadRune()
	if e != nil {
		return []interface{}{}, e
	}

	if r != '{' {
		err := t.sc.UnreadRune()
		if err != nil {
			return []interface{}{}, err
		}
		return []interface{}{}, ErrNotList
	}

	list := []interface{}{}
	stop := runeSet([]rune{',', '}'})
	for {
		switch rs, last, err := runesUntil(t.sc, stop); {
		case err != nil:
			if errors.Is(err, io.EOF) {
				err = errors.New("list must terminate with '}'")
			}
			return list, err
		case last == '}':
			// If this is followed by ',', consume it.
			if r, _, e := t.sc.ReadRune(); e == nil && r != ',' {
				err := t.sc.UnreadRune()
				if err != nil {
					return []interface{}{}, err
				}
			}
			v, e := t.reader(rs)
			list = append(list, v)
			return list, e
		case last == ',':
			v, e := t.reader(rs)
			if e != nil {
				return list, e
			}
			list = append(list, v)
		}
	}
}

func runesUntil(in io.RuneReader, stop map[rune]bool) (runeset []rune, last rune, err error) {
	v := []rune{}
	for {
		switch r, _, e := in.ReadRune(); {
		case e != nil:
			return v, r, e
		case inMap(r, stop):
			return v, r, nil
		case r == '\\':
			next, _, e := in.ReadRune()
			if e != nil {
				return v, next, e
			}
			v = append(v, next)
		default:
			v = append(v, r)
		}
	}
}

func inMap(k rune, m map[rune]bool) bool {
	_, ok := m[k]
	return ok
}

func typedVal(v []rune, st bool) interface{} {
	val := string(v)

	if st {
		return val
	}

	if strings.EqualFold(val, "true") {
		return true
	}

	if strings.EqualFold(val, "false") {
		return false
	}

	if strings.EqualFold(val, "null") {
		return nil
	}

	if strings.EqualFold(val, "0") {
		return int64(0)
	}

	// If this value does not start with zero, try parsing it to an int
	if val != "" && val[0] != '0' {
		if iv, err := strconv.ParseInt(val, 10, 64); err == nil {
			return iv
		}
	}

	return val
}