package systemdconfig

import (
	"strings"
)

type Section struct {
	fields           map[string]*Field // fields in the section, mapping keys to fields
	orderedFieldKeys []string          // keys, ordered as they appear in the section
}

// Gets the field for a given key
func (section *Section) Field(targetKey string) *Field {
	return section.fields[targetKey]
}

// Lists the fields which have key:values
func (section *Section) ListFields() []string {
	fieldKeys := []string{}
	for _, key := range section.orderedFieldKeys {
		if !strings.HasPrefix(key, "!") {
			fieldKeys = append(fieldKeys, key)
		}
	}
	return fieldKeys
}

// Sets the field for a given key, adds it if it doesn't exist
func (section *Section) SetField(targetKey string, value string) error {
	if !valueIsValid(value) {
		return &SyntaxError{value, errValueSyntax}
	}
	if strings.HasSuffix(value, "\\") {
		return &UnsupportedError{value, errMultiLineValuesUnsupported}
	}
	key := strings.TrimSpace(targetKey)
	if _, ok := section.fields[targetKey]; !ok {
		if !keyIsValid(key) {
			return &SyntaxError{targetKey, errKeySyntax}
		}
		targetKey = generateKeyForField(key, 0) // idx is ignored
		section.orderedFieldKeys = append(section.orderedFieldKeys, targetKey)
	}
	section.fields[targetKey] = &Field{key, value, ""}
	return nil
}

// Removes the field for a given key, if it exists
func (section *Section) RemoveField(targetKey string) error {
	if !keyIsValid(targetKey) {
		return &SyntaxError{targetKey, errKeySyntax}
	}
	if _, ok := section.fields[targetKey]; ok {
		delete(section.fields, targetKey)
		updatedKeys := []string{}
		for _, key := range section.orderedFieldKeys {
			if key != targetKey {
				updatedKeys = append(updatedKeys, key)
			}
		}
		section.orderedFieldKeys = updatedKeys
	}
	return nil
}

// Returns if the section has a field for a given key
func (section *Section) HasField(targetKey string) bool {
	_, ok := section.fields[targetKey]
	return ok
}