// Package parser parses dosini-style files
package parser

import (
	"io"

	"asciigoat.org/core/lexer"
)

// Parser parses a dosini-style document
type Parser struct {
	src *lexer.Reader

	OnSection func(pos lexer.Position, name, subname string, hasSubname bool) error
	OnField   func(pos lexer.Position, key, value string) error
	OnComment func(pos lexer.Position, comment string) error
	OnError   func(pos lexer.Position, content string, err error) error
}

func defaultOnSection(_ lexer.Position, _, _ string, _ bool) error { return nil }
func defaultOnField(_ lexer.Position, _, _ string) error           { return nil }
func defaultOnComment(_ lexer.Position, _ string) error            { return nil }

func defaultOnError(pos lexer.Position, content string, err error) error {
	return &lexer.Error{
		Line:    pos.Line,
		Column:  pos.Column,
		Content: content,
		Err:     err,
	}
}

func (p *Parser) setDefaults() {
	if p.OnSection == nil {
		p.OnSection = defaultOnSection
	}

	if p.OnField == nil {
		p.OnField = defaultOnField
	}

	if p.OnComment == nil {
		p.OnComment = defaultOnComment
	}

	if p.OnError == nil {
		p.OnError = defaultOnError
	}
}

// Run parses the source
func (p *Parser) Run() error {
	p.setDefaults()

	return lexer.Run(p.initialState)
}

// NewParser creates a dosini-style parser using
// an [io.Reader] as source
func NewParser(r io.Reader) *Parser {
	if r == nil {
		return nil
	}

	return &Parser{
		src: lexer.NewReader(r),
	}
}