package parser

import (
	"strings"

	"asciigoat.org/core/lexer"
)

// AcceptQuotedString consumes a quoted string from the source
// and returns it unquoted and unescaped
func (p *TextParser) AcceptQuotedString() (string, bool, error) {
	r, _, err := p.ReadRune()
	switch {
	case err != nil:
		// nothing here
		return "", false, err
	case r != RuneQuotes:
		// not for us
		p.UnreadRune()
		return "", false, nil
	default:
		// let's roll
		s, err := lexQuotedString(p)
		switch {
		case err != nil:
			// bad quoted string
			return "", false, err
		default:
			// success
			return s, true, nil
		}
	}
}

func lexQuotedString(p *TextParser) (string, *lexer.Error) {
	for {
		r, _, err := p.ReadRune()
		switch {
		case err != nil:
			// incomplete
			return "", NewErrIncompleteQuotedString(p)
		case r == RuneQuotes:
			// end, remove quotes and process escaped characters
			return lexReturnUnescapedQuotedString(p)
		case r == RuneEscape:
			// escaped, take another
			_, _, err := p.ReadRune()
			if err != nil {
				// incomplete
				return "", NewErrIncompleteQuotedString(p)
			}
		case IsNewLine(r):
			// new lines within quoted values are acceptable
			p.UnreadRune()
			p.AcceptNewLine()
		default:
			// continue
		}
	}
}

func lexReturnUnescapedQuotedString(p *TextParser) (string, *lexer.Error) {
	// remove quotes
	s := p.String()
	l := len(s)
	s = s[1 : l-1]

	if strings.ContainsRune(s, RuneEscape) {
		// TODO: implement unescaping
		err := NewError(p.Position(), s, "escaped characters", lexer.ErrNotImplemented)
		return "", err
	}

	return s, nil
}

// Unquoted removes quotes the content and unescapes the content
func Unquoted(s string) (string, error) {
	var p TextParser
	if s == "" {
		return "", nil
	}

	p.InitString(s)
	unquoted, ok, err := p.AcceptQuotedString()
	switch {
	case err != nil:
		// bad string
		return "", err
	case ok:
		// success
		return unquoted, nil
	default:
		// not quoted
		return s, nil
	}
}