package csvparser

import (
	"strings"
	"errors"
)

type EncloserId int

const (
	None EncloserId = iota
	DoubleQuotes
	SingleQuotes
	RoundBrackets
	SquareBrackets
	CurlyBrackets
)

type Encloser struct {
	Open  byte
	Close byte
}

var EnclosersRunes = map[EncloserId]Encloser{
	DoubleQuotes:   Encloser{'"', '"'},
	SingleQuotes:   Encloser{'\'', '\''},
	RoundBrackets:  Encloser{'(', ')'},
	SquareBrackets: Encloser{'[', ']'},
	CurlyBrackets:  Encloser{'{', '}'},
}

type CsvParser struct {
	Enclosers       []EncloserId
	Delimiter       string
	Fields		[]string
	Line		string
}

func (parser *CsvParser) Init() {
	parser.Enclosers = []EncloserId{DoubleQuotes, SquareBrackets}
	parser.Delimiter = " \t"
}

func (parser *CsvParser) ExtractEnclosedFieldValue(line string, endChar byte) (string, error) {
	lineLen := len(line)
	for i := 1; i < lineLen; i++ {
		if line[i] == endChar && line[i-1] != '\\' {
			parser.Fields = append(parser.Fields, line[1:i])
			return line[i+1:], nil
		}
	}
	return line, errors.New("Encloser close not found")
}

func (parser *CsvParser) Parse(line string) error {
	var err error = nil
	for len(line) > 0 {
		line = strings.TrimLeft(line, parser.Delimiter)
		line = strings.TrimRight(line, parser.Delimiter)

		if len(line) == 0 {
			break
		}
		// Search for an encloser
		encloserId := None
		for _, id := range parser.Enclosers {
			if line[0] == EnclosersRunes[id].Open {
				encloserId = id
				break
			}
		}
		if encloserId != None {
			line, err = parser.ExtractEnclosedFieldValue(line, EnclosersRunes[encloserId].Close)
			if err != nil {
				return err
			}
		} else {
			nextSpace := strings.IndexAny(line, parser.Delimiter)
			if nextSpace != -1 {
				parser.Fields = append(parser.Fields, line[:nextSpace])
				line = line[nextSpace:]
			} else {
				parser.Fields = append(parser.Fields, line)
				line = ""
				break
			}

		}
	}
	return nil
}