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 Parser struct {
	Enclosers       []EncloserId
	Delimiter       string
	Fields		[]string
	Line		string
}

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

func (parser *Parser) ExtractEnclosedFieldValue(endChar byte) error {
	lineLen := len(parser.Line)
	for i := 1; i < lineLen; i++ {
		if parser.Line[i] == endChar && parser.Line[i-1] != '\\' {
			parser.Fields = append(parser.Fields, parser.Line[0:i])
      parser.Line = parser.Line[i+1:]
			return nil
		}
	}
	return errors.New("Encloser close not found")
}

/*
* Usage: 
* import "../csv-parser/"
* var parser csvparser.Parser
* parser.init()
* parser.Parse("a b c d")
*/
func (parser *Parser) Parse(CsvLine string) error {
	var err error = nil

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

		}
	}
	return nil
}