package csvparser

import (
	"fmt"
	"strings"
	"unicode/utf8"
)

type CsvParser struct {
	enclosers []string
	delimiter rune
	fields    []string
}

func (p *CsvParser) Initialize(delimiter string, enclosers []string, lineFormat string) error {
	if utf8.RuneCountInString(delimiter) != 1 {
		return fmt.Errorf("delimiter shoud be one character")
	}
	p.enclosers = make([]string, 0)
	for _, encloser := range enclosers {
		if utf8.RuneCountInString(encloser) != 2 {
			return fmt.Errorf("encolser should have to characters")
		}
	}
	p.enclosers = enclosers
	p.delimiter = []rune(delimiter)[0]
	for _, pair := range enclosers {
		if utf8.RuneCountInString(pair) != 2 {
			return fmt.Errorf("encoloser should contain two characters: %s", pair)
		}
	}
	// line format is in the form of: field1 field2 ignore ...
	// if field name is ignore, it is parsed but not retained
	p.fields = strings.Split(lineFormat, " ")

	return nil
}

func (p *CsvParser) Parse(line string) (map[string]string, error) {
	currentFieldIndex := 0
	valueStart := 0
	escape := false
  enclosed := false

	ret := make(map[string]string)
	indexMax := len(line) - 1
  maxFieldIndex := len(p.fields) - 1
  delimiter := p.delimiter
	for index, r := range line {
    if r == '\\' {
      // Check if EOL before continue
      escape=true
      continue
    }
    if escape {
      escape=false
      continue
    }
    if r == delimiter {
      if p.fields[currentFieldIndex] != "ignore" {
        ret[p.fields[currentFieldIndex]] = line[valueStart : index]
      }
      currentFieldIndex++
      if currentFieldIndex > maxFieldIndex {
        break
      }
      valueStart = index + 1
      if enclosed {
        enclosed=false
        delimiter = p.delimiter
        // Omit next delimiter
        escape=true
      }
      continue
    }
    if index >= indexMax {
      if p.fields[currentFieldIndex] != "ignore" {
			  ret[p.fields[currentFieldIndex]] = line[valueStart:]
      }
      continue
    }

    for _, encloser := range p.enclosers {
      runes := []rune(encloser)
      if r == runes[0] {
        // opening encloser
        enclosed = true
        delimiter = runes[1]
        valueStart++
        break
      }
    }
  }
	return ret, nil
}