package export

import (
	"bufio"
	"encoding/csv"
	"errors"
	"fmt"
	"io"
	"os"
	"reflect"
)

type CSV struct {
	fc     *os.File
	csv    *csv.Writer
	f      *File
	isNew  bool
	titles []string
}

func NewCSV(fileName string, limit int, param map[string]string) *CSV {
	return &CSV{
		f: NewFile(fileName, limit, param),
	}
}

func (e *CSV) slice() {
	if e.f.slice() {
		e.reset()
	}
}

func (e *CSV) SetParam(param map[string]string) {
	e.f.param = param
}

func (e *CSV) reset() {
	e.save()
	e.f.NextFile()
	e.Open()
	e.WriteTitle(nil)
	e.slice()
}

func (e *CSV) Open() error {
	var err error
	if e.f.IsFileExist() {
		e.fc, err = os.OpenFile(e.f.FileName(), os.O_APPEND|os.O_WRONLY, 0644)
		if err != nil {
			return err
		}
		e.f.SetRow(e.getLineCount(e.fc))
	} else {
		e.isNew = true
		e.fc, err = os.Create(e.f.FileName())
	}

	if err == nil {
		e.csv = csv.NewWriter(e.fc)
	}

	return nil
}

func (e *CSV) getLineCount(file io.Reader) (line int) {
	reader := bufio.NewReader(file)
	line = 0
	for {
		_, isPrefix, err := reader.ReadLine()
		if err != nil {
			break
		}
		if !isPrefix {
			line++
		}
	}
	return line
}

func (e *CSV) save() error {
	e.csv.Flush()
	e.fc.Close()
	return nil
}

func (e *CSV) WriteTitle(titles []string) error {

	if titles != nil {
		e.titles = titles
	}

	if e.titles != nil && e.isNew {
		e.Write(e.titles)
		e.isNew = false
	}
	return nil
}

func (e *CSV) Write(data interface{}) error {
	if e.f.slice() {
		e.reset()
	}

	v := reflect.ValueOf(data)
	if v.Kind() == reflect.Ptr {
		v = v.Elem()
	}
	if v.Kind() != reflect.Slice {
		return errors.New("数据无效，不是切片类型")
	}

	switch val := data.(type) {
	case []string:
		return e.csv.Write(val)
	case []interface{}:
		strs := make([]string, len(val))
		for i, v := range val {
			strs[i] = fmt.Sprintf("%v", v)
		}
		return e.csv.Write(strs)
	}
	return nil
}

func (e *CSV) Close() error {
	return e.save()
}