package export

import (
	"errors"
	"fmt"
	"github.com/tealeg/xlsx/v3"
	"os"
)

const sheet_name = "sheet_1"

type Export struct {
	index  int
	count  int //总数
	row    int //当前执行的数据行
	limit  int //导出限制
	path   string
	isNew  bool
	titles []string
	file   *xlsx.File
	sheet  *xlsx.Sheet
}

func NewExport(path string, limit int) *Export {
	return &Export{
		path:  path,
		limit: limit,
	}
}

func (e *Export) Title(titles []string) error {
	if e.file == nil || e.sheet == nil {
		return errors.New("没有执行open方法")
	}

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

	if e.titles != nil && e.isNew {
		row := e.sheet.AddRow()
		row.WriteSlice(e.titles, -1)
	}
	return nil
}

func (e *Export) fileName() string {
	return fmt.Sprintf(e.path, e.index)
}

func (e *Export) slice() {
	e.row++
	if e.row > e.limit {
		e.row = 0
		e.reset()
	}

}

func (e *Export) reset() {
	e.save()
	e.index++
	e.Open()
	e.Title(nil)
	e.slice()
}

func (e Export) Index() int {
	return e.index
}

func (e *Export) Export(data Entity) error {
	if e.file == nil || e.sheet == nil {
		return errors.New("没有执行open方法")
	}

	e.count = e.count + data.Size()
	for _, order := range data.Data() {
		e.slice()
		row := e.sheet.AddRow()
		row.WriteStruct(order, -1)
	}
	return e.save()
}

func (e *Export) Open() error {
	path := e.fileName()
	exist, err := e.isFielExist(path)
	if err != nil {
		return err
	}

	if exist {
		e.isNew = false
		if e.file, err = xlsx.OpenFile(path); err != nil {
			return err
		}
	} else {
		e.isNew = true
		e.file = xlsx.NewFile()
	}

	var ok bool
	e.sheet, ok = e.file.Sheet[sheet_name]
	if !ok {
		e.sheet, err = e.file.AddSheet(sheet_name)
		if err != nil {
			return err
		}
	} else {
		//需要处理偏移数据
		e.row = e.sheet.MaxRow - 1
	}

	return nil
}

func (e *Export) isFielExist(file string) (bool, error) {
	_, err := os.Stat(file)
	if err == nil {
		return true, nil
	}

	if os.IsNotExist(err) {
		return false, nil
	}

	return false, err
}

func (e *Export) save() error {
	return e.file.Save(e.fileName())
}