package export

import (
	"fmt"
	"reflect"
	"strconv"
	"strings"

	"github.com/xuri/excelize/v2"
)

type Exporter struct {
	File             string
	Path             string
	Sheets           []string
	Titles           []Title
	Data             interface{}
	xlsx             *excelize.File
	GlobalTitleStyle *excelize.Style
	GlobalCellStyle  *excelize.Style
	preLocation      *CellLocation
}

func NewExporter() *Exporter {
	return &Exporter{
		xlsx: excelize.NewFile(),
	}
}

func DefaultExporter() *Exporter {
	return &Exporter{
		xlsx:             excelize.NewFile(),
		GlobalTitleStyle: DefaultTitleStyle(),
		GlobalCellStyle:  DefaultCellStyle(),
		Sheets:           []string{"Sheet1"},
	}
}

func (e *Exporter) newSheet() error {
	for _, sheet := range e.Sheets {
		_, err := e.xlsx.NewSheet(sheet)
		if err != nil {
			return fmt.Errorf("init sheet error:%s", err)
		}
	}
	return nil
}

func (e *Exporter) Export(sheetIndex int) error {
	if len(e.Sheets) == 0 {
		return fmt.Errorf("excel file has no sheet")
	}
	err := e.newSheet()
	if err != nil {
		return err
	}
	if len(e.Titles) == 0 {
		return fmt.Errorf("excel title is null")
	}
	sheet := e.Sheets[sheetIndex]
	e.SetTitle(sheet)
	v := reflect.ValueOf(e.Data)
	if v.Kind() != reflect.Pointer {
		return fmt.Errorf("data must be pointer")
	}
	switch v.Elem().Kind() {
	case reflect.Slice:
		for i := 0; i < v.Elem().Len(); i++ {
			value := v.Elem().Index(i)
			if value.Kind() != reflect.Struct {
				return fmt.Errorf("element must be struct")
			}
			e.dealElement(sheet, value)
		}
	case reflect.Struct:
		e.dealElement(sheet, v.Elem())
	default:
		return fmt.Errorf("data must be slice or struct")
	}
	return e.Save()
}

func (e *Exporter) dealElement(sheet string, data reflect.Value) {
	for i := 0; i < data.NumField(); i++ {
		field := data.Field(i)
		t := data.Type().Field(i)
		tag, ok := t.Tag.Lookup("export")
		switch field.Kind() {
		case reflect.Struct:
			// 如果是结构体类型，但是没有export标签，则进行递归，否则直接处理（例如time.Time类型是结构体，但是可能需要导出）
			if !ok {
				e.dealElement(sheet, field)
			} else {
				e.writeCell(sheet, field, tag)
			}
		// 该逻辑有待验证
		case reflect.Slice:
			for j := 0; j < field.Len(); j++ {
				value := field.Index(j)
				if value.Kind() == reflect.Struct {
					e.dealElement(sheet, value)
				}
			}
		default:
			if ok {
				e.writeCell(sheet, field, tag)
			}

		}
	}
}

func (e *Exporter) writeCell(sheet string, field reflect.Value, tag string) {
	tagMap := dealTag(tag)
	x, _ := strconv.Atoi(tagMap["x"])
	y, _ := strconv.Atoi(tagMap["y"])
	colSpan, _ := strconv.Atoi(tagMap["colspan"])
	rowSpan, _ := strconv.Atoi(tagMap["rowspan"])
	loop := tagMap["loop"]
	var location Location
	if e.preLocation != nil {
		if loop != "" {
			y = e.preLocation.BottomY
			if x <= e.preLocation.RightX {
				x = e.preLocation.RightX + 1
			}
		} else {
			if x > e.preLocation.RightX {
				y = e.preLocation.TopY
			} else if x <= e.preLocation.RightX {
				y = e.preLocation.BottomY + 1
			}
		}
	}
	location = Location{
		X: x,
		Y: y,
	}
	value := value(field)
	cell := Cell{
		Location: location,
		Rowspan:  rowSpan,
		Colspan:  colSpan,
		Value:    value,
	}
	e.SetCell(sheet, cell)
}

func value(field reflect.Value) (val string) {
	mthV := field.MethodByName("String")
	if !mthV.IsValid() && field.CanAddr() {
		mthV = field.Addr().MethodByName("String")
	}
	if mthV.IsValid() && mthV.Kind() == reflect.Func && mthV.Type().NumIn() == 0 {
		callV := mthV.Call(nil)

		if len(callV) > 0 {
			val = fmt.Sprintf("%s", callV[0].String())

			return
		}
	}
	if field.CanUint() {
		val = fmt.Sprintf("%d", field.Uint())

	} else if field.CanInt() {
		val = fmt.Sprintf("%d", field.Int())

	} else if field.CanFloat() {
		val = fmt.Sprintf("%f", field.Float())

	} else {
		val = fmt.Sprintf("%s", field.String())
	}
	return
}

func dealTag(tag string) map[string]string {
	tag_list := strings.Split(tag, ",")
	tag_map := make(map[string]string)
	for _, tag := range tag_list {
		tag_kv := strings.Split(tag, ":")
		if len(tag_kv) != 2 {
			continue
		}
		tag_map[tag_kv[0]] = tag_kv[1]
	}
	return tag_map
}

func (e *Exporter) Save() error {
	return e.xlsx.SaveAs(fmt.Sprintf("%s/%s", e.Path, e.File))
}