package srv_contentexcel

import (
	"bytes"
	"fmt"
	"strconv"
	"strings"

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

const (
	colID               = "ID"
	colTitle            = "标题"
	colDesc             = "描述"
	colKeyworld         = "关键词"
	colRedLineRemark    = "备注(红线-建议下架)"
	sheetName           = "Sheet1"
	excelHeaders        = 4
	colRedLineRemarkIdx = 4
)

var headerAliases = map[string]int{
	"id": 0, colID: 0,
	"title": 1, colTitle: 1,
	"desc": 2, "description": 2, colDesc: 2,
	"keyworld": 3, "keywords": 3, "keyword": 3, colKeyworld: 3,
	colRedLineRemark: colRedLineRemarkIdx,
}

func buildWorkbook(rows []ContentRow) ([]byte, error) {
	f := excelize.NewFile()
	defer f.Close()

	if err := f.SetSheetRow(sheetName, "A1", &[]string{colID, colTitle, colDesc, colKeyworld}); err != nil {
		return nil, err
	}

	for i, row := range rows {
		cell, err := excelize.CoordinatesToCellName(1, i+2)
		if err != nil {
			return nil, err
		}
		if err := f.SetSheetRow(sheetName, cell, &[]any{
			row.ID,
			row.Title,
			row.Desc,
			strings.Join(row.Keyworld, ","),
		}); err != nil {
			return nil, err
		}
	}

	var buf bytes.Buffer
	if err := f.Write(&buf); err != nil {
		return nil, err
	}
	return buf.Bytes(), nil
}

func parseWorkbook(data []byte) ([]ContentRow, error) {
	f, err := excelize.OpenReader(bytes.NewReader(data))
	if err != nil {
		return nil, fmt.Errorf("打开 Excel 失败: %w", err)
	}
	defer f.Close()

	sheets := f.GetSheetList()
	if len(sheets) == 0 {
		return nil, fmt.Errorf("Excel 无工作表")
	}

	rows, err := f.GetRows(sheets[0])
	if err != nil {
		return nil, fmt.Errorf("读取 Excel 失败: %w", err)
	}
	if len(rows) <= 1 {
		return nil, fmt.Errorf("Excel 无数据行")
	}

	colIndex := mapHeaderColumns(rows[0])
	if len(colIndex) < excelHeaders {
		return nil, fmt.Errorf("Excel 表头需包含: ID、标题、描述、关键词")
	}

	result := make([]ContentRow, 0, len(rows)-1)
	for lineNo, row := range rows[1:] {
		contentRow, ok, err := parseDataRow(row, colIndex, lineNo+2)
		if err != nil {
			return nil, err
		}
		if !ok {
			continue
		}
		result = append(result, contentRow)
	}
	if len(result) == 0 {
		return nil, fmt.Errorf("Excel 无有效数据行")
	}
	return result, nil
}

func mapHeaderColumns(header []string) map[int]int {
	index := make(map[int]int, excelHeaders)
	for i, name := range header {
		key := strings.ToLower(strings.TrimSpace(name))
		if col, ok := headerAliases[key]; ok {
			index[col] = i
		}
	}
	return index
}

func parseDataRow(row []string, colIndex map[int]int, lineNo int) (ContentRow, bool, error) {
	if remarkIdx, ok := colIndex[colRedLineRemarkIdx]; ok {
		if cellValue(row, remarkIdx) != "" {
			return ContentRow{}, false, nil
		}
	}

	idStr := cellValue(row, colIndex[0])
	if idStr == "" {
		return ContentRow{}, false, nil
	}
	id, err := strconv.ParseInt(idStr, 10, 64)
	if err != nil || id <= 0 {
		return ContentRow{}, false, fmt.Errorf("第 %d 行 ID 无效: %q", lineNo, idStr)
	}

	return ContentRow{
		ID:       id,
		Title:    cellValue(row, colIndex[1]),
		Desc:     cellValue(row, colIndex[2]),
		Keyworld: parseKeywords(cellValue(row, colIndex[3])),
	}, true, nil
}

func cellValue(row []string, index int) string {
	if index < 0 || index >= len(row) {
		return ""
	}
	return strings.TrimSpace(row[index])
}

func parseKeywords(raw string) []string {
	raw = strings.TrimSpace(raw)
	if raw == "" {
		return nil
	}
	raw = strings.NewReplacer("，", ",", "；", ",", ";", ",").Replace(raw)
	parts := strings.Split(raw, ",")
	keywords := make([]string, 0, len(parts))
	for _, part := range parts {
		part = strings.TrimSpace(part)
		if part != "" {
			keywords = append(keywords, part)
		}
	}
	return keywords
}