package dirtoexcel

import (
	"fmt"
	"math"
	"os"
	"regexp"
	"sort"
	"strconv"
	"strings"
	"time"

	"github.com/lmittmann/tint"
	"github.com/spf13/cobra"
	"github.com/xuri/excelize/v2"
	"golang.org/x/exp/slog"
)

func init() {
	slog.SetDefault(slog.New(tint.Options{
		Level:      slog.LevelDebug,
		TimeFormat: time.Kitchen,
	}.NewHandler(os.Stderr)))
}

const re = `^(?P<company>[a-zA-Z0-9-\s]+)(?:_[a-zA-Z0-9]+)?_(?P<value>\d+\.\d{1,2})`

type Value struct {
	Company string
	Value   float64
}

type Values []Value

type Categories map[string]Values

func (c Categories) Insert(company, value string) error {
	fValue, err := strconv.ParseFloat(value, 32)
	if err != nil {
		return fmt.Errorf("failed to convert string to float: %w", err)
	}

	fValue = math.Round(fValue*100) / 100

	company = strings.ToUpper(company)

	switch company {
	case "ALDI", "EDEKA":
		c["Food"] = append(c["Food"], Value{Company: company, Value: fValue})
	case "AMAZON":
		c["NonFood"] = append(c["NonFood"], Value{Company: company, Value: fValue})
	default:
		c["Other"] = append(c["Other"], Value{Company: company, Value: fValue})
	}

	return nil
}

func Run(cmd *cobra.Command, args []string) {
	outfile, err := cmd.Flags().GetString("out")
	if err != nil {
		slog.Error("failed to get outfile string", "error", err)
		os.Exit(1)
	}

	if outfile == "" {
		outfile = fmt.Sprintf("%d.xlsx", time.Now().Unix())
	}

	if err := Create(outfile, args[0]); err != nil {
		slog.Error("failed to create excel", "error", err)
		os.Exit(1)
	}
}

func Create(out, dir string) error {
	log := slog.With("dir", dir, "out", out)

	c := Categories{}

	f := excelize.NewFile()
	defer func() {
		if err := f.Close(); err != nil {
			log.Error("failed to close excel file")
		}
	}()

	files, err := os.ReadDir(dir)
	if err != nil {
		return fmt.Errorf("failed to read dir: %w", err)
	}

	r, err := regexp.Compile(re)
	if err != nil {
		return fmt.Errorf("failed to compile regex: %w", err)
	}

	// Extract data from filenames. Filling them into categories.
	for _, i := range files {
		if i.IsDir() {
			continue
		}

		log.Info("found", "file", i.Name())

		res := r.FindAllStringSubmatch(i.Name(), -1)
		if res == nil {
			log.Error("couldnt find match", "file", i.Name())

			return fmt.Errorf("nothing found")
		}

		if len(res) != 1 || len(res[0]) != 3 {
			return fmt.Errorf("strange numbers of matches")
		}

		company := res[0][1]
		value := res[0][2]

		log.Debug("extracted", slog.String("company", company), slog.String("value", value))

		if err := c.Insert(company, value); err != nil {
			return fmt.Errorf("failed to insert data: %w", err)
		}
	}

	if _, err := f.NewSheet("Overview"); err != nil {
		return fmt.Errorf("failed to add overview sheet: %w", err)
	}

	catLength := 0

	for cat, item := range c {

		if _, err := f.NewSheet(cat); err != nil {
			return fmt.Errorf("failed to create new sheet: %w", err)
		}

		item = CalcAndSort(item)

		valueLength := 0

		for _, i := range item {
			if err := f.SetCellStr(cat, fmt.Sprintf("A%d", valueLength+1), i.Company); err != nil {
				return fmt.Errorf("failed to set cell: %w", err)
			}

			if err := f.SetCellFloat(cat, fmt.Sprintf("B%d", valueLength+1), i.Value, 2, 64); err != nil {
				return fmt.Errorf("failed to set cell: %w", err)
			}

			valueLength += 1
		}

		if err := createCategoryChart(cat, valueLength, f); err != nil {
			return fmt.Errorf("failed to create category chart: %w", err)
		}

		// Add to overview.
		if err := f.SetCellStr("Overview", fmt.Sprintf("A%d", catLength+1), cat); err != nil {
			return fmt.Errorf("failed to set category to overview: %w", err)
		}

		if err := f.SetCellFormula("Overview", fmt.Sprintf("B%d", catLength+1), fmt.Sprintf("=SUM(%s!B1:B%d)", cat, valueLength)); err != nil {
			return fmt.Errorf("failed to set sum to overview: %w", err)
		}

		if err := createCategoryChart("Overview", catLength+1, f); err != nil {
			return fmt.Errorf("failed to create overview chat: %w", err)
		}

		catLength += 1

	}

	if err := f.DeleteSheet("Sheet1"); err != nil {
		return fmt.Errorf("failed to remove default sheet: %w", err)
	}

	if err := f.SaveAs(out); err != nil {
		return fmt.Errorf("failed to save excel: %w", err)
	}

	log.Info("created excel")

	return nil
}

func createCategoryChart(category string, length int, f *excelize.File) error {
	if err := f.AddChart(category, "C1", &excelize.Chart{
		Type: excelize.Doughnut,
		Series: []excelize.ChartSeries{
			{
				Name:       "Amount",
				Categories: fmt.Sprintf("%s!A1:A%d", category, length),
				Values:     fmt.Sprintf("%s!B1:B%d", category, length),
			},
		},
		Format: excelize.GraphicOptions{
			OffsetX: 15,
			OffsetY: 10,
		},
		Legend: excelize.ChartLegend{
			Position: "right",
		},
		Title: excelize.ChartTitle{
			Name: category,
		},
		PlotArea: excelize.ChartPlotArea{
			ShowCatName:     false,
			ShowLeaderLines: false,
			ShowPercent:     true,
			ShowSerName:     false,
			ShowVal:         false,
		},
		ShowBlanksAs: "zero",
	}); err != nil {
		return fmt.Errorf("failed to create chart: %w", err)
	}

	return nil
}

func CalcAndSort(v Values) Values {
	n := Values{}

	for _, i := range v {
		added := false

		for k, v := range n {
			if i.Company == v.Company {
				n[k].Value += i.Value

				added = true

				break
			}
		}

		if !added {
			n = append(n, i)
		}
	}

	// Sorting for company names.
	sort.SliceStable(n, func(i, j int) bool {
		return n[i].Company < n[j].Company
	})

	return n
}