package badtudexo

import (
	"fmt"
	"strings"
	"os"
	xl "git.gabbott.dev/george/excelize/v2"
	st "saggytrousers"
)

type SplitAlgorithm int 
const (
	IndivAlgorithm SplitAlgorithm = iota + 1
	GroupAlgorithm
)

const SaveDirectory string = "bt-split"

// rows [][]any must NOT include the header. 
func indivSplit(rows [][]any, header []string, index int, dir, fn string) {
	st.Log(false, "bt.indivSplit: index (%v), dir (%v), fn (%v).", index, dir, fn)
	var uniq []any
	saveDir := fmt.Sprintf("%s/%s", dir, SaveDirectory)
	st.Log(false, "bt.indivSplit: saveDir = %v\n", saveDir)
	os.Mkdir(saveDir, 0777)

	// First pass: get all the unique values. 
	for _, row := range rows {
		v := row[index]
		if !st.InSliceAny(uniq, v) {
			uniq = append(uniq, v)
		}
	}

	// Rest of the passes: for each unique value, grab them and chuck all 
	// entries matching it to a file, then save it. 
	count, total := 0, 0
	for _, v := range uniq {
		//if (n == 0) { /* change for _, ... to: for n, ... if using
		//	// Skip the first one, as it is the header.
		//	continue
		//}
		pos := 1 
		suffix := deriveSplitSuffix(v)
		filename  := st.CreateFilepath(dir, SaveDirectory, fn, suffix)
		sheetname := st.MakeValidSheetName(st.CreateFilename(fn, suffix))


		// Create the new file, and append the header to it. 
		file := xl.NewFile()
		file.SetSheetName("Sheet1", sheetname)
		st.AppendToFile(file, sheetname, header, pos)
		pos++ 

		// Now add each matching row to the file as well. 
		for _, row := range rows {
			sv := row[index]
			if sv == v {
				st.AppendToFile(file, sheetname, row, pos)
				pos++
			}
		}

		// Finally, save the file, close it, and we can do it all again 
		// for the next unique value.
		filename = fmt.Sprintf("%s.xlsx", filename) 
		if err := file.SaveAs(filename); err != nil {
			st.ErrLog(true, "Unable to save [%s]\n", filename)
		} else {
			st.Log(true, "Saved [%s]\n", filename)
			count++
		}
		total++
	}
	st.Log(true, "Saved %v of %v files successfully.\n", count, total)
}

func deriveSplitSuffix(str any) string {
	s:= fmt.Sprintf("%v", str)
	if strings.HasSuffix(s,  "UTC") {
		return s[0:10]
	}

	return s
}

// func groupSplit(rows [][]string, header []string, index int, dir, fn string) map[string]*xl.File {
// }
// 
// func groupSave(m map[string]*xl.File) { 
// }



// Takes rows, and splits on the given index. Then saves each of these splits 
// as a separate file at the specified location and with the specified name. 
// rows must NOT include the header.
func Split(rows [][]any, header []string, index int, 
                         dir, filename string, 
			 algo SplitAlgorithm) {

	switch algo {
	case IndivAlgorithm:
		st.Log(false, "badtudexo.Split: algorithm = IndivAlgorithm\n")
		indivSplit(rows, header, index, dir, filename)
	// case GroupAlgorithm:
	// 	// TODO: implement these again.
	// 	m := groupSplit(rows, header, index, dir, filename)
	// 	groupSave(m)
	default:
		st.ErrLog(true, "badtudexo.Split received an invalid algorithm.\n")
		os.Exit(-1)
	}
}