1 files changed, 114 insertions, 0 deletions
diff --git a/split.go b/split.go
new file mode 100644
index 0000000..bfcf474
--- /dev/null
+++ b/split.go
@@ -0,0 +1,114 @@
+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)
+	}
+}