From 924140c87d166a1f54c455031501eb5ce83df74e Mon Sep 17 00:00:00 2001
From: Todd <todd@baliance.com>
Date: Thu, 7 Sep 2017 17:13:03 -0500
Subject: [PATCH] spreadsheet: add support for merged cells

---
 README.md                                |   1 +
 _examples/spreadsheet/merged/main.go     |  35 +++++++++++++++++
 _examples/spreadsheet/merged/merged.xlsx | Bin 0 -> 4175 bytes
 spreadsheet/cell.go                      |  25 ++++++++++++
 spreadsheet/mergedcell.go                |  48 +++++++++++++++++++++++
 spreadsheet/sheet.go                     |  43 ++++++++++++++++++++
 spreadsheet/sheet_test.go                |  31 +++++++++++++++
 7 files changed, 183 insertions(+)
 create mode 100644 _examples/spreadsheet/merged/main.go
 create mode 100644 _examples/spreadsheet/merged/merged.xlsx
 create mode 100644 spreadsheet/mergedcell.go

diff --git a/README.md b/README.md
index b8a1f5ee..770bed30 100644
--- a/README.md
+++ b/README.md
@@ -41,6 +41,7 @@ and .pptx).
 - [Bar Chart](https://github.com/baliance/gooxml/tree/master/_examples/spreadsheet/bar-chart) Bar Charts
 - [Mutiple Charts](https://github.com/baliance/gooxml/tree/master/_examples/spreadsheet/multiple-charts) Multiple charts on a single sheet
 - [Named Cell Ranges](https://github.com/baliance/gooxml/tree/master/_examples/spreadsheet/named-ranges) Naming cell ranges
+- [Merged Cells](https://github.com/baliance/gooxml/tree/master/_examples/spreadsheet/merged) Merge and unmerge cells.
 
 ## Raw Types ##
 
diff --git a/_examples/spreadsheet/merged/main.go b/_examples/spreadsheet/merged/main.go
new file mode 100644
index 00000000..ab3f3821
--- /dev/null
+++ b/_examples/spreadsheet/merged/main.go
@@ -0,0 +1,35 @@
+// Copyright 2017 Baliance. All rights reserved.
+package main
+
+import (
+	"fmt"
+	"log"
+
+	"baliance.com/gooxml/spreadsheet"
+
+	sml "baliance.com/gooxml/schema/schemas.openxmlformats.org/spreadsheetml"
+)
+
+func main() {
+	ss := spreadsheet.New()
+	sheet := ss.AddSheet()
+
+	sheet.Cell("A1").SetString("Hello World!")
+	sheet.Cell("B1").SetString("will not be visible") // as it's not the first cell within a merged range Excel warns you when you do this through the UI
+	sheet.AddMergedCells("A1", "C2")
+
+	centered := ss.StyleSheet.AddCellStyle()
+	centered.SetHorizontalAlignment(sml.ST_HorizontalAlignmentCenter)
+	centered.SetVerticalAlignment(sml.ST_VerticalAlignmentCenter)
+	sheet.Cell("A1").SetStyle(centered)
+
+	for _, m := range sheet.MergedCells() {
+		fmt.Println("merged region", m.Reference(), "has contents", m.Cell().GetString())
+	}
+
+	if err := ss.Validate(); err != nil {
+		log.Fatalf("error validating sheet: %s", err)
+	}
+
+	ss.SaveToFile("merged.xlsx")
+}
diff --git a/_examples/spreadsheet/merged/merged.xlsx b/_examples/spreadsheet/merged/merged.xlsx
new file mode 100644
index 0000000000000000000000000000000000000000..aeb4e7c0690732ca6b0e1bf0a485ad58fda95688
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diff --git a/spreadsheet/cell.go b/spreadsheet/cell.go
index ff010a02..0729731b 100644
--- a/spreadsheet/cell.go
+++ b/spreadsheet/cell.go
@@ -245,6 +245,31 @@ func (c Cell) SetStyleIndex(idx uint32) {
 	c.x.SAttr = gooxml.Uint32(idx)
 }
 
+// GetString returns the string in a cell if it's an inline or string table
+// string.  Otherwise it returns an empty string.
+func (c Cell) GetString() string {
+	switch c.x.TAttr {
+	case sml.ST_CellTypeInlineStr:
+		if c.x.Is == nil || c.x.Is.T == nil {
+			return ""
+		}
+	case sml.ST_CellTypeS:
+		if c.x.V == nil {
+			return ""
+		}
+		id, err := strconv.Atoi(*c.x.V)
+		if err != nil {
+			return ""
+		}
+		s, err := c.w.SharedStrings.GetString(id)
+		if err != nil {
+			return ""
+		}
+		return s
+	}
+	return ""
+}
+
 func (c Cell) GetValue() (string, error) {
 	switch c.x.TAttr {
 	case sml.ST_CellTypeInlineStr:
diff --git a/spreadsheet/mergedcell.go b/spreadsheet/mergedcell.go
new file mode 100644
index 00000000..d3089705
--- /dev/null
+++ b/spreadsheet/mergedcell.go
@@ -0,0 +1,48 @@
+// Copyright 2017 Baliance. All rights reserved.
+//
+// Use of this source code is governed by the terms of the Affero GNU General
+// Public License version 3.0 as published by the Free Software Foundation and
+// appearing in the file LICENSE included in the packaging of this file. A
+// commercial license can be purchased by contacting sales@baliance.com.
+
+package spreadsheet
+
+import (
+	"fmt"
+	"strings"
+
+	sml "baliance.com/gooxml/schema/schemas.openxmlformats.org/spreadsheetml"
+)
+
+type MergedCell struct {
+	wb *Workbook
+	ws *sml.Worksheet
+	x  *sml.CT_MergeCell
+}
+
+// X returns the inner wrapped XML type.
+func (s MergedCell) X() *sml.CT_MergeCell {
+	return s.x
+}
+
+// SetReference sets the regin of cells that the merged cell applies to.
+func (s MergedCell) SetReference(ref string) {
+	s.x.RefAttr = ref
+}
+
+// Reference returns the region of cells that are merged.
+func (s MergedCell) Reference() string {
+	return s.x.RefAttr
+}
+
+// Cell returns the actual cell behind the merged region
+func (s MergedCell) Cell() Cell {
+	ref := s.Reference()
+	if idx := strings.Index(s.Reference(), ":"); idx != -1 {
+		ref = ref[0:idx]
+		return Sheet{w: s.wb, x: s.ws}.Cell(ref)
+	}
+	fmt.Println("DIE")
+	// couldn't find it, log an error?
+	return Cell{}
+}
diff --git a/spreadsheet/sheet.go b/spreadsheet/sheet.go
index f68ed89a..73cfe5fa 100644
--- a/spreadsheet/sheet.go
+++ b/spreadsheet/sheet.go
@@ -257,3 +257,46 @@ func (s Sheet) SetAutoFilter(rangeRef string) {
 		}
 	}
 }
+
+// AddMergedCells merges cells within a sheet.
+func (s Sheet) AddMergedCells(fromRef, toRef string) MergedCell {
+	// TODO: we might need to actually create the merged cells if they don't
+	// exist, but it appears to work fine on both Excel and LibreOffice just
+	// creating the merged region
+
+	if s.x.MergeCells == nil {
+		s.x.MergeCells = sml.NewCT_MergeCells()
+	}
+
+	merge := sml.NewCT_MergeCell()
+	merge.RefAttr = fmt.Sprintf("%s:%s", fromRef, toRef)
+
+	s.x.MergeCells.MergeCell = append(s.x.MergeCells.MergeCell, merge)
+	s.x.MergeCells.CountAttr = gooxml.Uint32(uint32(len(s.x.MergeCells.MergeCell)))
+	return MergedCell{s.w, s.x, merge}
+}
+
+// MergedCells returns the merged cell regions within the sheet.
+func (s Sheet) MergedCells() []MergedCell {
+	if s.x.MergeCells == nil {
+		return nil
+	}
+	ret := []MergedCell{}
+	for _, c := range s.x.MergeCells.MergeCell {
+		ret = append(ret, MergedCell{s.w, s.x, c})
+	}
+	return ret
+}
+
+// RemoveMergedCell removes merging from a cell range within a sheet.  The cells
+// that made up the merged cell remain, but are no lon merged.
+func (s Sheet) RemoveMergedCell(mc MergedCell) {
+	for i, c := range s.x.MergeCells.MergeCell {
+		if c == mc.X() {
+			copy(s.x.MergeCells.MergeCell[i:], s.x.MergeCells.MergeCell[i+1:])
+			s.x.MergeCells.MergeCell[len(s.x.MergeCells.MergeCell)-1] = nil
+			s.x.MergeCells.MergeCell = s.x.MergeCells.MergeCell[:len(s.x.MergeCells.MergeCell)-1]
+		}
+	}
+
+}
diff --git a/spreadsheet/sheet_test.go b/spreadsheet/sheet_test.go
index 118204fb..0ef6b244 100644
--- a/spreadsheet/sheet_test.go
+++ b/spreadsheet/sheet_test.go
@@ -132,3 +132,34 @@ func TestSheetNameLength(t *testing.T) {
 		t.Errorf("expected validation error with sheet name too long")
 	}
 }
+
+func TestMergedCell(t *testing.T) {
+	wb := spreadsheet.New()
+	sheet := wb.AddSheet()
+
+	expContent := "testing 123"
+	sheet.Cell("A1").SetString(expContent)
+	sheet.Cell("B1").SetString("in range, but not visible")
+	if len(sheet.MergedCells()) != 0 {
+		t.Errorf("new sheet should have no merged cells")
+	}
+	sheet.AddMergedCells("A1", "C2")
+	if len(sheet.MergedCells()) != 1 {
+		t.Errorf("sheet should have a single merged cells")
+	}
+
+	mc := sheet.MergedCells()[0]
+	expRef := "A1:C2"
+	if mc.Reference() != expRef {
+		t.Errorf("expected merged cell reference %s, got %s", expRef, mc.Reference())
+	}
+
+	if mc.Cell().GetString() != expContent {
+		t.Errorf("expected merged cell content to be '%s', got '%s'", expContent, mc.Cell().GetString())
+	}
+
+	sheet.RemoveMergedCell(mc)
+	if len(sheet.MergedCells()) != 0 {
+		t.Errorf("after removal, sheet should have no merged cells")
+	}
+}