diff --git a/src/sheet/sheet-templater.ts b/src/sheet/sheet-templater.ts
index 6aa9e15..ada10f8 100644
--- a/src/sheet/sheet-templater.ts
+++ b/src/sheet/sheet-templater.ts
@@ -18,7 +18,7 @@ export interface TemplatableCell {
   cloneWithTextContent(content: string): ThisType<this>;
 }
 
-type Indexable2DArray<T> = Record<number, Record<number, T>>;
+export type Indexable2DArray<T> = Record<number, Record<number, T>>;
 
 export function createTemplaterNoArgsFunction<R>(
   call: () => R,
diff --git a/src/xlsx.ts b/src/xlsx.ts
index bfe395e..4607ce6 100644
--- a/src/xlsx.ts
+++ b/src/xlsx.ts
@@ -7,13 +7,13 @@ import {
 } from "fast-xml-parser";
 import { startVisiting } from "./visitor-editor";
 import { Sheet } from "./sheet/sheet";
+import { SheetTemplater, TemplatableCell } from "./sheet/sheet-templater";
 
 const SHARED_STRINGS_ENTRY = "xl/sharedStrings.xml";
 
 export async function xlsxFillTemplate(
   xlsx: ReadableStream,
   output: WritableStream,
-  // @ts-expect-error will be used later
   input: any,
 ) {
   const zipWriter = new ZipWriter(output);
@@ -53,6 +53,7 @@ export async function xlsxFillTemplate(
 
     const result = await templater.template(
       await streamToText(contentStream.readable),
+      input,
     );
 
     await zipWriter.add(entry.filename, new BlobReader(new Blob([result])));
@@ -61,6 +62,52 @@ export async function xlsxFillTemplate(
   zipWriter.close();
 }
 
+class XlsxCell implements TemplatableCell {
+  cell: any;
+  text: string;
+
+  constructor(cell: any) {
+    // make sure it has the `v` inside of the cell
+    const cellV = cell["v"];
+
+    if (cellV === undefined)
+      throw new Error("Invalid cell, does not contain 'v'");
+
+    this.cell = cell;
+    this.text = String(cellV);
+
+    delete this.cell["v"];
+  }
+
+  buildCell(reference: `${string}${number}`): any {
+    this.cell["@_r"] = reference;
+    this.cell["v"] = this.text;
+
+    if (isNumeric(this.text)) {
+      this.cell["@_t"] = "n";
+    } else {
+      this.cell["@_t"] = "str";
+    }
+
+    return this.cell;
+  }
+
+  getTextContent(): string {
+    return this.text;
+  }
+
+  editTextContent(content: string): XlsxCell {
+    this.text = content;
+    return this;
+  }
+
+  cloneWithTextContent(content: string): XlsxCell {
+    const clone: XlsxCell = Object.assign({}, this);
+    clone.text = content;
+    return clone;
+  }
+}
+
 class XlsxTemplater {
   // a list of raw XML, make sure to pass it as-is. tends to be <t> tags
   private sharedStrings: any[] = [];
@@ -89,7 +136,7 @@ class XlsxTemplater {
     console.log(this.sharedStrings);
   }
 
-  async template(templateContent: string): Promise<string> {
+  async template(templateContent: string, data: any): Promise<string> {
     const options: X2jOptions & XmlBuilderOptions = {
       ignoreAttributes: false,
       parseTagValue: false,
@@ -110,17 +157,91 @@ class XlsxTemplater {
     // then we turn this sheet into a Sheet object so we can work with it easier
     const extractedData = await this.extract(sheetFilled);
 
-    console.log(extractedData);
-    console.log(extractedData.sheet.getSheet());
+    // pass the sheet into SheetTemplater for it to do the actual templating
+    const templater = new SheetTemplater(extractedData.sheet, {
+      rowInfo: extractedData.rowInfo,
+      colInfo: { ...extractedData.colInfo },
+    });
+
+    const templateResult = templater.interpret(data);
+    if (templateResult.status === "failed") {
+      throw new Error(templateResult.error.message);
+    }
+
+    const templatedSheet = templateResult.result;
+
+    // "inject" is a bit misleading, we're essentially injecting the cells that
+    // have been templated into the original sheet, without changing anything
+    // else other than the fields that do contain the cols, rows and cells.
+    const injectedSheet = this.inject(
+      templatedSheet.sheet,
+      sheetFilled,
+      templatedSheet.rowInfo ?? {},
+      templatedSheet.colInfo ?? {},
+    );
+
+    console.log("injected");
+    console.log(JSON.stringify(injectedSheet, null, 2));
 
     const builder = new XMLBuilder(options);
-    const result: string = builder.build(sheetFilled);
+    const result: string = builder.build(injectedSheet);
 
     return result;
   }
 
+  async inject(
+    sheetData: Sheet<XlsxCell>,
+    xlsxData: any,
+    rowInfo: Record<number, any>,
+    colInfo: Record<number, any>,
+  ): Promise<any> {
+    const rows: Record<number, { c: any[] | any } & any> = {};
+
+    const { rowBound, colBound } = sheetData.getBounds();
+    sheetData.optimizeSheet({ rowBound, colBound });
+
+    for (let r = 0; r <= rowBound; r++) {
+      const row: any[] = [];
+
+      for (let c = 0; c <= colBound; c++) {
+        const cell = sheetData.getCell(c, r);
+        if (cell === null) continue;
+
+        row.push(cell.buildCell(createAddressNumber(c, r)));
+      }
+
+      rows[r] = { ...rowInfo[r], c: row.length === 1 ? row[0] : row };
+    }
+
+    const visited = await startVisiting(xlsxData, {
+      before: {},
+      after: {
+        col: [
+          () => {
+            return {
+              newObj: Object.keys(colInfo)
+                .toSorted((a, b) => parseInt(a) - parseInt(b))
+                .map((i) => colInfo[parseInt(i)]),
+            };
+          },
+        ],
+        sheetData: [
+          () => {
+            return {
+              newObj: {
+                row: rows,
+              },
+            };
+          },
+        ],
+      },
+    });
+
+    return visited;
+  }
+
   async extract(parsedSheet: any): Promise<{
-    sheet: Sheet<any>;
+    sheet: Sheet<XlsxCell>;
     rowInfo: Record<number, any>;
     colInfo: (any & { min: number; max: number })[];
     mergeInfo: {
@@ -128,7 +249,7 @@ class XlsxTemplater {
       end: { col: number; row: number };
     }[];
   }> {
-    const sheet = new Sheet();
+    const sheet = new Sheet<XlsxCell>();
     const rowInfo: Record<number, any> = {};
     const colInfo: (any & { min: number; max: number })[] = [];
     const mergeInfo: {
@@ -202,7 +323,7 @@ class XlsxTemplater {
               const { col, row } = parseAddressNumber(cell["@_r"]);
               delete cell["@_r"];
 
-              sheet.setCell(col, row, cell);
+              sheet.setCell(col, row, new XlsxCell(cell));
             }
           },
         ],
@@ -279,6 +400,22 @@ function parseAddressNumber(address: string): { row: number; col: number } {
   return { row, col };
 }
 
+function createAddressNumber(col: number, row: number): `${string}${number}` {
+  if (col < 0 || row < 0) {
+    throw new Error("Column and row must be non-negative.");
+  }
+
+  const oneIndexedRow = row + 1;
+
+  let columnLetter = "";
+  while (col >= 0) {
+    columnLetter = String.fromCharCode(65 + (col % 26)) + columnLetter;
+    col = Math.floor(col / 26) - 1;
+  }
+
+  return `${columnLetter}${oneIndexedRow}`;
+}
+
 async function streamToText(
   stream: ReadableStream<Uint8Array>,
 ): Promise<string> {