diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..ed52319
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1 @@
+.timeclock/*
\ No newline at end of file
diff --git a/src/app/Invoice/InvoiceHandler.ts b/src/app/Invoice/InvoiceHandler.ts
new file mode 100644
index 0000000..99d2623
--- /dev/null
+++ b/src/app/Invoice/InvoiceHandler.ts
@@ -0,0 +1,5 @@
+import { IInvoiceHandler } from "../../domain/Invoice/IInvoiceHandler.ts";
+
+export class InvoiceHandler implements IInvoiceHandler {
+    
+}
\ No newline at end of file
diff --git a/src/app/Punch/PunchHandler.ts b/src/app/Punch/PunchHandler.ts
new file mode 100644
index 0000000..b4aa7c2
--- /dev/null
+++ b/src/app/Punch/PunchHandler.ts
@@ -0,0 +1,43 @@
+import { IPunchHandler } from "../../domain/Punch/IPunchHandler.ts";
+import { Punch } from "../../domain/Punch/Punch.ts";
+import { PunchType } from "../../domain/Punch/PunchType.ts";
+import { executeShellCommandAsync } from "../../infra/IO/Shell.ts";
+import * as FileManager from "../../infra/IO/Files.ts";
+import { Shift } from "../../domain/Shift/Shift.ts";
+import { ShiftHandler } from "../Shift/ShiftHandler.ts";
+
+export class PunchHandler implements IPunchHandler {
+    constructor() {
+    }
+
+    async createPunchAsync(punch: Punch): Promise<void> {
+        if (punch.type === PunchType.Sart) {
+            await this.createStartPunchAsync(punch);
+        } else {
+            await this.createEndPunchAsync(punch);
+        }
+        await this.commitPunchAsync(punch);
+    }
+
+    private async commitPunchAsync(punch: Punch) {
+        const msg = punch.type == PunchType.Sart ? "START" : "END";
+        (await executeShellCommandAsync("git", ["commit", "-m", `\"TIMECLOCK PUNCH ${msg} - ${punch.user}\"`])).verifyZeroReturnCode();
+    }
+    
+    private async createStartPunchAsync(punch: Punch) {
+        await FileManager.createDirectoryAsync(punch.punchDir);
+        await Deno.writeTextFile(punch.punchFilePath, Date.now().toString());
+        (await executeShellCommandAsync("git", ["add", punch.punchFilePath])).verifyZeroReturnCode();
+    }
+    
+    private async createEndPunchAsync(punch: Punch) {
+        const nowUtcMs = Date.now().toString();
+        const punchStartUtcMs = await Deno.readTextFile(punch.punchFilePath);
+        const shift: Shift = new Shift(punch.user, punchStartUtcMs, nowUtcMs);
+
+        await Deno.remove(punch.punchFilePath);
+        (await executeShellCommandAsync("git", ["add", punch.punchFilePath])).verifyZeroReturnCode();
+
+        await new ShiftHandler().createShiftAsync(shift);
+    }
+}
\ No newline at end of file
diff --git a/src/app/Shift/ShiftHandler.ts b/src/app/Shift/ShiftHandler.ts
new file mode 100644
index 0000000..06ad99b
--- /dev/null
+++ b/src/app/Shift/ShiftHandler.ts
@@ -0,0 +1,13 @@
+import { IShiftHandler } from "../../domain/Shift/IShiftHandler.ts";
+import { Shift } from "../../domain/Shift/Shift.ts";
+import * as FileManager from "../../infra/IO/Files.ts";
+import { executeShellCommandAsync } from "../../infra/IO/Shell.ts";
+
+export class ShiftHandler implements IShiftHandler {
+
+  public async createShiftAsync(shift: Shift): Promise<void> {
+    await FileManager.createDirectoryAsync(shift.shiftDir);
+    await Deno.writeTextFile(shift.shiftFilePath, shift.diffHours.toString());
+    (await executeShellCommandAsync("git", ["add", shift.shiftFilePath])).verifyZeroReturnCode();
+  }
+}
\ No newline at end of file
diff --git a/src/app/timeclock.ts b/src/app/timeclock.ts
new file mode 100644
index 0000000..b795836
--- /dev/null
+++ b/src/app/timeclock.ts
@@ -0,0 +1,24 @@
+import { Punch } from "../domain/Punch/Punch.ts";
+import { PunchType } from "../domain/Punch/PunchType.ts";
+import { executeShellCommandAsync } from "../infra/IO/Shell.ts";
+import { PunchHandler } from "./Punch/PunchHandler.ts";
+
+async function validateCleanWorkingTreeAsync() {
+    const statusOutput = (await executeShellCommandAsync("git", ["status"])).verifyZeroReturnCode();
+    if (!statusOutput.stdout.includes("nothing to commit, working tree clean")) {
+        throw "punches must occur on a clean working tree";
+    }
+}
+const _punchHandler = new PunchHandler();
+async function main() {
+    const user: string = Deno.args[0];
+    const isEndPunch: boolean = Deno.args.some(x => x === "--end");
+    const punchType: PunchType = isEndPunch ? PunchType.End : PunchType.Sart;
+
+    const punch = new Punch(punchType, user);
+    
+    await validateCleanWorkingTreeAsync();
+    await _punchHandler.createPunchAsync(punch);
+}
+
+await main();
diff --git a/src/domain/Constants.ts b/src/domain/Constants.ts
new file mode 100644
index 0000000..3551177
--- /dev/null
+++ b/src/domain/Constants.ts
@@ -0,0 +1 @@
+export const ONE_HOUR_IN_MS: number = 3600000;
\ No newline at end of file
diff --git a/src/domain/Invoice/IInvoiceHandler.ts b/src/domain/Invoice/IInvoiceHandler.ts
new file mode 100644
index 0000000..ce4f83c
--- /dev/null
+++ b/src/domain/Invoice/IInvoiceHandler.ts
@@ -0,0 +1,3 @@
+export interface IInvoiceHandler {
+    
+}
\ No newline at end of file
diff --git a/src/domain/Invoice/Invoice.ts b/src/domain/Invoice/Invoice.ts
new file mode 100644
index 0000000..ea8b604
--- /dev/null
+++ b/src/domain/Invoice/Invoice.ts
@@ -0,0 +1,3 @@
+export class Invoice {
+    
+}
\ No newline at end of file
diff --git a/src/domain/Punch/IPunchHandler.ts b/src/domain/Punch/IPunchHandler.ts
new file mode 100644
index 0000000..cdc95d4
--- /dev/null
+++ b/src/domain/Punch/IPunchHandler.ts
@@ -0,0 +1,5 @@
+import { Punch } from "./Punch.ts";
+
+export interface IPunchHandler {
+    createPunchAsync(punch: Punch): Promise<void>;
+}
\ No newline at end of file
diff --git a/src/domain/Punch/Punch.ts b/src/domain/Punch/Punch.ts
new file mode 100644
index 0000000..4b8e105
--- /dev/null
+++ b/src/domain/Punch/Punch.ts
@@ -0,0 +1,15 @@
+import { PunchType } from "./PunchType.ts";
+
+export class Punch {
+    type: PunchType;
+    user: string;
+    punchDir: string;
+    punchFilePath: string;
+
+    constructor(punchType: PunchType, user: string) {
+        this.type = punchType;
+        this.user = user;
+        this.punchDir = `./.timeclock/punches/${user}`;
+        this.punchFilePath = `${this.punchDir}/punch`;
+    }
+}
\ No newline at end of file
diff --git a/src/domain/Punch/PunchType.ts b/src/domain/Punch/PunchType.ts
new file mode 100644
index 0000000..4a1df3f
--- /dev/null
+++ b/src/domain/Punch/PunchType.ts
@@ -0,0 +1,4 @@
+export enum PunchType {
+    Sart,
+    End
+}
\ No newline at end of file
diff --git a/src/domain/Shift/IShiftHandler.ts b/src/domain/Shift/IShiftHandler.ts
new file mode 100644
index 0000000..024bf11
--- /dev/null
+++ b/src/domain/Shift/IShiftHandler.ts
@@ -0,0 +1,5 @@
+import { Shift } from "./Shift.ts";
+
+export interface IShiftHandler {
+    createShiftAsync(shift: Shift): Promise<void>;
+}
\ No newline at end of file
diff --git a/src/domain/Shift/Shift.ts b/src/domain/Shift/Shift.ts
new file mode 100644
index 0000000..3622038
--- /dev/null
+++ b/src/domain/Shift/Shift.ts
@@ -0,0 +1,16 @@
+import * as DomainConstants from "../Constants.ts";
+
+export class Shift {
+    user: string;
+    diffHours: number
+    shiftDir: string;
+    shiftFilePath: string;
+
+    constructor(user: string, punchStartUtcMs: string, punchEndUtcMs: string) {
+        this.user = user;
+        const diffMs: number = Number.parseInt(punchEndUtcMs) - Number.parseInt(punchStartUtcMs);
+        this.diffHours = diffMs/DomainConstants.ONE_HOUR_IN_MS;
+        this.shiftDir = `./.timeclock/shifts/${user}`;
+        this.shiftFilePath = `${this.shiftDir}/shift_${crypto.randomUUID()}`;
+    }
+}
\ No newline at end of file
diff --git a/src/infra/IO/Files.ts b/src/infra/IO/Files.ts
new file mode 100644
index 0000000..ef1f029
--- /dev/null
+++ b/src/infra/IO/Files.ts
@@ -0,0 +1,10 @@
+import {exists} from "https://deno.land/std@0.201.0/fs/mod.ts";
+
+export async function createDirectoryAsync(path: string) {
+    const dirExists = await exists(path);
+    if (!dirExists) {
+        await Deno.mkdir(path, {
+            recursive: true
+        });
+    }
+}
\ No newline at end of file
diff --git a/src/infra/IO/Shell.ts b/src/infra/IO/Shell.ts
new file mode 100644
index 0000000..61825bb
--- /dev/null
+++ b/src/infra/IO/Shell.ts
@@ -0,0 +1,6 @@
+import { ShellOutput } from "./ShellOutput.ts";
+
+export async function executeShellCommandAsync(command: string, args: string[]): Promise<ShellOutput> {
+    const output = await new Deno.Command(command, { args: args }).output();
+    return new ShellOutput(output);
+}
\ No newline at end of file
diff --git a/src/infra/IO/ShellOutput.ts b/src/infra/IO/ShellOutput.ts
new file mode 100644
index 0000000..2db547c
--- /dev/null
+++ b/src/infra/IO/ShellOutput.ts
@@ -0,0 +1,28 @@
+export class ShellOutput {
+    private _output: Deno.CommandOutput;
+
+    constructor(output: Deno.CommandOutput) {
+        this._output = output;
+    }
+    
+    public get code(): number {
+        return this._output.code;
+    }
+
+    public get stderr(): string {
+        return new TextDecoder().decode(this._output.stderr);
+    }
+
+    public get stdout(): string {
+        return new TextDecoder().decode(this._output.stdout);
+    }
+
+    public verifyZeroReturnCode(): ShellOutput {
+        if (this._output.code !== 0) {
+            // todo - enhance error handling
+            console.log(this.stdout, this.stderr);
+            throw `non-zero RC: ${this._output.code}`;
+        }
+        return this;
+    }
+}
\ No newline at end of file
diff --git a/src/timeclock.ts b/src/timeclock.ts
deleted file mode 100644
index d6b70d2..0000000
--- a/src/timeclock.ts
+++ /dev/null
@@ -1,75 +0,0 @@
-enum PunchType {
-    Sart,
-    End
-}
-
-const ONE_HOUR_IN_MS = 3600000;
-
-import {exists} from "https://deno.land/std@0.201.0/fs/mod.ts";
-
-const user: string = Deno.args[0];
-const isEndPunch: boolean = Deno.args.some(x => x === "--end");
-const punchType: PunchType = isEndPunch ? PunchType.End : PunchType.Sart;
-const punchDir = `./.timeclock/punches/${user}`;
-const punchFilePath = `${punchDir}/punch`;
-const shiftDir = `./.timeclock/shifts/${user}`;
-const shiftFilePath = `${shiftDir}/shift_${crypto.randomUUID()}`;
-
-async function executeShellCommand(command: string, args: string[]): Promise<string> {
-    const cmd = new Deno.Command(command, { args: args });
-    const { code, stdout, stderr } = await cmd.output();
-    if (code !== 0) {
-        console.log(new TextDecoder().decode(stdout), new TextDecoder().decode(stderr));
-        throw `non-zero RC: ${code}`;
-    }
-    return new TextDecoder().decode(stdout);
-}
-
-async function createDirectory(path: string) {
-    const dirExists = await exists(path);
-    if (!dirExists) {
-        await Deno.mkdir(path, {
-            recursive: true
-        });
-    }
-}
-
-async function createPunch() {
-    if (punchType === PunchType.Sart) {
-        await createStartPunch();
-    } else {
-        await createEndPunch();
-    }
-}
-
-async function createStartPunch() {
-    await Deno.writeTextFile(punchFilePath, Date.now().toString());
-    await executeShellCommand("git", ["add", punchFilePath]);
-    await executeShellCommand("git", ["commit", "-m", `\"TIMECLOCK PUNCH START - ${user}\"`]);
-}
-
-async function createEndPunch() {
-    await createDirectory(shiftDir);
-    const nowUtcMs = Date.now().toString();
-    const punchStartUtcMs = await Deno.readTextFile(punchFilePath);
-    await Deno.remove(punchFilePath);
-    const diffMs: number = Number.parseInt(nowUtcMs) - Number.parseInt(punchStartUtcMs);
-    const diffHors = diffMs/ONE_HOUR_IN_MS;
-    await Deno.writeTextFile(shiftFilePath, diffHors.toString());
-    await executeShellCommand("git", ["add", punchFilePath]);
-    await executeShellCommand("git", ["add", shiftFilePath]);
-    await executeShellCommand("git", ["commit", "-m", `\"TIMECLOCK PUNCH END - ${user}\"`]);
-}
-
-async function main() {
-    const statusOutput = await executeShellCommand("git", ["status"]);
-    if (!statusOutput.includes("nothing to commit, working tree clean")) {
-        throw "punches must occur on a clean working tree";
-    }
-    else {
-        await createDirectory(punchDir);
-        await createPunch();
-    }
-}
-
-await main();