refactor: Deduplicate time-tracking.service.js (1045 -> 876 lines)

Extract shared helpers:
- validateProjectExists, validateTodoExists, validateCompanyExists,
  validateRelatedEntities (replaces 4x copy-pasted validation blocks)
- generateTimesheetWorkbook (shared workbook creation logic)
- addDailySummary (shared daily totals section)
- saveTimesheetFile (shared file save + DB insert)
- computeDailyTotals, getUserNamePrefix

generateMonthlyTimesheet and generateCompanyTimesheet now use shared
helpers instead of duplicating ~370 lines each.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

src/services/time-tracking.service.js

@@ -43,6 +43,176 @@ const formatDuration = (minutes) => {
   return `${hours}:${String(mins).padStart(2, '0')}`;
 };
 
+// --- Shared entity validation helpers ---
+
+const validateProjectExists = async (projectId) => {
+  const [project] = await db
+    .select()
+    .from(projects)
+    .where(eq(projects.id, projectId))
+    .limit(1);
+  if (!project) throw new NotFoundError('Projekt nenájdený');
+};
+
+const validateTodoExists = async (todoId) => {
+  const [todo] = await db
+    .select()
+    .from(todos)
+    .where(eq(todos.id, todoId))
+    .limit(1);
+  if (!todo) throw new NotFoundError('Todo nenájdené');
+};
+
+const validateCompanyExists = async (companyId) => {
+  const [company] = await db
+    .select()
+    .from(companies)
+    .where(eq(companies.id, companyId))
+    .limit(1);
+  if (!company) throw new NotFoundError('Firma nenájdená');
+  return company;
+};
+
+const validateRelatedEntities = async (projectId, todoId, companyId) => {
+  if (projectId) await validateProjectExists(projectId);
+  if (todoId) await validateTodoExists(todoId);
+  if (companyId) await validateCompanyExists(companyId);
+};
+
+// --- Shared timesheet generation helpers ---
+
+const getUserNamePrefix = (user) => {
+  if (user.firstName && user.lastName) {
+    return `${user.firstName}-${user.lastName}`.toLowerCase().replace(/\s+/g, '-');
+  }
+  if (user.firstName) {
+    return user.firstName.toLowerCase().replace(/\s+/g, '-');
+  }
+  if (user.username) {
+    return user.username.toLowerCase().replace(/\s+/g, '-');
+  }
+  return 'timesheet';
+};
+
+const computeDailyTotals = (entries) => {
+  let totalMinutes = 0;
+  const dailyTotals = {};
+  entries.forEach((entry) => {
+    const minutes = entry.duration || 0;
+    totalMinutes += minutes;
+    const day = formatDate(entry.startTime);
+    dailyTotals[day] = (dailyTotals[day] || 0) + minutes;
+  });
+  return { totalMinutes, dailyTotals };
+};
+
+const generateTimesheetWorkbook = ({ title, headerMeta, columns, headerRowNumber, entries, formatRow }) => {
+  const workbook = new ExcelJS.Workbook();
+  workbook.creator = 'crm-server';
+  const worksheet = workbook.addWorksheet(title, {
+    views: [{ state: 'frozen', ySplit: headerRowNumber }],
+  });
+
+  // Title
+  worksheet.getCell('A1').value = title;
+  worksheet.getCell('A1').font = { name: 'Calibri', size: 16, bold: true };
+  worksheet.mergeCells('A1:D1');
+
+  // Meta rows (Name, Period, etc.)
+  headerMeta.forEach((line, i) => {
+    worksheet.getCell(`A${i + 2}`).value = line;
+  });
+
+  worksheet.columns = columns;
+
+  const headerRow = worksheet.getRow(headerRowNumber);
+  headerRow.values = columns.map((c) => c.header);
+  headerRow.font = { name: 'Calibri', size: 11, bold: true };
+  headerRow.alignment = { vertical: 'middle', horizontal: 'center', wrapText: true };
+  headerRow.fill = { type: 'pattern', pattern: 'solid', fgColor: { argb: 'FFE8EEF5' } };
+  headerRow.height = 20;
+
+  entries.forEach((entry) => {
+    worksheet.addRow(formatRow(entry));
+  });
+
+  // Style body rows
+  worksheet.eachRow((row, rowNumber) => {
+    if (rowNumber >= headerRowNumber) {
+      row.alignment = { vertical: 'middle', wrapText: true };
+    }
+  });
+
+  return { workbook, worksheet };
+};
+
+const addDailySummary = (worksheet, dailyTotals, totalMinutes) => {
+  const summaryStart = worksheet.lastRow.number + 2;
+  worksheet.getCell(`A${summaryStart}`).value = 'Daily totals';
+  worksheet.getCell(`A${summaryStart}`).font = { name: 'Calibri', size: 12, bold: true };
+  worksheet.mergeCells(`A${summaryStart}:B${summaryStart}`);
+
+  const dailyHeaderRowNumber = summaryStart + 1;
+  const dailyHeaderRow = worksheet.getRow(dailyHeaderRowNumber);
+  dailyHeaderRow.values = ['Date', 'Total (h:mm)'];
+  dailyHeaderRow.font = { name: 'Calibri', size: 11, bold: true };
+  dailyHeaderRow.alignment = { vertical: 'middle', horizontal: 'center' };
+  dailyHeaderRow.fill = { type: 'pattern', pattern: 'solid', fgColor: { argb: 'FFE8EEF5' } };
+
+  Object.keys(dailyTotals)
+    .sort()
+    .forEach((day) => {
+      worksheet.addRow([day, formatDuration(dailyTotals[day])]);
+    });
+
+  const overallRow = worksheet.addRow(['Overall total', formatDuration(totalMinutes)]);
+  overallRow.font = { name: 'Calibri', size: 11, bold: true };
+};
+
+const saveTimesheetFile = async (workbook, { userId, year, month, filename }) => {
+  const uploadsDir = path.join(
+    process.cwd(),
+    'uploads',
+    'timesheets',
+    userId.toString(),
+    year.toString(),
+    month.toString()
+  );
+  await fs.mkdir(uploadsDir, { recursive: true });
+
+  const filePath = path.join(uploadsDir, filename);
+  let savedFilePath = null;
+
+  try {
+    await workbook.xlsx.writeFile(filePath);
+    savedFilePath = filePath;
+    const { size: fileSize } = await fs.stat(filePath);
+
+    const [newTimesheet] = await db
+      .insert(timesheets)
+      .values({
+        userId,
+        fileName: filename,
+        filePath,
+        fileType: 'xlsx',
+        fileSize,
+        year,
+        month,
+        isGenerated: true,
+      })
+      .returning();
+
+    return newTimesheet;
+  } catch (error) {
+    if (savedFilePath) {
+      await fs.unlink(savedFilePath).catch(() => {});
+    }
+    throw error;
+  }
+};
+
+// --- Public API ---
+
 /**
  * Start a new time entry
  */
@@ -62,7 +232,6 @@ export const startTimeEntry = async (userId, data) => {
   // Automatically stop existing running timer
   if (existingRunning) {
     const endTime = new Date();
-    // Account for any active pause and accumulated pause duration
     let totalPausedSeconds = existingRunning.pausedDuration || 0;
     if (existingRunning.pausedAt) {
       totalPausedSeconds += Math.floor((endTime - new Date(existingRunning.pausedAt)) / 1000);
@@ -81,44 +250,7 @@ export const startTimeEntry = async (userId, data) => {
       .where(eq(timeEntries.id, existingRunning.id));
   }
 
-  // Verify project exists if provided
-  if (projectId) {
-    const [project] = await db
-      .select()
-      .from(projects)
-      .where(eq(projects.id, projectId))
-      .limit(1);
-
-    if (!project) {
-      throw new NotFoundError('Projekt nenájdený');
-    }
-  }
-
-  // Verify todo exists if provided
-  if (todoId) {
-    const [todo] = await db
-      .select()
-      .from(todos)
-      .where(eq(todos.id, todoId))
-      .limit(1);
-
-    if (!todo) {
-      throw new NotFoundError('Todo nenájdené');
-    }
-  }
-
-  // Verify company exists if provided
-  if (companyId) {
-    const [company] = await db
-      .select()
-      .from(companies)
-      .where(eq(companies.id, companyId))
-      .limit(1);
-
-    if (!company) {
-      throw new NotFoundError('Firma nenájdená');
-    }
-  }
+  await validateRelatedEntities(projectId, todoId, companyId);
 
   const [newEntry] = await db
     .insert(timeEntries)
@@ -150,7 +282,6 @@ export const stopTimeEntry = async (entryId, userId, data = {}) => {
 
   const entry = await getTimeEntryById(entryId);
 
-  // Verify ownership
   if (entry.userId !== userId) {
     throw new BadRequestError('Nemáte oprávnenie zastaviť tento časovač');
   }
@@ -160,49 +291,13 @@ export const stopTimeEntry = async (entryId, userId, data = {}) => {
   }
 
   const endTime = new Date();
-  // Account for any active pause and accumulated pause duration
   let totalPausedSeconds = entry.pausedDuration || 0;
   if (entry.pausedAt) {
     totalPausedSeconds += Math.floor((endTime - new Date(entry.pausedAt)) / 1000);
   }
   const durationInMinutes = Math.round(((endTime - new Date(entry.startTime)) / 60000) - (totalPausedSeconds / 60));
 
-  // Verify related entities if provided (skip validation for null/undefined)
-  if (projectId) {
-    const [project] = await db
-      .select()
-      .from(projects)
-      .where(eq(projects.id, projectId))
-      .limit(1);
-
-    if (!project) {
-      throw new NotFoundError('Projekt nenájdený');
-    }
-  }
-
-  if (todoId) {
-    const [todo] = await db
-      .select()
-      .from(todos)
-      .where(eq(todos.id, todoId))
-      .limit(1);
-
-    if (!todo) {
-      throw new NotFoundError('Todo nenájdené');
-    }
-  }
-
-  if (companyId) {
-    const [company] = await db
-      .select()
-      .from(companies)
-      .where(eq(companies.id, companyId))
-      .limit(1);
-
-    if (!company) {
-      throw new NotFoundError('Firma nenájdená');
-    }
-  }
+  await validateRelatedEntities(projectId, todoId, companyId);
 
   const [updated] = await db
     .update(timeEntries)
@@ -405,18 +500,12 @@ export const generateMonthlyTimesheet = async (userId, year, month) => {
   const endDate = new Date(year, month, 0, 23, 59, 59, 999);
 
   const [user] = await db
-    .select({
-      username: users.username,
-      firstName: users.firstName,
-      lastName: users.lastName,
-    })
+    .select({ username: users.username, firstName: users.firstName, lastName: users.lastName })
     .from(users)
     .where(eq(users.id, userId))
     .limit(1);
 
-  if (!user) {
-    throw new NotFoundError('Používateľ nenájdený');
-  }
+  if (!user) throw new NotFoundError('Používateľ nenájdený');
 
   const entries = await db
     .select({
@@ -447,63 +536,33 @@ export const generateMonthlyTimesheet = async (userId, year, month) => {
     throw new NotFoundError('Žiadne dokončené záznamy pre daný mesiac');
   }
 
-  let totalMinutes = 0;
-  const dailyTotals = {};
-
-  completedEntries.forEach((entry) => {
-    const minutes = entry.duration || 0;
-    totalMinutes += minutes;
-    const day = formatDate(entry.startTime);
-    dailyTotals[day] = (dailyTotals[day] || 0) + minutes;
-  });
-
-  const workbook = new ExcelJS.Workbook();
-  workbook.creator = 'crm-server';
-  const worksheet = workbook.addWorksheet('Timesheet', {
-    views: [{ state: 'frozen', ySplit: 6 }],
-  });
+  const { totalMinutes, dailyTotals } = computeDailyTotals(completedEntries);
 
   const fullName = [user.firstName, user.lastName].filter(Boolean).join(' ') || user.username;
   const periodLabel = `${year}-${String(month).padStart(2, '0')}`;
 
-  worksheet.getCell('A1').value = 'Timesheet';
-  worksheet.getCell('A1').font = { name: 'Calibri', size: 16, bold: true };
-  worksheet.mergeCells('A1:D1');
-
-  worksheet.getCell('A2').value = `Name: ${fullName}`;
-  worksheet.getCell('A3').value = `Period: ${periodLabel}`;
-  worksheet.getCell('A4').value = `Generated: ${new Date().toLocaleString()}`;
-
-  worksheet.columns = [
-    { key: 'date', width: 12 },
-    { key: 'project', width: 28 },
-    { key: 'todo', width: 28 },
-    { key: 'company', width: 24 },
-    { key: 'description', width: 40 },
-    { key: 'start', width: 12 },
-    { key: 'end', width: 12 },
-    { key: 'duration', width: 16 },
+  const columns = [
+    { key: 'date', header: 'Date', width: 12 },
+    { key: 'project', header: 'Project', width: 28 },
+    { key: 'todo', header: 'Todo', width: 28 },
+    { key: 'company', header: 'Company', width: 24 },
+    { key: 'description', header: 'Description', width: 40 },
+    { key: 'start', header: 'Start', width: 12 },
+    { key: 'end', header: 'End', width: 12 },
+    { key: 'duration', header: 'Duration (h:mm)', width: 16 },
   ];
 
-  const headerRowNumber = 6;
-  const headerRow = worksheet.getRow(headerRowNumber);
-  headerRow.values = [
-    'Date',
-    'Project',
-    'Todo',
-    'Company',
-    'Description',
-    'Start',
-    'End',
-    'Duration (h:mm)',
-  ];
-  headerRow.font = { name: 'Calibri', size: 11, bold: true };
-  headerRow.alignment = { vertical: 'middle', horizontal: 'center', wrapText: true };
-  headerRow.fill = { type: 'pattern', pattern: 'solid', fgColor: { argb: 'FFE8EEF5' } };
-  headerRow.height = 20;
-
-  completedEntries.forEach((entry) => {
-    worksheet.addRow({
+  const { workbook, worksheet } = generateTimesheetWorkbook({
+    title: 'Timesheet',
+    headerMeta: [
+      `Name: ${fullName}`,
+      `Period: ${periodLabel}`,
+      `Generated: ${new Date().toLocaleString()}`,
+    ],
+    columns,
+    headerRowNumber: 6,
+    entries: completedEntries,
+    formatRow: (entry) => ({
       date: formatDate(entry.startTime),
       project: entry.projectName || '',
       todo: entry.todoTitle || '',
@@ -512,104 +571,33 @@ export const generateMonthlyTimesheet = async (userId, year, month) => {
       start: formatTime(entry.startTime),
       end: formatTime(entry.endTime),
       duration: formatDuration(entry.duration),
-    });
+    }),
   });
 
-  // Style body rows
-  worksheet.eachRow((row, rowNumber) => {
-    if (rowNumber >= headerRowNumber) {
-      row.alignment = { vertical: 'middle', wrapText: true };
-    }
-  });
+  addDailySummary(worksheet, dailyTotals, totalMinutes);
 
-  let summaryStart = worksheet.lastRow.number + 2;
-  worksheet.getCell(`A${summaryStart}`).value = 'Daily totals';
-  worksheet.getCell(`A${summaryStart}`).font = { name: 'Calibri', size: 12, bold: true };
-  worksheet.mergeCells(`A${summaryStart}:B${summaryStart}`);
-
-  const dailyHeaderRowNumber = summaryStart + 1;
-  const dailyHeaderRow = worksheet.getRow(dailyHeaderRowNumber);
-  dailyHeaderRow.values = ['Date', 'Total (h:mm)'];
-  dailyHeaderRow.font = { name: 'Calibri', size: 11, bold: true };
-  dailyHeaderRow.alignment = { vertical: 'middle', horizontal: 'center' };
-  dailyHeaderRow.fill = { type: 'pattern', pattern: 'solid', fgColor: { argb: 'FFE8EEF5' } };
-
-  Object.keys(dailyTotals)
-    .sort()
-    .forEach((day) => {
-      worksheet.addRow([day, formatDuration(dailyTotals[day])]);
-    });
-
-  const overallRow = worksheet.addRow(['Overall total', formatDuration(totalMinutes)]);
-  overallRow.font = { name: 'Calibri', size: 11, bold: true };
-
-  const uploadsDir = path.join(
-    process.cwd(),
-    'uploads',
-    'timesheets',
-    userId.toString(),
-    year.toString(),
-    month.toString()
-  );
-  await fs.mkdir(uploadsDir, { recursive: true });
-
-  // Generate user-friendly filename
-  let namePrefix;
-  if (user.firstName && user.lastName) {
-    namePrefix = `${user.firstName}-${user.lastName}`.toLowerCase().replace(/\s+/g, '-');
-  } else if (user.firstName) {
-    namePrefix = user.firstName.toLowerCase().replace(/\s+/g, '-');
-  } else if (user.username) {
-    namePrefix = user.username.toLowerCase().replace(/\s+/g, '-');
-  } else {
-    namePrefix = 'timesheet';
-  }
+  const namePrefix = getUserNamePrefix(user);
   const filename = `${namePrefix}-vykazprace-${periodLabel}.xlsx`;
-  const filePath = path.join(uploadsDir, filename);
-  let savedFilePath = null;
 
-  try {
-    await workbook.xlsx.writeFile(filePath);
-    savedFilePath = filePath;
-    const { size: fileSize } = await fs.stat(filePath);
+  const newTimesheet = await saveTimesheetFile(workbook, { userId, year, month, filename });
 
-    const [newTimesheet] = await db
-      .insert(timesheets)
-      .values({
-        userId,
-        fileName: filename,
-        filePath,
-        fileType: 'xlsx',
-        fileSize,
-        year,
-        month,
-        isGenerated: true,
-      })
-      .returning();
-
-    return {
-      timesheet: {
-        id: newTimesheet.id,
-        fileName: newTimesheet.fileName,
-        fileType: newTimesheet.fileType,
-        fileSize: newTimesheet.fileSize,
-        year: newTimesheet.year,
-        month: newTimesheet.month,
-        isGenerated: newTimesheet.isGenerated,
-        uploadedAt: newTimesheet.uploadedAt,
-      },
-      totals: {
-        totalMinutes,
-        totalFormatted: formatDuration(totalMinutes),
-        daily: dailyTotals,
-      },
-    };
-  } catch (error) {
-    if (savedFilePath) {
-      await fs.unlink(savedFilePath).catch(() => {});
-    }
-    throw error;
-  }
+  return {
+    timesheet: {
+      id: newTimesheet.id,
+      fileName: newTimesheet.fileName,
+      fileType: newTimesheet.fileType,
+      fileSize: newTimesheet.fileSize,
+      year: newTimesheet.year,
+      month: newTimesheet.month,
+      isGenerated: newTimesheet.isGenerated,
+      uploadedAt: newTimesheet.uploadedAt,
+    },
+    totals: {
+      totalMinutes,
+      totalFormatted: formatDuration(totalMinutes),
+      daily: dailyTotals,
+    },
+  };
 };
 
 /**
@@ -619,7 +607,6 @@ export const updateTimeEntry = async (entryId, actor, data) => {
   const { userId, role } = actor;
   const entry = await getTimeEntryById(entryId);
 
-  // Verify ownership (admin can edit anyone)
   if (entry.userId !== userId && role !== 'admin') {
     throw new ForbiddenError('Nemáte oprávnenie upraviť tento záznam');
   }
@@ -634,42 +621,7 @@ export const updateTimeEntry = async (entryId, actor, data) => {
   const companyId = normalizeOptionalId(data.companyId);
   const description = normalizeOptionalText(data.description);
 
-  // Verify related entities if being changed
-  if (projectId) {
-    const [project] = await db
-      .select()
-      .from(projects)
-      .where(eq(projects.id, projectId))
-      .limit(1);
-
-    if (!project) {
-      throw new NotFoundError('Projekt nenájdený');
-    }
-  }
-
-  if (todoId) {
-    const [todo] = await db
-      .select()
-      .from(todos)
-      .where(eq(todos.id, todoId))
-      .limit(1);
-
-    if (!todo) {
-      throw new NotFoundError('Todo nenájdené');
-    }
-  }
-
-  if (companyId) {
-    const [company] = await db
-      .select()
-      .from(companies)
-      .where(eq(companies.id, companyId))
-      .limit(1);
-
-    if (!company) {
-      throw new NotFoundError('Firma nenájdená');
-    }
-  }
+  await validateRelatedEntities(projectId, todoId, companyId);
 
   // Calculate new duration if times are changed
   let newDuration = entry.duration;
@@ -710,7 +662,6 @@ export const deleteTimeEntry = async (entryId, actor) => {
   const { userId, role } = actor;
   const entry = await getTimeEntryById(entryId);
 
-  // Verify ownership (admin can delete anyone)
   if (entry.userId !== userId && role !== 'admin') {
     throw new ForbiddenError('Nemáte oprávnenie odstrániť tento záznam');
   }
@@ -730,7 +681,6 @@ export const deleteTimeEntry = async (entryId, actor) => {
 export const getTimeEntryWithRelations = async (entryId) => {
   const entry = await getTimeEntryById(entryId);
 
-  // Get project if exists
   let project = null;
   if (entry.projectId) {
     [project] = await db
@@ -740,7 +690,6 @@ export const getTimeEntryWithRelations = async (entryId) => {
       .limit(1);
   }
 
-  // Get todo if exists
   let todo = null;
   if (entry.todoId) {
     [todo] = await db
@@ -750,7 +699,6 @@ export const getTimeEntryWithRelations = async (entryId) => {
       .limit(1);
   }
 
-  // Get company if exists
   let company = null;
   if (entry.companyId) {
     [company] = await db
@@ -776,28 +724,14 @@ export const generateCompanyTimesheet = async (userId, year, month, companyId) =
   const endDate = new Date(year, month, 0, 23, 59, 59, 999);
 
   const [user] = await db
-    .select({
-      username: users.username,
-      firstName: users.firstName,
-      lastName: users.lastName,
-    })
+    .select({ username: users.username, firstName: users.firstName, lastName: users.lastName })
     .from(users)
     .where(eq(users.id, userId))
     .limit(1);
 
-  if (!user) {
-    throw new NotFoundError('Používateľ nenájdený');
-  }
+  if (!user) throw new NotFoundError('Používateľ nenájdený');
 
-  const [company] = await db
-    .select()
-    .from(companies)
-    .where(eq(companies.id, companyId))
-    .limit(1);
-
-  if (!company) {
-    throw new NotFoundError('Firma nenájdená');
-  }
+  const company = await validateCompanyExists(companyId);
 
   const entries = await db
     .select({
@@ -827,62 +761,33 @@ export const generateCompanyTimesheet = async (userId, year, month, companyId) =
     throw new NotFoundError('Žiadne dokončené záznamy pre danú firmu a mesiac');
   }
 
-  let totalMinutes = 0;
-  const dailyTotals = {};
-
-  completedEntries.forEach((entry) => {
-    const minutes = entry.duration || 0;
-    totalMinutes += minutes;
-    const day = formatDate(entry.startTime);
-    dailyTotals[day] = (dailyTotals[day] || 0) + minutes;
-  });
-
-  const workbook = new ExcelJS.Workbook();
-  workbook.creator = 'crm-server';
-  const worksheet = workbook.addWorksheet('Company Timesheet', {
-    views: [{ state: 'frozen', ySplit: 7 }],
-  });
+  const { totalMinutes, dailyTotals } = computeDailyTotals(completedEntries);
 
   const fullName = [user.firstName, user.lastName].filter(Boolean).join(' ') || user.username;
   const periodLabel = `${year}-${String(month).padStart(2, '0')}`;
 
-  worksheet.getCell('A1').value = 'Company Timesheet';
-  worksheet.getCell('A1').font = { name: 'Calibri', size: 16, bold: true };
-  worksheet.mergeCells('A1:D1');
-
-  worksheet.getCell('A2').value = `Company: ${company.name}`;
-  worksheet.getCell('A3').value = `Employee: ${fullName}`;
-  worksheet.getCell('A4').value = `Period: ${periodLabel}`;
-  worksheet.getCell('A5').value = `Generated: ${new Date().toLocaleString()}`;
-
-  worksheet.columns = [
-    { key: 'date', width: 12 },
-    { key: 'project', width: 28 },
-    { key: 'todo', width: 28 },
-    { key: 'description', width: 40 },
-    { key: 'start', width: 12 },
-    { key: 'end', width: 12 },
-    { key: 'duration', width: 16 },
+  const columns = [
+    { key: 'date', header: 'Date', width: 12 },
+    { key: 'project', header: 'Project', width: 28 },
+    { key: 'todo', header: 'Todo', width: 28 },
+    { key: 'description', header: 'Description', width: 40 },
+    { key: 'start', header: 'Start', width: 12 },
+    { key: 'end', header: 'End', width: 12 },
+    { key: 'duration', header: 'Duration (h:mm)', width: 16 },
   ];
 
-  const headerRowNumber = 7;
-  const headerRow = worksheet.getRow(headerRowNumber);
-  headerRow.values = [
-    'Date',
-    'Project',
-    'Todo',
-    'Description',
-    'Start',
-    'End',
-    'Duration (h:mm)',
-  ];
-  headerRow.font = { name: 'Calibri', size: 11, bold: true };
-  headerRow.alignment = { vertical: 'middle', horizontal: 'center', wrapText: true };
-  headerRow.fill = { type: 'pattern', pattern: 'solid', fgColor: { argb: 'FFE8EEF5' } };
-  headerRow.height = 20;
-
-  completedEntries.forEach((entry) => {
-    worksheet.addRow({
+  const { workbook, worksheet } = generateTimesheetWorkbook({
+    title: 'Company Timesheet',
+    headerMeta: [
+      `Company: ${company.name}`,
+      `Employee: ${fullName}`,
+      `Period: ${periodLabel}`,
+      `Generated: ${new Date().toLocaleString()}`,
+    ],
+    columns,
+    headerRowNumber: 7,
+    entries: completedEntries,
+    formatRow: (entry) => ({
       date: formatDate(entry.startTime),
       project: entry.projectName || '',
       todo: entry.todoTitle || '',
@@ -890,106 +795,35 @@ export const generateCompanyTimesheet = async (userId, year, month, companyId) =
       start: formatTime(entry.startTime),
       end: formatTime(entry.endTime),
       duration: formatDuration(entry.duration),
-    });
+    }),
   });
 
-  // Style body rows
-  worksheet.eachRow((row, rowNumber) => {
-    if (rowNumber >= headerRowNumber) {
-      row.alignment = { vertical: 'middle', wrapText: true };
-    }
-  });
+  addDailySummary(worksheet, dailyTotals, totalMinutes);
 
-  let summaryStart = worksheet.lastRow.number + 2;
-  worksheet.getCell(`A${summaryStart}`).value = 'Daily totals';
-  worksheet.getCell(`A${summaryStart}`).font = { name: 'Calibri', size: 12, bold: true };
-  worksheet.mergeCells(`A${summaryStart}:B${summaryStart}`);
-
-  const dailyHeaderRowNumber = summaryStart + 1;
-  const dailyHeaderRow = worksheet.getRow(dailyHeaderRowNumber);
-  dailyHeaderRow.values = ['Date', 'Total (h:mm)'];
-  dailyHeaderRow.font = { name: 'Calibri', size: 11, bold: true };
-  dailyHeaderRow.alignment = { vertical: 'middle', horizontal: 'center' };
-  dailyHeaderRow.fill = { type: 'pattern', pattern: 'solid', fgColor: { argb: 'FFE8EEF5' } };
-
-  Object.keys(dailyTotals)
-    .sort()
-    .forEach((day) => {
-      worksheet.addRow([day, formatDuration(dailyTotals[day])]);
-    });
-
-  const overallRow = worksheet.addRow(['Overall total', formatDuration(totalMinutes)]);
-  overallRow.font = { name: 'Calibri', size: 11, bold: true };
-
-  const uploadsDir = path.join(
-    process.cwd(),
-    'uploads',
-    'timesheets',
-    userId.toString(),
-    year.toString(),
-    month.toString()
-  );
-  await fs.mkdir(uploadsDir, { recursive: true });
-
-  // Generate user-friendly filename
-  let namePrefix;
-  if (user.firstName && user.lastName) {
-    namePrefix = `${user.firstName}-${user.lastName}`.toLowerCase().replace(/\s+/g, '-');
-  } else if (user.firstName) {
-    namePrefix = user.firstName.toLowerCase().replace(/\s+/g, '-');
-  } else if (user.username) {
-    namePrefix = user.username.toLowerCase().replace(/\s+/g, '-');
-  } else {
-    namePrefix = 'timesheet';
-  }
+  const namePrefix = getUserNamePrefix(user);
   const companySlug = company.name.replace(/[^a-zA-Z0-9]/g, '_').toLowerCase();
   const filename = `${namePrefix}-vykazprace-${companySlug}-${periodLabel}.xlsx`;
-  const filePath = path.join(uploadsDir, filename);
-  let savedFilePath = null;
 
-  try {
-    await workbook.xlsx.writeFile(filePath);
-    savedFilePath = filePath;
-    const { size: fileSize } = await fs.stat(filePath);
+  const newTimesheet = await saveTimesheetFile(workbook, { userId, year, month, filename });
 
-    const [newTimesheet] = await db
-      .insert(timesheets)
-      .values({
-        userId,
-        fileName: filename,
-        filePath,
-        fileType: 'xlsx',
-        fileSize,
-        year,
-        month,
-        isGenerated: true,
-      })
-      .returning();
-
-    return {
-      timesheet: {
-        id: newTimesheet.id,
-        fileName: newTimesheet.fileName,
-        fileType: newTimesheet.fileType,
-        fileSize: newTimesheet.fileSize,
-        year: newTimesheet.year,
-        month: newTimesheet.month,
-        isGenerated: newTimesheet.isGenerated,
-        uploadedAt: newTimesheet.uploadedAt,
-      },
-      companyName: company.name,
-      totals: {
-        totalMinutes,
-        totalFormatted: formatDuration(totalMinutes),
-        daily: dailyTotals,
-      },
-    };
-  } catch (error) {
-    if (savedFilePath) {
-      await fs.unlink(savedFilePath).catch(() => {});
-    }
-    throw error;
-  }
+  return {
+    timesheet: {
+      id: newTimesheet.id,
+      fileName: newTimesheet.fileName,
+      fileType: newTimesheet.fileType,
+      fileSize: newTimesheet.fileSize,
+      year: newTimesheet.year,
+      month: newTimesheet.month,
+      isGenerated: newTimesheet.isGenerated,
+      uploadedAt: newTimesheet.uploadedAt,
+    },
+    companyName: company.name,
+    totals: {
+      totalMinutes,
+      totalFormatted: formatDuration(totalMinutes),
+      daily: dailyTotals,
+    },
+  };
 };
 
 /**
@@ -998,19 +832,16 @@ export const generateCompanyTimesheet = async (userId, year, month, companyId) =
 export const getMonthlyStats = async (userId, year, month) => {
   const entries = await getMonthlyTimeEntries(userId, year, month);
 
-  // Total time in minutes
   const totalMinutes = entries.reduce((sum, entry) => {
     return sum + (entry.duration || 0);
   }, 0);
 
-  // Count of days worked
   const uniqueDays = new Set(
     entries
       .filter((e) => !e.isRunning)
       .map((e) => new Date(e.startTime).toDateString())
   ).size;
 
-  // Time by project
   const byProject = {};
   entries.forEach((entry) => {
     if (entry.projectId && entry.duration) {
@@ -1021,7 +852,6 @@ export const getMonthlyStats = async (userId, year, month) => {
     }
   });
 
-  // Time by company
   const byCompany = {};
   entries.forEach((entry) => {
     if (entry.companyId && entry.duration) {