Generate invoice PDFs

1 files changed, 239 insertions, 0 deletions

diff --git a/internal/reports/invoice.go b/internal/reports/invoice.go
new file mode 100644
index 0000000..73235d5
--- /dev/null
+++ b/internal/reports/invoice.go
@@ -0,0 +1,239 @@
+package reports
+
+import (
+	"database/sql"
+	"fmt"
+	"time"
+
+	"punchcard/internal/queries"
+)
+
+type InvoiceData struct {
+	ClientID        int64
+	ClientName      string
+	ProjectName     string
+	ContractorName  string
+	ContractorLabel string
+	ContractorEmail string
+	InvoiceNumber   int64
+	DateRange       DateRange
+	LineItems       []LineItem
+	TotalHours      float64
+	TotalAmount     float64
+	GeneratedDate   time.Time
+}
+
+type LineItem struct {
+	Description string  `json:"description"`
+	Hours       float64 `json:"hours"`
+	Rate        float64 `json:"rate"`
+	Amount      float64 `json:"amount"`
+}
+
+type RateSource string
+
+const (
+	RateSourceEntry   RateSource = "entry"
+	RateSourceProject RateSource = "project"
+	RateSourceClient  RateSource = "client"
+)
+
+type timeEntryData struct {
+	TimeEntryID         int64
+	StartTime           time.Time
+	EndTime             sql.NullTime
+	Description         sql.NullString
+	EntryBillableRate   sql.NullInt64
+	ClientID            int64
+	ClientName          string
+	ClientBillableRate  sql.NullInt64
+	ProjectID           sql.NullInt64
+	ProjectName         sql.NullString
+	ProjectBillableRate sql.NullInt64
+	DurationSeconds     int64
+	RateSource          string
+}
+
+func GenerateInvoiceData(
+	entries interface{},
+	clientID int64,
+	clientName,
+	projectName string,
+	contractor queries.Contractor,
+	number int64,
+	dateRange DateRange,
+) (*InvoiceData, error) {
+	var timeEntries []timeEntryData
+
+	switch e := entries.(type) {
+	case []queries.GetInvoiceDataByClientRow:
+		for _, entry := range e {
+			timeEntries = append(timeEntries, timeEntryData{
+				TimeEntryID:         entry.TimeEntryID,
+				StartTime:           entry.StartTime,
+				EndTime:             entry.EndTime,
+				Description:         entry.Description,
+				EntryBillableRate:   entry.EntryBillableRate,
+				ClientID:            entry.ClientID,
+				ClientName:          entry.ClientName,
+				ClientBillableRate:  entry.ClientBillableRate,
+				ProjectID:           entry.ProjectID,
+				ProjectName:         entry.ProjectName,
+				ProjectBillableRate: entry.ProjectBillableRate,
+				DurationSeconds:     entry.DurationSeconds,
+				RateSource:          entry.RateSource,
+			})
+		}
+	case []queries.GetInvoiceDataByProjectRow:
+		for _, entry := range e {
+			timeEntries = append(timeEntries, timeEntryData{
+				TimeEntryID:         entry.TimeEntryID,
+				StartTime:           entry.StartTime,
+				EndTime:             entry.EndTime,
+				Description:         entry.Description,
+				EntryBillableRate:   entry.EntryBillableRate,
+				ClientID:            entry.ClientID,
+				ClientName:          entry.ClientName,
+				ClientBillableRate:  entry.ClientBillableRate,
+				ProjectID:           sql.NullInt64{Int64: entry.ProjectID, Valid: true},
+				ProjectName:         sql.NullString{String: entry.ProjectName, Valid: true},
+				ProjectBillableRate: entry.ProjectBillableRate,
+				DurationSeconds:     entry.DurationSeconds,
+				RateSource:          entry.RateSource,
+			})
+		}
+	default:
+		return nil, fmt.Errorf("unsupported entry type")
+	}
+
+	lineItems := groupTimeEntriesIntoLineItems(timeEntries)
+
+	totalHours := 0.0
+	totalAmount := 0.0
+	for _, item := range lineItems {
+		totalHours += item.Hours
+		totalAmount += item.Amount
+	}
+
+	invoice := &InvoiceData{
+		ClientID:        clientID,
+		ClientName:      clientName,
+		ProjectName:     projectName,
+		ContractorName:  contractor.Name,
+		ContractorLabel: contractor.Label,
+		ContractorEmail: contractor.Email,
+		InvoiceNumber:   number,
+		DateRange:       dateRange,
+		LineItems:       lineItems,
+		TotalHours:      totalHours,
+		TotalAmount:     totalAmount,
+		GeneratedDate:   time.Now().UTC(),
+	}
+
+	return invoice, nil
+}
+
+func groupTimeEntriesIntoLineItems(entries []timeEntryData) []LineItem {
+	var lineItems []LineItem
+
+	// Group 1: Entries with overridden rates
+	entryRateGroups := make(map[int64][]timeEntryData)
+
+	// Group 2: Entries using project rates
+	projectRateGroups := make(map[int64][]timeEntryData)
+
+	// Group 3: Entries using client rates
+	clientRateGroups := make(map[int64][]timeEntryData)
+
+	for _, entry := range entries {
+		switch RateSource(entry.RateSource) {
+		case RateSourceEntry:
+			rate := entry.EntryBillableRate.Int64
+			entryRateGroups[rate] = append(entryRateGroups[rate], entry)
+		case RateSourceProject:
+			if entry.ProjectID.Valid {
+				projectRateGroups[entry.ProjectID.Int64] = append(projectRateGroups[entry.ProjectID.Int64], entry)
+			}
+		case RateSourceClient:
+			clientRateGroups[entry.ClientID] = append(clientRateGroups[entry.ClientID], entry)
+		}
+	}
+
+	// Process overridden rates first
+	for rate, entries := range entryRateGroups {
+		if len(entries) > 0 {
+			lineItem := createLineItem(entries, rate, "Custom rate work")
+			lineItems = append(lineItems, lineItem)
+		}
+	}
+
+	// Process project rates
+	for _, entries := range projectRateGroups {
+		if len(entries) > 0 {
+			projectName := "Unknown Project"
+			rateCents := int64(0)
+			if entries[0].ProjectName.Valid {
+				projectName = entries[0].ProjectName.String
+			}
+			if entries[0].ProjectBillableRate.Valid {
+				rateCents = entries[0].ProjectBillableRate.Int64
+			}
+
+			lineItem := createLineItem(entries, rateCents, projectName)
+			lineItems = append(lineItems, lineItem)
+		}
+	}
+
+	// Process client rates
+	for _, entries := range clientRateGroups {
+		if len(entries) > 0 {
+			clientName := entries[0].ClientName
+			rateCents := int64(0)
+			if entries[0].ClientBillableRate.Valid {
+				rateCents = entries[0].ClientBillableRate.Int64
+			}
+
+			lineItem := createLineItem(entries, rateCents, fmt.Sprintf("General work - %s", clientName))
+			lineItems = append(lineItems, lineItem)
+		}
+	}
+
+	return lineItems
+}
+
+func createLineItem(entries []timeEntryData, hourlyRateCents int64, description string) LineItem {
+	totalSeconds := int64(0)
+	for _, entry := range entries {
+		totalSeconds += entry.DurationSeconds
+	}
+
+	// Calculate whole hours and remaining seconds using integer arithmetic
+	wholeHours := totalSeconds / 3600
+	remainingSeconds := totalSeconds % 3600
+
+	// Calculate amount for whole hours (integer arithmetic, result in cents)
+	wholeHoursAmountCents := wholeHours * hourlyRateCents
+
+	// Calculate amount for partial hour, rounded down to the minute
+	// First convert remaining seconds to whole minutes (truncate seconds)
+	partialMinutes := remainingSeconds / 60
+	// Calculate amount for those whole minutes (integer arithmetic)
+	partialHourAmountCents := partialMinutes * hourlyRateCents / 60
+
+	// Total amount in cents, then convert to dollars
+	totalAmountCents := wholeHoursAmountCents + partialHourAmountCents
+	amount := float64(totalAmountCents) / 100.0
+
+	// Convert total seconds to hours for display
+	hours := float64(totalSeconds) / 3600.0
+
+	// Convert rate to dollars for display
+	hourlyRate := float64(hourlyRateCents) / 100.0
+
+	return LineItem{
+		Description: description,
+		Hours:       hours,
+		Rate:        hourlyRate,
+		Amount:      amount,
+	}
+}