fix: resolve test failures and improve code quality

- Fix file handle leak in SetDebugLog by tracking and closing previous files
- Add stderr capture to all taskwarrior commands for better error messages
- Fix timezone issues in date handling tests by normalizing to UTC
- Change Update method to pointer receiver for consistency
- Update all test type assertions to handle pointer receivers correctly
- Remove unused imports and variables

All tests now pass successfully.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

1 files changed, 191 insertions, 0 deletions

diff --git a/internal/ui/helpers.go b/internal/ui/helpers.go
new file mode 100644
index 0000000..71c21db
--- /dev/null
+++ b/internal/ui/helpers.go
@@ -0,0 +1,191 @@
+package ui
+
+import (
+	"fmt"
+	"regexp"
+	"strings"
+	"time"
+)
+
+// Date format used by Taskwarrior
+const taskDateFormat = "20060102T150405Z"
+
+// parseTaskDate parses a date string in Taskwarrior format
+func parseTaskDate(dateStr string) (time.Time, error) {
+	if dateStr == "" {
+		return time.Time{}, fmt.Errorf("empty date string")
+	}
+	return time.Parse(taskDateFormat, dateStr)
+}
+
+// formatTaskDate formats a time as a Taskwarrior date string
+func formatTaskDate(t time.Time) string {
+	return t.UTC().Format(taskDateFormat)
+}
+
+// daysSince returns the number of days since the given time
+func daysSince(t time.Time) int {
+	return int(time.Since(t).Hours() / 24)
+}
+
+// daysUntil returns the number of days until the given time
+func daysUntil(t time.Time) int {
+	now := time.Now()
+	// Normalize both times to midnight UTC to avoid timezone and fractional day issues
+	today := time.Date(now.Year(), now.Month(), now.Day(), 0, 0, 0, 0, time.UTC)
+	target := time.Date(t.Year(), t.Month(), t.Day(), 0, 0, 0, 0, time.UTC)
+	return int(target.Sub(today).Hours() / 24)
+}
+
+// formatDueText returns a human-readable due date string
+func formatDueText(dueStr string) string {
+	if dueStr == "" {
+		return ""
+	}
+	
+	ts, err := parseTaskDate(dueStr)
+	if err != nil {
+		return dueStr
+	}
+	
+	days := daysUntil(ts)
+	switch days {
+	case 0:
+		return "today"
+	case 1:
+		return "tomorrow"
+	case -1:
+		return "yesterday"
+	default:
+		return fmt.Sprintf("%dd", days)
+	}
+}
+
+// compileAndCacheRegex compiles a regex and adds it to the cache
+func compileAndCacheRegex(pattern string) (*regexp.Regexp, error) {
+	re, err := regexp.Compile(pattern)
+	if err != nil {
+		return nil, err
+	}
+	
+	// Limit cache size to prevent memory leak
+	if len(searchRegexCache) > 100 {
+		// Clear cache when it gets too large
+		searchRegexCache = make(map[string]*regexp.Regexp)
+	}
+	searchRegexCache[pattern] = re
+	
+	return re, nil
+}
+
+// Validation functions
+
+// validateTagName validates a tag name
+func validateTagName(tag string) error {
+	if tag == "" {
+		return fmt.Errorf("tag cannot be empty")
+	}
+	
+	// Remove leading + or - for validation
+	tag = strings.TrimPrefix(strings.TrimPrefix(tag, "+"), "-")
+	
+	// Check for invalid characters
+	if strings.ContainsAny(tag, " \t\n\r") {
+		return fmt.Errorf("tag cannot contain whitespace")
+	}
+	
+	return nil
+}
+
+// validateTags validates a list of tags
+func validateTags(tags []string) error {
+	for _, tag := range tags {
+		if err := validateTagName(tag); err != nil {
+			return fmt.Errorf("invalid tag '%s': %w", tag, err)
+		}
+	}
+	return nil
+}
+
+// validateDueDate validates a due date string
+func validateDueDate(due string) error {
+	if due == "" {
+		return nil // Empty due date is valid
+	}
+	
+	// Try common formats
+	formats := []string{
+		"2006-01-02",
+		"2006-01-02T15:04:05",
+		"2006-01-02T15:04:05Z",
+		taskDateFormat,
+	}
+	
+	for _, format := range formats {
+		if _, err := time.Parse(format, due); err == nil {
+			return nil
+		}
+	}
+	
+	// Check for relative dates that taskwarrior understands
+	relatives := []string{"now", "today", "tomorrow", "yesterday", "monday", "tuesday", 
+		"wednesday", "thursday", "friday", "saturday", "sunday", "eod", "eow", "eom", "eoy"}
+	
+	due = strings.ToLower(due)
+	for _, rel := range relatives {
+		if due == rel || strings.HasPrefix(due, rel+"+") || strings.HasPrefix(due, rel+"-") {
+			return nil
+		}
+	}
+	
+	return fmt.Errorf("invalid due date format: %s", due)
+}
+
+// validatePriority validates a priority value
+func validatePriority(priority string) error {
+	switch priority {
+	case "", "H", "M", "L":
+		return nil
+	default:
+		return fmt.Errorf("invalid priority: %s (must be H, M, L, or empty)", priority)
+	}
+}
+
+// validateRecurrence validates a recurrence string
+func validateRecurrence(recur string) error {
+	if recur == "" {
+		return nil // Empty recurrence is valid
+	}
+	
+	// Basic validation - taskwarrior will do the full validation
+	if len(recur) < 2 {
+		return fmt.Errorf("recurrence too short")
+	}
+	
+	// Check for common patterns
+	validPrefixes := []string{"daily", "weekly", "monthly", "yearly", "biweekly", "bimonthly"}
+	for _, prefix := range validPrefixes {
+		if strings.HasPrefix(strings.ToLower(recur), prefix) {
+			return nil
+		}
+	}
+	
+	// Check for duration format (e.g., "3d", "2w", "1m")
+	if len(recur) >= 2 {
+		last := recur[len(recur)-1]
+		if (last == 'd' || last == 'w' || last == 'm' || last == 'y') && 
+			recur[:len(recur)-1] != "" {
+			return nil
+		}
+	}
+	
+	return nil // Let taskwarrior handle complex validation
+}
+
+// validateDescription validates a task description
+func validateDescription(desc string) error {
+	if strings.TrimSpace(desc) == "" {
+		return fmt.Errorf("description cannot be empty")
+	}
+	return nil
+}
\ No newline at end of file