Make the coverage report pretty

fuzzing/coverage/report_generation.go

@@ -22,6 +22,24 @@ var (
 func WriteHTMLReport(sourceAnalysis *SourceAnalysis, reportDir string) (string, error) {
 	// Define mappings onto some useful variables/functions.
 	functionMap := template.FuncMap{
+		"formatNumber": func(num uint) string {
+			// Format large numbers to be more readable (e.g., 1234 → 1.2K, 1500000 → 1.5M)
+			if num < 1000 {
+				return fmt.Sprintf("%d", num) // Keep small numbers as is
+			} else if num < 1000000 {
+				// Format as K (thousands)
+				value := float64(num) / 1000.0
+				return fmt.Sprintf("%.1fK", value)
+			} else if num < 1000000000 {
+				// Format as M (millions)
+				value := float64(num) / 1000000.0
+				return fmt.Sprintf("%.1fM", value)
+			} else {
+				// Format as B (billions)
+				value := float64(num) / 1000000000.0
+				return fmt.Sprintf("%.1fB", value)
+			}
+		},
 		"timeNow": time.Now,
 		"add": func(x int, y int) int {
 			return x + y
@@ -40,6 +58,18 @@ func WriteHTMLReport(sourceAnalysis *SourceAnalysis, reportDir string) (string,
 
 			return relativePath
 		},
+		"filePathToId": func(path string) string {
+			// Convert a file path to a safe HTML ID by replacing non-alphanumeric characters with underscores
+			safeId := ""
+			for _, c := range path {
+				if (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') || (c >= '0' && c <= '9') {
+					safeId += string(c)
+				} else {
+					safeId += "_"
+				}
+			}
+			return safeId
+		},
 		"percentageStr": func(x int, y int, decimals int) string {
 			// Determine our precision string
 			formatStr := "%." + strconv.Itoa(decimals) + "f"
@@ -56,6 +86,26 @@ func WriteHTMLReport(sourceAnalysis *SourceAnalysis, reportDir string) (string,
 			}
 			return int(math.Round(float64(x) / float64(y) * 100))
 		},
+		"getCoverageColor": func(percentage int) string {
+			// Color gradient: red (0%) -> yellow (50%) -> green (100%)
+			if percentage < 50 {
+				// Red to yellow (0-50%)
+				return fmt.Sprintf("hsl(%d, 90%%, 50%%)", int(float64(percentage)*1.2))
+			} else {
+				// Yellow to green (50-100%)
+				return fmt.Sprintf("hsl(%d, 90%%, 45%%)", 60+int(float64(percentage-50)*1.2))
+			}
+		},
+		"getCoverageColorAlpha": func(percentage int) string {
+			// Color gradient with alpha: red (0%) -> yellow (50%) -> green (100%)
+			if percentage < 50 {
+				// Red to yellow (0-50%)
+				return fmt.Sprintf("hsla(%d, 90%%, 50%%, 0.15)", int(float64(percentage)*1.2))
+			} else {
+				// Yellow to green (50-100%)
+				return fmt.Sprintf("hsla(%d, 90%%, 45%%, 0.15)", 60+int(float64(percentage-50)*1.2))
+			}
+		},
 	}
 
 	// Parse our HTML template