feat: add filter on price range

WIP

Signed-off-by: Julien Riou <julien@riou.xyz>

filter_range.go

@@ -0,0 +1,48 @@
+package main
+
+import (
+	"regexp"
+
+	log "github.com/sirupsen/logrus"
+)
+
+// RangeFilter to store the pattern to match product model and price limits
+type RangeFilter struct {
+	model *regexp.Regexp
+	min   float64
+	max   float64
+}
+
+// NewRangeFilter to create a RangeFilter
+func NewRangeFilter(regex string, min float64, max float64) (*RangeFilter, error) {
+	var err error
+	var compiledRegex *regexp.Regexp
+
+	log.Debugf("compiling model filter regex")
+	if regex != "" {
+		compiledRegex, err = regexp.Compile(regex)
+		if err != nil {
+			return nil, err
+		}
+	}
+
+	return &RangeFilter{
+		model: compiledRegex,
+		min:   min,
+		max:   max,
+	}, nil
+}
+
+// Include returns false when a product name matches the model regex and price is outside of the range
+// implements the Filter interface
+func (f *RangeFilter) Include(product *Product) bool {
+	if f.model == nil {
+		return true
+	}
+	if f.model.MatchString(product.Name) && product.Price < f.min || product.Price > f.max {
+		log.Debugf("product %s excluded because price for the model is outside of the range [%.2f-%.2f]", product.Name, f.min, f.max)
+		return false
+	}
+	log.Debugf("product %s included because price range filter is not applicable", product.Name)
+	return true
+}

filter_range_test.go

@@ -0,0 +1,45 @@
+package main
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestRangeFilter(t *testing.T) {
+	tests := []struct {
+		name     string  // product name
+		price    float64 // product price
+		model    string  // model regex to apply on the product name
+		min      float64 // minimum price
+		max      float64 // maximum price
+		included bool    // should be included or not
+	}{
+		{"MSI GeForce RTX 3090 GAMING X", 99.99, "3090", 50.0, 100.0, true},   // model match and price is in the range, should be included
+		{"MSI GeForce RTX 3090 GAMING X", 99.99, "3080", 50.0, 100.0, true},   // model doesn't match, should be included
+		{"MSI GeForce RTX 3090 GAMING X", 999.99, "3090", 50.0, 100.0, false}, // model match and price is outside of the range, shoud not be included
+		{"MSI GeForce RTX 3090 GAMING X", 99.99, "", 50.0, 100.0, true},       // model regex is missing, should be included
+	}
+
+	for i, tc := range tests {
+		t.Run(fmt.Sprintf("TestRangeFilter#%d", i), func(t *testing.T) {
+			product := &Product{Name: tc.name, Price: tc.price}
+			filter, err := NewRangeFilter(tc.model, tc.min, tc.max)
+			if err != nil {
+				t.Errorf("cannot create filter with model regex '%s' and price range [%.2f, %.2f]: %s", tc.model, tc.min, tc.max, err)
+			}
+
+			included := filter.Include(product)
+
+			if included != tc.included {
+				t.Errorf("product '%s' with model regex '%s' and range [%.2f, %.2f]: got included=%t, want included=%t", tc.name, tc.model, tc.min, tc.max, included, tc.included)
+			} else {
+				if included {
+					t.Logf("product '%s' included by model regex '%s' and range [%.2f, %.2f]", tc.name, tc.model, tc.min, tc.max)
+				} else {
+					t.Logf("product '%s' excluded by model regex '%s' and range [%.2f, %.2f]", tc.name, tc.model, tc.min, tc.max)
+				}
+			}
+
+		})
+	}
+}