Add terminal display layer with lipgloss styling and JSON output

Rendering layer for deals, stores, and categories with two output
modes: styled terminal text using lipgloss (color-coded BOGO tags,
price highlights, dim metadata, word-wrapped descriptions) and
compact JSON for programmatic consumption.

JSON output types (DealJSON, StoreJSON) normalize raw API fields —
cleaning HTML entities, dereferencing nullable pointers, and
computing derived fields like isBogo. Terminal output includes
contextual headers with item counts and date ranges. Tests verify
both rendering modes including HTML entity handling and nil safety.

internal/display/formatter_test.go

@@ -0,0 +1,152 @@
+package display_test
+
+import (
+	"bytes"
+	"encoding/json"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+	"github.com/tayloree/publix-deals/internal/api"
+	"github.com/tayloree/publix-deals/internal/display"
+)
+
+func ptr(s string) *string { return &s }
+
+func sampleDeals() []api.SavingItem {
+	return []api.SavingItem{
+		{
+			ID:                 "1",
+			Title:              ptr("Chicken Breasts"),
+			Savings:            ptr("$3.99 lb"),
+			Description:        ptr("USDA Grade A, 97% Fat Free"),
+			Department:         ptr("Meat"),
+			Brand:              ptr("Publix"),
+			Categories:         []string{"meat"},
+			AdditionalDealInfo: ptr("SAVE UP TO $1.00 LB"),
+			StartFormatted:     "2/18",
+			EndFormatted:       "2/24",
+		},
+		{
+			ID:             "2",
+			Title:          ptr("Nutella & More"),
+			Savings:        ptr("Buy 1 Get 1 FREE"),
+			Department:     ptr("Grocery"),
+			Categories:     []string{"bogo", "grocery"},
+			StartFormatted: "2/18",
+			EndFormatted:   "2/24",
+		},
+	}
+}
+
+func TestPrintDeals_ContainsExpectedContent(t *testing.T) {
+	var buf bytes.Buffer
+	display.PrintDeals(&buf, sampleDeals())
+	output := buf.String()
+
+	assert.Contains(t, output, "Publix Weekly Deals")
+	assert.Contains(t, output, "2 items")
+	assert.Contains(t, output, "Chicken Breasts")
+	assert.Contains(t, output, "$3.99 lb")
+	assert.Contains(t, output, "SAVE UP TO $1.00 LB")
+	assert.Contains(t, output, "BOGO") // Nutella is bogo
+	// HTML entities should be unescaped
+	assert.Contains(t, output, "Nutella & More")
+	assert.NotContains(t, output, "&")
+}
+
+func TestPrintDealsJSON(t *testing.T) {
+	var buf bytes.Buffer
+	err := display.PrintDealsJSON(&buf, sampleDeals())
+	require.NoError(t, err)
+	assert.NotContains(t, buf.String(), "\n  ")
+
+	var deals []display.DealJSON
+	err = json.Unmarshal(buf.Bytes(), &deals)
+	require.NoError(t, err)
+
+	assert.Len(t, deals, 2)
+	assert.Equal(t, "Chicken Breasts", deals[0].Title)
+	assert.Equal(t, "$3.99 lb", deals[0].Savings)
+	assert.Equal(t, "Meat", deals[0].Department)
+	assert.False(t, deals[0].IsBogo)
+
+	// HTML entities should be clean in JSON too
+	assert.Equal(t, "Nutella & More", deals[1].Title)
+	assert.True(t, deals[1].IsBogo)
+}
+
+func TestPrintDealsJSON_NilFields(t *testing.T) {
+	items := []api.SavingItem{{ID: "nil-test"}}
+	var buf bytes.Buffer
+	err := display.PrintDealsJSON(&buf, items)
+	require.NoError(t, err)
+
+	var deals []display.DealJSON
+	err = json.Unmarshal(buf.Bytes(), &deals)
+	require.NoError(t, err)
+	assert.Len(t, deals, 1)
+	assert.Equal(t, "", deals[0].Title)
+	assert.NotNil(t, deals[0].Categories)
+}
+
+func TestPrintStores(t *testing.T) {
+	stores := []api.Store{
+		{Key: "01425", Name: "Peachers Mill", Addr: "1490 Tiny Town Rd", City: "Clarksville", State: "TN", Zip: "37042", Distance: "5"},
+	}
+	var buf bytes.Buffer
+	display.PrintStores(&buf, stores, "37042")
+	output := buf.String()
+
+	assert.Contains(t, output, "37042")
+	assert.Contains(t, output, "#1425")
+	assert.Contains(t, output, "Peachers Mill")
+	assert.Contains(t, output, "5 miles")
+}
+
+func TestPrintStoresJSON(t *testing.T) {
+	stores := []api.Store{
+		{Key: "01425", Name: "Peachers Mill", Addr: "1490 Tiny Town Rd", City: "Clarksville", State: "TN", Zip: "37042", Distance: "5"},
+	}
+	var buf bytes.Buffer
+	err := display.PrintStoresJSON(&buf, stores)
+	require.NoError(t, err)
+	assert.NotContains(t, buf.String(), "\n  ")
+
+	var out []display.StoreJSON
+	err = json.Unmarshal(buf.Bytes(), &out)
+	require.NoError(t, err)
+
+	assert.Len(t, out, 1)
+	assert.Equal(t, "1425", out[0].Number)
+	assert.Equal(t, "Peachers Mill", out[0].Name)
+	assert.Contains(t, out[0].Address, "Clarksville")
+}
+
+func TestPrintCategories(t *testing.T) {
+	cats := map[string]int{"bogo": 10, "meat": 5, "produce": 3}
+	var buf bytes.Buffer
+	display.PrintCategories(&buf, cats, "1425")
+	output := buf.String()
+
+	assert.Contains(t, output, "1425")
+	assert.Contains(t, output, "bogo")
+	assert.Contains(t, output, "10 deals")
+	assert.Contains(t, output, "meat")
+	assert.Contains(t, output, "produce")
+}
+
+func TestPrintCategoriesJSON(t *testing.T) {
+	cats := map[string]int{"bogo": 10, "meat": 5}
+	var buf bytes.Buffer
+	err := display.PrintCategoriesJSON(&buf, cats)
+	require.NoError(t, err)
+	assert.NotContains(t, buf.String(), "\n  ")
+
+	var out map[string]int
+	err = json.Unmarshal(buf.Bytes(), &out)
+	require.NoError(t, err)
+
+	assert.Equal(t, 10, out["bogo"])
+	assert.Equal(t, 5, out["meat"])
+}