// Copyright (c) 2026 Zeni Kim <zenik@smarteching.com>
// Use of this source code is governed by MIT-style
// license that can be found in the LICENSE file.

package core

import (
	"embed"
	"strings"
	"testing"
	"time"
)

type templateFieldSample struct {
	Name string
	Age  int
}

func TestHasField(t *testing.T) {
	s := templateFieldSample{Name: "test", Age: 3}
	if !hasField(s, "Name") {
		t.Errorf("expected struct to have field 'Name'")
	}
	if !hasField(&s, "Age") {
		t.Errorf("expected pointer to struct to have field 'Age'")
	}
	if hasField(s, "Missing") {
		t.Errorf("expected struct NOT to have field 'Missing'")
	}
	if hasField(42, "Name") {
		t.Errorf("expected non-struct to have no fields")
	}
}

func TestCapitalize(t *testing.T) {
	tests := []struct {
		in   string
		want string
	}{
		{"hello world", "Hello world"},
		{"HELLO", "Hello"},
		{"", ""},
		{"a", "A"},
	}
	for _, tt := range tests {
		if got := capitalize(tt.in); got != tt.want {
			t.Errorf("capitalize(%q) = %q, want %q", tt.in, got, tt.want)
		}
	}
}

func TestPrepend(t *testing.T) {
	if got := prepend("World", "Hello, "); got != "Hello, World" {
		t.Errorf("prepend returned %q", got)
	}
}

func TestStrAppend(t *testing.T) {
	if got := strAppend("Hello", "!"); got != "Hello!" {
		t.Errorf("strAppend returned %q", got)
	}
}

func TestSplitHelper(t *testing.T) {
	got := split("a,b,c", ",")
	if len(got) != 3 {
		t.Fatalf("expected 3 parts, got %d", len(got))
	}
	if got[0] != "a" || got[2] != "c" {
		t.Errorf("unexpected split result: %v", got)
	}
}

func TestTruncate(t *testing.T) {
	if got := truncate(5, "hello world"); got != "hello…" {
		t.Errorf("truncate returned %q", got)
	}
	if got := truncate(20, "short"); got != "short" {
		t.Errorf("truncate should not modify short strings, got %q", got)
	}
	// Multibyte safety.
	if got := truncate(3, "héllo"); got != "hél…" {
		t.Errorf("truncate multibyte returned %q", got)
	}
}

func TestFmtNumber(t *testing.T) {
	if got := fmtNumber(1000000); got != "1,000,000" {
		t.Errorf("fmtNumber(int) = %q, want %q", got, "1,000,000")
	}
	if got := fmtNumber(int64(1500)); got != "1,500" {
		t.Errorf("fmtNumber(int64) = %q, want %q", got, "1,500")
	}
	if got := fmtNumber(12.5); got != "12.50" {
		t.Errorf("fmtNumber(float64) = %q, want %q", got, "12.50")
	}
	// Fallback for unsupported types.
	if got := fmtNumber("abc"); got != "abc" {
		t.Errorf("fmtNumber(string) = %q, want %q", got, "abc")
	}
}

func TestFmtDate(t *testing.T) {
	d := time.Date(2023, time.May, 2, 15, 4, 0, 0, time.UTC)
	if got := fmtDate(d, "short"); got != "02 May 2023" {
		t.Errorf("fmtDate(short) = %q", got)
	}
	if got := fmtDate(d, "long"); got != "02 May 2023" {
		t.Errorf("fmtDate(long) = %q", got)
	}
	if got := fmtDate(d, "iso"); got != "2023-05-02" {
		t.Errorf("fmtDate(iso) = %q", got)
	}
	if got := fmtDate(d, "datetime"); got != "02 May 2023 15:04" {
		t.Errorf("fmtDate(datetime) = %q", got)
	}
	if got := fmtDate(d, "02/01/2006"); got != "02/05/2023" {
		t.Errorf("fmtDate(custom) = %q", got)
	}
}

func TestTimeAgo(t *testing.T) {
	tests := []struct {
		name string
		at   time.Time
		want string
	}{
		{"just now", time.Now().Add(-10 * time.Second), "just now"},
		{"minutes", time.Now().Add(-5 * time.Minute), "5 minutes ago"},
		{"one minute", time.Now().Add(-1 * time.Minute), "1 minute ago"},
		{"hours", time.Now().Add(-3 * time.Hour), "3 hours ago"},
		{"one hour", time.Now().Add(-1 * time.Hour), "1 hour ago"},
		{"days", time.Now().Add(-48 * time.Hour), "2 days ago"},
		{"one day", time.Now().Add(-24 * time.Hour), "1 day ago"},
	}
	for _, tt := range tests {
		if got := timeAgo(tt.at); got != tt.want {
			t.Errorf("timeAgo(%s) = %q, want %q", tt.name, got, tt.want)
		}
	}
}

func TestPlural(t *testing.T) {
	if got := plural(1, "item"); got != "1 item" {
		t.Errorf("plural(1) = %q", got)
	}
	if got := plural(3, "item"); got != "3 items" {
		t.Errorf("plural(3) = %q", got)
	}
}

func TestFirstAndLast(t *testing.T) {
	items := []int{10, 20, 30}
	if got := first(items); got != 10 {
		t.Errorf("first = %v, want 10", got)
	}
	if got := last(items); got != 30 {
		t.Errorf("last = %v, want 30", got)
	}
	if got := first([]int{}); got != nil {
		t.Errorf("first of empty slice should be nil, got %v", got)
	}
	if got := last([]int{}); got != nil {
		t.Errorf("last of empty slice should be nil, got %v", got)
	}
	if got := first("not a slice"); got != nil {
		t.Errorf("first of non-slice should be nil, got %v", got)
	}
}

func TestSliceOf(t *testing.T) {
	items := []int{1, 2, 3, 4, 5}
	got, ok := sliceOf(items, 1, 4).([]int)
	if !ok {
		t.Fatalf("sliceOf should return a slice")
	}
	if len(got) != 3 || got[0] != 2 || got[2] != 4 {
		t.Errorf("sliceOf returned %v", got)
	}
	// Negative start should be clamped to 0.
	got, _ = sliceOf(items, -5, 2).([]int)
	if len(got) != 2 || got[0] != 1 {
		t.Errorf("sliceOf with negative start returned %v", got)
	}
	// End beyond length should be clamped.
	got, _ = sliceOf(items, 3, 100).([]int)
	if len(got) != 2 || got[1] != 5 {
		t.Errorf("sliceOf with large end returned %v", got)
	}
	if got := sliceOf("not slice", 0, 1); got != nil {
		t.Errorf("sliceOf of non-slice should be nil, got %v", got)
	}
}

func TestContainsHelper(t *testing.T) {
	if !contains("hello world", "world") {
		t.Errorf("expected substring match")
	}
	if contains("hello", "xyz") {
		t.Errorf("expected no substring match")
	}
	items := []string{"a", "b", "c"}
	if !contains(items, "b") {
		t.Errorf("expected element in slice")
	}
	if contains(items, "z") {
		t.Errorf("expected element not in slice")
	}
	if contains(42, "x") {
		t.Errorf("expected no match for non-string/non-slice")
	}
}

func TestJoinHelper(t *testing.T) {
	if got := join([]string{"a", "b", "c"}, ", "); got != "a, b, c" {
		t.Errorf("join returned %q", got)
	}
}

func TestDefaultVal(t *testing.T) {
	if got := defaultVal("N/A", ""); got != "N/A" {
		t.Errorf("defaultVal for empty string = %v, want N/A", got)
	}
	if got := defaultVal("N/A", nil); got != "N/A" {
		t.Errorf("defaultVal for nil = %v, want N/A", got)
	}
	if got := defaultVal("N/A", 0); got != "N/A" {
		t.Errorf("defaultVal for zero = %v, want N/A", got)
	}
	if got := defaultVal("N/A", "value"); got != "value" {
		t.Errorf("defaultVal for present value = %v, want value", got)
	}
}

func TestTernary(t *testing.T) {
	if got := ternary("yes", "no", true); got != "yes" {
		t.Errorf("ternary(true) = %v", got)
	}
	if got := ternary("yes", "no", false); got != "no" {
		t.Errorf("ternary(false) = %v", got)
	}
}

func TestCoalesce(t *testing.T) {
	if got := coalesce(nil, "", "first", "second"); got != "first" {
		t.Errorf("coalesce = %v, want first", got)
	}
	if got := coalesce(nil, ""); got != nil {
		t.Errorf("coalesce of all empty should be nil, got %v", got)
	}
}

func TestFuncMap(t *testing.T) {
	fm := funcMap()
	expected := []string{
		"hasField", "capitalize", "prepend", "strAppend", "split", "truncate",
		"fmtNumber", "fmtDate", "timeAgo", "first", "last", "sliceOf",
		"contains", "join", "defaultVal", "ternary", "coalesce",
	}
	for _, name := range expected {
		if _, ok := fm[name]; !ok {
			t.Errorf("expected funcMap to contain %q", name)
		}
	}
}

//go:embed all:testingdata/templates
var testTemplatesFS embed.FS

func TestNewTemplatesAndRenderNamed(t *testing.T) {
	// Register the built-in components plus our test templates.
	NewTemplates(components_resources, testTemplatesFS)
	if tmpl == nil {
		t.Fatalf("expected templates to be initialized")
	}

	out, err := RenderNamedTemplate("test_greeting", map[string]interface{}{"Name": "Goffee"})
	if err != nil {
		t.Fatalf("failed rendering named template: %v", err)
	}
	if !strings.Contains(string(out), "Hello, Goffee!") {
		t.Errorf("unexpected rendered output: %q", string(out))
	}
}

func TestRenderNamedTemplateMissing(t *testing.T) {
	NewTemplates(components_resources, testTemplatesFS)
	_, err := RenderNamedTemplate("does_not_exist", nil)
	if err == nil {
		t.Errorf("expected error rendering a missing template")
	}
}

func TestRenderNamedTemplateUsesFuncMap(t *testing.T) {
	NewTemplates(components_resources, testTemplatesFS)
	out, err := RenderNamedTemplate("test_funcmap", map[string]interface{}{"Raw": "hello world"})
	if err != nil {
		t.Fatalf("failed rendering named template: %v", err)
	}
	if !strings.Contains(string(out), "Hello world") {
		t.Errorf("expected capitalize helper to be applied, got %q", string(out))
	}
}