package automc

import (
	"sort"
	"testing"
)

func TestDiff(t *testing.T) {
	cases := []struct {
		name        string
		prev, next  map[string]route
		wantAddHost []string
		wantDel     []string
	}{
		{
			name:        "empty to empty",
			prev:        map[string]route{},
			next:        map[string]route{},
			wantAddHost: nil,
			wantDel:     nil,
		},
		{
			name:        "add one",
			prev:        map[string]route{},
			next:        map[string]route{"a.example.com": {name: "a", domain: "a.example.com", address: "10.0.0.1:25565"}},
			wantAddHost: []string{"a.example.com"},
			wantDel:     nil,
		},
		{
			name:        "delete one",
			prev:        map[string]route{"a.example.com": {name: "a", domain: "a.example.com", address: "10.0.0.1:25565"}},
			next:        map[string]route{},
			wantAddHost: nil,
			wantDel:     []string{"a.example.com"},
		},
		{
			name: "address change",
			prev: map[string]route{"a.example.com": {name: "a", domain: "a.example.com", address: "10.0.0.1:25565"}},
			next: map[string]route{"a.example.com": {name: "a", domain: "a.example.com", address: "10.0.0.2:25565"}},
			wantAddHost: []string{"a.example.com"},
			wantDel:     nil,
		},
		{
			name: "name change with same address triggers re-register (waker rebind)",
			prev: map[string]route{"a.example.com": {name: "a", domain: "a.example.com", address: "10.0.0.1:25565"}},
			next: map[string]route{"a.example.com": {name: "b", domain: "a.example.com", address: "10.0.0.1:25565"}},
			wantAddHost: []string{"a.example.com"},
			wantDel:     nil,
		},
		{
			name: "no change",
			prev: map[string]route{"a.example.com": {name: "a", domain: "a.example.com", address: "10.0.0.1:25565"}},
			next: map[string]route{"a.example.com": {name: "a", domain: "a.example.com", address: "10.0.0.1:25565"}},
			wantAddHost: nil,
			wantDel:     nil,
		},
		{
			name: "mixed add + delete",
			prev: map[string]route{
				"a.example.com": {name: "a", domain: "a.example.com", address: "10.0.0.1:25565"},
				"b.example.com": {name: "b", domain: "b.example.com", address: "10.0.0.2:25565"},
			},
			next: map[string]route{
				"a.example.com": {name: "a", domain: "a.example.com", address: "10.0.0.1:25565"},
				"c.example.com": {name: "c", domain: "c.example.com", address: "10.0.0.3:25565"},
			},
			wantAddHost: []string{"c.example.com"},
			wantDel:     []string{"b.example.com"},
		},
	}

	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			add, del := diff(tc.prev, tc.next)
			gotAdd := make([]string, 0, len(add))
			for _, r := range add {
				gotAdd = append(gotAdd, r.domain)
			}
			sort.Strings(gotAdd)
			sort.Strings(del)
			sort.Strings(tc.wantAddHost)
			sort.Strings(tc.wantDel)
			if !equalSlice(gotAdd, tc.wantAddHost) {
				t.Errorf("add: got %v want %v", gotAdd, tc.wantAddHost)
			}
			if !equalSlice(del, tc.wantDel) {
				t.Errorf("del: got %v want %v", del, tc.wantDel)
			}
		})
	}
}

func equalSlice(a, b []string) bool {
	if len(a) != len(b) {
		return false
	}
	for i := range a {
		if a[i] != b[i] {
			return false
		}
	}
	return true
}