package traverse

import (
	"fmt"
	"net"
	"strings"
	"sync"
	"testing"

	"github.com/miekg/dns"
)

func TestNewInfoCache(t *testing.T) {
	c := NewInfoCache(nil)
	if c.parent != nil {
		t.Error("root cache should have nil parent")
	}
	if c.NSCount() != 0 {
		t.Errorf("NSCount = %d, want 0", c.NSCount())
	}
	if c.GlueCount() != 0 {
		t.Errorf("GlueCount = %d, want 0", c.GlueCount())
	}
}

func TestInfoCacheStoreAndLookupNS(t *testing.T) {
	c := NewInfoCache(nil)

	c.StoreNS("com.", []string{"a.gtld-servers.net.", "b.gtld-servers.net."})
	if c.NSCount() != 1 {
		t.Errorf("NSCount = %d, want 1", c.NSCount())
	}

	names := c.LookupNS("com.")
	if len(names) != 2 {
		t.Fatalf("expected 2 nameservers, got %d", len(names))
	}
	if names[0] != "a.gtld-servers.net." {
		t.Errorf("nameserver[0] = %q, want %q", names[0], "a.gtld-servers.net.")
	}
}

func TestInfoCacheNSDedup(t *testing.T) {
	c := NewInfoCache(nil)
	c.StoreNS("com.", []string{"a.gtld-servers.net.", "a.gtld-servers.net."})
	names := c.LookupNS("com.")
	if len(names) != 1 {
		t.Errorf("expected 1 deduped NS, got %d", len(names))
	}
}

func TestInfoCacheNSCaseInsensitive(t *testing.T) {
	c := NewInfoCache(nil)
	c.StoreNS("COM.", []string{"A.GTLD-SERVERS.NET."})
	names := c.LookupNS("com.")
	if len(names) != 1 {
		t.Fatalf("expected 1 NS, got %d", len(names))
	}
	if names[0] != "a.gtld-servers.net." {
		t.Errorf("NS = %q, want %q", names[0], "a.gtld-servers.net.")
	}
}

func TestInfoCacheNSLookupMiss(t *testing.T) {
	c := NewInfoCache(nil)
	names := c.LookupNS("org.")
	if names != nil {
		t.Errorf("expected nil for miss, got %v", names)
	}
}

func TestInfoCacheNSStoreEmpty(t *testing.T) {
	c := NewInfoCache(nil)
	c.StoreNS("com.", nil)
	if c.NSCount() != 0 {
		t.Errorf("expected 0 after empty store, got %d", c.NSCount())
	}
}

func TestInfoCacheChainedNS(t *testing.T) {
	parent := NewInfoCache(nil)
	parent.StoreNS("com.", []string{"a.gtld-servers.net."})

	child := parent.Child()
	if child.parent != parent {
		t.Error("child parent should be the parent cache")
	}

	names := child.LookupNS("com.")
	if len(names) != 1 {
		t.Fatalf("expected 1 NS from parent, got %d", len(names))
	}
	if child.NSCount() != 0 {
		t.Errorf("child NSCount = %d, want 0", child.NSCount())
	}
}

func TestInfoCacheChildOverridesParent(t *testing.T) {
	parent := NewInfoCache(nil)
	parent.StoreNS("com.", []string{"a.gtld-servers.net."})

	child := parent.Child()
	child.StoreNS("com.", []string{"b.gtld-servers.net."})

	names := child.LookupNS("com.")
	if len(names) != 1 {
		t.Fatalf("expected 1 NS, got %d", len(names))
	}
	if names[0] != "b.gtld-servers.net." {
		t.Errorf("expected child's NS to override, got %q", names[0])
	}
}

func TestInfoCacheStoreAndLookupGlue(t *testing.T) {
	c := NewInfoCache(nil)
	addrs := []net.IP{net.ParseIP("1.2.3.4"), net.ParseIP("5.6.7.8")}
	c.StoreGlue("ns1.example.com.", addrs)

	result := c.LookupGlue("ns1.example.com.")
	if len(result) != 2 {
		t.Fatalf("expected 2 glue addresses, got %d", len(result))
	}
}

func TestInfoCacheGlueDedup(t *testing.T) {
	c := NewInfoCache(nil)
	ip := net.ParseIP("1.2.3.4")
	c.StoreGlue("ns1.example.com.", []net.IP{ip, ip})
	result := c.LookupGlue("ns1.example.com.")
	if len(result) != 1 {
		t.Errorf("expected 1 deduped glue, got %d", len(result))
	}
}

func TestInfoCacheChainedGlue(t *testing.T) {
	parent := NewInfoCache(nil)
	parent.StoreGlue("ns1.example.com.", []net.IP{net.ParseIP("1.2.3.4")})

	child := parent.Child()
	result := child.LookupGlue("ns1.example.com.")
	if len(result) != 1 {
		t.Fatalf("expected 1 glue from parent, got %d", len(result))
	}
	if child.GlueCount() != 0 {
		t.Errorf("child GlueCount = %d, want 0", child.GlueCount())
	}
}

func TestInfoCacheGlueLookupMiss(t *testing.T) {
	c := NewInfoCache(nil)
	result := c.LookupGlue("nonexistent.example.com.")
	if result != nil {
		t.Errorf("expected nil for miss, got %v", result)
	}
}

func TestInfoCacheConcurrentAccess(t *testing.T) {
	c := NewInfoCache(nil)
	var wg sync.WaitGroup

	for i := 0; i < 100; i++ {
		wg.Add(1)
		go func(i int) {
			defer wg.Done()
			name := strings.ToLower(dns.Fqdn(fmt.Sprintf("ns%d.example.com.", i)))
			c.StoreNS("example.com.", []string{name})
			c.StoreGlue(name, []net.IP{net.ParseIP(fmt.Sprintf("1.2.3.%d", i%256))})
			_ = c.LookupNS("example.com.")
			_ = c.LookupGlue(name)
		}(i)
	}
	wg.Wait()
}

func TestInfoCacheNilParent(t *testing.T) {
	c := NewInfoCache(nil)
	if c.LookupNS("com.") != nil {
		t.Error("root cache should return nil for miss")
	}
	if c.LookupGlue("ns.example.com.") != nil {
		t.Error("root cache should return nil for glue miss")
	}
}

func TestNormalize(t *testing.T) {
	tests := []struct {
		input string
		want  string
	}{
		{"example.com", "example.com."},
		{"Example.COM.", "example.com."},
		{"EXAMPLE.COM", "example.com."},
	}

	for _, tt := range tests {
		t.Run(tt.input, func(t *testing.T) {
			got := normalize(tt.input)
			if got != tt.want {
				t.Errorf("normalize(%q) = %q, want %q", tt.input, got, tt.want)
			}
		})
	}
}