package cache

import (
	"encoding/json"
	"os"
	"path/filepath"
	"testing"
	"time"
)

func TestNew(t *testing.T) {
	c := New("/tmp/test.json", 60)
	if c == nil {
		t.Fatal("New returned nil")
	}
	if c.ttl != 60*time.Second {
		t.Errorf("ttl: got %v, want %v", c.ttl, 60*time.Second)
	}
}

func TestLoad_MissingFile(t *testing.T) {
	c := New("/nonexistent/path/cache.json", 60)
	if err := c.Load(); err != nil {
		t.Errorf("Load on missing file should not error, got: %v", err)
	}
}

func TestLoad_InvalidJSON(t *testing.T) {
	f := tempFile(t, []byte("not json"))
	c := New(f, 60)
	if err := c.Load(); err == nil {
		t.Error("Load on invalid JSON should return an error")
	}
}

func TestSaveAndLoad_Roundtrip(t *testing.T) {
	path := filepath.Join(t.TempDir(), "cache.json")
	c := New(path, 3600)

	c.Upsert(Entry{Name: "host-a", IP: "10.0.0.1", Kind: "device"})
	c.Upsert(Entry{Name: "host-b", IP: "10.0.0.2", Kind: "vm", Tags: []string{"prod"}})

	if err := c.Save(); err != nil {
		t.Fatalf("Save: %v", err)
	}

	c2 := New(path, 3600)
	if err := c2.Load(); err != nil {
		t.Fatalf("Load: %v", err)
	}

	e, _ := c2.Get("host-a")
	if e.IP != "10.0.0.1" {
		t.Errorf("host-a IP: got %q, want %q", e.IP, "10.0.0.1")
	}
	e2, _ := c2.Get("host-b")
	if len(e2.Tags) != 1 || e2.Tags[0] != "prod" {
		t.Errorf("host-b tags: got %v, want [prod]", e2.Tags)
	}
}

func TestSave_CreatesDirectory(t *testing.T) {
	dir := t.TempDir()
	path := filepath.Join(dir, "sub", "dir", "cache.json")
	c := New(path, 60)
	c.Upsert(Entry{Name: "x", IP: "1.2.3.4", Kind: "device"})
	if err := c.Save(); err != nil {
		t.Fatalf("Save: %v", err)
	}
	if _, err := os.Stat(path); err != nil {
		t.Errorf("cache file not created: %v", err)
	}
}

func TestUpsert_SetsTimestamp(t *testing.T) {
	c := New("", 60)
	before := time.Now()
	c.Upsert(Entry{Name: "h", IP: "1.1.1.1", Kind: "device"})
	e, _ := c.Get("h")
	if e.CachedAt.Before(before) {
		t.Error("CachedAt should be set to current time on Upsert")
	}
}

func TestUpsert_Overwrites(t *testing.T) {
	c := New("", 60)
	c.Upsert(Entry{Name: "host", IP: "10.0.0.1", Kind: "device"})
	c.Upsert(Entry{Name: "host", IP: "10.0.0.2", Kind: "device"})
	e, _ := c.Get("host")
	if e.IP != "10.0.0.2" {
		t.Errorf("Upsert should overwrite: got %q, want %q", e.IP, "10.0.0.2")
	}
}

func TestSearch_PrefixMatch(t *testing.T) {
	c := New("", 60)
	c.Upsert(Entry{Name: "app-server-01", IP: "10.0.0.1", Kind: "device"})
	c.Upsert(Entry{Name: "app-server-02", IP: "10.0.0.2", Kind: "vm"})
	c.Upsert(Entry{Name: "db-server-01", IP: "10.0.0.3", Kind: "device"})

	results := c.Search("app")
	if len(results) != 2 {
		t.Errorf("Search(app): got %d results, want 2", len(results))
	}
}

func TestSearch_CaseInsensitive(t *testing.T) {
	c := New("", 60)
	c.Upsert(Entry{Name: "App-Server", IP: "10.0.0.1", Kind: "device"})

	if len(c.Search("app")) != 1 {
		t.Error("Search should be case-insensitive")
	}
	if len(c.Search("APP")) != 1 {
		t.Error("Search should be case-insensitive for uppercase")
	}
}

func TestSearch_EmptyPrefix(t *testing.T) {
	c := New("", 60)
	c.Upsert(Entry{Name: "a", IP: "1.1.1.1", Kind: "device"})
	c.Upsert(Entry{Name: "b", IP: "2.2.2.2", Kind: "vm"})

	if len(c.Search("")) != 2 {
		t.Error("Search('') should return all entries")
	}
}

func TestSearch_NoMatch(t *testing.T) {
	c := New("", 60)
	c.Upsert(Entry{Name: "host", IP: "1.1.1.1", Kind: "device"})

	if len(c.Search("xyz")) != 0 {
		t.Error("Search should return empty slice when no match")
	}
}

func TestGet_Fresh(t *testing.T) {
	c := New("", 3600)
	c.Upsert(Entry{Name: "host", IP: "10.0.0.1", Kind: "device"})

	e, fresh := c.Get("host")
	if !fresh {
		t.Error("entry just inserted should be fresh")
	}
	if e.IP != "10.0.0.1" {
		t.Errorf("IP: got %q, want %q", e.IP, "10.0.0.1")
	}
}

func TestGet_Expired(t *testing.T) {
	c := New("", 1) // 1 second TTL
	e := Entry{Name: "host", IP: "10.0.0.1", Kind: "device", CachedAt: time.Now().Add(-2 * time.Second)}
	c.mu.Lock()
	c.entries["host"] = e
	c.mu.Unlock()

	_, fresh := c.Get("host")
	if fresh {
		t.Error("entry older than TTL should not be fresh")
	}
}

func TestGet_ZeroTTL_AlwaysStale(t *testing.T) {
	c := New("", 0) // TTL=0 means never fresh for connect mode
	c.Upsert(Entry{Name: "host", IP: "10.0.0.1", Kind: "device"})

	_, fresh := c.Get("host")
	if fresh {
		t.Error("TTL=0 should always return fresh=false")
	}
}

func TestGet_Missing(t *testing.T) {
	c := New("", 60)
	_, fresh := c.Get("nonexistent")
	if fresh {
		t.Error("missing entry should not be fresh")
	}
}

func TestClear(t *testing.T) {
	c := New("", 60)
	c.Upsert(Entry{Name: "a", IP: "1.1.1.1", Kind: "device"})
	c.Upsert(Entry{Name: "b", IP: "2.2.2.2", Kind: "vm"})
	c.Clear()

	if len(c.All()) != 0 {
		t.Error("Clear should remove all entries")
	}
}

func TestAll(t *testing.T) {
	c := New("", 60)
	c.Upsert(Entry{Name: "a", IP: "1.1.1.1", Kind: "device"})
	c.Upsert(Entry{Name: "b", IP: "2.2.2.2", Kind: "vm"})

	all := c.All()
	if len(all) != 2 {
		t.Errorf("All: got %d entries, want 2", len(all))
	}
}

func TestSave_ProducesValidJSON(t *testing.T) {
	path := filepath.Join(t.TempDir(), "cache.json")
	c := New(path, 60)
	c.Upsert(Entry{Name: "host", IP: "10.0.0.1", Kind: "device", Tags: []string{"mgmt"}})

	if err := c.Save(); err != nil {
		t.Fatalf("Save: %v", err)
	}

	data, _ := os.ReadFile(path)
	var df diskFormat
	if err := json.Unmarshal(data, &df); err != nil {
		t.Fatalf("saved file is not valid JSON: %v", err)
	}
	if len(df.Entries) != 1 {
		t.Errorf("expected 1 entry in JSON, got %d", len(df.Entries))
	}
}

func TestMarkUsed_SetsLastUsed(t *testing.T) {
	c := New("", 60)
	c.Upsert(Entry{Name: "host", IP: "10.0.0.1", Kind: "device"})

	before := time.Now()
	c.MarkUsed("host")

	e, _ := c.Get("host")
	if e.LastUsed.Before(before) {
		t.Error("LastUsed should be set to current time by MarkUsed")
	}
}

func TestMarkUsed_NoopForMissingEntry(t *testing.T) {
	c := New("", 60)
	c.MarkUsed("nonexistent") // should not panic
}

func TestRecentlyUsed_ReturnsTopN(t *testing.T) {
	c := New("", 60)
	c.Upsert(Entry{Name: "a", IP: "1.1.1.1", Kind: "device"})
	c.Upsert(Entry{Name: "b", IP: "2.2.2.2", Kind: "device"})
	c.Upsert(Entry{Name: "c", IP: "3.3.3.3", Kind: "device"})

	c.MarkUsed("c")
	time.Sleep(time.Millisecond)
	c.MarkUsed("a")

	results := c.RecentlyUsed(2)
	if len(results) != 2 {
		t.Fatalf("RecentlyUsed(2): got %d results, want 2", len(results))
	}
	if results[0].Name != "a" {
		t.Errorf("first result: got %q, want %q", results[0].Name, "a")
	}
	if results[1].Name != "c" {
		t.Errorf("second result: got %q, want %q", results[1].Name, "c")
	}
}

func TestRecentlyUsed_ExcludesNeverUsed(t *testing.T) {
	c := New("", 60)
	c.Upsert(Entry{Name: "used", IP: "1.1.1.1", Kind: "device"})
	c.Upsert(Entry{Name: "unused", IP: "2.2.2.2", Kind: "device"})
	c.MarkUsed("used")

	results := c.RecentlyUsed(10)
	if len(results) != 1 || results[0].Name != "used" {
		t.Errorf("RecentlyUsed should exclude entries with zero LastUsed, got %v", results)
	}
}

func TestRecentlyUsed_EmptyCache(t *testing.T) {
	c := New("", 60)
	if results := c.RecentlyUsed(10); len(results) != 0 {
		t.Errorf("RecentlyUsed on empty cache: got %d, want 0", len(results))
	}
}

func TestMarkUsed_RoundtripViaSave(t *testing.T) {
	path := filepath.Join(t.TempDir(), "cache.json")
	c := New(path, 3600)
	c.Upsert(Entry{Name: "host", IP: "10.0.0.1", Kind: "device"})
	c.MarkUsed("host")

	if err := c.Save(); err != nil {
		t.Fatalf("Save: %v", err)
	}

	c2 := New(path, 3600)
	if err := c2.Load(); err != nil {
		t.Fatalf("Load: %v", err)
	}

	results := c2.RecentlyUsed(1)
	if len(results) != 1 || results[0].Name != "host" {
		t.Errorf("LastUsed not persisted: %v", results)
	}
}

// tempFile writes content to a temp file and returns its path.
func tempFile(t *testing.T, content []byte) string {
	t.Helper()
	f, err := os.CreateTemp(t.TempDir(), "cache-*.json")
	if err != nil {
		t.Fatal(err)
	}
	if _, err := f.Write(content); err != nil {
		t.Fatal(err)
	}
	f.Close()
	return f.Name()
}