package cache

import (
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"testing"
	"time"
)

func TestShortcutRejectsAmbiguousTargets(t *testing.T) {
	c := New("", 3600)
	c.Upsert(Entry{Name: "web.prod.example", IP: "10.0.0.1"})
	c.Upsert(Entry{Name: "web.dev.example", IP: "10.0.0.2"})
	normalize := func(s string) string { return strings.SplitN(s, ".", 2)[0] }
	for range 100 {
		entry, found, fresh, err := c.GetByShortcut("web", normalize)
		if err == nil || found || fresh || entry.Name != "" {
			t.Fatalf("ambiguous shortcut returned target: %+v, %v, %v, %v", entry, found, fresh, err)
		}
	}
}

func TestSaveMergesIndependentlyLoadedCaches(t *testing.T) {
	path := filepath.Join(t.TempDir(), "hosts.json")
	a, b := New(path, 3600), New(path, 3600)
	for _, c := range []*Cache{a, b} {
		if err := c.Load(); err != nil {
			t.Fatal(err)
		}
	}
	a.Upsert(Entry{Name: "a", IP: "10.0.0.1"})
	b.Upsert(Entry{Name: "b", IP: "10.0.0.2"})
	for _, c := range []*Cache{a, b} {
		if err := c.Save(); err != nil {
			t.Fatal(err)
		}
	}
	if err := a.Load(); err != nil {
		t.Fatal(err)
	}
	if len(a.All()) != 2 {
		t.Fatalf("lost an update: %+v", a.All())
	}

	// Saving a stale usage update must retain newer IPs and both usage times.
	if err := b.Load(); err != nil {
		t.Fatal(err)
	}
	b.MarkUsed("a")
	used, _ := b.Get("a")
	a.Upsert(Entry{Name: "a", IP: "10.0.0.3"})
	if err := a.Save(); err != nil {
		t.Fatal(err)
	}
	if err := b.Save(); err != nil {
		t.Fatal(err)
	}
	got, _ := b.Get("a")
	if got.IP != "10.0.0.3" || !got.LastUsed.Equal(used.LastUsed) {
		t.Fatalf("lost refreshed IP or usage: %+v", got)
	}

	b.Delete("a")
	if err := b.Save(); err != nil {
		t.Fatal(err)
	}
	if err := a.Load(); err != nil {
		t.Fatal(err)
	}
	if got, _ := a.Get("a"); got.Name != "" {
		t.Fatalf("deleted entry survived: %+v", got)
	}
	a.Clear()
	if err := a.Save(); err != nil {
		t.Fatal(err)
	}
	if err := b.Load(); err != nil {
		t.Fatal(err)
	}
	if len(b.All()) != 0 {
		t.Fatal("clear merged old entries back in")
	}
}

func TestSaveAcrossProcesses(t *testing.T) {
	if path := os.Getenv("NETSSH_TEST_CACHE_WRITER_PATH"); path != "" {
		c := New(path, 3600)
		if err := c.Load(); err != nil {
			t.Fatal(err)
		}
		c.Upsert(Entry{Name: os.Getenv("NETSSH_TEST_CACHE_WRITER_NAME"), IP: "10.0.0.1"})
		if err := c.Save(); err != nil {
			t.Fatal(err)
		}
		return
	}
	path := filepath.Join(t.TempDir(), "hosts.json")
	const writers = 8
	cmds := make([]*exec.Cmd, writers)
	for i := range cmds {
		cmd := exec.Command(os.Args[0], "-test.run=^TestSaveAcrossProcesses$")
		cmd.Env = append(os.Environ(), "NETSSH_TEST_CACHE_WRITER_PATH="+path, fmt.Sprintf("NETSSH_TEST_CACHE_WRITER_NAME=host-%d", i))
		cmd.Stdout, cmd.Stderr = os.Stdout, os.Stderr
		if err := cmd.Start(); err != nil {
			t.Fatal(err)
		}
		cmds[i] = cmd
	}
	for _, cmd := range cmds {
		if err := cmd.Wait(); err != nil {
			t.Error(err)
		}
	}
	c := New(path, 3600)
	if err := c.Load(); err != nil {
		t.Fatal(err)
	}
	if len(c.All()) != writers {
		t.Fatalf("lost concurrent updates: got %d, want %d", len(c.All()), writers)
	}
}

func TestSavePreservesNewerUsageFromDisk(t *testing.T) {
	path := filepath.Join(t.TempDir(), "hosts.json")
	a := New(path, 3600)
	a.Upsert(Entry{Name: "web", IP: "10.0.0.1", LastUsed: time.Now()})
	if err := a.Save(); err != nil {
		t.Fatal(err)
	}
	b := New(path, 3600)
	if err := b.Load(); err != nil {
		t.Fatal(err)
	}
	a.MarkUsed("web")
	used, _ := a.Get("web")
	if err := a.Save(); err != nil {
		t.Fatal(err)
	}
	b.Upsert(Entry{Name: "web", IP: "10.0.0.2"})
	if err := b.Save(); err != nil {
		t.Fatal(err)
	}
	got, _ := b.Get("web")
	if got.IP != "10.0.0.2" || !got.LastUsed.Equal(used.LastUsed) {
		t.Fatalf("lost data: %+v", got)
	}
}

func TestUsageSaveDoesNotRestoreRemovedHosts(t *testing.T) {
	for _, clear := range []bool{false, true} {
		t.Run(fmt.Sprintf("clear=%v", clear), func(t *testing.T) {
			path := filepath.Join(t.TempDir(), "hosts.json")
			a := New(path, 3600)
			a.Upsert(Entry{Name: "web", IP: "10.0.0.1"})
			if err := a.Save(); err != nil {
				t.Fatal(err)
			}
			b := New(path, 3600)
			if err := b.Load(); err != nil {
				t.Fatal(err)
			}
			b.MarkUsed("web")
			if clear {
				a.Clear()
			} else {
				a.Delete("web")
			}
			if err := a.Save(); err != nil {
				t.Fatal(err)
			}
			if err := b.Save(); err != nil {
				t.Fatal(err)
			}
			if len(b.All()) != 0 {
				t.Fatalf("usage update restored removed entry: %+v", b.All())
			}
		})
	}
}