// A via grant scoping autogroup:internet to a tag must surface only
// the matching exit node to the source — not strip every exit node
// from the source's view.
//
// Spec: https://tailscale.com/docs/features/access-control/grants/grants-via#route-users-through-exit-nodes-based-on-location
package v2

import (
	"net/netip"
	"slices"
	"testing"

	"github.com/juanfont/headscale/hscontrol/types"
	"github.com/stretchr/testify/require"
	"gorm.io/gorm"
	"tailscale.com/net/tsaddr"
	"tailscale.com/tailcfg"
)

// TestIssue3233ViaInternetExitVisibility loads a policy where alice's
// only access to autogroup:internet is via tag:exit1. Alice sees her
// tag:exit1 exit node as a peer with 0.0.0.0/0 + ::/0 in AllowedIPs,
// and does not see bob's tag:exit2 exit node.
func TestIssue3233ViaInternetExitVisibility(t *testing.T) {
	t.Parallel()

	users := types.Users{
		{Model: gorm.Model{ID: 1}, Name: "alice", Email: "alice@headscale.net"},
		{Model: gorm.Model{ID: 2}, Name: "bob", Email: "bob@headscale.net"},
	}

	exitRoutes := []netip.Prefix{tsaddr.AllIPv4(), tsaddr.AllIPv6()}

	aliceLaptop := node("alice-laptop", "100.64.0.10", "fd7a:115c:a1e0::a", users[0])
	aliceLaptop.ID = 1

	aliceExit := node("alice-exit", "100.64.0.11", "fd7a:115c:a1e0::b", users[0])
	aliceExit.ID = 2
	aliceExit.Tags = []string{"tag:exit1"}
	aliceExit.Hostinfo = &tailcfg.Hostinfo{RoutableIPs: exitRoutes}
	aliceExit.ApprovedRoutes = exitRoutes

	bobExit := node("bob-exit", "100.64.0.21", "fd7a:115c:a1e0::15", users[1])
	bobExit.ID = 3
	bobExit.Tags = []string{"tag:exit2"}
	bobExit.Hostinfo = &tailcfg.Hostinfo{RoutableIPs: exitRoutes}
	bobExit.ApprovedRoutes = exitRoutes

	nodes := types.Nodes{aliceLaptop, aliceExit, bobExit}

	policy := `{
		"tagOwners": {
			"tag:exit1": ["alice@headscale.net"],
			"tag:exit2": ["bob@headscale.net"]
		},
		"grants": [
			{
				"src": ["alice@headscale.net"],
				"dst": ["autogroup:internet"],
				"via": ["tag:exit1"],
				"ip": ["*"]
			}
		]
	}`

	pm, err := NewPolicyManager([]byte(policy), users, nodes.ViewSlice())
	require.NoError(t, err)

	t.Run("BuildPeerMap_includes_via_tagged_exit", func(t *testing.T) {
		t.Parallel()

		peerMap := pm.BuildPeerMap(nodes.ViewSlice())

		require.True(t,
			slices.ContainsFunc(peerMap[aliceLaptop.ID], func(n types.NodeView) bool {
				return n.ID() == aliceExit.ID
			}),
			"alice must see her tag:exit1 exit node as a peer")

		require.False(t,
			slices.ContainsFunc(peerMap[aliceLaptop.ID], func(n types.NodeView) bool {
				return n.ID() == bobExit.ID
			}),
			"alice must not see bob's tag:exit2 exit node — via grant scopes to tag:exit1")
	})

	t.Run("ViaRoutesForPeer_includes_exit_for_matching_tag", func(t *testing.T) {
		t.Parallel()

		result := pm.ViaRoutesForPeer(aliceLaptop.View(), aliceExit.View())
		require.Contains(t, result.Include, tsaddr.AllIPv4(),
			"alice viewing tag:exit1 exit must Include 0.0.0.0/0 — drives AllowedIPs in state.RoutesForPeer")
		require.Contains(t, result.Include, tsaddr.AllIPv6(),
			"alice viewing tag:exit1 exit must Include ::/0 — drives AllowedIPs in state.RoutesForPeer")
	})

	t.Run("ViaRoutesForPeer_excludes_exit_for_other_tag", func(t *testing.T) {
		t.Parallel()

		result := pm.ViaRoutesForPeer(aliceLaptop.View(), bobExit.View())
		require.Contains(t, result.Exclude, tsaddr.AllIPv4(),
			"alice viewing tag:exit2 exit must Exclude 0.0.0.0/0 — strips it from AllowedIPs")
		require.Contains(t, result.Exclude, tsaddr.AllIPv6(),
			"alice viewing tag:exit2 exit must Exclude ::/0 — strips it from AllowedIPs")
	})
}