package webapp

import (
	"encoding/json"
	"io"
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// stubCluster is a minimal ClusterView implementation used by the
// handler tests. It returns canned values so the JSON shape can be
// pinned without standing up a real raft group.
type stubCluster struct {
	stats        ClusterStats
	clusterIDOut string
	addrOut      string
}

func (s *stubCluster) Stats() ClusterStats { return s.stats }
func (s *stubCluster) ClusterID() string   { return s.clusterIDOut }
func (s *stubCluster) LocalAddr() string   { return s.addrOut }

// withClusterServer returns a test server whose ClusterView is the
// supplied stub. The first-run password path is also exercised so
// the session cookie is available for the cluster-endpoint probes.
// Returns the *httptest.Server, the underlying *Server, and the
// authenticated http.Client (cookie jar already populated).
func withClusterServer(t *testing.T, c ClusterView) (*httptest.Server, *Server, *http.Client) {
	t.Helper()
	srv := newTestServer(t, &stubRunner{id: "w-1"})
	srv.SetCluster(c)
	ts := newHTTPTestServer(t, srv)

	client, _ := loginAsFirstRun(t, ts.URL, srv)
	clearRequiresChange(t, srv)

	return ts, srv, client
}

// TestClusterStatus_NotConfigured verifies the 503 path when no
// cluster subsystem is attached to the webapp.
func TestClusterStatus_NotConfigured(t *testing.T) {
	srv := newTestServer(t, &stubRunner{id: "w-1"})
	ts := newHTTPTestServer(t, srv)
	c, _ := loginAsFirstRun(t, ts.URL, srv)
	clearRequiresChange(t, srv)

	resp, err := c.Get(ts.URL + "/web/api/cluster/status")
	require.NoError(t, err)
	defer resp.Body.Close() //nolint:errcheck
	assert.Equal(t, http.StatusServiceUnavailable, resp.StatusCode,
		"cluster status must 503 when no cluster is attached")
}

// TestClusterStatus_HappyPath verifies the JSON shape of the
// /web/api/cluster/status response when a stub cluster is attached.
func TestClusterStatus_HappyPath(t *testing.T) {
	stub := &stubCluster{
		stats: ClusterStats{
			NodeID:           "worker1",
			LocalAddr:        "127.0.0.1:17401",
			State:            "Leader",
			Leader:           "worker1",
			Term:             17,
			AppliedIndex:     42,
			LastIndex:        42,
			NumPeers:         2,
			Voters:           []string{"worker1", "worker2"},
			FSMChecks:        1,
			FSMMembers:       2,
			FSMConfigVersion: 7,
			FSMOutboxLen:     3,
			FSMPartition:     "steady",
		},
		clusterIDOut: "worker1",
		addrOut:      "127.0.0.1:17401",
	}
	ts, _, c := withClusterServer(t, stub)

	resp, err := c.Get(ts.URL + "/web/api/cluster/status")
	require.NoError(t, err)
	defer resp.Body.Close() //nolint:errcheck
	assert.Equal(t, http.StatusOK, resp.StatusCode)
	assert.Equal(t, "application/json; charset=utf-8", resp.Header.Get("Content-Type"))
	body, _ := io.ReadAll(resp.Body)

	var got clusterStatusResponse
	require.NoError(t, json.Unmarshal(body, &got))
	assert.Equal(t, "worker1", got.SelfID)
	assert.Equal(t, "Leader", got.Role)
	assert.EqualValues(t, 17, got.Term)
	assert.Equal(t, "worker1", got.LeaderID)
	assert.Equal(t, []string{"worker1", "worker2"}, got.Voters)
	assert.EqualValues(t, 42, got.AppliedIndex)
	assert.EqualValues(t, 42, got.CommitIndex)
	assert.Equal(t, 1, got.FSMChecks)
	assert.Equal(t, 2, got.FSMMembers)
	assert.EqualValues(t, 7, got.FSMConfigVersion)
	assert.Equal(t, 3, got.FSMOutboxLen)
	assert.Equal(t, "steady", got.FSMPartition)
	assert.Equal(t, "worker1", got.ClusterID)
	assert.Equal(t, "127.0.0.1:17401", got.LocalAddr)
}

// TestClusterStatus_FSMFieldsZeroByDefault pins the FSM-side fields
// to the zero value when the stub cluster does not set them. Guards
// against a future refactor accidentally widening the wire format
// with a non-zero default for a fresh cluster.
func TestClusterStatus_FSMFieldsZeroByDefault(t *testing.T) {
	stub := &stubCluster{
		stats: ClusterStats{
			NodeID: "worker1", State: "Follower", Leader: "worker2",
			Voters: []string{"worker1", "worker2"},
		},
		clusterIDOut: "worker1",
		addrOut:      "127.0.0.1:17401",
	}
	ts, _, c := withClusterServer(t, stub)

	resp, err := c.Get(ts.URL + "/web/api/cluster/status")
	require.NoError(t, err)
	defer resp.Body.Close() //nolint:errcheck
	body, _ := io.ReadAll(resp.Body)

	var got clusterStatusResponse
	require.NoError(t, json.Unmarshal(body, &got))
	assert.EqualValues(t, 0, got.FSMConfigVersion, "fresh cluster must report config_version 0")
	assert.Equal(t, 0, got.FSMOutboxLen, "fresh cluster must report outbox_len 0")
	assert.Equal(t, "", got.FSMPartition, "fresh cluster must report partition empty/zero")
}

// TestClusterStatus_RequiresSession ensures the cluster admin
// endpoint is gated by the session middleware.
func TestClusterStatus_RequiresSession(t *testing.T) {
	stub := &stubCluster{}
	srv := newTestServer(t, &stubRunner{id: "w-1"})
	srv.SetCluster(stub)
	ts := newHTTPTestServer(t, srv)

	// No session cookie — should redirect to login.
	client := httpClient()
	resp, err := client.Get(ts.URL + "/web/api/cluster/status")
	require.NoError(t, err)
	defer resp.Body.Close() //nolint:errcheck
	assert.Equal(t, http.StatusFound, resp.StatusCode,
		"cluster status must redirect to login without session")
	assert.Equal(t, "/web/login", resp.Header.Get("Location"))
}

// TestClusterApplyTestConfig_NotExposed verifies production requests cannot
// append a hardcoded config through the former debug endpoint.
func TestClusterApplyTestConfig_NotExposed(t *testing.T) {
	t.Setenv("WORKER_CLUSTER_DEBUG_APPLY", "true")
	ts, _, c := withClusterServer(t, &stubCluster{})

	resp, err := c.Post(ts.URL+"/web/api/cluster/apply-test-config", "", nil)
	require.NoError(t, err)
	defer resp.Body.Close() //nolint:errcheck
	assert.Equal(t, http.StatusNotFound, resp.StatusCode)
}

// TestSetClusterDetaches verifies SetCluster(nil) returns the server
// to the no-cluster-attached state (503 from the endpoints).
func TestSetClusterDetaches(t *testing.T) {
	srv := newTestServer(t, &stubRunner{id: "w-1"})
	stub := &stubCluster{}
	srv.SetCluster(stub)
	require.NotNil(t, srv.Cluster())

	srv.SetCluster(nil)
	require.Nil(t, srv.Cluster())

	ts := newHTTPTestServer(t, srv)
	c, _ := loginAsFirstRun(t, ts.URL, srv)
	clearRequiresChange(t, srv)

	resp, err := c.Get(ts.URL + "/web/api/cluster/status")
	require.NoError(t, err)
	defer resp.Body.Close() //nolint:errcheck
	assert.Equal(t, http.StatusServiceUnavailable, resp.StatusCode)
}