package pier_test

import (
	"context"
	"net/http"
	"strings"
	"testing"
	"time"

	"git.golem15.com/golem15/summercms/modules/pact"
	"github.com/alicebob/miniredis/v2"
	"github.com/modelcontextprotocol/go-sdk/mcp"
)

// Smoke tests of phase 19.7 plan 02 Task 3: Redis sessions shared by two
// pier instances on one miniredis (rehydration, binding, DELETE, idle TTL,
// the per-binding cap) and the pub/sub fan-out of subject events.

func TestPierSessionsSmoke(t *testing.T) {
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()
	mr := miniredis.RunT(t)
	cfg := "enabled: false\nsessions:\n  store: redis\n  idle_ttl: 30m\n  max_per_binding: 2\n"
	a := newInstance(t, mr, cfg, &acmeGuard{})
	b := newInstance(t, mr, cfg, &acmeGuard{})

	// Initialise on A, call on B: B rehydrates the session from Redis.
	sid := openSession(t, ctx, a, "oas_at_test")
	call := rpc(t, ctx, b.srv.URL+"/mcp", "oas_at_test", sid, callBody)
	if call.status != http.StatusOK || !strings.Contains(call.body, `\"principal\":7`) || strings.Contains(call.body, `"isError":true`) {
		t.Fatalf("call on B = %d %s", call.status, call.body)
	}
	keys := mr.Keys()
	if !containsPrefix(keys, "acme:mcp:s:") || !containsPrefix(keys, "acme:mcp:b:oauth:c1:7") {
		t.Fatalf("redis keys = %v, want acme:mcp:s:<id> and acme:mcp:b:oauth:c1:7", keys)
	}

	// Another binding presenting the same id is refused.
	other := rpc(t, ctx, b.srv.URL+"/mcp", "oas_at_other", sid, callBody)
	if other.status != http.StatusForbidden || !strings.Contains(other.body, "session_binding") {
		t.Fatalf("other binding = %d %s", other.status, other.body)
	}

	// DELETE on B ends the session everywhere: A answers 404 next.
	del, err := http.NewRequestWithContext(ctx, http.MethodDelete, b.srv.URL+"/mcp", nil)
	if err != nil {
		t.Fatal(err)
	}
	del.Header.Set("Authorization", "Bearer oas_at_test")
	del.Header.Set("Mcp-Session-Id", sid)
	resp, err := http.DefaultClient.Do(del)
	if err != nil {
		t.Fatal(err)
	}
	_ = resp.Body.Close()
	if resp.StatusCode != http.StatusNoContent {
		t.Fatalf("DELETE on B = %d", resp.StatusCode)
	}
	if gone := rpc(t, ctx, a.srv.URL+"/mcp", "oas_at_test", sid, callBody); gone.status != http.StatusNotFound {
		t.Fatalf("call on A after DELETE = %d %s", gone.status, gone.body)
	}

	// An idle session expires: after the TTL the id is unknown.
	expiring := openSession(t, ctx, a, "oas_at_test")
	mr.FastForward(31 * time.Minute)
	if expired := rpc(t, ctx, a.srv.URL+"/mcp", "oas_at_test", expiring, callBody); expired.status != http.StatusNotFound {
		t.Fatalf("call after the idle TTL = %d %s", expired.status, expired.body)
	}

	// max_per_binding + 1 initialisations answer 429.
	openSession(t, ctx, a, "oas_at_test")
	openSession(t, ctx, b, "oas_at_test")
	third := rpc(t, ctx, a.srv.URL+"/mcp", "oas_at_test", "", initializeBody)
	if third.status != http.StatusTooManyRequests || !strings.Contains(third.body, "too_many_sessions") {
		t.Fatalf("third session = %d %s", third.status, third.body)
	}
}

func TestPierFanOutSmoke(t *testing.T) {
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Second)
	defer cancel()
	mr := miniredis.RunT(t)
	guard := &acmeGuard{}
	cfg := "enabled: false\nsessions:\n  store: redis\n"
	a := newInstance(t, mr, cfg, guard)
	b := newInstance(t, mr, cfg, guard)

	changed := make(chan struct{}, 4)
	client := mcp.NewClient(&mcp.Implementation{Name: "acme-test", Version: "1"}, &mcp.ClientOptions{
		ToolListChangedHandler: func(context.Context, *mcp.ToolListChangedRequest) {
			select {
			case changed <- struct{}{}:
			default:
			}
		},
	})
	transport := &mcp.StreamableClientTransport{
		Endpoint:   b.srv.URL + "/mcp",
		HTTPClient: &http.Client{Transport: bearerTransport{token: "oas_at_test"}},
	}
	cs, err := client.Connect(ctx, transport, &mcp.ClientSessionOptions{ProtocolVersion: "2025-11-25"})
	if err != nil {
		t.Fatalf("connect: %v", err)
	}
	defer cs.Close()
	list, err := cs.ListTools(ctx, nil)
	if err != nil || len(list.Tools) != 1 {
		t.Fatalf("tools/list = %+v, %v", list, err)
	}

	// The guard now denies the tool; a permissions event fired on A reaches
	// the session on B as notifications/tools/list_changed.
	guard.deny.Store(true)
	if err := a.app.Events.Fire(ctx, &pact.MCPSubjectChanged{Guard: "acme", UserID: 7, Kind: pact.MCPSubjectPermissions}); err != nil {
		t.Fatal(err)
	}
	select {
	case <-changed:
	case <-time.After(10 * time.Second):
		t.Fatal("no tools/list_changed within 10 s")
	}
	list, err = cs.ListTools(ctx, nil)
	if err != nil || len(list.Tools) != 0 {
		t.Fatalf("tools/list after the permission change = %+v, %v", list, err)
	}

	// A revocation event ends the session: the next call is refused.
	if err := a.app.Events.Fire(ctx, &pact.MCPSubjectChanged{Guard: "acme", UserID: 7, Kind: pact.MCPSubjectRevoked}); err != nil {
		t.Fatal(err)
	}
	deadline := time.Now().Add(10 * time.Second)
	for {
		if _, err := cs.ListTools(ctx, nil); err != nil {
			break
		}
		if time.Now().After(deadline) {
			t.Fatal("the session survived the revocation event")
		}
		time.Sleep(50 * time.Millisecond)
	}
	if raw := rpc(t, ctx, b.srv.URL+"/mcp", "oas_at_test", cs.ID(), callBody); raw.status != http.StatusNotFound {
		t.Fatalf("call after revocation = %d %s", raw.status, raw.body)
	}
}