package lighthouse_test

import (
	"context"
	"fmt"
	"strconv"
	"testing"
	"time"

	"git.golem15.com/golem15/summercms/modules/backpack"
	"git.golem15.com/golem15/summercms/modules/compass"
	"git.golem15.com/golem15/summercms/modules/lagoon"
	"git.golem15.com/golem15/summercms/modules/lighthouse"
	"gorm.io/gorm"
)

// newApp returns an app whose config selects a realtime driver.
func newApp(settings map[string]any) (*backpack.App, error) {
	cfg, err := compass.Open(compass.Options{Dir: "config", Env: "development", Environ: []string{}})
	if err != nil {
		return nil, err
	}
	for k, v := range settings {
		if err := cfg.Set(k, v); err != nil {
			return nil, err
		}
	}
	return backpack.New(cfg), nil
}

// isMember stands in for the application's own membership query.
func isMember(ctx context.Context, userID uint, blogID int64) bool {
	return userID == 42 && blogID == 7
}

func ExampleRegistry_Register() {
	app, err := newApp(map[string]any{"realtime.driver": "memory"})
	if err != nil {
		fmt.Println(err)
		return
	}
	svc, err := lighthouse.From(app)
	if err != nil {
		fmt.Println(err)
		return
	}

	// blog:{entity}:{id} channels are open to members of the blog only. The
	// authorizer runs on every subscribe; nothing is cached.
	err = svc.Registry().Register("blog", lighthouse.AuthorizerFunc(
		func(ctx context.Context, userID uint, channel string) lighthouse.Result {
			if isMember(ctx, userID, lighthouse.ChannelID(channel)) {
				return lighthouse.Allowed(nil)
			}
			return lighthouse.Denied("not a member of the blog")
		}))
	if err != nil {
		fmt.Println(err)
		return
	}

	for _, sub := range []struct {
		user    uint
		channel string
	}{{42, "blog:7"}, {42, "blog:8"}, {42, "presence:blog:7"}, {42, "shop:7"}} {
		ns, presence := lighthouse.ParseChannel(sub.channel)
		auth, ok := svc.Registry().Get(ns)
		if !ok {
			fmt.Println(sub.channel, "no authorizer")
			continue
		}
		res := auth.Authorize(context.Background(), sub.user, sub.channel)
		fmt.Printf("%d %s namespace=%s presence=%v allowed=%v reason=%q\n", sub.user, sub.channel, ns, presence, res.Allowed, res.Reason())
	}
	fmt.Println(lighthouse.ChannelID("blog:12abc"), lighthouse.FormatChannels("acme", []string{"Blog:7"}))
	// Output:
	// 42 blog:7 namespace=blog presence=false allowed=true reason=""
	// 42 blog:8 namespace=blog presence=false allowed=false reason="not a member of the blog"
	// 42 presence:blog:7 namespace=blog presence=true allowed=false reason="not a member of the blog"
	// shop:7 no authorizer
	// 12 [acme:blog:7]
}

// Post is the acme.blog post model. It knows nothing about realtime.
type Post struct {
	ID     uint   `gorm:"column:id;primaryKey"`
	BlogID uint   `gorm:"column:blog_id"`
	Title  string `gorm:"column:title"`
}

func (Post) TableName() string { return "acme_blog_posts" }

// bindPosts registers the broadcast contract of Post from the plugin's Boot.
func bindPosts(svc *lighthouse.Service) error {
	// docs:start bind
	return lighthouse.Bind[Post](svc, lighthouse.Binding[Post]{
		Alias: "blog.post",
		Channels: func(ctx context.Context, tx *gorm.DB, p *Post) ([]string, error) {
			return []string{"blog:" + strconv.FormatUint(uint64(p.BlogID), 10)}, nil
		},
	})
	// docs:end bind
}

// publishPost creates a post; its broadcast is published after commit.
func publishPost(ctx context.Context, db *gorm.DB, fail bool) error {
	// docs:start write
	return lagoon.Transaction(ctx, db, func(ctx context.Context, tx *gorm.DB) error {
		if err := tx.Create(&Post{BlogID: 7, Title: "Hello"}).Error; err != nil {
			return err
		}
		// The broadcast job is now queued in this transaction. It is
		// published only if the transaction commits.
		if fail {
			return fmt.Errorf("rolled back")
		}
		return nil
	})
	// docs:end write
}

// importPosts writes many posts and publishes one summary event.
func importPosts(ctx context.Context, svc *lighthouse.Service, db *gorm.DB, titles []string) error {
	// docs:start bulk
	return lighthouse.WithoutBroadcasting[Post](ctx, func(ctx context.Context) error {
		return lagoon.Transaction(ctx, db, func(ctx context.Context, tx *gorm.DB) error {
			for _, title := range titles {
				if err := tx.Create(&Post{BlogID: 7, Title: title}).Error; err != nil {
					return err
				}
			}
			return svc.Emit(ctx, tx, lighthouse.Broadcast{
				Channels: []string{"blog:7"},
				Event:    "blog.posts_imported",
				Payload: struct {
					Count int `json:"count"`
				}{len(titles)},
			})
		})
	})
	// docs:end bulk
}

// waitFor waits until the memory driver has recorded n publications.
func waitFor(t *testing.T, mem *lighthouse.MemoryDriver, n int) []lighthouse.Publication {
	t.Helper()
	deadline := time.Now().Add(10 * time.Second)
	for len(mem.Publications()) < n {
		if time.Now().After(deadline) {
			t.Fatalf("got %d publications, want %d", len(mem.Publications()), n)
		}
		time.Sleep(20 * time.Millisecond)
	}
	time.Sleep(300 * time.Millisecond) // catch extra publications
	pubs := mem.Publications()
	if len(pubs) != n {
		t.Fatalf("got %d publications, want exactly %d: %+v", len(pubs), n, pubs)
	}
	return pubs
}

// TestDocsBroadcast runs the bind, write and bulk regions of the Realtime
// page on the package's Postgres harness with a job worker.
func TestDocsBroadcast(t *testing.T) {
	_, svc, db := lighthouse.DocsEnv(t)
	if err := db.Exec(`CREATE TABLE acme_blog_posts (id SERIAL PRIMARY KEY, blog_id INTEGER NOT NULL, title TEXT NOT NULL)`).Error; err != nil {
		t.Fatal(err)
	}
	if err := bindPosts(svc); err != nil {
		t.Fatal(err)
	}
	mem, ok := svc.Driver().(*lighthouse.MemoryDriver)
	if !ok {
		t.Fatalf("driver is %T", svc.Driver())
	}
	ctx := t.Context()

	if err := publishPost(ctx, db, true); err == nil {
		t.Fatal("rolled-back publish succeeded")
	}
	if err := publishPost(ctx, db, false); err != nil {
		t.Fatal(err)
	}
	pubs := waitFor(t, mem, 1)
	if pubs[0].Event != "created.blog.post" || len(pubs[0].Channels) != 1 || pubs[0].Channels[0] != "blog:7" {
		t.Fatalf("publication = %+v", pubs[0])
	}

	if err := importPosts(ctx, svc, db, []string{"A", "B", "C"}); err != nil {
		t.Fatal(err)
	}
	pubs = waitFor(t, mem, 2)
	if pubs[1].Event != "blog.posts_imported" || string(pubs[1].Payload) != `{"count":3}` {
		t.Fatalf("summary = %+v %s", pubs[1], pubs[1].Payload)
	}
}