// 🤖 SPIKE tests (issue #550 Part 4 v2). Live S3 tests are gated on
// LCHAT_TEST_S3_BUCKET; without it everything skips so `go test ./...`
// stays green on CI and dev machines with no AWS credentials.
package activator

import (
	"context"
	"crypto/rand"
	"database/sql"
	"encoding/hex"
	"errors"
	"fmt"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"github.com/aws/aws-sdk-go-v2/aws"
	awsconfig "github.com/aws/aws-sdk-go-v2/config"
	awss3 "github.com/aws/aws-sdk-go-v2/service/s3"
	s3types "github.com/aws/aws-sdk-go-v2/service/s3/types"
	"github.com/benbjohnson/litestream"

	_ "modernc.org/sqlite"
)

func liveConfig(t *testing.T) (bucket, prefix, region string) {
	t.Helper()
	bucket = os.Getenv("LCHAT_TEST_S3_BUCKET")
	if bucket == "" {
		t.Skip("LCHAT_TEST_S3_BUCKET not set; skipping live S3 spike test")
	}
	region = os.Getenv("LCHAT_TEST_S3_REGION")
	if region == "" {
		region = "eu-west-1"
	}
	b := make([]byte, 4)
	_, _ = rand.Read(b)
	prefix = fmt.Sprintf("spike/%d-%s", time.Now().Unix(), hex.EncodeToString(b))
	t.Cleanup(func() { cleanupPrefix(t, bucket, prefix, region) })
	return bucket, prefix, region
}

// seedDB creates a WAL-mode SQLite database via modernc.org/sqlite (the
// driver this repo already uses — no cgo anywhere in the test).
func seedDB(t *testing.T, path string) {
	t.Helper()
	db, err := sql.Open("sqlite", path)
	if err != nil {
		t.Fatalf("open sqlite: %v", err)
	}
	defer db.Close()
	if _, err := db.Exec(`PRAGMA journal_mode=WAL`); err != nil {
		t.Fatalf("wal mode: %v", err)
	}
	if _, err := db.Exec(`CREATE TABLE t (id INTEGER PRIMARY KEY, body TEXT)`); err != nil {
		t.Fatalf("create table: %v", err)
	}
	for i := 0; i < 50; i++ {
		if _, err := db.Exec(`INSERT INTO t (body) VALUES (?)`, fmt.Sprintf("row-%d", i)); err != nil {
			t.Fatalf("insert: %v", err)
		}
	}
}

func s3Client(t *testing.T, region string) *awss3.Client {
	t.Helper()
	cfg, err := awsconfig.LoadDefaultConfig(context.Background(), awsconfig.WithRegion(region))
	if err != nil {
		t.Fatalf("aws config: %v", err)
	}
	return awss3.NewFromConfig(cfg)
}

func listKeys(t *testing.T, bucket, prefix, region string) []string {
	t.Helper()
	client := s3Client(t, region)
	var keys []string
	p := awss3.NewListObjectsV2Paginator(client, &awss3.ListObjectsV2Input{
		Bucket: aws.String(bucket),
		Prefix: aws.String(prefix),
	})
	for p.HasMorePages() {
		out, err := p.NextPage(context.Background())
		if err != nil {
			t.Fatalf("list objects: %v", err)
		}
		for _, o := range out.Contents {
			keys = append(keys, *o.Key)
		}
	}
	return keys
}

// cleanupPrefix deletes every object AND version under the test prefix so
// spike runs leave nothing behind in the bucket.
func cleanupPrefix(t *testing.T, bucket, prefix, region string) {
	t.Helper()
	client := s3Client(t, region)
	ctx := context.Background()
	p := awss3.NewListObjectVersionsPaginator(client, &awss3.ListObjectVersionsInput{
		Bucket: aws.String(bucket),
		Prefix: aws.String(prefix),
	})
	for p.HasMorePages() {
		out, err := p.NextPage(ctx)
		if err != nil {
			t.Logf("cleanup list versions: %v", err)
			return
		}
		var objs []s3types.ObjectIdentifier
		for _, v := range out.Versions {
			objs = append(objs, s3types.ObjectIdentifier{Key: v.Key, VersionId: v.VersionId})
		}
		for _, m := range out.DeleteMarkers {
			objs = append(objs, s3types.ObjectIdentifier{Key: m.Key, VersionId: m.VersionId})
		}
		if len(objs) == 0 {
			continue
		}
		if _, err := client.DeleteObjects(ctx, &awss3.DeleteObjectsInput{
			Bucket: aws.String(bucket),
			Delete: &s3types.Delete{Objects: objs},
		}); err != nil {
			t.Logf("cleanup delete: %v", err)
		}
	}
}

// TestReplicateWithLease_ReplicatesToS3 proves Q1+Q2: the embedded library
// (pure Go, modernc driver) replicates a real database to S3 under a lease.
func TestReplicateWithLease_ReplicatesToS3(t *testing.T) {
	bucket, prefix, region := liveConfig(t)
	ctx := context.Background()

	dbPath := filepath.Join(t.TempDir(), "spike.db")
	seedDB(t, dbPath)

	r, err := ReplicateWithLease(ctx, dbPath, bucket, prefix, region)
	if err != nil {
		t.Fatalf("ReplicateWithLease: %v", err)
	}
	defer r.Close(ctx)

	if err := r.SyncAndWait(ctx); err != nil {
		t.Fatalf("SyncAndWait: %v", err)
	}

	keys := listKeys(t, bucket, prefix, region)
	t.Logf("objects under %s: %v", prefix, keys)
	var haveLock, haveLTX bool
	for _, k := range keys {
		if strings.HasSuffix(k, "lock.json") {
			haveLock = true
		}
		if strings.Contains(k, ".ltx") {
			haveLTX = true
		}
	}
	if !haveLock {
		t.Errorf("expected %s/lock.json in bucket, keys=%v", prefix, keys)
	}
	if !haveLTX {
		t.Errorf("expected replicated ltx data under %s, keys=%v", prefix, keys)
	}

	if err := r.Close(ctx); err != nil {
		t.Fatalf("Close: %v", err)
	}
}

// TestReplicateWithLease_MutualExclusion proves Q3: a second claimant on the
// same replica path fails LOUDLY at lease acquisition with a typed error —
// unlike the CLI, which silently absorbs the second writer.
func TestReplicateWithLease_MutualExclusion(t *testing.T) {
	bucket, prefix, region := liveConfig(t)
	ctx := context.Background()

	dir := t.TempDir()
	db1 := filepath.Join(dir, "one.db")
	db2 := filepath.Join(dir, "two.db")
	seedDB(t, db1)
	seedDB(t, db2)

	first, err := ReplicateWithLease(ctx, db1, bucket, prefix, region)
	if err != nil {
		t.Fatalf("first claimant: %v", err)
	}
	defer first.Close(ctx)

	// Second claimant, same bucket+prefix: must fail, and fail typed.
	second, err := ReplicateWithLease(ctx, db2, bucket, prefix, region)
	if err == nil {
		second.Close(ctx)
		t.Fatal("second claimant acquired the lease while the first held it — mutual exclusion broken")
	}
	var lexists *litestream.LeaseExistsError
	if !errors.As(err, &lexists) {
		t.Fatalf("second claimant failed, but not with *litestream.LeaseExistsError: %v", err)
	}
	t.Logf("second claimant failed loudly (typed): %v", err)
	t.Logf("  holder=%q expires=%s", lexists.Owner, lexists.ExpiresAt.Format(time.RFC3339))

	// Release, then the next claimant must succeed immediately (no TTL wait).
	if err := first.Close(ctx); err != nil {
		t.Fatalf("release: %v", err)
	}
	third, err := ReplicateWithLease(ctx, db2, bucket, prefix, region)
	if err != nil {
		t.Fatalf("claimant after release should succeed: %v", err)
	}
	if err := third.Close(ctx); err != nil {
		t.Fatalf("third close: %v", err)
	}
}