package db

import (
	"database/sql"
	"errors"
	"testing"
	"time"
)

// seedCascadeFixture inserts a user and a single manifest. Returns the
// manifest's row id so callers can attach references (for the multi-arch case).
func seedCascadeFixture(t *testing.T, db *sql.DB, didStr, repo, digest string) string {
	t.Helper()

	user := &User{
		DID:         didStr,
		Handle:      "tester.example.com",
		PDSEndpoint: "https://test.pds.example.com",
		LastSeen:    time.Now(),
	}
	if err := UpsertUser(db, user); err != nil {
		t.Fatalf("UpsertUser: %v", err)
	}

	id, err := InsertManifest(db, &Manifest{
		DID:           didStr,
		Repository:    repo,
		Digest:        digest,
		HoldEndpoint:  "did:web:hold.example.com",
		SchemaVersion: 2,
		MediaType:     "application/vnd.oci.image.manifest.v1+json",
		CreatedAt:     time.Now(),
	})
	if err != nil {
		t.Fatalf("InsertManifest: %v", err)
	}
	return id
}

func TestGetTagDigest_ReturnsDigestForKnownTag(t *testing.T) {
	db, err := InitDB(":memory:", LibsqlConfig{})
	if err != nil {
		t.Fatalf("InitDB: %v", err)
	}
	defer db.Close()

	const did = "did:plc:tagdigest"
	const repo = "myapp"
	const digest = "sha256:aaa"

	seedCascadeFixture(t, db, did, repo, digest)

	if err := UpsertTag(db, &Tag{
		DID:        did,
		Repository: repo,
		Tag:        "latest",
		Digest:     digest,
		CreatedAt:  time.Now(),
	}); err != nil {
		t.Fatalf("UpsertTag: %v", err)
	}

	got, err := GetTagDigest(db, did, repo, "latest")
	if err != nil {
		t.Fatalf("GetTagDigest: %v", err)
	}
	if got != digest {
		t.Errorf("digest mismatch: got %q want %q", got, digest)
	}
}

func TestGetTagDigest_UnknownTagReturnsErrNoRows(t *testing.T) {
	db, err := InitDB(":memory:", LibsqlConfig{})
	if err != nil {
		t.Fatalf("InitDB: %v", err)
	}
	defer db.Close()

	seedCascadeFixture(t, db, "did:plc:tagdigest2", "myapp", "sha256:bbb")

	_, err = GetTagDigest(db, "did:plc:tagdigest2", "myapp", "does-not-exist")
	if !errors.Is(err, sql.ErrNoRows) {
		t.Errorf("expected sql.ErrNoRows for unknown tag, got %v", err)
	}
}

// TestShouldCascadeDeleteManifest_LastTagAndNoParent: the common case —
// digest has no remaining tags and is not referenced by any manifest list.
// Cascade should fire.
func TestShouldCascadeDeleteManifest_LastTagAndNoParent(t *testing.T) {
	db, err := InitDB(":memory:", LibsqlConfig{})
	if err != nil {
		t.Fatalf("InitDB: %v", err)
	}
	defer db.Close()

	const did = "did:plc:cascade1"
	const repo = "myapp"
	const digest = "sha256:lonely"

	seedCascadeFixture(t, db, did, repo, digest)

	// No tags pointing to this digest, no manifest_references entries.
	ok, err := ShouldCascadeDeleteManifest(db, did, digest)
	if err != nil {
		t.Fatalf("ShouldCascadeDeleteManifest: %v", err)
	}
	if !ok {
		t.Error("expected cascade=true when manifest is untagged and unreferenced")
	}
}

// TestShouldCascadeDeleteManifest_RemainingTagBlocks: another tag still
// points to this digest → keep the manifest alive.
func TestShouldCascadeDeleteManifest_RemainingTagBlocks(t *testing.T) {
	db, err := InitDB(":memory:", LibsqlConfig{})
	if err != nil {
		t.Fatalf("InitDB: %v", err)
	}
	defer db.Close()

	const did = "did:plc:cascade2"
	const repo = "myapp"
	const digest = "sha256:shared"

	seedCascadeFixture(t, db, did, repo, digest)

	if err := UpsertTag(db, &Tag{
		DID:        did,
		Repository: repo,
		Tag:        "v1",
		Digest:     digest,
		CreatedAt:  time.Now(),
	}); err != nil {
		t.Fatalf("UpsertTag: %v", err)
	}

	ok, err := ShouldCascadeDeleteManifest(db, did, digest)
	if err != nil {
		t.Fatalf("ShouldCascadeDeleteManifest: %v", err)
	}
	if ok {
		t.Error("expected cascade=false when another tag still points to the digest")
	}
}

// TestShouldCascadeDeleteManifest_TagInOtherRepoBlocks: the same digest is
// tagged in a *different* repository of the same user. The io.atcr.manifest
// record is keyed by digest alone, so one record backs both repos — cascading
// here would delete the record out from under the other repo and purge the
// shared layers on the hold, breaking an image the user never touched.
func TestShouldCascadeDeleteManifest_TagInOtherRepoBlocks(t *testing.T) {
	db, err := InitDB(":memory:", LibsqlConfig{})
	if err != nil {
		t.Fatalf("InitDB: %v", err)
	}
	defer db.Close()

	const did = "did:plc:cascade4"
	const deletingRepo = "myapp"
	const otherRepo = "myapp-mirror"
	const digest = "sha256:sharedacrossrepos"

	// Same content pushed to two repositories.
	seedCascadeFixture(t, db, did, deletingRepo, digest)
	if _, err := InsertManifest(db, &Manifest{
		DID:           did,
		Repository:    otherRepo,
		Digest:        digest,
		HoldEndpoint:  "did:web:hold.example.com",
		SchemaVersion: 2,
		MediaType:     "application/vnd.oci.image.manifest.v1+json",
		CreatedAt:     time.Now(),
	}); err != nil {
		t.Fatalf("InsertManifest(otherRepo): %v", err)
	}

	// Only the other repo still carries a tag. The deleting repo has none.
	if err := UpsertTag(db, &Tag{
		DID:        did,
		Repository: otherRepo,
		Tag:        "v1",
		Digest:     digest,
		CreatedAt:  time.Now(),
	}); err != nil {
		t.Fatalf("UpsertTag: %v", err)
	}

	ok, err := ShouldCascadeDeleteManifest(db, did, digest)
	if err != nil {
		t.Fatalf("ShouldCascadeDeleteManifest: %v", err)
	}
	if ok {
		t.Error("expected cascade=false when the digest is still tagged in another repository")
	}
}

// TestShouldCascadeDeleteManifest_MultiArchChildBlocks: the digest is a child
// of a manifest list (multi-arch parent). Even with no tags, deleting it
// would orphan the parent's reference, so we must NOT cascade.
func TestShouldCascadeDeleteManifest_MultiArchChildBlocks(t *testing.T) {
	db, err := InitDB(":memory:", LibsqlConfig{})
	if err != nil {
		t.Fatalf("InitDB: %v", err)
	}
	defer db.Close()

	const did = "did:plc:cascade3"
	const repo = "myapp"
	const childDigest = "sha256:amd64child"
	const parentDigest = "sha256:multiarchparent"

	// Insert the child manifest fixture.
	seedCascadeFixture(t, db, did, repo, childDigest)

	// Insert a separate parent (manifest list) and attach a manifest_reference
	// from parent → child.
	parentID, err := InsertManifest(db, &Manifest{
		DID:           did,
		Repository:    repo,
		Digest:        parentDigest,
		HoldEndpoint:  "did:web:hold.example.com",
		SchemaVersion: 2,
		MediaType:     "application/vnd.oci.image.index.v1+json",
		CreatedAt:     time.Now(),
	})
	if err != nil {
		t.Fatalf("InsertManifest(parent): %v", err)
	}

	if err := InsertManifestReference(db, &ManifestReference{
		ManifestKey:          parentID,
		Digest:               childDigest,
		Size:                 1234,
		MediaType:            "application/vnd.oci.image.manifest.v1+json",
		PlatformArchitecture: "amd64",
		PlatformOS:           "linux",
		ReferenceIndex:       0,
	}); err != nil {
		t.Fatalf("InsertManifestReference: %v", err)
	}

	ok, err := ShouldCascadeDeleteManifest(db, did, childDigest)
	if err != nil {
		t.Fatalf("ShouldCascadeDeleteManifest: %v", err)
	}
	if ok {
		t.Error("expected cascade=false when digest is a child of a manifest list")
	}
}