package memory

import (
	"context"
	"fmt"
	"testing"

	"github.com/Tencent/WeKnora/internal/types"
	"github.com/stretchr/testify/require"
)

func conflictingMemoryProposal(t *testing.T, svc *Service, ctx context.Context) (*types.MemoryItem, *types.MemoryItem) {
	t.Helper()
	accepted, err := svc.Remember(ctx, types.MemoryItem{
		Kind: types.MemoryKindProfile, Topic: "database", Content: "My database is MySQL",
		Origin: types.MemoryOriginExplicit, Importance: 4,
	})
	require.NoError(t, err)
	proposal, err := svc.Remember(ctx, types.MemoryItem{
		Kind: types.MemoryKindProfile, Topic: "database", Content: "My database is PostgreSQL",
		Origin: types.MemoryOriginExtracted, Inferred: true, Importance: 4,
	})
	require.NoError(t, err)
	require.Equal(t, types.MemoryStatusPending, proposal.Status)
	return accepted, proposal
}

func TestPendingConflictPreservesAcceptedMemoryWhenRejected(t *testing.T) {
	svc, _, tenants := newMemoryHarness(t)
	ctx := enabledCtx(t, tenants, 1, "alice")
	accepted, proposal := conflictingMemoryProposal(t, svc, ctx)
	scope := scopeFor(t, ctx)

	prior, err := svc.repo.GetItem(ctx, scope, accepted.ID)
	require.NoError(t, err)
	require.Equal(t, types.MemoryStatusActive, prior.Status)
	require.Nil(t, prior.InvalidAt)
	require.Empty(t, prior.SupersededBy)
	recall := svc.Recall(ctx, "database")
	require.Contains(t, recall.Prompt, accepted.Content)
	require.NotContains(t, recall.Prompt, proposal.Content)
	require.Contains(t, svc.RetrievalContextFor(ctx).Background, accepted.Content)
	require.NotContains(t, svc.RetrievalContextFor(ctx).Background, proposal.Content)

	require.NoError(t, svc.RejectItem(ctx, proposal.ID))
	deleted, err := svc.repo.GetItem(ctx, scope, proposal.ID)
	require.NoError(t, err)
	require.Nil(t, deleted)
	prior, err = svc.repo.GetItem(ctx, scope, accepted.ID)
	require.NoError(t, err)
	require.Equal(t, types.MemoryStatusActive, prior.Status)
	require.Nil(t, prior.InvalidAt)
	require.Empty(t, prior.SupersededBy)
	require.Contains(t, svc.Recall(ctx, "database").Prompt, accepted.Content)

	_, err = svc.Remember(ctx, types.MemoryItem{
		Kind: proposal.Kind, Topic: proposal.Topic, Content: proposal.Content,
		Origin: types.MemoryOriginExtracted, Inferred: true,
	})
	require.ErrorIs(t, err, ErrPreviouslyForgotten)
}

func TestConfirmPendingConflictSupersedesOnlyAcceptedConflict(t *testing.T) {
	svc, _, tenants := newMemoryHarness(t)
	ctx := enabledCtx(t, tenants, 1, "alice")
	accepted, proposal := conflictingMemoryProposal(t, svc, ctx)
	unrelated, err := svc.Remember(ctx, types.MemoryItem{
		Kind: types.MemoryKindProfile, Topic: "role", Content: "I work as a data engineer",
	})
	require.NoError(t, err)
	confirmed, err := svc.ConfirmItem(ctx, proposal.ID)
	require.NoError(t, err)
	require.Equal(t, types.MemoryStatusActive, confirmed.Status)
	scope := scopeFor(t, ctx)
	prior, err := svc.repo.GetItem(ctx, scope, accepted.ID)
	require.NoError(t, err)
	require.Equal(t, types.MemoryStatusSuperseded, prior.Status)
	require.Equal(t, confirmed.ID, prior.SupersededBy)
	require.NotNil(t, prior.InvalidAt)
	require.Equal(t, accepted.Content, prior.Content)
	other, err := svc.repo.GetItem(ctx, scope, unrelated.ID)
	require.NoError(t, err)
	require.Equal(t, types.MemoryStatusActive, other.Status)
	recall := svc.Recall(ctx, "database")
	require.Contains(t, recall.Prompt, proposal.Content)
	require.NotContains(t, recall.Prompt, accepted.Content)

	_, err = svc.ConfirmItem(ctx, accepted.ID)
	require.ErrorIs(t, err, ErrItemNotPending, "historical memory must never be reactivated by confirmation")
	_, err = svc.ConfirmItem(ctx, confirmed.ID)
	require.ErrorIs(t, err, ErrItemNotPending)
	require.ErrorIs(t, svc.RejectItem(ctx, confirmed.ID), ErrItemNotPending,
		"a stale reject action must not delete a confirmed item")
	stillConfirmed, err := svc.repo.GetItem(ctx, scope, confirmed.ID)
	require.NoError(t, err)
	require.Equal(t, types.MemoryStatusActive, stillConfirmed.Status)
}

func TestConfirmPendingExtensionSupersedesContainedAcceptedMemory(t *testing.T) {
	svc, _, tenants := newMemoryHarness(t)
	ctx := enabledCtx(t, tenants, 1, "alice")
	accepted, err := svc.Remember(ctx, types.MemoryItem{
		Kind: types.MemoryKindProfile, Topic: "role", Content: "I maintain data pipelines",
	})
	require.NoError(t, err)
	proposal, err := svc.Remember(ctx, types.MemoryItem{
		Kind: types.MemoryKindProfile, Topic: "engineering", Content: "I maintain data pipelines in Go",
		Origin: types.MemoryOriginExtracted, Inferred: true,
	})
	require.NoError(t, err)
	prior, err := svc.repo.GetItem(ctx, scopeFor(t, ctx), accepted.ID)
	require.NoError(t, err)
	require.Equal(t, types.MemoryStatusActive, prior.Status)
	_, err = svc.ConfirmItem(ctx, proposal.ID)
	require.NoError(t, err)
	prior, err = svc.repo.GetItem(ctx, scopeFor(t, ctx), accepted.ID)
	require.NoError(t, err)
	require.Equal(t, types.MemoryStatusSuperseded, prior.Status)
	require.Equal(t, proposal.ID, prior.SupersededBy)
}

func TestMemoryReviewRejectsWrongStatusAndScope(t *testing.T) {
	svc, db, tenants := newMemoryHarness(t)
	ctx := enabledCtx(t, tenants, 1, "alice")
	_, proposal := conflictingMemoryProposal(t, svc, ctx)
	for _, foreignCtx := range []context.Context{
		enabledCtx(t, tenants, 1, "bob"),
		enabledCtx(t, tenants, 2, "alice"),
	} {
		foreignAccepted, foreignProposal := conflictingMemoryProposal(t, svc, foreignCtx)
		_, err := svc.ConfirmItem(foreignCtx, proposal.ID)
		require.ErrorIs(t, err, ErrItemNotFound)
		require.ErrorIs(t, svc.RejectItem(foreignCtx, proposal.ID), ErrItemNotFound)
		_, err = svc.ConfirmItem(foreignCtx, foreignProposal.ID)
		require.NoError(t, err)
		prior, err := svc.repo.GetItem(foreignCtx, scopeFor(t, foreignCtx), foreignAccepted.ID)
		require.NoError(t, err)
		require.Equal(t, types.MemoryStatusSuperseded, prior.Status)
	}
	stillPending, err := svc.repo.GetItem(ctx, scopeFor(t, ctx), proposal.ID)
	require.NoError(t, err)
	require.Equal(t, types.MemoryStatusPending, stillPending.Status)

	for _, status := range []string{types.MemoryStatusActive, types.MemoryStatusArchived, types.MemoryStatusSuperseded} {
		require.NoError(t, db.Model(&types.MemoryItem{}).Where("id = ?", proposal.ID).Update("status", status).Error)
		_, err := svc.ConfirmItem(ctx, proposal.ID)
		require.ErrorIs(t, err, ErrItemNotPending)
		require.ErrorIs(t, svc.RejectItem(ctx, proposal.ID), ErrItemNotPending)
		unchanged, err := svc.repo.GetItem(ctx, scopeFor(t, ctx), proposal.ID)
		require.NoError(t, err)
		require.Equal(t, status, unchanged.Status)
	}
	_, err = svc.ConfirmItem(ctx, "missing")
	require.ErrorIs(t, err, ErrItemNotFound)
}

func TestPendingConfirmationRollsBackOnWriteFailureAndRetries(t *testing.T) {
	for _, failingStatus := range []string{types.MemoryStatusSuperseded, types.MemoryStatusActive} {
		t.Run(failingStatus, func(t *testing.T) {
			svc, db, tenants := newMemoryHarness(t)
			ctx := enabledCtx(t, tenants, 1, "alice")
			accepted, proposal := conflictingMemoryProposal(t, svc, ctx)
			require.NoError(t, db.Exec(fmt.Sprintf(`CREATE TRIGGER fail_memory_review
				BEFORE UPDATE OF status ON memory_items WHEN NEW.status = '%s'
				BEGIN SELECT RAISE(ABORT, 'simulated review write failure'); END`, failingStatus)).Error)
			confirmed, err := svc.ConfirmItem(ctx, proposal.ID)
			require.ErrorContains(t, err, "simulated review write failure")
			require.Nil(t, confirmed)
			scope := scopeFor(t, ctx)
			prior, err := svc.repo.GetItem(ctx, scope, accepted.ID)
			require.NoError(t, err)
			require.Equal(t, types.MemoryStatusActive, prior.Status)
			require.Nil(t, prior.InvalidAt)
			require.Empty(t, prior.SupersededBy)
			pending, err := svc.repo.GetItem(ctx, scope, proposal.ID)
			require.NoError(t, err)
			require.Equal(t, types.MemoryStatusPending, pending.Status)
			require.NoError(t, db.Exec("DROP TRIGGER fail_memory_review").Error)

			confirmed, err = svc.ConfirmItem(ctx, proposal.ID)
			require.NoError(t, err)
			require.Equal(t, types.MemoryStatusActive, confirmed.Status)
			prior, err = svc.repo.GetItem(ctx, scope, accepted.ID)
			require.NoError(t, err)
			require.Equal(t, types.MemoryStatusSuperseded, prior.Status)
		})
	}
}

func TestPendingRejectionRollsBackTombstoneAndRetries(t *testing.T) {
	svc, db, tenants := newMemoryHarness(t)
	ctx := enabledCtx(t, tenants, 1, "alice")
	accepted, proposal := conflictingMemoryProposal(t, svc, ctx)
	require.NoError(t, db.Exec(`CREATE TRIGGER fail_memory_rejection
		BEFORE DELETE ON memory_items WHEN OLD.status = 'pending'
		BEGIN SELECT RAISE(ABORT, 'simulated review delete failure'); END`).Error)
	require.ErrorContains(t, svc.RejectItem(ctx, proposal.ID), "simulated review delete failure")
	scope := scopeFor(t, ctx)
	forgotten, err := svc.repo.HasTombstone(ctx, scope, types.MemoryFingerprint(proposal.Content))
	require.NoError(t, err)
	require.False(t, forgotten, "failed rejection must not prevent a later review")
	pending, err := svc.repo.GetItem(ctx, scope, proposal.ID)
	require.NoError(t, err)
	require.Equal(t, types.MemoryStatusPending, pending.Status)
	require.NoError(t, db.Exec("DROP TRIGGER fail_memory_rejection").Error)
	require.NoError(t, svc.RejectItem(ctx, proposal.ID))
	forgotten, err = svc.repo.HasTombstone(ctx, scope, types.MemoryFingerprint(proposal.Content))
	require.NoError(t, err)
	require.True(t, forgotten)
	prior, err := svc.repo.GetItem(ctx, scope, accepted.ID)
	require.NoError(t, err)
	require.Equal(t, types.MemoryStatusActive, prior.Status)
}

func TestPendingWriteFailurePreservesAcceptedMemoryAndRetries(t *testing.T) {
	svc, db, tenants := newMemoryHarness(t)
	ctx := enabledCtx(t, tenants, 1, "alice")
	accepted, err := svc.Remember(ctx, types.MemoryItem{
		Kind: types.MemoryKindProfile, Topic: "database", Content: "My database is MySQL",
	})
	require.NoError(t, err)
	proposal := types.MemoryItem{
		Kind: types.MemoryKindProfile, Topic: "database", Content: "My database is PostgreSQL",
		Origin: types.MemoryOriginExtracted, Inferred: true,
	}
	require.NoError(t, db.Exec(`CREATE TRIGGER fail_memory_proposal
		BEFORE INSERT ON memory_items WHEN NEW.status = 'pending'
		BEGIN SELECT RAISE(ABORT, 'simulated proposal insert failure'); END`).Error)
	_, err = svc.Remember(ctx, proposal)
	require.ErrorContains(t, err, "simulated proposal insert failure")
	prior, err := svc.repo.GetItem(ctx, scopeFor(t, ctx), accepted.ID)
	require.NoError(t, err)
	require.Equal(t, types.MemoryStatusActive, prior.Status)
	require.NoError(t, db.Exec("DROP TRIGGER fail_memory_proposal").Error)
	stored, err := svc.Remember(ctx, proposal)
	require.NoError(t, err)
	require.Equal(t, types.MemoryStatusPending, stored.Status)
	_, pendingCount, err := svc.ListItems(ctx, types.MemoryStatusPending, 10, 0)
	require.NoError(t, err)
	require.Equal(t, int64(1), pendingCount)
	prior, err = svc.repo.GetItem(ctx, scopeFor(t, ctx), accepted.ID)
	require.NoError(t, err)
	require.Equal(t, types.MemoryStatusActive, prior.Status)
}