package main

import (
	"context"
	"os"
	"path/filepath"
	"testing"

	"github.com/steveyegge/beads/internal/storage/sqlite"
	"github.com/steveyegge/beads/internal/types"
)

const (
	testIssueBD1 = "bd-1"
	testIssueBD2 = "bd-2"
)

// TestRemapCollisionsRemapsImportedNotExisting verifies the bug fix where collision
// resolution incorrectly modified existing issue dependencies.
//
// Bug (fixed): updateDependencyReferences() was updating ALL dependencies in the database
// based on the idMapping, without distinguishing between dependencies belonging to
// IMPORTED issues (should be updated) vs EXISTING issues (should NOT be touched).
//
// This test ensures existing issue dependencies are preserved during collision resolution.
func TestRemapCollisionsRemapsImportedNotExisting(t *testing.T) {
	// Setup: Create temporary database
	tmpDir, err := os.MkdirTemp("", "collision-bug-test-*")
	if err != nil {
		t.Fatalf("failed to create temp dir: %v", err)
	}
	defer os.RemoveAll(tmpDir)

	dbPath := filepath.Join(tmpDir, "test.db")
	store := newTestStoreWithPrefix(t, dbPath, "bd")

	ctx := context.Background()

	// Step 1: Create existing issues with dependencies
	existingIssues := []*types.Issue{
		{
			ID:          testIssueBD1,
			Title:       "Existing BD-1",
			Description: "Original database issue 1, depends on bd-2",
			Status:      types.StatusOpen,
			Priority:    2,
			IssueType:   types.TypeTask,
		},
		{
			ID:          testIssueBD2,
			Title:       "Existing BD-2",
			Description: "Original database issue 2",
			Status:      types.StatusOpen,
			Priority:    2,
			IssueType:   types.TypeTask,
		},
		{
			ID:          "bd-3",
			Title:       "Existing BD-3",
			Description: "Original database issue 3, depends on " + testIssueBD1,
			Status:      types.StatusOpen,
			Priority:    2,
			IssueType:   types.TypeTask,
		},
	}

	for _, issue := range existingIssues {
		if err := store.CreateIssue(ctx, issue, "test"); err != nil {
			t.Fatalf("failed to create existing issue %s: %v", issue.ID, err)
		}
	}

	// Add dependencies between existing issues
	dep1 := &types.Dependency{
		IssueID:     testIssueBD1,
		DependsOnID: testIssueBD2,
		Type:        types.DepBlocks,
	}
	dep2 := &types.Dependency{
		IssueID:     "bd-3",
		DependsOnID: testIssueBD1,
		Type:        types.DepBlocks,
	}
	if err := store.AddDependency(ctx, dep1, "test"); err != nil {
		t.Fatalf("failed to add dependency bd-1 → bd-2: %v", err)
	}
	if err := store.AddDependency(ctx, dep2, "test"); err != nil {
		t.Fatalf("failed to add dependency bd-3 → bd-1: %v", err)
	}

	// Step 2: Simulate importing issues with same IDs but different content
	importedIssues := []*types.Issue{
		{
			ID:          testIssueBD1,
			Title:       "Imported BD-1",
			Description: "From import",
			Status:      types.StatusOpen,
			Priority:    1,
			IssueType:   types.TypeTask,
		},
		{
			ID:          testIssueBD2,
			Title:       "Imported BD-2",
			Description: "From import",
			Status:      types.StatusOpen,
			Priority:    1,
			IssueType:   types.TypeTask,
		},
		{
			ID:          "bd-3",
			Title:       "Imported BD-3",
			Description: "From import",
			Status:      types.StatusOpen,
			Priority:    1,
			IssueType:   types.TypeTask,
		},
	}

	// Step 3: Detect collisions
	collisionResult, err := sqlite.DetectCollisions(ctx, store, importedIssues)
	if err != nil {
		t.Fatalf("collision detection failed: %v", err)
	}

	if len(collisionResult.Collisions) != 3 {
		t.Fatalf("expected 3 collisions, got %d", len(collisionResult.Collisions))
	}

	// Step 4: Resolve collisions
	allExisting, err := store.SearchIssues(ctx, "", types.IssueFilter{})
	if err != nil {
		t.Fatalf("failed to get existing issues: %v", err)
	}

	if err := sqlite.ScoreCollisions(ctx, store, collisionResult.Collisions, allExisting); err != nil {
		t.Fatalf("failed to score collisions: %v", err)
	}

	idMapping, err := sqlite.RemapCollisions(ctx, store, collisionResult.Collisions, allExisting)
	if err != nil {
		t.Fatalf("RemapCollisions failed: %v", err)
	}

	// Step 5: Verify existing issue dependencies are preserved
	t.Logf("\n=== Verifying Existing Issue Dependencies ===")

	// Check bd-1 → bd-2 dependency (created before import)
	existingDeps1, _ := store.GetDependencyRecords(ctx, "bd-1")
	t.Logf("bd-1 dependencies: %d (expected: 1)", len(existingDeps1))

	if len(existingDeps1) == 0 {
		t.Errorf("BUG CONFIRMED: Existing bd-1 has ZERO dependencies after import!")
		t.Errorf("  Expected: bd-1 → bd-2 (created by test before import)")
		t.Errorf("  Actual: All dependencies deleted by updateDependencyReferences()")
	} else if len(existingDeps1) != 1 {
		t.Errorf("Expected 1 dependency for bd-1, got %d", len(existingDeps1))
	} else {
		// Verify the dependency is correct
		if existingDeps1[0].DependsOnID != "bd-2" {
			t.Errorf("Expected bd-1 → bd-2, got bd-1 → %s", existingDeps1[0].DependsOnID)
		}
	}

	// Check bd-3 → bd-1 dependency (created before import)
	existingDeps3, _ := store.GetDependencyRecords(ctx, "bd-3")
	t.Logf("bd-3 dependencies: %d (expected: 1)", len(existingDeps3))

	if len(existingDeps3) == 0 {
		t.Errorf("BUG CONFIRMED: Existing bd-3 has ZERO dependencies after import!")
		t.Errorf("  Expected: bd-3 → bd-1 (created by test before import)")
		t.Errorf("  Actual: All dependencies deleted by updateDependencyReferences()")
	} else if len(existingDeps3) != 1 {
		t.Errorf("Expected 1 dependency for bd-3, got %d", len(existingDeps3))
	} else {
		// Verify the dependency is correct
		if existingDeps3[0].DependsOnID != testIssueBD1 {
			t.Errorf("Expected bd-3 → bd-1, got bd-3 → %s", existingDeps3[0].DependsOnID)
		}
	}

	t.Logf("\nID Mappings: %v", idMapping)
	t.Logf("Fix verified: Existing issue dependencies preserved during collision resolution")
}

// TestRemapCollisionsDoesNotUpdateNonexistentDependencies verifies that
// updateDependencyReferences is effectively a no-op during normal import flow,
// since imported dependencies haven't been added to the database yet when
// RemapCollisions runs.
//
// This test demonstrates that even if we had dependencies with the old imported IDs
// in the database, they are NOT touched because they don't have the NEW remapped IDs.
func TestRemapCollisionsDoesNotUpdateNonexistentDependencies(t *testing.T) {
	tmpDir, err := os.MkdirTemp("", "collision-noop-deps-*")
	if err != nil {
		t.Fatalf("failed to create temp dir: %v", err)
	}
	defer os.RemoveAll(tmpDir)

	dbPath := filepath.Join(tmpDir, "test.db")
	store := newTestStoreWithPrefix(t, dbPath, "bd")

	ctx := context.Background()

	// Step 1: Create existing issue with dependency
	existing1 := &types.Issue{
		ID:          testIssueBD1,
		Title:       "Existing BD-1",
		Description: "Original database issue",
		Status:      types.StatusOpen,
		Priority:    2,
		IssueType:   types.TypeTask,
	}
	existing2 := &types.Issue{
		ID:          testIssueBD2,
		Title:       "Existing BD-2",
		Description: "Original database issue",
		Status:      types.StatusOpen,
		Priority:    2,
		IssueType:   types.TypeTask,
	}
	if err := store.CreateIssue(ctx, existing1, "test"); err != nil {
		t.Fatalf("failed to create existing issue bd-1: %v", err)
	}
	if err := store.CreateIssue(ctx, existing2, "test"); err != nil {
		t.Fatalf("failed to create existing issue bd-2: %v", err)
	}

	// Add dependency between existing issues
	existingDep := &types.Dependency{
		IssueID:     testIssueBD1,
		DependsOnID: testIssueBD2,
		Type:        types.DepBlocks,
	}
	if err := store.AddDependency(ctx, existingDep, "test"); err != nil {
		t.Fatalf("failed to add existing dependency: %v", err)
	}

	// Step 2: Import colliding issues (without dependencies in DB)
	imported := []*types.Issue{
		{
			ID:          testIssueBD1,
			Title:       "Imported BD-1",
			Description: "From import, will be remapped",
			Status:      types.StatusOpen,
			Priority:    1,
			IssueType:   types.TypeTask,
		},
	}

	// Detect and resolve collisions
	collisionResult, err := sqlite.DetectCollisions(ctx, store, imported)
	if err != nil {
		t.Fatalf("collision detection failed: %v", err)
	}

	allExisting, _ := store.SearchIssues(ctx, "", types.IssueFilter{})
	if err := sqlite.ScoreCollisions(ctx, store, collisionResult.Collisions, allExisting); err != nil {
		t.Fatalf("failed to score collisions: %v", err)
	}

	// Now remap collisions - this should NOT touch the existing bd-1 → bd-2 dependency
	idMapping, err := sqlite.RemapCollisions(ctx, store, collisionResult.Collisions, allExisting)
	if err != nil {
		t.Fatalf("RemapCollisions failed: %v", err)
	}

	// Step 3: Verify existing dependency is untouched
	existingDeps, err := store.GetDependencyRecords(ctx, "bd-1")
	if err != nil {
		t.Fatalf("failed to get dependencies for bd-1: %v", err)
	}

	if len(existingDeps) != 1 {
		t.Errorf("Expected 1 dependency for existing bd-1, got %d (dependency should not be touched)", len(existingDeps))
	} else {
		if existingDeps[0].DependsOnID != testIssueBD2 {
			t.Errorf("Expected bd-1 → bd-2, got bd-1 → %s", existingDeps[0].DependsOnID)
		}
	}

	// Verify the remapped issue exists but has no dependencies
	// (because dependencies are imported later in Phase 5)
	remappedID := idMapping["bd-1"]
	remappedDeps, err := store.GetDependencyRecords(ctx, remappedID)
	if err != nil {
		t.Fatalf("failed to get dependencies for %s: %v", remappedID, err)
	}

	if len(remappedDeps) != 0 {
		t.Errorf("Expected 0 dependencies for remapped %s (dependencies added later), got %d",
			remappedID, len(remappedDeps))
	}

	t.Logf("Verified: updateDependencyReferences is effectively a no-op when no remapped dependencies exist")
}