package adapter_test

import (
	"fmt"
	"go/parser"
	"go/token"
	"io/fs"
	"os"
	"path/filepath"
	"runtime"
	"strconv"
	"strings"
	"testing"
)

const (
	scriptoriumModulePath = "gitea.maximumdirect.net/eric/scriptorium"
	promptkitInternalPath = "gitea.maximumdirect.net/eric/promptkit/internal"
)

var (
	removedFrameworkPackageRoots = []string{
		scriptoriumModulePath + "/internal/artifact",
		scriptoriumModulePath + "/internal/domain",
		scriptoriumModulePath + "/internal/filecatalog",
		scriptoriumModulePath + "/internal/llm",
		scriptoriumModulePath + "/internal/profile",
		scriptoriumModulePath + "/internal/prompt",
		scriptoriumModulePath + "/internal/promptdef",
		scriptoriumModulePath + "/internal/usecase",
		scriptoriumModulePath + "/internal/validate",
	}
	removedFrameworkDirectories = []string{
		"internal/artifact",
		"internal/domain",
		"internal/filecatalog",
		"internal/llm",
		"internal/profile",
		"internal/prompt",
		"internal/promptdef",
		"internal/usecase",
		"internal/validate",
	}
	nonSourceDirectories = map[string]struct{}{
		".cache":           {},
		".codebase-memory": {},
		".git":             {},
		"build":            {},
		"coverage":         {},
		"dist":             {},
		"node_modules":     {},
		"out":              {},
		"testdata":         {},
		"vendor":           {},
	}
)

type forbiddenImport struct {
	filePath   string
	importPath string
}

func TestApplicationBoundary(t *testing.T) {
	moduleRoot := moduleRootFromTestFile(t)

	violations, err := findForbiddenProductionImports(moduleRoot)
	if err != nil {
		t.Fatalf("scan production imports: %v", err)
	}
	for _, violation := range violations {
		t.Errorf("%s imports forbidden package %s", violation.filePath, violation.importPath)
	}

	assertFrameworkImplementationAbsent(t, moduleRoot)
}

func TestForbiddenImportScannerDetectsFormerRoot(t *testing.T) {
	root := t.TempDir()
	sourcePath := writeGoSource(t, root, "nested/consumer/root.go", scriptoriumModulePath)

	violations, err := findForbiddenProductionImports(root)
	if err != nil {
		t.Fatalf("scan source fixture: %v", err)
	}
	assertSingleViolation(t, violations, sourcePath, scriptoriumModulePath)
}

func TestForbiddenImportScannerDetectsFormerFrameworkFamily(t *testing.T) {
	root := t.TempDir()
	importPath := scriptoriumModulePath + "/internal/profile/builtin"
	sourcePath := writeGoSource(t, root, "nested/consumer/profile.go", importPath)

	violations, err := findForbiddenProductionImports(root)
	if err != nil {
		t.Fatalf("scan source fixture: %v", err)
	}
	assertSingleViolation(t, violations, sourcePath, importPath)
}

func TestForbiddenImportScannerDetectsPromptkitInternalPackages(t *testing.T) {
	tests := []struct {
		name       string
		importPath string
	}{
		{name: "exact internal root", importPath: promptkitInternalPath},
		{name: "internal descendant", importPath: promptkitInternalPath + "/domain"},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			root := t.TempDir()
			sourcePath := writeGoSource(t, root, "nested/consumer/promptkit.go", tc.importPath)

			violations, err := findForbiddenProductionImports(root)
			if err != nil {
				t.Fatalf("scan source fixture: %v", err)
			}
			assertSingleViolation(t, violations, sourcePath, tc.importPath)
		})
	}
}

func TestForbiddenImportScannerAllowsRetainedApplicationPackages(t *testing.T) {
	root := t.TempDir()
	sourcePath := filepath.Join(root, "nested/consumer/application.go")
	if err := os.MkdirAll(filepath.Dir(sourcePath), 0o755); err != nil {
		t.Fatalf("create source fixture directory: %v", err)
	}
	source := `package consumer

import (
	_ "gitea.maximumdirect.net/eric/promptkit"
	_ "gitea.maximumdirect.net/eric/scriptorium/internal/adapter/http"
	_ "gitea.maximumdirect.net/eric/scriptorium/internal/config"
	_ "gitea.maximumdirect.net/eric/scriptorium/internal/defaults"
	_ "gitea.maximumdirect.net/eric/scriptorium/internal/format"
)
`
	if err := os.WriteFile(sourcePath, []byte(source), 0o644); err != nil {
		t.Fatalf("write source fixture: %v", err)
	}

	violations, err := findForbiddenProductionImports(root)
	if err != nil {
		t.Fatalf("scan source fixture: %v", err)
	}
	if len(violations) != 0 {
		t.Fatalf("expected retained application imports to be allowed, got %#v", violations)
	}
}

func findForbiddenProductionImports(root string) ([]forbiddenImport, error) {
	var violations []forbiddenImport
	err := filepath.WalkDir(root, func(path string, entry fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if entry.IsDir() {
			if path != root && shouldSkipSourceDirectory(entry.Name()) {
				return filepath.SkipDir
			}
			return nil
		}
		if !strings.HasSuffix(entry.Name(), ".go") || strings.HasSuffix(entry.Name(), "_test.go") {
			return nil
		}

		file, err := parser.ParseFile(token.NewFileSet(), path, nil, parser.ImportsOnly)
		if err != nil {
			return fmt.Errorf("parse imports in %s: %w", path, err)
		}
		for _, imported := range file.Imports {
			importPath, err := strconv.Unquote(imported.Path.Value)
			if err != nil {
				return fmt.Errorf("parse import path in %s: %w", path, err)
			}
			if isForbiddenProductionImport(importPath) {
				violations = append(violations, forbiddenImport{
					filePath:   path,
					importPath: importPath,
				})
			}
		}
		return nil
	})
	if err != nil {
		return nil, fmt.Errorf("walk repository root %s: %w", root, err)
	}
	return violations, nil
}

func shouldSkipSourceDirectory(name string) bool {
	_, skip := nonSourceDirectories[name]
	return skip
}

func isForbiddenProductionImport(importPath string) bool {
	if importPath == scriptoriumModulePath {
		return true
	}
	if importPath == promptkitInternalPath || strings.HasPrefix(importPath, promptkitInternalPath+"/") {
		return true
	}
	for _, root := range removedFrameworkPackageRoots {
		if importPath == root || strings.HasPrefix(importPath, root+"/") {
			return true
		}
	}
	return false
}

func moduleRootFromTestFile(t *testing.T) string {
	t.Helper()

	_, testFile, _, ok := runtime.Caller(0)
	if !ok {
		t.Fatal("locate dependency guard source")
	}
	root, err := findModuleRoot(filepath.Dir(testFile))
	if err != nil {
		t.Fatal(err)
	}
	return root
}

func findModuleRoot(start string) (string, error) {
	dir, err := filepath.Abs(start)
	if err != nil {
		return "", fmt.Errorf("resolve module search path: %w", err)
	}
	for {
		goMod := filepath.Join(dir, "go.mod")
		if info, err := os.Stat(goMod); err == nil && !info.IsDir() {
			return dir, nil
		} else if err != nil && !os.IsNotExist(err) {
			return "", fmt.Errorf("inspect %s: %w", goMod, err)
		}

		parent := filepath.Dir(dir)
		if parent == dir {
			return "", fmt.Errorf("locate go.mod from %s", start)
		}
		dir = parent
	}
}

func assertFrameworkImplementationAbsent(t *testing.T, moduleRoot string) {
	t.Helper()

	entries, err := os.ReadDir(moduleRoot)
	if err != nil {
		t.Fatalf("read module root: %v", err)
	}
	for _, entry := range entries {
		if !entry.IsDir() && strings.HasSuffix(entry.Name(), ".go") && !strings.HasSuffix(entry.Name(), "_test.go") {
			t.Errorf("module root contains production Go file %s", entry.Name())
		}
	}

	for _, relativePath := range removedFrameworkDirectories {
		path := filepath.Join(moduleRoot, filepath.FromSlash(relativePath))
		if _, err := os.Stat(path); err == nil {
			t.Errorf("removed framework directory still exists: %s", relativePath)
		} else if !os.IsNotExist(err) {
			t.Errorf("inspect removed framework directory %s: %v", relativePath, err)
		}
	}
}

func writeGoSource(t *testing.T, root, relativePath, importPath string) string {
	t.Helper()

	sourcePath := filepath.Join(root, filepath.FromSlash(relativePath))
	if err := os.MkdirAll(filepath.Dir(sourcePath), 0o755); err != nil {
		t.Fatalf("create source fixture directory: %v", err)
	}
	source := fmt.Sprintf("package consumer\n\nimport _ %q\n", importPath)
	if err := os.WriteFile(sourcePath, []byte(source), 0o644); err != nil {
		t.Fatalf("write source fixture: %v", err)
	}
	return sourcePath
}

func assertSingleViolation(t *testing.T, violations []forbiddenImport, sourcePath, importPath string) {
	t.Helper()

	if len(violations) != 1 {
		t.Fatalf("expected one forbidden import, got %#v", violations)
	}
	if violations[0].filePath != sourcePath {
		t.Fatalf("unexpected importing file: %q", violations[0].filePath)
	}
	if violations[0].importPath != importPath {
		t.Fatalf("unexpected forbidden import: %q", violations[0].importPath)
	}
}