package architecture

import (
	"go/ast"
	"go/parser"
	"go/token"
	"io/fs"
	"path/filepath"
	"strconv"
	"testing"
)

// Keep the backend error-model guideline executable, including aliased imports.
func TestErrorConstructorsUseProjectModel(t *testing.T) {
	root := filepath.Join("..", "..")
	err := filepath.WalkDir(root, func(path string, d fs.DirEntry, err error) error {
		if err != nil {
			return err
		}
		if d.IsDir() || filepath.Ext(path) != ".go" {
			return nil
		}
		fset := token.NewFileSet()
		file, err := parser.ParseFile(fset, path, nil, 0)
		if err != nil {
			return err
		}
		imports := map[string]string{}
		for _, imp := range file.Imports {
			pkg, err := strconv.Unquote(imp.Path.Value)
			if err != nil {
				return err
			}
			if pkg != "errors" && pkg != "fmt" {
				continue
			}
			alias := pkg
			if imp.Name != nil {
				alias = imp.Name.Name
			}
			if alias == "." {
				t.Errorf("%s: dot import obscures error constructors", path)
			}
			imports[alias] = pkg
		}
		ast.Inspect(file, func(n ast.Node) bool {
			call, ok := n.(*ast.CallExpr)
			if !ok {
				return true
			}
			sel, ok := call.Fun.(*ast.SelectorExpr)
			if !ok {
				return true
			}
			ident, ok := sel.X.(*ast.Ident)
			if !ok {
				return true
			}
			if (imports[ident.Name] == "errors" && sel.Sel.Name == "New") || (imports[ident.Name] == "fmt" && sel.Sel.Name == "Errorf") {
				t.Errorf("%s: use backend/shared/errors", fset.Position(call.Pos()))
			}
			return true
		})
		return nil
	})
	if err != nil {
		t.Fatal(err)
	}
}