package astutils

import (
	"go/ast"
	"go/token"
	"strings"
	"sync"
)

type aliasCacheKey struct {
	File    *ast.File
	PkgName string
}

var (
	aliasCache = sync.Map{}
)

func IsTargetMethod(expr ast.Expr, targetMethods []string) (bool, string) {
	sel, ok := expr.(*ast.SelectorExpr)
	if !ok {
		return false, ""
	}

	for _, method := range targetMethods {
		if IsIdent(sel.Sel, method) {
			return true, method
		}
	}
	return false, ""
}

func IsIdent(expr ast.Expr, ident string) bool {
	id, ok := expr.(*ast.Ident)
	if ok && id.Name == ident {
		return true
	}

	return false
}

func IsStringValue(expr ast.Expr) bool {
	basicLit, ok := expr.(*ast.BasicLit)
	return ok && basicLit.Kind == token.STRING
}

func GetAliasByPkgName(file *ast.File, pkgName string) (string, error) {
	key := aliasCacheKey{File: file, PkgName: pkgName}
	if alias, ok := aliasCache.Load(key); ok {
		return alias.(string), nil
	}

	var alias string
	specs := file.Imports

	for _, spec := range specs {
		alias = GetAliasFromImportSpec(spec, pkgName)
		if alias != "" {
			break
		}
	}

	aliasCache.Store(key, alias)
	return alias, nil
}

func GetAliasFromImportSpec(spec *ast.ImportSpec, pkgName string) string {
	if spec == nil {
		return ""
	}
	importName := strings.Replace(spec.Path.Value, "\"", "", -1)
	if importName != pkgName {
		return ""
	}

	split := strings.Split(importName, "/")

	if len(split) == 0 {
		return ""
	}
	alias := split[len(split)-1]
	if spec.Name != nil {
		alias = spec.Name.Name
	}

	return alias
}

func GetPackageName(expr ast.Expr) string {
	if selectorExpr, ok := expr.(*ast.SelectorExpr); ok {
		if ident, ok := selectorExpr.X.(*ast.Ident); ok {
			return ident.Name
		}
	}
	return ""
}