package noliteral

import (
	"go/ast"
	"go/token"

	"golang.org/x/tools/go/analysis"
)

const LinterName = "noliteral"

var LogsAnalyzer = &analysis.Analyzer{
	Name: LinterName,
	Doc:  LinterName + " is a helper tool that ensures logging messages in Go code are structured and not written as simple text.",
	Run:  run,
}

type Configuration struct {
	TargetMethods []string `mapstructure:"target-methods"`
}

var Config = Configuration{
	TargetMethods: []string{"Debug", "Info", "Warn", "Error"},
}

func run(pass *analysis.Pass) (interface{}, error) {
	for _, file := range pass.Files {
		ast.Inspect(file, func(n ast.Node) bool {
			expr, ok := n.(*ast.CallExpr)
			if !ok {
				return true
			}

			isLog, _ := isLogDot(expr.Fun)
			if !isLog {
				return true
			}

			if len(expr.Args) == 0 || !isStringValue(expr.Args[0]) {
				return true
			}

			pass.Report(analysis.Diagnostic{
				Pos:            expr.Pos(),
				End:            expr.End(),
				Category:       LinterName,
				Message:        "Literals are not allowed in the body of the logger",
				SuggestedFixes: nil,
			})

			return false
		})
	}

	return nil, nil
}

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

	for _, method := range Config.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
}