package noliteral

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

	astutils "git.frostfs.info/TrueCloudLab/linters/pkg/ast-utils"
	"github.com/mitchellh/mapstructure"
	"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"`
	DisablePackages  []string `mapstructure:"disable-packages"`
	ConstantsPackage string   `mapstructure:"constants-package"`
	Enable           bool     `mapstructure:"enable"`
}

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

func New(conf any) (*analysis.Analyzer, error) {
	var config Configuration
	config.Enable = true

	err := mapstructure.Decode(conf, &config)
	if err != nil {
		Config.Enable = true
		return LogsAnalyzer, nil
	}

	Config.TargetMethods = append(Config.TargetMethods, config.TargetMethods...)
	Config.ConstantsPackage = config.ConstantsPackage
	Config.DisablePackages = config.DisablePackages
	Config.Enable = config.Enable

	return LogsAnalyzer, nil
}

func run(pass *analysis.Pass) (interface{}, error) {
	if !Config.Enable {
		return nil, nil
	}
	for _, file := range pass.Files {
		ast.Inspect(file, func(n ast.Node) bool {
			switch v := n.(type) {
			// a := zap.Error()
			case *ast.AssignStmt:
				if _, ok := v.Rhs[0].(*ast.CallExpr); ok {
					return false
				}
			// a := &log.Error()
			case *ast.UnaryExpr:
				if _, ok := v.X.(*ast.CallExpr); ok && v.Op == token.AND {
					return false
				}
			// log.Error()
			case *ast.CallExpr:
				if expr, ok := n.(*ast.CallExpr); ok {
					return analyzeCallExpr(pass, expr, file)
				}
			}
			return true
		})
	}

	return nil, nil
}

func analyzeCallExpr(pass *analysis.Pass, expr *ast.CallExpr, file *ast.File) bool {
	isLog, _ := astutils.IsTargetMethod(expr.Fun, Config.TargetMethods)

	if !isLog || len(expr.Args) == 0 || astutils.HasNoLintComment(pass, expr.Pos()) {
		return false
	}

	if !astutils.IsStringValue(expr.Args[0]) {
		alias, _ := astutils.GetAliasByPkgName(file, Config.ConstantsPackage)
		if Config.ConstantsPackage == "" || astutils.GetPackageName(expr.Args[0]) == alias || astutils.GetPackageName(expr.Args[0]) == "" {
			return false
		}

		for _, pkgName := range Config.DisablePackages {
			if pkgName == astutils.GetPackageName(expr.Args[0]) {
				return false
			}
		}

		pass.Report(analysis.Diagnostic{
			Pos:            expr.Pos(),
			End:            expr.End(),
			Category:       LinterName,
			Message:        "Wrong package for constants",
			SuggestedFixes: nil,
		})
		return false
	}

	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
}