package sa5000

import (
	"honnef.co/go/tools/analysis/lint"
	"honnef.co/go/tools/analysis/report"
	"honnef.co/go/tools/go/ir"
	"honnef.co/go/tools/go/ir/irutil"
	"honnef.co/go/tools/internal/passes/buildir"

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

var SCAnalyzer = lint.InitializeAnalyzer(&lint.Analyzer{
	Analyzer: &analysis.Analyzer{
		Name:     "SA5000",
		Run:      run,
		Requires: []*analysis.Analyzer{buildir.Analyzer},
	},
	Doc: &lint.RawDocumentation{
		Title:    `Assignment to nil map`,
		Since:    "2017.1",
		Severity: lint.SeverityError,
		MergeIf:  lint.MergeIfAny,
	},
})

var Analyzer = SCAnalyzer.Analyzer

func run(pass *analysis.Pass) (interface{}, error) {
	for _, fn := range pass.ResultOf[buildir.Analyzer].(*buildir.IR).SrcFuncs {
		for _, block := range fn.Blocks {
			for _, ins := range block.Instrs {
				mu, ok := ins.(*ir.MapUpdate)
				if !ok {
					continue
				}
				c, ok := irutil.Flatten(mu.Map).(*ir.Const)
				if !ok {
					continue
				}
				if c.Value != nil {
					continue
				}
				report.Report(pass, mu, "assignment to nil map")
			}
		}
	}
	return nil, nil
}