package processors

import (
	"fmt"
	"strings"

	"github.com/golangci/golangci-lint/pkg/lint/astcache"
	"github.com/golangci/golangci-lint/pkg/result"
)

type ageFileSummary struct {
	isGenerated bool
}

type ageFileSummaryCache map[string]*ageFileSummary

type AutogeneratedExclude struct {
	fileSummaryCache ageFileSummaryCache
	astCache         *astcache.Cache
}

func NewAutogeneratedExclude(astCache *astcache.Cache) *AutogeneratedExclude {
	return &AutogeneratedExclude{
		fileSummaryCache: ageFileSummaryCache{},
		astCache:         astCache,
	}
}

var _ Processor = &AutogeneratedExclude{}

func (p AutogeneratedExclude) Name() string {
	return "autogenerated_exclude"
}

func (p *AutogeneratedExclude) Process(issues []result.Issue) ([]result.Issue, error) {
	return filterIssuesErr(issues, p.shouldPassIssue)
}

func (p *AutogeneratedExclude) shouldPassIssue(i *result.Issue) (bool, error) {
	fs, err := p.getOrCreateFileSummary(i)
	if err != nil {
		return false, err
	}

	// don't report issues for autogenerated files
	return !fs.isGenerated, nil
}

// isGenerated reports whether the source file is generated code.
// Using a bit laxer rules than https://golang.org/s/generatedcode to
// match more generated code. See #48 and #72.
func isGeneratedFileByComment(doc string) bool {
	const (
		genCodeGenerated = "code generated"
		genDoNotEdit     = "do not edit"
		genAutoFile      = "autogenerated file" // easyjson
	)

	markers := []string{genCodeGenerated, genDoNotEdit, genAutoFile}
	doc = strings.ToLower(doc)
	for _, marker := range markers {
		if strings.Contains(doc, marker) {
			return true
		}
	}

	return false
}

func (p *AutogeneratedExclude) getOrCreateFileSummary(i *result.Issue) (*ageFileSummary, error) {
	fs := p.fileSummaryCache[i.FilePath()]
	if fs != nil {
		return fs, nil
	}

	fs = &ageFileSummary{}
	p.fileSummaryCache[i.FilePath()] = fs

	f := p.astCache.GetOrParse(i.FilePath())
	if f.Err != nil {
		return nil, fmt.Errorf("can't parse file %s: %s", i.FilePath(), f.Err)
	}

	fs.isGenerated = isGeneratedFileByComment(f.F.Doc.Text())
	return fs, nil
}

func (p AutogeneratedExclude) Finish() {}