/*
Copyright 2016 The Kubernetes Authors All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package rules

import (
	"fmt"
	"github.com/Masterminds/sprig"
	"io/ioutil"
	"k8s.io/helm/pkg/lint/support"
	"os"
	"path/filepath"
	"text/template"
)

// Templates lints a chart's templates.
func Templates(linter *support.Linter) {
	templatespath := filepath.Join(linter.ChartDir, "templates")

	templatesExist := linter.RunLinterRule(support.WarningSev, validateTemplatesExistence(linter, templatespath))

	// Templates directory is optional for now
	if !templatesExist {
		return
	}

	linter.RunLinterRule(support.ErrorSev, validateTemplatesDir(linter, templatespath))
	linter.RunLinterRule(support.ErrorSev, validateTemplatesParseable(linter, templatespath))
}

func validateTemplatesExistence(linter *support.Linter, templatesPath string) (lintError support.LintError) {
	if _, err := os.Stat(templatesPath); err != nil {
		lintError = fmt.Errorf("Templates directory not found")
	}
	return
}

func validateTemplatesDir(linter *support.Linter, templatesPath string) (lintError support.LintError) {
	fi, err := os.Stat(templatesPath)
	if err == nil && !fi.IsDir() {
		lintError = fmt.Errorf("'templates' is not a directory")
	}
	return
}

func validateTemplatesParseable(linter *support.Linter, templatesPath string) (lintError support.LintError) {
	tpl := template.New("tpl").Funcs(sprig.TxtFuncMap())

	lintError = filepath.Walk(templatesPath, func(name string, fi os.FileInfo, e error) error {
		if e != nil {
			return e
		}
		if fi.IsDir() {
			return nil
		}

		data, err := ioutil.ReadFile(name)
		if err != nil {
			lintError = fmt.Errorf("cannot read %s: %s", name, err)
			return lintError
		}

		newtpl, err := tpl.Parse(string(data))
		if err != nil {
			lintError = fmt.Errorf("error processing %s: %s", name, err)
			return lintError
		}
		tpl = newtpl
		return nil
	})

	return
}