// Copyright 2021 The Hugo 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 hugolib

import (
	"io"
	"path/filepath"
	"strings"
	"time"

	"github.com/gohugoio/hugo/helpers"

	"github.com/gohugoio/hugo/source"

	"github.com/gohugoio/hugo/resources/page"

	"github.com/pkg/errors"
	"github.com/spf13/afero"
)

// ContentFactory creates content files from archetype templates.
type ContentFactory struct {
	h *HugoSites

	// We parse the archetype templates as Go templates, so we need
	// to replace any shortcode with a temporary placeholder.
	shortocdeReplacerPre  *strings.Replacer
	shortocdeReplacerPost *strings.Replacer
}

// AppplyArchetypeFilename archetypeFilename to w as a template using the given Page p as the foundation for the data context.
func (f ContentFactory) AppplyArchetypeFilename(w io.Writer, p page.Page, archetypeKind, archetypeFilename string) error {

	fi, err := f.h.SourceFilesystems.Archetypes.Fs.Stat(archetypeFilename)
	if err != nil {
		return err
	}

	if fi.IsDir() {
		return errors.Errorf("archetype directory (%q) not supported", archetypeFilename)
	}

	templateSource, err := afero.ReadFile(f.h.SourceFilesystems.Archetypes.Fs, archetypeFilename)
	if err != nil {
		return errors.Wrapf(err, "failed to read archetype file %q: %s", archetypeFilename, err)

	}

	return f.AppplyArchetypeTemplate(w, p, archetypeKind, string(templateSource))

}

// AppplyArchetypeFilename templateSource to w as a template using the given Page p as the foundation for the data context.
func (f ContentFactory) AppplyArchetypeTemplate(w io.Writer, p page.Page, archetypeKind, templateSource string) error {
	ps := p.(*pageState)
	if archetypeKind == "" {
		archetypeKind = p.Type()
	}

	d := &archetypeFileData{
		Type: archetypeKind,
		Date: time.Now().Format(time.RFC3339),
		Page: p,
		File: p.File(),
	}

	templateSource = f.shortocdeReplacerPre.Replace(templateSource)

	templ, err := ps.s.TextTmpl().Parse("archetype.md", string(templateSource))
	if err != nil {
		return errors.Wrapf(err, "failed to parse archetype template: %s", err)
	}

	result, err := executeToString(ps.s.Tmpl(), templ, d)
	if err != nil {
		return errors.Wrapf(err, "failed to execute archetype template: %s", err)
	}

	_, err = io.WriteString(w, f.shortocdeReplacerPost.Replace(result))

	return err

}

func (f ContentFactory) SectionFromFilename(filename string) string {
	filename = filepath.Clean(filename)
	rel, _ := f.h.AbsProjectContentDir(filename)
	if rel == "" {
		return ""
	}

	parts := strings.Split(helpers.ToSlashTrimLeading(rel), "/")
	if len(parts) < 2 {
		return ""
	}
	return parts[0]
}

// CreateContentPlaceHolder creates a content placeholder file inside the
// best matching content directory.
func (f ContentFactory) CreateContentPlaceHolder(filename string) (string, error) {
	filename = filepath.Clean(filename)
	_, abs := f.h.AbsProjectContentDir(filename)

	contentDir := filepath.Dir(abs)
	if err := f.h.Fs.Source.MkdirAll(contentDir, 0777); err != nil {
		return "", err
	}

	// This will be overwritten later, just write a placholder to get
	// the paths correct.
	placeholder := `---
title: "Content Placeholder"
_build:
  render: never
  list: never
  publishResources: false
---

`

	if err := afero.WriteFile(f.h.Fs.Source, abs, []byte(placeholder), 0777); err != nil {
		return "", err
	}

	return abs, nil
}

// NewContentFactory creates a new ContentFactory for h.
func NewContentFactory(h *HugoSites) ContentFactory {
	return ContentFactory{
		h: h,
		shortocdeReplacerPre: strings.NewReplacer(
			"{{<", "{x{<",
			"{{%", "{x{%",
			">}}", ">}x}",
			"%}}", "%}x}"),
		shortocdeReplacerPost: strings.NewReplacer(
			"{x{<", "{{<",
			"{x{%", "{{%",
			">}x}", ">}}",
			"%}x}", "%}}"),
	}
}

// archetypeFileData represents the data available to an archetype template.
type archetypeFileData struct {
	// The archetype content type, either given as --kind option or extracted
	// from the target path's section, i.e. "blog/mypost.md" will resolve to
	// "blog".
	Type string

	// The current date and time as a RFC3339 formatted string, suitable for use in front matter.
	Date string

	// The temporary page. Note that only the file path information is relevant at this stage.
	Page page.Page

	// File is the same as Page.File, embedded here for historic reasons.
	// TODO(bep) make this a method.
	source.File
}

func (f *archetypeFileData) Site() page.Site {
	return f.Page.Site()
}

func (f *archetypeFileData) Name() string {
	return f.Page.File().ContentBaseName()
}