// Copyright 2023 GoEdge CDN goedge.cdn@gmail.com. All rights reserved. Official site: https://goedge.cn .

package docs

import (
	"bytes"
	"github.com/TeaOSLab/EdgeUser/internal/web/actions/actionutils"
	"github.com/TeaOSLab/EdgeUser/internal/web/actions/default/docs/docutils"
	"github.com/iwind/TeaGo/Tea"
	"github.com/iwind/TeaGo/types"
	"github.com/yuin/goldmark"
	"io"
	"net/http"
	"os"
	"path/filepath"
	"regexp"
	"strings"
)

const URLPrefix = "/docs"

type IndexAction struct {
	actionutils.ParentAction
}

func (this *IndexAction) Init() {
	this.Nav("", "", "")
}

func (this *IndexAction) RunGet(params struct {
	Page string
}) {
	var docRoot = Tea.Root
	if Tea.IsTesting() {
		docRoot += "/../web"
	} else {
		docRoot += "/web"
	}
	docRoot += "/docs"

	docRoot = filepath.Clean(docRoot)

	var pageName = params.Page
	if strings.Contains(pageName, "..") { // prevent path traveling
		this.ResponseWriter.WriteHeader(http.StatusNotFound)
		this.WriteString("not found '" + params.Page + "'")
		return
	}
	if len(pageName) == 0 {
		pageName = "index.html"
	} else if strings.HasSuffix(pageName, "/") {
		pageName += "index.html"
	}

	// extension
	var ext = filepath.Ext(pageName)
	switch ext {
	case ".html":
		this.doHTML(docRoot, pageName)
	case ".jpg", ".jpeg", ".png", "gif", ".webp":
		this.doImage(docRoot, pageName, ext)
	default:
		this.ResponseWriter.WriteHeader(http.StatusNotFound)
		this.WriteString("not found '" + params.Page + "'")
	}
}

func (this *IndexAction) doHTML(docRoot string, pageName string) {
	pageName = strings.TrimSuffix(pageName, ".html")
	var path = filepath.Clean(docRoot + "/" + pageName + ".md")
	if !strings.HasPrefix(path, docRoot) {
		this.ResponseWriter.WriteHeader(http.StatusNotFound)
		this.WriteString("not found '" + pageName + "'")
		return
	}

	// convert links
	var rootURL = URLPrefix + "/"
	var pageDir = filepath.Dir(pageName)
	if len(pageDir) > 0 && pageDir != "." {
		rootURL += pageDir + "/"
	}

	resultData, err := docutils.ReadMarkdownFile(path, this.Data.GetString("teaName"), rootURL)
	if err != nil {
		this.ResponseWriter.WriteHeader(http.StatusNotFound)
		this.WriteString("not found '" + pageName + "'")
		return
	}

	// toc
	{
		var reg = regexp.MustCompile(`(?U)<h(\d)\sid="(.+)">(.*)</h\d>`)
		var subMatches = reg.FindAllStringSubmatch(string(resultData), -1)
		var tocItem = &TOCItem{
			Depth: 0,
		}
		var lastItem *TOCItem
		for _, subMatch := range subMatches {
			var depth = types.Int(subMatch[1])
			var id = subMatch[2]
			var title = subMatch[3]
			var item = &TOCItem{
				Depth:    depth,
				Id:       id,
				Title:    title,
				Children: []*TOCItem{},
				Parent:   nil,
			}

			if lastItem == nil {
				item.Parent = tocItem
				tocItem.Children = append(tocItem.Children, item)
			} else if lastItem.Depth == item.Depth {
				if lastItem.Parent != nil {
					item.Parent = lastItem.Parent
					lastItem.Parent.Children = append(lastItem.Parent.Children, item)
				}
			} else if lastItem.Depth < item.Depth {
				item.Parent = lastItem
				lastItem.Children = append(lastItem.Children, item)
			} else {
				var parent = lastItem.Parent
				for parent != nil {
					if parent.Depth == item.Depth {
						if parent.Parent != nil {
							item.Parent = parent.Parent
							parent.Parent.Children = append(parent.Parent.Children, item)
						}
						break
					}

					parent = parent.Parent
				}
			}

			lastItem = item
		}

		// reset parent
		tocItem.UnsetParent()

		if len(tocItem.Children) > 0 {
			this.Data["toc"] = tocItem.AsHTML()
		} else {
			this.Data["toc"] = ""
		}

		// format <h1...6>
		/**resultData = reg.ReplaceAllFunc(resultData, func(i []byte) []byte {
			var subMatch = reg.FindSubmatch(i)
			if len(subMatch) > 1 {
				var depth = subMatch[1]
				var idData = subMatch[2]
				var title = subMatch[3]
				return []byte("<a class=\"anchor\" id=\"" + string(idData) + "\">&nbsp;</a>\n<h" + string(depth) + ">" + string(title) + "</h" + string(depth) + ">")
			}
			return i
		})**/
	}

	this.Data["content"] = string(resultData)

	// 整体菜单
	this.readMenu(docRoot)

	this.Show()
}

func (this *IndexAction) doImage(docRoot string, pageName string, ext string) {
	var path = filepath.Clean(docRoot + "/" + pageName)
	if !strings.HasPrefix(path, docRoot) {
		this.ResponseWriter.WriteHeader(http.StatusNotFound)
		this.WriteString("not found '" + pageName + "'")
		return
	}

	var mimeType = ""
	switch ext {
	case ".jpg", ".jpeg":
		mimeType = "image/jpeg"
	case ".png":
		mimeType = "image/png"
	case ".webp":
		mimeType = "image/webp"
	case ".gif":
		mimeType = "image/gif"
	}

	if len(mimeType) == 0 {
		this.ResponseWriter.WriteHeader(http.StatusNotFound)
		return
	}

	stat, err := os.Stat(path)
	if err != nil {
		if os.IsNotExist(err) {
			this.ResponseWriter.WriteHeader(http.StatusNotFound)
			return
		}
		this.ErrorPage(err)
		return
	}

	this.ResponseWriter.Header().Set("Content-Length", types.String(stat.Size()))
	this.ResponseWriter.Header().Set("Content-Type", mimeType)

	fp, err := os.Open(path)
	if err != nil {
		this.ErrorPage(err)
		return
	}
	defer func() {
		_ = fp.Close()
	}()
	_, err = io.Copy(this.ResponseWriter, fp)
	if err != nil {
		this.ErrorPage(err)
		return
	}
}

func (this *IndexAction) readMenu(docRoot string) {
	var path = filepath.Clean(docRoot + "/@toc.md")
	data, err := os.ReadFile(path)
	if err != nil {
		this.ErrorPage(err)
		return
	}

	var markdown = goldmark.New()

	var buf = &bytes.Buffer{}
	err = markdown.Convert(data, buf)
	if err != nil {
		this.ErrorPage(err)
		return
	}

	var resultString = buf.String()
	var reg = regexp.MustCompile(`(?U)<a href="(.+)">`)
	resultString = reg.ReplaceAllStringFunc(resultString, func(s string) string {
		var match = reg.FindStringSubmatch(s)
		if len(match) > 1 {
			var link = match[1]
			var isExternal = strings.HasPrefix(link, "http://") || strings.HasPrefix(link, "https://")
			if !isExternal && !strings.HasPrefix(link, "/") {
				link = URLPrefix + "/" + link
			}
			if !isExternal && strings.HasSuffix(link, ".md") {
				link = strings.TrimSuffix(link, ".md") + ".html"
			}
			var a = `<a href="` + link + `"`

			// open external url in new window
			if isExternal {
				a += ` target="_blank"`
			}

			// active
			if link == this.Request.URL.Path {
				a += ` class="active"`
			}

			return a + ">"
		}
		return s
	})

	this.Data["rootTOC"] = resultString
}

type TOCItem struct {
	Depth    int        `json:"depth"`
	Id       string     `json:"id"`
	Title    string     `json:"title"`
	Children []*TOCItem `json:"children"`
	Parent   *TOCItem   `json:"-"`
}

func (this *TOCItem) UnsetParent() {
	this.Parent = nil
	for _, child := range this.Children {
		child.UnsetParent()
	}
}

func (this *TOCItem) AsHTML() string {
	if len(this.Children) == 0 || this.Depth >= 2 /** only 2 levels **/ {
		return "\n"
	}

	var space = strings.Repeat("  ", this.Depth)
	var result = space + "<ul>\n"

	for _, child := range this.Children {
		var childSpace = strings.Repeat("  ", child.Depth)
		result += childSpace + "<li><a href=\"#" + child.Id + "\">" + child.Title + "</a>\n" + child.AsHTML() + childSpace + "</li>\n"
	}

	result += space + "</ul>\n"

	return result
}