// Copyright (C) 2017 Marius Schellenberger

package main

import (
	"html/template"
	"regexp"
	"strconv"
	"strings"

	"github.com/blevesearch/bleve/analysis"
	htmlFilter "github.com/blevesearch/bleve/analysis/char_filters/html_char_filter"
	"github.com/russross/blackfriday"
)

var filter = makeFilter()

func makeFilter() analysis.CharFilter {
	f, _ := htmlFilter.CharFilterConstructor(nil, nil)
	return f
}

var (
	reHeader   = regexp.MustCompile("(<h[1-6])>(.+)(</h[1-6]>)")
	reLink     = regexp.MustCompile(`id="(.+)">`)
	whiteSpace = regexp.MustCompile(`\s+`)
	reIndex    = regexp.MustCompile("<h([1-6])>(.+)</h[1-6]>")
	titleRe    = regexp.MustCompile("[^a-zA-Z0-9 -]+")
)

type rendered struct {
	Index template.HTML
	Text  template.HTML
	MD    string
	Raw   []byte
}

func (r *rendered) Article() *Article {
	return &Article{
		Index:  r.Index,
		Text:   r.Text,
		MD:     r.MD,
		Search: whiteSpace.ReplaceAllString(string(filter.Filter(r.Raw)), " "),
	}
}

func (r *rendered) Snippet() *Snippet {
	return &Snippet{
		Index: r.Index,
		Text:  r.Text,
		MD:    r.MD,
	}
}

func render(text string) *rendered {
	rend := blackfriday.MarkdownCommon([]byte(text))
	index, html := buildIndex(string(rend))
	html = strings.Replace(html, "<table>", `<table class="table">`, -1)
	html = strings.Replace(html, "</h1>", `</h1><hr>`, -1)
	html = strings.Replace(html, "<a", `<a target="_blank"`, -1)
	return &rendered{
		Index: template.HTML(index),
		Text:  template.HTML(html),
		MD:    text,
		Raw:   rend,
	}
}

func spaceReplace(s string) string {
	return strings.Replace(s, " ", "+", -1)
}

func makeLinkTitle(t string) (newTitle string, title string) {
	title = titleRe.ReplaceAllString(t, "")
	newTitle = spaceReplace(title)
	return
}

func buildIndex(html string) (string, string) {
	var ret string
	m := make(map[string]int)
	hn := reIndex.FindAllStringSubmatch(html, -1)
	html = reHeader.ReplaceAllString(html, `${1} id="${2}">${2}${3}`)
	html = reLink.ReplaceAllStringFunc(html, spaceReplace)
	for k, v := range hn {
		link, _ := makeLinkTitle(v[2])
		i := m[link]
		m[link] = i + 1
		newLink := link + strconv.Itoa(i)
		html = strings.Replace(html, link+`"`, newLink+`"`, 1)
		ret += before(hn, k)
		ret += `<li><a href="#` + newLink + `">` + v[2] + "</a>"
		ret += after(hn, k)
	}
	return ret, html
}

func before(arr [][]string, i int) string {
	c, _ := strconv.Atoi(arr[i][1])
	if c == 1 {
		return `<ul type="circle">`
	}
	return ""
}

func after(arr [][]string, i int) string {
	c, _ := strconv.Atoi(arr[i][1])
	if len(arr) <= i+1 {
		return closeTag(c-1) + "</ul>"
	}
	n, _ := strconv.Atoi(arr[i+1][1])
	if n == 1 {
		return closeTag(c-n) + "</ul>"
	} else if n < c {
		return closeTag(c - n)
	} else if n > c {
		return openTag(n - c)
	} else if n == c {
		return "</li>"
	}
	return ""
}

func openTag(j int) (ret string) {
	for i := 0; i < j; i++ {
		ret += `<ul type="circle"><li>`
	}
	if j > 1 {
		ret = strings.Replace(ret, "circle", "none", j-1)
	}
	ret = ret[0 : len(ret)-4]
	return
}

func closeTag(j int) (ret string) {
	for i := 0; i < j; i++ {
		ret += "</li></ul></li>"
	}
	if j > 1 {
		ret = strings.Replace(ret, "</li></li>", "</li>", -1)
	}
	return
}