package blog

import (
	"bytes"
	"fmt"
	"git.gutmet.org/goutil.git"
	. "git.gutmet.org/wombat.git/templatestructures"
	"math"
	"os"
	"path"
	"path/filepath"
	"sort"
	"strconv"
	"strings"
	"text/template"
	"time"
)

const postsPerPage int = 5

var blogname string
var folder string
var style string
var templateString string
var t *template.Template
var categories map[string][]post

type metadata struct {
	Title      string
	Date       time.Time
	Categories []string
}

type post struct {
	Content  string
	Meta     metadata
	Filename string
	Link     string
}

type categoryListing struct {
	Name      string
	ASCIIName string
	Posts     []post
}

func linkToPost(filename string) string {
	filename = filepath.Base(filename)
	split := strings.Split(filename, "-")
	if len(split) < 4 {
		return ""
	} else {
		year := split[0]
		month := split[1]
		day := split[2]
		name := ConvASCII(strings.Join(split[3:], "-"))
		return fmt.Sprintf("/%s/%s/%s/%s/%s", folder, year, month, day, name)
	}
}

func linkToCategory(name string) string {
	return fmt.Sprintf("/%s/categories.html#%s", folder, ConvASCII(strings.ToLower(name)))
}

func addToCategory(category string, post post) {
	c := strings.ToLower(category)
	if len(c) > 0 {
		categories[c] = append(categories[c], post)
	}
}

func keys(m map[string][]post) []string {
	keys := make([]string, 0)
	for k := range m {
		keys = append(keys, k)
	}
	return keys
}

func emitPostPage(post post) string {
	filename := strings.TrimPrefix(strings.TrimPrefix(post.Filename, "stage1/"), "stage1\\")
	link := post.Link
	os.Remove(filepath.Join("stage2", filename))
	base := path.Base(link)
	folders := strings.TrimSuffix("stage2"+link, base)
	os.MkdirAll(folders, 0755)
	page := Page{}
	page.Blogname = blogname
	page.Title = post.Meta.Title
	page.Style = style
	page.Content = post.Content
	page.Time = post.Meta.Date.Format(TimeFormat)
	page.Blogpost = true
	for _, categoryName := range post.Meta.Categories {
		page.Categories = append(page.Categories, Category{categoryName, linkToCategory(categoryName)})
		addToCategory(categoryName, post)
	}
	buf := new(bytes.Buffer)
	t.Execute(buf, page)
	goutil.WriteFile(filepath.Join("stage2", link), buf.String())
	return link
}

func indexFilename(i int) string {
	return filepath.Join("stage2", folder, fmt.Sprintf("%d.html", i))
}

func indexPageExists(i int, total int) bool {
	max := int(math.Ceil(float64(total)/float64(postsPerPage))) - 1
	return (i >= 0) && (i <= max)
}

type byDateDesc []post

func (p byDateDesc) Len() int           { return len(p) }
func (p byDateDesc) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
func (p byDateDesc) Less(i, j int) bool { return p[i].Meta.Date.After(p[j].Meta.Date) }

func emitIndexPage(i int, posts []post, total int) {
	file := indexFilename(i)
	postCollection := make([]Blogpost, 0)
	sort.Sort(byDateDesc(posts))
	for _, post := range posts {
		link := emitPostPage(post)
		p := Blogpost{}
		p.Title = post.Meta.Title
		p.Link = link
		p.Content = post.Content
		postCollection = append(postCollection, p)
	}
	buf := new(bytes.Buffer)
	page := Page{}
	page.Title = blogname
	page.Style = style
	page.Blogdir = folder
	page.Blogpost = false
	page.PostCollection = postCollection
	if indexPageExists(i-1, total) {
		page.Previous = strconv.Itoa(i-1) + ".html"
	}
	if indexPageExists(i+1, total) {
		page.Later = strconv.Itoa(i+1) + ".html"
	}
	t.Execute(buf, page)
	goutil.WriteFile(file, buf.String())
}

func getMetadata(file string) (metadata, error) {
	metaAll, err := goutil.ReadFile(goutil.TrimExt(file) + ".desc")
	ret := metadata{}
	if err == nil {
		lines := strings.Split(metaAll, "\n")
		for _, line := range lines {
			if strings.HasPrefix(line, "title:") {
				ret.Title = strings.Trim(strings.TrimPrefix(line, "title:"), "\" ")
			} else if strings.HasPrefix(line, "date:") {
				date, err2 := time.Parse(TimeFormat, strings.Trim(strings.TrimPrefix(line, "date:"), "\" "))
				if err2 == nil {
					ret.Date = date
				} else {
					fmt.Printf("Unrecognized date format in %s", file)
				}
			} else if strings.HasPrefix(line, "categories:") {
				categories := strings.Trim(strings.TrimPrefix(line, "categories:"), "\"[] ")
				splitcategories := strings.Split(categories, ",")
				for _, category := range splitcategories {
					c := strings.TrimSpace(category)
					if len(c) > 0 {
						ret.Categories = append(ret.Categories, c)
					}
				}
			}
		}
		return ret, nil
	} else {
		return ret, err
	}
}

func getPost(file string) (post, error) {
	tmp, err := goutil.ReadFile(file)
	if err == nil {
		meta, err2 := getMetadata(file)
		if err2 == nil {
			p := post{}
			p.Content = tmp
			p.Meta = meta
			p.Filename = file
			filename := strings.TrimPrefix(file, "stage1")
			p.Link = linkToPost(filename)
			return p, nil
		} else {
			return post{}, err2
		}
	} else {
		return post{}, err
	}
}

func makeCategories() {
	ct := template.Must(template.New("Categories").Parse(categoryTemplate))
	page := Page{}
	page.Title = blogname + ": Categories"
	page.Style = style
	keySet := keys(categories)
	sort.Strings(keySet)
	page.Content += "<dl style=\"padding-bottom:150em\">"
	for _, k := range keySet {
		listing := categoryListing{}
		listing.Name = k
		listing.ASCIIName = ConvASCII(k)
		sort.Sort(byDate(categories[k]))
		listing.Posts = categories[k]
		buf := new(bytes.Buffer)
		ct.Execute(buf, listing)
		page.Content += buf.String()
	}
	page.Content += "</dl>"
	buf := new(bytes.Buffer)
	t.Execute(buf, page)
	goutil.WriteFile(filepath.Join("stage2", folder, "categories.html"), buf.String())
}

func makeTimeline(posts []post) {
	sort.Sort(byDateDesc(posts))
	page := Page{}
	page.Title = blogname + ": Timeline"
	page.Style = style
	page.Content += "<dl>"
	year := -1
	month := -1
	for _, p := range posts {
		if year != p.Meta.Date.Year() {
			year = p.Meta.Date.Year()
			page.Content += "</dl>\n\n" + "<h3>" + strconv.Itoa(year) + "</h3>\n<dl>\n"
		}
		if month != int(p.Meta.Date.Month()) {
			month = int(p.Meta.Date.Month())
			page.Content += fmt.Sprintf("<dt>%02d</dt>", month)
		}
		page.Content += fmt.Sprintf("<dd><a href=\"%s\">%s</a></dd>\n", p.Link, p.Meta.Title)
	}
	page.Content += "</dl>"
	buf := new(bytes.Buffer)
	t.Execute(buf, page)
	goutil.WriteFile(filepath.Join("stage2", folder, "timeline.html"), buf.String())
}

type byDate []post

func (p byDate) Len() int           { return len(p) }
func (p byDate) Swap(i, j int)      { p[i], p[j] = p[j], p[i] }
func (p byDate) Less(i, j int) bool { return p[i].Meta.Date.Before(p[j].Meta.Date) }

func getPosts() []post {
	files := goutil.ListFilesExt(filepath.Join("stage1", folder), ".html")
	posts := make([]post, 0)
	for _, file := range files {
		tmp, err := getPost(file)
		if err == nil {
			posts = append(posts, tmp)
		}
	}
	return posts
}

func makeBlog() {
	posts := getPosts()
	sort.Sort(byDate(posts))
	total := len(posts)
	s := make([]post, 0)
	n := 0
	for i, tmp := range posts {
		if (i / postsPerPage) != n {
			emitIndexPage(n, s, total)
			n = i / postsPerPage
			s = make([]post, 0)
		}
		s = append(s, tmp)
	}
	if len(s) != 0 {
		emitIndexPage(n, s, total)
	}
	os.Link(indexFilename(n), filepath.Join("stage2", folder, "index.html"))
	makeCategories()
	makeTimeline(posts)
}

func Generate(dir string) {
	folder = dir
	blogname, _ = goutil.ReadFile(filepath.Join("stage0", folder, ".name"))
	if blogname == "" {
		blogname = "blog"
	}
	blogname = strings.TrimSpace(blogname)
	categories = make(map[string][]post)
	var err error
	var err2 error
	style, err = goutil.ReadFile("style.css")
	templateString, err2 = goutil.ReadFile("template")
	t = template.Must(template.New("page").Parse(templateString))
	if err == nil && err2 == nil {
		makeBlog()
	} else {
		fmt.Println(err)
		fmt.Println(err2)
	}
}

const categoryTemplate string = `
<dt><a name="{{.ASCIIName}}" class="categoryListing">{{.Name}}</a></dt>
{{range $index, $post := .Posts}}<dd><a href="{{$post.Link}}">{{$post.Meta.Title}}</a></dd>
{{end}}
`