package finstr

import (
	"bytes"
	"errors"
	"flag"
	"fmt"
	goimg "image"
	"image/jpeg"
	"net/url"
	"os"
	"path"
	"path/filepath"
	"sort"
	"strings"
	"text/template"
	"time"
	"unicode"

	"git.fireandbrimst.one/aw/finstr/crop"
	"git.fireandbrimst.one/aw/finstr/initer"
	"git.fireandbrimst.one/aw/go-resize"
	goutil "git.fireandbrimst.one/aw/goutil/misc"
)

var dir string
var outdir string
var t *template.Template
var suffix string
var artsy bool

type link struct {
	Path  string
	Name  string
	Space bool
}

type image struct {
	FilenameMedium string
	FilenameSmall  string
}

type page struct {
	Title  string
	Links  []link
	Images []image
	Back   link
	Artsy  bool
}

func replaceFirst(s string, search string, replace string) string {
	return strings.Replace(s, search, replace, 1)
}

/*-------------------------*/

type calendarMonth struct {
	year  int
	month int
}

func (m calendarMonth) String() string {
	return fmt.Sprintf("%04d %v", m.year, time.Month(m.month).String())
}

func (m calendarMonth) laterThan(m2 calendarMonth) bool {
	if m.year == m2.year {
		return m.month > m2.month
	} else {
		return m.year > m2.year
	}
}

func byMonthDesc(m []calendarMonth) func(int, int) bool {
	return func(i, j int) bool { return m[i].laterThan(m[j]) }
}

/*-------------------------*/

type photo struct {
	filename string
	modified calendarMonth
	tags     []string
}

const dirImg = "img"

func dirOrig() string {
	return filepath.Join(dir, dirImg)
}

func dirMedium() string {
	return filepath.Join(outdir, "img_m")
}

func dirSmall() string {
	return filepath.Join(outdir, "img_k")
}

func dirPages() string {
	return filepath.Join(outdir, "pages")
}

func (p *photo) srcLocation(folder string) string {
	return replaceFirst(p.filename, dirOrig(), filepath.Base(folder))
}

func (p *photo) filenameMedium() string {
	return p.srcLocation(dirMedium())
}

func (p *photo) filenameSmall() string {
	return p.srcLocation(dirSmall())
}

func (p *photo) img() image {
	img := image{}
	img.FilenameMedium = p.filenameMedium()
	img.FilenameSmall = p.filenameSmall()
	return img
}

func byModified(p []photo) func(int, int) bool {
	return func(i, j int) bool {
		if p[i].modified == p[j].modified {
			return p[i].filename > p[j].filename
		} else {
			return p[i].modified.laterThan(p[j].modified)
		}
	}
}

/*-------------------------*/

func isASCII(r rune) bool {
	return r <= 127
}

func convASCII(s string) string {
	out := []rune(s)
	for i, c := range out {
		if (isASCII(c) && (unicode.IsLetter(c) || unicode.IsDigit(c))) || c == '.' {
			// keep unchanged
		} else if unicode.IsSpace(c) || unicode.IsPunct(c) {
			out[i] = '-'
		} else {
			out[i] = 'x'
		}
	}
	return string(out)
}

func filename(s string) string {
	return url.QueryEscape(convASCII(s))
}

func filenameDate(date calendarMonth) string {
	return fmt.Sprintf("%04d%02d", date.year, date.month)
}

/*-------------------------*/

func (p *page) String() string {
	buf := new(bytes.Buffer)
	p.Artsy = artsy
	err := t.Execute(buf, p)
	if err != nil {
		panic(err)
	}
	return buf.String()
}

func (p *page) write(name string) {
	goutil.OptPanic(goutil.WriteFile(filepath.Join(dirPages(), name+suffix), p.String()))
}

func singlePage(arg *pageArg, photos []photo) {
	sort.Slice(photos, byModified(photos))
	img := make([]image, 0)
	for _, p := range photos {
		img = append(img, p.img())
	}
	p := &page{Images: img, Title: arg.title(), Back: arg.back()}
	p.write(arg.filename())
}

/*-------------------------*/

type pageArg struct {
	tag  string
	date calendarMonth
}

func (arg *pageArg) filename() string {
	if arg.tag != "" {
		return filename(arg.tag)
	} else {
		return filenameDate(arg.date)
	}
}

func (arg *pageArg) title() string {
	if arg.tag != "" {
		return arg.tag
	} else {
		return arg.date.String()
	}
}

func (arg *pageArg) back() link {
	if arg.tag != "" {
		return link{Path: "ByTag.html", Name: "Back"}
	} else {
		return link{Path: "ByDate.html", Name: "Back"}
	}
}

/*-------------------------*/

type generator struct {
	photos []photo
}

func (g *generator) byTag() {
	l := make([]link, 0)
	photosWithTag := make(map[string][]photo)
	for _, photo := range g.photos {
		for _, tag := range photo.tags {
			photosWithTag[tag] = append(photosWithTag[tag], photo)
		}
	}
	tags := make([]string, 0)
	for tag := range photosWithTag {
		tags = append(tags, tag)
	}
	sort.Sort(sort.StringSlice(tags))
	for _, tag := range tags {
		photos := photosWithTag[tag]
		l = append(l, link{Path: filename(tag) + ".html", Name: tag})
		args := &pageArg{tag: tag}
		singlePage(args, photos)
	}
	back := link{Path: "index.html", Name: "Back"}
	p := &page{Links: l, Title: "photos by tag", Back: back}
	p.write("ByTag")
}

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

func (g *generator) byDate() {
	l := make([]link, 0)
	photosByMonth := make(map[calendarMonth][]photo)
	for _, photo := range g.photos {
		month := photo.modified
		photosByMonth[month] = append(photosByMonth[month], photo)
	}
	months := keys(photosByMonth)
	sort.Slice(months, byMonthDesc(months))
	for _, month := range months {
		photos := photosByMonth[month]
		l = append(l, link{Path: filenameDate(month) + ".html", Name: month.String(), Space: true})
		arg := &pageArg{date: month}
		singlePage(arg, photos)
	}
	back := link{Path: "index.html", Name: "Back"}
	p := page{Links: l, Title: "photos by date", Back: back}
	p.write("ByDate")
}

func (g *generator) index() {
	byDate := link{Path: "ByDate.html", Name: "By Date", Space: true}
	byTag := link{Path: "ByTag.html", Name: "By Tag"}
	l := []link{byDate, byTag}
	back := link{Path: "/", Name: "Home"}
	p := &page{Links: l, Title: "photos", Back: back}
	p.write("index")
}

func (g *generator) generate() {
	photoFiles := goutil.ListFilesExt(dirOrig(), ".jpg")
	tagFiles := goutil.ListFilesExt(dirOrig(), ".tags")
	photos := make(map[string]*photo)

	for _, photoFile := range photoFiles {
		name := goutil.TrimExt(path.Base(photoFile))
		stat, err := os.Stat(photoFile)
		goutil.OptPanic(err)
		modified := stat.ModTime()
		month := calendarMonth{year: modified.Year(), month: int(modified.Month())}
		photos[name] = &photo{filename: photoFile, modified: month}
	}
	for _, tagFile := range tagFiles {
		name := goutil.TrimExt(path.Base(tagFile))
		tagString, err := goutil.ReadFile(tagFile)
		goutil.OptPanic(err)
		tags := strings.Split(tagString, "\n")
		for _, tag := range tags {
			if _, ok := photos[name]; !ok {
				panic("No matching photo file for " + tagFile)
			}
			if tag = strings.TrimSpace(tag); tag != "" {
				photos[name].tags = append(photos[name].tags, tag)
			}
		}
	}
	for _, v := range photos {
		g.photos = append(g.photos, *v)
	}
	g.byDate()
	g.byTag()
	g.index()
}

func resizeAll(src string, dest string, w uint, h uint) {
	thumbnail := (w == h)
	rsz := func(w uint, h uint, img goimg.Image) goimg.Image { return resize.Resize(w, h, img, resize.Lanczos3) }
	files := goutil.ListFilesExt(src, ".jpg")
	for _, f := range files {
		outfile := filepath.Join(dest, strings.TrimPrefix(f, src))
		if goutil.PathExists(outfile) {
			continue
		}
		fmt.Println("Converting " + f)
		file, err := os.Open(f)
		goutil.OptPanic(err)
		img, err := jpeg.Decode(file)
		goutil.OptPanic(err)
		file.Close()
		var m goimg.Image
		if thumbnail {
			bounds := img.Bounds()
			if bounds.Dx() < bounds.Dy() {
				m = rsz(w, 0, img)
			} else {
				m = rsz(0, h, img)
			}
			if !artsy {
				m, err = crop.CropCenter(m, int(w), int(h))
				goutil.OptPanic(err)
			}
		} else {
			m = rsz(w, h, img)
		}
		out, err := os.Create(outfile)
		defer out.Close()
		goutil.OptPanic(err)
		goutil.OptPanic(jpeg.Encode(out, m, &jpeg.Options{Quality: 95}))
	}
}

func boundSize() {
	fmt.Println("making medium images")
	resizeAll(dirOrig(), dirMedium(), 0, 1080)
}

func makeThumbnails() {
	fmt.Println("making thumbnails")
	var size uint
	if artsy {
		size = 300
	} else {
		size = 200
	}
	resizeAll(dirMedium(), dirSmall(), size, size)
}

type Flags struct {
	InDir  string
	OutDir string
	Suffix string
	Clean  bool
}

func ensureFolders(clean bool) {
	outfolders := []string{dirMedium(), dirSmall(), dirPages()}
	for _, d := range outfolders {
		if clean {
			goutil.OptPanic(os.RemoveAll(d))
		}
		goutil.OptPanic(os.MkdirAll(d, 0755))
	}
}

func readStyle() {
	style, err := goutil.ReadFile(initer.InitFlag(dir))
	if err != nil {
		panic(err)
	}
	if strings.TrimSpace(style) == "artsy" {
		artsy = true
	} else {
		artsy = false
	}
}

func Generate(fl Flags) (e error) {
	defer func() {
		if r := recover(); r != nil {
			e = errors.New(fmt.Sprint("finstr: ", r))
		}
	}()
	dir = fl.InDir
	if fl.InDir != "" && fl.OutDir == "" {
		outdir = fl.InDir
	} else {
		outdir = fl.OutDir
	}
	suffix = fl.Suffix
	initer.InitializedOrDie(dir)
	ensureFolders(fl.Clean)
	readStyle()
	boundSize()
	makeThumbnails()
	pageTemplate, err := goutil.ReadFile(initer.TemplateFile(dir))
	if err != nil {
		return err
	}
	t = template.Must(template.New("site").Parse(pageTemplate))
	gen := &generator{}
	gen.generate()
	return nil
}

func Command() (goutil.CommandFlagsInit, goutil.CommandFunc) {
	f := Flags{}
	flagsInit := func(s *flag.FlagSet) {
		s.StringVar(&f.InDir, "in", "", "use 'in' directory as input instead of current working directory")
		s.StringVar(&f.OutDir, "out", "", "use 'out' directory as output instead of 'in' directory")
		s.StringVar(&f.Suffix, "suffix", ".html", "file extension of generated pages")
		s.BoolVar(&f.Clean, "clean", false, "remove old files in output directory before generating (use with caution)")
	}
	return flagsInit, func([]string) error {
		return Generate(f)
	}
}