package youtube

import (
	"bytes"
	"context"
	"fmt"
	"log"
	"os"
	"path"
	"strings"
	"text/template"
	"time"

	"arimelody.space/vodular/scanner"
	"golang.org/x/oauth2"
	"google.golang.org/api/option"
	"google.golang.org/api/youtube/v3"
)

const (
	YT_CATEGORY_GAMING = "20"
	YT_CATEGORY_ENTERTAINMENT = "24"
)

type CategoryType int
const (
	CATEGORY_GAME CategoryType = iota
	CATEGORY_ENTERTAINMENT
)

type (
	Category struct {
		Name	string
		Type	CategoryType
		Url		string
	}

	Video struct {
		Title		string
		Category	*Category
		Part		int
		Date		time.Time
		Tags		[]string
		Filename	string
		SizeBytes	int64
	}
)

func BuildVideo(metadata *scanner.Metadata) (*Video, error) {
	videoDate, err := time.Parse("2006-01-02", metadata.Date)
	if err != nil {
		return nil, fmt.Errorf("failed to parse date from metadata: %v", err)
	}

	var category *Category = nil
	if metadata.Category != nil {
		category = &Category{
			Name: metadata.Category.Name,
			Type: CATEGORY_ENTERTAINMENT,
			Url: metadata.Category.Url,
		}
		var ok bool
		category.Type, ok = videoCategoryStringTypes[metadata.Category.Type]
		if !ok { category.Type = CATEGORY_ENTERTAINMENT }
	}

	return &Video{
		Title: metadata.Title,
		Category: category,
		Part: metadata.Part,
		Date: videoDate,
		Tags: metadata.Tags,
		Filename: path.Join(
			metadata.FootageDir,
			fmt.Sprintf(
				"%s-fullvod.mkv",
				videoDate.Format("2006-01-02"),
			)),
	}, nil
}

type (
	MetaCategory struct {
		Name	string
		Type	string
		Url		string
	}

	Metadata struct {
		Title		string
		Date		time.Time
		Category	*MetaCategory
		Part		int
	}

	Template struct {
		Title *template.Template
		Description *template.Template
		Tags []string
	}
)

var videoCategoryTypeStrings = map[CategoryType]string{
	CATEGORY_GAME: "gaming",
	CATEGORY_ENTERTAINMENT: "entertainment",
}
var videoCategoryStringTypes = map[string]CategoryType{
	"gaming": CATEGORY_GAME,
	"entertainment": CATEGORY_ENTERTAINMENT,
}
var videoYtCategory = map[CategoryType]string {
	CATEGORY_GAME: YT_CATEGORY_GAMING,
	CATEGORY_ENTERTAINMENT: YT_CATEGORY_ENTERTAINMENT,
}

var templateDir = "templates"
var tagsPath = path.Join(templateDir, "tags.txt")
var titlePath = path.Join(templateDir, "title.txt")
var descriptionPath = path.Join(templateDir, "description.txt")

const defaultTitleTemplate =
"{{.Title}} - {{FormatTime .Date \"02 Jan 2006\"}}"
const defaultDescriptionTemplate =
"Streamed on {{FormatTime .Date \"02 January 2006\"}}"

var templateFuncs = template.FuncMap{
	"FormatTime": func (time time.Time, format string) string {
		return time.Format(format)
	},
	"ToLower": func (str string) string {
		return strings.ToLower(str)
	},
	"ToUpper": func (str string) string {
		return strings.ToUpper(str)
	},
}

func FetchTemplates() (*Template, error) {
	tmpl := Template{}

	// tags
	if tagsFile, err := os.ReadFile(tagsPath); err == nil {
		tmpl.Tags = strings.Split(string(tagsFile), "\n")
	} else {
		if !os.IsNotExist(err) { return nil, err }

		log.Fatalf(
			"%s not found. No default tags will be used.",
			tagsPath,
		)
		tmpl.Tags = []string{}
	}

	// title
	titleTemplate := template.New("title").Funcs(templateFuncs)
	if titleFile, err := os.ReadFile(titlePath); err == nil {
		tmpl.Title, err = titleTemplate.Parse(string(titleFile))
		if err != nil {
			return nil, fmt.Errorf("failed to parse title template: %v", err)
		}
	} else {
		if !os.IsNotExist(err) { return nil, err }

		log.Fatalf(
			"%s not found. Falling back to default template:\n%s",
			titlePath,
			defaultTitleTemplate,
		)
		tmpl.Title, err = titleTemplate.Parse(defaultTitleTemplate)
		if err != nil { panic(err) }

		os.WriteFile(titlePath, []byte(defaultTitleTemplate), 0644)
	}

	// description
	descriptionTemplate := template.New("description").Funcs(templateFuncs,)
	if descriptionFile, err := os.ReadFile(descriptionPath); err == nil {
		tmpl.Description, err = descriptionTemplate.Parse(string(descriptionFile))
		if err != nil {
			return nil, fmt.Errorf("failed to parse description template: %v", err)
		}
	} else {
		if !os.IsNotExist(err) { return nil, err }

		log.Fatalf(
			"%s not found. Falling back to default template:\n%s",
			descriptionPath,
			defaultDescriptionTemplate,
		)
		tmpl.Description, err = descriptionTemplate.Parse(defaultDescriptionTemplate)
		if err != nil { panic(err) }

		os.WriteFile(descriptionPath, []byte(defaultDescriptionTemplate), 0644)
	}

	return &tmpl, nil
}

func BuildTemplate(video *Video, tmpl *template.Template) (string, error) {
	out := &bytes.Buffer{}

	var category *MetaCategory
	if video.Category != nil {
		category = &MetaCategory{
			Name: video.Category.Name,
			Type: videoCategoryTypeStrings[video.Category.Type],
			Url: video.Category.Url,
		}
	}

	err := tmpl.Execute(out, Metadata{
		Title: video.Title,
		Date: video.Date,
		Category: category,
		Part: video.Part,
	})

	return strings.TrimSpace(out.String()), err
}

func UploadVideo(
	ctx context.Context,
	tokenSource oauth2.TokenSource,
	video *Video,
	templates *Template,
) (*youtube.Video, error) {
	title, err := BuildTemplate(video, templates.Title)
	if err != nil { return nil, fmt.Errorf("failed to build title: %v", err) }
	description, err := BuildTemplate(video, templates.Description)
	if err != nil { return nil, fmt.Errorf("failed to build description: %v", err) }

	service, err := youtube.NewService(
		ctx,
		option.WithScopes(youtube.YoutubeUploadScope),
		option.WithTokenSource(tokenSource),
	)
	if err != nil {
		log.Fatalf("Failed to create youtube service: %v\n", err)
		return nil, err
	}

	videoService := youtube.NewVideosService(service)

	categoryId := YT_CATEGORY_ENTERTAINMENT
	if video.Category != nil {
		if cid, ok := videoYtCategory[video.Category.Type]; ok {
			categoryId = cid
		}
	}

	call := videoService.Insert([]string{
		"snippet", "status",
	}, &youtube.Video{
		Snippet: &youtube.VideoSnippet{
			Title: title,
			Description: description,
			Tags: append(templates.Tags, video.Tags...),
			CategoryId: categoryId, // gaming
		},
		Status: &youtube.VideoStatus{
			PrivacyStatus: "private",
		},
	}).NotifySubscribers(false)

	file, err := os.Open(video.Filename)
	if err != nil {
		log.Fatalf("Failed to open file: %v\n", err)
		return nil, err
	}
	call.Media(file)

	log.Println("Uploading video...")

	call.ProgressUpdater(func(current, total int64) {
		// for some reason, this only returns 0.
		// instead, we pull the file size from the ffmpeg output directly.
		if total == 0 { total = video.SizeBytes }
		fmt.Printf("Uploading... (%.2f%%)\n", float64(current) / float64(total) * 100)
	})
	ytVideo, err := call.Do()
	if err != nil {
		log.Fatalf("Failed to upload video: %v\n", err)
		return nil, err
	}

	return ytVideo, err
}