package main

import (
	"context"
	_ "embed"
	"encoding/json"
	"fmt"
	"log"
	"math"
	"os"
	"path"
	"strings"

	"golang.org/x/oauth2"
	"golang.org/x/oauth2/google"
	"google.golang.org/api/option"
	"google.golang.org/api/youtube/v3"

	"arimelody.space/vodular/config"
	"arimelody.space/vodular/oauth"
	"arimelody.space/vodular/scanner"
	vid "arimelody.space/vodular/video"
	yt "arimelody.space/vodular/youtube"
)

//go:embed res/help.txt
var helpText string

const SEGMENT_EXTENSION = "mkv"
const MAX_TITLE_LEN = 100
const MAX_DESCRIPTION_LEN = 5000

func main() {
	ctx := context.Background()

	// config
	userConfigDir, err := os.UserConfigDir()
	if err != nil {
		log.Fatalf("Could not determine user configuration directory: %v", err)
	}
	config.CONFIG_FILENAME = path.Join(userConfigDir, "vodular", "config.toml")
	cfg, err := config.ReadConfig(config.CONFIG_FILENAME)
	if err != nil {
		log.Fatalf("Failed to read config: %v", err)
	}
	if cfg == nil {
		err = os.MkdirAll(path.Dir(config.CONFIG_FILENAME), 0750)
		if err != nil {
			log.Fatalf("Failed to create config directory: %v", err)
		}
		err = config.GenerateConfig(config.CONFIG_FILENAME)
		if err != nil {
			log.Fatalf("Failed to generate config: %v", err)
		}
		log.Printf(
			"New config file created (%s). " +
			"Please edit this file before running again!",
			config.CONFIG_FILENAME,
		)
		os.Exit(0)
	}

	var verbose bool = false
	var initDirectory bool = false
	var logout bool = false
	var keepConcatVOD bool = false
	var forceUpload bool = false
	var dryRun bool = false
	var directory string = ""

	for i, arg := range os.Args {
		if i == 0 { continue }
		if strings.HasPrefix(arg, "-") {
			switch arg {

			case "-h":
				fallthrough
			case "--help":
				log.Fatal(helpText)

			case "-v":
				fallthrough
			case "--verbose":
				verbose = true

			case "--dry-run":
				dryRun = true

			case "-f":
				fallthrough
			case "--force":
				forceUpload = true

			case "--init":
				initDirectory = true

			case "--keep-vod":
				keepConcatVOD = true

			case "--logout":
				logout = true

			default:
				fmt.Fprintf(os.Stderr, "Unknown option `%s`\n", arg)
				os.Exit(1)

			}
		} else {
			directory = arg
		}
	}

	if !strings.HasPrefix(directory, "/") {
		if wd, err := os.Getwd(); err != nil {
			directory = path.Join(directory, wd)
		}
	}

	// logout (--logout)
	if logout {
		cfg.Token = nil
		err = config.WriteConfig(cfg, config.CONFIG_FILENAME)
		if err != nil {
			log.Fatalf("Failed to write config: %v", err)
		}
		log.Fatalf("Logged out successfully.")
	}

	// initialising directory (--init)
	if initDirectory {
		err = scanner.InitialiseDirectory(directory)
		if err != nil {
			log.Fatalf("Failed to initialise directory: %v", err)
		}
		log.Fatalf(
			"Directory successfully initialised. " +
			"Be sure to update %s before uploading!",
			scanner.METADATA_FILENAME,
		)
	}

	// good to have early on
	templates, err := yt.FetchTemplates(path.Join(userConfigDir, "vodular", "templates"))
	if err != nil {
		log.Fatalf("Failed to fetch templates: %v", err)
	}

	// read directory metadata
	metadata, err := scanner.ReadMetadata(directory)
	if err != nil {
		if os.IsNotExist(err) {
			log.Fatalf("Directory does not exist: %s", directory)
		}
		log.Fatalf("Failed to fetch VOD metadata: %v", err)
	}
	if metadata == nil {
		log.Fatal(
			"Directory contained no metadata. " +
			"Use `--init` to initialise this directory.",
		)
	}

	// default footage directory
	footageDir := directory
	if len(metadata.FootageDir) >= 0 && !strings.HasPrefix(metadata.FootageDir, "/") {
		footageDir = path.Join(directory, metadata.FootageDir)
	}

	// scan for VOD segments
	vodFiles, err := scanner.ScanSegments(footageDir, SEGMENT_EXTENSION)
	if err != nil {
		log.Fatalf("Failed to fetch VOD filenames: %v", err)
	}
	if len(vodFiles) == 0 {
		log.Fatalf(
			"Directory contained no VOD files (expecting .%s)",
			SEGMENT_EXTENSION,
		)
	}
	if verbose {
		enc := json.NewEncoder(os.Stdout)
		enc.SetIndent("", "\t")
		log.Print("[ Metadata ]")
		log.Printf("Title: %s", metadata.Title)
		log.Printf("Part: %d", metadata.Part)
		log.Printf("Date: %s", metadata.Date.String())
		log.Printf(
			"Category: `%s` - %s (%s)",
			metadata.Category.Type,
			metadata.Category.Name,
			metadata.Category.Url,
		)
		log.Printf("Tags: %s", strings.Join(metadata.Tags, ", "))
		log.Printf("VOD files: [ %s ]", strings.Join(vodFiles, ", "))
	}

	// scan for thumbnail
	var thumbnail *yt.ThumbnailMetadata
	thumbnailPath, thumbnailSizeBytes, err := scanner.ScanThumbnail(directory)
	if err != nil {
		log.Fatalf("Failed to fetch thumbnail: %v", err)
	} else {
		thumbnail = &yt.ThumbnailMetadata{
			Filepath: thumbnailPath,
			SizeBytes: thumbnailSizeBytes,
		}
	}

	// build video template for upload
	videoMeta, err := yt.BuildVideo(metadata)
	if err != nil {
		log.Fatalf("Failed to build video template: %v", err)
	}
	title, err := yt.BuildTemplate(videoMeta, templates.Title)
	if err != nil {
		log.Fatalf("Failed to build video title: %v", err)
	}
	description, err := yt.BuildTemplate(videoMeta, templates.Description)
	if err != nil {
		log.Fatalf("Failed to build video description: %v", err)
	}
	if len(title) > 100 {
		log.Fatalf(
			"Video title length exceeds %d characters (%d). YouTube may reject this!",
			MAX_TITLE_LEN,
			len(videoMeta.Title),
		)
	}
	if len(description) > 5000 {
		log.Fatalf(
			"Video description length exceeds %d characters (%d). YouTube may reject this!",
			MAX_DESCRIPTION_LEN,
			len(description),
		)
	}
	if verbose {
		log.Print()
		log.Printf("[ TITLE ]\n\n%s\n\n", title)
		log.Printf("[ DESCRIPTION ]\n\n%s\n\n", description)
	}

	// youtube oauth flow
	oauth2Config := &oauth2.Config{
		ClientID: cfg.Google.ClientID,
		ClientSecret: cfg.Google.ClientSecret,
		Endpoint: google.Endpoint,
		Scopes: []string{ youtube.YoutubeScope },
		RedirectURL: cfg.RedirectUri,
	}
	var token *oauth2.Token
	if cfg.Token != nil {
		token = cfg.Token
	} else {
		token, err = oauth.GenerateToken(&ctx, oauth2Config, cfg)
		if err != nil {
			log.Fatalf("OAuth flow failed: %v", err)
		}
		cfg.Token = token
	}
	tokenSource := oauth2Config.TokenSource(ctx, token)
	if err != nil {
		log.Fatalf("Failed to create OAuth2 token source: %v", err)
	}
	if err = config.WriteConfig(cfg, config.CONFIG_FILENAME); err != nil {
		log.Fatalf("Failed to save OAuth token: %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)
	}

	// skip uploading if already done
	if (metadata.Uploaded || len(metadata.UploadURL) > 0) && !forceUpload {
		if len(metadata.UploadURL) > 0 {
			log.Printf("VOD has already been uploaded: %s", metadata.UploadURL)
		} else {
			log.Println("VOD has already been uploaded.")
		}
		if !dryRun {
			log.Printf(
				"To upload anyways, use --force or update %s.",
				scanner.METADATA_FILENAME,
			)
		}

		if len(metadata.UploadURL) > 0 {
			if !dryRun {
				videoId := strings.TrimPrefix(metadata.UploadURL, yt.VIDEO_URL_BASE)
				if videoId == metadata.UploadURL {
					log.Fatal("can't parse video ID from upload URL")
				}

				log.Println("Updating metadata...")
				if err = yt.UpdateMetadata(ctx, tokenSource, service, videoMeta, videoId, templates); err != nil {
					log.Printf("update metadata: %v", err)
				}

				log.Println("Uploading thumbnail...")
				if err = yt.UploadThumbnail(ctx, tokenSource, service, videoId, thumbnail); err != nil {
					log.Printf("upload thumbnail: %v", err)
				}
			} else {
				log.Print("Dry run: Skipping metadata update")
			}
		}

		os.Exit(0)
	}

	videoMeta.Filepath = path.Join(metadata.FootageDir, vodFiles[0])

	// no need to concat if VOD is already one whole file
	if len(vodFiles) > 1 {
		videoMeta.Filepath = path.Join(
			metadata.FootageDir,
			fmt.Sprintf("%s-fullvod.mkv", metadata.Date.String()),
		)

		if !dryRun {
			// check if full VOD already exists with expected duration
			concatVodExists := false
			concatVodProbe, err := scanner.ProbeSegment(videoMeta.Filepath)
			if err == nil {
				videoMeta.SizeBytes = concatVodProbe.Format.Size
				var totalLength float64 = 0

				for _, filename := range vodFiles {
					probe, err := scanner.ProbeSegment(path.Join(footageDir, filename))
					if err != nil { continue }
					totalLength += probe.Format.Duration
				}
				// full VOD may exist, but not be complete (interrupted concat)
				concatVodExists = math.Abs(concatVodProbe.Format.Duration - totalLength) < float64(0.1)
			}

			if concatVodExists {
				log.Print("Full VOD appears to already exist- uploading this file...")
			} else {
				// concatenate VOD segments into full VOD
				videoMeta.SizeBytes, err = vid.ConcatVideo(videoMeta, vodFiles, verbose)
				if err != nil {
					log.Fatalf("Failed to concatenate VOD segments: %v", err)
				}
			}
		} else {
			log.Print("Dry run: Skipping VOD concatenation")
		}
	}

	if !dryRun {
		// okay actually upload now!
		ytVideo, err := yt.UploadVideo(ctx, tokenSource, service, videoMeta, templates)
		if err != nil {
			log.Fatalf("Failed to upload video: %v", err)
		}
		if verbose {
			jsonString, err := json.MarshalIndent(ytVideo, "", "  ")
			if err != nil {
				log.Fatalf("Failed to marshal video data json: %v", err)
			}
			fmt.Println(string(jsonString))
		}
		log.Print("Video uploaded successfully!")

		// set the thumbnail
		log.Println("Uploading thumbnail...")
		if err = yt.UploadThumbnail(ctx, tokenSource, service, ytVideo.Id, thumbnail); err != nil {
			log.Printf("Failed to upload thumbnail: %v", err)
		}

		// update metadata to reflect VOD is uploaded
		metadata.UploadURL = yt.VIDEO_URL_BASE + ytVideo.Id
		err = scanner.WriteMetadata(directory, metadata)
		if err != nil {
			log.Fatalf("Failed to update metadata: %v", err)
		}

		// delete concatenated VOD after upload, unless specified otherwise
		// if len(vodFiles) == 1, the full VOD is the *only* VOD. do not delete this!!!
		if len(vodFiles) > 1 && !keepConcatVOD {
			if err = os.Remove(videoMeta.Filepath); err != nil {
				log.Fatalf("Failed to delete full VOD: %v", err)
			}
		}
	} else {
		log.Print("Dry run: Skipping video upload")
	}
}