package server

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"net/url"
	"os"
	"path"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/gin-gonic/gin"
	"github.com/pelletier/go-toml/v2"

	"arimelody.space/melody-vod-manager/public"
	"arimelody.space/melody-vod-manager/scanner"
	"arimelody.space/melody-vod-manager/templates"
)

type (
	VODGoogleConfig struct {
		ApiKey			string
		ClientID		string
		ClientSecret	string
	}

	VODServerConfig struct {
		Host string
		Port int16
		VODDirectory string
		TemplateDirectory string
	}

	VODServer struct {
		config VODServerConfig
		google VODGoogleConfig
		googleToken	string

		textTemplates *templates.TextTemplates

		started sync.Mutex
		logger *slog.Logger
		router *gin.Engine
	}
)

func New(config VODServerConfig, google VODGoogleConfig, textTemplates *templates.TextTemplates) (*VODServer, error) {
	server := &VODServer{
		started: sync.Mutex{},
		logger: slog.Default().WithGroup("VOD-MANAGER"),
		router: gin.Default(),
	}

	server.config = config
	server.google = google
	server.textTemplates = textTemplates

	return server, nil
}

func (srv *VODServer) Run(ctx context.Context) error {
	if !srv.started.TryLock() {
		return errors.New("server already started")
	}
	defer srv.started.Unlock()

	failed := make(chan error)

	go func() {
		err := srv.start(ctx)
		if !errors.Is(err, context.Canceled) {
			failed <- err
		}
	}()

	select {
	case err := <-failed:
		return err
	case <-ctx.Done():
		srv.stop(ctx)
		return context.Canceled
	}
}

func (srv *VODServer) handleGetVOD(ctx *gin.Context, vodDir string, metadata *scanner.Metadata) {
	if ctx.Request.Header.Get("Accept") == "application/json" {
		ctx.JSON(http.StatusOK, metadata)
		return
	}

	type (
		VODFootageBlock struct {
			Name		string
			Size		string
			SizeBytes	int64
		}

		VOD struct {
			Title					string
			Part					uint
			Date					time.Time
			TitleFormatted			string
			Tags					[]string
			Category				*scanner.Category
			DescriptionFormatted	string
			Uploaded				bool
			FootageDir				string
			Footage					[]VODFootageBlock
			Directory				string
		}
	)

	var err error

	textTemplateData := templates.TextTemplateData{
		Title: metadata.Title,
		Part: uint(metadata.Part),
		Date: metadata.Date.AsTime(time.UTC),
		Category: metadata.Category,
	}

	titleFormatted := bytes.Buffer{}
	err = srv.textTemplates.Title.Execute(&titleFormatted, textTemplateData)
	if err != nil {
		srv.logger.Error("Failed to format VOD title:", "dir", vodDir, "err", err)
		ctx.String(
			http.StatusInternalServerError,
			http.StatusText(http.StatusInternalServerError),
		)
		return
	}

	descriptionFormatted := bytes.Buffer{}
	err = srv.textTemplates.Description.Execute(&descriptionFormatted, textTemplateData)
	if err != nil {
		srv.logger.Error("Failed to format VOD description:", "dir", vodDir, "err", err)
		ctx.String(
			http.StatusInternalServerError,
			http.StatusText(http.StatusInternalServerError),
		)
		return
	}

	vod := VOD{
		Title: metadata.Title,
		Part: uint(metadata.Part),
		Date: metadata.Date.AsTime(time.UTC),
		TitleFormatted: titleFormatted.String(),
		Tags: metadata.Tags,
		Category: metadata.Category,
		DescriptionFormatted: descriptionFormatted.String(), 
		Uploaded: metadata.Uploaded,
		FootageDir: metadata.FootageDir,
		Footage: []VODFootageBlock{},
		Directory: strings.TrimPrefix(vodDir[:strings.LastIndex(vodDir, "/")], srv.config.VODDirectory),
	}
	footageDir := path.Join(vodDir, metadata.FootageDir)
	files, err := os.ReadDir(footageDir)
	if err != nil {
		srv.logger.Error("Failed to read footage directory:", "dir", footageDir, "err", err)
		ctx.String(
			http.StatusInternalServerError,
			http.StatusText(http.StatusInternalServerError),
		)
	}
	for _, file := range files {
		if file.IsDir() || !strings.HasSuffix(file.Name(), "mkv") { continue }
		filePath := path.Join(vodDir, metadata.FootageDir, file.Name())
		stat, err := os.Stat(filePath)
		if err != nil {
			srv.logger.Error("Failed to stat file:", "path", filePath, "err", err)
			ctx.String(
				http.StatusInternalServerError,
				http.StatusText(http.StatusInternalServerError),
			)
		}

		vod.Footage = append(vod.Footage, VODFootageBlock{
			Name: file.Name(),
			Size: scanner.FileSizeString(stat.Size()),
			SizeBytes: stat.Size(),
		})
	}

	if err := templates.VODTemplate.Execute(ctx.Writer, vod); err != nil {
		srv.logger.Error("Failed to render VOD template:", "err", err)
		ctx.String(
			http.StatusInternalServerError,
			http.StatusText(http.StatusInternalServerError),
		)
	}
}

func (srv *VODServer) handleInitVODDirectory (ctx *gin.Context, vodDir string) {
	srv.logger.Debug("Initialising VOD directory:", "dir", vodDir)

	metadata := scanner.DefaultMetadata()
	err := scanner.WriteMetadata(vodDir, metadata)
	if err != nil {
		srv.logger.Error("Failed to initialise VOD directory:", "dir", vodDir, "err", err)
		ctx.String(http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError))
		return
	}

	ctx.Redirect(
		http.StatusFound,
		fmt.Sprintf("/vods%s", strings.TrimPrefix(vodDir, srv.config.VODDirectory)),
	)
}

func (srv *VODServer) handleListVODs(ctx *gin.Context, queryDir string) {
	stat, err := os.Stat(queryDir)

	if !stat.IsDir() {
		http.ServeFile(ctx.Writer, ctx.Request, queryDir)
		return
	}

	if ctx.Query("init") == "true" {
		srv.handleInitVODDirectory(ctx, queryDir)
		return
	}

	metadata, err := scanner.ReadMetadata(queryDir)
	if err != nil && !os.IsNotExist(err) {
		srv.logger.Error("Failed to read metadata:", "err", err)
		ctx.Status(http.StatusInternalServerError)
		return
	}
	if metadata != nil {
		srv.handleGetVOD(ctx, queryDir, metadata)
		return
	}

	dirs, err := os.ReadDir(queryDir)
	if err != nil {
		srv.logger.Error("Failed to read directory:", "dir", queryDir, "err", err)
		ctx.Status(http.StatusInternalServerError)
		return
	}

	type (
		VODListItem struct {
			Title string `json:"title"`
			Path string `json:"path"`
		}

		FileItem struct {
			Name string `json:"name"`
			Size string `json:"-"`
			SizeBytes int64 `json:"size"`
		}

		ListVODsResponse struct {
			VODs []VODListItem `json:"vods"`
			Directories []string `json:"directories"`
			Files []FileItem `json:"files"`
		}

		ListVODsHTMLResponse struct {
			ListVODsResponse
			Directory string
		}
	)

	res := ListVODsResponse{
		VODs: []VODListItem{},
		Directories: []string{},
		Files: []FileItem{},
	}
	for _, dir := range dirs {
		if dir.IsDir() {
			fullPath := path.Join(queryDir, dir.Name())
			metadata, err := scanner.ReadMetadata(fullPath)
			if err != nil && !os.IsNotExist(err) {
				slog.Error("Failed to read metadata:", "dir", fullPath, "err", err)
				// soft fail (list as directory)
			}
			if metadata != nil {
				titleFormatted := &bytes.Buffer{}
				if err := srv.textTemplates.Title.Execute(titleFormatted, templates.TextTemplateData{
					Title: metadata.Title,
					Part: uint(metadata.Part),
					Date: metadata.Date.AsTime(time.UTC),
					Category: metadata.Category,
				}); err != nil {
					srv.logger.Error("Failed to format VOD title:", "vodPath", fullPath, "err", err)
					continue
				}

				res.VODs = append(res.VODs, VODListItem{
					Title: strings.TrimSpace(titleFormatted.String()),
					Path: dir.Name(),
				})
			} else {
				res.Directories = append(res.Directories, dir.Name())
			}
		} else {
			filePath := path.Join(queryDir, dir.Name())
			stat, err := os.Stat(filePath)
			if err != nil {
				srv.logger.Error("Failed to stat file:", "path", filePath, "err", err)
				continue
			}
			res.Files = append(res.Files, FileItem{
				Name: stat.Name(),
				Size: scanner.FileSizeString(stat.Size()),
				SizeBytes: stat.Size(),
			})
		}
	}

	ctx.Header("cache-control", "max-age=0")
	if ctx.GetHeader("accept") == "application/json" {
		ctx.JSON(http.StatusOK, res)
	} else {
		if err := templates.VODListTemplate.Execute(ctx.Writer, ListVODsHTMLResponse{
			ListVODsResponse: res,
			Directory: strings.TrimPrefix(queryDir, srv.config.VODDirectory),
		}); err != nil {
			srv.logger.Error("Failed to render VOD list template:", "err", err)
			ctx.String(http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError))
		}
	}
}

func (srv *VODServer) handleUpdateVOD(ctx *gin.Context, vodDir string) {
	metadata, err := scanner.ReadMetadata(vodDir)
	if err != nil {
		if os.IsNotExist(err) {
			http.NotFound(ctx.Writer, ctx.Request)
			return
		}
		ctx.String(http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError))
		return
	}

	if title := ctx.PostForm("title"); title != "" { metadata.Title = title }
	if part, err := strconv.Atoi(ctx.PostForm("part")); err == nil && part > 0 { metadata.Part = part }
	if date, err := time.Parse("2006-01-02", ctx.PostForm("date")); err == nil { metadata.Date = toml.LocalDate{
		Year: date.Year(), Month: int(date.Month()), Day: date.Day(),
	} }
	if ctx.PostForm("category-enabled") == "on" {
		metadata.Category = &scanner.Category{}
		if categoryName := ctx.PostForm("category-name"); categoryName != "" { metadata.Category.Name = categoryName }
		if categoryType := ctx.PostForm("category-type"); categoryType != "" { metadata.Category.Type = categoryType }
		if categoryUrl := ctx.PostForm("category-url"); categoryUrl != "" { metadata.Category.Url = categoryUrl }
	} else {
		metadata.Category = nil
	}

	err = scanner.WriteMetadata(vodDir, metadata)
	if err != nil {
		srv.logger.Error("Failed to write VOD metadata:", "dir", vodDir, "err", err)
		ctx.String(http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError))
		return
	}

	ctx.Redirect(
		http.StatusFound,
		fmt.Sprintf("/vods%s", strings.TrimPrefix(vodDir, srv.config.VODDirectory)),
	)
}

func (srv *VODServer) start(ctx context.Context) error {
	srv.logger.Info("Starting server...")

	srv.router.GET("/_health", func(ctx *gin.Context) {
		ctx.String(http.StatusOK, http.StatusText(http.StatusOK))
	})

	srv.router.GET("/", func(ctx *gin.Context) {
		if err := templates.IndexTemplate.Execute(ctx.Writer, nil); err != nil {
			ctx.String(http.StatusInternalServerError, http.StatusText(http.StatusInternalServerError))
		}
	})

	srv.router.GET("/vods", func(ctx *gin.Context) {
		srv.handleListVODs(ctx, srv.config.VODDirectory)
	})
	srv.router.GET("/vods/*path", func(ctx *gin.Context) {
		srv.handleListVODs(ctx, path.Join(srv.config.VODDirectory, ctx.Param("path")))
	})
	srv.router.POST("/vods/*path", func(ctx *gin.Context) {
		srv.handleUpdateVOD(ctx, path.Join(srv.config.VODDirectory, ctx.Param("path")))
	})

	srv.router.GET("/sse", func(ctx *gin.Context) {
		queryEscape, err := url.PathUnescape(ctx.Query("vod"))
		if err != nil {
			srv.logger.Error("Failed to parse SSE query string:", "err", err)
			ctx.String(http.StatusBadRequest, http.StatusText(http.StatusBadRequest))
			return
		}

		vodDir := path.Join(srv.config.VODDirectory, queryEscape)
		srv.logger.Debug("SSE connection:", "vod", vodDir)

		ticker := time.NewTicker(1 * time.Second)
		defer ticker.Stop()

		ctx.Stream(func(w io.Writer) bool {
			<-ticker.C
			ctx.SSEvent("", gin.H{
				"state": "uploading",
				"progress": "13.37",
			})
			return true
		})
	})

	srv.router.GET("/templates/title", func(ctx *gin.Context) {
		tmpl := templates.DefaultTitleTemplate
		var titlePath = path.Join(srv.config.TemplateDirectory, "title.txt")
		if titleFile, err := os.ReadFile(titlePath); err == nil {
			ctx.String(http.StatusOK, string(titleFile))
			return
		}
		ctx.String(http.StatusOK, tmpl)
	})
	srv.router.GET("/templates/description", func(ctx *gin.Context) {
		tmpl := templates.DefaultDescriptionTemplate
		var descriptionPath = path.Join(srv.config.TemplateDirectory, "description.txt")
		if descriptionFile, err := os.ReadFile(descriptionPath); err == nil {
			ctx.String(http.StatusOK, string(descriptionFile))
			return
		}
		ctx.String(http.StatusOK, tmpl)
	})
	srv.router.GET("/templates/tags", func(ctx *gin.Context) {
		var tagsPath = path.Join(srv.config.TemplateDirectory, "tags.txt")
		ctx.Header("content-type", "application/json")
		if tagsFile, err := os.ReadFile(tagsPath); err == nil {
			tags := strings.Split(strings.TrimSuffix(string(tagsFile), "\n"), "\n")
			res := strings.Builder{}
			res.WriteRune('[')
			for i, tag := range tags {
				fmt.Fprintf(&res, "\"%s\"", tag)
				if i < len(tags) - 1 { res.WriteString(", ") }
			}
			res.WriteRune(']')
			ctx.String(http.StatusOK, res.String())
			return
		}
		ctx.String(http.StatusOK, "[]")
	})

	srv.router.GET("/style/*path", func(ctx *gin.Context) {
		path := strings.TrimPrefix(ctx.Request.URL.Path, "/")
		http.ServeFileFS(ctx.Writer, ctx.Request, public.StyleFS, path)
	})

	srv.router.GET("/script/*path", func(ctx *gin.Context) {
		path := strings.TrimPrefix(ctx.Request.URL.Path, "/")
		http.ServeFileFS(ctx.Writer, ctx.Request, public.ScriptFS, path)
	})

	failed := make(chan error)

	go func() {
		srv.logger.Info("Server online.", "host", srv.config.Host, "port", srv.config.Port)
		failed <- srv.router.Run(fmt.Sprintf(":%d", srv.config.Port))
	}()

	select {
	case err := <-failed:
		return err
	case <-ctx.Done():
		return context.Canceled
	}
}

func (srv *VODServer) stop(_ context.Context) {
	srv.logger.Info("Shutting down...")
}