package web

import (
	"errors"
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"strconv"
	"strings"

	"gitea.kazu634.com/kazu634/tver/internal/store"
	"github.com/jackc/pgx/v5"
)

const libraryLimit = 100

type libraryItemView struct {
	ID                               int64
	ThumbnailURL, SeriesTitle, Title string
	BroadcasterName, DurationText    string
	FileSizeText, FinishedAtText     string
}

type libraryView struct {
	Items []libraryItemView
}

type videoView struct {
	libraryItemView
	VideoURL string
}

func (s *server) libraryPage(w http.ResponseWriter, r *http.Request) {
	jobs, err := s.jobs.ListSucceededJobs(r.Context(), libraryLimit)
	if err != nil {
		s.logger.Printf("ライブラリの取得に失敗: %v", err)
		http.Error(w, "ライブラリを取得できませんでした", http.StatusInternalServerError)
		return
	}
	view := libraryView{Items: make([]libraryItemView, 0, len(jobs))}
	for _, job := range jobs {
		view.Items = append(view.Items, s.libraryItem(job))
	}
	s.render(w, "layout", page{Title: "ライブラリ", Library: &view})
}

func (s *server) videoPage(w http.ResponseWriter, r *http.Request) {
	job, ok := s.succeededJob(w, r)
	if !ok {
		return
	}
	item := s.libraryItem(job)
	s.render(w, "layout", page{Title: job.SeriesTitle + " " + job.Title,
		Video: &videoView{libraryItemView: item, VideoURL: "/videos/" + strconv.FormatInt(job.ID, 10)}})
}

func (s *server) libraryItem(job store.Job) libraryItemView {
	item := libraryItemView{ID: job.ID, ThumbnailURL: "https://statics.tver.jp" + job.ThumbnailPath,
		SeriesTitle: job.SeriesTitle, Title: job.Title, BroadcasterName: job.BroadcasterName,
		DurationText: fmt.Sprintf("%d分", durationMinutes(int64(job.DurationSeconds)))}
	if job.FileSizeBytes != nil {
		item.FileSizeText = formatBytes(float64(*job.FileSizeBytes))
	}
	if job.FinishedAt != nil {
		item.FinishedAtText = job.FinishedAt.In(s.zone).Format("2006-01-02 15:04 MST")
	}
	return item
}

func (s *server) serveVideo(w http.ResponseWriter, r *http.Request) {
	job, ok := s.succeededJob(w, r)
	if !ok || job.FilePath == nil {
		if ok {
			http.NotFound(w, r)
		}
		return
	}
	path, err := secureVideoPath(s.videoDir, *job.FilePath, true)
	if err != nil {
		http.NotFound(w, r)
		return
	}
	file, err := os.Open(path)
	if err != nil {
		http.NotFound(w, r)
		return
	}
	defer file.Close()
	info, err := file.Stat()
	if err != nil || !info.Mode().IsRegular() {
		http.NotFound(w, r)
		return
	}
	w.Header().Set("Content-Type", "video/mp4")
	http.ServeContent(w, r, filepath.Base(path), info.ModTime(), file)
}

func (s *server) deleteVideo(w http.ResponseWriter, r *http.Request) {
	job, ok := s.succeededJob(w, r)
	if !ok {
		return
	}
	if job.FilePath != nil {
		path, err := secureVideoPath(s.videoDir, *job.FilePath, false)
		if err != nil {
			http.Error(w, "動画ファイルの場所が不正です", http.StatusConflict)
			return
		}
		if err := os.Remove(path); err != nil && !errors.Is(err, os.ErrNotExist) {
			s.logger.Printf("動画ファイルの削除に失敗: %v", err)
			http.Error(w, "動画ファイルを削除できませんでした", http.StatusInternalServerError)
			return
		}
	}
	if err := s.jobs.DeleteSucceededJob(r.Context(), job.ID); err != nil {
		s.logger.Printf("動画の記録削除に失敗: %v", err)
		http.Error(w, "動画の記録を削除できませんでした", http.StatusInternalServerError)
		return
	}
	http.Redirect(w, r, "/library", http.StatusSeeOther)
}

func (s *server) succeededJob(w http.ResponseWriter, r *http.Request) (store.Job, bool) {
	id, err := strconv.ParseInt(r.PathValue("id"), 10, 64)
	if err != nil || id <= 0 {
		http.NotFound(w, r)
		return store.Job{}, false
	}
	job, err := s.jobs.GetSucceededJob(r.Context(), id)
	if errors.Is(err, pgx.ErrNoRows) {
		http.NotFound(w, r)
		return store.Job{}, false
	}
	if err != nil {
		s.logger.Printf("完了ジョブの取得に失敗: %v", err)
		http.Error(w, "動画を取得できませんでした", http.StatusInternalServerError)
		return store.Job{}, false
	}
	return job, true
}

func secureVideoPath(root, relative string, mustExist bool) (string, error) {
	if relative == "" || filepath.IsAbs(relative) {
		return "", errors.New("video path must be relative")
	}
	clean := filepath.Clean(relative)
	if clean == "." || clean == ".." || strings.HasPrefix(clean, ".."+string(filepath.Separator)) {
		return "", errors.New("video path leaves root")
	}
	rootAbs, err := filepath.Abs(root)
	if err != nil {
		return "", err
	}
	rootReal, err := filepath.EvalSymlinks(rootAbs)
	if err != nil {
		return "", err
	}
	candidate := filepath.Join(rootAbs, clean)
	if err := insideRoot(rootAbs, candidate); err != nil {
		return "", err
	}
	resolved, err := filepath.EvalSymlinks(candidate)
	if err == nil {
		if err := insideRoot(rootReal, resolved); err != nil {
			return "", err
		}
		return candidate, nil
	}
	if mustExist || !errors.Is(err, os.ErrNotExist) {
		return "", err
	}
	ancestor := filepath.Dir(candidate)
	for {
		resolvedAncestor, evalErr := filepath.EvalSymlinks(ancestor)
		if evalErr == nil {
			if err := insideRoot(rootReal, resolvedAncestor); err != nil {
				return "", err
			}
			return candidate, nil
		}
		if !errors.Is(evalErr, os.ErrNotExist) || ancestor == rootAbs {
			return "", evalErr
		}
		ancestor = filepath.Dir(ancestor)
	}
}

func insideRoot(root, path string) error {
	rel, err := filepath.Rel(root, path)
	if err != nil || rel == ".." || strings.HasPrefix(rel, ".."+string(filepath.Separator)) {
		return errors.New("path leaves video root")
	}
	return nil
}