package handlers

import (
	"crypto/rand"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"log"
	"net/http"
	"path/filepath"
	"strings"
	"thamanyah/cms/v2/internal/services"
	"thamanyah/cms/v2/internal/views"
	"time"
)

const (
	videoUploadPrefix = "videos"
	uploadURLExpiry   = 15 * time.Minute
	maxJSONBodySize   = 1 << 20 // 1 MiB
)

func NewVideo(w http.ResponseWriter, r *http.Request) {
	categories, err := services.DB.ListCategories(r.Context())
	if err != nil {
		log.Printf("Something Went Wrong Loading Categories: %s", err)
		http.Error(w, "Something Went Wrong Loading Categories", http.StatusInternalServerError)
		return
	}

	views.VideoUpload(categories).Render(r.Context(), w)
}

type presignRequest struct {
	FileName    string `json:"fileName"`
	ContentType string `json:"contentType"`
}

type presignResponse struct {
	UploadURL string `json:"uploadUrl"`
	Key       string `json:"key"`
}

func PresignVideoUpload(w http.ResponseWriter, r *http.Request) {
	r.Body = http.MaxBytesReader(w, r.Body, maxJSONBodySize)

	var req presignRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSONError(w, http.StatusBadRequest, "Invalid request.")
		return
	}

	if !strings.HasPrefix(req.ContentType, "video/") {
		writeJSONError(w, http.StatusUnprocessableEntity, fmt.Sprintf("Unsupported file type (%s). Please upload a video.", req.ContentType))
		return
	}

	filename, err := randomFilename(req.FileName)
	if err != nil {
		writeJSONError(w, http.StatusInternalServerError, "Could not prepare upload.")
		return
	}
	key := videoUploadPrefix + "/" + filename

	presignedURL, err := services.S3Client.GetPresignedURL(r.Context(), key, "video/mp4", time.Hour)
	if err != nil {
		writeJSONError(w, http.StatusInternalServerError, "Could not prepare upload.")
		return
	}

	w.Header().Set("Content-Type", "application/json")
	json.NewEncoder(w).Encode(presignResponse{UploadURL: presignedURL, Key: key})
}

type completeRequest struct {
	Title       string   `json:"title"`
	Description string   `json:"description"`
	Categories  []string `json:"categories"`
	Tags        string   `json:"tags"`
	FileName    string   `json:"fileName"`
	Key         string   `json:"key"`
}

func CompleteVideoUpload(w http.ResponseWriter, r *http.Request) {
	r.Body = http.MaxBytesReader(w, r.Body, maxJSONBodySize)

	var req completeRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		renderUploadError(w, r, "Invalid request.")
		return
	}

	title := strings.TrimSpace(req.Title)
	if title == "" {
		renderUploadError(w, r, "Title is required.")
		return
	}

	key := strings.TrimSpace(req.Key)
	if key == "" || !strings.HasPrefix(key, videoUploadPrefix+"/") {
		renderUploadError(w, r, "A video file is required.")
		return
	}

	categories := make([]string, 0, len(req.Categories))
	for _, category := range req.Categories {
		if category = strings.TrimSpace(category); category != "" {
			categories = append(categories, category)
		}
	}

	jobID, err := services.MediaConvertClient.QueueEncodingJob(r.Context(), key)
	if err != nil {
		log.Printf("Something Went Wrong On Creation Of Transcoding Job: %s", err)
		renderUploadError(w, r, "Something Went Wrong On Creation Of Transcoding Job")
		return
	}

	_, err = services.DB.CreateVideo(r.Context(), services.Video{
		Title:             title,
		Description:       strings.TrimSpace(req.Description),
		Categories:        categories,
		Tags:              strings.TrimSpace(req.Tags),
		FileName:          strings.TrimSpace(req.FileName),
		StorageKey:        key,
		MediaConvertJobID: jobID,
		Status:            "processing",
		SizeBytes:         60,
	})
	if err != nil {
		log.Printf("Something Went Wrong Saving The Video Record: %s", err)
		renderUploadError(w, r, "Something Went Wrong Saving The Video Record")
		return
	}

	views.VideoUploadSuccess(views.VideoMetadata{
		Title:       title,
		Description: strings.TrimSpace(req.Description),
		Categories:  categories,
		Tags:        strings.TrimSpace(req.Tags),
		FileName:    strings.TrimSpace(req.FileName),
		JobID:       jobID,
		StoredAs:    key,
		SizeBytes:   60,
	}).Render(r.Context(), w)
}

func writeJSONError(w http.ResponseWriter, status int, message string) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	json.NewEncoder(w).Encode(map[string]string{"error": message})
}

func renderUploadError(w http.ResponseWriter, r *http.Request, message string) {
	fmt.Println("Error Ocurred: " + message)
	w.WriteHeader(http.StatusUnprocessableEntity)
	views.VideoUploadError(message).Render(r.Context(), w)
}

func randomFilename(original string) (string, error) {
	ext := filepath.Ext(filepath.Base(original))
	buf := make([]byte, 16)
	if _, err := rand.Read(buf); err != nil {
		return "", err
	}
	return hex.EncodeToString(buf) + ext, nil
}