package handlers

import (
	"bytes"
	"fmt"
	"io"
	"mime/multipart"
	"net/http"
	"path/filepath"
	"strings"
	"time"

	"github.com/aws/aws-sdk-go-v2/service/s3"
	"github.com/gin-gonic/gin"
	"github.com/google/uuid"
)

// MediaHandler uploads media to Cloudflare R2. If s3Client is provided, it uses
// the S3-compatible API. Otherwise, it falls back to Cloudflare R2 HTTP API
// using account ID + API token from the config.
type MediaHandler struct {
	s3Client     *s3.Client
	useS3        bool
	accountID    string
	apiToken     string
	bucket       string
	videoBucket  string
	publicDomain string
	videoDomain  string
}

func NewMediaHandler(s3Client *s3.Client, accountID string, apiToken string, bucket string, videoBucket string, publicDomain string, videoDomain string) *MediaHandler {
	return &MediaHandler{
		s3Client:     s3Client,
		useS3:        s3Client != nil,
		accountID:    accountID,
		apiToken:     apiToken,
		bucket:       bucket,
		videoBucket:  videoBucket,
		publicDomain: publicDomain,
		videoDomain:  videoDomain,
	}
}

func (h *MediaHandler) Upload(c *gin.Context) {
	fileHeader, err := c.FormFile("media")
	if err != nil {
		fileHeader, err = c.FormFile("image")
		if err != nil {
			c.JSON(http.StatusBadRequest, gin.H{"error": "No media file found"})
			return
		}
	}

	mediaType := c.PostForm("type")
	if mediaType == "" {
		if strings.HasPrefix(fileHeader.Header.Get("Content-Type"), "video/") {
			mediaType = "video"
		} else {
			mediaType = "image"
		}
	}

	ext := filepath.Ext(fileHeader.Filename)
	if ext == "" {
		if mediaType == "video" {
			ext = ".mp4"
		} else {
			ext = ".jpg"
		}
	}

	userID := c.GetString("user_id")
	if userID == "" {
		userID = "anon"
	}

	objectKey := fmt.Sprintf("uploads/%s/%s%s", userID, uuid.New().String(), ext)

	targetBucket := h.bucket
	targetDomain := h.publicDomain
	if mediaType == "video" {
		if h.videoBucket != "" {
			targetBucket = h.videoBucket
		}
		if h.videoDomain != "" {
			targetDomain = h.videoDomain
		}
	}

	var publicURL string
	if h.useS3 {
		publicURL, err = h.putObjectS3(c, fileHeader, targetBucket, objectKey, targetDomain)
	} else {
		publicURL, err = h.putObjectR2API(c, fileHeader, targetBucket, objectKey, targetDomain)
	}
	if err != nil {
		c.JSON(http.StatusInternalServerError, gin.H{"error": fmt.Sprintf("Failed to upload media: %v", err)})
		return
	}

	c.JSON(http.StatusOK, gin.H{
		"url":       publicURL,
		"publicUrl": publicURL,
		"signedUrl": publicURL,
		"fileName":  objectKey,
		"file_name": objectKey,
		"fileSize":  fileHeader.Size,
		"file_size": fileHeader.Size,
		"type":      mediaType,
	})
}

func (h *MediaHandler) putObjectS3(c *gin.Context, fileHeader *multipart.FileHeader, bucket string, key string, publicDomain string) (string, error) {
	src, err := fileHeader.Open()
	if err != nil {
		return "", err
	}
	defer src.Close()

	ctx := c.Request.Context()
	_, err = h.s3Client.PutObject(ctx, &s3.PutObjectInput{
		Bucket:      &bucket,
		Key:         &key,
		Body:        src,
		ContentType: &[]string{fileHeader.Header.Get("Content-Type")}[0],
	})
	if err != nil {
		return "", err
	}

	if publicDomain != "" {
		return fmt.Sprintf("https://%s/%s", publicDomain, key), nil
	}

	// Fallback to path (relative); AssetService can sign it later.
	return key, nil
}

func (h *MediaHandler) putObjectR2API(c *gin.Context, fileHeader *multipart.FileHeader, bucket string, key string, publicDomain string) (string, error) {
	if h.accountID == "" || h.apiToken == "" {
		return "", fmt.Errorf("R2 API credentials missing")
	}

	src, err := fileHeader.Open()
	if err != nil {
		return "", err
	}
	defer src.Close()

	fileBytes, err := io.ReadAll(src)
	if err != nil {
		return "", err
	}

	endpoint := fmt.Sprintf("https://api.cloudflare.com/client/v4/accounts/%s/r2/buckets/%s/objects/%s",
		h.accountID, bucket, key)

	req, err := http.NewRequestWithContext(c.Request.Context(), "PUT", endpoint, bytes.NewReader(fileBytes))
	if err != nil {
		return "", err
	}

	req.Header.Set("Authorization", "Bearer "+h.apiToken)
	req.Header.Set("Content-Type", fileHeader.Header.Get("Content-Type"))

	client := &http.Client{Timeout: 60 * time.Second}
	resp, err := client.Do(req)
	if err != nil {
		return "", err
	}
	defer resp.Body.Close()

	body, _ := io.ReadAll(resp.Body)
	if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusCreated {
		return "", fmt.Errorf("R2 upload failed (%d): %s", resp.StatusCode, string(body))
	}

	if publicDomain != "" {
		return fmt.Sprintf("https://%s/%s", publicDomain, key), nil
	}

	return fmt.Sprintf("https://%s.r2.cloudflarestorage.com/%s/%s", h.accountID, bucket, key), nil
}