// Package handlers
package handlers

import (
	"encoding/json"
	"fmt"
	"net/http"
	"net/url"
	"time"

	"github.com/google/uuid"
	"github.com/minio/minio-go/v7"
	"github.com/minio/minio-go/v7/pkg/credentials"
)

const maxUploadSize = 10 << 20 // 10 MB

type UploadHandler struct {
	minioClient    *minio.Client
	bucket         string
	endpoint       string
	publicEndpoint string
}

func NewUploadHandler(endpoint, publicEndpoint, accessKey, secretKey, bucket string, useSSL bool) (*UploadHandler, error) {
	client, err := minio.New(endpoint, &minio.Options{
		Creds:  credentials.NewStaticV4(accessKey, secretKey, ""),
		Secure: useSSL,
	})
	if err != nil {
		return nil, err
	}

	return &UploadHandler{
		minioClient:    client,
		bucket:         bucket,
		endpoint:       endpoint,
		publicEndpoint: publicEndpoint,
	}, nil
}

type presignedURLRequest struct {
	ContentType string `json:"content_type"`
	MaxSizeMB   int    `json:"max_size_mb"`
}

type presignedURLResponse struct {
	UploadURL string            `json:"upload_url"`
	FileURL   string            `json:"file_url"`
	Fields    map[string]string `json:"fields"`
}

func (h *UploadHandler) UploadFile(w http.ResponseWriter, r *http.Request) {
	r.Body = http.MaxBytesReader(w, r.Body, maxUploadSize)
	if err := r.ParseMultipartForm(maxUploadSize); err != nil {
		writeError(w, http.StatusBadRequest, "file too large or invalid multipart", err)
		return
	}

	file, header, err := r.FormFile("file")
	if err != nil {
		writeError(w, http.StatusBadRequest, "file is required", err)
		return
	}
	defer file.Close()

	contentType := header.Header.Get("Content-Type")
	validContentTypes := map[string]bool{
		"image/jpeg": true, "image/png": true, "image/webp": true, "image/heic": true,
	}
	if !validContentTypes[contentType] {
		writeError(w, http.StatusBadRequest, "unsupported content type", nil)
		return
	}

	ext := ".jpg"
	switch contentType {
	case "image/png":
		ext = ".png"
	case "image/webp":
		ext = ".webp"
	case "image/heic":
		ext = ".heic"
	}
	objectName := "uploads/" + uuid.New().String() + ext

	_, err = h.minioClient.PutObject(r.Context(), h.bucket, objectName, file, header.Size,
		minio.PutObjectOptions{ContentType: contentType},
	)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to upload file", err)
		return
	}

	fileURL := fmt.Sprintf("%s/%s/%s", h.publicEndpoint, h.bucket, objectName)

	writeJSON(w, http.StatusOK, map[string]string{
		"file_url": fileURL,
	})
}

func (h *UploadHandler) PresignedURL(w http.ResponseWriter, r *http.Request) {
	var req presignedURLRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid request body", err)
		return
	}

	if req.MaxSizeMB <= 0 || req.MaxSizeMB > 50 {
		req.MaxSizeMB = 10
	}

	validContentTypes := map[string]bool{
		"image/jpeg": true, "image/png": true, "image/webp": true, "image/heic": true,
	}
	if !validContentTypes[req.ContentType] {
		writeError(w, http.StatusBadRequest, "unsupported content type", nil)
		return
	}

	fileID := uuid.New().String()
	ext := ".jpg"
	switch req.ContentType {
	case "image/png":
		ext = ".png"
	case "image/webp":
		ext = ".webp"
	case "image/heic":
		ext = ".heic"
	}
	objectName := "uploads/" + fileID + ext

	policy := minio.NewPostPolicy()
	policy.SetBucket(h.bucket)
	policy.SetKey(objectName)
	policy.SetExpires(time.Now().Add(15 * time.Minute))
	policy.SetContentType(req.ContentType)
	policy.SetContentLengthRange(1, int64(req.MaxSizeMB)*1024*1024)

	uploadURL, formData, err := h.minioClient.PresignedPostPolicy(r.Context(), policy)
	if err != nil {
		writeError(w, http.StatusInternalServerError, "failed to generate upload URL", err)
		return
	}

	// Replace internal endpoint (minio:9000) with public endpoint for browser uploads
	publicUploadURL := uploadURL
	uploadURLStr := h.publicEndpoint + uploadURL.Path + "?" + uploadURL.RawQuery
	if parsed, err := url.Parse(uploadURLStr); err == nil {
		publicUploadURL = parsed
	}

	fileURL := h.publicEndpoint + "/" + h.bucket + "/" + objectName

	writeJSON(w, http.StatusOK, presignedURLResponse{
		UploadURL: publicUploadURL.String(),
		FileURL:   fileURL,
		Fields:    formData,
	})
}