// Copyright (c) 2025 Nikolai Papin
//
// This file is part of Easywish
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
// the GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.

package services

import (
	"context"
	"easywish/config"
	minioclient "easywish/internal/minioClient"
	errs "easywish/internal/errors"
	"easywish/internal/utils"
	"fmt"
	"net/url"
	"time"

	"github.com/google/uuid"
	"github.com/minio/minio-go/v7"
	"go.uber.org/zap"
)

type S3Service interface {
	CreateAvatarUrl() (*string, *map[string]string, error)
	CreateImageUrl() (*string, *map[string]string, error)
	SaveUpload(uploadID string, bucket string) (*string, error)

	GetLocalizedFileUrl(key string, bucket string) url.URL
}

type s3ServiceImpl struct {
	minio *minio.Client
	log   *zap.Logger

	avatarPolicy minio.PostPolicy
	imagePolicy  minio.PostPolicy
}

func NewS3Service(_minio *minio.Client, _log *zap.Logger) S3Service {
	service := s3ServiceImpl{
		minio: _minio,
		log:   _log,
	}

	avatarPolicy := minio.NewPostPolicy()
	imagePolicy := minio.NewPostPolicy()

	// At the moment the parameters match for both policies but this may
	// change with introduction of new policies
	for _, policy := range [...]*minio.PostPolicy{avatarPolicy, imagePolicy} {
		if err := policy.SetBucket(minioclient.Buckets["uploads"]); err != nil {
			panic("Failed to set bucket for policy: " + err.Error())
		}

		if err := policy.SetExpires(time.Now().UTC().Add(10 * time.Minute)); err != nil {
			panic("Failed to set expiration time for policy: " + err.Error())
		}

		if err := policy.SetContentTypeStartsWith("image/"); err != nil {
			panic("Failed to set allowed content types for the policy: " + err.Error())
		}

		if err := policy.SetContentLengthRange(1, 512*1024); err != nil {
			panic("Failed to set allowed content length range for the policy: " + err.Error())
		}
	}

	service.imagePolicy = *imagePolicy
	service.avatarPolicy = *avatarPolicy

	return &service
}

func (s *s3ServiceImpl) genUrl(policy minio.PostPolicy, prefix string) (*string, *map[string]string, error) {

	object := prefix + uuid.New().String()

	if err := policy.SetKey(object); err != nil {
		s.log.Error(
			"Failed to set random key for presigned url",
			zap.Error(err))
		return nil, nil, err
	}

	url, formData, err := s.minio.PresignedPostPolicy(context.Background(), &policy)
	if err != nil {
		s.log.Error(
			"Failed to generate presigned url",
			zap.String("object", object),
			zap.Error(err))
		return nil, nil, err
	}

	convertedUrl, err := utils.LocalizeS3Url(url.String())
	if err != nil {
		s.log.Error(
			"Failed to localize object URL to user-accessible format",
			zap.String("url", url.String()),
			zap.Error(err))
		return nil, nil, err
	}

	return utils.NewPointer(convertedUrl.String()), &formData, nil
}

func (s *s3ServiceImpl) CreateAvatarUrl() (*string, *map[string]string, error) {
	return s.genUrl(s.avatarPolicy, "avatar-")
}

func (s *s3ServiceImpl) CreateImageUrl() (*string, *map[string]string, error) {
	return s.genUrl(s.imagePolicy, "image-")
}

func (s *s3ServiceImpl) SaveUpload(uploadID string, bucketAlias string) (*string, error) {
	sourceBucket := minioclient.Buckets["uploads"]
	bucket := minioclient.Buckets[bucketAlias]
	newObjectKey := uuid.New().String()
 
	_, err := s.minio.StatObject(context.Background(), sourceBucket, uploadID, minio.StatObjectOptions{})
	if err != nil {
		if minio.ToErrorResponse(err).Code == minio.NoSuchKey {
			return nil, errs.ErrFileNotFound
		}
	}
	_, err = s.minio.CopyObject(context.Background(), minio.CopyDestOptions{
		Bucket: bucket,
		Object: newObjectKey,
	}, minio.CopySrcOptions{
		Bucket: sourceBucket,
		Object: uploadID,
	})
	if err != nil {
		s.log.Error(
			"Failed to copy object to new bucket",
			zap.String("sourceBucket", sourceBucket),
			zap.String("uploadID", uploadID),
			zap.String("destinationBucket", bucket),
			zap.String("newObjectKey", newObjectKey),
			zap.Error(err))
		return nil, err
	}

	err = s.minio.RemoveObject(context.Background(), sourceBucket, uploadID, minio.RemoveObjectOptions{})
	if err != nil {
		s.log.Error(
			"Failed to remove original object from uploads bucket",
			zap.String("sourceBucket", sourceBucket),
			zap.String("uploadID", uploadID),
			zap.Error(err))
		return nil, err
	}

	return &newObjectKey, nil
}

func (s *s3ServiceImpl) GetLocalizedFileUrl(key string, bucketAlias string) url.URL {
	cfg := config.GetConfig()

	return url.URL{
		Scheme: "http",
		Host: fmt.Sprintf("%s:%d", cfg.Hostname, cfg.Port),
		Path: fmt.Sprintf("/s3/%s/%s", minioclient.Buckets[bucketAlias], key),
	}
}