package storage

import (
	"context"
	"errors"
	"fmt"
	"io"
	"strings"
	"time"

	"github.com/aws/aws-sdk-go-v2/aws"
	awsconfig "github.com/aws/aws-sdk-go-v2/config"
	"github.com/aws/aws-sdk-go-v2/credentials"
	"github.com/aws/aws-sdk-go-v2/service/s3"
	"github.com/aws/aws-sdk-go-v2/service/s3/types"
	"github.com/aws/smithy-go"

	"shared-album/internal/config"
)

type Client struct {
	s3         *s3.Client
	presign    *s3.PresignClient
	bucket     string
	presignTTL time.Duration
}

func New(ctx context.Context, cfg config.S3) (*Client, error) {
	awsCfg, err := awsconfig.LoadDefaultConfig(ctx,
		awsconfig.WithRegion(cfg.Region),
		awsconfig.WithCredentialsProvider(credentials.NewStaticCredentialsProvider(
			cfg.AccessKey, cfg.SecretKey, "",
		)),
	)
	if err != nil {
		return nil, fmt.Errorf("load aws config: %w", err)
	}

	client := s3.NewFromConfig(awsCfg, func(o *s3.Options) {
		o.BaseEndpoint = aws.String(cfg.Endpoint)
		o.UsePathStyle = cfg.UsePathStyle
	})

	return &Client{
		s3:         client,
		presign:    s3.NewPresignClient(client),
		bucket:     cfg.Bucket,
		presignTTL: cfg.PresignTTL,
	}, nil
}

func (c *Client) Bucket() string { return c.bucket }

func (c *Client) EnsureBucket(ctx context.Context) error {
	_, err := c.s3.HeadBucket(ctx, &s3.HeadBucketInput{Bucket: aws.String(c.bucket)})
	if err == nil {
		return nil
	}
	var nf *types.NotFound
	if !errors.As(err, &nf) && !isNoSuchBucket(err) {
		return fmt.Errorf("head bucket: %w", err)
	}
	if _, err := c.s3.CreateBucket(ctx, &s3.CreateBucketInput{Bucket: aws.String(c.bucket)}); err != nil {
		return fmt.Errorf("create bucket: %w", err)
	}
	return nil
}

func (c *Client) Ping(ctx context.Context) error {
	_, err := c.s3.HeadBucket(ctx, &s3.HeadBucketInput{Bucket: aws.String(c.bucket)})
	return err
}

func (c *Client) Put(ctx context.Context, key string, body io.Reader, size int64, contentType string) error {
	in := &s3.PutObjectInput{
		Bucket:      aws.String(c.bucket),
		Key:         aws.String(key),
		Body:        body,
		ContentType: aws.String(contentType),
	}
	if size >= 0 {
		in.ContentLength = aws.Int64(size)
	}
	if _, err := c.s3.PutObject(ctx, in); err != nil {
		return fmt.Errorf("put object %s: %w", key, err)
	}
	return nil
}

func (c *Client) Delete(ctx context.Context, keys ...string) error {
	if len(keys) == 0 {
		return nil
	}
	objs := make([]types.ObjectIdentifier, 0, len(keys))
	for _, k := range keys {
		objs = append(objs, types.ObjectIdentifier{Key: aws.String(k)})
	}
	if _, err := c.s3.DeleteObjects(ctx, &s3.DeleteObjectsInput{
		Bucket: aws.String(c.bucket),
		Delete: &types.Delete{Objects: objs, Quiet: aws.Bool(true)},
	}); err != nil {
		return fmt.Errorf("delete objects: %w", err)
	}
	return nil
}

func (c *Client) DeletePrefix(ctx context.Context, prefix string) error {
	var keys []string
	paginator := s3.NewListObjectsV2Paginator(c.s3, &s3.ListObjectsV2Input{
		Bucket: aws.String(c.bucket),
		Prefix: aws.String(prefix),
	})
	for paginator.HasMorePages() {
		page, err := paginator.NextPage(ctx)
		if err != nil {
			return fmt.Errorf("list objects: %w", err)
		}
		for _, o := range page.Contents {
			keys = append(keys, aws.ToString(o.Key))
		}
	}
	return c.Delete(ctx, keys...)
}

func (c *Client) PresignGet(ctx context.Context, key string) (string, error) {
	out, err := c.presign.PresignGetObject(ctx, &s3.GetObjectInput{
		Bucket: aws.String(c.bucket),
		Key:    aws.String(key),
	}, s3.WithPresignExpires(c.presignTTL))
	if err != nil {
		return "", fmt.Errorf("presign %s: %w", key, err)
	}
	return out.URL, nil
}

func isNoSuchBucket(err error) bool {
	var apiErr smithy.APIError
	if errors.As(err, &apiErr) {
		code := apiErr.ErrorCode()
		return strings.EqualFold(code, "NoSuchBucket") || strings.EqualFold(code, "NotFound")
	}
	return false
}