//go:build dev

package s3

import (
	"context"
	"errors"
	"fmt"
	"io"
	"log"
	"os"
	"sync"

	"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/smithy-go"
)

var Client Uploader

// FallbackToInMemory reports whether the active S3 client is the in-memory
// fallback (placeholder cdn.example.com URLs, data lost on restart). It is
// declared here (dev build) and in s3.go (prod build, always false) so
// main.go can surface it from the health endpoint in both build variants.
var FallbackToInMemory bool

type Uploader interface {
	Upload(ctx context.Context, bucket, key string, body io.Reader, contentType string) error
	Download(ctx context.Context, bucket, key string, w io.Writer) error
	Delete(ctx context.Context, bucket, key string) error
	GetURL(ctx context.Context, bucket, key string) (string, error)
	HealthCheck(ctx context.Context) error
}

type S3Client struct {
	client    *s3.Client
	bucket    string
	publicURL string
}

// inMemS3 is an in-memory fallback for when RUSTFS is unavailable.
// Stored data is lost on process exit — suitable for test isolation.
type inMemS3 struct {
	mu      sync.Mutex
	objects map[string][]byte
}

func (m *inMemS3) Upload(_ context.Context, bucket, key string, body io.Reader, _ string) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	if m.objects == nil {
		m.objects = make(map[string][]byte)
	}
	data, err := io.ReadAll(body)
	if err != nil {
		return err
	}
	m.objects[bucket+"/"+key] = data
	return nil
}

func (m *inMemS3) Download(_ context.Context, bucket, key string, w io.Writer) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	data, ok := m.objects[bucket+"/"+key]
	if !ok {
		return fmt.Errorf("object %s/%s not found", bucket, key)
	}
	_, err := w.Write(data)
	return err
}

func (m *inMemS3) Delete(_ context.Context, bucket, key string) error {
	m.mu.Lock()
	defer m.mu.Unlock()
	delete(m.objects, bucket+"/"+key)
	return nil
}

func (m *inMemS3) GetURL(_ context.Context, bucket, key string) (string, error) {
	return fmt.Sprintf("https://cdn.example.com/%s/%s", bucket, key), nil
}

func (m *inMemS3) HealthCheck(_ context.Context) error {
	return nil
}

// isMissingBucket reports whether err is an S3 API error indicating the
// bucket itself does not exist (404 NoSuchBucket / NotFound) rather than a
// connectivity failure. The SDK v2 surfaces HeadBucket 404s as smithy.APIError
// implementations (*types.NotFound / *types.NoSuchBucket, or a generic API
// error); connection-level failures (refused, timeout, DNS, AccessDenied) do
// not implement smithy.APIError and return false.
func isMissingBucket(err error) bool {
	var apiErr smithy.APIError
	if !errors.As(err, &apiErr) {
		return false
	}
	switch apiErr.ErrorCode() {
	case "NoSuchBucket", "NotFound":
		return true
	default:
		return false
	}
}

func Connect() error {
	FallbackToInMemory = false
	// Check for RUSTFS_* vars first (matching compose.yml), fall back to S3_* vars
	endpoint := os.Getenv("RUSTFS_ENDPOINT")
	if endpoint == "" {
		endpoint = os.Getenv("S3_ENDPOINT")
	}
	if endpoint == "" {
		// Default: localhost for bare metal dev, use rustfs:9000 for docker
		endpoint = "http://localhost:9000"
	}

	accessKey := os.Getenv("RUSTFS_ACCESS_KEY")
	if accessKey == "" {
		accessKey = os.Getenv("S3_ACCESS_KEY")
	}
	if accessKey == "" {
		accessKey = "minioadmin"
	}

	secretKey := os.Getenv("RUSTFS_SECRET_KEY")
	if secretKey == "" {
		secretKey = os.Getenv("S3_SECRET_KEY")
	}
	if secretKey == "" {
		secretKey = "minioadmin"
	}

	bucket := os.Getenv("RUSTFS_BUCKET")
	if bucket == "" {
		bucket = os.Getenv("S3_BUCKET")
	}
	if bucket == "" {
		bucket = "crussell"
	}

	profilePicsBucket := os.Getenv("S3_PROFILE_PICS_BUCKET")
	if profilePicsBucket == "" {
		profilePicsBucket = "crussell-profile-pics"
	}

	region := os.Getenv("AWS_REGION")
	if region == "" {
		region = "eu-west-2"
	}

	publicURL := os.Getenv("S3_PUBLIC_URL")
	if publicURL == "" {
		publicURL = endpoint
	}

	awsCfg, err := awsconfig.LoadDefaultConfig(context.Background(),
		awsconfig.WithRegion(region),
		awsconfig.WithCredentialsProvider(credentials.NewStaticCredentialsProvider(
			accessKey,
			secretKey,
			"",
		)),
	)
	if err != nil {
		log.Printf("S3: AWS config failed (%v) — falling back to in-memory S3", err)
		log.Printf("S3 WARNING: portfolio/photo uploads will use in-memory storage with placeholder URLs (cdn.example.com) and data is LOST on restart")
		FallbackToInMemory = true
		Client = &inMemS3{}
		return nil
	}

	// Attempt RUSTFS/S3 connection; fall back to in-memory on genuine
	// server-unreachability only.
	ctx := context.Background()
	s3Raw := s3.NewFromConfig(awsCfg, func(o *s3.Options) {
		o.BaseEndpoint = aws.String(endpoint)
		o.UsePathStyle = true
	})

	// Create the primary bucket before probing: a fresh data volume has no
	// bucket yet, so a pre-probe HeadBucket 404 must not be mistaken for an
	// unreachable server. Creation errors are non-fatal.
	_, err = s3Raw.CreateBucket(ctx, &s3.CreateBucketInput{
		Bucket: aws.String(bucket),
	})
	if err != nil {
		log.Printf("Bucket creation: %v (may already exist)", err)
	}

	// Create the profile-pics bucket first too, so a fresh volume gets both
	// buckets before the connectivity probe runs.
	if profilePicsBucket != bucket {
		_, err = s3Raw.CreateBucket(ctx, &s3.CreateBucketInput{
			Bucket: aws.String(profilePicsBucket),
		})
		if err != nil {
			log.Printf("Profile pics bucket creation: %v (may already exist)", err)
		}
	}

	// Connectivity probe. A missing bucket (404 NoSuchBucket/NotFound) must
	// never trigger the in-memory fallback — it would persist placeholder
	// URLs; only connection-level failures fall back.
	_, err = s3Raw.HeadBucket(ctx, &s3.HeadBucketInput{Bucket: aws.String(bucket)})
	if err != nil {
		if isMissingBucket(err) {
			log.Printf("S3: bucket %q still missing after CreateBucket (%v) — keeping the real client; uploads may fail until the bucket exists", bucket, err)
		} else {
			log.Printf("S3: RUSTFS not reachable at %s (%v) — falling back to in-memory S3", endpoint, err)
			log.Printf("S3 WARNING: portfolio/photo uploads will use in-memory storage with placeholder URLs (cdn.example.com) and data is LOST on restart")
			FallbackToInMemory = true
			Client = &inMemS3{}
			return nil
		}
	}

	Client = &S3Client{
		client:    s3Raw,
		bucket:    bucket,
		publicURL: publicURL,
	}

	// Set bucket policy for public read access
	policy := fmt.Sprintf(`{
		"Version": "2012-10-17",
		"Statement": [{
			"Sid": "PublicReadGetObject",
			"Effect": "Allow",
			"Principal": "*",
			"Action": "s3:GetObject",
			"Resource": "arn:aws:s3:::%s/*"
		}]
	}`, bucket)
	_, err = s3Raw.PutBucketPolicy(ctx, &s3.PutBucketPolicyInput{
		Bucket: aws.String(bucket),
		Policy: aws.String(policy),
	})
	if err != nil {
		log.Printf("Bucket policy: %v (may already exist)", err)
	}

	// Profile pics bucket policy
	if profilePicsBucket != bucket {
		profilePolicy := fmt.Sprintf(`{
			"Version": "2012-10-17",
			"Statement": [{
				"Sid": "PublicReadGetObject",
				"Effect": "Allow",
				"Principal": "*",
				"Action": "s3:GetObject",
				"Resource": "arn:aws:s3:::%s/*"
			}]
		}`, profilePicsBucket)
		_, err = s3Raw.PutBucketPolicy(ctx, &s3.PutBucketPolicyInput{
			Bucket: aws.String(profilePicsBucket),
			Policy: aws.String(profilePolicy),
		})
		if err != nil {
			log.Printf("Profile pics bucket policy: %v (may already exist)", err)
		}
	}

	log.Printf("Connected to local S3 (Rustfs): bucket=%s, endpoint=%s", bucket, endpoint)
	return nil
}

func (s *S3Client) Upload(ctx context.Context, bucket, key string, body io.Reader, contentType string) error {
	_, err := s.client.PutObject(ctx, &s3.PutObjectInput{
		Bucket:      aws.String(bucket),
		Key:         aws.String(key),
		Body:        body,
		ContentType: aws.String(contentType),
	})
	return err
}

func (s *S3Client) Download(ctx context.Context, bucket, key string, w io.Writer) error {
	result, err := s.client.GetObject(ctx, &s3.GetObjectInput{
		Bucket: aws.String(bucket),
		Key:    aws.String(key),
	})
	if err != nil {
		return err
	}
	defer result.Body.Close()

	_, err = io.Copy(w, result.Body)
	return err
}

func (s *S3Client) Delete(ctx context.Context, bucket, key string) error {
	_, err := s.client.DeleteObject(ctx, &s3.DeleteObjectInput{
		Bucket: aws.String(bucket),
		Key:    aws.String(key),
	})
	return err
}

func (s *S3Client) GetURL(ctx context.Context, bucket, key string) (string, error) {
	return fmt.Sprintf("%s/%s/%s", s.publicURL, bucket, key), nil
}

func (s *S3Client) HealthCheck(ctx context.Context) error {
	_, err := s.client.HeadBucket(ctx, &s3.HeadBucketInput{
		Bucket: aws.String(s.bucket),
	})
	if err != nil {
		return fmt.Errorf("S3 bucket %q is not accessible (check S3_PUBLIC_URL / RUSTFS_ENDPOINT config): %w", s.bucket, err)
	}
	return nil
}