package erasure

import (
	"fmt"
	"strings"
)

type S3ShardConfig struct {
	ShardBucket          string `json:"aws_s3_shard_bucket"`
	ShardRegion          string `json:"aws_s3_shard_region"`
	CRRDestBucket        string `json:"aws_s3_crr_dest_bucket"`
	CRRDestRegion        string `json:"aws_s3_crr_dest_region"`
	CloudFrontDomain     string `json:"aws_cloudfront_domain,omitempty"`
	ReplicationRoleARN   string `json:"aws_s3_replication_role_arn,omitempty"`
	ReplicationAccountID string `json:"aws_account_id,omitempty"`
}

func S3ShardKey(token, region string, shardIndex int, shardHash string) string {
	token = strings.TrimSpace(token)
	region = strings.TrimSpace(region)
	shardHash = strings.TrimSpace(strings.ToLower(shardHash))
	if token == "" || region == "" || shardHash == "" {
		return ""
	}
	return fmt.Sprintf("shards/%s/%s/%d-%s.bin", token, region, shardIndex, shardHash)
}

func S3ShardMetadata(region string, shardIndex int, token, shardHash string) map[string]string {
	return map[string]string{
		"region":       strings.TrimSpace(region),
		"shard-index":  fmt.Sprintf("%d", shardIndex),
		"token":        strings.TrimSpace(token),
		"shard-hash":   strings.TrimSpace(strings.ToLower(shardHash)),
		"shard-advert": FormatShardAdvert(region, shardIndex),
	}
}

func FormatShardAdvert(region string, shardIndex int) string {
	return fmt.Sprintf("%s:%d", strings.TrimSpace(region), shardIndex)
}

func ParseShardAdvert(advert string) (region string, index int, ok bool) {
	advert = strings.TrimSpace(advert)
	colon := strings.LastIndex(advert, ":")
	if colon <= 0 {
		return "", 0, false
	}
	region = strings.TrimSpace(advert[:colon])
	if _, err := fmt.Sscanf(strings.TrimSpace(advert[colon+1:]), "%d", &index); err != nil {
		return "", 0, false
	}
	return region, index, region != ""
}

func BuildS3CRRRule(cfg S3ShardConfig) (map[string]interface{}, error) {
	if cfg.ShardBucket == "" || cfg.ShardRegion == "" || cfg.CRRDestBucket == "" || cfg.CRRDestRegion == "" {
		return nil, fmt.Errorf("aws s3 shard source/dest bucket and regions required")
	}
	role := strings.TrimSpace(cfg.ReplicationRoleARN)
	if role == "" {
		acct := strings.TrimSpace(cfg.ReplicationAccountID)
		if acct == "" {
			acct = "ACCOUNT_ID"
		}
		role = fmt.Sprintf("arn:aws:iam::%s:role/aetherforge-s3-shard-replication", acct)
	}
	dest := strings.TrimSpace(cfg.CRRDestBucket)
	if !strings.HasPrefix(dest, "arn:") {
		dest = "arn:aws:s3:::" + dest
	}
	return map[string]interface{}{
		"Role": role,
		"Rules": []map[string]interface{}{{
			"ID": "aetherforge-erasure-shard-crr", "Status": "Enabled", "Priority": 1,
			"Filter": map[string]interface{}{"Prefix": "shards/"},
			"Destination": map[string]interface{}{"Bucket": dest},
		}},
	}, nil
}