package hold

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"
	"time"
)

// CloudMetadata contains region info from cloud metadata service
type CloudMetadata struct {
	Region string
}

// metadataEndpoint is the cloud metadata service URL. Package-level var for test override.
var metadataEndpoint = "http://169.254.169.254"

// DetectCloudMetadata queries the instance metadata service (169.254.169.254)
// Currently supports UpCloud. Others can be added via PR.
func DetectCloudMetadata(ctx context.Context) (*CloudMetadata, error) {
	ctx, cancel := context.WithTimeout(ctx, 2*time.Second)
	defer cancel()

	// Try UpCloud metadata format
	if meta, err := detectUpCloud(ctx); err == nil {
		return meta, nil
	}

	// Add other providers here (AWS, GCP, Azure, DigitalOcean, etc.)
	// Contributors welcome!

	return nil, nil // No metadata available
}

// detectUpCloud queries UpCloud's metadata service
func detectUpCloud(ctx context.Context) (*CloudMetadata, error) {
	req, err := http.NewRequestWithContext(ctx, "GET", metadataEndpoint+"/metadata/v1.json", nil)
	if err != nil {
		return nil, err
	}

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()

	if resp.StatusCode != 200 {
		return nil, fmt.Errorf("metadata returned %d", resp.StatusCode)
	}

	var data struct {
		CloudName string `json:"cloud_name"`
		Region    string `json:"region"`
	}
	if err := json.NewDecoder(resp.Body).Decode(&data); err != nil {
		return nil, err
	}

	if data.CloudName != "upcloud" {
		return nil, fmt.Errorf("not upcloud: %s", data.CloudName)
	}

	return &CloudMetadata{
		Region: data.Region,
	}, nil
}