package registry

import (
	"encoding/json"
	"fmt"
	"io"
	"net/http"
)

type RegistryClient struct {
	URL      string
	Username string
	Password string
}

type CatalogResponse struct {
	Repositories []string `json:"repositories"`
}

func (c *RegistryClient) ListRepositories() ([]string, error) {
	repos := []string{}
	last := ""
	pageSize := 100

	for {
		url := fmt.Sprintf("%s/v2/_catalog?n=%d", c.URL, pageSize)
		if last != "" {
			url += "&last=" + last
		}

		req, _ := http.NewRequest("GET", url, nil)
		if c.Username != "" {
			req.SetBasicAuth(c.Username, c.Password)
		}

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

		if resp.StatusCode != http.StatusOK {
			body, _ := io.ReadAll(resp.Body)
			return nil, fmt.Errorf("registry returned %d: %s", resp.StatusCode, body)
		}

		var catalog CatalogResponse
		if err := json.NewDecoder(resp.Body).Decode(&catalog); err != nil {
			return nil, err
		}

		repos = append(repos, catalog.Repositories...)

		if len(catalog.Repositories) < pageSize {
			break
		}

		last = catalog.Repositories[len(catalog.Repositories)-1]
	}

	return repos, nil
}