package orbit

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strings"
	"time"
)

// Options currently configures bootstrap health calls. Task, Worker and workflow
// clients will be added alongside their corresponding server endpoints.
type Options struct{ HTTPClient *http.Client }
type Client struct {
	baseURL string
	http    *http.Client
}
type Health struct {
	Status string `json:"status"`
	Scope  string `json:"scope,omitempty"`
}

// HTTPError exposes the status code without including sensitive response bodies.
type HTTPError struct{ StatusCode int }

func (e *HTTPError) Error() string { return fmt.Sprintf("orbit returned HTTP %d", e.StatusCode) }

func NewClient(baseURL string, opts Options) (*Client, error) {
	u, err := url.Parse(baseURL)
	if err != nil || u == nil || u.Host == "" || (u.Scheme != "http" && u.Scheme != "https") || u.User != nil || u.RawQuery != "" || u.Fragment != "" {
		return nil, errors.New("Orbit base URL must be absolute HTTP(S), without credentials, query or fragment")
	}
	client := opts.HTTPClient
	if client == nil {
		client = &http.Client{Timeout: 10 * time.Second}
	}
	clone := *client
	// Do not silently forward requests to another origin through redirects.
	clone.CheckRedirect = func(*http.Request, []*http.Request) error { return http.ErrUseLastResponse }
	return &Client{baseURL: strings.TrimRight(u.String(), "/"), http: &clone}, nil
}
func (c *Client) Liveness(ctx context.Context) (Health, error) { return c.health(ctx, "/health/live") }
func (c *Client) Readiness(ctx context.Context) (Health, error) {
	return c.health(ctx, "/health/ready")
}
func (c *Client) health(ctx context.Context, path string) (Health, error) {
	req, err := http.NewRequestWithContext(ctx, http.MethodGet, c.baseURL+path, nil)
	if err != nil {
		return Health{}, err
	}
	req.Header.Set("Accept", "application/json")
	response, err := c.http.Do(req)
	if err != nil {
		return Health{}, err
	}
	defer response.Body.Close()
	if response.StatusCode != http.StatusOK {
		return Health{}, &HTTPError{StatusCode: response.StatusCode}
	}
	const maxBody = 16 << 10
	body, err := io.ReadAll(io.LimitReader(response.Body, maxBody+1))
	if err != nil {
		return Health{}, err
	}
	if len(body) > maxBody {
		return Health{}, errors.New("Orbit health response exceeds limit")
	}
	var health Health
	if err := json.Unmarshal(body, &health); err != nil {
		return Health{}, fmt.Errorf("decode Orbit health response: %w", err)
	}
	if health.Status == "" {
		return Health{}, errors.New("Orbit health response is missing status")
	}
	return health, nil
}