// Package frostfs provides HTTP-01 solver that saves challenge token to
// FrostFS to make it available to multiple hosts at once.
// Useful for deploying FrostFS gateways (HTTP or S3)
package frostfs

import (
	"context"
	"errors"
	"fmt"
	"strconv"
	"strings"
	"time"

	"github.com/go-acme/lego/v4/challenge"
)

const (
	// Challenge token will be garbage collected sometime after this interval
	// even if Cleanup() call fails for whatever reason.
	tokenLifetime = 1 * time.Hour
)

// HTTPProvider is a custom solver for HTTP-01 challenge that saves token to FrostFS.
type HTTPProvider struct {
	frostfs *Storage
	oid     string
}

var _ challenge.Provider = new(HTTPProvider)

func NewHTTPProvider(endpoint, cid, walletPath, walletAccount, walletPassword string) (*HTTPProvider, error) {
	if endpoint == "" {
		return nil, errors.New("empty endpoint")
	}
	if cid == "" {
		return nil, errors.New("empty container id")
	}
	key, err := getKey(walletPath, walletAccount, walletPassword)
	if err != nil {
		return nil, err
	}
	storage, err := Open(endpoint, cid, key)
	if err != nil {
		return nil, err
	}
	return &HTTPProvider{frostfs: storage}, nil
}

func (w *HTTPProvider) Present(domain, token, keyAuth string) error {
	if strings.Contains(token, "/") {
		return fmt.Errorf("token with slash character is not supported: %s", token)
	}
	if w.oid != "" {
		return fmt.Errorf("%T is not safe to re-enter: object was saved and not yet cleaned up: %s", w, w.oid)
	}

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	var err error
	expires, err := w.frostfs.Epoch(ctx, time.Now().Add(tokenLifetime))
	if err != nil {
		return fmt.Errorf("failed to calculate token expiration: %w", err)
	}
	w.oid, err = w.frostfs.Save(
		ctx,
		[]byte(keyAuth),
		"FileName", token,
		"ACME", token,
		"__SYSTEM__EXPIRATION_EPOCH", strconv.FormatUint(expires, 10),
	)
	return err
}

func (w *HTTPProvider) CleanUp(domain, token, keyAuth string) error {
	if w.oid == "" {
		panic("Cleanup() called before Present()")
	}
	err := w.frostfs.Delete(context.TODO(), w.oid)
	if err != nil {
		return err
	}
	w.oid = ""
	return nil
}