package collaboration

import (
	"crypto/rand"
	"crypto/sha256"
	"encoding/hex"
	"fmt"
	"time"

	"github.com/limeleaf/diffdown/internal/db"
	"github.com/limeleaf/diffdown/internal/model"
)

func GenerateInviteToken() (string, error) {
	bytes := make([]byte, 32)
	if _, err := rand.Read(bytes); err != nil {
		return "", err
	}
	hash := sha256.Sum256(bytes)
	return hex.EncodeToString(hash[:]), nil
}

func CreateInvite(database *db.DB, documentRKey, createdByDID string) (*model.Invite, error) {
	token, err := GenerateInviteToken()
	if err != nil {
		return nil, err
	}

	invite := &model.Invite{
		ID:           db.NewID(),
		DocumentRKey: documentRKey,
		Token:        token,
		CreatedBy:    createdByDID,
		CreatedAt:    time.Now(),
		ExpiresAt:    time.Now().Add(7 * 24 * time.Hour),
	}

	err = database.CreateInvite(invite)
	return invite, err
}

func ValidateInvite(database *db.DB, token, documentRKey string) (*model.Invite, error) {
	invite, err := database.GetInviteByToken(token)
	if err != nil {
		return nil, err
	}
	if invite.DocumentRKey != documentRKey {
		return nil, fmt.Errorf("invite does not match document")
	}
	if time.Now().After(invite.ExpiresAt) {
		return nil, fmt.Errorf("invite expired")
	}
	return invite, nil
}