using System.Net.Http.Headers;
using System.Net.Mail;
using System.Security.Cryptography;
using System.Text;
using System.Text.Json.Nodes;
using System.Text.RegularExpressions;
using InnovEnergy.App.Backend.Model;
using InnovEnergy.App.Backend.Utils;
using InnovEnergy.Lib.Utils;


namespace InnovEnergy.App.Backend.Database;

public static partial class Db
{
    public static IEnumerable<User> GetChildUsers(this User parent)
    {
        return Users
              .Where(f => f.ParentId == parent.Id);
    }

    public static IEnumerable<User> GetDescendantUsers(this User parent)
    {
        return parent.Traverse(GetChildUsers);
    }

    public static Boolean IsDescendantOf(this User user, User ancestor)
    {
        return Ancestors(user)
              .Any(u => u.Id == ancestor.Id);
    }
    
    private static IEnumerable<User> Ancestors(this User child)
    {
        return child.Unfold(GetParent);
    }

    public static User? GetParent(this User u)
    {
        return IsRoot(u)    
             ? null 
             : GetUserById(u.ParentId);
    }

    public static Boolean IsRoot(this User u)
    { 
        return u.ParentId == 0; // root has ParentId 0 by definition
    }

    public static Boolean HasDirectAccessToFolder(this User user, Folder folder)
    {
        return HasDirectAccessToFolder(user, folder.Id);
    }
    
    public static Boolean HasDirectAccessToFolder(this User user, Int64 folderId)
    {
        return User2Folder.Any(r => r.FolderId == folderId && r.UserId == user.Id);
    }
    
    public static Boolean HasAccessToFolder(this User user, Int64 folderId)
    {
        var folder = GetFolderById(folderId);
        if (folder is null)
            return false;

        return Ancestors(folder).Any(f => HasDirectAccessToFolder(user, f));
    }

    public static User? GetUserByEmail(String email) => Users.FirstOrDefault(u => u.Email == email);

    public static Int64 CreateUser(User user)
    {
        if (GetUserByEmail(user.Email) is not null)
            return -1; // TODO: User with that email already exists

        //Salting and Hashing password
        var salt = Crypto.GenerateSalt();
        var hashedPassword = Crypto.ComputeHash(Encoding.UTF8.GetBytes(user.Password),
            Encoding.UTF8.GetBytes(salt + "innovEnergy"));

        user.Salt = salt;
        user.Password = hashedPassword;

        return Create(user);
    }


    private static Byte[] HmacSha256Digest(String message, String secret)
    {
        var encoding      = new UTF8Encoding(); 
        var keyBytes      = encoding.GetBytes(secret);
        var messageBytes  = encoding.GetBytes(message);
        var cryptographer = new HMACSHA256(keyBytes);

        return cryptographer.ComputeHash(messageBytes);
    }
    
    private static String BuildSignature(String method, String path, String data, Int64 time, String secret)
    {
        var messageToSign = "";
        messageToSign += method + " /v2/" + path + "\n";
        messageToSign += data + "\n";

        // query strings
        messageToSign += "\n";
        // headers
        messageToSign += "\n";

        messageToSign += time;

        Console.WriteLine("Message to sign:\n" + messageToSign);

        var hmac = HmacSha256Digest(messageToSign, secret);
        return Convert.ToBase64String(hmac);
    }
    
    // public Object CreateAndSaveUserS3ApiKey(User user)
    // {
    //     //EXOSCALE API URL
    //     const String url = "https://api-ch-dk-2.exoscale.com/v2/";
    //     const String path = "access-key";
    //     
    //     //TODO HIDE ME
    //     const String secret = "S2K1okphiCSNK4mzqr4swguFzngWAMb1OoSlZsJa9F0";
    //     const String apiKey = "EXOb98ec9008e3ec16e19d7b593";
    //
    //     var installationList = User2Installation
    //         .Where(i => i.UserId == user.Id)
    //         .SelectMany(i => Installations.Where(f => i.InstallationId == f.Id))
    //         .ToList();
    //
    //    
    //     var instList = new JsonArray();
    //     
    //     foreach (var installation in installationList)
    //     {
    //         instList.Add(new JsonObject {["domain"] = "sos",["resource-name"] = installation.Name,["resource-type"] = "bucket"});
    //     }
    //     
    //     var jsonPayload = new JsonObject { ["name"] = user.Email, ["operations"] = new JsonArray{ "list-sos-bucket", "get-sos-object" }, ["content"] = instList};
    //     var stringPayload = jsonPayload.ToJsonString();
    //     
    //     var unixExpiration = DateTimeOffset.UtcNow.ToUnixTimeSeconds()+60;
    //     var signature = BuildSignature("POST", path, stringPayload, unixExpiration , secret);
    //
    //     var authHeader = "credential="+apiKey+",expires="+unixExpiration+",signature="+signature;
    //     
    //     var client = new HttpClient();
    //     client.DefaultRequestHeaders.Authorization =
    //         new AuthenticationHeaderValue("EXO2-HMAC-SHA256", authHeader);
    //
    //     var content = new StringContent(stringPayload, Encoding.UTF8, "application/json");
    //
    //
    //     var response = client.PostAsync(url+path, content).Result;
    //     
    //     if (response.StatusCode.ToString() != "OK")
    //     {
    //         return response;
    //     }
    //
    //     var responseString = response.Content.ReadAsStringAsync().Result;
    //     return Enumerable.Last(Regex.Match(responseString, "key\\\":\\\"([A-Z])\\w+").ToString().Split('"'));
    //     // return SetUserS3ApiKey(user, newKey);
    //     
    // }
    
    public static Object CreateAndSaveInstallationS3ApiKey(Installation installation)
    {
        //EXOSCALE API URL
        const String url = "https://api-ch-dk-2.exoscale.com/v2/";
        const String path = "access-key";
        
        //TODO HIDE ME
        const String secret = "S2K1okphiCSNK4mzqr4swguFzngWAMb1OoSlZsJa9F0";
        const String apiKey = "EXOb98ec9008e3ec16e19d7b593";

        var instList = new JsonArray();
        instList.Add(new JsonObject {["domain"] = "sos",["resource-name"] = installation.Name,["resource-type"] = "bucket"});

        var jsonPayload = new JsonObject { ["name"] = installation.Id, ["operations"] = new JsonArray{ "list-sos-bucket", "get-sos-object" }, ["content"] = instList};
        var stringPayload = jsonPayload.ToJsonString();
        
        var unixExpiration = DateTimeOffset.UtcNow.ToUnixTimeSeconds()+60;
        var signature = BuildSignature("POST", path, stringPayload, unixExpiration , secret);

        var authHeader = "credential="+apiKey+",expires="+unixExpiration+",signature="+signature;
        
        var client = new HttpClient();
        client.DefaultRequestHeaders.Authorization =
            new AuthenticationHeaderValue("EXO2-HMAC-SHA256", authHeader);

        var content = new StringContent(stringPayload, Encoding.UTF8, "application/json");


        var response = client.PostAsync(url+path, content).Result;
        
        if (response.StatusCode.ToString() != "OK")
        {
            return response;
        }

        var responseString = response.Content.ReadAsStringAsync().Result;
        var newKey = Enumerable.Last(Regex.Match(responseString, "key\\\":\\\"([A-Z])\\w+").ToString().Split('"'));

        installation.S3Key = newKey;
        UpdateInstallation(installation);
        return newKey;
    }
    
    public static Boolean UpdateUser(User user)
    {
        var oldUser = GetUserById(user.Id);
        if (oldUser == null)
            return false; // TODO: "User doesn't exist"

        //Checking for unchangeable things
        // TODO: depends on privileges of caller 

        user.Id       = oldUser.Id;
        user.ParentId = oldUser.ParentId;
        user.Email    = oldUser.Email;

        return Update(user);
    }

    public static Boolean DeleteUser(User user)
    {
        User2Folder.Delete(u => u.UserId == user.Id);
        User2Installation.Delete(u => u.UserId == user.Id);

        //Todo check for orphaned Installations/Folders

        // GetChildUsers()

        return Delete(user);
    }


    // TODO
    private static Boolean IsValidEmail(String email)
    {
        try
        {
            var emailAddress = new MailAddress(email);
        }
        catch
        {
            return false;
        }

        return true;
    }
}