using System.Net;
using System.Text;
using InnovEnergy.App.Backend.Database;
using InnovEnergy.App.Backend.Model;
using InnovEnergy.App.Backend.Model.Relations;
using InnovEnergy.App.Backend.Utils;
using InnovEnergy.Lib.Utils;
using Microsoft.AspNetCore.Mvc;
using HttpContextAccessor = Microsoft.AspNetCore.Http.HttpContextAccessor;

namespace InnovEnergy.App.Backend.Controllers;

[ApiController]
[Route("api/")]
public class Controller  
{
    [Returns<String>]
    [Returns(HttpStatusCode.Unauthorized)]
    [Returns(HttpStatusCode.BadRequest)]
    [HttpPost($"{nameof(Login)}")]
    public Object Login(Credentials credentials)
    {
        if (String.IsNullOrWhiteSpace(credentials.Username) ||
            String.IsNullOrWhiteSpace(credentials.Password))
            return new HttpResponseMessage(HttpStatusCode.BadRequest);
        
        using var db = Db.Connect();
        var user = db.GetUserByEmail(credentials.Username);
        
        if (user is null)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);

        #if !DEBUG
        if (!VerifyPassword(credentials.Password, user))
             return new HttpResponseMessage(HttpStatusCode.Unauthorized);   
        #endif
        
        var ses = new Session(user);
        db.NewSession(ses);
        return ses.Token;
    }


    [Returns(HttpStatusCode.OK)]
    [Returns(HttpStatusCode.Unauthorized)]
    [HttpPost($"{nameof(Logout)}")]
    public Object Logout()
    {
        var caller = GetCaller();

        if (caller is null)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        using var db = Db.Connect();
        return db.DeleteSession(caller.Id);
    }
    
    
    [Returns(HttpStatusCode.OK)]
    [Returns(HttpStatusCode.Unauthorized)]
    [HttpPost($"{nameof(UpdateS3Credentials)}")]
    public Object UpdateS3Credentials()
    {
        // TODO: S3Credentials should be per session, not per user
        
        var caller = GetCaller();
        if (caller is null)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        using var db = Db.Connect();
        
        return db.CreateAndSaveUserS3ApiKey(caller);
    }
    

    [Returns<User>]
    [Returns(HttpStatusCode.Unauthorized)]
    [HttpGet($"{nameof(GetUserById)}")]
    public Object GetUserById(Int64 id)
    {
        var caller = GetCaller();
        if (caller is null)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        using var db = Db.Connect();

        var user = db
                  .GetDescendantUsers(caller)
                  .FirstOrDefault(u => u.Id == id);
        
        return user as Object ?? new HttpResponseMessage(HttpStatusCode.Unauthorized);
    }

    
    [Returns<Installation>]
    [Returns(HttpStatusCode.Unauthorized)]
    [HttpGet($"{nameof(GetInstallationById)}")]
    public Object GetInstallationById(Int64 id)
    {
        var caller = GetCaller();
        if (caller == null)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        using var db = Db.Connect();
        
        var installation = db
                          .GetAllAccessibleInstallations(caller)
                          .FirstOrDefault(i => i.Id == id);

        return installation as Object ?? new HttpResponseMessage(HttpStatusCode.NotFound);
    }

    
    [Returns<Folder>]
    [Returns(HttpStatusCode.Unauthorized)]
    [HttpGet($"{nameof(GetFolderById)}")]
    public Object GetFolderById(Int64 id)
    {
        var caller = GetCaller();
        if (caller == null)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        using var db = Db.Connect();
        
        var folder = db
                    .GetAllAccessibleFolders(caller)
                    .FirstOrDefault(f => f.Id == id);

        return folder as Object ?? new HttpResponseMessage(HttpStatusCode.NotFound);
    }
    
    
    [Returns<Installation[]>]  // assuming swagger knows about arrays but not lists (JSON) 
    [Returns(HttpStatusCode.Unauthorized)]
    [HttpGet($"{nameof(GetAllInstallations)}/")]
    public Object GetAllInstallations()
    {
        var caller = GetCaller();
        if (caller == null)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
   
        using var db = Db.Connect();
        
        return db
              .GetAllAccessibleInstallations(caller)
              .ToList(); // important!
    }
    
    
    [Returns<Folder[]>]  // assuming swagger knows about arrays but not lists (JSON)
    [Returns(HttpStatusCode.Unauthorized)]
    [HttpGet($"{nameof(GetAllFolders)}/")]
    public Object GetAllFolders()
    {
        var caller = GetCaller();
        if (caller == null)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);

        using var db = Db.Connect();
        return db
              .GetAllAccessibleFolders(caller)
              .ToList();  // important!
    }
    
    [Returns<TreeNode[]>]  // assuming swagger knows about arrays but not lists (JSON)
    [Returns(HttpStatusCode.Unauthorized)]
    [HttpGet($"{nameof(GetTree)}/")]
    public Object GetTree()
    {
        var caller = GetCaller();
        if (caller == null)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        using var db = Db.Connect();

        var folders = db
                     .GetDirectlyAccessibleFolders(caller) 
                     .Do(f => f.ParentId = 0) // ReSharper disable once AccessToDisposedClosure
                     .Select(f => PopulateChildren(db, f));
        
        var installations = db.GetDirectlyAccessibleInstallations(caller);

        return folders
              .Concat<TreeNode>(installations)
              .ToList(); // important!
    }

    private static Folder PopulateChildren(Db db, Folder folder, HashSet<Int64>? hs = null)
    {
        // TODO: remove cycle detector
        hs ??= new HashSet<Int64>();
        if (!hs.Add(folder.Id)) 
            throw new Exception("Cycle detected: folder " + folder.Id);

        var installations = db.GetChildInstallations(folder);
        var folders = db
                     .GetChildFolders(folder)
                     .Select(c => PopulateChildren(db, c, hs));
        
        folder.Children = folders.Concat<TreeNode>(installations).ToList();
     
        return folder;
    }


    [Returns(HttpStatusCode.OK)]
    [Returns(HttpStatusCode.Unauthorized)]
    [HttpPut($"{nameof(UpdateUser)}/")]
    public Object UpdateUser(User updatedUser)
    {
        // TODO: distinguish between create and update
        
        var caller = GetCaller();
        if (caller == null)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        using var db = Db.Connect();
        
        return db.GetUserById(updatedUser.Id) != null 
             ? db.UpdateUser(updatedUser) 
             : db.CreateUser(updatedUser);
    }
    
    
    [Returns(HttpStatusCode.OK)]
    [Returns(HttpStatusCode.Unauthorized)]
    [HttpPut($"{nameof(UpdateInstallation)}/")]
    public Object UpdateInstallation(Installation installation)
    {
        var caller = GetCaller();
        
        if (caller is null || !caller.HasWriteAccess)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        using var db = Db.Connect();
        
        var hasAccessToInstallation = db
                                     .GetAllAccessibleInstallations(caller)
                                     .Any(i => i.Id == installation.Id);
        
        if (!hasAccessToInstallation)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);

        // TODO: accessibility by other users etc
        // TODO: sanity check changes
        
        return db.UpdateInstallation(installation);
    }
    
    
    [Returns(HttpStatusCode.OK)]
    [Returns(HttpStatusCode.Unauthorized)]
    [HttpPut($"{nameof(UpdateFolder)}/")]
    public Object UpdateFolder(Folder folder)
    {
        var caller = GetCaller();
        
        if (caller is null || !caller.HasWriteAccess)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        using var db = Db.Connect();
        
        var hasAccessToFolder = db
                               .GetAllAccessibleFolders(caller)
                               .Any(f => f.Id == folder.Id);

        if (!hasAccessToFolder)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        // TODO: accessibility by other users etc
        // TODO: sanity check changes
                
        return db.UpdateFolder(folder);
    }
    
    [Returns(HttpStatusCode.OK)]
    [Returns(HttpStatusCode.Unauthorized)]
    [HttpDelete($"{nameof(DeleteUser)}/")]
    public Object DeleteUser(Int64 userId)
    {
        var caller = GetCaller();
        
        if (caller is null || !caller.HasWriteAccess)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        using var db = Db.Connect();
        
        var userToBeDeleted = db
                             .GetDescendantUsers(caller)
                             .FirstOrDefault(u => u.Id == userId);

        if (userToBeDeleted is null)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        return db.DeleteUser(userToBeDeleted);
    }
    
    [Returns(HttpStatusCode.OK)]
    [Returns(HttpStatusCode.Unauthorized)]
    [HttpDelete($"{nameof(DeleteInstallation)}/")]
    public Object DeleteInstallation(Int64 installationId)
    {
        var caller = GetCaller();
        
        if (caller is null || !caller.HasWriteAccess)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        using var db = Db.Connect();

        var installationToBeDeleted = db
                                     .GetAllAccessibleInstallations(caller)
                                     .FirstOrDefault(i => i.Id == installationId);
        
        if (installationToBeDeleted is null)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        return db.DeleteInstallation(installationToBeDeleted);
    }
    
    
    [ProducesResponseType(200)]
    [ProducesResponseType(401)]
    [HttpDelete($"{nameof(DeleteFolder)}/")]
    public Object DeleteFolder(Int64 folderId)
    {
        var caller = GetCaller();
        if (caller == null)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        using var db = Db.Connect();

        var folderToDelete = db
                            .GetAllAccessibleFolders(caller)
                            .FirstOrDefault(f => f.Id == folderId);
        
        if (folderToDelete is null)
            return new HttpResponseMessage(HttpStatusCode.Unauthorized);
        
        return db.DeleteFolder(folderToDelete);
    }
    

    private static User? GetCaller()
    {
        var ctxAccessor = new HttpContextAccessor();
        return ctxAccessor.HttpContext?.Items["User"] as User;
    }
    
    private static Boolean VerifyPassword(String password, User user)
    {
        var pwdBytes  = Encoding.UTF8.GetBytes(password);
        var saltBytes = Encoding.UTF8.GetBytes(user.Salt + "innovEnergy");
        var pwdHash   = Crypto.ComputeHash(pwdBytes, saltBytes);

        return user.Password == pwdHash;
    }

}