const z = @import( "std" );
const zap = @import( "zap" );
const api = @import( "api.zig" );
const req = @import( "req.zig" );
const net = @import( "net-util.zig" );
const model = @import( "model.zig" );

const u = struct {
  usingnamespace @import( "util.zig" );
  usingnamespace @import( "userdefs.zig" );
  usingnamespace @import( "user.zig" );
  usingnamespace @import( "userdata.zig" );
};

// --------------------------------------------------------------------------------------------------------
// some docs because this is becoming a little complex:
// the api is mostly a proxy between the user and model instances
// user sends ChatReq to api, api forwards a ModelInstanceChatReq to instance after verifying user acc etc
// instance replies with a ChatStream defined in typescript [api-defs.ts](file://../instance/api-defs.ts#L58)
// api simply forwards this ChatStream to the client, only parsing it to check for a title.
// if a title is present, it's updated in the user db entry.
//
// the situation looks similar for the generate endpoint except there are no title checks.
// the msg is simply proxied to the user.
//
// legend:
// (source) - message source
// [type] - message type
// {target} - message target
// @/ - route
//
// chat route:
// (user) [ChatReq] req @/chat --> (api) [ModelInstanceChatReq] req @/chat --> {instance}
// (instance) [ChatStream] res --> (api) proxy --> {user}
//
// generate route:
// (user) [GenerateReq] req @/generate --> (api) [ModelInstanceGenerateReq] req @/generate --> {instance}
// (instance) [undefined in zig] res --> (api) proxy --> {user}
// --------------------------------------------------------------------------------------------------------

const ArrayList = z.ArrayList;
const ErrRes = net.ErrorResponse;
const OkRes = net.OkResponse;
const Request = zap.Request;

const memeql = z.mem.eql;

const alloc = u.alloc;

pub const title_gen_model = "qwen2.5-1.5b";
pub const routes = .{
  .@"chat" = chat,
  .@"get-chat" = getChat,
  .@"generate" = generate,
  .@"create-chat" = createChat,
  .@"delete-chat" = deleteChat,
  .@"get-chat-name" = getChatName
};

const ToolCall = struct {
  name: []const u8,
  parameters: struct {
    pub const @"getty.db" = u.@"json.ignore.unknown";
  }// processed either by instance or client, we dont care abt the contents
};

const MsgFile = struct {
  name: []const u8,
  type: []const u8,
  content: []const u8
};

const Msg = struct {
  content: []const u8,
  role: []const u8,
  timestamp: []const u8,
  toolCall: ?ToolCall = null,
  images: ?[][]const u8 = null,
  files: ?[]MsgFile = null,

  pub const @"getty.db" = u.@"json.ignore.unknown";
};

const ClientOptions = struct {
  seed: ?u32,
  temperature: ?f32,

  pub const @"getty.db" = u.@"json.ignore.unknown";
};

const ChatReq = struct {
  model: []const u8,
  messages: []Msg,
  system: ?[]const u8,
  chatfile: ?[]const u8 = null,
  options: ?ClientOptions = null,
  generateTitle: ?bool = null,

  pub const @"getty.db" = u.@"json.ignore.unknown";
};

const ChatStream = struct {
  status: []const u8,
  done: bool,
  title: ?[]const u8,

  pub const @"getty.db" = u.@"json.ignore.unknown";
};

const GenerateReq = struct {
  model: []const u8,
  prompt: []const u8,
  suffix: ?[]const u8 = "",
  options: ?ClientOptions = null,

  pub const @"getty.db" = u.@"json.ignore.unknown";
};

const GetChatReq = struct {
  chatId: []const u8,

  pub const @"getty.db" = u.@"json.ignore.unknown";
};

const ChatMsgContext = struct {
  uuid: []const u8,
  chatfile: []const u8
};


// theres no reason for these to be split up other than the frontend being suck
// todo later: fix
const ModelInstanceChatOptions = struct {
  system: ?struct {
    model: ?[]const u8 = null,
    user: ?[]const u8 = null,
  },
  model: model.Model,
  uuid: []const u8,
  chatfile: ?[]const u8 = null,
  generateTitle: ?bool = null,
};

const ModelInstanceChatReq = struct {
  messages: []Msg,
  options: ModelInstanceChatOptions,
};

const ModelInstanceGenerateOptions = struct {
  model: model.Model,
  system: ?struct {
    model: ?[]const u8 = null,
    user: ?[]const u8 = null,
  } = null,
};

const ModelInstanceGenerateReq = struct {
  options: ModelInstanceGenerateOptions,
  prompt: []const u8,
  suffix: ?[]const u8,
};

///forwards the instance error to client if reported
///sends a 500 otherwise
fn handleInstanceError( r: Request, q: *const req.Result ) void {
  if( q.body ) |body| {
    const msg = u.jsonParse( struct { status: []const u8, msg: []const u8 }, body ) catch null;
    if( msg != null ) {
      z.debug.print( "res err status [{any}]: {s}\n", .{ q.status, body } );
      r.sendChunk( body ) catch {};
    }
  } else {
    net.sendJsonChunk( r, .internal_server_error, ErrRes{ .msg = "could not contact server" } );
  }
}


// -------------------------------------------------------------------------------------------
// chat --------------------------------------------------------------------------------------

fn chatChunkFn( chunk: []const u8, r: Request ) void {
  const ctx = r.getUserContext( ChatMsgContext );
  var parts = z.mem.split( u8, chunk, "\n" );
  var part: ?[]const u8 = parts.first();
  while( part ) |p| : (part = parts.next()) {
    if( p.len == 0 )
      continue;

    var buf = alloc.alloc( u8, p.len + 1 ) catch return;
    defer alloc.free( buf );
    @memcpy( buf[0..p.len], p );
    buf[p.len] = '\n';

    if( ctx ) |_ctx| {
      if( u.jsonParse( ChatStream, buf ) catch null ) |parsed| {
        if( parsed.v.done and parsed.v.title != null ) {
          setChatTitle( _ctx.uuid, _ctx.chatfile, parsed.v.title.? );
        }

        parsed.deinit();
      }
    }

    r.sendChunk( buf ) catch |e| {
      z.debug.print( "error sending chunk: {any}\n", .{e} );
    };
  }
}

fn startChat( r: Request, address: []const u8, params: ChatReq, uuid: []const u8, user: *u.UserEntry ) void {
  const _model = model.getModelByDisplayName( params.model ) catch {
    return net.sendJsonChunk( r, .bad_request, ErrRes{ .msg = "invalid model" } );
  };

  if( !model.canBeUsedByUser( _model.*, user ) ) {
    return net.sendJson( r, .unauthorized, ErrRes{ .msg = "user is not authorized to use this model" } );
  }

  const chat_req = ModelInstanceChatReq{
    .messages = params.messages,
    .options = ModelInstanceChatOptions{
      .model = _model.*,
      .system = .{
        .model = _model.system,
        .user = params.system,
      },
      .uuid = uuid,
      .chatfile = params.chatfile,
      .generateTitle = params.generateTitle
    },
  };

  if( params.chatfile ) |chatfile| {
    var ctx = ChatMsgContext{
      .uuid = uuid,
      .chatfile = chatfile
    };
    r.setUserContext( &ctx );
  }

  const params_str = u.jsonStringify( chat_req ) catch {
    return net.sendJson( r, .bad_request, ErrRes{ .msg = "invalid request format" } );
  }; defer alloc.free( params_str );

  r.setChunked() catch {
    return net.sendJson( r, .internal_server_error, ErrRes{ .msg = "internal server error" } );
  };
  const q = req.sendWithData( Request, .{
    .method = .POST,
    .url = address,
    .headers = &[_]z.http.Header{ .{ .name = "Content-Type", .value = "application/json" } },
    .body = params_str,
    .chunk_fn = chatChunkFn,
    .chunk_data = r
  }, alloc );
  defer q.deinit();

  if( !q.ok )
    handleInstanceError( r, &q );
  r.endStream() catch |e| {
    return z.debug.print( "error closing connection {any} {any}", .{e, @errorReturnTrace() } );
  };
}

///route @/chat
fn chat( r: Request ) void {
  if( net.handleInvalidPostReq( r ) ) return;
  u.checkDbOnThread() catch return;

  const uuid = u.uuidFromApiOrAuthToken( r ) catch return;
  defer alloc.free( uuid );

  const params = u.jsonParse( ChatReq, r.body.? ) catch |e| {
    z.debug.print( "err: {any}\n", .{e} );
    return net.sendJson( r, .bad_request, ErrRes{ .msg = "invalid request format" } );
  }; defer params.deinit();

  var user = u.getEntry( uuid ) catch {
    return net.sendJson( r, .unauthorized, ErrRes{ .msg = "user not found" } );
  }; defer user.db_entry.?.deinit();

  u.checkSubscription( &user ) catch {
    return net.sendJson( r, .internal_server_error, ErrRes{ .msg = "internal server error" } );
  };

  var prefs = u.getSettings( uuid ) catch {
    return net.sendJson( r, .unauthorized, ErrRes{ .msg = "error getting user data" } );
  }; defer prefs.db_entry.?.deinit();

  if( params.v.chatfile != null and !u.hasChat( &prefs, params.v.chatfile.? ) )
    return net.sendJson( r, .bad_request, ErrRes{ .msg = "specified chat file does not exist" } );

  const serv = api.getAvailableServer( params.v.model, alloc ) orelse {
    return net.sendJson( r, .service_unavailable, ErrRes{ .msg = "no server available" } );
  }; defer alloc.free( serv );

  api.markServerAsBusy( serv ) catch {
    return net.sendJson( r, .internal_server_error, ErrRes{ .msg = "internal server error" } );
  };

  const address = z.fmt.allocPrintZ( alloc, "{s}/chat", .{serv} ) catch return;
  defer alloc.free( address );
  startChat( r, address, params.v, uuid, &user );
}

fn setChatTitle( uuid: []const u8, chatfile: []const u8, title: []const u8 ) void {
  var prefs = u.getSettings( uuid ) catch {
    return z.debug.print( "setChatTitle called for invalid uuid: {s}\n", .{uuid} );
  }; defer prefs.db_entry.?.deinit();

  if( prefs.chat_files == null and prefs.chat_files.?.files == null )
    return;

  const files = prefs.chat_files.?.files.?;
  for( files ) |*f| {
    if( memeql( u8, f.id, chatfile ) ) {
      f.name = title;
      break;
    }
  }
  prefs.chat_files = u.ChatFiles{ .files = files };
  u.updateSettings( &prefs ) catch {};
}

// -------------------------------------------------------------------------------------------
// generate ----------------------------------------------------------------------------------

fn generateChunkFn( chunk: []const u8, r: Request ) void {
  var parts = z.mem.split( u8, chunk, "\n" );
  var part: ?[]const u8 = parts.first();
  while( part ) |p| : (part = parts.next()) {
    if( p.len == 0 )
      continue;

    var buf = alloc.alloc( u8, p.len + 1 ) catch return;
    defer alloc.free( buf );
    @memcpy( buf[0..p.len], p );
    buf[p.len] = '\n';

    r.sendChunk( buf ) catch |e| {
      z.debug.print( "error sending chunk: {any}\n", .{e} );
    };
  }
}

fn startGenerate( r: Request, address: []const u8, params: GenerateReq, user: *u.UserEntry ) void {
  const _model = model.getModelByDisplayName( params.model ) catch {
    const json = u.jsonStringify( ErrRes{ .msg = "invalid model" } ) catch "";
    defer alloc.free( json );
    return r.sendChunk( json ) catch {};
  };

  if( !model.canBeUsedByUser( _model.*, user ) ) {
    return net.sendJson( r, .unauthorized, ErrRes{ .msg = "user is not authorized to use this model" } );
  }

  const gen_req = ModelInstanceGenerateReq{
    .options = ModelInstanceGenerateOptions{
      .model = _model.*,
    },
    .prompt = params.prompt,
    .suffix = params.suffix,
  };

  const params_str = u.jsonStringify( gen_req ) catch {
    return net.sendJsonChunk( r, .bad_request, ErrRes{ .msg = "invalid request format" } );
  }; defer alloc.free( params_str );

  r.setChunked() catch {
    return net.sendJson( r, .internal_server_error, ErrRes{ .msg = "internal server error" } );
  };
  const q = req.sendWithData( Request, .{
    .method = .POST,
    .url = address,
    .headers = &[_]z.http.Header{ .{ .name = "Content-Type", .value = "application/json" } },
    .body = params_str,
    .chunk_fn = generateChunkFn,
    .chunk_data = r
  }, alloc );
  defer q.deinit();

  if( !q.ok )
    handleInstanceError( r, &q );
  r.endStream() catch |e| {
    return z.debug.print( "error closing connection {any} {any}", .{e, @errorReturnTrace() } );
  };
}

///route @/generate
fn generate( r: Request ) void {
  if( net.handleInvalidPostReq( r ) ) return;
  u.checkDbOnThread() catch return;

  const uuid = u.uuidFromApiOrAuthToken( r ) catch return;
  defer alloc.free( uuid );

  const params = u.jsonParse( GenerateReq, r.body.? ) catch |e| {
    z.debug.print( "error parsing request {any}", .{e} );
    return net.sendJson( r, .bad_request, ErrRes{ .msg = "invalid request format" } );
  }; defer params.deinit();

  var user = u.getEntry( uuid ) catch {
    return net.sendJson( r, .not_found, ErrRes{ .msg = "user not found" } );
  }; defer user.db_entry.?.deinit();

  u.checkSubscription( &user ) catch {
    return net.sendJson( r, .internal_server_error, ErrRes{ .msg = "internal server error" } );
  };

  const serv = api.getAvailableServer( params.v.model, alloc ) orelse {
    return net.sendJson( r, .service_unavailable, ErrRes{ .msg = "no server available" } );
  }; defer alloc.free( serv );

  api.markServerAsBusy( serv ) catch {
    return net.sendJson( r, .internal_server_error, ErrRes{ .msg = "internal server error" } );
  };

  const address = z.fmt.allocPrintZ( alloc, "{s}/generate", .{serv} ) catch return;
  defer alloc.free( address );
  startGenerate( r, address, params.v, &user );
}



// -------------------------------------------------------------------------------------------
// chat management (create-chat, delete-chat, get-chat, get-chat-name) -----------------------

///route @/create-chat
fn createChat( r: Request ) void {
  if( net.handleInvalidPostReq( r ) ) return;
  u.checkDbOnThread() catch return;

  const uuid = u.uuidFromApiOrAuthToken( r ) catch return;
  defer alloc.free( uuid );

  var userdata = u.getSettings( uuid ) catch {
    return net.sendJson( r, .not_found, ErrRes{ .msg = "user not found" } );
  }; defer userdata.db_entry.?.deinit();

  var chats = userdata.chat_files;
  if( chats == null )
    chats = u.ChatFiles{ .files = &[_]u.ChatEntry{} };

  const files = chats.?.files;
  var list = ArrayList( u.ChatEntry ).init( alloc );
  defer list.deinit();

  if( files != null and files.?.len > 0 )
    list.appendSlice( files.? ) catch {};

  const chat_uuid = net.uuidv4();
  var buf = [_]u8{ 0 } ** 64;
  const dup = z.fmt.bufPrintZ( &buf, "{s}", .{chat_uuid} ) catch &chat_uuid;
  const new_entry = u.ChatEntry{
    .id = dup,
    .name = "new chat"
  };

  list.append( new_entry ) catch {};
  chats.?.files = list.items;
  userdata.chat_files = chats;
  u.updateSettings( &userdata ) catch {
    return net.sendJson( r, .internal_server_error, ErrRes{ .msg = "internal server error" } );
  };

  return net.sendJson( r, .ok, OkRes( .{ .chatId = dup } ) );
}

///route @/get-chat
fn getChat( r: Request ) void {
  if( net.handleInvalidPostReq( r ) ) return;
  u.checkDbOnThread() catch return;

  const uuid = u.uuidFromApiOrAuthToken( r ) catch return;
  defer alloc.free( uuid );

  const params = u.jsonParse( GetChatReq, r.body.? ) catch {
    return net.sendJson( r, .bad_request, ErrRes{ .msg = "invalid request format" } );
  }; defer params.deinit();

  const userdata = u.getSettings( uuid ) catch {
    return net.sendJson( r, .internal_server_error, ErrRes{ .msg = "user not found" } );
  }; defer userdata.db_entry.?.deinit();

  const chats = userdata.chat_files;
  if( chats == null or chats.?.files == null )
    return net.sendJson( r, .not_found, ErrRes{ .msg = "chat not found" } );

  for( chats.?.files.? ) |file| {
    const id = file.id;
    if( memeql( u8, id, params.v.chatId ) ) {
      var pathbuf: [256]u8 = undefined;
      const slice = z.fmt.bufPrint( &pathbuf, "../data/chats/{s}.json", .{id} ) catch "";
      const contents = u.readFileCrypto( slice ) catch {
        return net.sendJson( r, .internal_server_error, ErrRes{ .msg = "error reading file" } );
      }; defer alloc.free( contents );

      return net.sendJson( r, .ok, OkRes( .{ .name = file.name, .contents = contents } ) );
    }
  }

  return net.sendJson( r, .not_found, ErrRes{ .msg = "chat not found" } );
}

///route @/delete-chat
fn deleteChat( r: Request ) void {
  if( net.handleInvalidPostReq( r ) ) return;
  u.checkDbOnThread() catch return;

  const uuid = u.uuidFromApiOrAuthToken( r ) catch return;
  defer alloc.free( uuid );

  const params = u.jsonParse( GetChatReq, r.body.? ) catch {
    return net.sendJson( r, .bad_request, ErrRes{ .msg = "invalid request format" } );
  }; defer params.deinit();

  var userdata = u.getSettings( uuid ) catch {
    return net.sendJson( r, .internal_server_error, ErrRes{ .msg = "user not found" } );
  }; defer userdata.db_entry.?.deinit();

  const chats = userdata.chat_files;
  if( chats == null or chats.?.files == null )
    return net.sendJson( r, .not_found, ErrRes{ .msg = "chat not found" } );

  var updated_list = ArrayList( u.ChatEntry ).init( alloc );
  defer updated_list.deinit();

  var found = false;
  for( chats.?.files.? ) |file| {
    const id = file.id;
    if( memeql( u8, id, params.v.chatId ) ) {
      var pathbuf: [256]u8 = undefined;
      const slice = z.fmt.bufPrint( &pathbuf, "../data/chats/{s}.json", .{id} ) catch "";
      if( !u.fileExists( slice ) ) {
        found = true; continue;
      }

      u.deleteFile( slice ) catch continue;
      found = true;
    }
    else {
      updated_list.append( file ) catch {};
    }
  }

  if( found ) {
    userdata.chat_files.?.files = updated_list.items;
    u.updateSettings( &userdata ) catch {
      return net.sendJson( r, .internal_server_error, ErrRes{ .msg = "error updating user data" } );
    };

    return net.sendJson( r, .ok, OkRes( .{} ) );
  }

  return net.sendJson( r, .not_found, ErrRes{ .msg = "chat not found" } );
}

///route @/get-chat-name
fn getChatName( r: Request ) void {
  if( net.handleInvalidPostReq( r ) ) return;
  u.checkDbOnThread() catch return;

  const uuid = u.uuidFromApiOrAuthToken( r ) catch return;
  defer alloc.free( uuid );

  const params = u.jsonParse( GetChatReq, r.body.? ) catch {
    return net.sendJson( r, .bad_request, ErrRes{ .msg = "invalid request format" } );
  }; defer params.deinit();

  const userdata = u.getSettings( uuid ) catch {
    return net.sendJson( r, .internal_server_error, ErrRes{ .msg = "user not found" } );
  }; defer userdata.db_entry.?.deinit();

  const chats = userdata.chat_files;
  if( chats == null or chats.?.files == null )
    return net.sendJson( r, .not_found, ErrRes{ .msg = "chat not found" } );

  for( chats.?.files.? ) |file| {
    const id = file.id;
    if( memeql( u8, id, params.v.chatId ) ) {
      return net.sendJson( r, .ok, OkRes( .{ .name = file.name } ) );
    }
  }

  return net.sendJson( r, .not_found, ErrRes{ .msg = "file not found" } );
}