{
    This file is part of the Pas2JS run time library.
    Copyright (c) 2023 by Michael Van Canneyt
    
    Low-level Pas2JS resource handling.

    See the file COPYING.FPC, included in this distribution,
    for details about the copyright.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

 **********************************************************************}
{$IFNDEF FPC_DOTTEDUNITS}
unit p2jsres;
{$ENDIF}

{$mode objfpc}
{$h+}
{$modeswitch externalclass}

interface

{$IFDEF FPC_DOTTEDUNITS}
uses System.Types;
{$ELSE}
uses types;
{$ENDIF}

Type
  TResourceSource = (rsJS,rsHTML);
  TResourceInfo = record
    name : string;
    encoding : string;
    resourceunit : string;
    format : string;
    data : string;
  end;
  TResourceEnumCallBack = Reference to function(const resName : string) : boolean;
  TResourcesLoadedEnumCallBack = Reference to Procedure(const LoadedResources : Array of String);
  TResourcesLoadErrorCallBack = Reference to Procedure(const aError : string);

Function SetResourceSource(aSource : TResourceSource) : TResourceSource;

Function GetResourceNames : TStringDynArray;
Function GetResourceNames(aSource : TResourceSource) : TStringDynArray;

Function EnumResources(aCallback : TResourceEnumCallBack) : Integer;
Function EnumResources(aSource : TResourceSource; aCallback : TResourceEnumCallBack) : Integer;

Function GetResourceInfo(Const aName : String; var aInfo : TResourceInfo) : Boolean;
Function GetResourceInfo(aSource : TResourceSource; Const aName : String; var aInfo : TResourceInfo) : Boolean;

Procedure LoadHTMLLinkResources(const aURL : String; OnLoad : TResourcesLoadedEnumCallBack = Nil; OnError : TResourcesLoadErrorCallBack = Nil);

implementation

Uses
{$IFDEF FPC_DOTTEDUNITS}
 System.SysUtils, JSApi.JS, BrowserApi.Web;
{$ELSE}
 sysutils, js, web;
{$ENDIF}

var
  gMode: TResourceSource;

{ ---------------------------------------------------------------------
  Global entry points
  ---------------------------------------------------------------------}

Function SeTResourceSource(aSource : TResourceSource) : TResourceSource;
begin
  Result:=gMode;
  gMode:=aSource;
end;

Function GetResourceNames : TStringDynArray;
begin
  Result:=GetResourceNames(gMode);
end;

Function EnumResources(aCallback : TResourceEnumCallBack) : Integer;

begin
  Result:=EnumResources(gMode,aCallback);
end;

Function GetResourceInfo(Const aName : String; var aInfo : TResourceInfo) : Boolean;

begin
  Result:=GetResourceInfo(gMode,aName,aInfo);
end;

{ ---------------------------------------------------------------------
  JS resources
  ---------------------------------------------------------------------}

Type
  TRTLResourceInfo = class external name 'Object' (TJSObject)
    name : string;
    encoding : string;
    resourceunit : string; external name 'unit';
    format : string;
    data : string;
  end;

function rtlGetResourceList : TStringDynArray; external name 'rtl.getResourceList';
function rtlGetResource(const aName : string) : TRTLResourceInfo; external name 'rtl.getResource';

Function GetRTLResourceInfo(Const aName : String; var aInfo : TResourceInfo) : Boolean;

Var
  RTLInfo : TRTLResourceInfo;

begin
  RTLInfo:=rtlGetResource(lowercase(aName));
  Result:=Assigned(RTLInfo);
  if Result then
    begin
    aInfo.name:=RTLinfo.name;
    aInfo.encoding:=RTLinfo.encoding;
    aInfo.format:=RTLinfo.format;
    aInfo.resourceunit:=RTLinfo.resourceunit;
    aInfo.data:=RTLinfo.data;
    end;
end;

{ ---------------------------------------------------------------------
  HTML resources
  ---------------------------------------------------------------------}

Const
  IDPrefix = 'resource-';

Function IsResourceLink(L : TJSHTMLLinkElement) : Boolean;

begin
  Result:=(Copy(L.id,1,Length(IDPrefix))=IDPrefix) and (isDefined(L.Dataset['unit'])) and (Copy(L.href,1,4)='data')
end;

Function GetHTMLResources : TStringDynArray;


Var
  LC : TJSHTMLCollection;
  L : TJSHTMLLinkElement;
  I : Integer;
  ID : String;

begin
  SetLength(Result,0);
  if not isDefined(document) then // If called in Node...
    exit;
  // No cache, we do this dynamically: it's possible to add link nodes at runtime.
  LC:=document.getElementsByTagName('link');
  For I:=0 to LC.length-1 do
    begin
    L:=TJSHTMLLinkElement(LC[i]);
    ID:=L.ID;
    if IsResourceLink(L) then
      begin
      Delete(ID,1,Length(IDPrefix));
      if (ID<>'') then
        TJSArray(Result).Push(ID);
      end;
    end;
end;

Function GetHTMLResourceInfo(Const aName : String; var aInfo : TResourceInfo) : Boolean;

Var
  el : TJSElement;
  L : TJSHTMLLinkElement absolute el;
  S : String;
  I : Integer;

begin
  Result:=False;
  if not isDefined(document) then // If called in Node...
    exit;
  El:=document.getElementByID(IDPrefix+lowercase(aName));
  Result:=assigned(el) and SameText(el.tagName,'link');
  if not Result then
    exit;
  ainfo.name:=lowercase(aName);
  ainfo.Resourceunit:=String(L.Dataset['unit']);
  S:=L.href;
  S:=Copy(S,6,Length(S)-5); // strip data;
  I:=Pos(',',S);
  aInfo.data:=Copy(S,I+1,Length(S)-1);
  S:=copy(S,1,I-1);
  I:=Pos(';',S);
  if I=0 then
    aInfo.encoding:=''
  else
    begin
    aInfo.encoding:=Copy(S,I+1,Length(S)-1);
    S:=Copy(S,1,I-1);
    end;
  aInfo.Format:=S;
end;

Function HasTemplate : Boolean;

begin
  asm
    return ('content' in document.createElement('template'))
  end;
  Result:=false;
end;


Procedure LoadHTMLLinkResources(const aURL : String; OnLoad : TResourcesLoadedEnumCallBack = Nil; OnError : TResourcesLoadErrorCallBack = Nil);

  function FetchOK(Res : JSValue) : JSValue;
  var
    Response : TJSResponse absolute res;
  begin
    Result:=Nil;
    if not Response.ok then
      begin
      if Assigned(OnError) then
        Raise TJSError.New('HTTP Error for URL aURL, status = '+IntToStr(Response.status)+' : '+Response.statusText)
      end
    else
      Result:=Response.Text();
  end;

  function BlobOK(Res : JSValue) : JSValue;

  Var
    aText : String absolute res;
    ID : String;
    Tmpl : TJSHTMLTemplateElement;
    El : TJSHTMLElement;
    L : TJSHTMLLinkElement absolute El;
    Arr : TStringDynArray;
    aParent : TJSHTMLElement;

  begin
    Result:=Nil;
    aParent:=TJSHTMLElement(document.head);
    if aParent=Nil then
      aParent:=TJSHTMLElement(document.body);
    SetLength(Arr,0);
    Tmpl:=TJSHTMLTemplateElement(Document.createElement('template'));
    Tmpl.innerhtml:=TJSString(aText).trim;
    el:=TJSHTMLElement(Tmpl.Content.firstElementChild);
    While El<>Nil do
      begin
      if SameText(El.tagName,'link') and IsResourceLink(L) then
        begin
        aParent.Append(TJSHTMLElement(document.importNode(l,true)));
        ID:=L.ID;
        Delete(ID,1,Length(IDPrefix));
        if (ID<>'') then
          TJSArray(Arr).Push(ID);
        end;
      el:=TJSHTMLElement(el.nextElementSibling);
      end;
    if Assigned(OnLoad) then
      OnLoad(Arr);
  end;

  function DoError (aValue : JSValue) : JSValue;

  Var
    aErr : TJSError absolute aValue;

  begin
    Result:=Nil;
    if Assigned(OnError) then
      if aErr=Nil then
        OnError('Error: ' + aErr.message)
  end;

begin
  if not HasTemplate then
    begin
    if Assigned(OnError) then
      OnError('No template support in this browser')
    end
  else
    window.fetch(aURL)._then(@FetchOK)._then(@BlobOK).catch(@doError);
end;


{ ---------------------------------------------------------------------
  Global entries, specifying resource mode
  ---------------------------------------------------------------------}

Function GetResourceNames(aSource : TResourceSource) : TStringDynArray;

begin
  case aSource of
    rsJS : Result:=rtlGetResourceList;
    rsHTML : Result:=GetHTMLResources;
  end;
end;

Function EnumResources(aSource : TResourceSource; aCallback : TResourceEnumCallBack) : Integer;

Var
  RL : TStringDynArray;
  I : Integer;
  ContinueEnum : Boolean;

begin
  Result:=0;
  RL:=GetResourceNames(aSource);
  I:=0;
  Result:=Length(RL);
  ContinueEnum:=True;
  While (I<Result) and ContinueEnum do
    begin
    ContinueEnum:=aCallBack(RL[i]);
    Inc(I);
    end;
end;


Function GetResourceInfo(aSource : TResourceSource; Const aName : String; var aInfo : TResourceInfo) : Boolean;

begin
  case aSource of
    rsJS : Result:=GetRTLResourceInfo(aName,aInfo);
    rsHTML : Result:=GetHTMLResourceInfo(aName,aInfo);
  end;
end;


end.