//  Copyright 2021 Aaron Hance
//
//  Licensed under the Apache License, Version 2.0 (the "License");
//  you may not use this file except in compliance with the License.
//  You may obtain a copy of the License at
//
//  http://www.apache.org/licenses/LICENSE-2.0
//
//  Unless required by applicable law or agreed to in writing, software
//  distributed under the License is distributed on an "AS IS" BASIS,
//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//  See the License for the specific language governing permissions and
//  limitations under the License.

{
    Driver->Storage->VolumeManager Drive volume manager

    @author(Aaron Hance ah@aaronhance.me)
}
unit volumemanager;

interface

uses
    util, 
    console,
    terminal,
    strings,
    lists,
    tracer,
    lmemorymanager,
    vfs,
    MBR,
    storagetypes;

type
    
    TDirectory_Entry_Type = (directoryEntry, fileEntry, mountEntry);

    PDirectory_Entry = ^TDirectory_Entry;
    PFilesystem = ^TFilesystem;
    PStorage_Volume = ^TStorage_Volume;

    PPWriteHook = procedure(volume : PStorage_volume; directory : pchar; entry : PDirectory_Entry; byteCount : uint32; buffer : puint32; statusOut : puint32);
    PPReadHook = function(volume : PStorage_Volume; directory : pchar; fileName : pchar; fileExtension : pchar; buffer : puint32; bytecount : puint32) : uint32;
    PPHIOHook = procedure(volume : PStorage_device; addr : uint32; sectors : uint32; buffer : puint32);
    PPCreateHook = procedure(disk : PStorage_Device; sectors : uint32; start : uint32; config : puint32);
    PPDetectHook = procedure(disk : PStorage_Device);
    PPCreateDirHook = procedure(volume : PStorage_volume; directory : pchar; dirname : pchar; attributes : uint32; status : puint32);
    PPReadDirHook = function(volume : PStorage_volume; directory : pchar; status : puint32) : PLinkedListBase; //returns: 0 = success, 1 = dir not exsist, 2 = not directory, 3 = error //returns: 0 = success, 1 = dir not exsist, 2 = not directory, 3 = error

    PPHIOHook_ = procedure;

    TFilesystem = record
        sName : pchar;
        system_id : uint8;
        writeCallback     : PPWriteHook;
        readCallback      : PPReadHook;
        createCallback    : PPCreateHook;
        detectCallback    : PPDetectHook;
        createDirCallback : PPCreateDirHook;
        readDirCallback   : PPReadDirHook;
    end;

    TStorage_Volume = record
        device          : PStorage_device;
        sectorStart     : uint32;
        sectorSize      : uint32;
        sectorCount     : uint32;
        freeSectors     : uint32;
        filesystem      : PFilesystem; 
        { True if this drive contains the loaded OS }
        isBootDrive     : boolean;
    end;

    { Generic directory entry }
    TDirectory_Entry = record
        { Contains filename and optionally file extension, seperated by the last period.}
        fileName  : pchar; 
        entryType : TDirectory_Entry_Type;
        // creationT : TDateTime;
        // modifiedT : TDateTime;
    end;
  
var

    storageVolumes : PLinkedListBase;
    filesystems : PlinkedListBase;

    procedure init();
    
    procedure register_filesystem(filesystem : PFilesystem);
    procedure check_for_volumes(drive : PStorage_device);

    //IO functions

implementation

procedure list_volume_command();
var 
    i : uint32; 
    volume : PStorage_Volume;
begin
  push_trace('VolumeManager.list_volume_command');

  if LL_Size(storageVolumes) < 1 then begin
      console.writestringlnWnd('No volumes found.', getTerminalHWND());
      exit;
  end;

  console.writestringlnWnd('Volumes: ', getTerminalHWND());

  for i:=0 to LL_Size(storageVolumes) - 1 do begin
      volume := PStorage_Volume(LL_Get(storageVolumes, i));

      console.writestringWnd('  ', getTerminalHWND());
      console.writeintWnd(i, getTerminalHWND());
      console.writestringWnd(' - Capacity: ', getTerminalHWND());
      console.writeintWnd(uint32(volume^.sectorSize * volume^.sectorCount DIV 1024 DIV 1024), getTerminalHWND());
      console.writestringWnd('MB System: ', getTerminalHWND());
      console.writestringlnWnd(volume^.filesystem^.sName, getTerminalHWND());
  end;
end;

procedure volume_command(params : PParamList);
var
    i : uint16;
    subcmd : pchar;
begin
    push_trace('VolumeManager.volume_command');
    subcmd:= getParam(0, params);

    if ((paramCount(params) = 0)) then begin
        console.writestringlnWnd('Please provide valid arguments.', getTerminalHWND());
        console.writestringlnWnd('  ls - for listing all volumes', getTerminalHWND());
        console.writestringlnWnd('  lsfs - for listing all filesystems', getTerminalHWND());
        console.writestringlnWnd('  info [volume] - display formation for specified volume', getTerminalHWND());
        console.writestringlnWnd('  format [volume] [filesystem] - destructive, formats a volume with a specified filesystem', getTerminalHWND());
        exit;
    end;

    if( stringEquals(subcmd, 'ls') ) then begin
      list_volume_command();
      exit;
    end;
end;

{ Initialise volume manager }
procedure init();
begin
    push_trace('VolumeManager.init');

    { setup lists }
    storageVolumes:= ll_New(sizeof(TFilesystem));
    filesystems:= ll_New(sizeof(TFilesystem));   

    terminal.registerCommand('volume', @volume_command, 'Volume utility');   
end;

{ register a new type of filesystem }
procedure register_filesystem(filesystem : PFilesystem); //TODO on init create null filesystem for empty partition
var
    elm : void;
begin
    //add filesystem
    elm := LL_add(filesystems);
    memcpy(uint32(filesystem), uInt32(elm), SizeOf(TFilesystem));

    //check drives for volumes of new type
end;

{ Check for volumes on a physical device }
procedure check_for_volumes(drive : PStorage_device);
var 
    bootrecord : PMaster_Boot_Record;
    storageVolume : TStorage_Volume;
    i : uint32 = 0;
    elm : void;
begin
    push_trace('VolumeManager.check_for_volumes');

    bootrecord := PMaster_Boot_Record(kalloc(SizeOf(TMaster_Boot_Record)));
    drive^.readCallback(drive, 0, 1, puint32(bootrecord));

    //TODO multipe partition entries
    if bootrecord^.partition_0.LBA_start <> 0 then
    begin
      //set volume information
      storageVolume.device := drive;
      storageVolume.sectorStart := bootrecord^.partition_0.LBA_start;
      storageVolume.sectorCount := bootrecord^.partition_0.sector_count;
      storageVolume.freeSectors := 0; //TODO impliment
    push_trace('VolumeManager.init2');

      if LL_Size(filesystems) < 1 then begin
        console.writestringln('Failed to initalise storage system, no filesystems found, stopping!');
        exit;
      end;

      //check for filesystem type
      for i:=0 to LL_Size(filesystems) - 1 do begin
        if bootrecord^.partition_0.system_id = PFilesystem(LL_Get(filesystems, i))^.system_id then
        begin
          storageVolume.filesystem := PFilesystem(LL_Get(filesystems, i));
        end;
      end;
    push_trace('VolumeManager.init3');

      //add volume to list
      elm := LL_Add(storageVolumes);
      memcpy(uint32(@storageVolume), uint32(elm), SizeOf(TStorage_Volume));
            push_trace('VolumeManager.init4');

      elm := LL_Add(drive^.volumes);
      memcpy(uint32(@storageVolume), uint32(elm), SizeOf(TStorage_Volume));

    end;
    
end;

end.