unit UWriter;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, UFilter, Math, crt, fgl;

type
  TWriter = class
  public
    procedure WriteContent(AContent: String; AFilters: TFilterList;
      AGroupRanges: TGroupRanges); virtual; abstract;
  end;
  TWriterList = specialize TFPGObjectList<TWriter>;

  { TConsoleWriter }

  TConsoleWriter = class(TWriter)
  public
    procedure WriteContent(AContent: String; AFilters: TFilterList;
      AGroupRanges: TGroupRanges); override;
  end;

implementation

{ TConsoleWriter }

procedure TConsoleWriter.WriteContent(AContent: String; AFilters: TFilterList;
  AGroupRanges: TGroupRanges);
var
  i: Integer;
  matchPos, offset, lastPos: Integer;
  highlights: THighlights;
  highlight: THighlight;
  group: Byte;
begin
  highlights := THighlights.Create;

  offset := 0;
  lastPos := 1;

  for i := 0 to AFilters.Count - 1 do
  begin
    if AFilters[i].Expression.Exec(AContent) then
    begin
      repeat
        // We need these values anyway.
        matchPos := AFilters[i].Expression.MatchPos[0];
        offset := AFilters[i].Expression.MatchLen[0];

        group := AFilters[i].Group;
        if group < Length(AGroupRanges) then
        begin
          if (matchPos + offset < AGroupRanges[group].StartIdx) or
            (matchPos > AGroupRanges[group].EndIdx) then
            continue; //Pointless; nothing we can do here

          highlight.Start := Max(AGroupRanges[group].StartIdx, matchPos);
          highlight.Length := Min(AGroupRanges[group].EndIdx - highlight.Start,
            highlight.Start + offset - matchPos);

          {$ifdef debugmatches}
          writeln('  Highlight: ', highlight.Start, ', ', highlight.Length);
          writeln('    MatchPos: ', matchPos, ', StartIdx: ', AGroupRanges[group].StartIdx);
          writeln('    Offset: ', offset, ', EndIdx: ', AGroupRanges[group].EndIdx);
          {$endif}
        end else
        begin
          highlight.Start := matchPos;
          highlight.Length := offset;
        end;

        highlight.FGColor := AFilters[i].FGColor;
        highlight.BGColor := AFilters[i].BGColor;
        highlights.Add(highlight);
      until not AFilters[i].Expression.ExecNext;
    end;
  end;

  highlights.Sort(@CompareHighlights);

  // Sanitize highlights
  for i := 0 to highlights.Count - 2 do
  begin
    if (highlights[i].Start + highlights[i].Length) > highlights[i+1].Start then
    begin
      highlight := highlights[i];
      highlight.Length := highlights[i+1].Start - highlights[i].Start;
      highlights[i] := highlight;
    end;
  end;

  for highlight in highlights do
  begin
    matchPos := highlight.Start;
    offset := highlight.Length;
    write(Copy(AContent, lastPos, matchPos - lastPos));
    if highlight.FGColor < $FF then
      TextColor(highlight.FGColor);
    if highlight.BGColor < $FF then
      TextBackground(highlight.BGColor);
    write(Copy(AContent, matchPos, offset));
    NormVideo;
    lastPos := matchPos + offset;
  end;

  writeln(Copy(AContent, lastPos, Length(AContent)));

  highlights.Free;
end;

end.