/*
 * Copyright (C) 2009-2015 Canonical Ltd.
 * Author: Robert Ancell <robert.ancell@canonical.com>
 *
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version. See http://www.gnu.org/copyleft/gpl.html the full text of the
 * license.
 */

public class Book
{
    private List<Page> pages;

    public uint n_pages { get { return pages.length (); } }

    private bool needs_saving_;
    public bool needs_saving
    {
        get { return needs_saving_; }
        set
        {
            if (needs_saving_ == value)
                return;
            needs_saving_ = value;
            needs_saving_changed ();
        }
    }

    public signal void page_added (Page page);
    public signal void page_removed (Page page);
    public signal void reordered ();
    public signal void cleared ();
    public signal void needs_saving_changed ();
    public signal void saving (int i);

    public Book ()
    {
        pages = new List<Page> ();
    }

    ~Book ()
    {
        foreach (var page in pages)
        {
            page.pixels_changed.disconnect (page_changed_cb);
            page.crop_changed.disconnect (page_changed_cb);
        }
    }

    public void clear ()
    {
        foreach (var page in pages)
        {
            page.pixels_changed.disconnect (page_changed_cb);
            page.crop_changed.disconnect (page_changed_cb);
        }
        pages = null;
        cleared ();
    }

    private void page_changed_cb (Page page)
    {
        needs_saving = true;
    }

    public void append_page (Page page)
    {
        page.pixels_changed.connect (page_changed_cb);
        page.crop_changed.connect (page_changed_cb);

        pages.append (page);
        page_added (page);
        needs_saving = true;
    }

    public void move_page (Page page, uint location)
    {
        pages.remove (page);
        pages.insert (page, (int) location);
        reordered ();
        needs_saving = true;
    }

    public void reverse ()
    {
        var new_pages = new List<Page> ();
        foreach (var page in pages)
            new_pages.prepend (page);
        pages = (owned) new_pages;

        reordered ();
        needs_saving = true;
    }

    public void combine_sides ()
    {
        var n_front = n_pages - n_pages / 2;
        var new_pages = new List<Page> ();
        for (var i = 0; i < n_pages; i++)
        {
            if (i % 2 == 0)
                new_pages.append (pages.nth_data (i / 2));
            else
                new_pages.append (pages.nth_data (n_front + (i / 2)));
        }
        pages = (owned) new_pages;

        reordered ();
        needs_saving = true;
    }

    public void combine_sides_reverse ()
    {
        var new_pages = new List<Page> ();
        for (var i = 0; i < n_pages; i++)
        {
            if (i % 2 == 0)
                new_pages.append (pages.nth_data (i / 2));
            else
                new_pages.append (pages.nth_data (n_pages - 1 - (i / 2)));
        }
        pages = (owned) new_pages;

        reordered ();
        needs_saving = true;
    }

    public void delete_page (Page page)
    {
        page.pixels_changed.disconnect (page_changed_cb);
        page.crop_changed.disconnect (page_changed_cb);
        pages.remove (page);
        page_removed (page);
        needs_saving = true;
    }

    public Page get_page (int page_number)
    {
        if (page_number < 0)
            page_number = (int) pages.length () + page_number;
        return pages.nth_data (page_number);
    }

    public uint get_page_index (Page page)
    {
        return pages.index (page);
    }

    private File make_indexed_file (string uri, int i)
    {
        if (n_pages == 1)
            return File.new_for_uri (uri);

        /* Insert index before extension */
        var basename = Path.get_basename (uri);
        string prefix = uri, suffix = "";
        var extension_index = basename.last_index_of_char ('.');
        if (extension_index >= 0)
        {
            suffix = basename.slice (extension_index, basename.length);
            prefix = uri.slice (0, uri.length - suffix.length);
        }
        var width = n_pages.to_string().length;
        var number_format = "%%0%dd".printf (width);
        var filename = prefix + "-" + number_format.printf (i + 1) + suffix;
        return File.new_for_uri (filename);
    }

    private void save_multi_file (string type, int quality, File file) throws Error
    {
        for (var i = 0; i < n_pages; i++)
        {
            var page = get_page (i);
            page.save (type, quality, make_indexed_file (file.get_uri (), i));
            saving (i);
        }
    }

    private void save_ps_pdf_surface (Cairo.Surface surface, Gdk.Pixbuf image, double dpi)
    {
        var context = new Cairo.Context (surface);
        context.scale (72.0 / dpi, 72.0 / dpi);
        Gdk.cairo_set_source_pixbuf (context, image, 0, 0);
        context.get_source ().set_filter (Cairo.Filter.BEST);
        context.paint ();
    }

    private void save_ps (File file) throws Error
    {
        var stream = file.replace (null, false, FileCreateFlags.NONE, null);
        var writer = new PsWriter (stream);
        var surface = writer.surface;

        for (var i = 0; i < n_pages; i++)
        {
            var page = get_page (i);
            var image = page.get_image (true);
            var width = image.width * 72.0 / page.dpi;
            var height = image.height * 72.0 / page.dpi;
            surface.set_size (width, height);
            save_ps_pdf_surface (surface, image, page.dpi);
            surface.show_page ();
            saving (i);
        }
    }

    private uint8[]? compress_zlib (uint8[] data)
    {
        var stream = ZLib.DeflateStream (ZLib.Level.BEST_COMPRESSION);
        var out_data = new uint8[data.length];

        stream.next_in = data;
        stream.next_out = out_data;
        while (stream.avail_in > 0)
        {
            if (stream.deflate (ZLib.Flush.FINISH) == ZLib.Status.STREAM_ERROR)
                break;
        }

        if (stream.avail_in > 0)
            return null;

        var n_written = data.length - stream.avail_out;
        out_data.resize ((int) n_written);

        return out_data;
    }

    private ByteArray jpeg_data;

    private uint8[] compress_jpeg (Gdk.Pixbuf image, int quality, int dpi)
    {
        jpeg_data = new ByteArray ();
        string[] keys = { "quality", "density-unit", "x-density", "y-density", null };
        string[] values = { "%d".printf (quality), "dots-per-inch", "%d".printf (dpi), "%d".printf (dpi), null };
        try
        {
            image.save_to_callbackv (write_pixbuf_data, "jpeg", keys, values);
        }
        catch (Error e)
        {
        }
        var data = (owned) jpeg_data.data;
        jpeg_data = null;

        return data;
    }

    private bool write_pixbuf_data (uint8[] buf) throws Error
    {
        jpeg_data.append (buf);
        return true;
    }

    private void save_pdf (File file, int quality) throws Error
    {
        /* Generate a random ID for this file */
        var id = "";
        for (var i = 0; i < 4; i++)
            id += "%08x".printf (Random.next_int ());

        var stream = file.replace (null, false, FileCreateFlags.NONE, null);
        var writer = new PDFWriter (stream);

        /* Choose object numbers */
        var catalog_number = writer.add_object ();
        var metadata_number = writer.add_object ();
        var pages_number = writer.add_object ();
        var info_number = writer.add_object ();
        var page_numbers = new uint[n_pages];
        var page_image_numbers = new uint[n_pages];
        var page_content_numbers = new uint[n_pages];
        for (var i = 0; i < n_pages; i++)
        {
            page_numbers[i] = writer.add_object ();
            page_image_numbers[i] = writer.add_object ();
            page_content_numbers[i] = writer.add_object ();
        }
        var struct_tree_root_number = writer.add_object ();

        /* Header */
        writer.write_string ("%PDF-1.3\n");

        /* Comment with binary as recommended so file is treated as binary */
        writer.write_string ("%\xe2\xe3\xcf\xd3\n");

        /* Catalog */
        writer.start_object (catalog_number);
        writer.write_string ("%u 0 obj\n".printf (catalog_number));
        writer.write_string ("<<\n");
        writer.write_string ("/Type /Catalog\n");
        writer.write_string ("/Metadata %u 0 R\n".printf (metadata_number));
        writer.write_string ("/MarkInfo << /Marked true >>\n");
        writer.write_string ("/StructTreeRoot %u 0 R\n".printf (struct_tree_root_number));
        writer.write_string ("/Pages %u 0 R\n".printf (pages_number));
        writer.write_string (">>\n");
        writer.write_string ("endobj\n");

        /* Metadata */
        var now = new DateTime.now_local ();
        var date_string = now.format ("%FT%H:%M:%S%:z");
        /* NOTE: The id has to be hardcoded to this value according to the spec... */
        var metadata = """<?xpacket begin="%s" id="W5M0MpCehiHzreSzNTczkc9d"?>
<rdf:RDF xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#"
         xmlns:xmp="http://ns.adobe.com/xap/1.0/">
  <rdf:Description rdf:about=""
                   xmlns:pdfaid="http://www.aiim.org/pdfa/ns/id/"
                   xmlns:xmp="http://ns.adobe.com/xap/1.0/">
    <pdfaid:part>1</pdfaid:part>
    <pdfaid:conformance>A</pdfaid:conformance>
    <xmp:CreatorTool>Simple Scan %s</xmp:CreatorTool>
    <xmp:CreateDate>%s</xmp:CreateDate>
    <xmp:ModifyDate>%s</xmp:ModifyDate>
    <xmp:MetadataDate>%s</xmp:MetadataDate>
  </rdf:Description>
</rdf:RDF>
<?xpacket end="w"?>""".printf (((unichar) 0xFEFF).to_string (), VERSION, date_string, date_string, date_string);
        writer.write_string ("\n");
        writer.start_object (metadata_number);
        writer.write_string ("%u 0 obj\n".printf (metadata_number));
        writer.write_string ("<<\n");
        writer.write_string ("/Type /Metadata\n");
        writer.write_string ("/Subtype /XML\n");
        writer.write_string ("/Length %u\n".printf (metadata.length));
        writer.write_string (">>\n");
        writer.write_string ("stream\n");
        writer.write_string (metadata);
        writer.write_string ("\n");
        writer.write_string ("endstream\n");
        writer.write_string ("endobj\n");

        /* Pages */
        writer.write_string ("\n");
        writer.start_object (pages_number);
        writer.write_string ("%u 0 obj\n".printf (pages_number));
        writer.write_string ("<<\n");
        writer.write_string ("/Type /Pages\n");
        writer.write_string ("/Kids [");
        for (var i = 0; i < n_pages; i++)
            writer.write_string (" %u 0 R".printf (page_numbers[i]));
        writer.write_string (" ]\n");
        writer.write_string ("/Count %u\n".printf (n_pages));
        writer.write_string (">>\n");
        writer.write_string ("endobj\n");

        for (var i = 0; i < n_pages; i++)
        {
            var page = get_page (i);
            var image = page.get_image (true);
            var width = image.width;
            var height = image.height;
            unowned uint8[] pixels = image.get_pixels ();
            var page_width = width * 72.0 / page.dpi;
            var page_height = height * 72.0 / page.dpi;

            int depth = 8;
            string color_space = "DeviceRGB";
            string? filter = null;
            char[] width_buffer = new char[double.DTOSTR_BUF_SIZE];
            char[] height_buffer = new char[double.DTOSTR_BUF_SIZE];
            uint8[] data;
            if (page.is_color)
            {
                depth = 8;
                color_space = "DeviceRGB";
                var data_length = height * width * 3;
                data = new uint8[data_length];
                for (var row = 0; row < height; row++)
                {
                    var in_offset = row * image.rowstride;
                    var out_offset = row * width * 3;
                    for (var x = 0; x < width; x++)
                    {
                        var in_o = in_offset + x*3;
                        var out_o = out_offset + x*3;

                        data[out_o] = pixels[in_o];
                        data[out_o+1] = pixels[in_o+1];
                        data[out_o+2] = pixels[in_o+2];
                    }
                }
            }
            else if (page.depth == 2)
            {
                int shift_count = 6;
                depth = 2;
                color_space = "DeviceGray";
                var data_length = height * ((width * 2 + 7) / 8);
                data = new uint8[data_length];
                var offset = 0;
                for (var row = 0; row < height; row++)
                {
                    /* Pad to the next line */
                    if (shift_count != 6)
                    {
                        offset++;
                        shift_count = 6;
                    }

                    var in_offset = row * image.rowstride;
                    for (var x = 0; x < width; x++)
                    {
                        /* Clear byte */
                        if (shift_count == 6)
                            data[offset] = 0;

                        /* Set bits */
                        var p = pixels[in_offset + x*3];
                        if (p >= 192)
                            data[offset] |= 3 << shift_count;
                        else if (p >= 128)
                            data[offset] |= 2 << shift_count;
                        else if (p >= 64)
                            data[offset] |= 1 << shift_count;

                        /* Move to the next position */
                        if (shift_count == 0)
                        {
                            offset++;
                            shift_count = 6;
                        }
                        else
                            shift_count -= 2;
                    }
                }
            }
            else if (page.depth == 1)
            {
                int mask = 0x80;

                depth = 1;
                color_space = "DeviceGray";
                var data_length = height * ((width + 7) / 8);
                data = new uint8[data_length];
                var offset = 0;
                for (var row = 0; row < height; row++)
                {
                    /* Pad to the next line */
                    if (mask != 0x80)
                    {
                        offset++;
                        mask = 0x80;
                    }

                    var in_offset = row * image.rowstride;
                    for (var x = 0; x < width; x++)
                    {
                        /* Clear byte */
                        if (mask == 0x80)
                            data[offset] = 0;

                        /* Set bit */
                        if (pixels[in_offset+x*3] != 0)
                            data[offset] |= (uint8) mask;

                        /* Move to the next bit */
                        mask >>= 1;
                        if (mask == 0)
                        {
                            offset++;
                            mask = 0x80;
                        }
                    }
                }
            }
            else
            {
                depth = 8;
                color_space = "DeviceGray";
                var data_length = height * width;
                data = new uint8 [data_length];
                for (var row = 0; row < height; row++)
                {
                    var in_offset = row * image.rowstride;
                    var out_offset = row * width;
                    for (var x = 0; x < width; x++)
                        data[out_offset+x] = pixels[in_offset+x*3];
                }
            }

            /* Compress data */
            var compressed_data = compress_zlib (data);
            if (compressed_data != null)
            {
                /* Try if JPEG compression is better */
                if (depth > 1)
                {
                    var jpeg_data = compress_jpeg (image, quality, page.dpi);
                    if (jpeg_data.length < compressed_data.length)
                    {
                        filter = "DCTDecode";
                        data = jpeg_data;
                    }
                }

                if (filter == null)
                {
                    filter = "FlateDecode";
                    data = compressed_data;
                }
            }

            /* Page */
            writer.write_string ("\n");
            writer.start_object (page_numbers[i]);
            writer.write_string ("%u 0 obj\n".printf (page_numbers[i]));
            writer.write_string ("<<\n");
            writer.write_string ("/Type /Page\n");
            writer.write_string ("/Parent %u 0 R\n".printf (pages_number));
            writer.write_string ("/Resources << /XObject << /Im%d %u 0 R >> >>\n".printf (i, page_image_numbers[i]));
            writer.write_string ("/MediaBox [ 0 0 %s %s ]\n".printf (page_width.format (width_buffer, "%.2f"), page_height.format (height_buffer, "%.2f")));
            writer.write_string ("/Contents %u 0 R\n".printf (page_content_numbers[i]));
            writer.write_string (">>\n");
            writer.write_string ("endobj\n");

            /* Page image */
            writer.write_string ("\n");
            writer.start_object (page_image_numbers[i]);
            writer.write_string ("%u 0 obj\n".printf (page_image_numbers[i]));
            writer.write_string ("<<\n");
            writer.write_string ("/Type /XObject\n");
            writer.write_string ("/Subtype /Image\n");
            writer.write_string ("/Width %d\n".printf (width));
            writer.write_string ("/Height %d\n".printf (height));
            writer.write_string ("/ColorSpace /%s\n".printf (color_space));
            writer.write_string ("/BitsPerComponent %d\n".printf (depth));
            writer.write_string ("/Length %d\n".printf (data.length));
            if (filter != null)
                writer.write_string ("/Filter /%s\n".printf (filter));
            writer.write_string (">>\n");
            writer.write_string ("stream\n");
            writer.write (data);
            writer.write_string ("\n");
            writer.write_string ("endstream\n");
            writer.write_string ("endobj\n");

            /* Structure tree */
            writer.write_string ("\n");
            writer.start_object (struct_tree_root_number);
            writer.write_string ("%u 0 obj\n".printf (struct_tree_root_number));
            writer.write_string ("<<\n");
            writer.write_string ("/Type /StructTreeRoot\n");            
            writer.write_string (">>\n");
            writer.write_string ("endobj\n");

            /* Page contents */
            var command = "q\n%s 0 0 %s 0 0 cm\n/Im%d Do\nQ".printf (page_width.format (width_buffer, "%f"), page_height.format (height_buffer, "%f"), i);
            writer.write_string ("\n");
            writer.start_object (page_content_numbers[i]);
            writer.write_string ("%u 0 obj\n".printf (page_content_numbers[i]));
            writer.write_string ("<<\n");
            writer.write_string ("/Length %d\n".printf (command.length));
            writer.write_string (">>\n");
            writer.write_string ("stream\n");
            writer.write_string (command);
            writer.write_string ("\n");
            writer.write_string ("endstream\n");
            writer.write_string ("endobj\n");

            saving (i);
        }

        /* Info */
        writer.write_string ("\n");
        writer.start_object (info_number);
        writer.write_string ("%u 0 obj\n".printf (info_number));
        writer.write_string ("<<\n");
        writer.write_string ("/Creator (Simple Scan %s)\n".printf (VERSION));
        writer.write_string (">>\n");
        writer.write_string ("endobj\n");

        /* Cross-reference table */
        writer.write_string ("\n");
        var xref_offset = writer.offset;
        writer.write_string ("xref\n");
        writer.write_string ("0 %zu\n".printf (writer.object_offsets.length + 1));
        writer.write_string ("%010zu 65535 f \n".printf (next_empty_object (writer, 0)));
        for (var i = 0; i < writer.object_offsets.length; i++)
            if (writer.object_offsets[i] == 0)
                writer.write_string ("%010zu 65535 f \n".printf (next_empty_object (writer, i + 1)));
            else
                writer.write_string ("%010zu 00000 n \n".printf (writer.object_offsets[i]));

        /* Trailer */
        writer.write_string ("\n");
        writer.write_string ("trailer\n");
        writer.write_string ("<<\n");
        writer.write_string ("/Size %zu\n".printf (writer.object_offsets.length + 1));
        writer.write_string ("/Info %u 0 R\n".printf (info_number));
        writer.write_string ("/Root %u 0 R\n".printf (catalog_number));
        writer.write_string ("/ID [<%s> <%s>]\n".printf (id, id));
        writer.write_string (">>\n");
        writer.write_string ("startxref\n");
        writer.write_string ("%zu\n".printf (xref_offset));
        writer.write_string ("%%EOF\n");
    }

    static int next_empty_object (PDFWriter writer, int start)
    {
        for (var i = start; i < writer.object_offsets.length; i++)
            if (writer.object_offsets[i] == 0)
                return i + 1;
        return 0;
    }

    public void save (string type, int quality, File file) throws Error
    {
        switch (type)
        {
        case "jpeg":
        case "png":
        case "tiff":
            save_multi_file (type, quality, file);
            break;
        case "ps":
            save_ps (file);
            break;
        case "pdf":
            save_pdf (file, quality);
            break;
        }
    }
}

private class PDFWriter
{
    public size_t offset = 0;
    public uint[] object_offsets;
    private FileOutputStream stream;

    public PDFWriter (FileOutputStream stream)
    {
        this.stream = stream;
        object_offsets = new uint[0];
    }

    public void write (uint8[] data)
    {
        try
        {
            stream.write_all (data, null, null);
        }
        catch (Error e)
        {
            warning ("Error writing PDF: %s", e.message);
        }
        offset += data.length;
    }

    public void write_string (string text)
    {
        write ((uint8[]) text.to_utf8 ());
    }

    public uint add_object ()
    {
        object_offsets.resize (object_offsets.length + 1);
        var index = object_offsets.length - 1;
        object_offsets[index] = 0;
        return index + 1;
    }

    public void start_object (uint index)
    {
        object_offsets[index - 1] = (uint)offset;
    }
}

public class PsWriter
{
    public Cairo.PsSurface surface;
    public FileOutputStream stream;

    public PsWriter (FileOutputStream stream)
    {
        this.stream = stream;
        surface = new Cairo.PsSurface.for_stream (write_cairo_data, 0, 0);
    }

    private Cairo.Status write_cairo_data (uint8[] data)
    {
        try
        {
            stream.write_all (data, null, null);
        }
        catch (Error e)
        {
            warning ("Error writing data: %s", e.message);
            return Cairo.Status.WRITE_ERROR;
        }

        return Cairo.Status.SUCCESS;
    }
}