/*

 * Copyright (c) 2020, Stephan Unverwerth <s.unverwerth@serenityos.org>

 * Copyright (c) 2023, Andreas Kling <kling@serenityos.org>

 *

 * SPDX-License-Identifier: BSD-2-Clause

 */

#pragma once

#include <AK/Bitmap.h>

#include <AK/ByteReader.h>

#include <AK/RefCounted.h>

#include <AK/RefPtr.h>

#include <AK/String.h>

#include <AK/Types.h>

#include <LibCore/MappedFile.h>

#include <LibGfx/Bitmap.h>

#include <LibGfx/Size.h>

namespace Gfx {

// FIXME: Make a MutableGlyphBitmap buddy class for FontEditor instead?

class GlyphBitmap {

public:

    GlyphBitmap() = default;

    GlyphBitmap(Bytes rows, IntSize size)

        : m_rows(rows)

        , m_size(size)

    {

    }

    unsigned row(unsigned index) const { return ByteReader::load32(bitmap(index).data()); }

    bool bit_at(int x, int y) const { return bitmap(y).get(x); }

    void set_bit_at(int x, int y, bool b) { bitmap(y).set(x, b); }

    IntSize size() const { return m_size; }

    int width() const { return m_size.width(); }

    int height() const { return m_size.height(); }

    static constexpr size_t bytes_per_row() { return sizeof(u32); }

    static constexpr int max_width() { return bytes_per_row() * 8; }

    static constexpr int max_height() { return max_width() + bytes_per_row(); }

private:

    AK::Bitmap bitmap(size_t y) const

    {

        return { const_cast<u8*>(m_rows.offset_pointer(bytes_per_row() * y)), bytes_per_row() * 8 };

    }

    Bytes m_rows;

    IntSize m_size { 0, 0 };

};

class Glyph {

public:

    Glyph(GlyphBitmap const& glyph_bitmap, float left_bearing, float advance, float ascent)

        : m_glyph_bitmap(glyph_bitmap)

        , m_left_bearing(left_bearing)

        , m_advance(advance)

        , m_ascent(ascent)

    {

    }

    Glyph(RefPtr<Bitmap> bitmap, float left_bearing, float advance, float ascent, bool is_color_bitmap)

        : m_bitmap(bitmap)

        , m_left_bearing(left_bearing)

        , m_advance(advance)

        , m_ascent(ascent)

        , m_color_bitmap(is_color_bitmap)

    {

    }

    bool is_color_bitmap() const { return m_color_bitmap; }

    bool is_glyph_bitmap() const { return !m_bitmap; }

    GlyphBitmap glyph_bitmap() const { return m_glyph_bitmap; }

    RefPtr<Bitmap> bitmap() const { return m_bitmap; }

    float left_bearing() const { return m_left_bearing; }

    float advance() const { return m_advance; }

    float ascent() const { return m_ascent; }

private:

    GlyphBitmap m_glyph_bitmap;

    RefPtr<Bitmap> m_bitmap;

    float m_left_bearing;

    float m_advance;

    float m_ascent;

    bool m_color_bitmap { false };

};

struct GlyphSubpixelOffset {

    u8 x;

    u8 y;

    // TODO: Allow setting this at runtime via some config?

    static constexpr int subpixel_divisions() { return 3; }

    FloatPoint to_float_point() const { return FloatPoint(x / float(subpixel_divisions()), y / float(subpixel_divisions())); }

    bool operator==(GlyphSubpixelOffset const&) const = default;

};

struct GlyphRasterPosition {

    // Where the glyph bitmap should be drawn/blitted.

    IntPoint blit_position;

    // A subpixel offset to be used when rendering the glyph.

    // This improves kerning and alignment at the expense of caching a few extra bitmaps.

    // This is (currently) snapped to thirds of a subpixel (i.e. 0, 0.33, 0.66).

    GlyphSubpixelOffset subpixel_offset;

    static GlyphRasterPosition get_nearest_fit_for(FloatPoint position);

};

struct FontPixelMetrics {

    float size { 0 };

    float x_height { 0 };

    float advance_of_ascii_zero { 0 };

    float glyph_spacing { 0 };

    // Number of pixels the font extends above the baseline.

    float ascent { 0 };

    // Number of pixels the font descends below the baseline.

    float descent { 0 };

    // Line gap specified by font.

    float line_gap { 0 };

    float line_spacing() const { return ascent + descent + line_gap; }

};

// https://learn.microsoft.com/en-us/typography/opentype/spec/os2#uswidthclass

enum FontWidth {

    UltraCondensed = 1,

    ExtraCondensed = 2,

    Condensed = 3,

    SemiCondensed = 4,

    Normal = 5,

    SemiExpanded = 6,

    Expanded = 7,

    ExtraExpanded = 8,

    UltraExpanded = 9

};

class Font : public RefCounted<Font> {

public:

    enum class AllowInexactSizeMatch {

        No,

        Yes,

        Larger,

        Smaller,

    };

    virtual NonnullRefPtr<Font> clone() const = 0;

    virtual ErrorOr<NonnullRefPtr<Font>> try_clone() const = 0;

    virtual ~Font() = default;

    virtual FontPixelMetrics pixel_metrics() const = 0;

    virtual u8 presentation_size() const = 0;

    virtual u8 slope() const = 0;

    // Font point size (distance between ascender and descender).

    virtual float point_size() const = 0;

    // Font pixel size (distance between ascender and descender).

    virtual float pixel_size() const = 0;

    // Font pixel size, rounded up to the nearest integer.

    virtual int pixel_size_rounded_up() const = 0;

    virtual u16 width() const = 0;

    virtual u16 weight() const = 0;

    virtual Optional<Glyph> glyph(u32 code_point) const = 0;

    virtual Optional<Glyph> glyph(u32 code_point, GlyphSubpixelOffset) const = 0;

    virtual Optional<Glyph> glyph_for_postscript_name(StringView, GlyphSubpixelOffset) const = 0;

    virtual bool contains_glyph(u32 code_point) const = 0;

    virtual bool contains_glyph_for_postscript_name(StringView name) const = 0;

    virtual float glyph_left_bearing(u32 code_point) const = 0;

    virtual Optional<float> glyph_left_bearing_for_postscript_name(StringView) const = 0;

    virtual float glyph_width(u32 code_point) const = 0;

    virtual Optional<float> glyph_width_for_postscript_name(StringView) const = 0;

    virtual float glyph_or_emoji_width(Utf8CodePointIterator&) const = 0;

    virtual float glyph_or_emoji_width(Utf32CodePointIterator&) const = 0;

    virtual float glyphs_horizontal_kerning(u32 left_code_point, u32 right_code_point) const = 0;

    virtual int x_height() const = 0;

    virtual float preferred_line_height() const = 0;

    virtual u8 min_glyph_width() const = 0;

    virtual u8 max_glyph_width() const = 0;

    virtual u8 glyph_fixed_width() const = 0;

    virtual u8 baseline() const = 0;

    virtual u8 mean_line() const = 0;

    virtual float width(StringView) const = 0;

    virtual float width(Utf8View const&) const = 0;

    virtual float width(Utf32View const&) const = 0;

    virtual int width_rounded_up(StringView) const = 0;

    virtual String name() const = 0;

    virtual bool is_fixed_width() const = 0;

    virtual u8 glyph_spacing() const = 0;

    virtual size_t glyph_count() const = 0;

    virtual String family() const = 0;

    virtual String variant() const = 0;

    virtual String qualified_name() const = 0;

    virtual String human_readable_name() const = 0;

    virtual NonnullRefPtr<Font> with_size(float point_size) const = 0;

    Font const& bold_variant() const;

    virtual bool has_color_bitmaps() const = 0;

private:

    mutable RefPtr<Gfx::Font const> m_bold_variant;

};

}