metaforce/specter/lib/FontCache.cpp

#ifndef NOMINMAX
#define NOMINMAX 1
#endif

#include "specter/FontCache.hpp"

#include <cstddef>
#include <cstdint>
#include <memory>
#include <vector>

#include <athena/FileReader.hpp>
#include <athena/FileWriter.hpp>
#include <athena/MemoryReader.hpp>

#include <boo/System.hpp>

#include FT_GZIP_H
#include FT_SYSTEM_H
#include FT_OUTLINE_H
#include <freetype/internal/internal.h>
#include <freetype/internal/ftstream.h>
#include <freetype/internal/tttypes.h>

#include <hecl/hecl.hpp>
#include <hecl/Runtime.hpp>

#include <logvisor/logvisor.hpp>
#include <xxhash/xxhash.h>
#include <zlib.h>

extern "C" const uint8_t DROIDSANS_PERMISSIVE[];
extern "C" size_t DROIDSANS_PERMISSIVE_SZ;

extern "C" const uint8_t BMONOFONT[];
extern "C" size_t BMONOFONT_SZ;

extern "C" const uint8_t SPECTERCURVES[];
extern "C" size_t SPECTERCURVES_SZ;

extern "C" const FT_Driver_ClassRec tt_driver_class;

namespace specter {
static logvisor::Module Log("specter::FontCache");

const FCharFilter AllCharFilter{"all-glyphs", [](uint32_t) { return true; }};

const FCharFilter LatinCharFilter{"latin-glyphs",
                                  [](uint32_t c) { return c <= 0xff || (c - 0x2200) <= (0x23FF - 0x2200); }};

const FCharFilter LatinAndJapaneseCharFilter{"latin-and-jp-glyphs", [](uint32_t c) {
                                               return LatinCharFilter.second(c) || (c - 0x2E00) <= (0x30FF - 0x2E00) ||
                                                      (c - 0x4E00) <= (0x9FFF - 0x4E00) ||
                                                      (c - 0xFF00) <= (0xFFEF - 0xFF00);
                                             }};

FontTag::FontTag(std::string_view name, bool subpixel, float points, uint32_t dpi) {
  XXH64_state_t st;
  XXH64_reset(&st, 0);
  XXH64_update(&st, name.data(), name.size());
  XXH64_update(&st, &subpixel, 1);
  XXH64_update(&st, &points, 4);
  XXH64_update(&st, &dpi, 4);
  m_hash = XXH64_digest(&st);
}

FreeTypeGZipMemFace::FreeTypeGZipMemFace(FT_Library lib, const uint8_t* data, size_t sz) : m_lib(lib) {
  m_comp.base = (unsigned char*)data;
  m_comp.size = sz;
  m_comp.memory = lib->memory;
}

void FreeTypeGZipMemFace::open() {
  if (m_face)
    return;

  if (FT_Stream_OpenGzip(&m_decomp, &m_comp))
    Log.report(logvisor::Fatal, fmt("unable to open FreeType gzip stream"));

  FT_Open_Args args = {FT_OPEN_STREAM, nullptr, 0, nullptr, &m_decomp};

  if (FT_Open_Face(m_lib, &args, 0, &m_face))
    Log.report(logvisor::Fatal, fmt("unable to open FreeType gzip face"));
}

void FreeTypeGZipMemFace::close() {
  if (!m_face)
    return;
  FT_Done_Face(m_face);
  m_face = nullptr;
}

#define TEXMAP_DIM 1024

static unsigned RoundUpPow2(unsigned v) {
  v--;
  v |= v >> 1;
  v |= v >> 2;
  v |= v >> 4;
  v |= v >> 8;
  v |= v >> 16;
  v++;
  return v;
}

using GreyPixel = uint8_t;
static void MemcpyRect(GreyPixel* img, const FT_Bitmap* bmp, unsigned slice, unsigned x, unsigned y) {
  unsigned sy = TEXMAP_DIM * slice + y;
  for (unsigned i = 0; i < bmp->rows; ++i) {
    const unsigned char* s = &bmp->buffer[bmp->pitch * i];
    GreyPixel* t = &img[TEXMAP_DIM * (sy + i) + x];
    memcpy(t, s, bmp->width);
  }
}

union RgbaPixel {
  uint8_t rgba[4];
  uint32_t pixel;
};
static void MemcpyRect(RgbaPixel* img, const FT_Bitmap* bmp, unsigned slice, unsigned x, unsigned y) {
  unsigned sy = TEXMAP_DIM * slice + y;
  for (unsigned i = 0; i < bmp->rows; ++i) {
    const unsigned char* s = &bmp->buffer[bmp->pitch * i];
    RgbaPixel* t = &img[TEXMAP_DIM * (sy + i) + x];
    for (unsigned j = 0; j < bmp->width / 3; ++j) {
      t[j].rgba[0] = s[j * 3];
      t[j].rgba[1] = s[j * 3 + 1];
      t[j].rgba[2] = s[j * 3 + 2];
      t[j].rgba[3] = 0xff;
    }
  }
}

static void GridFitGlyph(FT_GlyphSlot slot, FT_UInt& width, FT_UInt& height) {
  width = slot->metrics.width >> 6;
  height = slot->metrics.height >> 6;
}

void FontAtlas::buildKernTable(FT_Face face) {
  if (face->driver->clazz == &tt_driver_class) {
    TT_Face ttface = reinterpret_cast<TT_Face>(face);
    if (!ttface->kern_table)
      return;
    athena::io::MemoryReader r(ttface->kern_table, ttface->kern_table_size);
    auto it = m_kernAdjs.end();
    atUint32 nSubs = r.readUint32Big();
    for (atUint32 i = 0; i < nSubs; ++i) {
      TT_KernHead kernHead;
      kernHead.read(r);
      if (kernHead.coverage >> 8 != 0) {
        r.seek(kernHead.length - 6, athena::SeekOrigin::Current);
        continue;
      }

      TT_KernSubHead subHead;
      subHead.read(r);

      for (atUint16 p = 0; p < subHead.nPairs; ++p) {
        TT_KernPair pair;
        pair.read(r);
        if (it == m_kernAdjs.end() || it->first != pair.left)
          if ((it = m_kernAdjs.find(pair.left)) == m_kernAdjs.end())
            it = m_kernAdjs.insert(std::make_pair(pair.left, std::vector<std::pair<atUint16, atInt16>>())).first;
        it->second.emplace_back(pair.right, pair.value);
      }
    }
  }
}

#define NO_ZLIB 0
#define ZLIB_BUF_SZ 32768

static void WriteCompressed(athena::io::FileWriter& writer, const atUint8* data, size_t sz) {
#if NO_ZLIB
  writer.writeUBytes(data, sz);
  return;
#endif

  atUint8 compBuf[ZLIB_BUF_SZ];
  z_stream z = {};
  deflateInit(&z, Z_DEFAULT_COMPRESSION);
  z.next_in = (Bytef*)data;
  z.avail_in = sz;
  writer.writeUint32Big(sz);
  atUint64 adlerPos = writer.position();
  writer.writeUint32Big(0); /* Space for adler32 */
  while (z.avail_in) {
    z.next_out = compBuf;
    z.avail_out = ZLIB_BUF_SZ;
    deflate(&z, Z_NO_FLUSH);
    writer.writeUBytes(compBuf, ZLIB_BUF_SZ - z.avail_out);
  }

  int finishCycle = Z_OK;
  while (finishCycle != Z_STREAM_END) {
    z.next_out = compBuf;
    z.avail_out = ZLIB_BUF_SZ;
    finishCycle = deflate(&z, Z_FINISH);
    writer.writeUBytes(compBuf, ZLIB_BUF_SZ - z.avail_out);
  }

  writer.seek(adlerPos, athena::SeekOrigin::Begin);
  writer.writeUint32Big(z.adler);

  deflateEnd(&z);
}

static bool ReadDecompressed(athena::io::FileReader& reader, atUint8* data, size_t sz) {
#if NO_ZLIB
  reader.readUBytesToBuf(data, sz);
  return true;
#endif

  atUint8 compBuf[ZLIB_BUF_SZ];
  z_stream z = {};
  inflateInit(&z);
  z.next_out = data;
  atUint32 targetSz = reader.readUint32Big();
  atUint32 adler32 = reader.readUint32Big();
  z.avail_out = std::min(sz, size_t(targetSz));
  size_t readSz;
  while ((readSz = reader.readUBytesToBuf(compBuf, ZLIB_BUF_SZ))) {
    z.next_in = compBuf;
    z.avail_in = readSz;
    if (inflate(&z, Z_NO_FLUSH) == Z_STREAM_END)
      break;
  }

  inflateEnd(&z);
  return adler32 == z.adler;
}

FontAtlas::FontAtlas(FT_Face face, uint32_t dpi, bool subpixel, FCharFilter& filter, athena::io::FileWriter& writer)
: m_dpi(dpi)
, m_ftXscale(face->size->metrics.x_scale)
, m_ftXPpem(face->size->metrics.x_ppem)
, m_lineHeight(face->size->metrics.height)
, m_subpixel(subpixel) {
  FT_Int32 baseFlags = FT_LOAD_NO_BITMAP;
  if (subpixel)
    baseFlags |= FT_LOAD_TARGET_LCD;
  else
    baseFlags |= FT_LOAD_TARGET_NORMAL;

  /* First count glyphs exposed by unicode charmap and tally required area */
  size_t glyphCount = 0;
  FT_UInt gindex;
  FT_ULong charcode = FT_Get_First_Char(face, &gindex);
  unsigned curLineWidth = 1;
  unsigned curLineHeight = 0;
  unsigned totalHeight = 1;
  m_fullTexmapLayers = 0;
  while (gindex != 0) {
    if (!filter.second(charcode)) {
      charcode = FT_Get_Next_Char(face, charcode, &gindex);
      continue;
    }
    ++glyphCount;
    FT_Load_Glyph(face, gindex, baseFlags);
    FT_UInt width, height;
    GridFitGlyph(face->glyph, width, height);
    if (curLineWidth + width + 1 > TEXMAP_DIM) {
      totalHeight += curLineHeight + 1;
      curLineHeight = 0;
      curLineWidth = 1;
    }
    curLineHeight = std::max(curLineHeight, height);
    if (totalHeight + curLineHeight + 1 > TEXMAP_DIM) {
      totalHeight = 1;
      ++m_fullTexmapLayers;
      // printf("StagedB: %u\n", gindex);
      curLineHeight = 0;
      curLineWidth = 1;
    }
    curLineWidth += width + 1;
    charcode = FT_Get_Next_Char(face, charcode, &gindex);
  }
  if (curLineHeight)
    totalHeight += curLineHeight + 1;
  m_glyphs.reserve(glyphCount);
  m_glyphLookup.reserve(glyphCount);

  totalHeight = RoundUpPow2(totalHeight);
  m_finalHeight = m_fullTexmapLayers ? TEXMAP_DIM : totalHeight;
  writer.writeUint32Big(m_fullTexmapLayers + 1);
  writer.writeUint32Big(TEXMAP_DIM);
  writer.writeUint32Big(m_finalHeight);

  if (subpixel) {
    /* Allocate texmap */
    if (m_fullTexmapLayers) {
      // printf("ALLOC: %u\n", fullTexmapLayers + 1);
      size_t count = TEXMAP_DIM * TEXMAP_DIM * (m_fullTexmapLayers + 1);
      m_texmap.resize(count * sizeof(RgbaPixel));
    } else {
      size_t count = TEXMAP_DIM * totalHeight;
      m_texmap.resize(count * sizeof(RgbaPixel));
    }

    /* Assemble glyph texmaps and internal data structures */
    charcode = FT_Get_First_Char(face, &gindex);
    curLineWidth = 1;
    curLineHeight = 0;
    totalHeight = 1;
    m_fullTexmapLayers = 0;
    while (gindex != 0) {
      if (!filter.second(charcode)) {
        charcode = FT_Get_Next_Char(face, charcode, &gindex);
        continue;
      }

      FT_Load_Glyph(face, gindex, FT_LOAD_RENDER | baseFlags);
      FT_UInt width, height;
      GridFitGlyph(face->glyph, width, height);
      if (curLineWidth + width + 1 > TEXMAP_DIM) {
        totalHeight += curLineHeight + 1;
        curLineHeight = 0;
        curLineWidth = 1;
      }
      curLineHeight = std::max(curLineHeight, height);
      if (totalHeight + curLineHeight + 1 > TEXMAP_DIM) {
        totalHeight = 1;
        ++m_fullTexmapLayers;
        // printf("RealB: %u\n", gindex);
        curLineHeight = 0;
        curLineWidth = 1;
      }

      m_glyphLookup.insert_or_assign(charcode, m_glyphs.size());
      Glyph& g = m_glyphs.emplace_back();
      g.m_unicodePoint = charcode;
      g.m_glyphIdx = gindex;
      g.m_layerIdx = m_fullTexmapLayers;
      g.m_layerFloat = float(g.m_layerIdx);
      g.m_width = face->glyph->bitmap.width / 3;
      g.m_height = face->glyph->bitmap.rows;
      g.m_uv[0] = curLineWidth / float(TEXMAP_DIM);
      g.m_uv[1] = totalHeight / float(m_finalHeight);
      g.m_uv[2] = g.m_uv[0] + g.m_width / float(TEXMAP_DIM);
      g.m_uv[3] = g.m_uv[1] + g.m_height / float(m_finalHeight);
      g.m_leftPadding = face->glyph->metrics.horiBearingX >> 6;
      g.m_advance = face->glyph->advance.x >> 6;
      g.m_verticalOffset = (face->glyph->metrics.horiBearingY - face->glyph->metrics.height) >> 6;
      MemcpyRect((RgbaPixel*)m_texmap.data(), &face->glyph->bitmap, m_fullTexmapLayers, curLineWidth, totalHeight);
      curLineWidth += width + 1;
      charcode = FT_Get_Next_Char(face, charcode, &gindex);
    }

    WriteCompressed(writer, m_texmap.data(), m_texmap.size());
  } else {
    /* Allocate texmap */
    if (m_fullTexmapLayers) {
      // printf("ALLOC: %u\n", fullTexmapLayers + 1);
      size_t count = TEXMAP_DIM * TEXMAP_DIM * (m_fullTexmapLayers + 1);
      m_texmap.resize(count * sizeof(GreyPixel));
    } else {
      size_t count = TEXMAP_DIM * totalHeight;
      m_texmap.resize(count * sizeof(GreyPixel));
    }

    /* Assemble glyph texmaps and internal data structures */
    charcode = FT_Get_First_Char(face, &gindex);
    curLineWidth = 1;
    curLineHeight = 0;
    totalHeight = 1;
    m_fullTexmapLayers = 0;
    while (gindex != 0) {
      if (!filter.second(charcode)) {
        charcode = FT_Get_Next_Char(face, charcode, &gindex);
        continue;
      }

      FT_Load_Glyph(face, gindex, FT_LOAD_RENDER | baseFlags);
      FT_UInt width, height;
      GridFitGlyph(face->glyph, width, height);
      if (curLineWidth + width + 1 > TEXMAP_DIM) {
        totalHeight += curLineHeight + 1;
        curLineHeight = 0;
        curLineWidth = 1;
      }
      curLineHeight = std::max(curLineHeight, height);
      if (totalHeight + curLineHeight + 1 > TEXMAP_DIM) {
        totalHeight = 1;
        ++m_fullTexmapLayers;
        // printf("RealB: %u\n", gindex);
        curLineHeight = 0;
        curLineWidth = 1;
      }

      m_glyphLookup.insert_or_assign(charcode, m_glyphs.size());
      Glyph& g = m_glyphs.emplace_back();
      g.m_unicodePoint = charcode;
      g.m_glyphIdx = gindex;
      g.m_layerIdx = m_fullTexmapLayers;
      g.m_layerFloat = float(g.m_layerIdx);
      g.m_width = face->glyph->bitmap.width;
      g.m_height = face->glyph->bitmap.rows;
      g.m_uv[0] = curLineWidth / float(TEXMAP_DIM);
      g.m_uv[1] = totalHeight / float(m_finalHeight);
      g.m_uv[2] = g.m_uv[0] + g.m_width / float(TEXMAP_DIM);
      g.m_uv[3] = g.m_uv[1] + g.m_height / float(m_finalHeight);
      g.m_leftPadding = face->glyph->metrics.horiBearingX >> 6;
      g.m_advance = face->glyph->advance.x >> 6;
      g.m_verticalOffset = (face->glyph->metrics.horiBearingY - face->glyph->metrics.height) >> 6;
      MemcpyRect(m_texmap.data(), &face->glyph->bitmap, m_fullTexmapLayers, curLineWidth, totalHeight);
      curLineWidth += width + 1;
      charcode = FT_Get_Next_Char(face, charcode, &gindex);
    }

    WriteCompressed(writer, m_texmap.data(), m_texmap.size());
  }

  buildKernTable(face);
  m_ready = true;
}

FontAtlas::FontAtlas(FT_Face face, uint32_t dpi, bool subpixel, FCharFilter& filter, athena::io::FileReader& reader)
: m_dpi(dpi)
, m_ftXscale(face->size->metrics.x_scale)
, m_ftXPpem(face->size->metrics.x_ppem)
, m_lineHeight(face->size->metrics.height)
, m_subpixel(subpixel) {
  FT_Int32 baseFlags = FT_LOAD_NO_BITMAP;
  if (subpixel)
    baseFlags |= FT_LOAD_TARGET_LCD;
  else
    baseFlags |= FT_LOAD_TARGET_NORMAL;

  /* First count glyphs exposed by unicode charmap */
  size_t glyphCount = 0;
  FT_UInt gindex;
  FT_ULong charcode = FT_Get_First_Char(face, &gindex);
  while (gindex != 0) {
    if (!filter.second(charcode)) {
      charcode = FT_Get_Next_Char(face, charcode, &gindex);
      continue;
    }
    ++glyphCount;
    charcode = FT_Get_Next_Char(face, charcode, &gindex);
  }
  m_glyphs.reserve(glyphCount);
  m_glyphLookup.reserve(glyphCount);

  m_fullTexmapLayers = reader.readUint32Big() - 1;
  reader.readUint32Big();
  m_finalHeight = reader.readUint32Big();

  if (subpixel) {
    /* Allocate texmap */
    if (m_fullTexmapLayers) {
      // printf("ALLOC: %u\n", fullTexmapLayers + 1);
      size_t count = TEXMAP_DIM * TEXMAP_DIM * (m_fullTexmapLayers + 1);
      m_texmap.resize(count * sizeof(RgbaPixel));
    } else {
      size_t count = TEXMAP_DIM * m_finalHeight;
      m_texmap.resize(count * sizeof(RgbaPixel));
    }

    /* Assemble glyph texmaps and internal data structures */
    charcode = FT_Get_First_Char(face, &gindex);
    unsigned curLineWidth = 1;
    unsigned curLineHeight = 0;
    unsigned totalHeight = 1;
    m_fullTexmapLayers = 0;
    while (gindex != 0) {
      if (!filter.second(charcode)) {
        charcode = FT_Get_Next_Char(face, charcode, &gindex);
        continue;
      }

      FT_Load_Glyph(face, gindex, baseFlags);
      FT_UInt width, height;
      GridFitGlyph(face->glyph, width, height);
      if (curLineWidth + width + 1 > TEXMAP_DIM) {
        totalHeight += curLineHeight + 1;
        curLineHeight = 0;
        curLineWidth = 1;
      }
      curLineHeight = std::max(curLineHeight, height);
      if (totalHeight + curLineHeight + 1 > TEXMAP_DIM) {
        totalHeight = 1;
        ++m_fullTexmapLayers;
        // printf("RealB: %u\n", gindex);
        curLineHeight = 0;
        curLineWidth = 1;
      }

      m_glyphLookup.insert_or_assign(charcode, m_glyphs.size());
      Glyph& g = m_glyphs.emplace_back();
      g.m_unicodePoint = charcode;
      g.m_glyphIdx = gindex;
      g.m_layerIdx = m_fullTexmapLayers;
      g.m_layerFloat = float(g.m_layerIdx);
      g.m_width = width;
      g.m_height = height;
      g.m_uv[0] = curLineWidth / float(TEXMAP_DIM);
      g.m_uv[1] = totalHeight / float(m_finalHeight);
      g.m_uv[2] = g.m_uv[0] + g.m_width / float(TEXMAP_DIM);
      g.m_uv[3] = g.m_uv[1] + g.m_height / float(m_finalHeight);
      g.m_leftPadding = face->glyph->metrics.horiBearingX >> 6;
      g.m_advance = face->glyph->advance.x >> 6;
      g.m_verticalOffset = (face->glyph->metrics.horiBearingY - face->glyph->metrics.height) >> 6;
      curLineWidth += width + 1;
      charcode = FT_Get_Next_Char(face, charcode, &gindex);
    }

    if (!ReadDecompressed(reader, m_texmap.data(), m_texmap.size()))
      return;
  } else {
    /* Allocate texmap */
    if (m_fullTexmapLayers) {
      // printf("ALLOC: %u\n", fullTexmapLayers + 1);
      size_t count = TEXMAP_DIM * TEXMAP_DIM * (m_fullTexmapLayers + 1);
      m_texmap.resize(count * sizeof(GreyPixel));
    } else {
      size_t count = TEXMAP_DIM * m_finalHeight;
      m_texmap.resize(count * sizeof(GreyPixel));
    }

    /* Assemble glyph texmaps and internal data structures */
    charcode = FT_Get_First_Char(face, &gindex);
    unsigned curLineWidth = 1;
    unsigned curLineHeight = 0;
    unsigned totalHeight = 1;
    m_fullTexmapLayers = 0;
    while (gindex != 0) {
      if (!filter.second(charcode)) {
        charcode = FT_Get_Next_Char(face, charcode, &gindex);
        continue;
      }

      FT_Load_Glyph(face, gindex, baseFlags);
      FT_UInt width, height;
      GridFitGlyph(face->glyph, width, height);
      if (curLineWidth + width + 1 > TEXMAP_DIM) {
        totalHeight += curLineHeight + 1;
        curLineHeight = 0;
        curLineWidth = 1;
      }
      curLineHeight = std::max(curLineHeight, height);
      if (totalHeight + curLineHeight + 1 > TEXMAP_DIM) {
        totalHeight = 1;
        ++m_fullTexmapLayers;
        // printf("RealB: %u\n", gindex);
        curLineHeight = 0;
        curLineWidth = 1;
      }

      m_glyphLookup.insert_or_assign(charcode, m_glyphs.size());
      Glyph& g = m_glyphs.emplace_back();
      g.m_unicodePoint = charcode;
      g.m_glyphIdx = gindex;
      g.m_layerIdx = m_fullTexmapLayers;
      g.m_layerFloat = float(g.m_layerIdx);
      g.m_width = width;
      g.m_height = height;
      g.m_uv[0] = curLineWidth / float(TEXMAP_DIM);
      g.m_uv[1] = totalHeight / float(m_finalHeight);
      g.m_uv[2] = g.m_uv[0] + g.m_width / float(TEXMAP_DIM);
      g.m_uv[3] = g.m_uv[1] + g.m_height / float(m_finalHeight);
      g.m_leftPadding = face->glyph->metrics.horiBearingX >> 6;
      g.m_advance = face->glyph->advance.x >> 6;
      g.m_verticalOffset = (face->glyph->metrics.horiBearingY - face->glyph->metrics.height) >> 6;
      curLineWidth += width + 1;
      charcode = FT_Get_Next_Char(face, charcode, &gindex);
    }

    if (!ReadDecompressed(reader, m_texmap.data(), m_texmap.size()))
      return;
  }

  buildKernTable(face);
  m_ready = true;
}

boo::ObjToken<boo::ITextureSA> FontAtlas::texture(boo::IGraphicsDataFactory* gf) const {
  if (!m_ready)
    return {};
  if (m_tex)
    return m_tex;
  gf->commitTransaction([&](boo::IGraphicsDataFactory::Context& ctx) {
    if (m_subpixel)
      const_cast<boo::ObjToken<boo::ITextureSA>&>(m_tex) =
          ctx.newStaticArrayTexture(TEXMAP_DIM, m_finalHeight, m_fullTexmapLayers + 1, 1, boo::TextureFormat::RGBA8,
                                    boo::TextureClampMode::Repeat, m_texmap.data(), m_texmap.size());
    else
      const_cast<boo::ObjToken<boo::ITextureSA>&>(m_tex) =
          ctx.newStaticArrayTexture(TEXMAP_DIM, m_finalHeight, m_fullTexmapLayers + 1, 1, boo::TextureFormat::I8,
                                    boo::TextureClampMode::Repeat, m_texmap.data(), m_texmap.size());
    const_cast<std::vector<uint8_t>&>(m_texmap) = std::vector<uint8_t>();
    return true;
  } BooTrace);
  return m_tex;
}

FontCache::Library::Library() {
  FT_Error err = FT_Init_FreeType(&m_lib);
  if (err)
    Log.report(logvisor::Fatal, fmt("unable to FT_Init_FreeType"));
}

FontCache::Library::~Library() { FT_Done_FreeType(m_lib); }

FontCache::FontCache(const hecl::Runtime::FileStoreManager& fileMgr)
: m_fileMgr(fileMgr)
, m_cacheRoot(hecl::SystemString(m_fileMgr.getStoreRoot()) + _SYS_STR("/fontcache"))
, m_regFace(m_fontLib, DROIDSANS_PERMISSIVE, DROIDSANS_PERMISSIVE_SZ)
, m_monoFace(m_fontLib, BMONOFONT, BMONOFONT_SZ)
, m_curvesFace(m_fontLib, SPECTERCURVES, SPECTERCURVES_SZ) {
  hecl::MakeDir(m_cacheRoot.c_str());
}

FontCache::~FontCache() = default;

FontTag FontCache::prepCustomFont(std::string_view name, FT_Face face, FCharFilter filter, bool subpixel, float points,
                                  uint32_t dpi) {
  /* Quick validation */
  if (!face)
    Log.report(logvisor::Fatal, fmt("invalid freetype face"));

  if (!face->charmap || face->charmap->encoding != FT_ENCODING_UNICODE)
    Log.report(logvisor::Fatal, fmt("font does not contain a unicode char map"));

  /* Set size with FreeType */
  FT_Set_Char_Size(face, 0, points * 64.0, 0, dpi);

  /* Make tag and search for cached version */
  const FontTag tag(std::string(name).append(1, '_').append(filter.first), subpixel, points, dpi);
  const auto search = m_cachedAtlases.find(tag);
  if (search != m_cachedAtlases.end()) {
    return tag;
  }

  /* Now check filesystem cache */
  hecl::SystemString cachePath = m_cacheRoot + _SYS_STR('/') + fmt::format(fmt(_SYS_STR("{:x}")), tag.hash());
  hecl::Sstat st;
  if (!hecl::Stat(cachePath.c_str(), &st) && S_ISREG(st.st_mode)) {
    athena::io::FileReader r(cachePath);
    if (!r.hasError()) {
      atUint32 magic = r.readUint32Big();
      if (r.position() == 4 && magic == 'FONT') {
        std::unique_ptr<FontAtlas> fa = std::make_unique<FontAtlas>(face, dpi, subpixel, filter, r);
        if (fa->isReady()) {
          m_cachedAtlases.emplace(tag, std::move(fa));
          return tag;
        }
      }
    }
  }

  /* Nada, build and cache now */
  athena::io::FileWriter w(cachePath);
  if (w.hasError())
    Log.report(logvisor::Fatal, fmt(_SYS_STR("unable to open '{}' for writing")), cachePath);
  w.writeUint32Big('FONT');
  m_cachedAtlases.emplace(tag, std::make_unique<FontAtlas>(face, dpi, subpixel, filter, w));
  return tag;
}

const FontAtlas& FontCache::lookupAtlas(FontTag tag) const {
  auto search = m_cachedAtlases.find(tag);
  if (search == m_cachedAtlases.cend())
    Log.report(logvisor::Fatal, fmt("invalid font"));
  return *search->second.get();
}

} // namespace specter