/*
 * The Font Converter's WOFF2 codec: Google's woff2 library (with brotli)
 * behind four plain C functions. The page copies a font in, asks for the
 * output size, and copies the result out. WOFF 1.0, the outline conversion
 * and everything else are done in TypeScript.
 */
#include <stdint.h>
#include <stdlib.h>
#include <string>
#include <emscripten/emscripten.h>

#include <woff2/decode.h>
#include <woff2/encode.h>
#include <woff2/output.h>

extern "C" {

EMSCRIPTEN_KEEPALIVE void *w2_alloc(size_t n) { return malloc(n ? n : 1); }
EMSCRIPTEN_KEEPALIVE void w2_free(void *p) { free(p); }

/*
 * Decodes WOFF2 into a buffer that grows as needed: the size a file declares
 * is not always the size it rebuilds to (Font Awesome's, with untransformed
 * glyf, come out larger), so a fixed buffer of that size can fail.
 * Returns the decoded length, or 0 on error; w2_decoded() points at it until
 * the next call.
 */
static std::string decoded;
EMSCRIPTEN_KEEPALIVE size_t w2_decode(const uint8_t *data, size_t len) {
  decoded.clear();
  woff2::WOFF2StringOut out(&decoded);
  out.SetMaxSize(256 * 1024 * 1024);
  if (!woff2::ConvertWOFF2ToTTF(data, len, &out)) {
    decoded.clear();
    return 0;
  }
  return out.Size();
}
EMSCRIPTEN_KEEPALIVE const uint8_t *w2_decoded(void) {
  return reinterpret_cast<const uint8_t *>(decoded.data());
}

/* The most a font can grow to as WOFF2, to size the output buffer. */
EMSCRIPTEN_KEEPALIVE size_t w2_max_encoded_size(const uint8_t *data, size_t len) {
  return woff2::MaxWOFF2CompressedSize(data, len);
}

/* Encodes a TrueType/OpenType font as WOFF2. *out_len is the buffer size in, the result size out. Returns 1 on success. */
EMSCRIPTEN_KEEPALIVE int w2_encode(const uint8_t *data, size_t len, uint8_t *out, size_t *out_len) {
  return woff2::ConvertTTFToWOFF2(data, len, out, out_len) ? 1 : 0;
}

}