#include <stdint.h>
#include <stdlib.h>

#include <harfbuzz-external.h>
#include <harfbuzz-impl.h>
#include <harfbuzz-shaper.h>
#include "harfbuzz-unicode.h"

#include "tables/grapheme-break-properties.h"
#include "tables/mirroring-properties.h"
#include "tables/script-properties.h"

uint32_t
utf16_to_code_point(const uint16_t *chars, size_t len, ssize_t *iter) {
  const uint16_t v = chars[(*iter)++];
  if (HB_IsHighSurrogate(v)) {
    // surrogate pair
    if (*iter >= len) {
      // the surrogate is incomplete.
      return HB_InvalidCodePoint;
    }
    const uint16_t v2 = chars[(*iter)++];
    if (!HB_IsLowSurrogate(v2)) {
      // invalidate surrogate pair.
      return HB_InvalidCodePoint;
    }

    return HB_SurrogateToUcs4(v, v2);
  }

  if (HB_IsLowSurrogate(v)) {
    // this isn't a valid code point
    return HB_InvalidCodePoint;
  }

  return v;
}

uint32_t
utf16_to_code_point_prev(const uint16_t *chars, size_t len, ssize_t *iter) {
  const uint16_t v = chars[(*iter)--];
  if (HB_IsLowSurrogate(v)) {
    // surrogate pair
    if (*iter < 0) {
      // the surrogate is incomplete.
      return HB_InvalidCodePoint;
    }
    const uint16_t v2 = chars[(*iter)--];
    if (!HB_IsHighSurrogate(v2)) {
      // invalidate surrogate pair.
      return HB_InvalidCodePoint;
    }

    return HB_SurrogateToUcs4(v2, v);
  }

  if (HB_IsHighSurrogate(v)) {
    // this isn't a valid code point
    return HB_InvalidCodePoint;
  }

  return v;
}

static int
script_property_cmp(const void *vkey, const void *vcandidate) {
  const uint32_t key = (uint32_t) (intptr_t) vkey;
  const struct script_property *candidate = vcandidate;

  if (key < candidate->range_start) {
    return -1;
  } else if (key > candidate->range_end) {
    return 1;
  } else {
    return 0;
  }
}

HB_Script
code_point_to_script(uint32_t cp) {
  if (cp == 0) {
    // bsearch can throw an assertion on null pointer, so skip if zero
    return HB_Script_Common;
  }
  const void *vprop = bsearch((void *) (intptr_t) cp, script_properties,
                              script_properties_count,
                              sizeof(struct script_property),
                              script_property_cmp);
  if (!vprop)
    return HB_Script_Common;

  return ((const struct script_property *) vprop)->script;
}

char
hb_utf16_script_run_next(unsigned *num_code_points, HB_ScriptItem *output,
                         const uint16_t *chars, size_t len, ssize_t *iter) {
  if (*iter == len)
    return 0;

  output->pos = *iter;
  const uint32_t init_cp = utf16_to_code_point(chars, len, iter);
  unsigned cps = 1;
  if (init_cp == HB_InvalidCodePoint)
    return 0;
  const HB_Script init_script = code_point_to_script(init_cp);
  HB_Script current_script = init_script;
  output->script = init_script;

  for (;;) {
    if (*iter == len)
      break;
    const ssize_t prev_iter = *iter;
    const uint32_t cp = utf16_to_code_point(chars, len, iter);
    if (cp == HB_InvalidCodePoint)
      return 0;
    cps++;
    const HB_Script script = code_point_to_script(cp);

    if (script != current_script) {
        /* BEGIN android-changed
           The condition was not correct by doing "a == b == constant"
           END android-changed */
      if (current_script == HB_Script_Inherited && init_script == HB_Script_Inherited) {
        // If we started off as inherited, we take whatever we can find.
        output->script = script;
        current_script = script;
        continue;
      } else if (script == HB_Script_Inherited) {
        continue;
      } else {
        *iter = prev_iter;
        cps--;
        break;
      }
    }
  }

  if (output->script == HB_Script_Inherited)
    output->script = HB_Script_Common;

  output->length = *iter - output->pos;
  if (num_code_points)
    *num_code_points = cps;
  return 1;
}

char
hb_utf16_script_run_prev(unsigned *num_code_points, HB_ScriptItem *output,
                         const uint16_t *chars, size_t len, ssize_t *iter) {
  if (*iter == (size_t) -1)
    return 0;

  const size_t ending_index = *iter;
  const uint32_t init_cp = utf16_to_code_point_prev(chars, len, iter);
  unsigned cps = 1;
  if (init_cp == HB_InvalidCodePoint)
    return 0;
  const HB_Script init_script = code_point_to_script(init_cp);
  HB_Script current_script = init_script;
  output->script = init_script;

  for (;;) {
    if (*iter < 0)
      break;
    const ssize_t prev_iter = *iter;
    const uint32_t cp = utf16_to_code_point_prev(chars, len, iter);
    if (cp == HB_InvalidCodePoint)
      return 0;
    cps++;
    const HB_Script script = code_point_to_script(cp);

    if (script != current_script) {
      if (current_script == HB_Script_Inherited && init_script == HB_Script_Inherited) {
        // If we started off as inherited, we take whatever we can find.
        output->script = script;
        current_script = script;
        continue;
      } else if (script == HB_Script_Inherited) {
        /* BEGIN android-changed
           We apply the same fix for Chrome to Android.
           Chrome team will talk with upsteam about it.
           Just assume that whatever follows this combining character is within
           the same script.  This is incorrect if you had language1 + combining
           char + language 2, but that is rare and this code is suspicious
           anyway.
           END android-changed */
        continue;
      } else {
        *iter = prev_iter;
        cps--;
        break;
      }
    }
  }

  if (output->script == HB_Script_Inherited)
    output->script = HB_Script_Common;

  output->pos = *iter + 1;
  output->length = ending_index - *iter;
  if (num_code_points)
    *num_code_points = cps;
  return 1;
}

static int
grapheme_break_property_cmp(const void *vkey, const void *vcandidate) {
  const uint32_t key = (uint32_t) (intptr_t) vkey;
  const struct grapheme_break_property *candidate = vcandidate;

  if (key < candidate->range_start) {
    return -1;
  } else if (key > candidate->range_end) {
    return 1;
  } else {
    return 0;
  }
}

HB_GraphemeClass
HB_GetGraphemeClass(HB_UChar32 ch) {
  const void *vprop = bsearch((void *) (intptr_t) ch, grapheme_break_properties,
                              grapheme_break_properties_count,
                              sizeof(struct grapheme_break_property),
                              grapheme_break_property_cmp);
  if (!vprop)
    return HB_Grapheme_Other;

  return ((const struct grapheme_break_property *) vprop)->klass;
}

HB_WordClass
HB_GetWordClass(HB_UChar32 ch) {
  abort();
  return 0;
}

HB_SentenceClass
HB_GetSentenceClass(HB_UChar32 ch) {
  abort();
  return 0;
}

void
HB_GetGraphemeAndLineBreakClass(HB_UChar32 ch, HB_GraphemeClass *gclass, HB_LineBreakClass *breakclass) {
  *gclass = HB_GetGraphemeClass(ch);
  *breakclass = HB_GetLineBreakClass(ch);
}

static int
mirroring_property_cmp(const void *vkey, const void *vcandidate) {
  const uint32_t key = (uint32_t) (intptr_t) vkey;
  const struct mirroring_property *candidate = vcandidate;

  if (key < candidate->a) {
    return -1;
  } else if (key > candidate->a) {
    return 1;
  } else {
    return 0;
  }
}

HB_UChar16
HB_GetMirroredChar(HB_UChar16 ch) {
  const void *mprop = bsearch((void *) (intptr_t) ch, mirroring_properties,
                              mirroring_properties_count,
                              sizeof(struct mirroring_property),
                              mirroring_property_cmp);
  if (!mprop)
    return ch;

  return ((const struct mirroring_property *) mprop)->b;
}

void *
HB_Library_Resolve(const char *library, int version, const char *symbol) {
  abort();
  return NULL;
}