#pragma once

#include "string.h"

using TOKENIZER_COMPARE_FN = FN<U8( char )>;

struct STR_TOKENIZER {
  STR str;
  STR ignored;

  I32 cur;
  I32 last;
};

inline STR_TOKENIZER tok_init( STR str, STR whitespace_chars = " \t\n\r" ) {
  return {
    .str = str,
    .ignored = { whitespace_chars },
    .cur = 0,
    .last = 0,
  };
}

inline STR tok_next( STR_TOKENIZER* t ) {
  if( t->cur >= t->str.size )
    return "";

  U8 start = 0;
  for( I32 i = t->cur; i < t->str.size; i++ ) {
    U8 c = t->str.data[i];
    if( i == t->str.size - 1 ) {
      if( !start )
        return "";

      STR ret = { (U32)i - t->cur + 1, t->str.data + t->cur };
      t->last = t->cur;
      t->cur = i + 1;
      return ret;
    }

    for( auto& it : t->ignored ) {
      if( c == it ) {
        if( !start ) {
          t->cur = i + 1;
          continue;
        } else {
          STR ret = { (U32)i - t->cur, t->str.data + t->cur };
          t->last = t->cur;
          t->cur = i + 1;
          return ret;
        }
      }
    }

    start = 1;
  }

  return "";
}

inline STR tok_peek( STR_TOKENIZER *t ) {
  if( t->cur >= t->str.size )
    return "";

  U8 start = 0;
  I32 cur = t->cur;
  for( I32 i = cur; i < t->str.size; i++ ) {
    U8 c = t->str.data[i];
    if( i == t->str.size - 1 ) {
      if( !start )
        return "";

      STR ret = { (U32)i - cur + 1, t->str.data + cur };
      return ret;
    }

    for( auto& it : t->ignored ) {
      if( c == it ) {
        if( !start ) {
          cur = i + 1;
          continue;
        } else {
          STR ret = { (U32)i - cur, t->str.data + cur };
          return ret;
        }
      }
    }

    start = 1;
  }

  return "";
}


inline STR tok_next( STR_TOKENIZER *t, STR what ) {
  if( t->cur >= t->str.size )
    return "";

  if( !what.size )
    return "";

  for( I32 i = t->cur; i <= t->str.size - what.size; i++ ) {
    STR slice = { what.size, t->str.data + i };
    if( slice == what ) {
      STR ret = { (U32)i - t->cur, t->str.data + i + what.size };
      t->last = t->cur;
      t->cur = i + what.size;
      return ret;
    }
  }

  return "";
}