#include <string.h>
#include "parser_internal.h"

typedef unsigned int *HCharset;

static inline HCharset new_charset(HAllocator* mm__) {
  HCharset cs = h_new(unsigned int, 256 / sizeof(unsigned int));
  memset(cs, 0, 256);
  return cs;
}

static inline int charset_isset(HCharset cs, uint8_t pos) {
  return !!(cs[pos / sizeof(*cs)] & (1 << (pos % sizeof(*cs))));
}

static inline void charset_set(HCharset cs, uint8_t pos, int val) {
  cs[pos / sizeof(*cs)] =
    val
    ? cs[pos / sizeof(*cs)] |  (1 << (pos % sizeof(*cs)))
    : cs[pos / sizeof(*cs)] & ~(1 << (pos % sizeof(*cs)));
}

static HParseResult* parse_charset(void *env, HParseState *state) {
  uint8_t in = h_read_bits(&state->input_stream, 8, false);
  HCharset cs = (HCharset)env;

  if (charset_isset(cs, in)) {
    HParsedToken *tok = a_new(HParsedToken, 1);
    tok->token_type = TT_UINT; tok->uint = in;
    return make_result(state, tok);    
  } else
    return NULL;
}

// FUTURE: this is horribly inefficient
static bool cs_ctrvm(HRVMProg *prog, void *env) {
  HCharset cs = (HCharset)env;
  uint16_t start = h_rvm_get_ip(prog);
  for (size_t i=0; i<256; ++i) {
    if (charset_isset(cs, i)) {
      uint16_t insn = h_rvm_insert_insn(prog, RVM_FORK, 0);
      h_rvm_insert_insn(prog, RVM_MATCH, i & i << 8);
      h_rvm_insert_insn(prog, RVM_GOTO, 0);
      h_rvm_patch_arg(prog, insn, h_rvm_get_ip(prog));
    }
  }
  uint16_t jump = h_rvm_insert_insn(prog, RVM_STEP, 0);
  for (size_t i=start; i<jump; ++i) {
    if (RVM_GOTO == prog->insns[i].op)
      h_rvm_patch_arg(prog, i, jump);
  }
  return true;
}

static const HParserVtable charset_vt = {
  .parse = parse_charset,
  .isValidRegular = h_true,
  .isValidCF = h_true,
  .compile_to_rvm = cs_ctrvm,
};

const HParser* h_ch_range(const uint8_t lower, const uint8_t upper) {
  return h_ch_range__m(&system_allocator, lower, upper);
}
const HParser* h_ch_range__m(HAllocator* mm__, const uint8_t lower, const uint8_t upper) {
  HParser *ret = h_new(HParser, 1);
  HCharset cs = new_charset(mm__);
  for (int i = 0; i < 256; i++)
    charset_set(cs, i, (lower <= i) && (i <= upper));
  ret->vtable = &charset_vt;
  ret->env = (void*)cs;
  return (const HParser*)ret;
}


static const HParser* h_in_or_not__m(HAllocator* mm__, const uint8_t *options, size_t count, int val) {
  HParser *ret = h_new(HParser, 1);
  HCharset cs = new_charset(mm__);
  for (size_t i = 0; i < 256; i++)
    charset_set(cs, i, 1-val);
  for (size_t i = 0; i < count; i++)
    charset_set(cs, options[i], val);

  ret->vtable = &charset_vt;
  ret->env = (void*)cs;
  return (const HParser*)ret;
}

const HParser* h_in(const uint8_t *options, size_t count) {
  return h_in_or_not__m(&system_allocator, options, count, 1);
}

const HParser* h_in__m(HAllocator* mm__, const uint8_t *options, size_t count) {
  return h_in_or_not__m(mm__, options, count, 1);
}

const HParser* h_not_in(const uint8_t *options, size_t count) {
  return h_in_or_not__m(&system_allocator, options, count, 0);
}

const HParser* h_not_in__m(HAllocator* mm__, const uint8_t *options, size_t count) {
  return h_in_or_not__m(mm__, options, count, 0);
}