#include "aoc.h"
#include "md5.h"
#include <map>
#include <set>

namespace aoc2016 {

struct md5_property {
  std::string md5;
  char c = 0;
};

static std::vector<md5_property> md5s;
static std::map<char, std::vector<size_t>> has5s;

static bool is_equal(const char* p0, const char* p1) {
  while (p0 < p1) {
    if (*p0 != *p1) {
      return false;
    }
    p0++;
  }
  return true;
}

const char* has(const char* md5, int n) {
  const char* p = md5;
  while (p < md5 + 32 - n + 1) {
    if (is_equal(p, p + n - 1)) {
      return p;
    }
    p++;
  }
  return nullptr;
}

static bool in_range(char c, size_t l, size_t h) {
  auto it = has5s.find(c);
  if (it != has5s.end()) {
    auto& v = it->second;
    size_t ll = v[0];
    size_t hh = v[v.size() - 1];
    auto is_in = [l, h](size_t x) { return x >= l && x <= h; };
    if (is_in(ll) || is_in(hh)) {
      return true;
    }
  }
  return false;
}

std::string stretching(const char* md5, size_t n) {
  std::string s{md5};
  while (n-- > 0) {
    s = std::string{md5sum((char*)s.c_str()), 32};
  }
  return s;
}

md5_property md5(const char* secret, size_t index) {
  if (index >= md5s.size()) {
    char buf[128] = {0};
    int l = strlen(secret);
    memcpy(buf, secret, l);
    auto s = md5s.size();
    md5s.resize(index + 1);
    for (size_t i = s; i < md5s.size(); i++) {
      sprintf(buf + l, "%zu", i);
      md5s[i].md5 = std::string(md5sum(buf), 32);
      // md5s[i].md5 = stretching(md5s[i].md5.c_str(), 2016);
      auto pc3 = has(md5s[i].md5.c_str(), 3);
      if (pc3 != nullptr) {
        md5s[i].c = *pc3;
        auto pc5 = has(md5s[i].md5.c_str(), 5);
        if (pc5 != nullptr) {
          // printf("%zu has 5 %c\n", i, *pc3);
          auto p = has5s.insert({*pc3, {i}});
          if (!p.second) {
            p.first->second.push_back(i);
          }
        }
      }
    }
  }
  return md5s[index];
}

size_t find_key(int* count, int max) {
  size_t i{0};
  while (*count < max && i < md5s.size()) {
    auto& p = md5s[i];
    if (p.c > 0 && in_range(p.c, i + 1, i + 1000)) {
      // printf("%zu %s with %c\n", i, p.md5.c_str(), p.c);
      *count += 1;
    }
    i++;
  }
  return i - 1;
}

std::pair<size_t, int64_t> day14(line_view) {
  // md5("abc", 30000);
  md5("jlmsuwbz", 50000);
  int count{0};
  auto i = find_key(&count, 64);
  return {i, 0};
}
} // namespace aoc2016