#include "eval.h"
#include <assert.h>
#include <stdio.h>
#include <stdlib.h>

int card_ptr_comp(const void *vp1, const void *vp2) {
  const card_t *const *cp1 = vp1;
  const card_t *const *cp2 = vp2;

  if ((*cp1)->value != (*cp2)->value) {
    return (*cp2)->value - (*cp1)->value;
  }

  return (*cp2)->suit - (*cp1)->suit;
}

suit_t flush_suit(deck_t *hand) {
  int numClub = 0;
  int numDiamond = 0;
  int numHeart = 0;
  int numSpade = 0;

  for (size_t i = 0; i < hand->n_cards; i++) {
    switch (hand->cards[i]->suit) {
    case SPADES:
      numSpade++;
      break;
    case HEARTS:
      numHeart++;
      break;
    case DIAMONDS:
      numDiamond++;
      break;
    default:
      numClub++;
    }
  }

  if (numSpade >= 5) {
    return SPADES;
  }
  if (numHeart >= 5) {
    return HEARTS;
  }
  if (numDiamond >= 5) {
    return DIAMONDS;
  }
  if (numClub >= 5) {
    return CLUBS;
  }
  return NUM_SUITS;
}

unsigned get_largest_element(unsigned *arr, size_t n) {
  if (n == 0) {
    return 0;
  }
  unsigned ans = arr[0];
  for (size_t i = 1; i < n; i++) {
    if (arr[i] > ans) {
      ans = arr[i];
    }
  }
  return ans;
}

size_t get_match_index(unsigned *match_counts, size_t n, unsigned n_of_akind) {

  for (size_t i = 0; i < n; i++) {
    if (match_counts[i] == n_of_akind) {
      return i;
    }
  }
  assert(1 == 2);
}

ssize_t find_secondary_pair(deck_t *hand, unsigned *match_counts,
                            size_t match_idx) {

  for (size_t i = 0; i < hand->n_cards; i++) {
    if (match_counts[i] > 1) {
      if (hand->cards[i]->value != hand->cards[match_idx]->value) {
        return i;
      }
    }
  }
  return -1;
}

int is_ace_low_straight_at_five(deck_t *hand, size_t index, suit_t fs) {
  int straightTally = 2;
  int currentCardValue = 5;
  for (size_t i = index + 1; i < hand->n_cards; i++) {
    if (straightTally == 5) {
      return -1;
    }

    if (hand->cards[i]->value == currentCardValue) {
      continue;
    }

    if (hand->cards[i]->value == currentCardValue - 1) {
      if (fs == NUM_SUITS || hand->cards[i]->suit == fs) {
        straightTally++;
        currentCardValue--;
      } else {
        continue;
      }
    } else {
      break;
    }
  }
  if (straightTally == 5) {
    return -1;
  }
  return 0;
}

int is_ace_low_straight_at(deck_t *hand, size_t index, suit_t fs) {
  int currentCardValue = hand->cards[index]->value;
  if (currentCardValue == 5) {
    return is_ace_low_straight_at_five(hand, index, fs);
  }

  if (currentCardValue == VALUE_ACE) {
    for (size_t i = index + 1; i < hand->n_cards; i++) {

      if (hand->cards[i]->value == currentCardValue) {
        continue;
      }

      if (hand->cards[i]->value == 5) {
        return is_ace_low_straight_at_five(hand, i, fs);
      }
    }
  }

  return 0;
}

int is_straight_at(deck_t *hand, size_t index, suit_t fs) {
  if (hand->cards[index]->suit != fs && fs != NUM_SUITS) {
    return 0;
  }
  int currentCardValue = hand->cards[index]->value;
  if (currentCardValue < 5) {
    return 0;
  }
  if (currentCardValue == 5) {
    if (hand->cards[0]->value != 14) {
      return 0;
    } else {
      return is_ace_low_straight_at(hand, index, fs);
    }
  }

  int straightTally = 1;
  for (size_t i = index + 1; i < hand->n_cards; i++) {
    if (straightTally == 5) {
      return 1;
    }

    if (hand->cards[i]->value == currentCardValue) {
      continue;
    }

    if (hand->cards[i]->value == currentCardValue - 1) {
      if (fs == NUM_SUITS || hand->cards[i]->suit == fs) {
        straightTally++;
        currentCardValue--;
      } else {
        continue;
      }
    } else {
      break;
    }
  }
  if (straightTally == 5) {
    return 1;
  }

  if (hand->cards[index]->value == VALUE_ACE) {
    return is_ace_low_straight_at(hand, index, fs);
  } else {
    return 0;
  }
}

hand_eval_t build_hand_from_match(deck_t *hand, unsigned n, hand_ranking_t what,
                                  size_t idx) {

  hand_eval_t ans;
  ans.ranking = what;
  for (int i = 0; i < n; i++) {
    ans.cards[i] = hand->cards[idx + i];
  }

  if (idx == 0) {
    for (int i = n; i < 5; i++) {
      ans.cards[i] = hand->cards[i];
    }
  } else if (idx >= 5 - n) {
    for (int i = 0; i < 5 - n; i++) {
      ans.cards[n + i] = hand->cards[i];
    }
  } else {
    for (int i = 0; i < idx; i++) {
      ans.cards[n + i] = hand->cards[i];
    }
    for (int i = idx + n; i < 5; i++) {
      ans.cards[i] = hand->cards[i];
    }
  }
  return ans;
}

int compare_hands(deck_t *hand1, deck_t *hand2) {

  qsort(hand1->cards, hand1->n_cards, sizeof(card_t), card_ptr_comp);
  qsort(hand2->cards, hand2->n_cards, sizeof(card_t), card_ptr_comp);
  hand_eval_t ht1 = evaluate_hand(hand1);
  hand_eval_t ht2 = evaluate_hand(hand2);

  if (ht1.ranking != ht2.ranking) {
    return ht2.ranking - ht1.ranking;
  }

  for (int i = 0; i < 5; i++) {
    if (ht1.cards[i]->value == ht2.cards[i]->value) {
      continue;
    } else {
      return ht1.cards[i]->value - ht2.cards[i]->value;
    }
  }
  return 0;
}

// You will write this function in Course 4.
// For now, we leave a prototype (and provide our
// implementation in eval-c4.o) so that the
// other functions we have provided can make
// use of get_match_counts.
unsigned *get_match_counts(deck_t *hand);

// We provide the below functions.  You do NOT need to modify them
// In fact, you should not modify them!

// This function copies a straight starting at index "ind" from deck "from".
// This copies "count" cards (typically 5).
// into the card array "to"
// if "fs" is NUM_SUITS, then suits are ignored.
// if "fs" is any other value, a straight flush (of that suit) is copied.
void copy_straight(card_t **to, deck_t *from, size_t ind, suit_t fs,
                   size_t count) {
  assert(fs == NUM_SUITS || from->cards[ind]->suit == fs);
  unsigned nextv = from->cards[ind]->value;
  size_t to_ind = 0;
  while (count > 0) {
    assert(ind < from->n_cards);
    assert(nextv >= 2);
    assert(to_ind < 5);
    if (from->cards[ind]->value == nextv &&
        (fs == NUM_SUITS || from->cards[ind]->suit == fs)) {
      to[to_ind] = from->cards[ind];
      to_ind++;
      count--;
      nextv--;
    }
    ind++;
  }
}

// This looks for a straight (or straight flush if "fs" is not NUM_SUITS)
// in "hand".  It calls the student's is_straight_at for each possible
// index to do the work of detecting the straight.
// If one is found, copy_straight is used to copy the cards into
// "ans".
int find_straight(deck_t *hand, suit_t fs, hand_eval_t *ans) {
  if (hand->n_cards < 5) {
    return 0;
  }
  for (size_t i = 0; i <= hand->n_cards - 5; i++) {
    int x = is_straight_at(hand, i, fs);
    if (x != 0) {
      if (x < 0) { // ace low straight
        assert(hand->cards[i]->value == VALUE_ACE &&
               (fs == NUM_SUITS || hand->cards[i]->suit == fs));
        ans->cards[4] = hand->cards[i];
        size_t cpind = i + 1;
        while (hand->cards[cpind]->value != 5 ||
               !(fs == NUM_SUITS || hand->cards[cpind]->suit == fs)) {
          cpind++;
          assert(cpind < hand->n_cards);
        }
        copy_straight(ans->cards, hand, cpind, fs, 4);
      } else {
        copy_straight(ans->cards, hand, i, fs, 5);
      }
      return 1;
    }
  }
  return 0;
}

// This function puts all the hand evaluation logic together.
// This function is longer than we generally like to make functions,
// and is thus not so great for readability :(
hand_eval_t evaluate_hand(deck_t *hand) {
  suit_t fs = flush_suit(hand);
  hand_eval_t ans;
  if (fs != NUM_SUITS) {
    if (find_straight(hand, fs, &ans)) {
      ans.ranking = STRAIGHT_FLUSH;
      return ans;
    }
  }
  unsigned *match_counts = get_match_counts(hand);
  unsigned n_of_a_kind = get_largest_element(match_counts, hand->n_cards);
  assert(n_of_a_kind <= 4);
  size_t match_idx = get_match_index(match_counts, hand->n_cards, n_of_a_kind);
  ssize_t other_pair_idx = find_secondary_pair(hand, match_counts, match_idx);
  free(match_counts);
  if (n_of_a_kind == 4) { // 4 of a kind
    return build_hand_from_match(hand, 4, FOUR_OF_A_KIND, match_idx);
  } else if (n_of_a_kind == 3 && other_pair_idx >= 0) { // full house
    ans = build_hand_from_match(hand, 3, FULL_HOUSE, match_idx);
    ans.cards[3] = hand->cards[other_pair_idx];
    ans.cards[4] = hand->cards[other_pair_idx + 1];
    return ans;
  } else if (fs != NUM_SUITS) { // flush
    ans.ranking = FLUSH;
    size_t copy_idx = 0;
    for (size_t i = 0; i < hand->n_cards; i++) {
      if (hand->cards[i]->suit == fs) {
        ans.cards[copy_idx] = hand->cards[i];
        copy_idx++;
        if (copy_idx >= 5) {
          break;
        }
      }
    }
    return ans;
  } else if (find_straight(hand, NUM_SUITS, &ans)) { // straight
    ans.ranking = STRAIGHT;
    return ans;
  } else if (n_of_a_kind == 3) { // 3 of a kind
    return build_hand_from_match(hand, 3, THREE_OF_A_KIND, match_idx);
  } else if (other_pair_idx >= 0) { // two pair
    assert(n_of_a_kind == 2);
    ans = build_hand_from_match(hand, 2, TWO_PAIR, match_idx);
    ans.cards[2] = hand->cards[other_pair_idx];
    ans.cards[3] = hand->cards[other_pair_idx + 1];
    if (match_idx > 0) {
      ans.cards[4] = hand->cards[0];
    } else if (other_pair_idx > 2) { // if match_idx is 0, first pair is in 01
      // if other_pair_idx > 2, then, e.g. A A K Q Q
      ans.cards[4] = hand->cards[2];
    } else { // e.g., A A K K Q
      ans.cards[4] = hand->cards[4];
    }
    return ans;
  } else if (n_of_a_kind == 2) {
    return build_hand_from_match(hand, 2, PAIR, match_idx);
  }
  return build_hand_from_match(hand, 0, NOTHING, 0);
}