package main

import (
	"fmt"
	"math/rand"
)

func PlayGame(numPlayers int, entropy *rand.Rand) {

	currentPlayer := 0

	runningScores := make([]int, numPlayers)

	for round := 3; round < 14; round++ {

		r := NewRound(round, numPlayers, entropy)
		nextPlayer, roundScores := r.Play(currentPlayer)

		currentPlayer = nextPlayer

		for p := 0; p < numPlayers; p++ {
			runningScores[p] += roundScores[p]
		}

		fmt.Printf("The round has ended\n")
		fmt.Printf("Running total scores: %v\n", runningScores)
	}

	fmt.Printf("The game has ended\n")
}

type Round struct {
	d          []Card
	discard    []Card
	round      int
	numPlayers int
	hands      [][]Card
}

func NewRound(round, numPlayers int, entropy *rand.Rand) *Round {

	r := Round{
		round:      round,
		numPlayers: numPlayers,
	}

	r.d = Deck()
	Shuffle(r.d, entropy)

	r.discard = []Card{}

	fmt.Printf("# Round %d\n\n", r.round)

	// Deal starting cards

	r.hands = make([][]Card, numPlayers)
	for p := 0; p < numPlayers; p++ {
		r.hands[p] = make([]Card, round, round+1)
		copy(r.hands[p], r.d[0:round]) // Deal from the bottom (0)
		r.d = r.d[round:]

		fmt.Printf("P%d starting hand: %v\n", p, r.hands[p])
	}

	// Deal one into the discard pile

	r.discard = append(r.discard, r.d[0])
	r.d = r.d[1:]

	// Done

	return &r
}

func (r *Round) DrawFromDeck() Card {
	newCard := r.d[0]
	r.d = r.d[1:]
	return newCard
}

func (r *Round) PeekFromDiscard() Card {
	return r.discard[len(r.discard)-1]
}

func (r *Round) DrawFromDiscard() Card {
	newCard := r.discard[len(r.discard)-1]
	r.discard = r.discard[0 : len(r.discard)-1]

	return newCard
}

func (r *Round) AddToHand(player int, c Card) {
	r.hands[player] = append(r.hands[player], c)
}

func (r *Round) Discard(player, idx int) {
	unwantedCard := r.hands[player][idx]

	// Slice tricks: Copy end card into this slot and reslice bounds

	r.hands[player][idx] = r.hands[player][len(r.hands[player])-1]
	r.hands[player] = r.hands[player][0 : len(r.hands[player])-1]

	r.discard = append(r.discard, unwantedCard) // On top = available for next player
}

func (r *Round) Play(startingPlayer int) (nextPlayer int, roundScores []int) {

	currentPlayer := startingPlayer

	fmt.Printf("Discard stack: %v\n", r.discard)

	fmt.Printf("Deck has %d cards remaining\n", len(r.d))

	roundEndsWhenPlayerIs := -1

	for {
		if roundEndsWhenPlayerIs == currentPlayer {
			break
		}

		// Play the strategy for the current player
		r.PlayDefaultStrategy(currentPlayer)

		// Check, one more time, if we have a winning hand

		currentBestGrouping, currentScore := FindBestGrouping(r.hands[currentPlayer], r.round)
		if currentScore == 0 {

			// Declare victory
			fmt.Printf("P%d declares victory\n- Hand: %v\n- Groupings: %v\n- Summary: %v\n", currentPlayer, r.hands[currentPlayer], currentBestGrouping, FormatHandGroupings(r.hands[currentPlayer], currentBestGrouping))

			if roundEndsWhenPlayerIs == -1 {
				roundEndsWhenPlayerIs = currentPlayer
			} // Otherwise, the round is already ending anyway
		}

		// Move to the next player
		currentPlayer = (currentPlayer + 1) % r.numPlayers
	}

	// The round has ended
	// Figure out what each player scored

	roundScores = make([]int, r.numPlayers)

	for p := 0; p < r.numPlayers; p++ {

		gr, score := FindBestGrouping(r.hands[p], r.round)

		fmt.Printf("P%d has %v (score: %d)\n", p, FormatHandGroupings(r.hands[p], gr) /*r.hands[p], gr,*/, score)

		if roundEndsWhenPlayerIs == p && score != 0 {
			fmt.Printf("Expected player %d to have won, but they didn't?\n", p)
			panic("???")
		}

		roundScores[p] = score
	}

	// Check stack alignment
	if len(r.discard)+len(r.d)+(r.numPlayers*len(r.hands[0])) != DeckSize {
		panic("Cards on the floor")
	}

	// Done
	return currentPlayer, roundScores
}