Go Fish/Go

The AI selects cards randomly from its hand.

```package main

import (
"fmt"
"math/rand"
"sort"
"time"
)

var cards = [13]string{"2", "3", "4", "5", "6", "7", "8", "9",
"10", "J", "Q", "K", "A"}

//GoFishGame Stores the game state.
type GoFishGame struct {
hands  [][]string
deck   []string
turn   int
scores []int
}

// checkForBooks looks for fours of a kind
// and scores them if we have them.
// If we run out of cards, we draw more.
func (gm *GoFishGame) checkForBooks() {
sort.Strings(gm.hands[gm.turn])
prev := ""
count := 1
for _, card := range gm.hands[gm.turn] {
if card == prev {
count++
if count == 4 {
fmt.Printf("Book of %s.\n", card)
gm.stealCards(card, gm.turn)
gm.scores[gm.turn]++
if gm.isHandEmpty() {
gm.drawCard()
}
}
} else {
count = 1
}
prev = card
}
}

// drawCard takes a card from the deck
// adding it to the current player's hand.
func (gm *GoFishGame) drawCard() {
if !gm.isDeckEmpty() {
card := gm.deck[0]
gm.deck = gm.deck[1:]
if gm.isPlayerTurn() {
fmt.Printf("You drew a %s.\n", card)
}
gm.hands[gm.turn] = append(gm.hands[gm.turn], card)
//Check for books
gm.checkForBooks()
}
}

// getPickComputer handles the computer's card choices.
// We do the moderately smart thing of pick a random
// card from our hand
func getPickComputer(gm *GoFishGame) string {
hand := gm.hands[1]
choice := "A"
if len(hand) > 0 {
choice = hand[rand.Intn(len(hand))]
}
fmt.Printf("Computer picks %s.\n", choice)
return choice
}

// getPickUser gets the user's move.
// If it's not valid, then the user just wastes
// their turn.
func getPickUser(gm *GoFishGame) string {
fmt.Println("What card do you want?")
var card string
fmt.Scanf("%s\n", &card)
return card
}

// isDeckEmpty returns if the deck is empty.
func (gm *GoFishGame) isDeckEmpty() bool {
return len(gm.deck) == 0
}

// isHandEmpty returns if the current player's hand is empty.
func (gm *GoFishGame) isHandEmpty() bool {
return len(gm.hands[gm.turn]) == 0
}

// isGameOver returns if the game is over.
// This happens when all 13 pips have been made into sets.
func (gm *GoFishGame) isGameOver() bool {
return gm.scores[0]+gm.scores[1] == 13
}

// isPlayerTurn returns if its the player's turn to move.
func (gm *GoFishGame) isPlayerTurn() bool {
return gm.turn == 0
}

// makeDeck makes a deck.
// The deck is 52 cards with 4 of each pip.
func makeDeck() []string {
rand.Seed(time.Now().UTC().UnixNano())
deck := make([]string, 52)
perm := rand.Perm(52)
for indx := range perm {
tVal := perm[indx]
card := cards[tVal/4]
deck[indx] = card
}
return deck
}

// opponentHas returns if the opponent's hand has a card.
func (gm *GoFishGame) opponentHas(find string) bool {
for _, card := range gm.hands[(gm.turn+1)%2] {
if card == find {
return true
}
}
return false
}

// playerTurn handles the major game logic.
// It's used for both the player's and computer's turns,
// with the different behavior handled by the getPick param.
func (gm *GoFishGame) playerTurn(getPick func(*GoFishGame) string) {
opponent := (gm.turn + 1) % 2
gm.checkForBooks()
if opponent == 1 {
gm.printHand()
}
if gm.isHandEmpty() {
gm.drawCard()
}
gameOver := gm.isGameOver()
if !gameOver {
card := getPick(gm)
if gm.opponentHas(card) {
count := gm.stealCards(card, opponent)
for indx := 0; indx < count; indx++ {
gm.hands[gm.turn] = append(gm.hands[gm.turn], card)
}
gm.checkForBooks()
} else {
fmt.Println("GO FISH!")
gm.drawCard()
gm.turn = opponent
}
}
}

// printGameOverMessage prints the appropriate end message.
func (gm *GoFishGame) printGameOverMessage() {
fmt.Printf("Final score is %d to %d.\n", gm.scores[0], gm.scores[1])
if gm.scores[0] > gm.scores[1] {
fmt.Println("Player wins!")
} else if gm.scores[0] == gm.scores[1] {
fmt.Println("It's a tie.")
} else {
fmt.Println("Computer wins!")
}
}

// printHand print's the player's hand and current score.
func (gm *GoFishGame) printHand() {
sort.Strings(gm.hands[0])
fmt.Printf("You have: %s.\n", gm.hands[0])
fmt.Printf("Score is %d to %d.\n", gm.scores[0], gm.scores[1])
}

// stealCards removes all instances of a card from side's hand.
func (gm *GoFishGame) stealCards(purge string, side int) int {
count := 0
var filtered []string
for _, card := range gm.hands[side] {
if purge == card {
count++
} else {
filtered = append(filtered, card)
}
}
gm.hands[side] = filtered
return count
}

// main creates the deck and initial hands.
func main() {
deck := makeDeck()
playerHand := deck[0:9]
compHand := deck[9:18]
deck = deck[18:]
hands := make([][]string, 2, 2)
hands[0] = playerHand
hands[1] = compHand
scores := make([]int, 2, 2)
scores[0] = 0
scores[1] = 0
game := GoFishGame{hands, deck, 0, scores}
for {
if game.isPlayerTurn() {
game.playerTurn(getPickUser)
} else {
game.playerTurn(getPickComputer)
}
if game.isGameOver() {
break
}
}
game.printGameOverMessage()

}
```