gist:6761915

## gistfile1.go
package main

import "fmt"

type Weapon interface {
    Strength() int
}
/* type KnightWeapon interface { */
    /* Weapon */
/* } */
/* type MagicianWeapon interface { */
    /* Weapon */
/* } */

type weapon struct {
    strength int
}
func (w *weapon) Strength() int {
    return w.strength
}
type knightWeapon struct {
    *weapon
}
type magicianWeapon struct {
    *weapon
}

var NullWeapon *weapon = &weapon{0}
var LongSword *knightWeapon = &knightWeapon{ &weapon{8} }
var Rod *magicianWeapon = &magicianWeapon{ &weapon{2} }


type HasWeapon interface {
    Weapon() Weapon
}

type Player interface {
    HasWeapon
    Name() string
    Attack(otherPlayer Player)
    Damaged(damage int)
    IsDead() bool
}
type player struct {
    name string
    hp int
    mp int
    strength int
    weapon Weapon
}
func (p *player) Name() string {
    return p.name
}
func (p *player) Weapon() Weapon {
    return p.weapon
}
func (p *player) Attack(otherPlayer Player) {
    fmt.Printf("%sは%sを攻撃した\n", p.name, otherPlayer.Name())
    damage := p.strength + p.Weapon().Strength()
    otherPlayer.Damaged(damage)
}
func (p *player) Damaged(damage int) {
    fmt.Printf("=> %sは%dのダメージを受けた\n", p.name, damage)

    if p.hp - damage < 0 {
        p.hp = 0
    } else {
        p.hp -= damage
    }

    if p.IsDead() {
        fmt.Printf("%sはしんでしまった\n", p.name)
    }
}
func (p *player) IsDead() bool {
    return p.hp <= 0
}

type CanEquip interface {
    Equip(w Weapon)
}

type Knight interface {
    Player
    CanEquip
}
type knight struct {
    *player
}
func (p *knight) Equip(w Weapon) {
    switch w.(type) {
    case *knightWeapon:
        p.weapon = w
    }
}

func NewKnightPlayer(name string) Knight {
    knight := &knight{ &player{ name: name, hp: 20, mp: 0, strength: 5, weapon: NullWeapon } }
    return knight
}

type Magician interface {
    Player
    CanEquip
    Mera(player Player)
}
type magician struct {
    *player
}
func (p *magician) Equip(w Weapon) {
    switch w.(type) {
    case *magicianWeapon:
        p.weapon = w
    }
}
func (p *magician) Mera(otherPlayer Player) {
    fmt.Printf("%sはメラを唱えた\n", p.name)

    if p.mp < 3 {
            fmt.Printf("...しかしMPが足りない！！\n")
    } else {
        p.mp -= 3
        otherPlayer.Damaged(10)
    }
}

func NewMagicianPlayer(name string) Magician {
    magician := &magician{ &player{ name: name, hp: 15, mp: 5, strength: 3, weapon: NullWeapon } }
    return magician
}

func main() {
    shinpei := NewMagicianPlayer("しんぺい")
    takashi := NewKnightPlayer("たかし")

    shinpei.Equip(Rod)
    takashi.Equip(LongSword)

    shinpei.Mera(takashi)
    takashi.Attack(shinpei)
    shinpei.Mera(takashi)
    takashi.Attack(shinpei)
}