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import { board } from "../board.js"
import { Vector2 } from "../engine/vector2.js"
import { PLAYER } from "../constants.js"
const SURROUNDING = [
new Vector2(-1, 0),
new Vector2(0, 1),
new Vector2(0, -1),
new Vector2(1, 0),
]
export function hasLiberties({
position,
team
}) {
if (getPiece(position) != undefined) return false
let groups = getSurroundingGroups(position, team)
groups.push(position)
let liberties = getGroupLiberties(groups)
liberties = removeIfInArray(position, liberties)
if (liberties.length == 0) {
let enemies = getGroupSurroundingEnemies(groups, team)
let enemyLiberties = getGroupLiberties(enemies)
enemyLiberties = removeIfInArray(position, enemyLiberties)
return (enemyLiberties.length == 0)
}
return (liberties.length > 0)
}
function removeIfInArray(value, array) {
return array.filter(x => !Vector2.equals(value, x))
}
function getLiberties(position) {
return getSurroundingSquares(position)
.filter(p => getPiece(p) == undefined)
}
function getGroupLiberties(group) {
let checkedPositions = []
group
.map(p => getLiberties(p))
.forEach(g => g
.forEach(p => pushIfNotInArray(p, checkedPositions))
)
return checkedPositions
}
function getGroupSurroundingEnemies(group, playerTeam) {
if (group.length == 0) return []
let team = playerTeam == PLAYER.BLACK ?
PLAYER.WHITE :
PLAYER.BLACK
let surroundingEnemies = group
.map(p => getSurroundingGroups(p, team))
if (surroundingEnemies.length == 0) return []
return surroundingEnemies
.reduce((partialArray = [], newGroup) => {
if (newGroup.length == 0) {
return partialArray
}
if (isInArray(newGroup[0], partialArray)) {
return partialArray
}
return partialArray.concat(newGroup)
})
}
function getSurroundingGroups(position, team) {
let surroundingGroups = getSurroundingSquares(position)
.filter(p => getPiece(p) != undefined)
.filter(p => getPiece(p).team == team)
.map(p => getGroup({position: p}))
if (surroundingGroups.length == 0) {
return []
}
return surroundingGroups
.reduce((partialArray = [], newGroup) => {
if (newGroup.length == 0) {
return partialArray
}
if (isInArray(newGroup[0], partialArray)) {
return partialArray
}
return partialArray.concat(newGroup)
})
}
function getGroup({position, checkedPositions = []}) {
if (isInArray(position, checkedPositions)) {
return
}
checkedPositions.push(position)
let team = getPiece(position).team
getSurroundingSquares(position)
.filter(p => getPiece(p) != undefined)
.filter(p => getPiece(p).team == team)
.forEach(p => {
getGroup({
position: p,
checkedPositions: checkedPositions
})
})
return checkedPositions
}
function getPiece(position) {
return board.stones[position.y][position.x]
}
function isInArray(position, array) {
return Array.from(array)
.some(p => Vector2.equals(p, position))
}
function pushIfNotInArray(position, array) {
if (!isInArray(position, array)) {
array.push(position)
}
}
function getSurroundingSquares(position) {
return Array.from(SURROUNDING)
.map(v => Vector2.sum(v, position))
.filter(z => 0 <= z.x && z.x < board.size &&
0 <= z.y && z.y < board.size
)
}
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