const [LEFT, RIGHT, UP, DOWN, SIT] = [0, 1, 2, 3, 4]

const state = {walls: [], visited: [], ctx: null, me: {}}

const drawBox = (x, y, color) => {
    const {ctx, S} = state
    ctx.fillStyle = color
    ctx.fillRect(S * x, S * y, S, S)
    
}

AB.mind.newRun = function() {
    const N = 20
    const S = 20 //scale
    state.walls = Array(N).fill(0).map(_ => Array(N).fill(0))
    state.visited = Array(N).fill(0).map(_ => Array(N).fill(-1))
        
    const $ = id => document.getElementById(id)
    const map = document.createElement('canvas')
    map.height = map.width = N * S
    map.style.background = 'darkgray'
    map.style.height = map.style.width = N * S + 'px'
    const ctx = map.getContext('2d')
    ctx.fillStyle = 'grey'
    ctx.fillRect(1 * S, 1 * S, N * S - 2 * S, N * S - 2 * S)
    $('ab-runheaderbox').appendChild(map)
    
    for (let i = 0; i < N; i++)
        state.walls[i][0] = state.walls[0][i] = state.walls[i][N - 1] = state.walls[N - 1][i] = 1

    state.ctx = ctx
    state.N = N
    state.S = S
    
}

AB.mind.endRun = function() {}


AB.mind.getAction = function(pos) {
    const [meX, meY, enemyX, enemyY] = pos
    const {visited, walls, ctx, N, S, me } = state
    
    visited[meY][meX]++
    visited[enemyY][enemyX] == -1 && visited[enemyY][enemyX]++

    if(!me.hasMoved) {
        me.hasMoved = true
        me.x = meX
        me.y = meY
        return me.action = LEFT
    }
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    
    // threat enemy position as a temporary wall
    walls[enemyY][enemyX] = 1
    
    if(me.x == meX && me.y == meY) { // hasn't moved
        const y = meY + (me.action == UP ? 1 : (me.action == DOWN ? -1 : 0))
        const x = meX + (me.action == LEFT ? -1 : (me.action == RIGHT ? 1 : 0))

        walls[y][x] = 1
    }
    const todo = [
        {y: meY, x: meX - 1}, // left
        {y: meY, x: meX + 1}, // right
        {y: meY + 1, x: meX}, // up
        {y: meY - 1, x: meX} // down
    ]
    
    let action = {type: SIT, visited: Infinity}

    for(let i = 0; i < todo.length; i++) {
        
        const move = todo[i]
        
        if(walls[move.y][move.x]) continue;

        const visit = visited[move.y][move.x]
        if(visit < action.visited) {
            action.type = i
            action.visited = visit
        }
    }

    me.x = meX
    me.y = meY
    me.action = action.type
    
    // threat enemy position as a temporary wall
    walls[enemyY][enemyX] = 0


    ctx.clearRect(0, 0, ctx.canvas.width, ctx.canvas.height)
    const MAX_VISITED = Math.max(...visited.map(row => Math.max(...row)))
    for(let y = 0; y < N; y++) {
        for(let x = 0; x < N; x++) {
            walls[y][x] && drawBox(x, y, 'yellow')
            visited[y][x] != -1 && drawBox(x, y, `hsl(192, 90%, ${Math.max(56, parseInt(99 - 99 * visited[y][x] / MAX_VISITED))}%)`)
            
        }
    }
    drawBox(enemyX, enemyY, 'red')
    drawBox(meX, meY, 'green')
    return me.action
    
};