/// <reference lib="dom" />

const ws = new WebSocket("/events")

type Packet = "tick"
    | { pos: { id: number, x: number, y: number } }
    | { game: { width: number, height: number } }
    | { player: { id: number, name: string } }
    | { die: number[] }
    | { win: [number, number] }
    | { chat: string }

class Snake {
    parts: { x: number, y: number, dx: number, dy: number }[] = []
    color: string
    dead = false
    constructor(public name: string) {
        this.color = name_color(name)
    }
    add_part(x: number, y: number) {
        if (!this.parts.length) return this.parts.push({ x, y, dx: 0, dy: 0 })
        const last = this.parts[this.parts.length - 1]
        let dx = x - last.x, dy = y - last.y;
        if (x > last.x + 1 || x < last.x - 1) dx *= -1, dx /= Math.abs(dx)
        if (y > last.y + 1 || y < last.y - 1) dy *= -1, dy /= Math.abs(dy)
        this.parts.push({ x, y, dx, dy })
    }
}

let size = 0
let tick_anim = 0;
const snakes = new Map<number, Snake>()

let canvas: HTMLCanvasElement
let ctx: CanvasRenderingContext2D

document.addEventListener("DOMContentLoaded", () => {
    canvas = document.createElement("canvas")
    ctx = canvas.getContext("2d")!
    document.getElementById("board")?.append(canvas)
    canvas.width = 1000;
    canvas.height = 1000;
    redraw()
})

function redraw() {
    ctx.fillStyle = "black"
    ctx.fillRect(0, 0, canvas.width, canvas.height);

    ctx.save()
    const scale = canvas.width / size
    ctx.scale(scale, scale)
    for (let x = 0; x < size; x++) {
        for (let y = 0; y < size; y++) {
            ctx.strokeStyle = "grey"
            ctx.lineWidth = 0.02
            ctx.strokeRect(x, y, 1, 1)
        }
    }
    ctx.translate(0.5, 0.5)
    for (const [xo, yo] of [[0, 0], [-size, 0], [size, 0], [0, -size], [0, size]]) {
        ctx.save()
        ctx.translate(xo, yo)
        for (const snake of snakes.values()) {
            ctx.beginPath();
            for (let i = 0; i < snake.parts.length; i++) {
                const p = snake.parts[i];
                ctx.moveTo(p.x - p.dx, p.y - p.dy)
                if (i == snake.parts.length - 1)
                    ctx.lineTo(tick_lerp(p.x - p.dx, p.x), tick_lerp(p.y - p.dy, p.y))
                else ctx.lineTo(p.x, p.y)
            }
            ctx.lineCap = "round"
            ctx.lineJoin = "round"
            if (snake.dead) ctx.lineWidth = tick_lerp(0.6, 0.001)
            else ctx.lineWidth = 0.6;
            ctx.strokeStyle = snake.color
            ctx.stroke()
        }
        ctx.restore()
    }
    ctx.restore()

    ctx.save()
    ctx.translate(scale / 2, scale / 4)
    for (const [xo, yo] of [[0, 0], [-size * scale, 0], [size * scale, 0], [0, -size * scale], [0, size * scale]]) {
        ctx.save()
        ctx.translate(xo, yo)
        for (const snake of snakes.values()) {
            const p = snake.parts[snake.parts.length - 1];
            if (!p) continue
            ctx.font = "30px sans-serif"
            if (snake.dead) ctx.fillStyle = `rgba(1,1,1,${tick_lerp(1, 0)})`
            else ctx.fillStyle = "white"
            ctx.textAlign = "center"
            ctx.textBaseline = "bottom"
            ctx.fillText(snake.name, tick_lerp(p.x - p.dx, p.x) * scale, tick_lerp(p.y - p.dy, p.y) * scale)
        }
        ctx.restore()
    }
    ctx.restore()

    tick_anim += 0.1
    tick_anim = Math.min(1, tick_anim)
    requestAnimationFrame(redraw)
}

function tick_lerp(f: number, t: number) {
    return (1 - tick_anim) * f + tick_anim * t
}

function name_color(name: string): string {
    let hash = 0;
    for (let i = 0; i < name.length; i++) {
        hash += name.charCodeAt(i);
        hash |= 0;
        hash ^= hash << 13;
        hash ^= hash >> 17;
        hash ^= hash << 5;
    }
    return `hsl(${hash % 360}deg 80% 40%)`;
}

ws.onerror = console.error
ws.onmessage = message => {
    const p = JSON.parse(message.data) as Packet
    if (p == "tick") {
        tick_anim = 0
        const d = []
        for (const [k, s] of snakes) {
            if (s.dead) d.push(k)
        }
        d.forEach(k => snakes.delete(k))
    } else if ("game" in p) {
        snakes.clear()
        size = p.game.width
    } else if ("win" in p) {
        const winner = snakes.get(p.win[0])?.name;
        if (winner) chat(`${winner} won this round.`, "win")
        else chat(`round ended in a tie.`, "tie")
    } else if ("player" in p) {
        snakes.set(p.player.id, new Snake(p.player.name))
    } else if ("pos" in p) {
        snakes.get(p.pos.id)?.add_part(p.pos.x, p.pos.y)
    } else if ("die" in p) {
        chat(`${p.die.map(e => snakes.get(e)?.name).join(", ")} died.`, "die")
        for (const d of p.die) {
            const s = snakes.get(d)
            if (s) s.dead = true
        }
    } else if ("chat" in p) {
        chat(p.chat)
    }
}

const chat_history: HTMLElement[] = [];
function chat(message: string, clas = "chat") {
    const e = document.createElement("p")
    e.textContent = message;
    e.classList.add("message")
    e.classList.add(clas)
    document.getElementById("chat_messages")!.prepend(e)
    chat_history.push(e);
    while (chat_history.length > 64) {
        chat_history.splice(0, 1).forEach(e => e.remove())
    }
}