import { data } from "./main.ts";
import { tiles, players, PlayerData } from "./main.ts";
import { V2, normalize, length, sub_v2, lerp_exp_v2_mut } from "./util.ts";

export const PLAYER_SIZE = 0.4;

export function player_movement_update(p: PlayerData, dt: number, input: V2) {
    if (length(input) > 0.1) lerp_exp_v2_mut(p.facing, input, dt * 10.)
    p.rot = Math.atan2(p.facing.x, p.facing.y)
    p.vel.x += input.x * dt * 25
    p.vel.y += input.y * dt * 25
    p.x += p.vel.x * dt
    p.y += p.vel.y * dt
    collide_player(p, dt)
    lerp_exp_v2_mut(p.vel, { x: 0, y: 0 }, dt * 5.)
}

function collide_player(p: PlayerData, dt: number) {
    for (const [_, tile] of tiles) {
        if (!data.tile_collide[tile.kind]) continue

        const d = aabb_point_distance(tile.x, tile.y, tile.x + 1, tile.y + 1, p.x, p.y)
        if (d > PLAYER_SIZE) continue

        const h = 0.01
        const d_sample_x = aabb_point_distance(tile.x, tile.y, tile.x + 1, tile.y + 1, p.x + h, p.y)
        const d_sample_y = aabb_point_distance(tile.x, tile.y, tile.x + 1, tile.y + 1, p.x, p.y + h)
        const grad_x = (d_sample_x - d) / h
        const grad_y = (d_sample_y - d) / h

        p.x += (PLAYER_SIZE - d) * grad_x
        p.y += (PLAYER_SIZE - d) * grad_y

        const vdotn = (grad_x * p.vel.x) + (grad_y * p.vel.y)
        p.vel.x -= grad_x * vdotn
        p.vel.y -= grad_y * vdotn
    }

    for (const [_, player] of players) {
        const diff = sub_v2(p, player)
        const d = length(diff)
        if (d < 0.01) continue
        if (d >= PLAYER_SIZE * 2) continue
        const norm = normalize(diff);
        const f = 100 / (1 + d)
        p.vel.x += norm.x * f * dt
        p.vel.y += norm.y * f * dt
    }
}

export function aabb_point_distance(
    min_x: number,
    min_y: number,
    max_x: number,
    max_y: number,
    px: number,
    py: number
): number {
    const dx = px - Math.max(min_x, Math.min(max_x, px))
    const dy = py - Math.max(min_y, Math.min(max_y, py))
    return Math.sqrt(dx * dx + dy * dy)
}