const root = @import("root.zig");
const rl = @cImport(@cInclude("raylib.h"));

const Animation = @This();

world_from: rl.Vector2,
world_to: rl.Vector2,
//distance: f32, // TODO frame independent durations
//speed: f32, // TODO frame independent durations
duration: u32,
tick: u32,
active: bool,

// this is wrong, just do per tile/node animations between path finding nodes
pub fn init(world_from: rl.Vector2, world_to: rl.Vector2, speed: u32) Animation {
    return Animation{
        .world_from = world_from,
        .world_to = world_to,
        //.distance = calc_distance(world_from, world_to),
        //.speed = speed,
        .duration = root.HexCoord.fakeDistance(root.HexCoord.worldToQr(world_from), root.HexCoord.worldToQr(world_to)) * 10 / speed, // TODO speed based duration
        .tick = 0,
        .active = true,
    };
}

pub fn next(self: *Animation) rl.Vector2 {
    if (self.tick >= self.duration) {
        self.active = false;
        return self.world_to;
    }

    self.tick += 1;
    return self.lerp();
}

inline fn calc_distance(from: rl.Vector2, to: rl.Vector2) f32 {
    return @abs(from.x - to.x) + @abs(from.x - to.y);
}

inline fn lerp(self: *Animation) rl.Vector2 {
    const t: f32 = @as(f32, @floatFromInt(self.tick)) / @as(f32, @floatFromInt(self.duration));
    const v1 = self.world_from;
    const v2 = self.world_to;
    return .{
        .x = v1.x + (t * (v2.x - v1.x)),
        .y = v1.y + (t * (v2.y - v1.y)),
    };
}