module main

import gg
import math.easing

const all = {
    'in_functions':     {
        'linear':     voidptr(easing.linear)
        'in_sine':    easing.in_sine
        'in_quad':    easing.in_quad
        'in_cubic':   easing.in_cubic
        'in_quart':   easing.in_quart
        'in_quint':   easing.in_quint
        'in_expo':    easing.in_expo
        'in_circ':    easing.in_circ
        'in_back':    easing.in_back
        'in_elastic': easing.in_elastic
        'in_bounce':  easing.in_bounce
    }
    'out_functions':    {
        'linear':      voidptr(easing.linear)
        'out_sine':    easing.out_sine
        'out_quad':    easing.out_quad
        'out_cubic':   easing.out_cubic
        'out_quart':   easing.out_quart
        'out_quint':   easing.out_quint
        'out_expo':    easing.out_expo
        'out_circ':    easing.out_circ
        'out_back':    easing.out_back
        'out_elastic': easing.out_elastic
        'out_bounce':  easing.out_bounce
    }
    'in_out_functions': {
        'linear':         voidptr(easing.linear)
        'in_out_sine':    easing.in_out_sine
        'in_out_quad':    easing.in_out_quad
        'in_out_cubic':   easing.in_out_cubic
        'in_out_quart':   easing.in_out_quart
        'in_out_quint':   easing.in_out_quint
        'in_out_expo':    easing.in_out_expo
        'in_out_circ':    easing.in_out_circ
        'in_out_back':    easing.in_out_back
        'in_out_elastic': easing.in_out_elastic
        'in_out_bounce':  easing.in_out_bounce
    }
}
const all_keys = all.keys()

@[heap]
struct App {
mut:
    gg   &gg.Context = unsafe { nil }
    x    f64
    t    f64
    h    f64
    kind string = all_keys.first()
}

fn (mut app App) draw_circle(label string, f easing.EasingFN) {
    offset := 30
    app.gg.draw_text_def(int(app.x) - 30, 5, label)
    app.gg.draw_line(f32(app.x), offset, f32(app.x), f32(app.h + offset), gg.gray)
    app.gg.draw_circle_filled(f32(app.x), f32(offset + f(app.t) * app.h), 10, gg.rgb(0, 0, 255))
    app.x += 120
}

fn (mut app App) frame() {
    size := gg.window_size()
    period := u64(240)
    app.t = f32_min(1.0, f32(app.gg.frame % period) / f32(period - 30))
    app.x = 80
    app.h = size.height - 100
    app.gg.begin()
    app.gg.draw_line(0, f32(app.h + 30), size.width, f32(app.h + 30), gg.gray)
    current_map := unsafe { all[app.kind].clone() }
    for k, e in current_map {
        app.draw_circle(k, e)
    }
    app.gg.draw_text_def(50, int(app.h + 50),
        'Note: use left and right arrows to change functions. Frame: ${app.gg.frame:010} | t: ${app.t:6.3f} | kind: ${app.kind}.')
    app.gg.end()
}

fn (mut app App) change_functions(direction int) {
    idx := (all_keys.len + all_keys.index(app.kind) + direction) % all_keys.len
    app.kind = all_keys[idx]
}

fn (mut app App) on_event(ev &gg.Event, _x voidptr) {
    if ev.typ != .key_down {
        return
    }
    if ev.key_code == .left {
        app.change_functions(-1)
    } else if ev.key_code == .right {
        app.change_functions(1)
    }
}

mut app := &App{}
app.gg = gg.new_context(
    bg_color:     gg.rgb(174, 198, 255)
    width:        1350
    height:       800
    window_title: 'Easing functions'
    frame_fn:     app.frame
    event_fn:     app.on_event
    user_data:    app
)
app.gg.run()