// Copyright (c) 2020 Lars Pontoppidan. All rights reserved.
// Use of this source code is governed by the MIT license distributed with this software.
import term
import term.ui
import time

enum Mode {
    menu
    game
}

const player_one = 1 // Human control this racket

const player_two = 0 // Take over this AI controller

const white = ui.Color{255, 255, 255}

@[heap]
struct App {
mut:
    tui    &ui.Context = unsafe { nil }
    mode   Mode        = Mode.menu
    width  int
    height int
    game   &Game = unsafe { nil }
    dt     f32
    ticks  i64
}

fn (mut a App) init() {
    a.game = &Game{
        app: a
    }
    w, h := a.tui.window_width, a.tui.window_height
    a.width = w
    a.height = h
    term.erase_del_clear()
    term.set_cursor_position(
        x: 0
        y: 0
    )
}

fn (mut a App) start_game() {
    if a.mode != .game {
        a.mode = .game
    }
    a.game.init()
}

fn (mut a App) frame() {
    ticks := time.ticks()
    a.dt = f32(ticks - a.ticks) / 1000.0
    a.width, a.height = a.tui.window_width, a.tui.window_height
    if a.mode == .game {
        a.game.update()
    }
    a.tui.clear()
    a.render()
    a.tui.flush()
    a.ticks = ticks
}

fn (mut a App) quit() {
    if a.mode != .menu {
        a.game.quit()
        return
    }
    term.set_cursor_position(
        x: 0
        y: 0
    )
    exit(0)
}

fn (mut a App) event(e &ui.Event) {
    match e.typ {
        .mouse_move {
            if a.mode != .game {
                return
            }
            // TODO: mouse movement for real Pong sharks
            // a.game.move_player(player_one, 0, -1)
        }
        .key_down {
            match e.code {
                .escape, .q {
                    a.quit()
                }
                .w {
                    if a.mode != .game {
                        return
                    }
                    a.game.move_player(player_one, 0, -1)
                }
                .a {
                    if a.mode != .game {
                        return
                    }
                    a.game.move_player(player_one, 0, -1)
                }
                .s {
                    if a.mode != .game {
                        return
                    }
                    a.game.move_player(player_one, 0, 1)
                }
                .d {
                    if a.mode != .game {
                        return
                    }
                    a.game.move_player(player_one, 0, 1)
                }
                .left {
                    if a.mode != .game {
                        return
                    }
                    a.game.move_player(player_two, 0, -1)
                }
                .right {
                    if a.mode != .game {
                        return
                    }
                    a.game.move_player(player_two, 0, 1)
                }
                .up {
                    if a.mode != .game {
                        return
                    }
                    a.game.move_player(player_two, 0, -1)
                }
                .down {
                    if a.mode != .game {
                        return
                    }
                    a.game.move_player(player_two, 0, 1)
                }
                .enter, .space {
                    if a.mode == .menu {
                        a.start_game()
                    }
                }
                else {}
            }
        }
        else {}
    }
}

fn (mut a App) free() {
    unsafe {
        a.game.free()
        free(a.game)
    }
}

fn (mut a App) render() {
    match a.mode {
        .menu { a.draw_menu() }
        else { a.draw_game() }
    }
}

fn (mut a App) draw_menu() {
    cx := int(f32(a.width) * 0.5)
    y025 := int(f32(a.height) * 0.25)
    y075 := int(f32(a.height) * 0.75)
    cy := int(f32(a.height) * 0.5)

    a.tui.set_color(white)
    a.tui.bold()
    a.tui.draw_text(cx - 2, y025, 'VONG')
    a.tui.reset()
    a.tui.draw_text(cx - 13, y025 + 1, '(A game of Pong written in V)')

    a.tui.set_color(white)
    a.tui.bold()
    a.tui.draw_text(cx - 3, cy + 1, 'START')
    a.tui.reset()

    a.tui.draw_text(cx - 9, y075 + 1, 'Press SPACE to start')
    a.tui.reset()
    a.tui.draw_text(cx - 5, y075 + 3, 'ESC to Quit')
    a.tui.reset()
}

fn (mut a App) draw_game() {
    a.game.draw()
}

struct Player {
mut:
    game        &Game = unsafe { nil }
    pos         Vec
    racket_size int = 4
    score       int
    ai          bool
}

fn (mut p Player) move(x f32, y f32) {
    p.pos.x += x
    p.pos.y += y
}

fn (mut p Player) update() {
    if !p.ai {
        return
    }
    if isnil(p.game) {
        return
    }
    // dt := p.game.app.dt
    ball := unsafe { &p.game.ball }
    // Evil AI that eventually will take over the world
    p.pos.y = ball.pos.y - f32(p.racket_size) * 0.5
}

struct Vec {
mut:
    x f32
    y f32
}

fn (mut v Vec) set(x f32, y f32) {
    v.x = x
    v.y = y
}

struct Ball {
mut:
    pos Vec
    vel Vec
    acc Vec
}

fn (mut b Ball) update(dt f32) {
    b.pos.x += b.vel.x * b.acc.x * dt
    b.pos.y += b.vel.y * b.acc.y * dt
}

@[heap]
struct Game {
mut:
    app     &App = unsafe { nil }
    players []Player
    ball    Ball
}

fn (mut g Game) move_player(id int, x int, y int) {
    mut p := unsafe { &g.players[id] }
    if p.ai { // disable AI when moved
        p.ai = false
    }
    p.move(x, y)
}

fn (mut g Game) init() {
    if g.players.len == 0 {
        g.players = []Player{len: 2, init: Player{ // <- BUG omitting the init will result in smaller racket sizes???
            game: g
        }}
    }
    g.reset()
}

fn (mut g Game) reset() {
    mut i := 0
    for mut p in g.players {
        p.score = 0
        if i != player_one {
            p.ai = true
        }
        i++
    }
    g.new_round()
}

fn (mut g Game) new_round() {
    mut i := 0
    for mut p in g.players {
        p.pos.x = if i == 0 { f32(3) } else { f32(g.app.width - 2) }
        p.pos.y = f32(g.app.height) * 0.5 - f32(p.racket_size) * 0.5
        i++
    }
    g.ball.pos.set(f32(g.app.width) * 0.5, f32(g.app.height) * 0.5)
    g.ball.vel.set(-8, -15)
    g.ball.acc.set(2.0, 1.0)
}

fn (mut g Game) update() {
    dt := g.app.dt
    mut b := unsafe { &g.ball }
    for mut p in g.players {
        p.update()
        // Keep rackets within the game area
        if p.pos.y <= 0 {
            p.pos.y = 1.0
        }
        if p.pos.y + p.racket_size >= g.app.height {
            p.pos.y = f32(g.app.height - p.racket_size - 1)
        }
        // Check ball collision
        // Player left side
        if p.pos.x < f32(g.app.width) * 0.5 {
            // Racket collision
            if b.pos.x <= p.pos.x + 1 {
                if b.pos.y >= p.pos.y && b.pos.y <= p.pos.y + p.racket_size {
                    b.vel.x *= -1
                }
            }
            // Behind racket
            if b.pos.x < p.pos.x {
                g.players[1].score++
                g.new_round()
            }
        } else {
            // Player right side
            if b.pos.x >= p.pos.x - 1 {
                if b.pos.y >= p.pos.y && b.pos.y <= p.pos.y + p.racket_size {
                    b.vel.x *= -1
                }
            }
            if b.pos.x > p.pos.x {
                g.players[0].score++
                g.new_round()
            }
        }
    }
    if b.pos.x <= 1 || b.pos.x >= g.app.width {
        b.vel.x *= -1
    }
    if b.pos.y <= 2 || b.pos.y >= g.app.height {
        b.vel.y *= -1
    }
    b.update(dt)
}

fn (mut g Game) quit() {
    if g.app.mode != .game {
        return
    }
    g.app.mode = .menu
}

fn (mut g Game) draw_big_digit(px f32, py f32, digit int) {
    // TODO: use draw_line or draw_point to fix tearing with non-monospaced terminal fonts
    mut gfx := g.app.tui
    x, y := int(px), int(py)
    match digit {
        0 {
            gfx.draw_text(x, y + 0, '█████')
            gfx.draw_text(x, y + 1, '█   █')
            gfx.draw_text(x, y + 2, '█   █')
            gfx.draw_text(x, y + 3, '█   █')
            gfx.draw_text(x, y + 4, '█████')
        }
        1 {
            gfx.draw_text(x + 3, y + 0, '█')
            gfx.draw_text(x + 3, y + 1, '█')
            gfx.draw_text(x + 3, y + 2, '█')
            gfx.draw_text(x + 3, y + 3, '█')
            gfx.draw_text(x + 3, y + 4, '█')
        }
        2 {
            gfx.draw_text(x, y + 0, '█████')
            gfx.draw_text(x, y + 1, '    █')
            gfx.draw_text(x, y + 2, '█████')
            gfx.draw_text(x, y + 3, '█')
            gfx.draw_text(x, y + 4, '█████')
        }
        3 {
            gfx.draw_text(x, y + 0, '█████')
            gfx.draw_text(x, y + 1, '   ██')
            gfx.draw_text(x, y + 2, ' ████')
            gfx.draw_text(x, y + 3, '   ██')
            gfx.draw_text(x, y + 4, '█████')
        }
        4 {
            gfx.draw_text(x, y + 0, '█   █')
            gfx.draw_text(x, y + 1, '█   █')
            gfx.draw_text(x, y + 2, '█████')
            gfx.draw_text(x, y + 3, '    █')
            gfx.draw_text(x, y + 4, '    █')
        }
        5 {
            gfx.draw_text(x, y + 0, '█████')
            gfx.draw_text(x, y + 1, '█')
            gfx.draw_text(x, y + 2, '█████')
            gfx.draw_text(x, y + 3, '    █')
            gfx.draw_text(x, y + 4, '█████')
        }
        6 {
            gfx.draw_text(x, y + 0, '█████')
            gfx.draw_text(x, y + 1, '█')
            gfx.draw_text(x, y + 2, '█████')
            gfx.draw_text(x, y + 3, '█   █')
            gfx.draw_text(x, y + 4, '█████')
        }
        7 {
            gfx.draw_text(x, y + 0, '█████')
            gfx.draw_text(x, y + 1, '    █')
            gfx.draw_text(x, y + 2, '    █')
            gfx.draw_text(x, y + 3, '    █')
            gfx.draw_text(x, y + 4, '    █')
        }
        8 {
            gfx.draw_text(x, y + 0, '█████')
            gfx.draw_text(x, y + 1, '█   █')
            gfx.draw_text(x, y + 2, '█████')
            gfx.draw_text(x, y + 3, '█   █')
            gfx.draw_text(x, y + 4, '█████')
        }
        9 {
            gfx.draw_text(x, y + 0, '█████')
            gfx.draw_text(x, y + 1, '█   █')
            gfx.draw_text(x, y + 2, '█████')
            gfx.draw_text(x, y + 3, '    █')
            gfx.draw_text(x, y + 4, '█████')
        }
        else {}
    }
}

fn (mut g Game) draw() {
    mut gfx := g.app.tui
    gfx.set_bg_color(white)
    // Border
    gfx.draw_empty_rect(1, 1, g.app.width, g.app.height)
    // Center line
    gfx.draw_dashed_line(int(f32(g.app.width) * 0.5), 0, int(f32(g.app.width) * 0.5),
        int(g.app.height))
    border := 1
    mut y, mut x := 0, 0
    for p in g.players {
        x = int(p.pos.x)
        y = int(p.pos.y)
        gfx.reset_bg_color()
        gfx.set_color(white)
        if x < f32(g.app.width) * 0.5 {
            g.draw_big_digit(f32(g.app.width) * 0.25, 3, p.score)
        } else {
            g.draw_big_digit(f32(g.app.width) * 0.75, 3, p.score)
        }
        gfx.reset_color()
        gfx.set_bg_color(white)
        // Racket
        gfx.draw_line(x, y + border, x, y + p.racket_size)
    }
    // Ball
    gfx.draw_point(int(g.ball.pos.x), int(g.ball.pos.y))
    // gfx.draw_text(22,2,'${g.ball.pos}')
    gfx.reset_bg_color()
}

fn (mut g Game) free() {
    g.players.clear()
}

// TODO: Remove these wrapper functions when we can assign methods as callbacks
fn init(mut app App) {
    app.init()
}

fn frame(mut app App) {
    app.frame()
}

fn cleanup(mut app App) {
    unsafe {
        app.free()
    }
}

fn fail(error string) {
    eprintln(error)
}

fn event(e &ui.Event, mut app App) {
    app.event(e)
}

type InitFn = fn (voidptr)

type EventFn = fn (&ui.Event, voidptr)

type FrameFn = fn (voidptr)

type CleanupFn = fn (voidptr)

fn main() {
    mut app := &App{}
    app.tui = ui.init(
        user_data:      app
        init_fn:        InitFn(init)
        frame_fn:       FrameFn(frame)
        cleanup_fn:     CleanupFn(cleanup)
        event_fn:       EventFn(event)
        fail_fn:        fail
        capture_events: true
        hide_cursor:    true
        frame_rate:     60
    )
    app.tui.run()!
}