#include "user.h"
#include "renderer.h"
#include "font.h"
#include "texture.h"
#include "draw.h"
#include "intrinsics.h"
#include "app.h"
#include "game.h"
#include "asset_cache.h"
#include "string.h"
#include "scratch.h"
#include "math.h"
#include "console.h"
#include "sys.h"
#include "world.h"
#include "entity.h"

/* FIXME: remove this (testing) */
#include "sound.h"
#include "mixer.h"

struct view {
    f32 px_per_unit;

    struct v2 center;
    f32 zoom;
    f32 rot;
};

struct bind_state {
    b32 is_held;       /* Is this bind held down this frame */
    u32 num_presses;   /* How many times was this bind pressed since last frame */
    u32 num_releases;  /* How many times was this bind released since last frame */
};

struct blend_tick {
    struct blend_tick *next;
    struct blend_tick *prev;
    struct world world;
};

GLOBAL struct {
    b32 shutdown;
    struct sys_thread user_thread;

    struct arena arena;

    struct sys_window *window;
    struct renderer_canvas *world_canvas;
    struct renderer_canvas *screen_canvas;
    struct view world_view;

    struct blend_tick *head_free_blend_tick;
    struct blend_tick *head_blend_tick;
    struct world world;

    struct bind_state bind_states[USER_BIND_KIND_COUNT];

    b32 debug_camera;
    b32 debug_camera_panning;
    struct v2 debug_camera_pan_start;

    b32 debug_draw;

    /* User thread input */
    struct sys_mutex sys_events_mutex;
    struct arena sys_events_arena;

    /* Per-frame */
    f64 time;
    f64 dt;
    struct v2 screen_size;
    struct v2 screen_center;
    struct v2 screen_mouse;
    struct v2 screen_mouse_delta;
    struct v2 world_mouse;
    struct v2 last_focus_screen_pos;
} L = { 0 }, DEBUG_LVAR(L_user);

/* ========================== *
 * Bind state
 * ========================== */

/* TODO: Remove this */

GLOBAL READONLY enum user_bind_kind g_binds[SYS_BTN_COUNT] = {
    [SYS_BTN_W] = USER_BIND_KIND_MOVE_UP,
    [SYS_BTN_S] = USER_BIND_KIND_MOVE_DOWN,
    [SYS_BTN_A] = USER_BIND_KIND_MOVE_LEFT,
    [SYS_BTN_D] = USER_BIND_KIND_MOVE_RIGHT,

    /* Testing */

    [SYS_BTN_C]             = USER_BIND_KIND_DEBUG_CLEAR,
    [SYS_BTN_F6]            = USER_BIND_KIND_DEBUG_DRAW,
    [SYS_BTN_F7]            = USER_BIND_KIND_DEBUG_CAMERA,
    [SYS_BTN_MWHEELUP]      = USER_BIND_KIND_ZOOM_IN,
    [SYS_BTN_MWHEELDOWN]    = USER_BIND_KIND_ZOOM_OUT,
    [SYS_BTN_M3]            = USER_BIND_KIND_PAN
};

/* ========================== *
 * Window -> user communication
 * ========================== */

INTERNAL struct sys_event_array pop_sys_events(struct arena *arena)
{
    struct sys_event_array array = { 0 };
    if (L.sys_events_arena.pos > 0) {
        sys_mutex_lock(&L.sys_events_mutex);
        {
            struct buffer events_buff = arena_to_buffer(&L.sys_events_arena);
            arena_align(arena, ALIGNOF(struct sys_event));
            array.events = (struct sys_event *)arena_push_array(arena, u8, events_buff.size);
            array.count = events_buff.size / sizeof(struct sys_event);
            MEMCPY(array.events, events_buff.data, events_buff.size);
            arena_reset(&L.sys_events_arena);
        }
        sys_mutex_unlock(&L.sys_events_mutex);
    }
    return array;
}

INTERNAL void window_event_callback(struct sys_event event)
{
    sys_mutex_lock(&L.sys_events_mutex);
    {
        *arena_push(&L.sys_events_arena, struct sys_event) = event;
    }
    sys_mutex_unlock(&L.sys_events_mutex);
}

/* ========================== *
 * Game -> user communication
 * ========================== */

INTERNAL struct blend_tick *blend_tick_alloc(void)
{
    struct blend_tick *bt = NULL;
    if (L.head_free_blend_tick) {
        bt = L.head_free_blend_tick;
        L.head_free_blend_tick = bt->next;
        *bt = (struct blend_tick) {
            .world = bt->world
        };
    } else {
        bt = arena_push_zero(&L.arena, struct blend_tick);
        world_alloc(&bt->world);
    }
    if (L.head_blend_tick) {
        bt->next = L.head_blend_tick;
        L.head_blend_tick->prev = bt;
    }
    L.head_blend_tick = bt;
    return bt;
}

INTERNAL void blend_tick_release(struct blend_tick *bt)
{
    struct blend_tick *next = bt->next;
    struct blend_tick *prev = bt->prev;

    /* Remove from list */
    if (next) {
        next->prev = prev;
    }
    if (prev) {
        prev->next = next;
    }
    if (bt == L.head_blend_tick) {
        L.head_blend_tick = next;
    }

    /* Add to free list */
    bt->next = L.head_free_blend_tick;
    bt->prev = NULL;
    L.head_free_blend_tick = bt;
}

struct interp_ticks {
    struct world *from_tick;
    struct world *to_tick;
};

INTERNAL struct interp_ticks pull_ticks(f64 blend_time)
{
    __prof;

    /* Find newest stored tick */
    struct world *newest_tick = NULL;
    for (struct blend_tick *bt = L.head_blend_tick; bt; bt = bt->next) {
        if (!newest_tick || bt->world.tick_id > newest_tick->tick_id) {
            newest_tick = &bt->world;
        }
    }

    /* Pull new tick from game thread if necessary */
    if (!newest_tick || game_get_latest_tick_id() > newest_tick->tick_id) {
        struct blend_tick *latest_bt = blend_tick_alloc();
        newest_tick = &latest_bt->world;
        game_get_latest_tick(newest_tick);
    }

    /* Find oldest tick */
    struct world *oldest_tick = NULL;
    for (struct blend_tick *bt = L.head_blend_tick; bt; bt = bt->next) {
        if (!oldest_tick || bt->world.tick_id < oldest_tick->tick_id) {
            oldest_tick = &bt->world;
        }
    }

    /* Find closest ticks to blend time */
    struct world *from_tick = oldest_tick;
    struct world *to_tick = newest_tick;
    for (struct blend_tick *bt = L.head_blend_tick; bt; bt = bt->next) {
        f64 bt_time = sys_timestamp_seconds(bt->world.tick_ts);

        if (bt_time < blend_time && bt_time > sys_timestamp_seconds(from_tick->tick_ts)) {
            from_tick = &bt->world;
        }

        if (bt_time > blend_time && bt_time < sys_timestamp_seconds(to_tick->tick_ts)) {
            to_tick = &bt->world;
        }
    }

    /* Free any unused old ticks */
    {
        struct temp_arena scratch = scratch_begin_no_conflict();
        struct blend_tick **bts_to_free = arena_dry_push(scratch.arena, struct blend_tick *);
        u64 bts_to_free_count = 0;

        for (struct blend_tick *bt = L.head_blend_tick; bt; bt = bt->next) {
            f64 bt_time = sys_timestamp_seconds(bt->world.tick_ts);
            if (bt_time < sys_timestamp_seconds(from_tick->tick_ts)) {
                *arena_push(scratch.arena, struct blend_tick *) = bt;
                ++bts_to_free_count;
            }
        }

        for (u64 i = 0; i < bts_to_free_count; ++i) {
            blend_tick_release(bts_to_free[i]);
        }

        scratch_end(scratch);
    }

    return (struct interp_ticks) {
        .from_tick = from_tick,
        .to_tick = to_tick
    };
}

/* ========================== *
 * User -> game communication
 * ========================== */

struct game_cmd_node {
    struct game_cmd cmd;
    struct game_cmd_node *next;
};

struct game_cmd_list {
    struct arena *arena;
    struct game_cmd_node *first;
    struct game_cmd_node *last;
};

INTERNAL void queue_game_cmd(struct game_cmd_list *list, struct game_cmd cmd)
{
    struct game_cmd_node *node = arena_push_zero(list->arena, struct game_cmd_node);
    node->cmd = cmd;
    if (list->first) {
        list->last->next = node;
    } else {
        list->first = node;
    }
    list->last = node;
}

INTERNAL void pubilsh_game_cmds(struct game_cmd_list *list)
{
    struct temp_arena scratch = scratch_begin(list->arena);

    /* Construct array */
    struct game_cmd_array array = { .cmds = arena_dry_push(scratch.arena, struct game_cmd) };
    for (struct game_cmd_node *node = list->first; node; node = node->next) {
        struct game_cmd *cmd = arena_push(scratch.arena, struct game_cmd);
        *cmd = node->cmd;
        ++array.count;
    }

    /* Push array to game thread */
    if (array.count > 0) {
        game_push_cmds(array);
    }

    scratch_end(scratch);
}

/* ========================== *
 * View
 * ========================== */

INTERNAL struct xform view_get_xform(struct view view)
{
    f32 scale = view.zoom * view.px_per_unit;
    struct trs trs = TRS(
        .t = v2_sub(L.screen_center, view.center),
        .r = view.rot,
        .s = V2(scale, scale)
    );

    struct v2 pivot = view.center;
    struct xform res = XFORM_IDENT;
    res = xform_translate(res, pivot);
    res = xform_trs_pivot_rs(res, trs, pivot);

    return res;
}

INTERNAL struct v2 view_xform_v2(struct view view, struct v2 p)
{
    struct xform mtx = view_get_xform(view);
    return xform_mul_v2(mtx, p);
}

INTERNAL struct v2 view_xform_basis_v2(struct view view, struct v2 p)
{
    struct xform mtx = view_get_xform(view);
    return xform_basis_mul_v2(mtx, p);
}

INTERNAL struct v2 view_inverse_xform_v2(struct view view, struct v2 p)
{
    return xform_invert_mul_v2(view_get_xform(view), p);
}

INTERNAL struct v2 view_inverse_xform_basis_v2(struct view view, struct v2 p)
{
    return xform_basis_invert_mul_v2(view_get_xform(view), p);
}

/* ========================== *
 * Update
 * ========================== */

/* TODO: remove this (testing) */
INTERNAL void debug_draw_xform(struct xform xf)
{
    f32 thickness = 2.f / PIXELS_PER_UNIT / L.world_view.zoom;
    f32 arrowhead_len = 15.f / PIXELS_PER_UNIT / L.world_view.zoom;
    u32 color   = RGBA_F(0, 1, 1, 0.3);
    u32 color_x = RGBA_F(1, 0, 0, 0.3);
    u32 color_y = RGBA_F(0, 1, 0, 0.3);

    struct v2 pos   = xf.og;
    struct v2 x_ray = xform_get_right(xf);
    struct v2 y_ray = xform_get_up(xf);

    struct quad quad = quad_from_rect(RECT(0, 0, 1, -1));
    quad = quad_mul_xform(quad_scale(quad, 0.075), xf);

    draw_solid_arrow_ray(L.world_canvas, pos, x_ray, thickness, arrowhead_len, color_x);
    draw_solid_arrow_ray(L.world_canvas, pos, y_ray, thickness, arrowhead_len, color_y);
    draw_solid_quad(L.world_canvas, quad, color);
}

/* TODO: remove this (testing) */
INTERNAL void debug_draw_movement(struct entity *ent)
{
    f32 thickness = 2.f / PIXELS_PER_UNIT / L.world_view.zoom;
    f32 arrow_len = 15.f / PIXELS_PER_UNIT / L.world_view.zoom;

    u32 color_vel = RGBA_F(1, 0.5, 0, 1);
    u32 color_acc = RGBA_F(1, 1, 0.5, 1);

    struct v2 pos = ent->world_xform.og;
    struct v2 vel_ray = ent->velocity;
    struct v2 acc_ray = ent->acceleration;

    draw_solid_arrow_ray(L.world_canvas, pos, vel_ray, thickness, arrow_len, color_vel);
    draw_solid_arrow_ray(L.world_canvas, pos, acc_ray, thickness, arrow_len, color_acc);
}

INTERNAL void user_update(void)
{
    struct temp_arena scratch = scratch_begin_no_conflict();
    struct game_cmd_list cmd_list = {
        .arena = scratch.arena
    };

    /* Get time */
    f64 cur_time = sys_timestamp_seconds(sys_timestamp());
    L.dt = max_f64(0.0, cur_time - L.time);
    L.time += L.dt;

    /* Get screen dimensions */
    L.screen_size = sys_window_get_size(L.window);
    /* Make screen_size an even number */
    L.screen_size = V2(math_round(L.screen_size.x), math_round(L.screen_size.y));
    L.screen_size = V2(
        math_round(L.screen_size.x) % 2 == 0 ? L.screen_size.x : L.screen_size.x + 1,
        math_round(L.screen_size.y) % 2 == 0 ? L.screen_size.y : L.screen_size.y + 1
    );
    L.screen_center = v2_mul(L.screen_size, 0.5);

    /* ========================== *
     * Produce interpolated tick
     * ========================== */

    b32 tick_is_first_frame = false;
    {
        __profscope(produce_interpolated_tick);

        f64 blend_time_offset = (1.0 / GAME_FPS) * USER_INTERP_OFFSET_TICK_RATIO;
        f64 blend_time = L.time > blend_time_offset ? L.time - blend_time_offset : 0;

        /* Pull ticks */
        struct interp_ticks interp_ticks = pull_ticks(blend_time);
        struct world *t0 = interp_ticks.from_tick;
        struct world *t1 = interp_ticks.to_tick;

        tick_is_first_frame = (t0->tick_id == 0 || t1->tick_id == 0);

        f32 tick_blend = 0;
        {
            f64 t0_time = sys_timestamp_seconds(t0->tick_ts);
            f64 t1_time = sys_timestamp_seconds(t1->tick_ts);
            if (t1_time > t0_time) {
                tick_blend = (f32)((blend_time - t0_time) / (t1_time - t0_time));
            }
            tick_blend = clamp_f32(tick_blend, 0.0f, 1.0f);
        }

        world_copy_replace(&L.world, t1);
#if 1
        /* Blend time */
        L.world.time = math_lerp_f64(t0->time, t1->time, (f64)tick_blend);

        /* Blend entities */
        struct entity_array t0_entities =  entity_store_as_array(&t0->entity_store);
        struct entity_array t1_entities = entity_store_as_array(&t1->entity_store);
        struct entity_array world_entities = entity_store_as_array(&L.world.entity_store);

        u64 num_entities = min_u64(t0_entities.count, t1_entities.count);
        for (u64 i = 0; i < num_entities; ++i) {
            struct entity *e0 = &t0_entities.entities[i];
            struct entity *e1 = &t1_entities.entities[i];
            struct entity *e = &world_entities.entities[i];
            if (e0->handle.gen == e1->handle.gen && e0->continuity_gen == e1->continuity_gen) {
                e->rel_xform = xform_lerp(e0->rel_xform, e1->rel_xform, tick_blend);
                e->world_xform = xform_lerp(e0->world_xform, e1->world_xform, tick_blend);

                e->acceleration = v2_lerp(e0->acceleration, e1->acceleration, tick_blend);
                e->velocity = v2_lerp(e0->velocity, e1->velocity, tick_blend);
                e->player_acceleration = math_lerp_f32(e0->player_acceleration, e1->player_acceleration, tick_blend);
                e->player_focus_dir = v2_lerp(e0->player_focus_dir, e1->player_focus_dir, tick_blend);

                e->sprite_xform = xform_lerp(e0->sprite_xform, e1->sprite_xform, tick_blend);
                e->animation_time_in_frame = math_lerp_f64(e0->animation_time_in_frame, e1->animation_time_in_frame, (f64)tick_blend);

                e->camera_zoom = math_lerp_f32(e0->camera_zoom, e1->camera_zoom, tick_blend);
            }
        }
#else
        (UNUSED)tick_blend;
#endif
    }

    struct entity_array entities_array = entity_store_as_array(&L.world.entity_store);

    /* ========================== *
     * Read sys events
     * ========================== */

    struct sys_event_array events = pop_sys_events(scratch.arena);

    /* Reset bind states "was_pressed" */
    for (u32 i = 0; i < ARRAY_COUNT(L.bind_states); ++i) {
        L.bind_states[i] = (struct bind_state) {
            .is_held = L.bind_states[i].is_held
        };
    }

    L.screen_mouse_delta = V2(0, 0);

    for (u64 entity_index = 0; entity_index < events.count; ++entity_index) {
        struct sys_event *event = &events.events[entity_index];

        /* Send event to console. Skip if consumed. */
        if (console_process_event(*event)) {
            continue;
        }

        if (event->kind == SYS_EVENT_KIND_QUIT) {
            app_quit();
        }

        if (event->kind == SYS_EVENT_KIND_BUTTON_UP) {
#if DEVELOPER
            /* Escape quit */
            if (event->button == SYS_BTN_ESC) {
                app_quit();
            }
#endif
        }

        /* Text */
        if (event->kind == SYS_EVENT_KIND_TEXT) {
            /* TODO: remove this (sound test) */
            {
                //u32 flags = SOUND_FLAG_STEREO;
                u32 flags = 0;
                struct sound *sound = sound_load(STR("res/sounds/test.mp3"), flags);
                if (sound) {
                    mixer_play_ex(sound, MIXER_DESC(.volume = 1.0, .speed = 1.0));
                }
            }
        }

        /* Update mouse pos */
        if (event->kind == SYS_EVENT_KIND_MOUSE_MOVE) {
            L.screen_mouse = event->mouse_position;
        }

        /* Update mouse delta */
        if (event->kind == SYS_EVENT_KIND_RAW_MOUSE_MOVE) {
            L.screen_mouse_delta = v2_add(L.screen_mouse_delta, event->raw_mouse_delta);
        }

        /* Update bind states */
        if ((event->kind == SYS_EVENT_KIND_BUTTON_DOWN || event->kind == SYS_EVENT_KIND_BUTTON_UP) && !event->is_repeat) {
            enum sys_btn button = event->button;
            button = button >= SYS_BTN_COUNT ? SYS_BTN_NONE : button;
            enum user_bind_kind bind = g_binds[button];
            if (bind) {
                b32 pressed = event->kind == SYS_EVENT_KIND_BUTTON_DOWN;
                L.bind_states[bind].is_held = pressed;
                if (pressed) {
                    ++L.bind_states[bind].num_presses;
                } else {
                    ++L.bind_states[bind].num_releases;
                }
            }
        }
    }

    /* ========================== *
     * Debug commands
     * ========================== */

    /* Test clear world */
    {
        struct bind_state state = L.bind_states[USER_BIND_KIND_DEBUG_CLEAR];
        if (state.num_presses || state.is_held) {
            queue_game_cmd(&cmd_list, (struct game_cmd) {
                .kind = GAME_CMD_KIND_CLEAR_ALL
            });
        }
    }

    /* ========================== *
     * Update view from debug camera
     * ========================== */

    if (L.bind_states[USER_BIND_KIND_DEBUG_DRAW].num_presses > 0) {
        L.debug_draw = !L.debug_draw;
    }

    if (L.bind_states[USER_BIND_KIND_DEBUG_CAMERA].num_presses > 0) {
        if (!L.debug_camera) {
            /* Move cursor to last crosshair pos */
            sys_window_cursor_set_pos(L.window, L.last_focus_screen_pos);
        }
        L.debug_camera = !L.debug_camera;
    }

    if (L.debug_camera) {
        sys_window_cursor_show(L.window);
        sys_window_cursor_disable_keep_in_window(L.window);

        /* Pan view */
        if (L.bind_states[USER_BIND_KIND_PAN].is_held) {
            if (!L.debug_camera_panning) {
                L.debug_camera_pan_start = view_inverse_xform_v2(L.world_view, L.screen_mouse);
            }
            L.debug_camera_panning = true;
            struct v2 offset = v2_sub(L.debug_camera_pan_start, view_inverse_xform_v2(L.world_view, L.screen_mouse));
            L.world_view.center = v2_add(L.world_view.center, offset);
            L.debug_camera_pan_start = view_inverse_xform_v2(L.world_view, L.screen_mouse);
        } else {
            L.debug_camera_panning = false;
        }

        /* Zoom view */
        i32 input_zooms = L.bind_states[USER_BIND_KIND_ZOOM_IN].num_presses - L.bind_states[USER_BIND_KIND_ZOOM_OUT].num_presses;
        if (input_zooms != 0) {
            i32 dir = input_zooms >= 0 ? 1 : -1;
            u32 zooms_abs = input_zooms >= 0 ? input_zooms : -input_zooms;

            /* Zoom camera/view */
            f32 zoom_rate = 2;
            f32 zoom_min = 1.f / 128.f;
            f32 zoom_max = 1.f * 128.f;
            f32 new_zoom = L.world_view.zoom;
            for (u32 i = 0; i < zooms_abs; ++i) {
                if (dir > 0) {
                    new_zoom *= zoom_rate;
                } else {
                    new_zoom *= 1.0f / zoom_rate;
                }
                new_zoom = clamp_f32(new_zoom, zoom_min, zoom_max);
            }

            struct v2 old_mouse = view_inverse_xform_v2(L.world_view, L.screen_mouse);
            L.world_view.zoom = new_zoom;
            struct v2 new_mouse = view_inverse_xform_v2(L.world_view, L.screen_mouse);

            /* Offset view to zoom in on mouse */
            struct v2 offset = v2_sub(old_mouse, new_mouse);
            L.world_view.center = v2_add(L.world_view.center, offset);
        }
    } else {
        /* Keep cursor invisible and in screen */
        sys_window_cursor_hide(L.window);
        sys_window_cursor_enable_keep_in_window(L.window);

        enum entity_prop props[] = { ENTITY_PROP_CAMERA, ENTITY_PROP_CAMERA_ACTIVE };
        struct entity_prop_array props_array = {
            .props = props,
            .count = ARRAY_COUNT(props)
        };
        struct entity *ent = entity_find_first_match_all(&L.world.entity_store, props_array);

        struct v2 center = ent->world_xform.og;
        f32 rot = xform_get_rotation(ent->world_xform);
        f32 zoom = ent->camera_zoom;
        zoom = zoom > 0 ? zoom : 1;
        L.world_view.center = center;
        L.world_view.rot = rot;
        L.world_view.zoom = zoom;
        L.world_mouse = view_inverse_xform_v2(L.world_view, L.screen_mouse);
    }

    /* ========================== *
     * Construct movement input
     * ========================== */

    /* Movement */
    {
        struct v2 player_move_dir = { 0 };
        for (enum user_bind_kind bind = 0; bind < (i32)ARRAY_COUNT(L.bind_states); ++bind) {
            struct bind_state state = L.bind_states[bind];

            if (!state.is_held && state.num_presses <= 0) {
                continue;
            }

            switch (bind) {
                /* Movement */
                case USER_BIND_KIND_MOVE_UP: {
                    player_move_dir.y -= 1;
                } break;

                case USER_BIND_KIND_MOVE_DOWN: {
                    player_move_dir.y += 1;
                } break;

                case USER_BIND_KIND_MOVE_LEFT: {
                    player_move_dir.x -= 1;
                } break;

                case USER_BIND_KIND_MOVE_RIGHT: {
                    player_move_dir.x += 1;
                } break;

                default: break;
            }
        }

        player_move_dir = view_inverse_xform_basis_v2(L.world_view, player_move_dir);  /* Make move dir relative to world view */
        player_move_dir = v2_norm(player_move_dir);

        struct game_cmd cmd = (struct game_cmd) {
            .kind = GAME_CMD_KIND_PLAYER_MOVE,
            .move_dir = player_move_dir
        };
        if (!L.debug_camera) {
            struct v2 focus_move_dir = view_inverse_xform_basis_v2(L.world_view, L.screen_mouse_delta);  /* Make focus relative to world view direction */
            focus_move_dir = v2_mul(focus_move_dir, MOUSE_SENSITIVITY);
            cmd.focus_move_dir = focus_move_dir;
        }
        queue_game_cmd(&cmd_list, cmd);
    }

    /* ========================== *
     * Draw test grid
     * ========================== */

    {
        f32 thickness = 3.f / PIXELS_PER_UNIT / L.world_view.zoom;
        u32 color = RGBA(0x3f, 0x3f, 0x3f, 0xFF);
        u32 x_color = RGBA(0x3f, 0, 0, 0xFF);
        u32 y_color = RGBA(0, 0x3f, 0, 0xFF);

        i64 startx = -10;
        i64 starty = -10;
        i64 rows = 20;
        i64 cols = 20;

        /* Draw column lines */
        struct v2 col_ray = V2(0, rows);
        for (i64 col = starty; col <= (starty + cols); ++col) {
            u32 line_color = color;
            if (col == 0) {
                line_color = y_color;
            }

            struct v2 pos = V2(col, starty);
            draw_solid_ray(L.world_canvas, pos, col_ray, thickness, line_color);
        }

        struct v2 row_ray = V2(cols, 0);
        for (i64 row = startx; row <= (startx + rows); ++row) {
            u32 line_color = color;
            if (row == 0) {
                line_color = x_color;
            }
            struct v2 pos = V2(startx, row);
            draw_solid_ray(L.world_canvas, pos, row_ray, thickness, line_color);
        }
    }

    /* ---------------------------------------------------------------------- */
    /* ---------------------------------------------------------------------- */

    /* ========================== *
     * Iterate entities
     * ========================== */

    /* Iterate entities */
    for (u64 entity_index = 0; entity_index < entities_array.count; ++entity_index) {
        __profscope(user_entity_iter);

        struct entity *ent = &entities_array.entities[entity_index];
        if (!ent->valid) continue;

        b32 is_camera = entity_has_prop(ent, ENTITY_PROP_CAMERA);

        /* Draw sprite */
        if (ent->sprite_name.len > 0) {
            struct string tex_name = ent->sprite_name;

            /* Draw texture */

            struct texture *texture = texture_load_async(tex_name);
            if (texture) {
                struct xform xf = xform_mul(ent->world_xform, ent->sprite_xform);
                struct quad quad = quad_mul_xform(QUAD_UNIT_SQUARE_CENTERED, xf);

                u32 tint = ent->sprite_tint;
                struct draw_texture_params params = DRAW_TEXTURE_PARAMS(.texture = texture, .tint = tint);

                struct sheet *sheet = sheet_load(ent->sprite_name);
                if (sheet) {
                    struct sheet_tag tag = sheet_get_tag(sheet, ent->sprite_tag_name);

                    u64 frame_index = tag.start + ent->animation_frame;
                    struct sheet_frame frame = sheet_get_frame(sheet, frame_index);
                    if (entity_has_prop(ent, ENTITY_PROP_ANIMATING)) {
                        f64 time_in_frame = ent->animation_time_in_frame;
                        while (time_in_frame > frame.duration) {
                            time_in_frame -= frame.duration;
                            ++frame_index;
                            if (frame_index > tag.end) {
                                /* Loop animation */
                                frame_index = tag.start;
                            }
                            frame = sheet_get_frame(sheet, frame_index);
                        }
                    }

                    params.clip = frame.clip;
                }

                draw_texture_quad(L.world_canvas, params, quad);

#if 0
                if (L.debug_draw && !is_camera) {
                    /* Debug draw sprite quad */
                    {
                        f32 thickness = 2.f;
                        u32 color = RGBA_F(1, 1, 0, 0.25);
                        draw_solid_quad_line(L.world_canvas, quad, (thickness / PIXELS_PER_UNIT / L.world_view.zoom), color);
                    }

                    /* Debug draw sprite transform */
                    {
                        debug_draw_xform(xf);
                    }

                    /* Debug draw sprite pivot */
                    {
                        u32 color = RGBA_F(1, 0, 0, 1);
                        draw_solid_circle(L.world_canvas, ent->world_xform.og, 0.02, color, 20);
                    }
                }
#endif
            }
        }

        /* Draw crosshair */
        if (!L.debug_camera && entity_has_prop(ent, ENTITY_PROP_PLAYER_CONTROLLED)) {
            struct v2 focus_pos = v2_add(ent->world_xform.og, ent->player_focus_dir);
            struct v2 focus_pos_screen = view_xform_v2(L.world_view, focus_pos);
            u32 tint = RGBA_F(1, 1, 1, 0.5);

            struct texture *t = texture_load_async(STR("res/graphics/crosshair.ase"));
            if (t) {
                struct xform xf = XFORM_TRS(.t = focus_pos_screen, .s = t->size);
                struct quad quad = quad_mul_xform(QUAD_UNIT_SQUARE_CENTERED, xf);
                draw_texture_quad(L.screen_canvas, DRAW_TEXTURE_PARAMS(.texture = t, .tint = tint), quad);
            }

            L.last_focus_screen_pos = focus_pos_screen;
        }

        /* Debug draw info */
        if (L.debug_draw && !is_camera) {
            struct temp_arena temp = arena_temp_begin(scratch.arena);

#if 0
            struct font *disp_font = font_load_async(STR("res/fonts/fixedsys.ttf"), 12.0f);
            if (disp_font) {
                struct xform xf = ent->world_xform;
                struct trs trs = trs_from_xform(xf);
                struct v2 velocity = ent->velocity;
                struct v2 acceleration = ent->acceleration;

                f32 offset = 1;
                struct v2 pos = v2_add(xf.og, v2_mul(V2(0, -1), offset));
                pos = view_xform_v2(L.world_view, pos);
                pos = v2_round(pos);

                struct string disp_name = ent->sprite_name;

                struct string fmt = STR(
                    "sprite name: \"%F\"\n"
                    "pos: (%F, %F)\n"
                    "scale: (%F, %F)\n"
                    "rot: %F\n"
                    "velocity: (%F, %F)\n"
                    "acceleration: (%F, %F)\n"
                );
                struct string text = string_format(temp.arena, fmt,
                                                   FMT_STR(disp_name),
                                                   FMT_FLOAT((f64)trs.t.x), FMT_FLOAT((f64)trs.t.y),
                                                   FMT_FLOAT((f64)trs.s.x), FMT_FLOAT((f64)trs.s.y),
                                                   FMT_FLOAT((f64)trs.r),
                                                   FMT_FLOAT((f64)velocity.x), FMT_FLOAT((f64)velocity.y),
                                                   FMT_FLOAT((f64)acceleration.x), FMT_FLOAT((f64)acceleration.y)
                                                   );


                draw_text(L.screen_canvas, disp_font, pos, text);
            }
#endif

            debug_draw_xform(ent->world_xform);
            debug_draw_movement(ent);

            /* Draw hierarchy */
            struct entity *parent = entity_from_handle(&L.world.entity_store, ent->parent);
            if (parent->valid) {
                u32 color = RGBA_F(0.6, 0.6, 1, 0.75);
                f32 thickness = 5;
                f32 arrow_height = 15;

                struct v2 start = view_xform_v2(L.world_view, ent->world_xform.og);
                struct v2 end = view_xform_v2(L.world_view, parent->world_xform.og);
                draw_solid_arrow_line(L.screen_canvas, start, end, thickness, arrow_height, color);
            }

            /* Draw focus */
            if (entity_has_prop(ent, ENTITY_PROP_PLAYER_CONTROLLED)) {
                u32 color = RGBA_F(0.75, 0, 0.75, 0.5);
                f32 thickness = 3;
                f32 arrow_height = 10;
                struct v2 pos = view_xform_v2(L.world_view, ent->world_xform.og);
                struct v2 focus_ray = view_xform_basis_v2(L.world_view, ent->player_focus_dir);
                draw_solid_arrow_ray(L.screen_canvas, pos, focus_ray, thickness, arrow_height, color);
            }

            arena_temp_end(temp);
        }
    }

    /* ---------------------------------------------------------------------- */
    /* ---------------------------------------------------------------------- */

    /* Update listener using world view */
    mixer_set_listener(L.world_view.center, V2(-math_sin(L.world_view.rot), -math_cos(L.world_view.rot)));

    /* Debug draw info */
    if (L.debug_draw) {
        struct temp_arena temp = arena_temp_begin(scratch.arena);

        f32 spacing = 20;
        struct v2 pos = V2(10, 8);
        struct font *font = font_load(STR("res/fonts/fixedsys.ttf"), 12.0f);

        draw_text(L.screen_canvas, font, pos, string_format(temp.arena, STR("time: %F"), FMT_FLOAT((f64)L.time)));
        pos.y += spacing;

        draw_text(L.screen_canvas, font, pos, string_format(temp.arena, STR("screen_size: (%F, %F)"), FMT_FLOAT((f64)L.screen_size.x), FMT_FLOAT((f64)L.screen_size.y)));
        pos.y += spacing;

        draw_text(L.screen_canvas, font, pos, string_format(temp.arena, STR("screen_center: (%F, %F)"), FMT_FLOAT((f64)L.screen_center.x), FMT_FLOAT((f64)L.screen_center.y)));
        pos.y += spacing;

        draw_text(L.screen_canvas, font, pos, string_format(temp.arena, STR("screen_mouse: (%F, %F)"), FMT_FLOAT((f64)L.screen_mouse.x), FMT_FLOAT((f64)L.screen_mouse.y)));
        pos.y += spacing;

        draw_text(L.screen_canvas, font, pos, string_format(temp.arena, STR("world_view.center: (%F, %F)"), FMT_FLOAT((f64)L.world_view.center.x), FMT_FLOAT((f64)L.world_view.center.y)));
        pos.y += spacing;

        draw_text(L.screen_canvas, font, pos, string_format(temp.arena, STR("world_view.rot: %F"), FMT_FLOAT((f64)L.world_view.rot)));
        pos.y += spacing;

        draw_text(L.screen_canvas, font, pos, string_format(temp.arena, STR("world_view.zoom: %F"), FMT_FLOAT((f64)L.world_view.zoom)));
        pos.y += spacing;

        draw_text(L.screen_canvas, font, pos, string_format(temp.arena, STR("world_mouse: (%F, %F)"), FMT_FLOAT((f64)L.world_mouse.x), FMT_FLOAT((f64)L.world_mouse.y)));
        pos.y += spacing;

        draw_text(L.screen_canvas, font, pos, string_format(temp.arena, STR("debug_camera: %F"), FMT_STR(L.debug_camera ? STR("true") : STR("false"))));
        pos.y += spacing;

        arena_temp_end(temp);
    }

    /* Push game cmds */
    pubilsh_game_cmds(&cmd_list);

    /* ========================== *
     * Present
     * ========================== */

    /* Send canvases to GPU */
    renderer_canvas_send_to_gpu(L.world_canvas);
    renderer_canvas_send_to_gpu(L.screen_canvas);

    /* Set canvas views before presenting */
    renderer_canvas_set_view(L.world_canvas, view_get_xform(L.world_view));
    renderer_canvas_set_view(L.screen_canvas, view_get_xform((struct view) {.px_per_unit = 1, .center = L.screen_center, .rot = 0, .zoom = 1}));

    /* Present */
    i32 vsync = VSYNC_ENABLED;

    struct renderer_canvas **canvases = arena_dry_push(scratch.arena, struct renderer_canvas *);
    u64 canvases_count = 0;
    {
        /* Only render world if not on first frame */
        if (!tick_is_first_frame) {
            *arena_push(scratch.arena, struct renderer_canvas *) = L.world_canvas;
            ++canvases_count;
        }

        *arena_push(scratch.arena, struct renderer_canvas *) = L.screen_canvas;
        ++canvases_count;
    }

    renderer_canvas_present(canvases, canvases_count, L.screen_size.x, L.screen_size.y, vsync);

    scratch_end(scratch);
}

/* ========================== *
 * Startup
 * ========================== */

INTERNAL void user_thread_entry_point(void *arg)
{
    (UNUSED)arg;

    sys_timestamp_t last_frame_ts = 0;
    f64 target_dt = USER_FRAME_LIMIT > (0) ? (1.0 / USER_FRAME_LIMIT) : 0;

    while (!L.shutdown) {
        __profscope(user_update_w_sleep);
        sleep_frame(last_frame_ts, target_dt);
        last_frame_ts = sys_timestamp();
        user_update();
    }
}

void user_startup(struct sys_window *window)
{
    L.arena = arena_alloc(GIGABYTE(64));

    L.sys_events_mutex = sys_mutex_alloc();
    L.sys_events_arena = arena_alloc(GIGABYTE(64));

    world_alloc(&L.world);

    L.world_canvas = renderer_canvas_alloc();
    L.world_view = (struct view) {
        .px_per_unit = PIXELS_PER_UNIT,

        .center = V2(0, 0),
        .rot = 0,
        .zoom = 1
    };

    L.screen_canvas = renderer_canvas_alloc();

    L.window = window;
    sys_window_register_event_callback(L.window, &window_event_callback);

    L.user_thread = sys_thread_init(&user_thread_entry_point, NULL, STR("[P1] User thread"));
}

void user_shutdown(void)
{
    L.shutdown = true;
    sys_thread_join(&L.user_thread);
}