#include "game.h"
#include "sys.h"
#include "util.h"
#include "world.h"
#include "sprite.h"
#include "sound.h"
#include "mixer.h"
#include "math.h"
#include "scratch.h"
#include "atomic.h"
#include "app.h"
#include "log.h"
#include "phys.h"
#include "collider.h"

GLOBAL struct {
    struct atomic_i32 game_thread_shutdown;
    struct sys_thread game_thread;

    b32 paused;
    struct sprite_scope *sprite_frame_scope;

    /* For debugging */
    struct v2 user_cursor;

    /* TODO: Remove this (testing) */
    b32 extra_spawn;
    b32 should_reset_level;

    /* Game thread input */
    struct sys_mutex game_cmds_mutex;
    struct arena game_cmds_arena;
    struct entity *root;

    /* Bookkeeping structures */
    struct entity_lookup contact_lookup;
#if COLLIDER_DEBUG
    struct entity_lookup collision_debug_lookup;
#endif

    /* Ticks */
    struct sys_mutex prev_tick_mutex;
    struct atomic_u64 prev_tick_id;
    struct atomic_u64 prev_tick_continuity_gen;
    struct world prev_tick;
    struct world tick;
} G = ZI, DEBUG_ALIAS(G, G_game);

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

INTERNAL APP_EXIT_CALLBACK_FUNC_DEF(game_shutdown);
INTERNAL SYS_THREAD_ENTRY_POINT_FUNC_DEF(game_thread_entry_point, arg);
INTERNAL void reset_world(void);

struct game_startup_receipt game_startup(struct mixer_startup_receipt *mixer_sr,
                                         struct sprite_startup_receipt *sheet_sr,
                                         struct sound_startup_receipt *sound_sr,
                                         struct phys_startup_receipt *phys_sr)
{
    (UNUSED)mixer_sr;
    (UNUSED)sheet_sr;
    (UNUSED)sound_sr;
    (UNUSED)phys_sr;

    /* Initialize game cmd storage */
    G.game_cmds_mutex = sys_mutex_alloc();
    G.game_cmds_arena = arena_alloc(GIGABYTE(64));

    /* Initialize empty world */
    reset_world();

    /* Initialize prev tick */
    world_alloc(&G.prev_tick);
    /* FIXME: Make the world struct itself readonly as well */
    arena_set_readonly(&G.prev_tick.entity_store->arena);
    G.prev_tick_mutex = sys_mutex_alloc();

    G.game_thread = sys_thread_alloc(&game_thread_entry_point, NULL, STR("[P2] Game thread"));
    app_register_exit_callback(&game_shutdown);

    return (struct game_startup_receipt) { 0 };
}

INTERNAL APP_EXIT_CALLBACK_FUNC_DEF(game_shutdown)
{
    __prof;
    atomic_i32_eval_exchange(&G.game_thread_shutdown, true);
    sys_thread_wait_release(&G.game_thread);
}

/* ========================== *
 * Game cmd
 * ========================== */

INTERNAL void push_cmds(struct game_cmd_array cmd_array)
{
    struct sys_lock lock = sys_mutex_lock_e(&G.game_cmds_mutex);
    struct game_cmd *cmds = arena_push_array(&G.game_cmds_arena, struct game_cmd, cmd_array.count);
    MEMCPY(cmds, cmd_array.cmds, cmd_array.count * sizeof(*cmds));
    sys_mutex_unlock(&lock);
}

INTERNAL struct game_cmd_array pop_cmds(struct arena *arena)
{
    struct game_cmd_array array = ZI;
    if (G.game_cmds_arena.pos > 0) {
        struct sys_lock lock = sys_mutex_lock_e(&G.game_cmds_mutex);
        struct buffer game_cmds_buff = arena_to_buffer(&G.game_cmds_arena);
        arena_align(arena, alignof(struct game_cmd));
        array.cmds = (struct game_cmd *)arena_push_array(arena, u8, game_cmds_buff.size);
        array.count = game_cmds_buff.size / sizeof(struct game_cmd);
        MEMCPY(array.cmds, game_cmds_buff.data, game_cmds_buff.size);
        arena_reset(&G.game_cmds_arena);
        sys_mutex_unlock(&lock);
    }
    return array;
}

/* ========================== *
 * Reset
 * ========================== */

INTERNAL void reset_world(void)
{
    if (G.tick.entity_store) {
        /* Release world */
        world_release(&G.tick);
        /* Release bookkeeping */
#if COLLIDER_DEBUG
        entity_lookup_release(&G.collision_debug_lookup);
#endif
        entity_lookup_release(&G.contact_lookup);
    }

    /* Create bookkeeping */
    G.contact_lookup = entity_lookup_alloc(4096);
#if COLLIDER_DEBUG
    G.collision_debug_lookup = entity_lookup_alloc(4096);
#endif

    /* Re-create world */
    world_alloc(&G.tick);
    G.tick.continuity_gen = atomic_u64_eval(&G.prev_tick_continuity_gen) + 1;
    G.tick.timescale = GAME_TIMESCALE;
}

/* ========================== *
 * Test
 * ========================== */

/* TODO: Remove this */

INTERNAL void spawn_test_entities(void)
{
    struct entity *root = entity_from_handle(G.tick.entity_store, G.tick.entity_store->root);
    root->mass_unscaled = F32_INFINITY;
    root->inertia_unscaled = F32_INFINITY;

    /* Player */
    struct entity *player_ent = entity_nil();
    //if (!G.extra_spawn) {
    {

        struct entity *e = entity_alloc(root);

        struct v2 pos = V2(1, -1);

        //struct v2 size = V2(0.5, 0.5);
        //struct v2 size = V2(0.5, 0.25);
        struct v2 size = V2(1.0, 1.0);

        //f32 r = PI / 4;
        f32 r = 0;

        if (!G.extra_spawn) {
            entity_enable_prop(e, ENTITY_PROP_PLAYER_CONTROLLED);
            entity_enable_prop(e, ENTITY_PROP_TEST);
            e->sprite = sprite_tag_from_path(STR("res/graphics/tim.ase"));
            e->mass_unscaled = 10;
            e->inertia_unscaled = 5;
        } else {
            entity_enable_prop(e, ENTITY_PROP_TEST);
            e->sprite = sprite_tag_from_path(STR("res/graphics/tim.ase"));
            e->mass_unscaled = 10;
            e->inertia_unscaled = 5;
#if 0
            e->sprite = sprite_tag_from_path(STR("res/graphics/box.ase"));
            e->mass_unscaled = 100;
            e->inertia_unscaled = 100;
#endif
        }

        //e->sprite = sprite_tag_from_path(STR("res/graphics/box_rounded.ase"));
        //e->sprite_span_name = STR("idle.unarmed");
        //e->sprite_span_name = STR("idle.one_handed");
        e->sprite_span_name = STR("idle.two_handed");
        e->sprite_collider_slice = STR("shape");

        struct xform xf = XFORM_TRS(.t = pos, .r = r, .s = size);
        //xf.bx.y = -1.f;

        entity_set_xform(e, xf);

        e->linear_ground_friction = 250;
        e->angular_ground_friction = 200;

        //e->control_force = 500;
        e->control_force = 500;
        //e->control_force_max_speed = 4;
        e->control_torque = 1000;
        e->control_force_max_speed = 4;

        entity_enable_prop(e, ENTITY_PROP_PHYSICAL_DYNAMIC);

        player_ent = e;
    }

    /* Enemy */
    {
        struct entity *e = entity_alloc(root);

        struct v2 pos = V2(1, -2);
        f32 r = 0;
        struct v2 size = V2(1, 1);
        struct xform xf = XFORM_TRS(.t = pos, .r = r, .s = size);
        entity_set_xform(e, xf);

        e->sprite = sprite_tag_from_path(STR("res/graphics/tim.ase"));
        e->sprite_collider_slice = STR("shape");

        entity_enable_prop(e, ENTITY_PROP_PHYSICAL_DYNAMIC);
        e->mass_unscaled = 10;
        e->inertia_unscaled = 10;
        e->linear_ground_friction = 250;
        e->angular_ground_friction = 200;
    }


    /* Box */
#if 0
    {
        struct entity *e = entity_alloc(root);

        struct v2 pos = V2(1, -0.5);
        f32 r = 0;
        struct v2 size = V2(0.5, 0.25);
        struct xform xf = XFORM_TRS(.t = pos, .r = r, .s = size);
        entity_set_xform(e, xf);

        e->sprite = sprite_tag_from_path(STR("res/graphics/box.ase"));
        e->sprite_collider_slice = STR("shape");

        entity_enable_prop(e, ENTITY_PROP_PHYSICAL_DYNAMIC);
        e->mass_unscaled = 10;
        e->inertia_unscaled = 10;
        e->linear_ground_friction = 250;
        e->angular_ground_friction = 5;
    }
#endif

    /* Player weapon */
    if (player_ent->valid) {
        struct entity *e = entity_alloc(player_ent);
        e->sprite = sprite_tag_from_path(STR("res/graphics/gun.ase"));

        entity_enable_prop(e, ENTITY_PROP_ATTACHED);
        e->attach_slice = STR("attach.wep");

        entity_enable_prop(e, ENTITY_PROP_WEAPON);
        e->trigger_delay = 1.0f / 10.0f;

        player_ent->equipped = e->handle;
    }

    /* Camera */
    if (!G.extra_spawn && player_ent->valid) {
        struct entity *e = entity_alloc(root);
        entity_set_xform(e, XFORM_IDENT);

        entity_enable_prop(e, ENTITY_PROP_CAMERA);
        entity_enable_prop(e, ENTITY_PROP_CAMERA_ACTIVE);
        e->camera_follow = player_ent->handle;

        f32 width = (f32)DEFAULT_CAMERA_WIDTH;
        f32 height = (f32)DEFAULT_CAMERA_HEIGHT;
        e->camera_quad_xform = XFORM_TRS(.s = V2(width, height));
    }

    G.extra_spawn = true;
}

/* ========================== *
 * Release entities
 * ========================== */

INTERNAL void release_entities_with_prop(enum entity_prop prop)
{
    struct temp_arena scratch = scratch_begin_no_conflict();
    struct entity_store *store = G.tick.entity_store;

    /* TODO: Breadth first iteration to only release parent entities (since
     * child entities will be released along with parent anyway) */

    struct entity **ents_to_release = arena_dry_push(scratch.arena, struct entity *);
    u64 ents_to_release_count = 0;
    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!ent->valid) continue;

        if (entity_has_prop(ent, prop)) {
            *arena_push(scratch.arena, struct entity *) = ent;
            ++ents_to_release_count;
        }
    }

    for (u64 i = 0; i < ents_to_release_count; ++i) {
        struct entity *ent = ents_to_release[i];
        if (ent->valid) {
            /* Release */
            entity_release(store, ent);
        }
    }

    scratch_end(scratch);
}

/* ========================== *
 * Respond to physics collisions
 * ========================== */

INTERNAL PHYS_COLLISION_CALLBACK_FUNC_DEF(on_collision, array)
{
    struct entity_store *store = G.tick.entity_store;
    struct entity *root = entity_from_handle(store, store->root);

    for (u64 i = 0; i < array.count; ++i) {
        struct phys_collision_data *data = &array.a[i];

        struct phys_contact_constraint *constraint = data->constraint;
        struct entity *e0 = entity_from_handle(store, data->e0);
        struct entity *e1 = entity_from_handle(store, data->e1);

        if (entity_is_valid_and_active(e0) && entity_is_valid_and_active(e1)) {
            /* Bullet hit entity */
            if (entity_has_prop(e0, ENTITY_PROP_BULLET) || entity_has_prop(e1, ENTITY_PROP_BULLET)) {
                struct v2 normal = data->normal;        /* Impact normal */
                struct v2 vrel = v2_neg(data->vrel);    /* Impact velocity */

                struct entity *target = e0;
                struct entity *bullet = e1;
                if (entity_has_prop(e0, ENTITY_PROP_BULLET)) {
                    target = e1;
                    bullet = e0;
                    normal = v2_neg(normal);
                    vrel = v2_neg(vrel);
                }
                struct entity *src = entity_from_handle(store, bullet->bullet_src);

                if (bullet->bullet_has_hit || entity_handle_eq(src->top, target->top)) {
                    /* Ignore collision if bullet already spent or if weapon and
                     * target share same top level parent */
                    /* NOTE: Since bullet is most likely just a sensor skip_solve is probably already true */
                    constraint->skip_solve = true;
                } else {
                    struct v2 point = data->point;

                    /* Update bullet */
                    bullet->bullet_has_hit = true;
                    entity_enable_prop(bullet, ENTITY_PROP_RELEASE_THIS_TICK);

                    /* Update tracer */
                    struct entity *tracer = entity_from_handle(store, bullet->bullet_tracer);
                    if (entity_is_valid_and_active(tracer)) {
                        struct xform xf = entity_get_xform(tracer);
                        xf.og = point;
                        entity_set_xform(tracer, xf);
                        entity_set_linear_velocity(tracer, V2(0, 0));
                    }

                    /* Update target */
                    struct v2 knockback = v2_mul(v2_norm(vrel), bullet->bullet_knockback);
                    entity_apply_linear_impulse(target, knockback, point);

                    /* Create test blood */
                    /* TODO: Remove this */
                    {
                        struct xform xf = XFORM_TRS(.t = point, .r = sys_rand_f32(0, TAU));
                        struct entity *decal = entity_alloc(root);
                        decal->sprite = sprite_tag_from_path(STR("res/graphics/blood.ase"));
                        decal->sprite_tint = RGBA_32_F(1, 1, 1, 0.25f);
                        entity_set_xform(decal, xf);

                        f32 perp_range = 0.5;
                        struct v2 linear_velocity = v2_mul(normal, 0.5);
                        linear_velocity = v2_add(linear_velocity, v2_mul(v2_perp(normal), sys_rand_f32(-perp_range, perp_range)));

                        f32 angular_velocity_range = 5;
                        f32 angular_velocity = sys_rand_f32(-angular_velocity_range, angular_velocity_range);

                        entity_enable_prop(decal, ENTITY_PROP_PHYSICAL_KINEMATIC);
                        entity_set_linear_velocity(decal, linear_velocity);
                        entity_set_angular_velocity(decal, angular_velocity);

                        decal->linear_damping = 5.0f;
                        decal->angular_damping = 5.0f;
                    }
                }
            }
        }
    }
}

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

INTERNAL void publish_game_tick(void)
{
    __prof;
    struct sys_lock lock = sys_mutex_lock_e(&G.prev_tick_mutex);
    arena_set_readwrite(&G.prev_tick.entity_store->arena);
    {
        world_copy_replace(&G.prev_tick, &G.tick);
    }
    arena_set_readonly(&G.prev_tick.entity_store->arena);
    atomic_u64_eval_exchange(&G.prev_tick_id, G.prev_tick.tick_id);
    atomic_u64_eval_exchange(&G.prev_tick_continuity_gen, G.prev_tick.continuity_gen);
    sys_mutex_unlock(&lock);
}

INTERNAL void game_update(struct game_cmd_array game_cmds)
{
    __prof;

    struct temp_arena scratch = scratch_begin_no_conflict();

    /* ========================== *
     * Reset level if necessary
     * ========================== */

    if (G.should_reset_level) {
        logf_info("Clearing level");
        G.should_reset_level = false;
        G.extra_spawn = false;
        reset_world();
    }

    /* ========================== *
     * Begin frame
     * ========================== */

    ++G.tick.tick_id;
    G.tick.tick_ts = sys_timestamp();
    G.tick.dt = max_f64(0.0, (1.0 / GAME_FPS) * G.tick.timescale);
    G.tick.time += G.tick.dt;

    f64 dt = G.tick.dt;
    f64 time = G.tick.time;
    G.sprite_frame_scope = sprite_scope_begin();
    G.root = entity_from_handle(G.tick.entity_store, G.tick.entity_store->root);

    struct entity *root = G.root;
    struct entity_store *store = G.tick.entity_store;
    struct sprite_scope *sprite_frame_scope = G.sprite_frame_scope;

    (UNUSED)dt;
    (UNUSED)time;

    /* ========================== *
     * Spawn test entities
     * ========================== */

     /* TODO: remove this (testing) */
     /* Initialize entities */
    {
        static b32 run = 0;
        if (!run) {
            run = 1;
            spawn_test_entities();
        }
    }

    /* ========================== *
     * Process global game cmds
     * ========================== */

    for (u64 cmd_index = 0; cmd_index < game_cmds.count; ++cmd_index) {
        struct game_cmd cmd = game_cmds.cmds[cmd_index];

        switch (cmd.kind) {
            /* Cursor */
            case GAME_CMD_KIND_CURSOR_MOVE:
            {
                G.user_cursor = cmd.cursor_pos;
            } break;

            /* Clear level */
            case GAME_CMD_KIND_CLEAR_ALL:
            {
                G.should_reset_level = true;
            } break;

            /* Spawn test */
            case GAME_CMD_KIND_SPAWN_TEST:
            {
                logf_info("Spawning (test)");
                spawn_test_entities();
            } break;
            default: break;
        };
    }

    /* ========================== *
     * Release entities
     * ========================== */

    release_entities_with_prop(ENTITY_PROP_RELEASE_NEXT_TICK);

    /* ========================== *
     * Activate entities
     * ========================== */

    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!ent->valid) continue;

        if (!entity_has_prop(ent, ENTITY_PROP_ACTIVE)) {
            u64 atick = ent->activation_tick;
            if (atick != 0 || G.tick.tick_id >= atick) {
                entity_activate(ent, G.tick.tick_id);
            }
        }
    }

    /* ========================== *
     * Reset triggered entities
     * ========================== */

    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!entity_is_valid_and_active(ent)) continue;

        if (entity_has_prop(ent, ENTITY_PROP_TRIGGER_NEXT_TICK)) {
            entity_disable_prop(ent, ENTITY_PROP_TRIGGER_NEXT_TICK);
            entity_enable_prop(ent, ENTITY_PROP_TRIGGERED_THIS_TICK);
        } else if (entity_has_prop(ent, ENTITY_PROP_TRIGGERED_THIS_TICK)) {
            entity_disable_prop(ent, ENTITY_PROP_TRIGGERED_THIS_TICK);
        }
    }

    /* ========================== *
     * Update entity from sprite
     * ========================== */

    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!entity_is_valid_and_active(ent)) continue;
        if (sprite_tag_is_nil(ent->sprite)) continue;

        /* Update animation */

        struct sprite_sheet *sheet = sprite_sheet_from_tag_await(sprite_frame_scope, ent->sprite);
        {
            struct sprite_sheet_span span = sprite_sheet_get_span(sheet, ent->sprite_span_name);

            f64 time_in_frame = ent->animation_time_in_frame + dt;
            u64 frame_index = ent->animation_frame;
            if (frame_index < span.start || frame_index > span.end) {
                frame_index = span.start;
            }

            struct sprite_sheet_frame frame = sprite_sheet_get_frame(sheet, frame_index);
            while (time_in_frame > frame.duration) {
                time_in_frame -= frame.duration;
                ++frame_index;
                if (frame_index > span.end) {
                    /* Loop animation */
                    frame_index = span.start;
                }
                frame = sprite_sheet_get_frame(sheet, frame_index);
            }

            ent->animation_time_in_frame = time_in_frame;
            ent->animation_frame = frame_index;
        }

        /* Update sprite local xform */
        {
            struct sprite_sheet_slice slice = sprite_sheet_get_slice(sheet, STR("pivot"), ent->animation_frame);
            struct v2 sprite_size = v2_div(sheet->frame_size, (f32)PIXELS_PER_UNIT);

            struct v2 dir = v2_mul_v2(sprite_size, slice.dir);
            f32 rot = v2_angle(dir) + PI / 2;

            struct xform xf = XFORM_IDENT;
            xf = xform_rotated(xf, -rot);
            xf = xform_scaled(xf, sprite_size);
            xf = xform_translated(xf, v2_neg(slice.center));
            ent->sprite_local_xform = xf;
        }

        /* Update collider from sprite */
        if (ent->sprite_collider_slice.len > 0) {
            struct xform cxf = ent->sprite_local_xform;

#if 0
            if (entity_has_prop(ent, ENTITY_PROP_TEST)) {
                f32 scale = 0.5;
                cxf = xform_scaled(cxf, V2(scale, scale));
            }
#endif

            struct sprite_sheet_slice slice = sprite_sheet_get_slice(sheet, ent->sprite_collider_slice, ent->animation_frame);
            ent->local_collider = collider_from_quad(xform_mul_quad(cxf, quad_from_rect(slice.rect)));

#if 1
            if (entity_has_prop(ent, ENTITY_PROP_TEST)) {
            //if ((true)) {
#if 0
                ent->local_collider.points[0] = V2(0, 0);
                ent->local_collider.count = 1;
                ent->local_collider.radius = 0.5;
#elif 1
                ent->local_collider.points[0] = v2_with_len(V2(0.08f, 0.17f), 0.15f);
                ent->local_collider.points[1] = v2_with_len(V2(-0.07f, -0.2f), 0.15f);
                ent->local_collider.count = 2;
                ent->local_collider.radius = 0.075f;
#elif 1
#if 0
                /* "Bad" winding order */
                ent->local_collider.points[0] = V2(-0.15, 0.15);
                ent->local_collider.points[1] = V2(0.15, 0.15);
                ent->local_collider.points[2] = V2(0, -0.15);
#else
                ent->local_collider.points[0] = V2(0, -0.15);
                ent->local_collider.points[1] = V2(0.15, 0.15);
                ent->local_collider.points[2] = V2(-0.15, 0.15);
#endif
                ent->local_collider.count = 3;
                ent->local_collider.radius = 0.25;
                //ent->local_collider.radius = math_fabs(math_sin(G.tick.time) / 3);
#else
                //ent->local_collider.radius = 0.5;
                ent->local_collider.radius = 0.25;
                //ent->local_collider.radius = 0.;
#endif
            }
#endif
        }
    }

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

    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!entity_is_valid_and_active(ent)) continue;
        if (!entity_has_prop(ent, ENTITY_PROP_ATTACHED)) continue;

        struct entity *parent = entity_from_handle(store, ent->parent);
        struct sprite_tag parent_sprite = parent->sprite;
        struct sprite_sheet *parent_sheet = sprite_sheet_from_tag_await(sprite_frame_scope, parent_sprite);

        struct xform parent_sprite_xf = parent->sprite_local_xform;

        struct sprite_sheet_slice attach_slice = sprite_sheet_get_slice(parent_sheet, ent->attach_slice, parent->animation_frame);
        struct v2 attach_pos = xform_mul_v2(parent_sprite_xf, attach_slice.center);
        struct v2 attach_dir = xform_basis_mul_v2(parent_sprite_xf, attach_slice.dir);

        struct xform xf = entity_get_local_xform(ent);
        xf.og = attach_pos;
        xf = xform_basis_with_rotation_world(xf, v2_angle(attach_dir) + PI / 2);
        entity_set_local_xform(ent, xf);
    }

    /* ========================== *
     * Update control from player cmds
     * ========================== */

    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!entity_is_valid_and_active(ent)) continue;

        if (entity_has_prop(ent, ENTITY_PROP_PLAYER_CONTROLLED)) {
            /* Process cmds */
            struct v2 move = ent->control.move;
            struct v2 focus = ent->control.focus;
            b32 firing = entity_has_prop(ent, ENTITY_PROP_TRIGGERING_EQUIPPED);

            for (u64 i = 0; i < game_cmds.count; ++i) {
                struct game_cmd cmd = game_cmds.cmds[i];
                b32 start = cmd.state == GAME_CMD_STATE_START;
                b32 stop = cmd.state == GAME_CMD_STATE_STOP;

                /* TODO: Combine movement from multiple inputs? E.G. a sudden
                 * start and immediate stop cmd should still move the player a
                 * tad. */
                switch (cmd.kind) {
                    case GAME_CMD_KIND_PLAYER_MOVE:
                    {
                        move = cmd.move_dir;
                        focus = cmd.aim_dir;
                    } break;

                    case GAME_CMD_KIND_PLAYER_FIRE:
                    {
                        if (start) {
                            firing = true;
                        } else if (stop) {
                            firing = false;
                        }
                    } break;

                    default: break;
                }
            }

            /* Movement */
            if (v2_len_sq(move) > 1) {
                /* Cap movement vector magnitude at 1 */
                move = v2_norm(move);
            }
            ent->control.move = move;
            ent->control.focus = focus;

            /* Firing */
            if (firing) {
                entity_enable_prop(ent, ENTITY_PROP_TRIGGERING_EQUIPPED);
            } else {
                entity_disable_prop(ent, ENTITY_PROP_TRIGGERING_EQUIPPED);
            }
        }
    }

    /* ========================== *
     * Test
     * ========================== */

#if 0
    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!entity_is_valid_and_active(ent)) continue;
        if (!entity_has_prop(ent, ENTITY_PROP_TEST)) continue;

#if 0
        if (!ent->test_initialized) {
            ent->test_initialized = true;
            ent->test_start_local_xform = entity_get_local_xform(ent);
            ent->test_start_sprite_xform = ent->sprite_local_xform;
        }

        f32 t = (f32)time;
        struct v2 og = v2_mul(V2(math_cos(t), math_sin(t)), 3);
        f32 r = t * 3;
        struct v2 s = V2(1 + (math_fabs(math_sin(t * 5)) * 3), 1);
        (UNUSED)og;
        (UNUSED)r;
        (UNUSED)s;

        og = v2_add(og, ent->test_start_local_xform.og);
        r += xform_get_rotation(ent->test_start_local_xform);
        s = v2_add(s, xform_get_scale(ent->test_start_local_xform));

        struct xform xf = entity_get_local_xform(ent);
        xf.og = og;
        xf = xform_rotated_to(xf, r);
        xf = xform_scaled_to(xf, s);
        entity_set_local_xform(ent, xf);
#else
        f32 t = (f32)time;
        struct v2 og = v2_mul(V2(math_cos(t), math_sin(t)), 3);
        f32 rot = t * PI / 3;
        struct v2 scale = V2(1 + (math_fabs(math_sin(t * 5)) * 3), 1);
        (UNUSED)og;
        (UNUSED)rot;
        (UNUSED)scale;

        struct xform xf = entity_get_local_xform(ent);
        xf = xform_rotated_to(xf, rot);
        xf = xform_scaled_to(xf, scale);
        entity_set_local_xform(ent, xf);
#endif
    }
#endif

    /* ========================== *
     * Trigger equipped
     * ========================== */

    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!entity_is_valid_and_active(ent)) continue;

        if (entity_has_prop(ent, ENTITY_PROP_TRIGGERING_EQUIPPED)) {
            struct entity *eq = entity_from_handle(store, ent->equipped);
            if (entity_is_valid_and_active(eq)) {
                entity_enable_prop(eq, ENTITY_PROP_TRIGGERED_THIS_TICK);
            }
        }
    }

    /* ========================== *
     * Process triggered entities
     * ========================== */

    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!entity_is_valid_and_active(ent)) continue;
        if (!entity_has_prop(ent, ENTITY_PROP_TRIGGERED_THIS_TICK)) continue;
        if ((time - ent->last_triggered < ent->trigger_delay) && ent->last_triggered != 0) continue;

        ent->last_triggered = time;

        /* Fire weapon */
        if (entity_has_prop(ent, ENTITY_PROP_WEAPON)) {
            struct sprite_tag sprite = ent->sprite;
            u32 animation_frame = ent->animation_frame;
            struct sprite_sheet *sheet = sprite_sheet_from_tag_await(sprite_frame_scope, sprite);

            struct xform sprite_local_xform = ent->sprite_local_xform;

            struct sprite_sheet_slice out_slice = sprite_sheet_get_slice(sheet, STR("out"), animation_frame);
            struct v2 rel_pos = xform_mul_v2(sprite_local_xform, out_slice.center);
            struct v2 rel_dir = xform_basis_mul_v2(sprite_local_xform, out_slice.dir);

            /* Spawn bullet */
            struct entity *bullet;
            {
                bullet = entity_alloc(root);

                bullet->bullet_src = ent->handle;
                bullet->bullet_src_pos = rel_pos;
                bullet->bullet_src_dir = rel_dir;
                bullet->bullet_impulse = 0.75f;
                bullet->bullet_knockback = 10;
                bullet->mass_unscaled = 0.04f;
                bullet->inertia_unscaled = 0.00001f;

                /* Point collider */
                bullet->local_collider.points[0] = V2(0, 0);
                bullet->local_collider.count = 1;

                entity_enable_prop(bullet, ENTITY_PROP_BULLET);
                entity_enable_prop(bullet, ENTITY_PROP_SENSOR);
            }

            /* Spawn tracer */
            {
                struct entity *tracer = entity_alloc(root);
                tracer->tracer_fade_duration = 0.025f;
                entity_enable_prop(tracer, ENTITY_PROP_TRACER);

                bullet->bullet_tracer = tracer->handle;
            }
        }
    }

    /* ========================== *
     * Create forces from control move
     * ========================== */

#if 0
    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!entity_is_valid_and_active(ent)) continue;

        if (entity_has_prop(ent, ENTITY_PROP_PLAYER_CONTROLLED)) {
            struct v2 move = ent->control.move;
            struct v2 force = v2_mul(move, ent->control_force);
            entity_apply_force_to_center(ent, force);
        }
    }
#else
    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!entity_is_valid_and_active(ent)) continue;

        if (entity_has_prop(ent, ENTITY_PROP_PLAYER_CONTROLLED)) {
            struct entity *joint_ent = entity_from_handle(store, ent->move_joint);
            if (!entity_is_valid_and_active(joint_ent)) {
                joint_ent = entity_alloc(root);
                joint_ent->mass_unscaled = F32_INFINITY;
                joint_ent->inertia_unscaled = F32_INFINITY;
                entity_enable_prop(joint_ent, ENTITY_PROP_MOTOR_JOINT);
                entity_enable_prop(joint_ent, ENTITY_PROP_ACTIVE);
                ent->move_joint = joint_ent->handle;

                struct phys_motor_joint_def def = ZI;
                def.e0 = joint_ent->handle;  /* Re-using joint entity as e0 */
                def.e1 = ent->handle;
                def.correction_rate = 0;
                def.max_force = ent->control_force;
                def.max_torque = 0;
                joint_ent->motor_joint_data = motor_joint_from_def(def);
            }

            entity_set_xform(joint_ent, XFORM_IDENT);  /* Reset joint ent position */
            entity_set_linear_velocity(joint_ent, v2_mul(v2_clamp_len(ent->control.move, 1), ent->control_force_max_speed));
        }
    }
#endif

    /* ========================== *
     * Create forces from control focus (aim)
     * ========================== */

#if GAME_PLAYER_AIM
    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!entity_is_valid_and_active(ent)) continue;

        if (entity_has_prop(ent, ENTITY_PROP_PLAYER_CONTROLLED)) {
            struct xform xf = entity_get_xform(ent);
            struct xform sprite_xf = xform_mul(xf, ent->sprite_local_xform);

            /* Retrieve / create aim joint */
            struct entity *joint_ent = entity_from_handle(store, ent->aim_joint);
            if (!entity_is_valid_and_active(joint_ent)) {
                joint_ent = entity_alloc(root);
                joint_ent->mass_unscaled = F32_INFINITY;
                joint_ent->inertia_unscaled = F32_INFINITY;
                entity_enable_prop(joint_ent, ENTITY_PROP_PHYSICAL_KINEMATIC);  /* Since we'll be setting velocity */
                entity_enable_prop(joint_ent, ENTITY_PROP_MOTOR_JOINT);
                entity_enable_prop(joint_ent, ENTITY_PROP_ACTIVE);
                ent->aim_joint = joint_ent->handle;

                struct phys_motor_joint_def def = ZI;
                def.e0 = joint_ent->handle;  /* Re-using joint entity as e0 */
                def.e1 = ent->handle;
                def.correction_rate = 0.1f;
                def.max_force = 0;
                def.max_torque = ent->control_torque;
                joint_ent->motor_joint_data = motor_joint_from_def(def);
            }

            /* Solve for final angle using law of sines */
            f32 new_angle;
            {
                struct v2 ent_pos = xf.og;
                struct v2 focus_pos = v2_add(ent_pos, ent->control.focus);

                struct v2 sprite_hold_pos;
                struct v2 sprite_hold_dir;
                {
                    struct sprite_sheet *sheet = sprite_sheet_from_tag_await(sprite_frame_scope, ent->sprite);
                    struct sprite_sheet_slice slice = sprite_sheet_get_slice(sheet, STR("attach.wep"), ent->animation_frame);
                    sprite_hold_pos = slice.center;
                    sprite_hold_dir = slice.dir;
                }

                struct v2 hold_dir = xform_basis_mul_v2(sprite_xf, sprite_hold_dir);
                struct v2 hold_pos = xform_mul_v2(sprite_xf, sprite_hold_pos);
                if (v2_eq(hold_pos, ent_pos)) {
                    /* If hold pos is same as origin (E.G if pivot is being used as hold pos), then move hold pos forward a tad to avoid issue */
                    sprite_hold_pos = v2_add(sprite_hold_pos, V2(0, -1));
                    hold_pos = xform_mul_v2(sprite_xf, sprite_hold_pos);
                }

                f32 forward_hold_angle_offset;
                {
                    struct xform xf_unrotated = xform_basis_with_rotation_world(xf, 0);
                    struct v2 hold_pos_unrotated = xform_mul_v2(xf_unrotated, xform_mul_v2(ent->sprite_local_xform, sprite_hold_pos));
                    forward_hold_angle_offset = v2_angle_from_dirs(V2(0, -1), v2_sub(hold_pos_unrotated, xf_unrotated.og));
                }

                struct v2 hold_ent_dir = v2_sub(ent_pos, hold_pos);
                struct v2 focus_ent_dir = v2_sub(ent_pos, focus_pos);

                f32 hold_ent_len = v2_len(hold_ent_dir);
                f32 focus_ent_len = v2_len(focus_ent_dir);

                f32 final_hold_angle_btw_ent_and_focus = v2_angle_from_dirs(hold_ent_dir, hold_dir);
                f32 final_focus_angle_btw_ent_and_hold = math_asin((math_sin(final_hold_angle_btw_ent_and_focus) * hold_ent_len) / focus_ent_len);
                f32 final_ent_angle_btw_focus_and_hold = PI - (final_focus_angle_btw_ent_and_hold + final_hold_angle_btw_ent_and_focus);

                new_angle = math_unwind_angle(v2_angle_from_dirs(V2(0, -1), v2_sub(focus_pos, ent_pos)) + final_ent_angle_btw_focus_and_hold - forward_hold_angle_offset);
            }

            f32 new_vel = 0;
            if (!F32_IS_NAN(new_angle)) {
                const f32 angle_error_allowed = 0.001f;
                struct xform joint_xf = entity_get_xform(joint_ent);
                f32 diff = math_unwind_angle(new_angle - xform_get_rotation(joint_xf));
                if (math_fabs(diff) > angle_error_allowed) {
                    new_vel = diff / dt;
                }
            }
            entity_set_angular_velocity(joint_ent, new_vel);
        }
    }
#endif

    /* ========================== *
     * Create ground friction force (gravity)
     * ========================== */

    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!entity_is_valid_and_active(ent)) continue;
        if (!entity_has_prop(ent, ENTITY_PROP_PHYSICAL_DYNAMIC)) continue;

        struct entity *joint_ent = entity_from_handle(store, ent->ground_friction_joint);

        struct phys_motor_joint_def def = ZI;
        def.e0 = root->handle;
        def.e1 = ent->handle;
        def.correction_rate = 0;
        def.max_force = ent->linear_ground_friction;
        def.max_torque = ent->angular_ground_friction;
        if (joint_ent->motor_joint_data.max_force != def.max_force || joint_ent->motor_joint_data.max_torque != def.max_torque) {
            if (!entity_is_valid_and_active(joint_ent)) {
                joint_ent = entity_alloc(root);
                entity_enable_prop(joint_ent, ENTITY_PROP_MOTOR_JOINT);
                entity_enable_prop(joint_ent, ENTITY_PROP_ACTIVE);
                joint_ent->motor_joint_data = motor_joint_from_def(def);
                ent->ground_friction_joint = joint_ent->handle;
            }
        }
    }

    /* ========================== *
     * Physics
     * ========================== */

    {
        struct phys_ctx ctx = ZI;
        ctx.tick_id = G.tick.tick_id;
        ctx.store = store;
        ctx.contact_lookup = &G.contact_lookup;
        ctx.pre_solve_callback = on_collision;
#if COLLIDER_DEBUG
        ctx.debug_lookup = &G.collision_debug_lookup;
#endif

        /* Mouse drag */
        ctx.dbg_cursor_pos = G.user_cursor;
        for (u64 i = 0; i < game_cmds.count; ++i) {
            struct game_cmd cmd = game_cmds.cmds[i];
            if (cmd.kind == GAME_CMD_KIND_DRAG_OBJECT) {
                if (cmd.state == GAME_CMD_STATE_START) {
                    ctx.dbg_start_dragging = true;
                } else if (cmd.state == GAME_CMD_STATE_STOP) {
                    ctx.dbg_stop_dragging = true;
                }
            }
        }

        phys_step(&ctx, dt);
    }

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

    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!entity_is_valid_and_active(ent)) continue;
        if (!entity_has_prop(ent, ENTITY_PROP_TRACER)) continue;

        struct v2 end = entity_get_xform(ent).og;

        struct v2 tick_velocity = v2_mul(ent->tracer_start_velocity, dt);
        struct v2 gradient_start = v2_add(ent->tracer_gradient_start, tick_velocity);
        struct v2 gradient_end = v2_add(ent->tracer_gradient_end, tick_velocity);

        if (v2_dot(tick_velocity, v2_sub(gradient_start, end)) > 0) {
            /* Tracer has disappeared */
            entity_enable_prop(ent, ENTITY_PROP_RELEASE_NEXT_TICK);
        }

        ent->tracer_gradient_start = gradient_start;
        ent->tracer_gradient_end = gradient_end;
    }

    /* ========================== *
     * Initialize bullet kinematics from sources
     * ========================== */

    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!entity_is_valid_and_active(ent)) continue;
        if (!entity_has_prop(ent, ENTITY_PROP_BULLET)) continue;

        if (ent->activation_tick == G.tick.tick_id) {
            struct entity *src = entity_from_handle(store, ent->bullet_src);
            struct xform src_xf = entity_get_xform(src);

            struct v2 pos = xform_mul_v2(src_xf, ent->bullet_src_pos);
            struct v2 impulse = xform_basis_mul_v2(src_xf, ent->bullet_src_dir);
            impulse = v2_with_len(impulse, ent->bullet_impulse);

#if 0
            /* Add shooter velocity to bullet */
            {
                /* TODO: Add angular velocity as well? */
                struct entity *top = entity_from_handle(store, src->top);
                impulse = v2_add(impulse, v2_mul(top->linear_velocity, dt));
            }
#endif

            struct xform xf = XFORM_TRS(.t = pos, .r = v2_angle(impulse) + PI / 2);
            entity_set_xform(ent, xf);
            entity_enable_prop(ent, ENTITY_PROP_PHYSICAL_KINEMATIC);

            entity_apply_linear_impulse_to_center(ent, impulse);

            /* Initialize tracer */
            struct entity *tracer = entity_from_handle(store, ent->bullet_tracer);
            if (entity_is_valid_and_active(tracer)) {
                entity_set_xform(tracer, xf);
                entity_enable_prop(tracer, ENTITY_PROP_PHYSICAL_KINEMATIC);
                entity_set_linear_velocity(tracer, ent->linear_velocity);
                tracer->tracer_start = pos;
                tracer->tracer_start_velocity = ent->linear_velocity;
                tracer->tracer_gradient_end = pos;
                tracer->tracer_gradient_start = v2_sub(pos, v2_mul(ent->linear_velocity, tracer->tracer_fade_duration));
            }
        }
    }

    /* ========================== *
     * Update camera position
     * ========================== */

    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!entity_is_valid_and_active(ent)) continue;

        /* Camera follow */
        if (entity_has_prop(ent, ENTITY_PROP_CAMERA)) {
            struct entity *follow = entity_from_handle(store, ent->camera_follow);

            struct xform xf = entity_get_xform(ent);

            f32 aspect_ratio = 1.0;
            {
                struct xform quad_xf = xform_mul(entity_get_xform(ent), ent->camera_quad_xform);
                struct v2 camera_size = xform_get_scale(quad_xf);
                if (!v2_is_zero(camera_size)) {
                    aspect_ratio = camera_size.x / camera_size.y;
                }
            }
            f32 ratio_y = 0.33f;
            f32 ratio_x = ratio_y / aspect_ratio;
            struct v2 camera_focus_dir = v2_mul_v2(follow->control.focus, V2(ratio_x, ratio_y));
            struct v2 camera_focus_pos = v2_add(entity_get_xform(follow).og, camera_focus_dir);
            ent->camera_xform_target = xf;
            ent->camera_xform_target.og = camera_focus_pos;

            /* Lerp camera */
            if (ent->camera_applied_lerp_continuity_gen_plus_one == ent->camera_lerp_continuity_gen + 1) {
                f32 t = 1 - math_pow(2.f, -20.f * (f32)G.tick.dt);
                xf = xform_lerp(xf, ent->camera_xform_target, t);
            } else {
                /* Skip lerp */
                xf = ent->camera_xform_target;
            }
            ent->camera_applied_lerp_continuity_gen_plus_one = ent->camera_lerp_continuity_gen + 1;
            entity_set_xform(ent, xf);
        }
    }

    /* ========================== *
     * Update sound emitters
     * ========================== */

     /* TODO: Sound entities should be created by game thread, but played by the
      * user thread. This is so sounds play at the correct time on the user
      * thread regardless of interp delay. */

    for (u64 entity_index = 0; entity_index < store->reserved; ++entity_index) {
        struct entity *ent = &store->entities[entity_index];
        if (!entity_is_valid_and_active(ent)) continue;

        if (entity_has_prop(ent, ENTITY_PROP_TEST_SOUND_EMITTER)) {
            struct mixer_desc desc = ent->sound_desc;
            desc.speed = G.tick.timescale;

            desc.pos = entity_get_xform(ent).og;
            struct sound *sound = sound_load_async(ent->sound_name, 0);
            b32 played = ent->sound_handle.gen != 0;
            if (sound) {
                if (!played) {
                    ent->sound_handle = mixer_play_ex(sound, desc);
                } else {
                    mixer_track_set(ent->sound_handle, desc);
                }
            }
        }
    }

    /* ========================== *
     * Release entities
     * ========================== */

    release_entities_with_prop(ENTITY_PROP_RELEASE_THIS_TICK);

    /* ========================== *
     * Publish tick
     * ========================== */

    /* Publish tick */
    publish_game_tick();
    __profframe("Game");

    /* ========================== *
     * End frame cache scopes
     * ========================== */

    sprite_scope_end(sprite_frame_scope);

    scratch_end(scratch);
}

/* ========================== *
 * Game thread
 * ========================== */

INTERNAL SYS_THREAD_ENTRY_POINT_FUNC_DEF(game_thread_entry_point, arg)
{
    struct temp_arena scratch = scratch_begin_no_conflict();

    (UNUSED)arg;
    sys_timestamp_t last_frame_ts = 0;
    f64 target_dt = GAME_FPS > (0) ? (1.0 / GAME_FPS) : 0;
    while (!atomic_i32_eval(&G.game_thread_shutdown)) {
        __profscope(game_update_w_sleep);
        struct temp_arena temp = arena_temp_begin(scratch.arena);
        sleep_frame(last_frame_ts, target_dt);
        last_frame_ts = sys_timestamp();
        {
            struct game_cmd_array game_cmds = pop_cmds(temp.arena);
            if (!G.paused) {
                game_update(game_cmds);
            }
            /* Check for pause / next frame cmds */
            for (u64 i = 0; i < game_cmds.count; ++i) {
                struct game_cmd cmd = game_cmds.cmds[i];
                switch (cmd.kind) {
                    case GAME_CMD_KIND_PAUSE: {
                        G.paused = !G.paused;
                    } break;

                    case GAME_CMD_KIND_STEP: {
                        if (G.paused) {
                            G.paused = false;
                            game_update(game_cmds);
                            G.paused = true;
                        }
                    } break;

                    default: break;
                }
            }
        }
        arena_temp_end(temp);
    }

    scratch_end(scratch);
}

/* ========================== *
 * Interface
 * ========================== */

void game_get_latest_tick(struct world *dest)
{
    __prof;
    struct sys_lock lock = sys_mutex_lock_s(&G.prev_tick_mutex);
    world_copy_replace(dest, &G.prev_tick);
    sys_mutex_unlock(&lock);
}

u64 game_get_latest_tick_id(void)
{
    return atomic_u64_eval(&G.prev_tick_id);
}

u64 game_get_latest_tick_continuity_gen(void)
{
    return atomic_u64_eval(&G.prev_tick_continuity_gen);
}

void game_push_cmds(struct game_cmd_array cmd_array)
{
    push_cmds(cmd_array);
}