#include "zpl.h"
#include "ecs/systems.h"
#include "ecs/components.h"
#include "world/world.h"
#include "world/blocks.h"
#include "platform/profiler.h"
#include "debug/debug_draw.h"
#include "core/game.h"
#include "core/rules.h"

#define PHY_BLOCK_COLLISION 1
#define PHY_WALK_DRAG 4.23f
#define PHY_LOOKAHEAD(x) (zpl_sign(x)*16.0f)

#include "modules/system_onfoot.c"
#include "modules/system_demo.c"
#include "modules/system_vehicle.c"
#include "modules/system_items.c"
#include "modules/system_furnace.c"

static inline float physics_correction(float x, float vx, float bounce) {
    float r = (((zpl_max(0.0f, (WORLD_BLOCK_SIZE/2.0f) - zpl_abs(x))*zpl_sign(x)))*(WORLD_BLOCK_SIZE/2.0f));
    return r + (-vx*bounce);
}

void IntegratePositions(ecs_iter_t *it) {
    profile(PROF_INTEGRATE_POS) {
        Position *p = ecs_field(it, Position, 1);
        Velocity *v = ecs_field(it, Velocity, 2);

        for (int i = 0; i < it->count; i++) {
            if (ecs_get(it->world, it->entities[i], IsInVehicle)) {
                continue;
            }
            if (zpl_abs(v[i].x) >= 0.001f || zpl_abs(v[i].y) >= 0.001f) {
                // NOTE(zaklaus): world bounds
                {
                    float w = (float)world_dim();
                    p[i].x = zpl_clamp(p[i].x, 0, w-1);
                    p[i].y = zpl_clamp(p[i].y, 0, w-1);
                }

    #if PHY_BLOCK_COLLISION==1
                // NOTE(zaklaus): X axis
                {
                    world_block_lookup lookup = world_block_from_realpos(p[i].x+PHY_LOOKAHEAD(v[i].x), p[i].y);
                    uint32_t flags = blocks_get_flags(lookup.bid);
                    float bounce = blocks_get_bounce(lookup.bid);
                    if (flags & BLOCK_FLAG_COLLISION) {
                        v[i].x = physics_correction(lookup.ox, v[i].x, bounce);
                    }
                }

                // NOTE(zaklaus): Y axis
                {
                    world_block_lookup lookup = world_block_from_realpos(p[i].x, p[i].y+PHY_LOOKAHEAD(v[i].y));
                    uint32_t flags = blocks_get_flags(lookup.bid);
                    float bounce = blocks_get_bounce(lookup.bid);
                    if (flags & BLOCK_FLAG_COLLISION) {
                        v[i].y = physics_correction(lookup.oy, v[i].y, bounce);
                    }
                }
    #endif

                entity_set_position(it->entities[i], p[i].x+v[i].x*safe_dt(it), p[i].y+v[i].y*safe_dt(it));
            }

            {
                debug_v2 a = {p[i].x, p[i].y};
                debug_v2 b = {p[i].x+v[i].x, p[i].y+v[i].y};
                debug_push_line(a, b, 0xFFFFFFFF);
            }
        }
    }
}

#define HAZARD_BLOCK_TIME 1.0f
#define HAZARD_BLOCK_DMG 5.0f

void HurtOnHazardBlock(ecs_iter_t *it) {
    Position *p = ecs_field(it, Position, 1);
    Health *h = ecs_field(it, Health, 2);

    for (int i = 0; i < it->count; i++) {
        if (h->pain_time < 0.0f) {
            h->pain_time = HAZARD_BLOCK_TIME;
            world_block_lookup l = world_block_from_realpos(p[i].x, p[i].y);
            if (blocks_get_flags(l.bid) & BLOCK_FLAG_HAZARD) {
                h->hp -= HAZARD_BLOCK_DMG;
                h->hp = zpl_max(0.0f, h->hp);
            }
        }
    }
}

#define HP_REGEN_TIME 2.0f
#define HP_REGEN_PAIN_COOLDOWN 5.0f
#define HP_REGEN_RECOVERY 15.0f

void RegenerateHP(ecs_iter_t *it) {
    Health *h = ecs_field(it, Health, 1);

    for (int i = 0; i < it->count; i++) {
        if (h[i].pain_time < 0.0f) {
            if (h[i].heal_time < 0.0f && h[i].hp < h[i].max_hp) {
                h[i].heal_time = HP_REGEN_TIME;
                h[i].hp += HP_REGEN_RECOVERY;
                h[i].hp = zpl_min(h[i].max_hp, h[i].hp);
                entity_wake(it->entities[i]);
            } else {
                h[i].heal_time -= safe_dt(it);
            }
        } else {
            h[i].pain_time -= safe_dt(it);
        }
    }
}

void ResetActivators(ecs_iter_t *it) {
    Input *in = ecs_field(it, Input, 1);

    for (int i = 0; i < it->count; i++) {
        in[i].use = false;
        in[i].swap = false;
        in[i].drop = false;
        in[i].pick = false;
        in[i].num_placements = 0;
    }
}

void ApplyWorldDragOnVelocity(ecs_iter_t *it) {
    Position *p = ecs_field(it, Position, 1);
    Velocity *v = ecs_field(it, Velocity, 2);

    for (int i = 0; i < it->count; i++) {
        if (zpl_abs(v[i].x) < 0.001f && zpl_abs(v[i].y) < 0.001f) continue;
        if (ecs_get(it->world, it->entities[i], IsInVehicle)) {
            continue;
        }
        world_block_lookup lookup = world_block_from_realpos(p[i].x, p[i].y);
        float drag = zpl_clamp(blocks_get_drag(lookup.bid), 0.0f, 1.0f);
        float friction = blocks_get_friction(lookup.bid);
        float velx = blocks_get_velx(lookup.bid);
        float vely = blocks_get_vely(lookup.bid);
        v[i].x = zpl_lerp(v[i].x, zpl_max(0.0f, zpl_abs(velx))*zpl_sign(velx), PHY_WALK_DRAG*drag*friction*safe_dt(it));
        v[i].y = zpl_lerp(v[i].y, zpl_max(0.0f, zpl_abs(vely))*zpl_sign(vely), PHY_WALK_DRAG*drag*friction*safe_dt(it));

        if (   zpl_abs(v[i].x) > ENTITY_ACTION_VELOCITY_THRESHOLD
            || zpl_abs(v[i].y) > ENTITY_ACTION_VELOCITY_THRESHOLD) {
            entity_wake(it->entities[i]);
        }
    }
}

#define PLAYER_MAX_INTERACT_RANGE 35.0f

void PlayerClosestInteractable(ecs_iter_t *it){
    Input *in = ecs_field(it, Input, 1);

    for (int i = 0; i < it->count; ++i) {
        size_t ents_count;
        int64_t *ents = world_chunk_fetch_entities_realpos(in[i].bx, in[i].by, &ents_count);

        ecs_entity_t closest_pick = 0;
        float min_pick = ZPL_F32_MAX;

        for (size_t j = 0; j < ents_count; j++) {
            const Position *p2 = ecs_get(it->world, ents[j], Position);
            if (!p2) continue;

            float dx = p2->x - in[i].bx;
            float dy = p2->y - in[i].by;
            float range = zpl_sqrt(dx*dx + dy*dy);
            if (range <= PLAYER_MAX_INTERACT_RANGE && range < min_pick) {
                min_pick = range;
                closest_pick = ents[j];
            }
        }

        in[i].pick_ent = closest_pick;

        if (in[i].pick)
            in[i].sel_ent = (in[i].sel_ent == closest_pick) ? 0 : closest_pick;
    }
}

void EnableWorldEdit(ecs_iter_t *it) {
    world_set_stage(it->world);
}

void DisableWorldEdit(ecs_iter_t *it) {
    (void)it;
    world_set_stage(NULL);
}

void SystemsImport(ecs_world_t *ecs) {
    ECS_MODULE(ecs, Systems);

    ECS_SYSTEM(ecs, EnableWorldEdit, EcsOnLoad);
    ECS_SYSTEM(ecs, MovementImpulse, EcsOnLoad, components.Input, components.Velocity, components.Position, !components.IsInVehicle);
    ECS_SYSTEM(ecs, DemoNPCMoveAround, EcsOnLoad, components.Velocity, components.DemoNPC);

    ECS_SYSTEM(ecs, ApplyWorldDragOnVelocity, EcsOnUpdate, components.Position, components.Velocity);
    ECS_SYSTEM(ecs, HurtOnHazardBlock, EcsOnUpdate, components.Position, components.Health);
    ECS_SYSTEM(ecs, RegenerateHP, EcsOnUpdate, components.Health);
    ECS_SYSTEM(ecs, VehicleHandling, EcsOnUpdate, components.Vehicle, components.Position, components.Velocity);

    ECS_SYSTEM(ecs, IntegratePositions, EcsOnValidate, components.Position, components.Velocity);

    ECS_SYSTEM(ecs, EnterVehicle, EcsPostUpdate, components.Input, components.Position, !components.IsInVehicle);
    ECS_SYSTEM(ecs, LeaveVehicle, EcsPostUpdate, components.Input, components.IsInVehicle, components.Velocity);

    ECS_SYSTEM(ecs, PlayerClosestInteractable, EcsPostUpdate, components.Input);
    ECS_SYSTEM(ecs, PickItem, EcsPostUpdate, components.Input, components.Position, components.Inventory, !components.IsInVehicle);
    ECS_SYSTEM(ecs, DropItem, EcsPostUpdate, components.Input, components.Position, components.Inventory, !components.IsInVehicle);
    ECS_SYSTEM(ecs, SwapItems, EcsPostUpdate, components.Input, components.Inventory);
    //ECS_SYSTEM(ecs, MergeItems, EcsPostUpdate, components.Position, components.ItemDrop);
    ECS_SYSTEM(ecs, UseItem, EcsPostUpdate, components.Input, components.Position, components.Inventory, !components.IsInVehicle);
    ECS_SYSTEM(ecs, InspectContainers, EcsPostUpdate, components.Input, !components.IsInVehicle);
    ECS_SYSTEM(ecs, HarvestIntoContainers, EcsPostUpdate, components.ItemContainer, components.Position);
    ECS_SYSTEM(ecs, FurnaceCook, EcsPostUpdate, components.ItemContainer, components.Furnace, components.Position);

    ECS_SYSTEM(ecs, ResetActivators, EcsPostUpdate, components.Input);

    ECS_SYSTEM(ecs, ClearVehicle, EcsUnSet, components.Vehicle);

    ECS_SYSTEM(ecs, DisableWorldEdit, EcsPostUpdate);

}