/**
 * Copyright (c) 2025 Dominic Masters
 * 
 * This software is released under the MIT License.
 * https://opensource.org/licenses/MIT
 */

#include "entity.h"
#include "assert/assert.h"
#include "util/memory.h"
#include "time/time.h"
#include "util/math.h"
#include "rpg/cutscene/cutscenemode.h"
#include "rpg/world/map.h"

entity_t ENTITIES[ENTITY_COUNT];

void entityInit(entity_t *entity, const entitytype_t type) {
  assertNotNull(entity, "Entity pointer cannot be NULL");
  assertTrue(type < ENTITY_TYPE_COUNT, "Invalid entity type");
  assertTrue(type != ENTITY_TYPE_NULL, "Cannot have NULL entity type");
  assertTrue(
    entity >= ENTITIES && entity < ENTITIES + ENTITY_COUNT,
    "Entity pointer is out of bounds"
  );

  memoryZero(entity, sizeof(entity_t));
  entity->id = (uint8_t)(entity - ENTITIES);
  entity->type = type;

  if(ENTITY_CALLBACKS[type].init != NULL) ENTITY_CALLBACKS[type].init(entity);
}

void entityUpdate(entity_t *entity) {
  assertNotNull(entity, "Entity pointer cannot be NULL");
  assertTrue(entity->type < ENTITY_TYPE_COUNT, "Invalid entity type");
  assertTrue(entity->type != ENTITY_TYPE_NULL, "Cannot have NULL entity type");

  // What state is the entity in?
  if(entity->animation != ENTITY_ANIM_IDLE) {
    // Entity is mid animation, tick it (down).
    entity->animTime -= TIME.delta;
    if(entity->animTime <= 0) {
      entity->animation = ENTITY_ANIM_IDLE;
      entity->animTime = 0;
    }
    return;
  }

  // Movement code.
  if(
    cutsceneModeIsInputAllowed() &&
    ENTITY_CALLBACKS[entity->type].movement != NULL
  ) {
    ENTITY_CALLBACKS[entity->type].movement(entity);
  }
}

void entityTurn(entity_t *entity, const entitydir_t direction) {
  entity->direction = direction;
  entity->animation = ENTITY_ANIM_TURN;
  entity->animTime = ENTITY_ANIM_TURN_DURATION;
}

void entityWalk(entity_t *entity, const entitydir_t direction) {
  // TODO: Animation, delay, etc.
  entity->direction = direction;

  // Where are we moving?
  worldpos_t newPos = entity->position;
  {
    worldunits_t relX, relY;
    entityDirGetRelative(direction, &relX, &relY);
    newPos.x += relX;
    newPos.y += relY;
  }

  // Get tile under foot
  tile_t tileCurrent = mapGetTile(entity->position);
  tile_t tileNew = mapGetTile(newPos);
  bool_t fall = false;
  bool_t raise = false;

  // Are we walking up a ramp?
  if(
    tileIsRamp(tileCurrent) &&
    (
      // Can only walk UP the direction the ramp faces.
      (direction+TILE_SHAPE_RAMP_SOUTH) == tileCurrent ||
      // If diagonal ramp, can go up one of two ways only.
      (
        (
          tileCurrent == TILE_SHAPE_RAMP_SOUTHEAST &&
          (direction == ENTITY_DIR_SOUTH || direction == ENTITY_DIR_EAST)
        ) ||
        (
          tileCurrent == TILE_SHAPE_RAMP_SOUTHWEST &&
          (direction == ENTITY_DIR_SOUTH || direction == ENTITY_DIR_WEST)
        ) ||
        (
          tileCurrent == TILE_SHAPE_RAMP_NORTHEAST &&
          (direction == ENTITY_DIR_NORTH || direction == ENTITY_DIR_EAST)
        ) ||
        (
          tileCurrent == TILE_SHAPE_RAMP_NORTHWEST &&
          (direction == ENTITY_DIR_NORTH || direction == ENTITY_DIR_WEST)
        )
      )
    // Must be able to walk up.
    ) && newPos.z < (MAP_CHUNK_DEPTH - 1)
  ) {
    tileNew = TILE_SHAPE_NULL;// Force check for ramp above.
    worldpos_t abovePos = newPos;
    abovePos.z += 1;
    tile_t tileAbove = mapGetTile(abovePos);

    if(tileAbove != TILE_SHAPE_NULL && tileIsWalkable(tileAbove)) {
      // We can go up the ramp.
      raise = true;
    }
  } else if(tileNew == TILE_SHAPE_NULL && newPos.z > 0) {
    // Falling down?
    worldpos_t belowPos = newPos;
    belowPos.z -= 1;
    tile_t tileBelow = mapGetTile(belowPos);
    if(
      tileBelow != TILE_SHAPE_NULL &&
      tileIsRamp(tileBelow) &&
      (
        // This handles regular cardinal ramps
        (entityDirGetOpposite(direction)+TILE_SHAPE_RAMP_SOUTH) == tileBelow ||
        // This handles diagonal ramps
        (
          (
            tileBelow == TILE_SHAPE_RAMP_SOUTHEAST &&
            (direction == ENTITY_DIR_NORTH || direction == ENTITY_DIR_WEST)
          ) ||
          (
            tileBelow == TILE_SHAPE_RAMP_SOUTHWEST &&
            (direction == ENTITY_DIR_NORTH || direction == ENTITY_DIR_EAST)
          ) ||
          (
            tileBelow == TILE_SHAPE_RAMP_NORTHEAST &&
            (direction == ENTITY_DIR_SOUTH || direction == ENTITY_DIR_WEST)
          ) ||
          (
            tileBelow == TILE_SHAPE_RAMP_NORTHWEST &&
            (direction == ENTITY_DIR_SOUTH || direction == ENTITY_DIR_EAST)
          )
        )
      )
    ) {
      // We will fall to this tile.
      fall = true;
    }
  }

  // Can we walk here?
  if(!raise && !fall && !tileIsWalkable(tileNew)) return;// Blocked

  // Entity in way?
  entity_t *other = ENTITIES;
  do {
    if(other == entity) continue;
    if(other->type == ENTITY_TYPE_NULL) continue;
    if(!worldPosIsEqual(other->position, newPos)) continue;
    return;// Blocked
  } while(++other, other < &ENTITIES[ENTITY_COUNT]);

  entity->lastPosition = entity->position;
  entity->position = newPos;
  entity->animation = ENTITY_ANIM_WALK;
  entity->animTime = ENTITY_ANIM_WALK_DURATION;// TODO: Running vs walking

  if(raise) {
    entity->position.z += 1;
  } else if(fall) {
    entity->position.z -= 1;
  }
}

entity_t * entityGetAt(const worldpos_t position) {
  entity_t *ent = ENTITIES;
  do {
    if(ent->type == ENTITY_TYPE_NULL) continue;
    if(!worldPosIsEqual(ent->position, position)) continue;
    return ent;
  } while(++ent, ent < &ENTITIES[ENTITY_COUNT]);

  return NULL;
}

uint8_t entityGetAvailable() {
  entity_t *ent = ENTITIES;
  do {
    if(ent->type == ENTITY_TYPE_NULL) return ent - ENTITIES;
  } while(++ent, ent < &ENTITIES[ENTITY_COUNT]);

  return 0xFF;
}