#include <stdbool.h>
#include "sok.h"

#define UNUSED(a) ((void) (a))

static bool
sok_solve_step(
  sok_ctx_t * const ctx,
  sok_cache_t * const cache,
  const sok_solve_cbs_t * const cbs,
  void * const user_data
) {
  // check for success
  if (sok_ctx_is_done(ctx)) {
    // return success
    return true;
  }

  if (sok_cache_has(cache, ctx)) {
    // return failure
    return false;
  }

  // add to cache
  if (!sok_cache_add(cache, ctx)) {
    if (cbs && cbs->on_error) {
      // log error
      cbs->on_error("sok_cache_add() failed", user_data);
    }

    // return failure
    return false;
  }

  if (cbs && cbs->on_step && !cbs->on_step(ctx, user_data)) {
    // return failure
    return false;
  }

  // make sure level is solvable
  if (sok_ctx_is_lost(ctx)) {
    // return failure
    return false;
  }

  for (size_t dir = 0; dir < SOK_DIR_LAST; dir++) {
    if (!sok_ctx_move(ctx, dir)) {
      continue;
    }

    // recurse, check for success
    if (sok_solve_step(ctx, cache, cbs, user_data)) {
      // return success
      return true;
    }

    // undo move
    if (!sok_ctx_undo(ctx)) {
      if (cbs && cbs->on_error) {
        // log error
        cbs->on_error("sok_ctx_undo() failed", user_data);
      }

      // return failure
      return false;
    }
  }

  // return failure
  return false;
}

bool
sok_solve(
  sok_ctx_t * const ctx,
  const sok_solve_cbs_t * const cbs,
  void *user_data
) {
  // init cache
  sok_cache_t cache;
  if (!sok_cache_init(&cache, SOK_CACHE_DEFAULT_CAPACITY)) {
    if (cbs && cbs->on_error) {
      cbs->on_error("sok_cache_init() failed", user_data);
    }

    // return failure
    return false;
  }

  // solve
  const bool r = sok_solve_step(ctx, &cache, cbs, user_data);

  // finalize cache
  sok_cache_fini(&cache);

  // return result
  return r;
}