#include <stdbool.h> // bool
#include <string.h> // atoi()
#include <stdlib.h> // EXIT_{FAILURE,SUCCESS}
#include <stdio.h>
#include "../libsok/sok.h"
#include "levels.h"
#include "action.h"

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

#define warn(fmt, ...) do { \
  fprintf(stderr, "W: " fmt "\n", ##__VA_ARGS__); \
} while (0)

#define die(fmt, ...) do { \
  fprintf(stderr, "ERROR: " fmt "\n", ##__VA_ARGS__); \
  exit(EXIT_FAILURE); \
} while (0)

static char print_buf[(SOK_LEVEL_MAX_WIDTH + 1) * SOK_LEVEL_MAX_HEIGHT + 1];

static bool
draw_on_size(
  const sok_ctx_t * const ctx,
  const sok_pos_t size,
  void * const data
) {
  UNUSED(ctx);
  UNUSED(data);

  // fprintf(stderr, "size: x = %u, y = %u\n", size.x, size.y);

  memset(print_buf, ' ', sizeof(print_buf));
  print_buf[(size.x + 1) * size.y + 1] = '\0';
  for (size_t i = 0; i < size.y; i++) {
    print_buf[(i + 1) * (size.x + 1) - 1] = '\n';
  }

  return true;
}

static bool
draw_on_home(
  const sok_ctx_t * const ctx,
  const sok_pos_t pos,
  const bool has_goal,
  void * const data
) {
  UNUSED(data);
  print_buf[pos.y * (ctx->level.size.x + 1) + pos.x] = has_goal ? '+' : '@';
  return true;
}

static bool
draw_on_wall(
  const sok_ctx_t * const ctx,
  const sok_pos_t pos,
  void * const data
) {
  // fprintf(stderr, "wall: x = %u, y = %u\n", pos.x, pos.y);
  UNUSED(data);
  print_buf[pos.y * (ctx->level.size.x + 1) + pos.x] = '#';
  return true;
}

static bool
draw_on_goal(
  const sok_ctx_t * const ctx,
  const sok_pos_t pos,
  const bool has_player,
  const bool has_box,
  void * const data
) {
  UNUSED(data);
  const char c = has_player ? '+' : (has_box ? '*' : '.');
  print_buf[pos.y * (ctx->level.size.x + 1) + pos.x] = c;
  return true;
}

static bool
draw_on_box(
  const sok_ctx_t * const ctx,
  const sok_pos_t pos,
  const bool has_goal,
  void * const data
) {
  UNUSED(data);
  print_buf[pos.y * (ctx->level.size.x + 1) + pos.x] = has_goal ? '*' : '$';
  return true;
}

static sok_ctx_walk_cbs_t
DRAW_CBS = {
  .on_size = draw_on_size,
  .on_home = draw_on_home,
  .on_wall = draw_on_wall,
  .on_goal = draw_on_goal,
  .on_box =  draw_on_box,
};

static void
draw(
  const sok_ctx_t * const ctx,
  const size_t level_num,
  const level_t * const level
) {
  // fill print buffer
  if (!sok_ctx_walk(ctx, &DRAW_CBS, NULL)) {
    die("Couldn't print level");
  }

  // print title, level, and console
  printf(
    "%s: %s (#%zu)\n" // set name, level name, and level number
    "%s\n"            // level
    "%zu%s> ",        // console
    level->pack, level->name, level_num,
    print_buf,
    ctx->num_moves, sok_ctx_is_done(ctx) ? " (won!)" : ""
  );
}

static void
solve_on_error(
  const char * const err
) {
  die("Error solving level: %s", err);
}

static void
print_moves(
  const sok_ctx_t * const ctx,
  const size_t skip_moves
) {
  printf("Solution (%zu moves): ", ctx->num_moves - skip_moves);
  for (size_t i = skip_moves; i < ctx->num_moves; i++) {
    if (ctx->moves[i].dir >= SOK_DIR_LAST) {
      die("invalid move: %u", ctx->moves[i].dir);
    }

    fputs(SOK_DIR_TO_STR(ctx->moves[i].dir), stdout);
  }
  printf("\n");
}

int main(int argc, char *argv[]) {
  size_t level_num = (argc > 1) ? atoi(argv[1]) : 0;
  const level_t *level = levels_get_level(level_num);

  // init context
  sok_ctx_t ctx;
  sok_ctx_init(&ctx, NULL);

  if (!sok_ctx_set_level(&ctx, level->data)) {
    die("Couldn't load level %zu", level_num);
  }

  bool done = false;
  while (!done) {
    // draw screen
    draw(&ctx, level_num, level);

    // read input, check for error
    const action_t action = get_action();

    switch (action.type) {
    case ACTION_QUIT:
      done = true;
      break;
    case ACTION_MOVE:
      if (!sok_ctx_move(&ctx, (sok_dir_t) action.data)) {
        warn("move %s failed", SOK_DIR_TO_STR((sok_dir_t) action.data));
      }

      break;
    case ACTION_UNDO:
      if (!sok_ctx_undo(&ctx)) {
        warn("undo failed");
      }

      break;
    case ACTION_NEXT:
      if (sok_ctx_is_done(&ctx)) {
        // advance level
        level_num++;
        level = levels_get_level(level_num);

        // load next level
        if (!sok_ctx_set_level(&ctx, level->data)) {
          die("Couldn't load level %zu", level_num);
        }
      } else {
        warn("cannot advance to next level");
      }

      break;
    case ACTION_WARP:
      level_num = action.data;
      level = levels_get_level(level_num);

      // load level
      if (!sok_ctx_set_level(&ctx, level->data)) {
        die("Couldn't load level %zu", level_num);
      }

      break;
    case ACTION_SOLVE:
      {
        // get current number of moves
        const size_t old_num_moves = ctx.num_moves;

        if (sok_solve(&ctx, solve_on_error)) {
          // found solution, print it
          print_moves(&ctx, old_num_moves);
        } else {
          warn("Couldn't solve level");
        }
      }

      break;
    default:
      // ignore
      break;
    }
  }

  // return success
  return EXIT_SUCCESS;
}