#pragma once

#include "fat12.h"

#include <stdint.h>
#include <stddef.h>
#include <functional>
#include <vector>
#include <string>

namespace esphome {
namespace grub_boot_switch {

constexpr uint32_t SECTOR_COUNT = 128;
constexpr uint32_t SECTOR_SIZE = 512;
constexpr uint32_t SECTORS_PER_CLUSTER = 1;
constexpr uint32_t RESERVED_SECTORS = 1;
constexpr uint32_t FAT_COPIES = 2;
constexpr uint32_t ROOT_ENTRIES = 512;
constexpr uint32_t ROOT_ENTRY_LENGTH = 32;
constexpr uint32_t FILEDATA_START_CLUSTER = 3;
constexpr uint32_t DATA_REGION_SECTOR =
    RESERVED_SECTORS + FAT_COPIES + (ROOT_ENTRIES * ROOT_ENTRY_LENGTH) / SECTOR_SIZE;
constexpr uint32_t FILEDATA_START_SECTOR =
    DATA_REGION_SECTOR + (FILEDATA_START_CLUSTER - 2) * SECTORS_PER_CLUSTER;

using FileReadCallback = std::function<void(uint8_t *output)>;

struct VirtualFile {
  std::string long_name;
  FatDirEntry dir;
  FileReadCallback read;
};

class MscDisk {
 public:
  MscDisk();

  // Volume serial baked into the FAT boot sector.
  // Default 0x55AA6922 matches the upstream stecman/hw-boot-selection firmware
  // so existing GRUB hooks (search --fs-uuid 55AA-6922) keep working unchanged.
  void set_volume_serial(uint32_t serial) { volume_serial_ = serial; }
  void set_volume_label(const char *label);  // 11 chars, space-padded

  // Date stamped on every directory entry. GRUB 2.06 rejects 0-valued dates.
  void set_file_date(uint16_t year, uint8_t month, uint8_t day);

  // Register a file. Short name must be 8.3 with space padding handled by caller
  // (use add_file() helper below for typical cases). size is the file's logical
  // size in bytes; content_cb is called once per host read of the file's sector.
  void add_file(const std::string &long_name, const std::string &short_name,
                const std::string &short_ext, uint32_t size, FileReadCallback content_cb);

  // Synthesise a single 512-byte sector for LBA `lba` into `out`.
  // out is zeroed first. Returns 0 on success.
  int read_lba(uint32_t lba, uint8_t *out);

  uint32_t sector_count() const { return SECTOR_COUNT; }
  uint32_t sector_size() const { return SECTOR_SIZE; }

 protected:
  void write_boot_sector(uint8_t *out);
  void write_fat_sector(uint8_t *out);
  void write_dir_sector(uint8_t *out);

  uint32_t volume_serial_ = 0x55AA6922u;
  char volume_label_[11] = {'S', 'W', 'I', 'T', 'C', 'H', ' ', ' ', ' ', ' ', ' '};
  uint16_t file_date_ = 0;
  std::vector<VirtualFile> files_;
};

}  // namespace grub_boot_switch
}  // namespace esphome