// Copyright (c) 2018, The Monero Project
// All rights reserved.
//
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// permitted provided that the following conditions are met:
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//    conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright notice, this list
//    of conditions and the following disclaimer in the documentation and/or other
//    materials provided with the distribution.
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//    used to endorse or promote products derived from this software without specific
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//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY
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#pragma once

#include <iosfwd>
#include <list>
#include <memory>
#include <utility>
#include <vector>

#include "common/expect.h"
#include "crypto/crypto.h"
#include "db/account.h"
#include "db/data.h"
#include "fwd.h"
#include "lmdb/transaction.h"
#include "lmdb/key_stream.h"
#include "lmdb/value_stream.h"

namespace cryptonote { class checkpoints; }
namespace lws
{
namespace db
{
  namespace cursor
  {
    MONERO_CURSOR(accounts);
    MONERO_CURSOR(outputs);
    MONERO_CURSOR(spends);
    MONERO_CURSOR(images);
    MONERO_CURSOR(requests);
    MONERO_CURSOR(subaddress_ranges);
    MONERO_CURSOR(subaddress_indexes);

    MONERO_CURSOR(blocks);
    MONERO_CURSOR(pow);
    MONERO_CURSOR(accounts_by_address);
    MONERO_CURSOR(accounts_by_height);
  
    MONERO_CURSOR(webhooks);
    MONERO_CURSOR(events);
  }

  struct storage_internal;
  struct reader_internal
  {
    cursor::blocks blocks_cur;
    cursor::accounts_by_address accounts_ba_cur;
    cursor::accounts_by_height accounts_bh_cur;
  };

  struct pow_window
  {
    std::vector<std::uint64_t> pow_timestamps; //!< for pow calculation
    std::vector<block_difficulty::unsigned_int> cumulative_diffs;
    std::vector<std::uint64_t> median_timestamps; //!< for timestamp check
  };

  //! Wrapper for LMDB read access to on-disk storage of light-weight server data.
  class storage_reader
  {
    std::shared_ptr<storage_internal> db;
    lmdb::read_txn txn;
    reader_internal curs;

  public:
    storage_reader(std::shared_ptr<storage_internal> db, lmdb::read_txn txn) noexcept
      : db(std::move(db)), txn(std::move(txn)), curs{}
    {}

    storage_reader(storage_reader&&) = default;
    storage_reader(storage_reader const&) = delete;

    ~storage_reader() noexcept;

    storage_reader& operator=(storage_reader&&) = default;
    storage_reader& operator=(storage_reader const&) = delete;

    //! \return Last known block.
    expect<block_info> get_last_block() noexcept;

    //! \return Last known pow block.
    expect<block_pow> get_last_pow_block() noexcept;

    //! \return "Our" block hash at `height`.
    expect<crypto::hash> get_block_hash(const block_id height) noexcept;

    //! \return List for `GetHashesFast` to sync blockchain with daemon.
    expect<std::list<crypto::hash>> get_chain_sync();

    //! \return List for GetBlocksFast` to sync blockchain+pow with daemon
    expect<std::list<crypto::hash>> get_pow_sync();

    //! \return Objects for use with cryptonote::next_difficulty and median timestamp check
    expect<pow_window> get_pow_window(block_id last);

    //! \return All registered `account`s.
    expect<lmdb::key_stream<account_status, account, cursor::close_accounts>>
      get_accounts(cursor::accounts cur = nullptr) noexcept;

    //! \return All `account`s currently in `status` or `lmdb::error(MDB_NOT_FOUND)`.
    expect<lmdb::value_stream<account, cursor::close_accounts>>
      get_accounts(account_status status, cursor::accounts cur = nullptr) noexcept;

    //! \return Info for account `id` iff it has `status`.
    expect<account> get_account(const account_status status, const account_id id) noexcept;

    //! \return Info related to `address`.
    expect<std::pair<account_status, account>>
      get_account(account_address const& address) noexcept;

    //! \return All outputs received by `id`.
    expect<lmdb::value_stream<output, cursor::close_outputs>>
      get_outputs(account_id id, cursor::outputs cur = nullptr) noexcept;

    //! \return All potential spends by `id`.
    expect<lmdb::value_stream<spend, cursor::close_spends>>
      get_spends(account_id id, cursor::spends cur = nullptr) noexcept;

    //! \return All key images associated with `id`.
    expect<lmdb::value_stream<db::key_image, cursor::close_images>>
      get_images(output_id id, cursor::images cur = nullptr) noexcept;

    //! \return All `request_info`s.
    expect<lmdb::key_stream<request, request_info, cursor::close_requests>>
      get_requests(cursor::requests cur = nullptr) noexcept;

    //! \return A specific request from `address` of `type`.
    expect<request_info>
      get_request(request type, account_address const& address, cursor::requests cur = nullptr) noexcept;

    //! \return All subaddresses activated for account `id`.
    expect<std::vector<subaddress_dict>> get_subaddresses(account_id id, cursor::subaddress_ranges cur = nullptr) noexcept;

    //! \return A specific subaddress index
    expect<address_index>
      find_subaddress(account_id id, crypto::public_key const& spend_public, cursor::subaddress_indexes& cur) noexcept;

    //! \return All webhook values associated with user `key` and `payment_id`.
    expect<std::vector<webhook_value>>
      find_webhook(webhook_key const& key, crypto::hash8 const& payment_id, cursor::webhooks cur = nullptr);

    //! \return All webhooks in the DB
    expect<std::vector<std::pair<webhook_key, std::vector<webhook_value>>>>
      get_webhooks(cursor::webhooks cur = nullptr);

    //! Dump the contents of the database in JSON format to `out`.
    expect<void> json_debug(std::ostream& out, bool show_keys);

    //! \return Read txn that can be re-used via `storage::start_read`.
    lmdb::suspended_txn finish_read() noexcept;
  };

  //! Wrapper for LMDB on-disk storage of light-weight server data.
  class storage
  {
    std::shared_ptr<storage_internal> db;

    storage(std::shared_ptr<storage_internal> db) noexcept
      : db(std::move(db))
    {}

  public:

    //! \return A single instance of compiled-in checkpoints for lws
    static cryptonote::checkpoints const& get_checkpoints();

    //! \return Last hard-coded block checkpoint
    static block_info get_last_checkpoint();

    /*!
      Open a light_wallet_server LDMB database.

      \param path Directory for LMDB storage
      \param create_queue_max Maximum number of create account requests allowed.

      \throw std::system_error on any LMDB error (all treated as fatal).
      \throw std::bad_alloc If `std::shared_ptr` fails to allocate.

      \return A ready light-wallet server database.
    */
    static storage open(const char* path, unsigned create_queue_max);

    storage(storage&&) = default;
    storage(storage const&) = delete;

    ~storage() noexcept;

    storage& operator=(storage&&) = default;
    storage& operator=(storage const&) = delete;

    //! \return A copy of the LMDB environment, but not reusable txn/cursors.
    storage clone() const noexcept;

    //! Rollback chain and accounts to `height`.
    expect<void> rollback(block_id height);

    /*!
      Sync the local blockchain with a remote version. Pops user txes if reorg
      detected.

      \param height The height of the element in `hashes`
      \param hashes List of blockchain hashes starting at `height`.

      \return True if the local blockchain is correctly synced.
    */
    expect<void> sync_chain(block_id height, epee::span<const crypto::hash> hashes);

    expect<void> sync_pow(block_id height, epee::span<const crypto::hash> hashes, epee::span<const pow_sync> pow);

    //! Bump the last access time of `address` to the current time.
    expect<void> update_access_time(account_address const& address) noexcept;

    //! Change state of `address` to `status`. \return Updated `addresses`.
    expect<std::vector<account_address>>
      change_status(account_status status, epee::span<const account_address> addresses);


    //! Add an account, for immediate inclusion in the active list.
    expect<void> add_account(account_address const& address, crypto::secret_key const& key, account_flags flags = account_flags::default_account) noexcept;

    //! Reset `addresses` to `height` for scanning.
    expect<std::vector<account_address>>
      rescan(block_id height, epee::span<const account_address> addresses);

    //! Add an account for later approval. For use with the login endpoint.
    expect<std::vector<webhook_new_account>> creation_request(account_address const& address, crypto::secret_key const& key, account_flags flags) noexcept;

    /*!
      Request lock height of an existing account. No effect if the `start_height`
      is already older.
    */
    expect<void> import_request(account_address const& address, block_id height) noexcept;

    //! Accept requests by `addresses` of type `req`. \return Accepted addresses.
    expect<std::vector<account_address>>
      accept_requests(request req, epee::span<const account_address> addresses);

    //! Reject requests by `addresses` of type `req`. \return Rejected addresses.
    expect<std::vector<account_address>>
      reject_requests(request req, epee::span<const account_address> addresses);

    /*!
      Updates the status of user accounts, even if inactive or hidden. Duplicate
      receives or spends provided in `accts` are silently ignored. If a gap in
      `height` vs the stored account record is detected, the entire update will
      fail.

      \param height The first hash in `chain` is at this height.
      \param chain List of block hashes that `accts` were scanned against.
      \param accts Updated to `height + chain.size()` scan height.

      \return True iff LMDB successfully committed the update.
    */
    expect<std::pair<std::size_t, std::vector<webhook_tx_confirmation>>>
      update(block_id height, epee::span<const crypto::hash> chain, epee::span<const lws::account> accts, epee::span<const pow_sync> pow);

    /*!
      Adds subaddresses to an account. Upon success, an account will
      immediately begin tracking them in the scanner.
      
      \param id of the account to associate new indexes
      \param addresss of the account (needed to generate subaddress publc key)
      \param view_key of the account (needed to generate subaddress public key)
      \param subaddrs Range of subaddress indexes that need to be added to the
        database. Indexes _may_ overlap with existing indexes.
      \param max_subaddresses The maximum number of subaddresses allowed per
        account.

      \return The new ranges of subaddress indexes added to the database
        (whereas `subaddrs` may overlap with existing indexes).
      */
    expect<std::vector<subaddress_dict>>
      upsert_subaddresses(account_id id, const account_address& address, const crypto::secret_key& view_key, std::vector<subaddress_dict> subaddrs, std::uint32_t max_subaddresses);

    /*!
      Add webhook to be tracked in the database. The webhook will "call"
      the specified URL with JSON/msgpack information when the event occurs.
     
      \param type The webhook event type to be tracked by the DB.
      \param address is required for `type == tx_confirmation`, and is not
        not needed for all other types.
      \param event Additional information for the webhook. A valid "http"
        or "https" URL must be provided (or else error). All other information
        is optional.
     */
    expect<void> add_webhook(webhook_type type, const boost::optional<account_address>& address, const webhook_value& event);

    /*! Delete all webhooks associated with every value in `addresses`. This is
      likely only valid for `tx_confirmation` event types. */
    expect<void> clear_webhooks(epee::span<const account_address> addressses);

    //! Delete all webhooks associated with every value in `ids`
    expect<void> clear_webhooks(std::vector<boost::uuids::uuid> ids);

    //! `txn` must have come from a previous call on the same thread.
    expect<storage_reader> start_read(lmdb::suspended_txn txn = nullptr) const;
  };
} // db
} // lws