#include "stdlib.fc";
#include "constants.fc";

const CHUNK_SIZE = 64;
const fee::receipt_value = 20000000;
const fee::storage = 10000000;



{-
  storage#_ active:Bool
            balance:Coins provider:MsgAddress
            merkle_hash:uint256 file_size:uint64 next_proof_byte:uint64
            rate_per_mb_day:Coins
            max_span:uint32 last_proof_time:uint32
            ^[client:MsgAddress torrent_hash:uint256] = Storage;
-}

(slice, int) begin_parse_special(cell c) asm "x{D739} s,";

int check_proof(int merkle_hash, int byte_to_proof, int file_size, cell file_dict_proof) {
    (slice cs, int special) = file_dict_proof.begin_parse_special();
    if (~ special) {
        return false;
    }
    if (cs~load_uint(8) != 3) { ;; Merkle proof
        return false;
    }
    if (cs~load_uint(256) != merkle_hash) {
        return false;
    }
    cell file_dict = cs~load_ref();
    int key_len = 0;
    while ((CHUNK_SIZE << key_len) < file_size) {
        key_len += 1;
    }
    (slice data, int found?) = file_dict.udict_get?(key_len, byte_to_proof / CHUNK_SIZE);
    if(found?) {
        return true;
    }
    return false;
}

() add_to_balance(int amount) impure inline_ref {
    var ds = get_data().begin_parse();
    var (active, balance, residue) = (ds~load_int(1), ds~load_grams(), ds);
    balance += amount;
    begin_cell()
            .store_int(active, 1)
            .store_coins(balance)
            .store_slice(residue)
            .end_cell().set_data();
}

(slice, int) get_client_data(ds) {
    ds = ds.preload_ref().begin_parse();
    return (ds~load_msg_addr(), ds~load_uint(256));
}

() recv_internal(int msg_value, cell in_msg_full, slice in_msg_body) impure {
    slice cs = in_msg_full.begin_parse();
    int flags = cs~load_uint(4);

    if (flags & 1) { ;; ignore all bounced messages
        return ();
    }
    slice sender_address = cs~load_msg_addr();

    if (in_msg_body.slice_empty?()) {
        return add_to_balance(msg_value);
    }
    int op = in_msg_body~load_uint(32);
    if (op == 0) {
        return add_to_balance(msg_value);
    }

    int query_id = in_msg_body~load_uint(64);

    if(op == op::offer_storage_contract) {
        add_to_balance(msg_value - 2 * fee::receipt_value);
        var (client, torrent_hash) = get_client_data(get_data().begin_parse());
        var msg = begin_cell()
                .store_uint(0x18, 6)
                .store_slice(client)
                .store_coins(fee::receipt_value)
                .store_uint(0, 1 + 4 + 4 + 64 + 32 + 1 + 1)
                .store_uint(op::contract_deployed, 32)
                .store_uint(query_id, 64)
                .store_uint(torrent_hash, 256)
                .end_cell();
        send_raw_message(msg, 0);
    }

    if (op == op::accept_storage_contract) {
        var ds = get_data().begin_parse();
        (int active, int balance, slice provider, slice rest) =
                (ds~load_int(1), ds~load_coins(), ds~load_msg_addr(), ds);
        throw_unless(error::contract_already_active, ~ active);
        throw_unless(error::unauthorized, equal_slice_bits(sender_address, provider));
        begin_cell()
                .store_int(true, 1)
                .store_coins(balance)
                .store_slice(provider)
                .store_slice(rest)
                .end_cell().set_data();
        var (client, torrent_hash) = get_client_data(rest);
        var msg = begin_cell()
                .store_uint(0x18, 6)
                .store_slice(client)
                .store_coins(fee::receipt_value)
                .store_uint(0, 1 + 4 + 4 + 64 + 32 + 1 + 1)
                .store_uint(op::storage_contract_confirmed, 32)
                .store_uint(cur_lt(), 64)
                .store_uint(torrent_hash, 256)
                .end_cell();
        send_raw_message(msg, 0);
    }

    if (op == op::close_contract) {
        var ds = get_data().begin_parse();
        (int active, int balance, slice provider, slice rest) =
                (ds~load_int(1), ds~load_coins(), ds~load_msg_addr(), ds);
        var (client, torrent_hash) = get_client_data(rest);
        throw_unless(error::unauthorized, equal_slice_bits(sender_address, provider) | equal_slice_bits(sender_address, client));
        var client_msg = begin_cell()
                .store_uint(0x18, 6)
                .store_slice(client)
                .store_coins(balance)
                .store_uint(0, 1 + 4 + 4 + 64 + 32 + 1 + 1)
                .store_uint(op::storage_contract_terminated, 32)
                .store_uint(cur_lt(), 64)
                .store_uint(torrent_hash, 256)
                .end_cell();
        if(~ active) {
            return send_raw_message(client_msg, 128 + 32);
        }
        send_raw_message(client_msg, 64);
        var provider_msg = begin_cell()
                .store_uint(0x18, 6)
                .store_slice(provider)
                .store_coins(0)
                .store_uint(0, 1 + 4 + 4 + 64 + 32 + 1 + 1)
                .store_uint(op::storage_contract_terminated, 32)
                .store_uint(cur_lt(), 64)
                .store_uint(torrent_hash, 256)
                .end_cell();
        return send_raw_message(provider_msg, 128 + 32);
    }

    if (op == op::withdraw) {
        var ds = get_data().begin_parse();
        (int active, int balance, slice provider) = (ds~load_int(1), ds~load_coins(), ds~load_msg_addr());
        throw_unless(error::contract_not_active, active);
        throw_unless(error::unauthorized, equal_slice_bits(sender_address, provider));
        if(balance > 0) {
            raw_reserve(balance + fee::storage, 2);
        }
        var msg = begin_cell()
                .store_uint(0x18, 6)
                .store_slice(provider)
                .store_coins(fee::receipt_value)
                .store_uint(0, 1 + 4 + 4 + 64 + 32 + 1 + 1)
                .store_uint(op::reward_withdrawal, 32)
                .store_uint(query_id, 64)
                .end_cell();
        send_raw_message(msg, 128 + 32);
    }

    if (op == op::proof_storage) {
        cell file_dict_proof = in_msg_body~load_ref();
        var ds = get_data().begin_parse();
        var (active,
                balance,
                provider,
                merkle_hash,
                file_size,
                next_proof,
                rate_per_mb_day,
                max_span,
                last_proof_time,
                client_data) = (ds~load_int(1),
                ds~load_coins(),
                ds~load_msg_addr(),
                ds~load_uint(256),
                ds~load_uint(64),
                ds~load_uint(64),
                ds~load_coins(),
                ds~load_uint(32),
                ds~load_uint(32),
                ds~load_ref());
        throw_unless(error::contract_not_active, active);
        throw_unless(error::unauthorized, equal_slice_bits(sender_address, provider));
        throw_unless(error::wrong_proof, check_proof(merkle_hash, next_proof, file_size, file_dict_proof));
        next_proof = rand(file_size);
        int actual_span = min(now() - last_proof_time, max_span);
        int bounty = muldiv(file_size * rate_per_mb_day, actual_span, 24 * 60 * 60 * 1024 * 1024);
        balance = max(0, balance - bounty);
        last_proof_time = now();
        begin_cell()
                .store_int(true, 1)
                .store_coins(balance)
                .store_slice(provider)
                .store_uint(merkle_hash, 256)
                .store_uint(file_size, 64)
                .store_uint(next_proof, 64)
                .store_coins(rate_per_mb_day)
                .store_uint(max_span, 32)
                .store_uint(last_proof_time, 32)
                .store_ref(client_data)
                .end_cell().set_data();

        ;; Send remaining balance back
        cell msg = begin_cell()
                .store_uint(0x18, 6)
                .store_slice(sender_address)
                .store_uint(0, 4 + 1 + 4 + 4 + 64 + 32 + 1 + 1)
                .end_cell();
        send_raw_message(msg, 64 + 2);
    }
}

_ get_storage_contract_data() method_id {
    var ds = get_data().begin_parse();
    var (active,
            balance,
            provider,
            merkle_hash,
            file_size,
            next_proof,
            rate_per_mb_day,
            max_span,
            last_proof_time,
            rest) = (ds~load_int(1),
            ds~load_coins(),
            ds~load_msg_addr(),
            ds~load_uint(256),
            ds~load_uint(64),
            ds~load_uint(64),
            ds~load_coins(),
            ds~load_uint(32),
            ds~load_uint(32),
            ds);
    var (client, torrent_hash) = get_client_data(rest);
    return (active, balance, provider, merkle_hash, file_size,
            next_proof, rate_per_mb_day, max_span, last_proof_time,
            client, torrent_hash);
}

_ get_torrent_hash() method_id {
    var (active, balance, provider, merkle_hash, file_size,
            next_proof, rate_per_mb_day, max_span, last_proof_time,
            client, torrent_hash) = get_storage_contract_data();
    return torrent_hash;
}

_ is_active() method_id {
    return get_data().begin_parse().preload_int(1);
}

;; next_proof, last_proof_time, max_span
_ get_next_proof_info() method_id {
    var (active, balance, provider, merkle_hash, file_size,
            next_proof, rate_per_mb_day, max_span, last_proof_time,
            client, torrent_hash) = get_storage_contract_data();
    return (next_proof, last_proof_time, max_span);
}