var runtime = Module['Runtime'];
var malloc = Module['_malloc'];
var free = Module['_free'];
var Pointer_stringify = Module['Pointer_stringify'];
var OLM_ERROR = Module['_olm_error']();

/* The 'length' argument to Pointer_stringify doesn't work if the input includes
 * characters >= 128; we therefore need to add a NULL character to all of our
 * strings. This acts as a symbolic constant to help show what we're doing.
 */
var NULL_BYTE_PADDING_LENGTH = 1;

/* allocate a number of bytes of storage on the stack.
 *
 * If size_or_array is a Number, allocates that number of zero-initialised bytes.
 */
function stack(size_or_array) {
    return Module['allocate'](size_or_array, 'i8', Module['ALLOC_STACK']);
}

function array_from_string(string) {
    return Module['intArrayFromString'](string, true);
}

function random_stack(size) {
    var ptr = stack(size);
    var array = new Uint8Array(Module['HEAPU8'].buffer, ptr, size);
    get_random_values(array);
    return ptr;
}

function restore_stack(wrapped) {
    return function() {
        var sp = runtime.stackSave();
        try {
            return wrapped.apply(this, arguments);
        } finally {
            runtime.stackRestore(sp);
        }
    }
}

function Account() {
    var size = Module['_olm_account_size']();
    this.buf = malloc(size);
    this.ptr = Module['_olm_account'](this.buf);
}

function account_method(wrapped) {
    return function() {
        var result = wrapped.apply(this, arguments);
        if (result === OLM_ERROR) {
            var message = Pointer_stringify(
                Module['_olm_account_last_error'](arguments[0])
            );
            throw new Error("OLM." + message);
        }
        return result;
    }
}

Account.prototype['free'] = function() {
    Module['_olm_clear_account'](this.ptr);
    free(this.ptr);
}

Account.prototype['create'] = restore_stack(function() {
    var random_length = account_method(
        Module['_olm_create_account_random_length']
    )(this.ptr);
    var random = random_stack(random_length);
    account_method(Module['_olm_create_account'])(
        this.ptr, random, random_length
    );
});

Account.prototype['identity_keys'] = restore_stack(function() {
    var keys_length = account_method(
        Module['_olm_account_identity_keys_length']
    )(this.ptr);
    var keys = stack(keys_length + NULL_BYTE_PADDING_LENGTH);
    account_method(Module['_olm_account_identity_keys'])(
        this.ptr, keys, keys_length
    );
    return Pointer_stringify(keys);
});

Account.prototype['sign'] = restore_stack(function(message) {
    var signature_length = account_method(
        Module['_olm_account_signature_length']
    )(this.ptr);
    var message_array = array_from_string(message);
    var message_buffer = stack(message_array);
    var signature_buffer = stack(signature_length + NULL_BYTE_PADDING_LENGTH);
    account_method(Module['_olm_account_sign'])(
        this.ptr,
        message_buffer, message_array.length,
        signature_buffer, signature_length
    );
    return Pointer_stringify(signature_buffer);
});

Account.prototype['one_time_keys'] = restore_stack(function() {
    var keys_length = account_method(
        Module['_olm_account_one_time_keys_length']
    )(this.ptr);
    var keys = stack(keys_length + NULL_BYTE_PADDING_LENGTH);
    account_method(Module['_olm_account_one_time_keys'])(
        this.ptr, keys, keys_length
    );
    return Pointer_stringify(keys);
});

Account.prototype['mark_keys_as_published'] = restore_stack(function() {
    account_method(Module['_olm_account_mark_keys_as_published'])(this.ptr);
});

Account.prototype['max_number_of_one_time_keys'] = restore_stack(function() {
    return account_method(Module['_olm_account_max_number_of_one_time_keys'])(
        this.ptr
    );
});

Account.prototype['generate_one_time_keys'] = restore_stack(function(
    number_of_keys
) {
    var random_length = account_method(
        Module['_olm_account_generate_one_time_keys_random_length']
    )(this.ptr, number_of_keys);
    var random = random_stack(random_length);
    account_method(Module['_olm_account_generate_one_time_keys'])(
        this.ptr, number_of_keys, random, random_length
    );
});

Account.prototype['remove_one_time_keys'] = restore_stack(function(session) {
     account_method(Module['_olm_remove_one_time_keys'])(
        this.ptr, session.ptr
    );
});

Account.prototype['pickle'] = restore_stack(function(key) {
    var key_array = array_from_string(key);
    var pickle_length = account_method(
        Module['_olm_pickle_account_length']
    )(this.ptr);
    var key_buffer = stack(key_array);
    var pickle_buffer = stack(pickle_length + NULL_BYTE_PADDING_LENGTH);
    account_method(Module['_olm_pickle_account'])(
        this.ptr, key_buffer, key_array.length, pickle_buffer, pickle_length
    );
    return Pointer_stringify(pickle_buffer);
});

Account.prototype['unpickle'] = restore_stack(function(key, pickle) {
    var key_array = array_from_string(key);
    var key_buffer = stack(key_array);
    var pickle_array = array_from_string(pickle);
    var pickle_buffer = stack(pickle_array);
    account_method(Module['_olm_unpickle_account'])(
        this.ptr, key_buffer, key_array.length, pickle_buffer,
        pickle_array.length
    );
});

function Session() {
    var size = Module['_olm_session_size']();
    this.buf = malloc(size);
    this.ptr = Module['_olm_session'](this.buf);
}

function session_method(wrapped) {
    return function() {
        var result = wrapped.apply(this, arguments);
        if (result === OLM_ERROR) {
            var message = Pointer_stringify(
                Module['_olm_session_last_error'](arguments[0])
            );
            throw new Error("OLM." + message);
        }
        return result;
    }
}

Session.prototype['free'] = function() {
    Module['_olm_clear_session'](this.ptr);
    free(this.ptr);
}

Session.prototype['pickle'] = restore_stack(function(key) {
    var key_array = array_from_string(key);
    var pickle_length = session_method(
        Module['_olm_pickle_session_length']
    )(this.ptr);
    var key_buffer = stack(key_array);
    var pickle_buffer = stack(pickle_length + NULL_BYTE_PADDING_LENGTH);
    session_method(Module['_olm_pickle_session'])(
        this.ptr, key_buffer, key_array.length, pickle_buffer, pickle_length
    );
    return Pointer_stringify(pickle_buffer);
});

Session.prototype['unpickle'] = restore_stack(function(key, pickle) {
    var key_array = array_from_string(key);
    var key_buffer = stack(key_array);
    var pickle_array = array_from_string(pickle);
    var pickle_buffer = stack(pickle_array);
    session_method(Module['_olm_unpickle_session'])(
        this.ptr, key_buffer, key_array.length, pickle_buffer,
        pickle_array.length
    );
});

Session.prototype['create_outbound'] = restore_stack(function(
    account, their_identity_key, their_one_time_key
) {
    var random_length = session_method(
        Module['_olm_create_outbound_session_random_length']
    )(this.ptr);
    var random = random_stack(random_length);
    var identity_key_array = array_from_string(their_identity_key);
    var one_time_key_array = array_from_string(their_one_time_key);
    var identity_key_buffer = stack(identity_key_array);
    var one_time_key_buffer = stack(one_time_key_array);
    session_method(Module['_olm_create_outbound_session'])(
        this.ptr, account.ptr,
        identity_key_buffer, identity_key_array.length,
        one_time_key_buffer, one_time_key_array.length,
        random, random_length
    );
});

Session.prototype['create_inbound'] = restore_stack(function(
    account, one_time_key_message
) {
    var message_array = array_from_string(one_time_key_message);
    var message_buffer = stack(message_array);
    session_method(Module['_olm_create_inbound_session'])(
        this.ptr, account.ptr, message_buffer, message_array.length
    );
});

Session.prototype['create_inbound_from'] = restore_stack(function(
    account, identity_key, one_time_key_message
) {
    var identity_key_array = array_from_string(identity_key);
    var identity_key_buffer = stack(identity_key_array);
    var message_array = array_from_string(one_time_key_message);
    var message_buffer = stack(message_array);
    session_method(Module['_olm_create_inbound_session_from'])(
        this.ptr, account.ptr,
        identity_key_buffer, identity_key_array.length,
        message_buffer, message_array.length
    );
});

Session.prototype['session_id'] = restore_stack(function() {
    var id_length = session_method(Module['_olm_session_id_length'])(this.ptr);
    var id_buffer = stack(id_length + NULL_BYTE_PADDING_LENGTH);
    session_method(Module['_olm_session_id'])(
        this.ptr, id_buffer, id_length
    );
    return Pointer_stringify(id_buffer);
});

Session.prototype['has_received_message'] = function() {
    return session_method(Module['_olm_session_has_received_message'])(
        this.ptr
    ) ? true : false;
};


Session.prototype['matches_inbound'] = restore_stack(function(
    one_time_key_message
) {
    var message_array = array_from_string(one_time_key_message);
    var message_buffer = stack(message_array);
    return session_method(Module['_olm_matches_inbound_session'])(
        this.ptr, message_buffer, message_array.length
    ) ? true : false;
});

Session.prototype['matches_inbound_from'] = restore_stack(function(
    identity_key, one_time_key_message
) {
    var identity_key_array = array_from_string(identity_key);
    var identity_key_buffer = stack(identity_key_array);
    var message_array = array_from_string(one_time_key_message);
    var message_buffer = stack(message_array);
    return session_method(Module['_olm_matches_inbound_session_from'])(
        this.ptr,
        identity_key_buffer, identity_key_array.length,
        message_buffer, message_array.length
    ) ? true : false;
});

Session.prototype['encrypt'] = restore_stack(function(
    plaintext
) {
    var random_length = session_method(
        Module['_olm_encrypt_random_length']
    )(this.ptr);
    var message_type = session_method(
        Module['_olm_encrypt_message_type']
    )(this.ptr);
    var plaintext_array = array_from_string(plaintext);
    var message_length = session_method(
        Module['_olm_encrypt_message_length']
    )(this.ptr, plaintext_array.length);
    var random = random_stack(random_length);
    var plaintext_buffer = stack(plaintext_array);
    var message_buffer = stack(message_length + NULL_BYTE_PADDING_LENGTH);
    session_method(Module['_olm_encrypt'])(
        this.ptr,
        plaintext_buffer, plaintext_array.length,
        random, random_length,
        message_buffer, message_length
    );
    return {
        "type": message_type,
        "body": Pointer_stringify(message_buffer)
    };
});

Session.prototype['decrypt'] = restore_stack(function(
    message_type, message
) {
    var message_array = array_from_string(message);
    var message_buffer = stack(message_array);
    var max_plaintext_length = session_method(
        Module['_olm_decrypt_max_plaintext_length']
    )(this.ptr, message_type, message_buffer, message_array.length);
    // caculating the length destroys the input buffer.
    // So we copy the array to a new buffer
    var message_buffer = stack(message_array);
    var plaintext_buffer = stack(
        max_plaintext_length + NULL_BYTE_PADDING_LENGTH
    );
    var plaintext_length = session_method(Module["_olm_decrypt"])(
        this.ptr, message_type,
        message_buffer, message.length,
        plaintext_buffer, max_plaintext_length
    );

    // Pointer_stringify requires a null-terminated argument (the optional
    // 'len' argument doesn't work for UTF-8 data).
    Module['setValue'](
        plaintext_buffer+plaintext_length,
        0, "i8"
    );

    return Pointer_stringify(plaintext_buffer);
});

function Utility() {
    var size = Module['_olm_utility_size']();
    this.buf = malloc(size);
    this.ptr = Module['_olm_utility'](this.buf);
}

function utility_method(wrapped) {
    return function() {
        var result = wrapped.apply(this, arguments);
        if (result === OLM_ERROR) {
            var message = Pointer_stringify(
                Module['_olm_utility_last_error'](arguments[0])
            );
            throw new Error("OLM." + message);
        }
        return result;
    }
}

Utility.prototype['free'] = function() {
    Module['_olm_clear_utility'](this.ptr);
    free(this.ptr);
}

Utility.prototype['sha256'] = restore_stack(function(input) {
    var output_length = utility_method(Module['_olm_sha256_length'])(this.ptr);
    var input_array = array_from_string(input);
    var input_buffer = stack(input_array);
    var output_buffer = stack(output_length + NULL_BYTE_PADDING_LENGTH);
    utility_method(Module['_olm_sha2516'])(
        this.ptr,
        input_buffer, input_array.length(),
        output_buffer, output_length
    );
    return Pointer_stringify(output_buffer);
});

Utility.prototype['ed25519_verify'] = restore_stack(function(
    key, message, signature
) {
    var key_array = array_from_string(key);
    var key_buffer = stack(key_array);
    var message_array = array_from_string(message);
    var message_buffer = stack(message_array);
    var signature_array = array_from_string(signature);
    var signature_buffer = stack(signature_array);
    utility_method(Module['_olm_ed25519_verify'])(
        this.ptr,
        key_buffer, key_array.length,
        message_buffer, message_array.length,
        signature_buffer, signature_array.length
    );
});

olm_exports["Account"] = Account;
olm_exports["Session"] = Session;
olm_exports["Utility"] = Utility;

olm_exports['set_log_level'] = Module['_olm_set_log_level'];

olm_exports["get_library_version"] = restore_stack(function() {
    var buf = stack(3);
    Module['_olm_get_library_version'](buf, buf+1, buf+2);
    return [
        getValue(buf, 'i8'),
        getValue(buf+1, 'i8'),
        getValue(buf+2, 'i8'),
    ];
});
}();