Ledger storage

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module storage;

@imports
    :: root::codec
    :: root::model
    :: lib::std::containers::collections
    :: lib::std::encoding::hex
    :: lib::std::io::file
    :: lib::std::io::filesystem;

export error create(stringv path) {
    options := build file::OpenOptions {
        self.write = true;
        self.createNew = true;
    };
    output, openError := file::File::open(path, options);
    if openError != none {
        return openError;
    }

    error result = output.writeAll(codec::FILE_HEADER.cast<[]const u8>);
    if result == none {
        result = output.flush();
    }
    closeError := output.close();
    if result == none {
        result = closeError;
    }
    if result != none {
        error _ = filesystem::remove_file(path);
    }
    return result;
}

export (collections::Array<model::Block>, error) load(stringv path) {
    contents, readError := filesystem::read_file(path);
    if readError != none {
        return (collections::Array<model::Block>::init(), readError);
    }
    return codec::parse(contents.view());
}

export (u64, string, error) append(stringv path, stringv payload) {
    blocks, loadError := load(path);
    if loadError != none {
        return (none, none, loadError);
    }

    u64 index = blocks.len().cast<u64>;
    [32]u8 previous = none;
    if !blocks.empty() {
        values := blocks.view();
        previous = model::copy_digest(values[values.len() - 1].hash());
    }

    record, digest, encodeError := codec::encode_block(
        index,
        previous[:],
        payload
    );
    if encodeError != none {
        return (none, none, encodeError);
    }

    output, openError := file::File::open(path, file::OpenOptions::appendOnly());
    if openError != none {
        return (none, none, openError);
    }
    error result = output.writeAll(record.bytes());
    if result == none {
        result = output.flush();
    }
    closeError := output.close();
    if result == none {
        result = closeError;
    }
    if result != none {
        return (none, none, result);
    }

    digestText, hexError := hex::encode_bytes(digest[:]);
    return (index, digestText, hexError);
}