Deterministic ledger application

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ledger/src/main.fl

module main;

@imports
    :: root::commands
    :: root::model
    :: lib::std::fmt
    :: lib::std::os::arguments;

i32 main() {
    values, captureError := arguments::capture();
    if captureError != none {
        fmt::eprintln("ledger: cannot capture command-line arguments");
        return 3;
    }
    if values.len() < 2 {
        print_usage();
        return 2;
    }

    command := values[1].view();
    error result = none;
    if command == "create" and values.len() == 3 {
        result = commands::create(values[2].view());
    } else if command == "append" and values.len() == 4 {
        result = commands::append(values[2].view(), values[3].view());
    } else if command == "verify" and values.len() == 3 {
        result = commands::verify(values[2].view());
    } else if command == "list" and values.len() == 3 {
        result = commands::list(values[2].view());
    } else if command == "help" or command == "--help" or command == "-h" {
        print_usage();
        return 0;
    } else {
        result = model::LedgerError.Usage;
    }

    if result == none {
        return 0;
    }
    if result == model::LedgerError.Usage {
        print_usage();
        return 2;
    }
    if result == model::LedgerError.InvalidFormat or
        result == model::LedgerError.PayloadTooLarge {
        fmt::eprintln("ledger: invalid ledger format");
        return 4;
    }
    if result == model::LedgerError.IntegrityFailure {
        fmt::eprintln("ledger: integrity verification failed");
        return 5;
    }

    fmt::eprintln("ledger: operation failed");
    return 3;
}

void print_usage() {
    fmt::println("ledger - deterministic append-only SHA-256 chain");
    fmt::println("");
    fmt::println("usage:");
    fmt::println("  ledger create <file>");
    fmt::println("  ledger append <file> <payload>");
    fmt::println("  ledger verify <file>");
    fmt::println("  ledger list <file>");
}