//! Server configuration. Uses plain struct defaults rather than wish's
//! functional `WithX` options — zig has struct defaults, so the option-fn
//! dance is unnecessary. Names still mirror wish for parity.
const Options = @This();

/// Listen address (host + port). `std.Io.net.IpAddress` gives us parsing and
/// validation for free — build it with `.parse("0.0.0.0", 2222)` or an
/// `.{ .ip4 = ... }` literal. Default is 0.0.0.0:2222 so examples run without
/// root.
address: IpAddress = .{ .ip4 = .{ .bytes = .{ 0, 0, 0, 0 }, .port = 2222 } },

/// Path to a host key on disk (any type libssh accepts). If null and
/// `host_key_pem` is also null, `serve` fails with `error.HostKeyRequired`.
host_key_path: ?[:0]const u8 = null,

/// In-memory PEM-encoded host key. Overrides `host_key_path` if both are set.
host_key_pem: ?[:0]const u8 = null,

/// Banner string sent before authentication.
banner: [:0]const u8 = "",

/// Server identification string. libssh default is used when null.
version: ?[:0]const u8 = null,

const std = @import("std");
const IpAddress = std.Io.net.IpAddress;
const Writer = std.Io.Writer;

/// Render the bind host (address *without* port) as a sentinel-terminated
/// string into `buf`, for libssh's `SSH_BIND_OPTIONS_BINDADDR`. Note that
/// `IpAddress.format` glues the port on (`a.b.c.d:port` / `[addr]:port`), so
/// we format host-only ourselves.
pub fn hostZ(self: Options, buf: []u8) ![:0]const u8 {
    switch (self.address) {
        .ip4 => |a| {
            const b = a.bytes;
            return std.fmt.bufPrintZ(buf, "{d}.{d}.{d}.{d}", .{ b[0], b[1], b[2], b[3] }) catch
                error.AddressTooLong;
        },
        .ip6 => {
            // Ip6Address.format emits "[addr]:port"; take the bracketed part.
            var tmp: [64]u8 = undefined;
            var w: Writer = .fixed(&tmp);
            self.address.format(&w) catch return error.AddressTooLong;
            const s = w.buffered();
            const start = (std.mem.indexOfScalar(u8, s, '[') orelse return error.AddressTooLong) + 1;
            const end = std.mem.indexOfScalar(u8, s, ']') orelse return error.AddressTooLong;
            return std.fmt.bufPrintZ(buf, "{s}", .{s[start..end]}) catch error.AddressTooLong;
        },
    }
}

/// Render the bind port as a sentinel-terminated string into `buf`, for
/// libssh's `SSH_BIND_OPTIONS_BINDPORT_STR`.
pub fn portZ(self: Options, buf: []u8) ![:0]const u8 {
    return std.fmt.bufPrintZ(buf, "{d}", .{self.address.getPort()});
}