#!/usr/bin/env python3
# Writes docs/options.md from the option catalog in internal/dhcp4/catalog.go
# (the options by name, and the reserved codes). Run from the repository
# root after changing the catalog:
#
#   python3 scripts/optionsdoc.py
import re

src = open("internal/dhcp4/catalog.go").read()
rows = re.findall(r'\{Code: (\d+), Name: "([^"]+)", Type: (\w+), Help: "((?:[^"\\]|\\.)*)"', src)
types = {"TypeIP": "ip", "TypeIPs": "ips", "TypeString": "string", "TypeU8": "uint8", "TypeU16": "uint16", "TypeU32": "uint32",
         "TypeI32": "int32", "TypeBool": "bool", "TypeDomains": "domains", "TypeRoutes": "routes", "TypeHex": "hex"}
reserved = re.findall(r'^\t(\d+): +"([^"]+)",', src, re.M)

out = """# DHCP options

Options are set by name, or by number with a type. Set them in the
settings (every subnet), on a subnet, or on a reservation; the most
specific wins ([subnets.md](subnets.md#options)).

```sh
steward settings set --option domain-name-servers=10.0.10.2,10.0.10.3
steward subnet update office --option routers=10.0.10.1 --unset-option ntp-servers
steward reservation update nas --option 224:string=hello   # an option Steward doesn't know
```

`steward option list` prints the list below; the web UI offers it in each
options editor. (This page is written by scripts/optionsdoc.py from the
catalog in internal/dhcp4/catalog.go.)

## Options by name

| Code | Name | Type | What |
|---:|---|---|---|
"""
for code, name, typ, help_ in rows:
    help_ = help_.replace('\\"', '"').replace("|", "\\|")
    out += f"| {code} | `{name}` | {types[typ]} | {help_} |\n"
out += """
The names are Kea's, so a Kea configuration's options carry over.

## Value types

| Type | How to write it | Example |
|---|---|---|
| ip | an IPv4 address | `10.0.10.255` |
| ips | IPv4 addresses, separated by commas or spaces, in order of preference | `10.0.10.2, 10.0.10.3` |
| string | text, as it is | `lan` |
| uint8, uint16, uint32 | a whole number | `1500` |
| int32 | a whole number, maybe negative | `-3600` |
| bool | `true` or `false` (`yes`/`no`, `on`/`off`, `1`/`0` work too) | `false` |
| domains | domain names, separated by commas or spaces; sent in DNS wire format (RFC 3397) | `lan, home.arpa` |
| routes | `DESTINATION/LENGTH via ROUTER`, separated by commas (Kea's `DEST - ROUTER` works too); RFC 3442 | `10.20.0.0/16 via 10.0.10.1, 0.0.0.0/0 via 10.0.10.1` |
| hex | bytes in hex, with or without colons | `01:02:0a` |

Values are checked when they are set, and stored in a canonical form:
`10.0.10.2,10.0.10.3` becomes `10.0.10.2, 10.0.10.3`.

Clients that use `classless-static-route` ignore `routers`, so give the
default route in it as well (`0.0.0.0/0 via ROUTER`).

## Options by number

An option the list doesn't have is set by its number and type,
`CODE:TYPE=VALUE`; without a type the value is hex:

```sh
steward subnet update office --option 224:string=hello --option 225=01:02
```

In the API, give `{"option": "224", "type": "string", "value": "hello"}`.

## Options Steward sets itself

These can't be set; Steward fills them in (`option_reserved` if you try):

| Code | Why |
|---:|---|
"""
for code, why in reserved:
    out += f"| {code} | {why} |\n"
open("docs/options.md", "w").write(out)
print("wrote docs/options.md")