git.giacomolli.uk - onechat/blob - config.go

   1 package main
   2
   3 import (
   4         "bytes"
   5         "encoding/json"
   6         "errors"
   7         "fmt"
   8         "io"
   9         "os"
  10         "path/filepath"
  11 )
  12
  13 const (
  14         // endpointChatGPT names the ChatGPT backend with the subscription login.
  15         endpointChatGPT = "chatgpt"
  16
  17         // endpointAPI names the OpenAI API with an API key.
  18         endpointAPI = "api"
  19 )
  20
  21 // Config holds the settings of config.json in the data directory.
  22 type Config struct {
  23         Endpoint  string      `json:"endpoint"`
  24         Compactor ModelConfig `json:"compactor"`
  25 }
  26
  27 // ModelConfig names a model and its reasoning effort.
  28 type ModelConfig struct {
  29         Model  string `json:"model"`
  30         Effort string `json:"effort"`
  31 }
  32
  33 // defaultConfig returns the settings that apply when config.json does not
  34 // set them.
  35 func defaultConfig() Config {
  36         return Config{
  37                 Endpoint: endpointChatGPT,
  38                 Compactor: ModelConfig{
  39                         Model:  "gpt-6-luna",
  40                         Effort: "high",
  41                 },
  42         }
  43 }
  44
  45 // loadConfig reads config.json in dir over the defaults. A missing file gives
  46 // the defaults. An unknown field is an error, so a typo does not become a
  47 // silent default.
  48 func loadConfig(dir string) (Config, error) {
  49         config := defaultConfig()
  50         data, err := os.ReadFile(filepath.Join(dir, "config.json"))
  51         if errors.Is(err, os.ErrNotExist) {
  52                 return config, nil
  53         }
  54
  55         if err != nil {
  56                 return Config{}, fmt.Errorf("read config: %w", err)
  57         }
  58
  59         decoder := json.NewDecoder(bytes.NewReader(data))
  60         decoder.DisallowUnknownFields()
  61         err = decoder.Decode(&config)
  62         if err == nil && !errors.Is(decoder.Decode(&struct{}{}), io.EOF) {
  63                 err = errors.New("data after the JSON object")
  64         }
  65
  66         if err == nil {
  67                 err = config.validate()
  68         }
  69
  70         if err != nil {
  71                 return Config{}, fmt.Errorf("config.json: %w", err)
  72         }
  73
  74         return config, nil
  75 }
  76
  77 // validate makes sure that each setting has a valid value.
  78 func (c Config) validate() error {
  79         if c.Endpoint != endpointChatGPT && c.Endpoint != endpointAPI {
  80                 return fmt.Errorf("endpoint %q is not %q or %q", c.Endpoint, endpointChatGPT, endpointAPI)
  81         }
  82
  83         if c.Compactor.Model == "" || c.Compactor.Effort == "" {
  84                 return errors.New("compactor needs a model and an effort")
  85         }
  86
  87         return nil
  88 }
  89
  90 // dataDir returns the data directory and creates it with mode 0700 when it
  91 // does not exist. It is ONECHAT_DIR when that is set. Otherwise it is
  92 // $XDG_DATA_HOME/onechat when XDG_DATA_HOME is an absolute path, or else
  93 // ~/.local/share/onechat.
  94 func dataDir() (string, error) {
  95         dir := os.Getenv("ONECHAT_DIR")
  96         if dir == "" {
  97                 var err error
  98                 dir, err = defaultDataDir()
  99                 if err != nil {
 100                         return "", err
 101                 }
 102         }
 103
 104         err := os.MkdirAll(dir, 0o700)
 105         if err != nil {
 106                 return "", fmt.Errorf("create data directory: %w", err)
 107         }
 108
 109         return dir, nil
 110 }
 111
 112 // defaultDataDir returns the data directory for an unset ONECHAT_DIR. The XDG
 113 // specification says to ignore a relative XDG_DATA_HOME.
 114 func defaultDataDir() (string, error) {
 115         xdg := os.Getenv("XDG_DATA_HOME")
 116         if filepath.IsAbs(xdg) {
 117                 return filepath.Join(xdg, "onechat"), nil
 118         }
 119
 120         home, err := os.UserHomeDir()
 121         if err != nil {
 122                 return "", fmt.Errorf("find data directory: set ONECHAT_DIR: %w", err)
 123         }
 124
 125         return filepath.Join(home, ".local", "share", "onechat"), nil
 126 }