Initial Go project structure, docs, build and CI

internal/config/config.go

@@ -0,0 +1,72 @@
+// Package config loads user settings from a JSON file in the OS-specific
+// user configuration directory. It knows nothing about rendering.
+package config
+
+import (
+	"encoding/json"
+	"errors"
+	"io/fs"
+	"os"
+	"path/filepath"
+
+	"github.com/andydixon/mapsize/internal/brand"
+)
+
+// Settings are user preferences. Zero values are never used directly; Load
+// starts from Defaults and overlays the file.
+type Settings struct {
+	Workers        string   `json:"workers"`         // conservative|balanced|aggressive|N
+	FollowSymlinks string   `json:"follow_symlinks"` // none|same-filesystem|all
+	OneFileSystem  bool     `json:"one_file_system"`
+	Units          string   `json:"units"`     // iec|si
+	SizeMode       string   `json:"size_mode"` // allocated|logical
+	Theme          string   `json:"theme"`
+	Mouse          bool     `json:"mouse"`
+	Excludes       []string `json:"excludes"`
+	// ExtensionColors maps an extension (without dot) to "#rrggbb".
+	ExtensionColors map[string]string `json:"extension_colors"`
+	// CategoryColors maps a category name to "#rrggbb".
+	CategoryColors map[string]string `json:"category_colors"`
+	// RefreshHz is the UI refresh rate while scanning.
+	RefreshHz int `json:"refresh_hz"`
+}
+
+// Defaults returns the built-in settings.
+func Defaults() Settings {
+	return Settings{
+		Workers: "balanced", FollowSymlinks: "none", Units: "iec", SizeMode: "allocated",
+		Theme: "default", Mouse: true, RefreshHz: 10,
+	}
+}
+
+// Path returns the config file location.
+func Path() (string, error) {
+	dir, err := os.UserConfigDir()
+	if err != nil {
+		return "", err
+	}
+	return filepath.Join(dir, brand.Name, "config.json"), nil
+}
+
+// Load reads the config file if present. A missing file is not an error.
+func Load() (Settings, error) {
+	s := Defaults()
+	p, err := Path()
+	if err != nil {
+		return s, nil
+	}
+	b, err := os.ReadFile(p)
+	if errors.Is(err, fs.ErrNotExist) {
+		return s, nil
+	}
+	if err != nil {
+		return s, err
+	}
+	if err := json.Unmarshal(b, &s); err != nil {
+		return Defaults(), err
+	}
+	if s.RefreshHz < 1 || s.RefreshHz > 60 {
+		s.RefreshHz = 10
+	}
+	return s, nil
+}