| 🛟 Updated. 28d5985 k33g 18h ago | 1 | package theme |
| 2 | |
| 3 | import ( |
| 4 | "embed" |
| 5 | "errors" |
| 6 | "fmt" |
| 7 | "io/fs" |
| 8 | "os" |
| 9 | "path/filepath" |
| 10 | "sort" |
| 11 | "strings" |
| 12 | |
| 13 | "github.com/BurntSushi/toml" |
| 14 | "github.com/gdamore/tcell/v2" |
| 15 | ) |
| 16 | |
| 17 | //go:embed themes/*.toml |
| 18 | var embeddedThemes embed.FS |
| 19 | |
| 20 | // embeddedDir is where the built-in theme files live inside the binary. |
| 21 | const embeddedDir = "themes" |
| 22 | |
| 23 | // DefaultName is the theme used when the user has not chosen one. |
| 24 | const DefaultName = "turbo-classic" |
| 25 | |
| 26 | // ErrNotFound is returned by Load when no theme of that name exists, either in |
| 27 | // the user's directory or among the embedded ones. |
| 28 | var ErrNotFound = errors.New("theme: not found") |
| 29 | |
| 30 | // maxInheritDepth stops a chain of "inherits" from looping forever. |
| 31 | const maxInheritDepth = 16 |
| 32 | |
| 33 | // retiredNames maps a name a shipped theme used to answer to onto the name it |
| 34 | // answers to now. |
| 35 | // |
| 36 | // A theme's name is not this project's to change: it is what somebody wrote in |
| 37 | // a settings file their whole team shares, and what they typed after -theme. |
| 38 | // When "monochrome" gained a light counterpart, keeping the pair symmetric was |
| 39 | // worth a rename and breaking those files was not, so the old name still |
| 40 | // loads. |
| 41 | // |
| 42 | // An alias is deliberately *not* listed by Available, so the theme dialog and |
| 43 | // -list-themes show each theme once, under the name it has now. What it costs |
| 44 | // is that a name here can never be reused for a different theme, which is the |
| 45 | // same promise the rename was made to keep. |
| 46 | var retiredNames = map[string]string{ |
| 47 | "monochrome": "monochrome-dark", |
| 48 | } |
| 49 | |
| 50 | // file is the on-disk shape of a theme. |
| 51 | type file struct { |
| 52 | Name string `toml:"name"` |
| 53 | Description string `toml:"description"` |
| 54 | Inherits string `toml:"inherits"` |
| 55 | Colors map[string]Entry `toml:"colors"` |
| 56 | } |
| 57 | |
| 58 | // Load returns the theme called name, looking in userDir before the themes |
| 59 | // embedded in the binary. |
| 60 | // |
| 61 | // A file in userDir wins over an embedded theme of the same name, so a shipped |
| 62 | // theme can be overridden without being replaced. Pass "" for userDir to offer |
| 63 | // the embedded themes alone, which is what a system with no configuration |
| 64 | // directory gets. |
| 65 | // |
| 66 | // th, err := theme.Load("turbo-classic", p.ThemeDir()) |
| 67 | // if err != nil { |
| 68 | // th = theme.Default(p.ThemeDir()) |
| 69 | // } |
| 70 | func Load(name, userDir string) (*Theme, error) { |
| 71 | return loadNamed(name, userDir, 0) |
| 72 | } |
| 73 | |
| 74 | // Default returns the theme used when the user has not chosen one, honouring |
| 75 | // a file of that name in userDir the way Load does. |
| 76 | // |
| 77 | // The embedded file it reads is checked by a test, so this cannot fail in |
| 78 | // practice; if it ever did, a plain white-on-black theme is returned rather |
| 79 | // than nothing, because the editor must always have something to draw with. |
| 80 | func Default(userDir string) *Theme { |
| 81 | th, err := Load(DefaultName, userDir) |
| 82 | if err != nil { |
| 83 | return &Theme{ |
| 84 | name: DefaultName, |
| 85 | styles: map[string]tcell.Style{KeyDefault: fallbackStyle()}, |
| 86 | } |
| 87 | } |
| 88 | return th |
| 89 | } |
| 90 | |
| 91 | // Available returns the names of every theme that can be loaded, from userDir |
| 92 | // and from the ones embedded in the binary, sorted and without duplicates. |
| 93 | func Available(userDir string) []string { |
| 94 | seen := map[string]bool{} |
| 95 | for _, name := range embeddedNames() { |
| 96 | seen[name] = true |
| 97 | } |
| 98 | for _, name := range userNames(userDir) { |
| 99 | seen[name] = true |
| 100 | } |
| 101 | |
| 102 | names := make([]string, 0, len(seen)) |
| 103 | for name := range seen { |
| 104 | names = append(names, name) |
| 105 | } |
| 106 | sort.Strings(names) |
| 107 | return names |
| 108 | } |
| 109 | |
| 110 | // LoadFile reads a theme from a TOML file on disk. |
| 111 | // |
| 112 | // userDir is where a theme this one inherits from is looked for, and is |
| 113 | // otherwise unused. |
| 114 | func LoadFile(path, userDir string) (*Theme, error) { |
| 115 | return loadFileAt(path, userDir, 0) |
| 116 | } |
| 117 | |
| 118 | // loadFileAt is LoadFile plus the recursion depth, which must be carried |
| 119 | // across every hop of an "inherits" chain for the loop guard to see it. |
| 120 | func loadFileAt(path, userDir string, depth int) (*Theme, error) { |
| 121 | data, err := os.ReadFile(path) |
| 122 | if err != nil { |
| 123 | return nil, fmt.Errorf("theme: read %s: %w", path, err) |
| 124 | } |
| 125 | |
| 126 | th, err := parse(data, userDir, depth) |
| 127 | if err != nil { |
| 128 | return nil, fmt.Errorf("theme: %s: %w", path, err) |
| 129 | } |
| 130 | if th.name == "" { |
| 131 | th.name = strings.TrimSuffix(filepath.Base(path), ".toml") |
| 132 | } |
| 133 | return th, nil |
| 134 | } |
| 135 | |
| 136 | // Parse reads a theme from the content of a TOML file. |
| 137 | // |
| 138 | // Every colour is resolved eagerly, so a typo in a colour name is reported |
| 139 | // here rather than silently drawn in the terminal's default colour halfway |
| 140 | // through an editing session. |
| 141 | func Parse(data []byte, userDir string) (*Theme, error) { |
| 142 | return parse(data, userDir, 0) |
| 143 | } |
| 144 | |
| 145 | // parse is Parse plus the recursion depth, which caps chains of "inherits". |
| 146 | func parse(data []byte, userDir string, depth int) (*Theme, error) { |
| 147 | var f file |
| 148 | if _, err := toml.Decode(string(data), &f); err != nil { |
| 149 | return nil, fmt.Errorf("invalid TOML: %w", err) |
| 150 | } |
| 151 | |
| 152 | base, err := inheritedStyles(f.Inherits, userDir, depth) |
| 153 | if err != nil { |
| 154 | return nil, err |
| 155 | } |
| 156 | |
| 157 | styles, err := resolveStyles(f.Colors, base) |
| 158 | if err != nil { |
| 159 | return nil, err |
| 160 | } |
| 161 | |
| 162 | return &Theme{name: f.Name, description: f.Description, styles: styles}, nil |
| 163 | } |
| 164 | |
| 165 | // inheritedStyles returns the resolved styles of the parent theme, or a bare |
| 166 | // default when there is no parent. |
| 167 | func inheritedStyles(parent, userDir string, depth int) (map[string]tcell.Style, error) { |
| 168 | if parent == "" { |
| 169 | return map[string]tcell.Style{KeyDefault: fallbackStyle()}, nil |
| 170 | } |
| 171 | if depth >= maxInheritDepth { |
| 172 | return nil, fmt.Errorf("inherits: chain deeper than %d, probably a loop", maxInheritDepth) |
| 173 | } |
| 174 | |
| 175 | th, err := loadNamed(parent, userDir, depth+1) |
| 176 | if err != nil { |
| 177 | return nil, fmt.Errorf("inherits %q: %w", parent, err) |
| 178 | } |
| 179 | |
| 180 | styles := make(map[string]tcell.Style, len(th.styles)) |
| 181 | for key, style := range th.styles { |
| 182 | styles[key] = style |
| 183 | } |
| 184 | return styles, nil |
| 185 | } |
| 186 | |
| 187 | // resolveStyles turns the entries of a theme file into styles, resolving |
| 188 | // shallower keys first so that "syntax.keyword" can inherit from "syntax", |
| 189 | // and "syntax" from "default". |
| 190 | func resolveStyles(entries map[string]Entry, base map[string]tcell.Style) (map[string]tcell.Style, error) { |
| 191 | if _, ok := base[KeyDefault]; !ok { |
| 192 | base[KeyDefault] = fallbackStyle() |
| 193 | } |
| 194 | |
| 195 | for _, key := range byDepth(entries) { |
| 196 | style, err := entries[key].style(lookup(base, parentKey(key))) |
| 197 | if err != nil { |
| 198 | return nil, fmt.Errorf("colors.%q: %w", key, err) |
| 199 | } |
| 200 | base[key] = style |
| 201 | } |
| 202 | return base, nil |
| 203 | } |
| 204 | |
| 205 | // byDepth returns the keys of entries sorted by how many dots they contain, |
| 206 | // then alphabetically so that the order is stable. |
| 207 | func byDepth(entries map[string]Entry) []string { |
| 208 | keys := make([]string, 0, len(entries)) |
| 209 | for key := range entries { |
| 210 | keys = append(keys, key) |
| 211 | } |
| 212 | sort.Slice(keys, func(i, j int) bool { |
| 213 | di, dj := strings.Count(keys[i], "."), strings.Count(keys[j], ".") |
| 214 | if di != dj { |
| 215 | return di < dj |
| 216 | } |
| 217 | return keys[i] < keys[j] |
| 218 | }) |
| 219 | return keys |
| 220 | } |
| 221 | |
| 222 | // parentKey returns the key one level up: "syntax.keyword" gives "syntax", and |
| 223 | // a key with no dot gives KeyDefault. |
| 224 | func parentKey(key string) string { |
| 225 | if dot := strings.LastIndexByte(key, '.'); dot >= 0 { |
| 226 | return key[:dot] |
| 227 | } |
| 228 | return KeyDefault |
| 229 | } |
| 230 | |
| 231 | // lookup reads a key from resolved styles, walking up the dots as Style does. |
| 232 | func lookup(styles map[string]tcell.Style, key string) tcell.Style { |
| 233 | for { |
| 234 | if style, ok := styles[key]; ok { |
| 235 | return style |
| 236 | } |
| 237 | dot := strings.LastIndexByte(key, '.') |
| 238 | if dot < 0 { |
| 239 | return styles[KeyDefault] |
| 240 | } |
| 241 | key = key[:dot] |
| 242 | } |
| 243 | } |
| 244 | |
| 245 | // loadNamed is Load plus the recursion depth used by "inherits". |
| 246 | func loadNamed(name, userDir string, depth int) (*Theme, error) { |
| 247 | if err := validateName(name); err != nil { |
| 248 | return nil, err |
| 249 | } |
| 250 | |
| 251 | if userDir != "" { |
| 252 | path := filepath.Join(userDir, name+".toml") |
| 253 | if _, err := os.Stat(path); err == nil { |
| 254 | return loadFileAt(path, userDir, depth) |
| 255 | } |
| 256 | } |
| 257 | |
| 258 | // After the user's directory, never before it: somebody who has written |
| 259 | // their own monochrome.toml gets theirs, exactly as they would for any |
| 260 | // other name a shipped theme also answers to. |
| 261 | if current, retired := retiredNames[name]; retired { |
| 262 | name = current |
| 263 | } |
| 264 | |
| 265 | data, err := embeddedThemes.ReadFile(embeddedDir + "/" + name + ".toml") |
| 266 | if err != nil { |
| 267 | return nil, fmt.Errorf("%w: %q", ErrNotFound, name) |
| 268 | } |
| 269 | |
| 270 | th, err := parse(data, userDir, depth) |
| 271 | if err != nil { |
| 272 | return nil, fmt.Errorf("theme: embedded %s: %w", name, err) |
| 273 | } |
| 274 | if th.name == "" { |
| 275 | th.name = name |
| 276 | } |
| 277 | return th, nil |
| 278 | } |
| 279 | |
| 280 | // validateName rejects names that would let a theme reference escape the |
| 281 | // directories themes are meant to come from. |
| 282 | func validateName(name string) error { |
| 283 | if name == "" { |
| 284 | return fmt.Errorf("%w: empty name", ErrNotFound) |
| 285 | } |
| 286 | if strings.ContainsAny(name, `/\`) || strings.Contains(name, "..") { |
| 287 | return fmt.Errorf("%w: %q is not a plain theme name", ErrNotFound, name) |
| 288 | } |
| 289 | return nil |
| 290 | } |
| 291 | |
| 292 | // embeddedNames lists the themes compiled into the binary. |
| 293 | func embeddedNames() []string { |
| 294 | entries, err := embeddedThemes.ReadDir(embeddedDir) |
| 295 | if err != nil { |
| 296 | return nil |
| 297 | } |
| 298 | return tomlBaseNames(entries) |
| 299 | } |
| 300 | |
| 301 | // userNames lists the themes in the user's theme directory, which may well not |
| 302 | // exist. |
| 303 | func userNames(userDir string) []string { |
| 304 | if userDir == "" { |
| 305 | return nil |
| 306 | } |
| 307 | entries, err := os.ReadDir(userDir) |
| 308 | if err != nil { |
| 309 | return nil |
| 310 | } |
| 311 | return tomlBaseNames(entries) |
| 312 | } |
| 313 | |
| 314 | // tomlBaseNames returns the names of the .toml files among entries, without |
| 315 | // their extension. |
| 316 | func tomlBaseNames(entries []fs.DirEntry) []string { |
| 317 | var names []string |
| 318 | for _, entry := range entries { |
| 319 | if entry.IsDir() || !strings.HasSuffix(entry.Name(), ".toml") { |
| 320 | continue |
| 321 | } |
| 322 | names = append(names, strings.TrimSuffix(entry.Name(), ".toml")) |
| 323 | } |
| 324 | return names |
| 325 | } |