Initial commit

ini.go

@@ -0,0 +1,168 @@
+package camfish
+
+import "os"
+import "io"
+import "fmt"
+import "iter"
+import "slices"
+import "strings"
+import "strconv"
+import "path/filepath"
+
+type iniConfig map[string] []iniValue
+
+type iniValue struct {
+	value  string
+	file   string
+	line   int
+	column int
+}
+
+// ParseINI parses a string containing INI configuration data.
+func ParseINI(filename, input string) (MutableConfig, error) {
+	ini := make(iniConfig)
+	configErr := ConfigError {
+		File: filename,
+	}
+	section := ""
+	for index, line := range strings.Split(input, "\n") {
+		configErr.Line = index + 1
+		configErr.Key  = ""
+		line = strings.TrimSpace(line)
+		if line == ""                   { continue }
+		if strings.HasPrefix(line, "#") { continue }
+		if strings.HasPrefix(line, "[") {
+			// section heading
+			if !strings.HasSuffix(line, "]") {
+				configErr.Err = ErrSectionHeadingMalformed
+				return nil, configErr
+			}
+			section = strings.TrimSpace(strings.TrimSuffix(strings.TrimPrefix(line, "["), "]"))
+			if section == "" {
+				configErr.Err = ErrSectionHeadingMalformed
+				return nil, configErr
+			}
+			continue
+		}
+
+		// split key/value
+		key, value, ok := strings.Cut(line, "=")
+		if !ok {
+			configErr.Err = ErrPairMalformed
+			return nil, configErr
+		}
+
+		// key
+		key = strings.TrimSpace(key)
+		if key == "" {
+			configErr.Err = ErrKeyEmpty
+			return nil, configErr
+		}
+		configErr.Key = key
+		if section != "" {
+			key = fmt.Sprintf("%s.%s", section, key)
+		}
+
+		// value
+		value = strings.TrimSpace(value)
+		if strings.HasPrefix(value, "\"") || strings.HasPrefix(value, "'") {
+			unquoted, err := strconv.Unquote(value)
+			if err != nil {
+				configErr.Column = strings.Index(line, "=") + 2
+				configErr.Err = err
+				return nil, configErr
+			}
+			value = unquoted
+		}
+		ini.Add(key, value)
+	}
+	return ini, nil
+}
+
+// DecodeINI decodes INI data from an io.Reader. The entire reader is consumed.
+func DecodeINI(filename string, input io.Reader) (MutableConfig, error) {
+	buffer, err := io.ReadAll(input)
+	if err != nil { return nil, err }
+	return ParseINI(filename, string(buffer))
+}
+
+func (ini iniConfig) Add(key, value string) {
+	key = canonicalINIKey(key)
+	ini[key] = append(ini[key], iniValue {
+		value: value,
+	})
+}
+
+func (ini iniConfig) Del(key string) {
+	key = canonicalINIKey(key)
+	delete(ini, key)
+}
+
+func (ini iniConfig) Get(key string) string {
+	key = canonicalINIKey(key)
+	slice, ok := ini[key]
+	if !ok             { return "" }
+	if len(slice) == 0 { return "" }
+	return slice[0].value
+}
+
+func (ini iniConfig) GetAll(key string) iter.Seq2[int, string] {
+	return func(yield func(int, string) bool) {
+		for index, value := range ini[key] {
+			if !yield(index, value.value) { return }
+		}
+	}
+}
+
+func (ini iniConfig) Set(key, value string) {
+	key = canonicalINIKey(key)
+	valueInfo := iniValue { }
+	if prevValues := ini[key]; len(prevValues) > 0 {
+		valueInfo = prevValues[0]
+	}
+	valueInfo.value = value
+	ini[key] = []iniValue { valueInfo }
+}
+
+func (ini iniConfig) NewConfigError(key string, index int, wrapped error) ConfigError {
+	if values, ok := ini[key]; ok {
+		if index > 0 && index < len(values) {
+			value := values[index]
+			return ConfigError {
+				File:   value.file,
+				Key:    key,
+				Line:   value.line,
+				Column: value.column,
+				Err:    wrapped,
+			}
+		}
+	}
+	return ConfigError {
+		Key: key,
+		Err: wrapped,
+	}
+}
+
+func canonicalINIKey(key string) string {
+	return strings.ToLower(key)
+}
+
+func mergeINI(inis ...iniConfig) iniConfig {
+	ini := make(iniConfig)
+	for index := len(inis) - 1; index >= 0; index -- {
+		for key, values := range inis[index] {
+			if _, exists := ini[key]; exists { continue }
+			ini[key] = slices.Clone(values)
+		}
+	}
+	return ini
+}
+
+func configFiles(program string) ([]string, error) {
+	userConfig, err := os.UserConfigDir()
+	if err != nil { return nil, err }
+	return []string {
+		filepath.Join("/etc", program),
+		filepath.Join(userConfig, program),
+	}, nil
+}