Initial spike

This is mostly to solidify the overall structure with the agent,
plugins, and testing philosphy.

config.go

@@ -0,0 +1,103 @@
+package tivan
+
+import (
+	"errors"
+	"fmt"
+	"io/ioutil"
+	"sort"
+	"strings"
+	"time"
+
+	"github.com/naoina/toml"
+	"github.com/naoina/toml/ast"
+)
+
+type Duration struct {
+	time.Duration
+}
+
+func (d *Duration) UnmarshalTOML(b []byte) error {
+	dur, err := time.ParseDuration(string(b[1 : len(b)-1]))
+	if err != nil {
+		return err
+	}
+
+	d.Duration = dur
+
+	return nil
+}
+
+type Config struct {
+	URL       string
+	Username  string
+	Password  string
+	Database  string
+	UserAgent string
+	Tags      map[string]string
+
+	plugins map[string]*ast.Table
+}
+
+func (c *Config) Plugins() map[string]*ast.Table {
+	return c.plugins
+}
+
+func (c *Config) Apply(name string, v interface{}) error {
+	if tbl, ok := c.plugins[name]; ok {
+		return toml.UnmarshalTable(tbl, v)
+	}
+
+	return nil
+}
+
+func DefaultConfig() *Config {
+	return &Config{}
+}
+
+var ErrInvalidConfig = errors.New("invalid configuration")
+
+func LoadConfig(path string) (*Config, error) {
+	data, err := ioutil.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+
+	tbl, err := toml.Parse(data)
+	if err != nil {
+		return nil, err
+	}
+
+	c := &Config{
+		plugins: make(map[string]*ast.Table),
+	}
+
+	for name, val := range tbl.Fields {
+		subtbl, ok := val.(*ast.Table)
+		if !ok {
+			return nil, ErrInvalidConfig
+		}
+
+		if name == "influxdb" {
+			err := toml.UnmarshalTable(subtbl, c)
+			if err != nil {
+				return nil, err
+			}
+		} else {
+			c.plugins[name] = subtbl
+		}
+	}
+
+	return c, nil
+}
+
+func (c *Config) ListTags() string {
+	var tags []string
+
+	for k, v := range c.Tags {
+		tags = append(tags, fmt.Sprintf("%s=%s", k, v))
+	}
+
+	sort.Strings(tags)
+
+	return strings.Join(tags, " ")
+}