package envconf

import ("strings"
        "unicode"
        "os")

type DataType int

const (
    TypeNone DataType = iota
    TypeUnset DataType = iota
    TypeInt DataType = iota
    TypeDuration DataType = iota
    TypeString DataType = iota
)

type cEntry struct {
    value string
    dtype DataType
}

type Config struct {
    env map[string]cEntry
}

func getFirstRune(str string)(rune) {
    for _,v := range str {
        return v
    }
    return rune(0)
}

func NewConfig()(*Config) {
    config := new(Config)
    config.env = make(map[string]cEntry)
    for _,v := range os.Environ() {
        splitted := strings.SplitN(v, "=", 2)
        if len(splitted) == 2 {
            key := strings.TrimSpace(strings.ToLower(splitted[0]))
            if unicode.IsLetter(getFirstRune(key)) {
                var entry cEntry
                entry.value = splitted[1]
                entry.dtype = TypeNone
                config.env[key] = entry
            }
        }
    }
    return config
}

func (c *Config) Define(key string, dtype DataType) {
    entry, ok := c.env[key]
    if ok {
        entry.dtype = dtype
    } else {
        var entry cEntry
        entry.dtype = TypeUnset
        c.env[key] = entry
    }
}