package server

import (
	"regexp"
)

type env struct {
	m map[string]string
}

const varNamePattern = "[a-zA-Z][a-zA-Z0-9]*"

var isValidVarName = regexp.MustCompile("^" + varNamePattern + "$").MatchString

var varTokenRe = regexp.MustCompile("@" + varNamePattern)

func (e *env) get(key string) (string, bool) {
	v, ok := e.m[key]

	return v, ok
}

func (e *env) set(key string, value string) {
	if e.m == nil {
		e.m = make(map[string]string)
	}

	e.m[key] = value
}

func (e *env) del(key string) bool {
	if e.m == nil {
		return false
	}

	if _, ok := e.m[key]; !ok {
		return false
	}

	delete(e.m, key)

	return true
}

func (e *env) each(f func (string, string) bool) {
	for k, v := range e.m {
		if !f(k, v) {
			break
		}
	}
}

func (e *env) clear() {
	e.m = nil
}

func varGet(r *request) {
	r.expect(1)

	if v, ok := r.c.s.env.get(r.args[0]); ok {
		r.Print(v)
	} else {
		r.Fatal("no such variable")
	}
}

func varSet(r *request) {
	r.expect(2)

	if !isValidVarName(r.args[0]) {
		r.Fatal("bad variable name")
	}

	r.c.s.env.set(r.args[0], r.args[1])
}

func varDel(r *request) {
	r.expect(1)

	if !r.c.s.env.del(r.args[0]) {
		r.Fatal("no such variable")
	}
}

func varShow(r *request) {
	r.c.s.env.each(func (k string, v string) bool {
		r.Println(k, v)
		return true
	})
}

func varClear(r *request) {
	r.c.s.env.clear()
}

func init() {
	newCmd(varGet,  "var get")
	newCmd(varSet,  "var set")
	newCmd(varDel,  "var del")
	newCmd(varShow, "var show")
	newCmd(varClear, "var clear")
}