package main

import (
	"bufio"
	"fmt"
	"os"
	"strings"
)

func parseFunc(s string) value {
	if !isList(s) {
		return value{val: s}
	}
	list := parseList(s)
	if len(list) != 2 || !isList(list[0]) || !isList(list[1]) {
		return value{val: s, list: list}
	}
	param := parseList(list[0])
	for _, name := range param {
		if !isName(`"` + name) {
			return value{val: s, list: list}
		}
	}
	local := make(environ)
	for name, val := range env[len(env)-1] {
		local[name] = val
	}
	return value{val: s, list: list, param: param, env: local}
}

func getFunc(name string) value {
	if !isName(`"` + name) {
		return value{}
	}
	envs := []int{len(env) - 1, len(env) - 2, 1}
	for _, id := range envs {
		val, ok := env[id][name]
		if ok {
			return val
		}
	}
	return value{}
}

func opMake(val1, val2 value) value {
	name := toName(val1.val)
	_, ok := reserved[name]
	if ok {
		panic(fmt.Errorf("make: %s (%s)", errNameReserved, name))
	}
	if isList(val2.val) && val2.list == nil {
		val2 = parseFunc(val2.val)
	}
	env[len(env)-1][name] = val2
	return val2
}

func opThing(val1 value) value {
	name := toName(val1.val)
	envs := []int{len(env) - 1, len(env) - 2, 1}
	for _, id := range envs {
		val, ok := env[id][name]
		if ok {
			return val
		}
	}
	panic(fmt.Errorf("thing: %s (%s)", errNameNotFound, name))
}

func opErase(val1 value) value {
	name := toName(val1.val)
	val, ok := env[len(env)-1][name]
	if ok {
		delete(env[len(env)-1], name)
		return val
	}
	panic(fmt.Errorf("erase: %s (%s)", errNameNotFound, name))
}

func opExport(val1 value) value {
	name := toName(val1.val)
	val, ok := env[len(env)-1][name]
	if ok {
		env[1][name] = val
		return val
	}
	panic(fmt.Errorf("export: %s (%s)", errNameNotFound, name))
}

func opSave(val1 value) value {
	name := toName(val1.val)
	s := ""
	for name, val := range env[len(env)-1] {
		s += `make "` + name + " " + val.val + "\n"
	}
	err := os.WriteFile(name, []byte(s), 0666)
	if err != nil {
		panic(fmt.Errorf("save: %s (%s)", errFileError, name))
	}
	return val1
}

func opLoad(val1 value) value {
	name := toName(val1.val)
	s, err := os.ReadFile(name)
	if err != nil {
		panic(fmt.Errorf("load: %s (%s)", errFileError, name))
	}
	interpret(bufio.NewScanner(strings.NewReader(string(s))))
	return value{val: "true"}
}

func opErAll() value {
	env[len(env)-1] = make(environ)
	return value{val: "true"}
}

func opPoAll() value {
	list := []string{}
	for name := range env[len(env)-1] {
		list = append(list, name)
	}
	return value{val: "[ " + strings.Join(list, " ") + " ]"}
}