package main

import (
	"fmt"
	"strings"
)

func opWord(val1, val2 value) value {
	if !isWord(val1.val) {
		panic(fmt.Errorf("word: %s (%s)", errWordExpceted, val1.val))
	}
	if isWord(val2.val) {
		return value{val: val1.val + val2.val[1:]}
	}
	if isNumber(val2.val) || isBool(val2.val) {
		return value{val: val1.val + val2.val}
	}
	panic(fmt.Errorf("word: %s (%s)", errWordExpceted, val2.val))
}

func opSentence(val1, val2 value) value {
	return value{val: "[ " +
		strings.TrimSuffix(strings.TrimPrefix(val1.val, "[ "), " ]") + " " +
		strings.TrimSuffix(strings.TrimPrefix(val2.val, "[ "), " ]") + " ]"}
}

func opList(val1, val2 value) value {
	return value{val: "[ " + val1.val + " " + val2.val + " ]"}
}

func opJoin(val1, val2 value) value {
	if !isList(val1.val) {
		panic(fmt.Errorf("join: %s (%s)", errListExpected, val1.val))
	}
	return value{val: strings.TrimSuffix(val1.val, " ]") + " " + val2.val + " ]"}
}

func opFirst(val1 value) value {
	if !isWord(val1.val) && !isList(val1.val) {
		panic(fmt.Errorf("first: %s (%s)", errWordOrListExpected, val1.val))
	}
	if isEmpty(val1.val) {
		panic(fmt.Errorf("first: %s (%s)", errEmptyWordOrList, val1.val))
	}
	if isWord(val1.val) {
		return value{val: val1.val[1:2]}
	}
	list1 := strings.Split(val1.val, " ")
	if list1[1] != "[" {
		return value{val: list1[1]}
	}
	i, bracketCnt := 2, 1
	for ; bracketCnt > 0; i++ {
		if list1[i] == "[" {
			bracketCnt++
		}
		if list1[i] == "]" {
			bracketCnt--
		}
	}
	return value{val: strings.Join(list1[1:i], " ")}
}

func opLast(val1 value) value {
	if !isWord(val1.val) && !isList(val1.val) {
		panic(fmt.Errorf("last: %s (%s)", errWordOrListExpected, val1.val))
	}
	if isEmpty(val1.val) {
		panic(fmt.Errorf("last: %s (%s)", errEmptyWordOrList, val1.val))
	}
	if isWord(val1.val) {
		return value{val: val1.val[len(val1.val)-1:]}
	}
	list1 := strings.Split(val1.val, " ")
	if list1[len(list1)-2] != "]" {
		return value{val: list1[len(list1)-2]}
	}
	i, bracketCnt := len(list1)-3, 1
	for ; bracketCnt > 0; i-- {
		if list1[i] == "]" {
			bracketCnt++
		}
		if list1[i] == "[" {
			bracketCnt--
		}
	}
	return value{val: strings.Join(list1[i+1:len(list1)-1], " ")}
}

func opButFirst(val1 value) value {
	if !isWord(val1.val) && !isList(val1.val) {
		panic(fmt.Errorf("butfirst: %s (%s)", errWordOrListExpected, val1.val))
	}
	if isEmpty(val1.val) {
		panic(fmt.Errorf("butfirst: %s (%s)", errEmptyWordOrList, val1.val))
	}
	if isWord(val1.val) {
		return value{val: `"` + val1.val[2:]}
	}
	list1 := strings.Split(val1.val, " ")
	if list1[1] != "[" {
		return value{val: "[ " + strings.Join(list1[2:], " ")}
	}
	i, bracketCnt := 2, 1
	for ; bracketCnt > 0; i++ {
		if list1[i] == "[" {
			bracketCnt++
		}
		if list1[i] == "]" {
			bracketCnt--
		}
	}
	return value{val: "[ " + strings.Join(list1[i:], " ")}
}

func opButLast(val1 value) value {
	if !isWord(val1.val) && !isList(val1.val) {
		panic(fmt.Errorf("butlast: %s (%s)", errWordOrListExpected, val1.val))
	}
	if isEmpty(val1.val) {
		panic(fmt.Errorf("butlast: %s (%s)", errEmptyWordOrList, val1.val))
	}
	if isWord(val1.val) {
		return value{val: val1.val[:len(val1.val)-1]}
	}
	list1 := strings.Split(val1.val, " ")
	if list1[len(list1)-2] != "]" {
		return value{val: strings.Join(list1[:len(list1)-2], " ") + " ]"}
	}
	i, bracketCnt := len(list1)-3, 1
	for ; bracketCnt > 0; i-- {
		if list1[i] == "]" {
			bracketCnt++
		}
		if list1[i] == "[" {
			bracketCnt--
		}
	}
	return value{val: strings.Join(list1[:i+1], " ") + " ]"}
}