package cli

import (
	"fmt"
	"io"

	"gogs.inhome.blapointe.com/ana-ledger/src/ledger"
)

type Query struct{}

func BuildQuery(args args) (ledger.Like, error) {
	likes := make(ledger.Likes, 0)

	for _, ok := args.peek(); ok; _, ok = args.peek() {
		like, err := buildOneQuery(args)
		if err != nil {
			return nil, err
		}
		likes = append(likes, like)
	}

	return likes.Any, nil
}

func buildOneQuery(args args) (ledger.Like, error) {
	word, ok := args.peek()
	if !ok {
		return nil, io.EOF
	}

	likes := make(ledger.Likes, 0)

	for _, ok := args.peek(); ok; _, ok = args.peek() {
		switch word {
		case "and":
			if len(likes) == 0 {
				return nil, fmt.Errorf("and without predicate")
			}
			args.pop()
			like, err := buildOneQuery(args)
			if err != nil {
				return nil, err
			}
			likes = append(likes, like)
		case "not":
			args.pop()
			like, err := buildOneQuery(args)
			if err != nil {
				return nil, err
			}
			likes = append(likes, like)
		default:
			return nil, io.EOF
			if next, _ := args.peek(); next != "and" {
				return likes.All, nil
			}
		}
	}
	return nil, io.EOF
}

type args []string

func (args *args) pop() string {
	first := (*args)[0]
	*args = (*args)[1:]
	return first
}

func (args *args) peek() (string, bool) {
	if len(*args) == 0 {
		return "", false
	}
	return (*args)[0], true
}