package q03

import (
	_ "embed"
	"fmt"
	"math/rand"
	"strconv"
	"strings"
	"text/template"

	"github.com/hhhapz/codequest/models"
	"github.com/hhhapz/codequest/question"
)

type weightedChoice struct {
	weight int
	value  int
}

func weightedRandom(choices []weightedChoice, r *rand.Rand) int {
	var total int
	for _, c := range choices {
		total += c.weight
	}

	rnd := r.Intn(total)
	for _, c := range choices {
		if rnd < c.weight {
			return c.value
		}
		rnd -= c.weight
	}
	panic("unreachable")
}

func init() {
	t := template.New("dragon")
	var err error
	t, err = t.Parse(q03Text)
	if err != nil {
		panic(err)
	}
	question.Register(
		&question.Question{
			ID:    "dragon",
			Name:  "The Dragon Festival",
			Text:  t,
			Level: question.Level1,
			Generate: func(u *models.User) string {
				inp := generate(u)
				res := make([]string, rows)

				for i, row := range inp {
					for _, n := range row {
						res[i] += strconv.Itoa(n)
					}
				}
				return strings.Join(res, "\n")
			},
			Validate: func(u *models.User, part question.Part, solution string) bool {
				return Validate(u, part, solution)
			},
		})
}

const (
	rows = 120
	cols = 80
)

var numWeights = []weightedChoice{
	{weight: 1, value: 0},
	{weight: 4, value: 1},
	{weight: 4, value: 2},
	{weight: 4, value: 3},
	{weight: 4, value: 4},
	{weight: 4, value: 5},
	{weight: 4, value: 6},
	{weight: 2, value: 7},
	{weight: 2, value: 8},
	{weight: 1, value: 9},
}

func generate(u *models.User) [][]int {
	res := make([][]int, rows)

	r := question.UserRandom(u)

	for i := 0; i < rows; i++ {
		res[i] = make([]int, cols)
		for j := 0; j < cols; j++ {
			res[i][j] = weightedRandom(numWeights, r)
		}
	}

	return res
}

func Validate(u *models.User, p question.Part, sol string) bool {
	inp := generate(u)

	var n int
	switch p {
	case question.Part1:
		n = solveP1(inp)
	case question.Part2:
		n = solveP2(inp)

	default:
		return false
	}

	fmt.Println("submitted", sol)
	fmt.Println("actual", n)
	return strconv.Itoa(n) == sol
}

//go:embed q03.md
var q03Text string