import type { MainStat } from "~/types/character";
import { MAIN_STATS, mainStatShortTexts } from "./character";
import type { Proxy } from "./reactive";

//[Quantité de dés, Nb de face du dé (1 = pas besoin de roll de dé), explosif]
export type Dice = [number, number | MainStat] | [number, number | MainStat, true];
export type DiceRoll = Dice[];

enum State {
    START,
    QUANTITY,
    D_LETTER,
    FACES_NUMBER,
    FACES_STAT,
    MODIFIER_SIGN,
    MODIFIER,
    EXPLODING,
    END_DICE,
};

export function parseDice(formula: string): DiceRoll
{
    const result: DiceRoll = [];
    let state = State.START;

    let i = 0, length = formula.length;

    //Variables utilitaires de la State machine
    let buffer = "";
    let isExploding = false, isNegative = false, currentQty = 1, currentFaces: number | MainStat = 1;

    const reset = () => {
        if (state !== State.START && state !== State.END_DICE)
        {
            const dice: Dice = isExploding ? [currentQty, currentFaces, true] : [currentQty, currentFaces];

            if (isNegative)
            {
                dice[0] = -dice[0];
                isNegative = false;
            }

            result.push(dice);
        }
        
        currentQty = 1;
        currentFaces = 1;
        isExploding = false;
        buffer = "";
    };

    while(i <= length)
    {
        const char = i < length ? formula[i]?.toLowerCase() ?? '\0' : '\0';
        const isDigit = char >= '0' && char <= '9';
        const isLetter = char >= 'a' && char <= 'z';
        const isEnd = i === length;

        switch (state) {
            case State.START:
                if (isDigit)
                {
                    buffer = char;
                    state = State.QUANTITY;
                }
                else if (char === 'd')
                {
                    currentQty = 1;
                    state = State.D_LETTER;
                }
                else if (isLetter)
                {
                    buffer = char;
                    state = State.FACES_STAT;
                }
                else if (char === '+' || char === '-')
                {
                    isNegative = char === '-';
                    state = State.MODIFIER_SIGN;
                }
                else if (!isEnd && char !== ' ' && char !== '\t')
                    throw new Error(`Caractère inattendu '${char}' à la position ${i}`);

                break;

            case State.QUANTITY:
                if (isDigit)
                    buffer += char;
                else if (char === 'd')
                {
                    currentQty = parseInt(buffer, 10) || 1;
                    buffer = "";
                    state = State.D_LETTER;
                }
                else
                {
                    currentQty = parseInt(buffer, 10);
                    currentFaces = 1;
                    reset();
                    state = State.END_DICE;
                    i--;
                }
                break;

            case State.D_LETTER:
                if (isDigit)
                {
                    buffer = char;
                    state = State.FACES_NUMBER;
                }
                else if (isLetter)
                {
                    buffer = 'd' + char;
                    state = State.FACES_STAT;
                }
                else
                    throw new Error(`Attendu nombre ou stat après 'd' à la position ${i}`);
                
                break;

            case State.FACES_NUMBER:
                if (isDigit)
                    buffer += char;
                else if (char === '!')
                {
                    currentFaces = parseInt(buffer, 10);
                    state = State.EXPLODING;
                }
                else
                {
                    currentFaces = parseInt(buffer, 10);
                    reset();
                    state = State.END_DICE;
                    i--;
                }
                break;

            case State.FACES_STAT:
                if (isLetter && buffer.length < 3)
                    buffer += char;
                else if (char === '!')
                {
                    const stat = validStat(buffer);
                    if (!stat)
                        throw new Error(`Stat invalide '${buffer}' à la position ${i - buffer.length}`);

                    currentFaces = stat;
                    state = State.EXPLODING;
                }
                else
                {
                    const stat = validStat(buffer);
                    if (!stat)
                        throw new Error(`Stat invalide '${buffer}' à la position ${i - buffer.length}`);

                    currentFaces = stat;
                    reset();
                    state = State.END_DICE;
                    i--;
                }
                break;

            case State.EXPLODING:
                isExploding = true;
                reset();
                state = State.END_DICE;
                i--;
                break;

            case State.MODIFIER_SIGN:
                if (isDigit)
                {
                    buffer = char;
                    state = State.MODIFIER;
                }
                else if (char === 'd')
                {
                    currentQty = 1;
                    state = State.D_LETTER;
                }
                else if (isLetter)
                {
                    buffer = char;
                    state = State.FACES_STAT;
                }
                else
                    throw new Error(`Attendu nombre après '${isNegative ? "-" : "+"}' à la position ${i}`);
                break;

            case State.MODIFIER:
                if (isDigit)
                    buffer += char;
                else
                {
                    currentQty = parseInt(buffer, 10);
                    currentFaces = 1;
                    if (isNegative) currentQty = -currentQty;
                    reset();
                    isNegative = false;
                    state = State.END_DICE;
                    i--;
                }
                break;

            case State.END_DICE:
                if (char === '+' || char === '-')
                {
                    isNegative = char === '-';
                    state = State.MODIFIER_SIGN;
                }
                else if (char === 'd')
                {
                    currentQty = 1;
                    state = State.D_LETTER;
                }
                else if (!isEnd && char !== ' ' && char !== '\t')
                    throw new Error(`Opérateur attendu, trouvé '${char}' à la position ${i}`);
                break;
        }

        i++;
    }

    return result;
}
export function stringifyRoll(dices: DiceRoll, modifiers?: Proxy<Partial<Record<MainStat, number>>>, explicit?: boolean): string
{
    const map = new Map<string, number>();
    dices.forEach(e => {
        if(e[0] === 0 || e[1] === 0) return;
        const target = typeof e[1] === 'string' ? modifiers && e[1] in modifiers ? modifiers[e[1]]! * e[0] : `@${e[1]}` : e[0]; //@ character used to sort the stat dices at the end
        const key = typeof e[1] === 'string' ? typeof target === 'string' ? e[1] : '1' : e[2] ? e[1].toString(10) + '!' : e[1].toString(10), value = map.get(key);
        if(typeof target === 'string') map.has(target) ? map.set(target, 1) : map.set(target, map.get(target)! + 1);
        else value === undefined ? map.set(key, target) : map.set(key, value + target);
    });

    const stringify = ([face, amount]: [string, number]) => (face.startsWith('@') && MAIN_STATS.includes(face.substring(1) as MainStat)) || face === '1' ? `${amount < 0 ? '-' : '+'}${face.startsWith('@') && MAIN_STATS.includes(face.substring(1) as MainStat) ? mainStatShortTexts[face.substring(1) as MainStat]! : amount}` : `${amount < 0 ? '-' : '+'}${explicit ?? false ? amount : amount !== 1 ? amount : ''}d${face}`;
    const text = [...map.entries()].sort((a, b) => b[0].localeCompare(a[0])).reduce((p, v) => p + stringify(v), '');
    return text.startsWith('+') ? text.substring(1) : text;
}
function validStat(text: string): MainStat | undefined
{
    return Object.entries(mainStatShortTexts).find(e => e[1].toLowerCase() === text.toLowerCase())?.at(0) as MainStat | undefined;
}