import { REGIONS } from "../config/regions.js"
import { getState, updateBalance, unlockGate, returnBalance } from "../save/state.js"

/**
 * Can this region be unlocked right now, and if not, why not?
 *
 * Returns an outcome object rather than a boolean so callers can explain the
 * refusal to the player. `reason` is a code, not display text - whoever shows
 * it is responsible for turning it into a translated message.
 *
 *   { ok: true }
 *   { ok: false, reason: "unknown_region" }                          developer error
 *   { ok: false, reason: "already_unlocked" }
 *   { ok: false, reason: "missing_prior_region", requires: "farmland" }
 *   { ok: false, reason: "insufficient_funds", cost: 500, balance: 120 }
 *
 * @param {string} regionID - a REGIONS key, e.g. "farmland"
 */
export function canUnlock(regionID) {

    /* 
    the region's whole config record: 
    { nameKey, order, unlockedAtStart, unlockedCost}
    */ 
    const region = REGIONS[regionID];
    if (region === undefined) {
        return { ok: false, reason: "unknown_region" };
    }
    // order number from the REGIONS section we keyed
    const order = region.order;
    // we return the full record.
    const gates = getState().gates;
    /* 
    if the records value for that key's order is 
    true: unlocked
    */ 
    if (gates[regionID] === true) {
        return { ok: false, reason: "already_unlocked" };
    }

    /*
    WE ARE KEYING FOR THE KEY VALUE'S ORDER PRIOR TO PASSED REGION{RegionID}
    the prior value has to be true for the passed region to unlock
    */
    let priorRegion = null;
    for (const id in REGIONS) {
        // never pass lagoon otherwise all conditions fail
        if (REGIONS[id].order === order - 1) {
        /*
        again tdlr we get the key prior to the past key
        so for example command canUnlock("seaside");
        we are retrieving farm land for comparison
        it's sequential you can't unlock zones non 
        out of order
        */
            priorRegion = id;
        }
    }

    // if first region is auto unlocked we will never meet this condition
    if (priorRegion === null) {
        return { ok: false, reason: "missing_prior_region", requires: null };
    }

    /*
    the prior region before this one must be open first
    */
    if (gates[priorRegion] !== true) {
        return { ok: false, reason: "missing_prior_region", requires: priorRegion };
    }

    //they have to be able to pay for it.
    const cost = region.unlockedCost;
    const balance = returnBalance();
    if (balance < cost) {
        return { ok: false, reason: "insufficient_funds", cost: cost, balance: balance };
    }

    return { ok: true };
}

/**
 * Unlocks a region if the rules allow it, charges the cost, and saves.
 * object canUnlock produced and can explain what went wrong.
 *
 * @param {string} regionID - a REGIONS key, e.g. "farmland"
 */
export function unlockRegion(regionID) {

    const result = canUnlock(regionID);
    if (!result.ok) {
        return result;
    }

    unlockGate(regionID, true);

    /*
    always make sure things that cost money are passed negative,
    because otherwise it would add to the balance
    */
    updateBalance(-REGIONS[regionID].unlockedCost);

    return { ok: true };
}