Returns an array that represents the _types_ of plans (i.e. offer classes) that should be offered to the customer. An empty array is returned if an offer class cannot be determined due to a coding error and the caller needs to handle accordingly.

getOfferClasses()

// getOfferClasses()
//
// Returns an array that represents the _types_ of plans (i.e. offer classes) that should be offered to the
// customer.  An empty array is returned if an offer class cannot be determined due to a coding error and the
// caller needs to handle accordingly.
//
// Parameters:
//     custSegment     - String customer segment ('A'-Port, 'B'-New, 'C'-Migrator, 'D'-Legacy, 'E'-Inner Circle)
//     deviceType      - String identifying type of device ('byo'-BYOD, 'c_pl'-Certified Preloved, 'new'-New Device)
//     isAppleICDevice - Boolean true if the device is Apple and qualified for an Inner Circle plan
//     inAppleStore    - Boolean true if customer is physically in an Apple store
//     isCompatible    - Boolean true if customers device is compatible with their current plan
//     isRecent        - Boolean true if device not active on the current subscribe nor any within 48 days 
//     isActive        - Boolean true if the 'isAlreadyActivated' attribute is true
//
// Note:  deviceType of 'new' describes the actual device SKU as opposed to its usage whereas
//        isRecent describes if the device is recently used by the customer.  isRecent is false
//        for a "phone taken out of my drawer" use case.
//
// Integer offer classes returned in array:
//     Empty Array:  Code error -- calling function needs to handle
//     0 - No plan (i.e. no offer class applies, transacton is not allowed)
//     1 - Current plan
//     2 - Promo plan
//     3 - Base plan
//     4 - Legacy plan

/* jshint esnext:true */

function getOfferClass(custSegment, deviceType, isAppleICDevice, inAppleStore, isCompatible, isRecent, isActive) {

    const noPlan = 0;
    const currentPlan = 1;
    const promoPlan = 2;
    const basePlan = 3;
    const legacyPlan = 4;

    // ** Safety Assertion **
    // Note: This is guard code to make sure this function receives the expected types for its parameters.  If
    //       invalids are passed then return to no offer class to caller (empty array)
    if (typeof custSegment  !== 'string'  || typeof deviceType   !== 'string'  || typeof isAppleICDevice !== 'boolean' || 
        typeof inAppleStore !== 'boolean' || typeof isCompatible !== 'boolean' || typeof isRecent !== 'boolean' ||
        typeof isActive     !== 'boolean') {
        console.error("One or more parameters passed to 'getOfferClass()' are not of the expected types");
        return [];
    }

    // Handle deviceType
    var isBYOD = (deviceType === "byo");
    var isCPL = (deviceType === "c_pl");
    var isNew = (deviceType === "new");  // Describes the SKU itself (~byo && ~c_pl)

    // ** Safety Assertion **
    // Note:  This is guard code to make sure we have been passed a valid deviceType attribute.  If an invalid
    //        value is passed, then return no offer class to caller (empty array)
    if (!isBYOD && !isCPL && !isNew) {
        console.error("An invalid device type of '" + deviceType + "' was passed to 'getOfferClass()'");
        return [];
    }

    // Handle porting and migrating customers
    if (custSegment === 'A' || custSegment === 'C') {
        return [promoPlan];
    }

    // New number customers in an Apple Store buying a new phone exception
    if (custSegment === 'B' && inAppleStore && isNew) {
        return [promoPlan];
    }

    // New number customers [and not in Apple store]
    if (custSegment === 'B') {
        return [basePlan];
    }

    // ** Safety assertion **
    // Note:  This is guard code in case 'A', 'B', and 'C' customers made it this far
    //        because a future developer does not handle them prior to this point in
    //        the code.  This would also fire if an invalid custSegment is passed.
    if (custSegment !== 'D' && custSegment !== 'E') {
        console.error("New, porting, or migrating customers are not being properly handled in 'getOfferClasses()'");
        return [];
    }

    // Legacy or IC BYOD customers
    if (isBYOD) {

        // Legacy BYOD customers with device not compatible with their current plan
        if (custSegment === "D" && !isCompatible) {
            return [basePlan, legacyPlan];
        }

        // Fallback for BYOD customers
        return [currentPlan];
    }

    // Legacy or IC Certified Pre-Loved customers
    if (isCPL) {

        // Legacy CPL customers with a non-recent device and plan that is not compatible with that device
        if (custSegment === 'D' && !isRecent && !isCompatible) {
            return [promoPlan];
        }

        // Legacy CPL customers with a non-recent device [and compatible plan]
        if (custSegment === 'D' && !isRecent) {
            return [currentPlan, promoPlan];
        }

        // Legacy CPL customers with a recent device that is not compatible
        if (custSegment === 'D' && !isCompatible) {
            return [basePlan, legacyPlan];
        }

        // IC customers with a non-recent device
        if (custSegment !== 'D' && !isRecent) {
            return [promoPlan];
        }

        // Fallback for CPL customers
        return [currentPlan];
    }

    // Active legacy customers with an IC compatible device but with a plan
    // that is not compatible with their new device
    if (custSegment === 'D' && isAppleICDevice && !isCompatible && isActive) {
        return [basePlan, legacyPlan];
    }

    // Inactive legacy customers with an IC compatible device but with a
    // plan that is not compatible with their new device
    if (custSegment === 'D' && isAppleICDevice && !isCompatible) {
        return [promoPlan];
    }

    // Active legacy customers with a plan compatible with thier new device
    if (custSegment === 'D' && isCompatible && isActive) {
        return [currentPlan];
    }

    // Inacitve legacy customers with a plan compatible with their new device
    if (custSegment === 'D' && isCompatible) {
        return [currentPlan, promoPlan];
    }
    
    // Active legacy customers
    if (custSegment === 'D' && isActive) {
        return [legacyPlan];
    }

    // Inactive legacy customers
    if (custSegment === 'D') {
        return [promoPlan];
    }
    
    // Active IC customers with a currnet plan compatible with new device
    if (custSegment === 'E' && isCompatible && isActive) {
        return [currentPlan];
    }

    // Inactive IC customers
    if (custSegment === 'E' && !isActive) {
        return [promoPlan];
    }

    // Active IC customers
    if (custSegment === 'E') {
        return [noPlan];
    }

    // Fallback always on current plan
    // Note: New customers, porting, and migrating customers never make it here
    return [currentPlan];

}

// Test function
// Loops through all possible call values
function test() {
    const tlist = ["A", "B", "C", "D", "E"];
    const dlist = ["byo", "c_pl", "new"];
    console.log('"Segment","DeviceType","isAppleIC?","inStore?","Compatible?","Recent?","Active?","Result"');
    for (var t = 0; t < tlist.length; t++) {
        for (var d = 0; d < dlist.length; d++) {
            for (var bit = 0; bit < 32; bit++) {
                isActive     = ((bit & (1 << 0)) !== 0); // tests to see if bit zero is set
                isRecent     = ((bit & (1 << 1)) !== 0);
                isCompatible = ((bit & (1 << 2)) !== 0);
                isInStore    = ((bit & (1 << 3)) !== 0);
                isAppleIC    = ((bit & (1 << 4)) !== 0);
                results = getOfferClass(tlist[t], dlist[d], isAppleIC, isInStore, isCompatible, isRecent, isActive);
                console.log(['"'+tlist[t]+'"', '"'+dlist[d]+'"', isAppleIC, isInStore, isCompatible, isRecent, isActive, '"'+results+'"'].join());
            }
        }
    }
}

test();