import type { CampaignCapabilities } from '../../../services/CampaignService';
// WHETHER THIS PRACTICE CAN SEND A CAMPAIGN BY TEXT, AND IF NOT, WHICH THING IS MISSING.
//
// The composer offered "Also send as a text message" as an ordinary enabled control at a practice with
// SMS off and no carrier registration, opened a text editor for it, and quoted a per-recipient price.
// A quoted price reads as a statement that the send is available and this is what it costs, so the
// practice writes the message and meets the refusal - wherever it lives - after the work.
//
// THE REASON IS NAMED, NOT JUST THE CONTROL DISABLED. Not on the plan and registration not finished are
// different states with different remedies, and a greyed control with no sentence sends an administrator
// hunting for a setting they may already have switched on. A refusal names what is refused; that rule
// does not stop applying because the refusal is a checkbox.
//
// THREE STATES, AND THE THIRD IS THE ONE THIS CODEBASE KEEPS PAYING FOR. `undefined` is NOT KNOWN - a
// read that failed, or a server older than this client - and it must never coalesce to "unavailable".
// Telling a practice it cannot send on the strength of a fact nobody measured is the same false
// assertion as telling a patient they have no appointments when the request was refused.

export type SmsChannelAvailability =
    | { available: true }
    | { available: false; reason: string; remedy: string }
    | { available: 'unknown' };

export interface SmsChannelInputs {
    capabilities?: CampaignCapabilities;
    /** The entitlement the server derives. `undefined` when it could not be read. */
    smsPromotionsEnabled: boolean | undefined;
    /** How many SMS add-ons the practice holds. `undefined` when the add-ons could not be read. */
    smsPromotionsHeld: number | undefined;
    /** Brand registration with the carriers. `undefined` when the server has not said. */
    smsRegistrationApproved?: boolean;
}

/**
 * WHY THE ADD-ON COUNT SEPARATES THE TWO CASES. The entitlement is false both when the practice has not
 * bought SMS and when it has bought it and carrier registration has not completed - promotional SMS
 * ships dark until then, which is correct and is not what this is about. The add-on count is what tells
 * them apart: nothing held means it was never bought; something held with the entitlement still false
 * means the purchase landed and the registration has not.
 */
export const smsChannelAvailability = (
    { smsPromotionsEnabled, smsPromotionsHeld, smsRegistrationApproved, capabilities }: SmsChannelInputs,
): SmsChannelAvailability => {
    if (!capabilities || capabilities.protocolVersion !== 2) return { available: 'unknown' };
    if (!capabilities.implementedChannels.includes('sms')) return { available: false, reason: 'Text campaign execution is unavailable.', remedy: 'Keep the saved text and check again later.' };
    const readiness = capabilities.readiness.sms;
    if (!readiness || readiness.state === 'unknown') return { available: 'unknown' };
    if (readiness.state === 'blocked' && readiness.reason !== 'quiet-hours') return { available: false, reason: readiness.reason ?? 'Text campaign execution is not ready.', remedy: 'Resolve the readiness requirement before sending.' };
    if (smsPromotionsEnabled === undefined) return { available: 'unknown' };
    if (smsRegistrationApproved === false && (smsPromotionsHeld ?? 0) > 0) {
        return {
            available: false,
            reason: 'Text messages are on this practice’s plan, but carrier registration is not finished.',
            remedy: 'Submit the text message registration on the Organization page, then wait for the carriers.',
        };
    }
    if (smsPromotionsEnabled) return { available: true };

    if (smsPromotionsHeld === undefined) {
        return {
            available: false,
            reason: 'This practice cannot send text messages yet.',
            remedy: 'Check SMS messaging on the Subscription page.',
        };
    }

    return smsPromotionsHeld > 0
        ? {
            available: false,
            reason: 'Text messages are on this practice’s plan, but carrier registration is not finished.',
            remedy: 'Texts start sending once the carriers approve the practice. Nothing else is needed here.',
        }
        : {
            available: false,
            reason: 'SMS messaging is not on this practice’s plan, so a text campaign cannot be sent.',
            remedy: 'Add SMS messaging on the Subscription page. Email still sends without it.',
        };
};