// S1 - mirrors aws/sam/services/api/src/utils/appointmentReminderPolicy.ts.
// Keep the type and the defaults in step with the server copy, exactly as
// config/communicationPreferences.ts mirrors its server twin. Divergence here means the editor
// offers values the server rejects.

import type { Organization } from 'fhir/r4';

export interface QuietHours {
    start: string;
    end: string;
    behavior: 'defer' | 'suppress';
}

export interface ReminderPolicy {
    enabled: boolean;
    offsetsMinutes: number[];
    maxPerAppointment: number;
    quietHours: QuietHours | null;
}

export const MAX_OFFSET_MINUTES = 10080;

export const DEFAULT_REMINDER_POLICY: ReminderPolicy = {
    enabled: false,
    offsetsMinutes: [120, 1440],
    maxPerAppointment: 2,
    quietHours: null,
};

/** Offsets the editor offers. Every value must be one the server's validator accepts. */
export const OFFSET_PRESETS = [60, 120, 240, 1440, 2880, 4320, 10080];

export function formatOffset(minutes: number): string {
    if (minutes % 1440 === 0) {
        const days = minutes / 1440;
        return `${days} ${days === 1 ? 'day' : 'days'} before`;
    }
    if (minutes % 60 === 0) {
        const hours = minutes / 60;
        return `${hours} ${hours === 1 ? 'hour' : 'hours'} before`;
    }
    return `${minutes} minutes before`;
}

// There is no GET /R4/appointment-reminder-settings - the org's saved policy travels only on the
// Organization resource, as this extension. The server WRITES this exact URL (setReminderPolicy in
// its own copy of this file); the plugin READS it back here, so the literal MUST match byte for byte.
export const ORG_APPOINTMENT_REMINDER_EXTENSION_URL =
    'https://akashichealthrecords.com/fhir/StructureDefinition/organization-appointment-reminder-policy';

/**
 * Pure reader - mirrors the server's resolveEffectiveReminderPolicy exactly (same extension URL,
 * same child urls), so the editor seeds from whatever the org last saved. Falls back to
 * DEFAULT_REMINDER_POLICY when the org has never saved a policy, same as the server default.
 */
export function resolveOrgReminderPolicy(organization?: Organization | null): ReminderPolicy {
    const ext = organization?.extension?.find((e) => e.url === ORG_APPOINTMENT_REMINDER_EXTENSION_URL);
    if (!ext) return { ...DEFAULT_REMINDER_POLICY, offsetsMinutes: [...DEFAULT_REMINDER_POLICY.offsetsMinutes] };

    const children = ext.extension ?? [];
    const offsets = children
        .filter((c) => c.url === 'offsetMinutes')
        .map((c) => c.valueInteger)
        .filter((v): v is number => typeof v === 'number')
        .sort((a, b) => a - b);

    const quietExt = children.find((c) => c.url === 'quietHours');
    const quietChildren = quietExt?.extension ?? [];
    const start = quietChildren.find((c) => c.url === 'start')?.valueString;
    const end = quietChildren.find((c) => c.url === 'end')?.valueString;
    const behavior = quietChildren.find((c) => c.url === 'behavior')?.valueString;

    return {
        enabled: children.find((c) => c.url === 'enabled')?.valueBoolean ?? DEFAULT_REMINDER_POLICY.enabled,
        offsetsMinutes: offsets.length ? offsets : [...DEFAULT_REMINDER_POLICY.offsetsMinutes],
        maxPerAppointment:
            children.find((c) => c.url === 'maxPerAppointment')?.valueInteger ?? DEFAULT_REMINDER_POLICY.maxPerAppointment,
        quietHours:
            start && end && (behavior === 'defer' || behavior === 'suppress')
                ? { start, end, behavior }
                : null,
    };
}