import type { Campaign, CampaignCounts, CampaignDelivery } from '../../../services/CampaignService';

//
// S4e-1 - turning campaign counters into an HONEST report.
//
// THE WHOLE POINT OF THIS MODULE IS THAT ABSENT IS NOT ZERO. A campaign sent before S4e-1 shipped
// carries no SES message tags and will never receive a delivery event. Rendering it "0 delivered"
// asserts that its mail did not land, when the truth is that we never measured - the same false
// assertion class as reference-authz-denial-never-renders-as-empty-data.
//
// NEVER write `counts.delivered ?? 0` anywhere in this file or its consumers. That single
// expression is the bug this module exists to prevent, and it looks completely reasonable.
//

export type TrackingVerdict =
    | { kind: 'untracked' }
    | { kind: 'full' }
    | { kind: 'partial'; tracked: number; sent: number };

/**
 * How much of this campaign's delivery we can actually speak to.
 *
 * `partial` is not hypothetical: a campaign parked in `sending` across the S4e-1 deploy has some
 * recipients tagged and some not, so its delivery figures are a FLOOR. Presence of the counter
 * cannot detect that - only the denominator can.
 */
export function describeTracking(counts: CampaignCounts): TrackingVerdict {
    const tracked = counts.trackedSends;
    if (tracked === undefined || tracked === 0) return { kind: 'untracked' };
    if (tracked >= counts.sent) return { kind: 'full' };
    return { kind: 'partial', tracked, sent: counts.sent };
}

const DELIVERY_ROWS: { label: string; key: keyof CampaignDelivery }[] = [
    { label: 'Delivered', key: 'delivered' },
    { label: 'Bounced', key: 'bounced' },
    { label: 'Spam complaints', key: 'complained' },
    { label: 'Unsubscribed', key: 'unsubscribed' },
    // S4e-2
    { label: 'Clicked', key: 'clicked' },
    { label: 'Booked', key: 'booked' },
];

export function reportRows(
    counts: CampaignCounts, delivery: CampaignDelivery | null | undefined,
): { label: string; value: number }[] {
    const rows = [
        { label: 'Sent', value: counts.sent },
        { label: 'Failed', value: counts.failed },
        { label: 'Suppressed', value: counts.suppressed },
    ];

    // `null` MEANS NO DELIVERY ROW EXISTS (the campaign was never tracked); `undefined` means
    // THIS RESPONSE never carried the field at all (final fix wave, CRITICAL 2 - only `GET /{id}`
    // attaches `delivery`; send/schedule/cancel/list/post/put don't). Both honestly mean "no
    // measurement on this payload", and neither is zero, so they're deliberately handled alike here
    // with `==` rather than `===` - this is the one spot in this file where loose equality is
    // correct, not sloppy. Returning early with no delivery rows is the honest answer either way.
    // Never `delivery ?? {}`: that turns "never measured" into "measured, all absent", which
    // reads on screen as though the mail simply never arrived.
    if (delivery == null) return rows;

    for (const { label, key } of DELIVERY_ROWS) {
        const value = delivery[key];
        // `!== undefined`, never `??`. A tracked campaign with genuinely zero deliveries MUST show
        // "Delivered 0"; a counter that never fired must show no row. `?? 0` collapses those two.
        if (value !== undefined) rows.push({ label, value });
    }

    // SURFACED, NEVER CLAMPED (spec §3). More deliveries than sends is impossible and means a
    // real bug - most likely dedup failing. Clamping would destroy the only evidence, so the numbers
    // are reported exactly as stored and the anomaly is announced where a developer will find it.
    if (delivery.delivered !== undefined && delivery.delivered > counts.sent) {
        console.warn(
            `CAMPAIGN_REPORT_IMPOSSIBLE_COUNTS: delivered=${delivery.delivered} exceeds sent=${counts.sent}`,
        );
    }

    return rows;
}

export function campaignReportRows(campaign: Campaign): { label: string; value: number | string }[] {
    if (campaign.protocolVersion !== 2) return reportRows(campaign.counts, campaign.delivery);
    const rows: { label: string; value: number | string }[] = [];
    const requested = campaign.channels.filter((channel): channel is 'email' | 'sms' => channel === 'email' || channel === 'sms');
    let knownMessages = 0;
    let allKnown = true;
    for (const channel of requested) {
        const label = channel === 'email' ? 'Email' : 'SMS';
        const counts = campaign.channelCounts?.[channel];
        const delivery = campaign.channelDelivery?.[channel];
        for (const [key, caption] of [
            ['accepted', 'accepted'], ['failedBeforeAcceptance', 'failed before acceptance'],
            ['suppressed', 'suppressed'], ['unknown', 'send outcome unknown'], ['owed', 'dispatch owed'],
        ] as const) {
            rows.push({ label: `${label} ${caption}`, value: counts?.[key] ?? 'Unavailable' });
        }
        if (counts?.accepted === undefined) allKnown = false;
        else knownMessages += counts.accepted;
        if (channel === 'sms') {
            for (const [key, caption] of [['delivered', 'delivery confirmed'], ['failed', 'terminal undelivered'], ['pending', 'delivery pending'], ['unknown', 'delivery unknown']] as const) {
                rows.push({ label: `SMS ${caption}`, value: delivery?.[key] ?? 'Unavailable' });
            }
        } else {
            for (const [key, caption] of [['delivered', 'delivered'], ['bounced', 'bounced'], ['complained', 'spam complaints'], ['unsubscribed', 'unsubscribed']] as const) {
                if (delivery?.[key] !== undefined) rows.push({ label: `Email ${caption}`, value: delivery[key]! });
            }
            rows.push({ label: 'Email delivery tracking coverage', value: counts?.accepted === undefined || counts.trackedSends === undefined
                ? 'Unavailable' : `${counts.trackedSends} of ${counts.accepted} accepted email messages` });
        }
    }
    rows.push({ label: 'Accepted messages total', value: allKnown ? knownMessages : 'Unavailable' });
    rows.push({ label: 'Matched people', value: campaign.execution?.matchedPeople ?? 'Unavailable' });
    if (campaign.execution?.continuation && campaign.execution.legacyCounts) {
        for (const row of reportRows(campaign.execution.legacyCounts, undefined)) {
            rows.push({ label: `Historical email ${row.label.toLowerCase()}`, value: row.value });
        }
    }
    for (const [key, label] of [['clicked', 'Campaign link clicks'], ['booked', 'Campaign bookings']] as const) {
        if (campaign.delivery?.[key] !== undefined) rows.push({ label, value: campaign.delivery[key]! });
    }
    return rows;
}

export function campaignDispatchComplete(campaign: Campaign): boolean {
    if (campaign.protocolVersion !== 2) return campaign.status === 'sent';
    return campaign.channels.length > 0 && campaign.channels.every((channel) =>
        (channel === 'email' || channel === 'sms') && campaign.execution?.legs?.[channel]?.state === 'dispatch-complete'
        && campaign.channelCounts?.[channel]?.owed === 0 && campaign.channelCounts?.[channel]?.unknown === 0);
}

/** Dispatch evidence only; provider delivery remains a separate report. */
export function campaignDispatchSummary(campaign: Campaign): string {
    const requested = campaign.channels.filter((channel): channel is 'email' | 'sms' => channel === 'email' || channel === 'sms');
    const details = requested.map(channel => {
        const counts = campaign.channelCounts?.[channel];
        const values = [
            ['accepted', 'accepted'], ['failedBeforeAcceptance', 'failed before acceptance'],
            ['suppressed', 'suppressed'], ['unknown', 'send outcome unknown'], ['owed', 'dispatch owed'],
        ] as const;
        const state = campaign.execution?.legs?.[channel]?.state;
        return `${channel === 'email' ? 'Email' : 'SMS'}${state && state !== 'dispatch-complete' ? ` (${state})` : ''}: `
            + values.map(([key, label]) => `${counts?.[key] ?? 'unavailable'} ${label}`).join(', ') + '.';
    });
    if (campaign.execution?.continuation && campaign.execution.legacyCounts) {
        const counts = campaign.execution.legacyCounts;
        details.push(`Historical email: ${counts.sent} sent, ${counts.failed} failed, ${counts.suppressed} suppressed. Historical recipient outcomes remain unresolved.`);
    }
    return details.join(' ');
}