import { GENERIC_RESOURCE_LABEL, resourceLabel } from './resourceLabel';

// / My History - say WHAT HAPPENED as well as what it happened to.
//
// The feed rendered every non-access row as "updated", because the row's kind was the only thing
// consulted and the kind does not carry the verb. So a creation - the commonest change in a live record,
// and the only one an order or a new note can be - told the patient their record had been CHANGED. On the
// one screen built so somebody can judge whether what happened to their record should have happened,
// "your clinician altered something about you" and "your clinician ordered you a test" are not
// interchangeable sentences, and only the second one is true of a create.
//
// The verb comes from the FHIR AuditEvent action the server already sends. It is not inferred from
// whether a previous version can be found: an absent history is a fact about what this client could
// read, never a fact about what the clinician did.
const VERBS: Readonly<Record<string, string>> = {
    C: 'added',
    U: 'updated',
    D: 'removed',
};

// UNKNOWN IS ITS OWN CASE, and it says less rather than guessing. `R` never reaches here (reads are
// access rows) and `E` is an execute the change branch catches by falling through, so an action this
// map does not name is one nobody has classified. "changed" is true of a create, an update and a delete
// alike, which is exactly the claim the evidence supports when the action is missing or unrecognised.
// Defaulting to "updated" instead would reintroduce the defect for every row the map has not caught up
// with, which is how the original wording came to be wrong in the first place.
const UNKNOWN_VERB = 'changed';

// A REFUSED ATTEMPT IS NOT A CHANGE, AND IT IS NOT NOTHING EITHER. The row stays - section 7 of the design:
// this feed must never show less than the truth - but it says the attempt did not go through. FHIR
// AuditEvent outcome: "0" success; "4", "8", "12" failures of rising severity. Absent is treated as
// success, the reading every older row has always had.
const INFINITIVES: Readonly<Record<string, string>> = {
    C: 'add',
    U: 'update',
    D: 'remove',
};
export const DID_NOT_GO_THROUGH = 'it did not go through';

// The generic label needs a different SENTENCE, not a different word. "updated your record" is English;
// "added your record" is not, and "removed your record" is alarming as well as untrue - the record is
// not what was removed, something in it was. So the unmapped case gets a phrasing that keeps the verb
// honest while staying vague about the noun, which is all this client knows.
const GENERIC_PHRASES: Readonly<Record<string, string>> = {
    C: `added something to ${GENERIC_RESOURCE_LABEL}`,
    U: `updated ${GENERIC_RESOURCE_LABEL}`,
    D: `removed something from ${GENERIC_RESOURCE_LABEL}`,
};

/**
 * The verb phrase for one change row: what was done, and to what, in the patient's own words.
 *
 * `action` is the FHIR AuditEvent action code; `resourceType` is the raw type, which is mapped to
 * patient language by `resourceLabel` and NEVER rendered as itself.
 */
export const describeChange = (
    action: string | undefined,
    resourceType: string | undefined,
    outcome?: string | undefined,
): string => {
    const label = resourceLabel(resourceType);
    const verb = (action && VERBS[action]) || UNKNOWN_VERB;

    if (outcome !== undefined && outcome !== '0') {
        const attempted = (action && INFINITIVES[action]) || 'change';
        return `tried to ${attempted} ${label} - ${DID_NOT_GO_THROUGH}`;
    }

    if (label === GENERIC_RESOURCE_LABEL) {
        return (action && GENERIC_PHRASES[action]) || `changed ${GENERIC_RESOURCE_LABEL}`;
    }

    return `${verb} ${label}`;
};