import * as m from '$lib/paraglide/messages.js';
import type { components } from '$lib/generated/api';

type TimelineEntryDTO = components['schemas']['TimelineEntryDTO'];

/** Styling discriminant for an axis pill/band. */
export type TimelineAccent = 'derived' | 'curated' | 'historical';

export interface AccentConfig {
	/** Visible Unicode glyph — render `aria-hidden`, paired with an sr-only label. */
	glyph: string;
	/** Localized layer/life-event label — used as the sr-only / aria text only. */
	label: string;
	accent: TimelineAccent;
}

/**
 * Maps a timeline EVENT entry to its glyph, redundant non-color label, and accent
 * (REQ-007/008/018). Derived life-events use the * / † / ⚭ glyphs that match
 * `personLifeDates.ts`; HISTORICAL events get the muted world band; everything
 * else (curated PERSONAL) gets the mint family pill.
 */
export function getAccentConfig(entry: TimelineEntryDTO): AccentConfig {
	if (entry.derived) {
		switch (entry.derivedType) {
			case 'BIRTH':
				return { glyph: '*', label: m.timeline_derived_birth(), accent: 'derived' };
			case 'DEATH':
				return { glyph: '†', label: m.timeline_derived_death(), accent: 'derived' };
			case 'MARRIAGE':
				return { glyph: '⚭', label: m.timeline_derived_marriage(), accent: 'derived' };
		}
	}
	if (entry.type === 'HISTORICAL') {
		return { glyph: '◍', label: m.timeline_layer_world(), accent: 'historical' };
	}
	return { glyph: '★', label: m.timeline_layer_family(), accent: 'curated' };
}

/**
 * The curator edit-affordance gate, in one place — the security-relevant contract documented on
 * CLAUDE.md's `TimelineEntryDTO` row (`derived || eventId == null` → no edit link). A curated
 * event's edit pencil shows only for a viewer with WRITE_ALL (`canWrite`), and only when it is a
 * real curated event: never a derived life-event (nothing to edit) and never a null `eventId`.
 * HISTORICAL events are never derived, so this also covers the world band. The gate is UX only —
 * the #781 route guard + backend permission are the real boundary. Shared by EventPill, WorldBand,
 * and EventCluster so the gate has a single source of truth (#850 finding #5).
 */
export function canEditEvent(entry: TimelineEntryDTO, canWrite: boolean): boolean {
	return canWrite && !entry.derived && entry.eventId != null;
}