// Provides a derived view of the server `GameReport` overlaid with
// the player's local order draft. Every consumer that needs to
// render the player's current intent (inspector, map, mobile sheet)
// subscribes through this context instead of reading `gameState.report`
// directly.
//
// Lifetime matches the in-game shell layout: one source per game,
// rebuilt on layout remount. The source itself is a thin reactive
// wrapper — the actual overlay computation lives in
// `applyOrderOverlay` (api/game-state.ts) and runs lazily on every
// access through the `report` getter.

import {
	applyOrderOverlay,
	type GameReport,
} from "../api/game-state";
import type { GameStateStore } from "./game-state.svelte";
import type { OrderDraftStore } from "../sync/order-draft.svelte";

/**
 * RENDERED_REPORT_CONTEXT_KEY is the Svelte context key the in-game
 * shell layout uses to expose a `RenderedReportSource` instance to
 * descendants. Consumers read the latest overlay through `source.report`
 * (a reactive getter) and re-render when the underlying stores
 * change.
 */
export const RENDERED_REPORT_CONTEXT_KEY = Symbol("rendered-report");

export interface RenderedReportSource {
	readonly report: GameReport | null;
}

/**
 * createRenderedReportSource binds the live `GameStateStore` and
 * `OrderDraftStore` to a getter that returns the overlay-applied
 * report on every read. The getter is reactive: Svelte tracks the
 * underlying `$state` accesses inside `applyOrderOverlay`, so any
 * change to the report or the draft re-runs every dependent
 * `$derived` block.
 *
 * Phase 26: the order draft is composed against the *current* turn,
 * so projecting it onto a historical snapshot would render fictional
 * intent on a past report. In history mode the getter returns the
 * raw server snapshot untouched — the order tab is hidden anyway and
 * mutations are gated at the store, so nothing else needs to know.
 */
export function createRenderedReportSource(
	gameState: GameStateStore,
	orderDraft: OrderDraftStore,
): RenderedReportSource {
	return {
		get report(): GameReport | null {
			const raw = gameState.report;
			if (raw === null) return null;
			if (gameState.historyMode) return raw;
			return applyOrderOverlay(raw, orderDraft.commands, orderDraft.statuses);
		},
	};
}