import type { ExtensionAPI, ExtensionContext } from "@earendil-works/pi-coding-agent";
import { SettingsManager, getAgentDir } from "@earendil-works/pi-coding-agent";
import {
	effectiveIntegration,
	type ReinjectDeliveryMode,
	type SkillReinjectSettings,
} from "./settings";
import type { AutoCompactIntegration, RuntimeFlags } from "./state";

/** Detect @capyup/pi-auto-compact via public getCommands API (SPEC §16.4). */
export function detectPiAutoCompact(pi: ExtensionAPI): boolean {
	return pi.getCommands().some((command) => command.name === "auto-compact");
}

/** Detect pi-auto-compact and cache result in runtime flags (SPEC §16.4). */
export function detectAndCachePiAutoCompact(pi: ExtensionAPI, runtime: RuntimeFlags): boolean {
	runtime.autoCompactDetected = detectPiAutoCompact(pi);
	return runtime.autoCompactDetected;
}

/** Resolve re-inject delivery mode from settings, detect cache, and session override (SPEC §6.5.3). */
export function resolveDeliveryMode(
	settings: SkillReinjectSettings,
	runtime: RuntimeFlags,
	sessionIntegrationOverride?: AutoCompactIntegration | null,
): ReinjectDeliveryMode {
	return effectiveIntegration(settings, runtime.autoCompactDetected, sessionIntegrationOverride);
}

/** pi-auto-compact follow-up message prefixes (SPEC §16.9); documentation/tests only, not runtime v1. */
export const PI_AUTO_COMPACT_FOLLOW_UP_PREFIXES = [
	"Auto-compact ran before this turn.",
	"Auto-compact ran mid-turn.",
	"Emergency auto-compact ran.",
	"Auto-compact ran on session resume.",
] as const;

const PI_DEFAULT_COMPACTION_ENABLED = true;

function readCompactionEnabled(settings: object): boolean | undefined {
	const compaction = (settings as Record<string, unknown>).compaction;
	if (!compaction || typeof compaction !== "object" || Array.isArray(compaction)) {
		return undefined;
	}
	const enabled = (compaction as Record<string, unknown>).enabled;
	return typeof enabled === "boolean" ? enabled : undefined;
}

/** Merged Pi compaction.enabled with project-over-global semantics (SPEC §16.7). */
export function resolvePiDefaultCompactionEnabled(
	globalSettings: object,
	projectSettings: object,
): boolean {
	return (
		readCompactionEnabled(projectSettings) ??
		readCompactionEnabled(globalSettings) ??
		PI_DEFAULT_COMPACTION_ENABLED
	);
}

export function isPiDefaultCompactionEnabled(ctx: ExtensionContext): boolean {
	const manager = SettingsManager.create(ctx.cwd, getAgentDir(), {
		projectTrusted: ctx.isProjectTrusted(),
	});
	return resolvePiDefaultCompactionEnabled(
		manager.getGlobalSettings(),
		manager.getProjectSettings(),
	);
}

/** One-time ui.notify when Pi default compaction and pi-auto-compact are both active (SPEC §16.7). */
export function maybeNotifyCompactionCoexistenceHint(
	ctx: ExtensionContext,
	runtime: RuntimeFlags,
	piDefaultCompactionEnabled = isPiDefaultCompactionEnabled(ctx),
): void {
	if (runtime.compactionCoexistenceHintShown || !runtime.autoCompactDetected) {
		return;
	}
	if (!piDefaultCompactionEnabled) {
		return;
	}
	if (ctx.hasUI) {
		ctx.ui.notify(
			"Pi built-in auto-compaction and pi-auto-compact are both enabled. Consider setting compaction.enabled to false in settings.json.",
			"info",
		);
	}
	runtime.compactionCoexistenceHintShown = true;
}