import { randomUUID } from "node:crypto";
import * as fs from "node:fs";
import * as path from "node:path";
import type { AgentToolResult } from "@earendil-works/pi-agent-core";
import type { ExtensionAPI, ExtensionContext, ToolDefinition } from "@selesai/code";
import { Type } from "typebox";
import {
	SUBAGENT_CHILD_AGENT_ENV,
	SUBAGENT_CHILD_INDEX_ENV,
	SUBAGENT_ORCHESTRATOR_SESSION_ID_ENV,
	SUBAGENT_ORCHESTRATOR_TARGET_ENV,
	SUBAGENT_RUN_ID_ENV,
	SUBAGENT_SUPERVISOR_CHANNEL_DIR_ENV,
} from "../runs/shared/pi-args.ts";
import { POLL_INTERVAL_MS, TEMP_ROOT_DIR, type SubagentState } from "../shared/types.ts";
import { writeAtomicJson } from "../shared/atomic-json.ts";

const SUPERVISOR_CHANNEL_ROOT = path.join(TEMP_ROOT_DIR, "supervisor-channels");
const REQUESTS_DIR = "requests";
const REPLIES_DIR = "replies";
export const NATIVE_SUPERVISOR_TOOL_NAME = "subagent_supervisor";
const MAX_MESSAGE_BYTES = 64 * 1024;
const DEFAULT_ASK_TIMEOUT_MS = 10 * 60 * 1000;
const CHANNEL_POLL_MS = Math.min(POLL_INTERVAL_MS, 500);

type SupervisorReason = "need_decision" | "interview_request" | "progress_update";

interface SupervisorRequest {
	type: "subagent.supervisor.request";
	id: string;
	createdAt: number;
	reason: SupervisorReason;
	message: string;
	expectsReply: boolean;
	orchestratorTarget?: string;
	orchestratorSessionId?: string;
	runId: string;
	agent: string;
	childIndex: number;
	childTarget?: string;
	interview?: unknown;
}

interface PendingSupervisorRequest extends SupervisorRequest {
	channelDir: string;
	requestFile: string;
}

interface SupervisorReply {
	type: "subagent.supervisor.reply";
	requestId: string;
	createdAt: number;
	message: string;
}

interface ContactSupervisorParams {
	reason: SupervisorReason;
	message?: string;
	interview?: unknown;
}

interface IntercomParams {
	action: "list" | "send" | "ask" | "reply" | "pending" | "status";
	to?: string;
	message?: string;
	replyTo?: string;
}

const ContactSupervisorParamsSchema = Type.Object({
	reason: Type.String({ enum: ["need_decision", "interview_request", "progress_update"] }),
	message: Type.Optional(Type.String()),
	interview: Type.Optional(Type.Unsafe({ type: "object", additionalProperties: true })),
}, { additionalProperties: false });

const IntercomParamsSchema = Type.Object({
	action: Type.String({ enum: ["list", "send", "ask", "reply", "pending", "status"] }),
	to: Type.Optional(Type.String()),
	message: Type.Optional(Type.String()),
	replyTo: Type.Optional(Type.String()),
}, { additionalProperties: false });

function safeSegment(value: string): string {
	return value.trim().replace(/[^A-Za-z0-9._-]+/g, "-").replace(/^-+|-+$/g, "") || "unknown";
}

export function resolveSupervisorChannelDir(runId: string, agent: string, childIndex: number): string {
	return path.join(SUPERVISOR_CHANNEL_ROOT, `${safeSegment(runId)}-${safeSegment(agent)}-${childIndex}`);
}

export function ensureSupervisorChannelDir(channelDir: string): void {
	fs.mkdirSync(path.join(channelDir, REQUESTS_DIR), { recursive: true, mode: 0o700 });
	fs.mkdirSync(path.join(channelDir, REPLIES_DIR), { recursive: true, mode: 0o700 });
}

function requestPath(channelDir: string, requestId: string): string {
	return path.join(channelDir, REQUESTS_DIR, `${safeSegment(requestId)}.json`);
}

function replyPath(channelDir: string, requestId: string): string {
	return path.join(channelDir, REPLIES_DIR, `${safeSegment(requestId)}.json`);
}

function readTextEnv(name: string): string | undefined {
	const value = process.env[name]?.trim();
	return value ? value : undefined;
}

function readChildMetadata(): {
	channelDir: string;
	runId: string;
	agent: string;
	childIndex: number;
	orchestratorTarget?: string;
	orchestratorSessionId?: string;
	childTarget?: string;
} | undefined {
	const channelDir = readTextEnv(SUBAGENT_SUPERVISOR_CHANNEL_DIR_ENV);
	const runId = readTextEnv(SUBAGENT_RUN_ID_ENV);
	const agent = readTextEnv(SUBAGENT_CHILD_AGENT_ENV);
	const rawIndex = readTextEnv(SUBAGENT_CHILD_INDEX_ENV);
	const orchestratorSessionId = readTextEnv(SUBAGENT_ORCHESTRATOR_SESSION_ID_ENV);
	if (!channelDir || !runId || !agent || !orchestratorSessionId || rawIndex === undefined || !/^\d+$/.test(rawIndex)) return undefined;
	return {
		channelDir,
		runId,
		agent,
		childIndex: Number(rawIndex),
		orchestratorTarget: readTextEnv(SUBAGENT_ORCHESTRATOR_TARGET_ENV),
		orchestratorSessionId,
		childTarget: readTextEnv("SELESAI_SUBAGENT_INTERCOM_SESSION_NAME"),
	};
}

function reasonHeading(reason: SupervisorReason): string {
	if (reason === "interview_request") return "Subagent requests a structured supervisor interview.";
	if (reason === "progress_update") return "Subagent progress update.";
	return "Subagent needs a supervisor decision.";
}

function formatChildMessage(input: {
	reason: SupervisorReason;
	message?: string;
	interview?: unknown;
	runId: string;
	agent: string;
	childIndex: number;
	childTarget?: string;
}): string {
	const lines = [
		reasonHeading(input.reason),
		`Run: ${input.runId}`,
		`Agent: ${input.agent}`,
		`Child index: ${input.childIndex}`,
	];
	if (input.childTarget) lines.push(`Child intercom target: ${input.childTarget}`);
	lines.push("");
	if (input.message?.trim()) lines.push(input.message.trim());
	if (input.reason === "interview_request") {
		lines.push(
			"",
			"Structured response requested. Reply with JSON, optionally fenced in ```json, matching the requested interview shape.",
		);
		if (input.interview !== undefined) lines.push(JSON.stringify(input.interview, null, "\t"));
	}
	return lines.join("\n").trimEnd();
}

function parseStructuredReply(message: string): { value?: unknown; error?: string } {
	const trimmed = message.trim();
	const fenced = trimmed.match(/^```(?:json)?\s*([\s\S]*?)\s*```$/i)?.[1]?.trim();
	try {
		return { value: JSON.parse(fenced ?? trimmed) };
	} catch (error) {
		return { error: error instanceof Error ? `${error.name}: ${error.message}` : String(error) };
	}
}

function askTimeoutMs(): number {
	const parsed = Number(process.env.PI_INTERCOM_ASK_TIMEOUT_MS);
	return Number.isFinite(parsed) && parsed > 0 ? parsed : DEFAULT_ASK_TIMEOUT_MS;
}

function delay(ms: number, signal?: AbortSignal): Promise<void> {
	return new Promise((resolve, reject) => {
		if (signal?.aborted) {
			reject(new Error("Supervisor request cancelled."));
			return;
		}
		let timer: ReturnType<typeof setTimeout> | undefined;
		const cleanup = () => {
			if (timer) clearTimeout(timer);
			signal?.removeEventListener("abort", onAbort);
		};
		const onAbort = () => {
			cleanup();
			reject(new Error("Supervisor request cancelled."));
		};
		timer = setTimeout(() => {
			cleanup();
			resolve();
		}, ms);
		signal?.addEventListener("abort", onAbort, { once: true });
	});
}

async function waitForReply(channelDir: string, requestId: string, signal?: AbortSignal): Promise<SupervisorReply> {
	const file = replyPath(channelDir, requestId);
	const deadline = Date.now() + askTimeoutMs();
	while (Date.now() <= deadline) {
		if (signal?.aborted) throw new Error("Supervisor request cancelled.");
		if (fs.existsSync(file)) {
			const parsed = JSON.parse(fs.readFileSync(file, "utf-8")) as Partial<SupervisorReply>;
			if (parsed.type === "subagent.supervisor.reply" && parsed.requestId === requestId && typeof parsed.message === "string") {
				return parsed as SupervisorReply;
			}
		}
		await delay(250, signal);
	}
	throw new Error("Timed out waiting for supervisor reply.");
}

async function sendSupervisorRequest(params: ContactSupervisorParams, signal?: AbortSignal): Promise<AgentToolResult<Record<string, unknown>>> {
	const metadata = readChildMetadata();
	if (!metadata) throw new Error("Native supervisor channel is not available for this subagent.");
	if (params.reason !== "progress_update" && !params.message?.trim() && params.reason !== "interview_request") {
		throw new Error("message is required for supervisor decisions.");
	}
	ensureSupervisorChannelDir(metadata.channelDir);
	const requestId = randomUUID();
	const expectsReply = params.reason !== "progress_update";
	const message = formatChildMessage({ ...metadata, reason: params.reason, message: params.message, interview: params.interview });
	const request: SupervisorRequest = {
		type: "subagent.supervisor.request",
		id: requestId,
		createdAt: Date.now(),
		reason: params.reason,
		message,
		expectsReply,
		...(metadata.orchestratorTarget ? { orchestratorTarget: metadata.orchestratorTarget } : {}),
		...(metadata.orchestratorSessionId ? { orchestratorSessionId: metadata.orchestratorSessionId } : {}),
		runId: metadata.runId,
		agent: metadata.agent,
		childIndex: metadata.childIndex,
		...(metadata.childTarget ? { childTarget: metadata.childTarget } : {}),
		...(params.interview !== undefined ? { interview: params.interview } : {}),
	};
	const serialized = JSON.stringify(request, null, "\t");
	if (Buffer.byteLength(serialized, "utf-8") > MAX_MESSAGE_BYTES) throw new Error("Supervisor request is too large.");
	writeAtomicJson(requestPath(metadata.channelDir, requestId), request);

	if (!expectsReply) {
		return {
			content: [{ type: "text", text: "Supervisor progress update queued." }],
			details: { delivered: true, requestId, reason: params.reason },
		};
	}

	const reply = await waitForReply(metadata.channelDir, requestId, signal);
	const details: Record<string, unknown> = { requestId, reason: params.reason };
	if (params.reason === "interview_request") {
		const structured = parseStructuredReply(reply.message);
		if (structured.error) details.structuredReplyParseError = structured.error;
		else details.structuredReply = structured.value;
	}
	return {
		content: [{ type: "text", text: `**Reply from supervisor:**\n${reply.message}` }],
		details,
	};
}

function hasTool(pi: ExtensionAPI, name: string): boolean {
	try {
		return pi.getAllTools?.().some((tool: { name?: unknown }) => tool.name === name) === true;
	} catch {
		return false;
	}
}

export function registerNativeSupervisorClient(pi: ExtensionAPI, options: { includeIntercomFallback?: boolean } = {}): void {
	if (!readChildMetadata()) return;
	const includeIntercomFallback = options.includeIntercomFallback !== false;
	if (!hasTool(pi, "contact_supervisor")) {
		const tool: ToolDefinition<typeof ContactSupervisorParamsSchema, Record<string, unknown>> = {
			name: "contact_supervisor",
			label: "Contact Supervisor",
			description: "Contact the parent/supervisor session for a blocking decision, structured interview, or progress update.",
			parameters: ContactSupervisorParamsSchema,
			execute(_id, params, signal) {
				return sendSupervisorRequest(params as ContactSupervisorParams, signal);
			},
		};
		pi.registerTool(tool);
	}
	if (includeIntercomFallback && !hasTool(pi, "intercom")) {
		const tool: ToolDefinition<typeof IntercomParamsSchema, Record<string, unknown>> = {
			name: "intercom",
			label: "Intercom",
			description: "Native supervisor-channel intercom fallback for subagents. Prefer contact_supervisor when available.",
			parameters: IntercomParamsSchema,
			async execute(_id, params, signal) {
				const action = (params as IntercomParams).action;
				if (action === "status") return { content: [{ type: "text", text: "Native supervisor channel is active." }], details: { active: true } };
				if (action === "list") return { content: [{ type: "text", text: "Supervisor session available through contact_supervisor." }], details: { sessions: [] } };
				if (action === "send") return sendSupervisorRequest({ reason: "progress_update", message: (params as IntercomParams).message ?? "" }, signal);
				if (action === "ask") return sendSupervisorRequest({ reason: "need_decision", message: (params as IntercomParams).message ?? "" }, signal);
				throw new Error("Native child intercom supports status, list, send, and ask. Use parent intercom reply from the supervisor session.");
			},
		};
		pi.registerTool(tool);
	}
}

function parseRequestFile(file: string, channelDir: string): PendingSupervisorRequest | undefined {
	try {
		const parsed = JSON.parse(fs.readFileSync(file, "utf-8")) as Partial<SupervisorRequest>;
		if (parsed.type !== "subagent.supervisor.request") return undefined;
		if (typeof parsed.id !== "string" || !parsed.id) return undefined;
		if (parsed.reason !== "need_decision" && parsed.reason !== "interview_request" && parsed.reason !== "progress_update") return undefined;
		if (typeof parsed.message !== "string" || !parsed.message) return undefined;
		if (typeof parsed.runId !== "string" || typeof parsed.agent !== "string" || typeof parsed.childIndex !== "number") return undefined;
		return { ...parsed as SupervisorRequest, channelDir, requestFile: file };
	} catch {
		return undefined;
	}
}

function listRequestFiles(): Array<{ channelDir: string; file: string }> {
	let channelEntries: fs.Dirent[];
	try {
		channelEntries = fs.readdirSync(SUPERVISOR_CHANNEL_ROOT, { withFileTypes: true });
	} catch (error) {
		if ((error as NodeJS.ErrnoException).code === "ENOENT") return [];
		throw error;
	}
	const files: Array<{ channelDir: string; file: string }> = [];
	for (const entry of channelEntries) {
		if (!entry.isDirectory()) continue;
		const channelDir = path.join(SUPERVISOR_CHANNEL_ROOT, entry.name);
		const requestsDir = path.join(channelDir, REQUESTS_DIR);
		let requestEntries: fs.Dirent[];
		try {
			requestEntries = fs.readdirSync(requestsDir, { withFileTypes: true });
		} catch {
			continue;
		}
		for (const requestEntry of requestEntries) {
			if (requestEntry.isFile() && requestEntry.name.endsWith(".json")) files.push({ channelDir, file: path.join(requestsDir, requestEntry.name) });
		}
	}
	return files;
}

function currentContextSessionId(state: Pick<SubagentState, "currentSessionId">, ctx: ExtensionContext): string | undefined {
	try {
		const sessionId = ctx.sessionManager.getSessionId();
		if (sessionId) return sessionId;
	} catch {
		// Fall through to the last known identity.
	}
	return state.currentSessionId ?? undefined;
}

function requestMatchesContext(request: SupervisorRequest, state: Pick<SubagentState, "currentSessionId">, ctx: ExtensionContext): boolean {
	const currentSessionId = currentContextSessionId(state, ctx);
	return Boolean(currentSessionId && request.orchestratorSessionId === currentSessionId);
}

function formatPendingLine(request: PendingSupervisorRequest): string {
	const replyHint = request.expectsReply ? ` Reply: ${NATIVE_SUPERVISOR_TOOL_NAME}({ action: "reply", replyTo: "${request.id}", message: "..." })` : "";
	return `- ${request.id}: ${request.agent} [${request.runId}#${request.childIndex}] ${request.reason}.${replyHint}`;
}

function requestVisibleText(request: PendingSupervisorRequest): string {
	const lines = [request.message];
	if (request.expectsReply) {
		lines.push("", `Reply with: ${NATIVE_SUPERVISOR_TOOL_NAME}({ action: "reply", replyTo: "${request.id}", message: "..." })`);
	}
	return lines.join("\n");
}

function writeReply(request: PendingSupervisorRequest, message: string): void {
	if (!message.trim()) throw new Error("message is required for supervisor replies.");
	const reply: SupervisorReply = {
		type: "subagent.supervisor.reply",
		requestId: request.id,
		createdAt: Date.now(),
		message: message.trim(),
	};
	writeAtomicJson(replyPath(request.channelDir, request.id), reply);
	try {
		fs.rmSync(request.requestFile, { force: true });
	} catch {
		// Best effort: the reply file is authoritative for the child.
	}
}

function resolvePendingRequest(pending: Map<string, PendingSupervisorRequest>, params: IntercomParams): PendingSupervisorRequest {
	if (params.replyTo) {
		const request = pending.get(params.replyTo);
		if (!request) throw new Error(`No pending supervisor request found for replyTo '${params.replyTo}'.`);
		return request;
	}
	const requests = [...pending.values()].filter((request) => request.expectsReply);
	if (params.to) {
		const normalizedTo = params.to.toLowerCase();
		const matches = requests.filter((request) =>
			request.id.toLowerCase().startsWith(normalizedTo)
			|| request.agent.toLowerCase() === normalizedTo
			|| request.childTarget?.toLowerCase() === normalizedTo,
		);
		if (matches.length === 1) return matches[0]!;
		if (matches.length > 1) throw new Error(`Multiple pending supervisor requests match '${params.to}'. Use replyTo.`);
	}
	if (requests.length === 1) return requests[0]!;
	if (requests.length === 0) throw new Error("No pending supervisor requests need a reply.");
	throw new Error("Multiple pending supervisor requests need replies. Use replyTo.");
}

function publicPendingRequests(pending: Map<string, PendingSupervisorRequest>): Array<Record<string, unknown>> {
	return [...pending.values()].map((request) => ({
		id: request.id,
		runId: request.runId,
		agent: request.agent,
		childIndex: request.childIndex,
		reason: request.reason,
		expectsReply: request.expectsReply,
	}));
}

function buildParentIntercomTool(pending: Map<string, PendingSupervisorRequest>, name = "intercom"): ToolDefinition<typeof IntercomParamsSchema, Record<string, unknown>> {
	return {
		name,
		label: name === "intercom" ? "Intercom" : "Subagent Supervisor",
		description: name === "intercom"
			? "Native pi-subagents supervisor channel. Use reply/pending/status to answer child subagent requests."
			: "Native pi-subagents supervisor channel. Use reply/pending/status to answer child subagent requests without overriding pi-intercom.",
		parameters: IntercomParamsSchema,
		async execute(_id, params) {
			const input = params as IntercomParams;
			if (input.action === "status") {
				return { content: [{ type: "text", text: `Native supervisor channel active. Pending replies: ${pending.size}.` }], details: { active: true, pending: pending.size, root: SUPERVISOR_CHANNEL_ROOT } };
			}
			if (input.action === "pending" || input.action === "list") {
				const lines = [...pending.values()].filter((request) => request.expectsReply).map(formatPendingLine);
				return { content: [{ type: "text", text: lines.length ? lines.join("\n") : "No pending supervisor requests." }], details: { pending: publicPendingRequests(pending) } };
			}
			if (input.action === "reply") {
				const request = resolvePendingRequest(pending, input);
				writeReply(request, input.message ?? "");
				pending.delete(request.id);
				return { content: [{ type: "text", text: `Replied to supervisor request ${request.id}.` }], details: { replyTo: request.id, runId: request.runId, agent: request.agent } };
			}
			if (input.action === "send" || input.action === "ask") {
				throw new Error("Native pi-subagents intercom currently handles supervisor replies. Child agents initiate asks with contact_supervisor.");
			}
			throw new Error(`Unsupported intercom action: ${input.action}`);
		},
	};
}

export function createNativeSupervisorChannel(pi: ExtensionAPI, state: SubagentState): { start: () => void; dispose: () => void; pending: Map<string, PendingSupervisorRequest> } {
	const pending = new Map<string, PendingSupervisorRequest>();
	const seenFiles = new Set<string>();
	let poller: ReturnType<typeof setInterval> | undefined;

	const registerParentTools = (): void => {
		if (!hasTool(pi, NATIVE_SUPERVISOR_TOOL_NAME)) pi.registerTool(buildParentIntercomTool(pending, NATIVE_SUPERVISOR_TOOL_NAME));
		if (!hasTool(pi, "intercom")) pi.registerTool(buildParentIntercomTool(pending));
	};

	const poll = (): void => {
		const ctx = state.lastUiContext;
		if (!ctx) return;
		for (const { channelDir, file } of listRequestFiles()) {
			if (seenFiles.has(file)) continue;
			const request = parseRequestFile(file, channelDir);
			if (!request || !requestMatchesContext(request, state, ctx)) continue;
			seenFiles.add(file);
			if (request.expectsReply) pending.set(request.id, request);
			else {
				try {
					fs.rmSync(request.requestFile, { force: true });
				} catch {
					// Non-blocking progress updates are already delivered to this session.
				}
			}
			pi.sendMessage({
				customType: "subagent_supervisor_request",
				content: requestVisibleText(request),
				display: true,
				details: {
					id: request.id,
					reason: request.reason,
					expectsReply: request.expectsReply,
					runId: request.runId,
					agent: request.agent,
					childIndex: request.childIndex,
				},
			});
		}
	};

	return {
		start: () => {
			if (poller) return;
			registerParentTools();
			poll();
			poller = setInterval(poll, CHANNEL_POLL_MS);
			poller.unref?.();
		},
		dispose: () => {
			if (poller) clearInterval(poller);
			poller = undefined;
			pending.clear();
			seenFiles.clear();
		},
		pending,
	};
}