import type { CliConfig } from './config.ts';

/**
 * Talks to the schulcloud-mcp server's /api surface.
 *
 * Deliberately the only thing in the CLI that knows a network exists, and it
 * never touches Schulcloud directly — the Pi holds that credential.
 */

export interface ManifestEntry {
	fileId: string;
	name: string;
	path: string;
	size: number;
	mimeType: string;
	courseId: string | null;
	courseTitle: string;
	status: 'added' | 'unchanged' | 'removed';
}

export interface Manifest {
	crawlId: number;
	cursor: string;
	crawledAt?: string;
	count: number;
	entries: ManifestEntry[];
}

/** One entry of a file-manager tree or search, as /api/fs returns it. */
export interface FsEntry {
	type: 'directory' | 'file';
	path: string;
	parentPath: string;
	depth: number;
	id: string;
	name: string;
	size?: number;
	mimeType?: string | null;
	blocked?: boolean;
}

export interface FsListing {
	path: string;
	kind: 'directory' | 'file';
	area?: string | null;
	directories?: { id: string; name: string; path: string }[];
	files?: { id: string; name: string; path: string; size: number; mimeType?: string; blocked: boolean }[];
	file?: { id: string; name: string; size: number; mimeType?: string; blocked: boolean };
}

export interface FsWalk {
	path: string;
	kind: 'directory' | 'file';
	entries?: FsEntry[];
	matches?: FsEntry[];
	file?: FsListing['file'];
	visited?: number;
	truncated?: boolean;
	failures?: { path: string; reason: string }[];
}

/** The server's Schulcloud token, as `/api/token` reports it — never the token itself. */
export interface TokenInfo {
	expiresAt?: string;
	daysLeft?: number;
	source: string;
	persistent: boolean;
	keepalive: { running: boolean; budgetSeconds?: number; lastExtendedAt?: string; rejectedAt?: string } | null;
}

export class ApiError extends Error {
	readonly status: number;

	constructor(status: number, message: string) {
		super(message);
		this.status = status;
		this.name = 'ApiError';
	}
}

export class ApiClient {
	private readonly config: CliConfig;

	constructor(config: CliConfig) {
		this.config = config;
	}

	private async request(path: string, init: RequestInit = {}): Promise<Response> {
		const response = await fetch(`${this.config.server}${path}`, {
			...init,
			headers: { ...(init.headers ?? {}), Authorization: `Bearer ${this.config.token}` },
		});
		if (!response.ok) {
			let detail = '';
			try {
				const body = (await response.json()) as { message?: string; error?: string };
				detail = body.message ?? body.error ?? '';
			} catch {
				// Non-JSON error bodies are not worth surfacing verbatim.
			}
			throw new ApiError(response.status, describe(response.status, detail, this.config.server));
		}
		return response;
	}

	async status(): Promise<Record<string, unknown>> {
		return (await (await this.request('/api/status')).json()) as Record<string, unknown>;
	}

	async token(): Promise<TokenInfo> {
		return (await (await this.request('/api/token')).json()) as TokenInfo;
	}

	/** Hands the server a fresh Schulcloud token; it checks the token before using it. */
	async replaceToken(jwt: string): Promise<TokenInfo & { changed: boolean; persisted: boolean }> {
		const response = await this.request('/api/token', {
			method: 'PUT',
			headers: { 'content-type': 'application/json' },
			body: JSON.stringify({ jwt }),
		});
		return (await response.json()) as TokenInfo & { changed: boolean; persisted: boolean };
	}

	async manifest(since?: string): Promise<Manifest> {
		const query = since ? `?since=${encodeURIComponent(since)}` : '';
		return (await (await this.request(`/api/manifest${query}`)).json()) as Manifest;
	}

	/**
	 * Starts a re-crawl and waits for it by polling the server's status.
	 *
	 * Not one long request: a crawl that downloads every course file can run for
	 * many minutes, and fetch gives up after five without response headers —
	 * which reported "fetch failed" for a crawl that was succeeding.
	 */
	async refresh(
		courseId?: string,
		force = false,
		onWaiting?: (seconds: number) => void,
	): Promise<Record<string, unknown>> {
		const response = await this.request('/api/refresh', {
			method: 'POST',
			headers: { 'content-type': 'application/json' },
			body: JSON.stringify({ courseId, force, wait: false }),
		});
		const started = (await response.json()) as { joined?: boolean; startedAt?: string | null };
		const began = Date.now();

		for (;;) {
			await new Promise((resolve) => setTimeout(resolve, 3000));
			const status = (await this.status()) as {
				indexer?: { running?: boolean; lastResult?: Record<string, unknown>; lastError?: string } | null;
			};
			const indexer = status.indexer;
			if (!indexer) throw new ApiError(503, 'The server has no indexer.');
			if (indexer.running) {
				onWaiting?.(Math.round((Date.now() - began) / 1000));
				continue;
			}
			if (indexer.lastError) throw new ApiError(502, `The re-crawl failed on the server: ${indexer.lastError}`);
			if (!indexer.lastResult) throw new ApiError(502, 'The re-crawl finished without a result.');
			return { ...indexer.lastResult, joined: started.joined === true };
		}
	}

	/** Streams one file's bytes. */
	async file(fileId: string): Promise<Response> {
		return this.request(`/api/files/${encodeURIComponent(fileId)}`);
	}

	// --- the file manager ------------------------------------------------------

	async fsList(path: string): Promise<FsListing> {
		return (await (await this.request(`/api/fs/list?${new URLSearchParams({ path })}`)).json()) as FsListing;
	}

	async fsTree(path: string, depth: number, maxFolders: number): Promise<FsWalk> {
		const query = new URLSearchParams({ path, depth: String(depth), maxFolders: String(maxFolders) });
		return (await (await this.request(`/api/fs/tree?${query}`)).json()) as FsWalk;
	}

	async fsFind(name: string, path: string, type: string, maxFolders: number): Promise<FsWalk> {
		const query = new URLSearchParams({ name, path, type, maxFolders: String(maxFolders) });
		return (await (await this.request(`/api/fs/find?${query}`)).json()) as FsWalk;
	}

	/** Streams one file-manager file's bytes, by path or by id. */
	async fsFile(target: { path: string } | { id: string; name: string }): Promise<Response> {
		const query = 'path' in target ? new URLSearchParams({ path: target.path }) : new URLSearchParams(target);
		return this.request(`/api/fs/file?${query}`);
	}
}

function describe(status: number, detail: string, server: string): string {
	if (status === 401) return `Unauthorized — the token is wrong or expired. Re-run: schulcloud login --server ${server} --token <token>`;
	if (status === 503) return 'The server is running without an index, so this command is unavailable. Set DATABASE_URL on the server.';
	if (status === 409) return detail || 'The sync cursor is unknown to the server. Run a full sync with --full.';
	if (status === 429) return detail || 'Refreshed too recently — wait a moment, or pass --force.';
	// The file manager's own errors already say what was not found and what is there.
	if ((status === 400 || status === 404 || status === 422) && detail) return detail;
	return detail ? `HTTP ${status}: ${detail}` : `HTTP ${status}`;
}