import type { ExtensionContext } from "@earendil-works/pi-coding-agent";
import type { NotebookControlResult, ToolExecutionContext } from "../code-mode/types.ts";
import { globMatcher } from "./glob.ts";
import type { DenoJupyterKernel } from "./jupyter-kernel.ts";
import { resolveNotebookProject } from "./project-identity.ts";
import {
	listNotebookProfiles,
	loadNotebookProfile,
	NotebookProfileRestoreError,
	saveNotebookProfile,
} from "./profile-state.ts";
import type { ProfileStateSummary } from "./profile-state-format.ts";

const MESSAGE_BUDGET = 16 * 1024;

interface NotebookProfileHost {
	kernel(): DenoJupyterKernel | undefined;
	activeCellId(): string | undefined;
	checkpoint(): Promise<void>;
	markChanged(): void;
	baselineNames(): ReadonlySet<string>;
	profileStorage(): { agentDir: string; maxBytes: number };
	rollback(context: ExtensionContext): Promise<void>;
}

export class NotebookProfileController {
	private readonly host: NotebookProfileHost;

	constructor(host: NotebookProfileHost) {
		this.host = host;
	}

	list(query: string | undefined): NotebookControlResult {
		const storage = this.host.profileStorage();
		const matches = query === undefined ? undefined : globMatcher(query);
		const profiles = listNotebookProfiles(storage.agentDir)
			.filter(({ name }) => !matches || matches(name));
		return {
			message: formatProfiles(profiles, query),
			details: { profiles, ...(query === undefined ? {} : { query }) },
		};
	}

	async save(name: string, context: ToolExecutionContext, signal?: AbortSignal): Promise<NotebookControlResult> {
		const activeCell = this.host.activeCellId();
		if (activeCell) throw new Error(`Cannot save a notebook profile while exec cell "${activeCell}" is running`);
		const storage = this.host.profileStorage();
		await this.host.checkpoint();
		const summary = await saveNotebookProfile({
			name,
			kernel: this.host.kernel()!,
			project: resolveNotebookProject(context.cwd),
			agentDir: storage.agentDir,
			baselineNames: this.host.baselineNames(),
			maxBytes: storage.maxBytes,
			signal,
		});
		return {
			message: `Saved notebook profile ${summary.name}: ${summary.values} value(s), ${summary.definitions} definition(s), ${summary.skipped} skipped`,
			details: { ...summary },
		};
	}

	async load(name: string, context: ToolExecutionContext, signal?: AbortSignal): Promise<NotebookControlResult> {
		const activeCell = this.host.activeCellId();
		if (activeCell) throw new Error(`Cannot load a notebook profile while exec cell "${activeCell}" is running`);
		const storage = this.host.profileStorage();
		await this.host.checkpoint();
		let loaded;
		try {
			loaded = await loadNotebookProfile({
				name,
				kernel: this.host.kernel()!,
				agentDir: storage.agentDir,
				baselineNames: this.host.baselineNames(),
				maxBytes: storage.maxBytes,
				signal,
			});
		} catch (error) {
			if (error instanceof NotebookProfileRestoreError) {
				const extension = context.extensionContext;
				if (extension) await this.host.rollback(extension);
			}
			throw error;
		}
		if (loaded.collisions.length > 0) {
			throw new Error(`Notebook profile ${name} conflicts with existing bindings: ${bound(loaded.collisions.join(", "))}. Release or rename them before loading`);
		}
		if (loaded.loaded.length > 0) {
			this.host.markChanged();
			await this.host.checkpoint();
		}
		return {
			message: `Loaded notebook profile ${name}: ${loaded.summary.values} value(s), ${loaded.summary.definitions} definition(s)`,
			details: loaded,
		};
	}
}

function formatProfiles(profiles: ProfileStateSummary[], query: string | undefined): string {
	if (profiles.length === 0) return query === undefined ? "No notebook profiles saved" : `No notebook profiles match ${JSON.stringify(query)}`;
	return bound([
		`Notebook profiles${query === undefined ? "" : ` matching ${JSON.stringify(query)}`}:`,
		...profiles.map((profile) => `- ${profile.name}: ${profile.values} value(s), ${profile.definitions} definition(s), saved ${profile.createdAt}`),
	].join("\n"));
}

function bound(value: string): string {
	const marker = "\n[Notebook profile output truncated; narrow query]";
	return value.length <= MESSAGE_BUDGET ? value : `${value.slice(0, MESSAGE_BUDGET - marker.length)}${marker}`;
}