import type { IDataObject, IExecuteFunctions } from 'n8n-workflow';
import { NodeApiError, NodeOperationError } from 'n8n-workflow';

import type { ConfluenceBodyEnvelope } from './bodyEnvelope';
import { confluenceApiRequest } from '../../transport';

/**
 * Shared fetch → modify → PUT machinery for the Update and Append operations.
 * Confluence uses optimistic locking: every PUT must carry
 * `version.number = current + 1`, so both operations read the page first and
 * a stale number (someone edited in between) surfaces as a 409.
 */

export interface ConfluencePageSnapshot {
	status: 'current' | 'draft';
	title: string;
	versionNumber: number;
	bodyValue: string;
}

export async function fetchPageForWrite(
	this: IExecuteFunctions,
	itemIndex: number,
	pageId: string,
	bodyFormat?: ConfluenceBodyEnvelope['representation'],
): Promise<ConfluencePageSnapshot> {
	const qs: IDataObject = {};
	if (bodyFormat !== undefined) qs['body-format'] = bodyFormat;

	const page = await confluenceApiRequest.call(
		this,
		'GET',
		`/wiki/api/v2/pages/${encodeURIComponent(pageId)}`,
		{},
		qs,
	);

	const status = typeof page.status === 'string' ? page.status : 'unknown';
	if (status !== 'current' && status !== 'draft') {
		throw new NodeOperationError(
			this.getNode(),
			`The page cannot be changed because its status is "${status}"`,
			{
				itemIndex,
				description:
					'Only pages with "current" or "draft" status can be written to. Restore the page in Confluence first, then run this operation again.',
			},
		);
	}

	const versionNumber = (page.version as IDataObject | undefined)?.number;
	if (typeof versionNumber !== 'number') {
		throw new NodeOperationError(this.getNode(), 'Could not read the current version of the page', {
			itemIndex,
		});
	}

	let bodyValue = '';
	if (bodyFormat !== undefined) {
		const bodyEnvelope = (page.body as IDataObject | undefined)?.[bodyFormat] as
			| IDataObject
			| undefined;
		// Empty pages still return value: '' — a missing value must not be
		// mistaken for one, or the write would overwrite the page
		if (typeof bodyEnvelope?.value !== 'string') {
			throw new NodeOperationError(
				this.getNode(),
				'Could not read the current content of the page',
				{
					itemIndex,
					description: `The API response did not include the page body in the "${bodyFormat}" format. The page was not changed.`,
				},
			);
		}
		bodyValue = bodyEnvelope.value;
	}

	return {
		status,
		title: typeof page.title === 'string' ? page.title : '',
		versionNumber,
		bodyValue,
	};
}

export async function putPage(
	this: IExecuteFunctions,
	itemIndex: number,
	pageId: string,
	snapshot: ConfluencePageSnapshot,
	title: string,
	body: ConfluenceBodyEnvelope,
	status: ConfluencePageSnapshot['status'] = snapshot.status,
): Promise<IDataObject> {
	const payload: IDataObject = {
		id: pageId,
		status,
		title,
		body,
		// Drafts are single-version and require version 1; only published-to-published
		// writes increment. See https://developer.atlassian.com/cloud/confluence/rest/v2/api-group-page/#api-pages-id-put
		version: {
			number: status === 'draft' || snapshot.status === 'draft' ? 1 : snapshot.versionNumber + 1,
		},
	};

	try {
		return await confluenceApiRequest.call(
			this,
			'PUT',
			`/wiki/api/v2/pages/${encodeURIComponent(pageId)}`,
			payload,
		);
	} catch (error) {
		if (error instanceof NodeApiError && error.httpCode === '409') {
			throw new NodeOperationError(this.getNode(), 'The page was modified concurrently', {
				itemIndex,
				description:
					'Someone else changed the page between this operation reading it and saving it. Nothing was overwritten — run the node again to apply the change to the latest version of the page.',
			});
		}
		throw error;
	}
}