/*---------------------------------------------------------------------------------------------
 *  Copyright (c) Microsoft Corporation. All rights reserved.
 *  Licensed under the MIT License. See License.txt in the project root for license information.
 *--------------------------------------------------------------------------------------------*/

import * as path from 'path';
import * as vscode from 'vscode';
import * as URI from 'vscode-uri';
import { coalesce } from '../../util/arrays';
import { getDocumentDir } from '../../util/document';
import { mediaMimes } from '../../util/mimes';
import { Schemes } from '../../util/schemes';
import { NewFilePathGenerator } from './copyFiles';

enum MediaKind {
	Image,
	Video,
	Audio,
}

export const externalUriSchemes = [
	'http',
	'https',
	'mailto',
];

export const mediaFileExtensions = new Map<string, MediaKind>([
	// Images
	['bmp', MediaKind.Image],
	['gif', MediaKind.Image],
	['ico', MediaKind.Image],
	['jpe', MediaKind.Image],
	['jpeg', MediaKind.Image],
	['jpg', MediaKind.Image],
	['png', MediaKind.Image],
	['psd', MediaKind.Image],
	['svg', MediaKind.Image],
	['tga', MediaKind.Image],
	['tif', MediaKind.Image],
	['tiff', MediaKind.Image],
	['webp', MediaKind.Image],

	// Videos
	['ogg', MediaKind.Video],
	['mp4', MediaKind.Video],

	// Audio Files
	['mp3', MediaKind.Audio],
	['aac', MediaKind.Audio],
	['wav', MediaKind.Audio],
]);

const smartPasteRegexes = [
	{ regex: /(\[[^\[\]]*](?:\([^\(\)]*\)|\[[^\[\]]*]))/g }, // In a Markdown link
	{ regex: /^```[\s\S]*?```$/gm }, // In a backtick fenced code block
	{ regex: /^~~~[\s\S]*?~~~$/gm }, // In a tildefenced code block
	{ regex: /^\$\$[\s\S]*?\$\$$/gm }, // In a fenced math block
	{ regex: /`[^`]*`/g }, // In inline code
	{ regex: /\$[^$]*\$/g }, // In inline math
];

export interface SkinnyTextDocument {
	offsetAt(position: vscode.Position): number;
	getText(range?: vscode.Range): string;
	readonly uri: vscode.Uri;
}

export enum PasteUrlAsFormattedLink {
	Always = 'always',
	Smart = 'smart',
	Never = 'never'
}

export function getPasteUrlAsFormattedLinkSetting(document: vscode.TextDocument): PasteUrlAsFormattedLink {
	return vscode.workspace.getConfiguration('markdown', document).get<PasteUrlAsFormattedLink>('editor.pasteUrlAsFormattedLink.enabled', PasteUrlAsFormattedLink.Smart);
}

export async function createEditAddingLinksForUriList(
	document: SkinnyTextDocument,
	ranges: readonly vscode.Range[],
	urlList: string,
	isExternalLink: boolean,
	useSmartPaste: boolean,
	token: vscode.CancellationToken,
): Promise<{ additionalEdits: vscode.WorkspaceEdit; label: string; markdownLink: boolean } | undefined> {

	if (ranges.length === 0) {
		return;
	}
	const edits: vscode.SnippetTextEdit[] = [];
	let placeHolderValue: number = ranges.length;
	let label: string = '';
	let pasteAsMarkdownLink: boolean = true;
	let markdownLink: boolean = true;

	for (const range of ranges) {
		const selectedRange: vscode.Range = new vscode.Range(
			new vscode.Position(range.start.line, document.offsetAt(range.start)),
			new vscode.Position(range.end.line, document.offsetAt(range.end))
		);

		if (useSmartPaste) {
			pasteAsMarkdownLink = checkSmartPaste(document, selectedRange, range);
			markdownLink = pasteAsMarkdownLink; // FIX: this will only match the last range
		}

		const snippet = await tryGetUriListSnippet(document, urlList, token, document.getText(range), placeHolderValue, pasteAsMarkdownLink, isExternalLink);
		if (!snippet) {
			return;
		}

		pasteAsMarkdownLink = true;
		placeHolderValue--;
		edits.push(new vscode.SnippetTextEdit(range, snippet.snippet));
		label = snippet.label;
	}

	const additionalEdits = new vscode.WorkspaceEdit();
	additionalEdits.set(document.uri, edits);

	return { additionalEdits, label, markdownLink };
}

export function checkSmartPaste(document: SkinnyTextDocument, selectedRange: vscode.Range, range: vscode.Range): boolean {
	if (selectedRange.isEmpty || /^[\s\n]*$/.test(document.getText(range)) || validateLink(document.getText(range)).isValid) {
		return false;
	}
	if (/\[.*\]\(.*\)/.test(document.getText(range)) || /!\[.*\]\(.*\)/.test(document.getText(range))) {
		return false;
	}
	for (const regex of smartPasteRegexes) {
		const matches = [...document.getText().matchAll(regex.regex)];
		for (const match of matches) {
			if (match.index !== undefined) {
				const useDefaultPaste = selectedRange.start.character > match.index && selectedRange.end.character < match.index + match[0].length;
				if (useDefaultPaste) {
					return false;
				}
			}
		}
	}
	return true;
}

export function validateLink(urlList: string): { isValid: boolean; cleanedUrlList: string } {
	let isValid = false;
	let uri = undefined;
	const trimmedUrlList = urlList?.trim(); //remove leading and trailing whitespace and new lines
	try {
		uri = vscode.Uri.parse(trimmedUrlList);
	} catch (error) {
		return { isValid: false, cleanedUrlList: urlList };
	}
	const splitUrlList = trimmedUrlList.split(' ').filter(item => item !== ''); //split on spaces and remove empty strings
	if (uri) {
		isValid = splitUrlList.length === 1 && !splitUrlList[0].includes('\n') && externalUriSchemes.includes(vscode.Uri.parse(splitUrlList[0]).scheme) && !!vscode.Uri.parse(splitUrlList[0]).authority;
	}
	return { isValid, cleanedUrlList: splitUrlList[0] };
}

export async function tryGetUriListSnippet(document: SkinnyTextDocument, urlList: String, token: vscode.CancellationToken, title = '', placeHolderValue = 0, pasteAsMarkdownLink = true, isExternalLink = false): Promise<{ snippet: vscode.SnippetString; label: string } | undefined> {
	if (token.isCancellationRequested) {
		return undefined;
	}
	const uriStrings: string[] = [];
	const uris: vscode.Uri[] = [];
	for (const resource of urlList.split(/\r?\n/g)) {
		try {
			uris.push(vscode.Uri.parse(resource));
			uriStrings.push(resource);
		} catch {
			// noop
		}
	}
	return createUriListSnippet(document, uris, uriStrings, title, placeHolderValue, pasteAsMarkdownLink, isExternalLink);
}

interface UriListSnippetOptions {
	readonly placeholderText?: string;

	readonly placeholderStartIndex?: number;

	/**
	 * Should the snippet be for an image link or video?
	 *
	 * If `undefined`, tries to infer this from the uri.
	 */
	readonly insertAsMedia?: boolean;

	readonly separator?: string;
}

export function appendToLinkSnippet(
	snippet: vscode.SnippetString,
	title: string,
	uriString: string,
	placeholderValue: number,
	isExternalLink: boolean,
): vscode.SnippetString {
	snippet.appendText('[');
	snippet.appendPlaceholder(escapeBrackets(title) || 'Title', placeholderValue);
	snippet.appendText(`](${escapeMarkdownLinkPath(uriString, isExternalLink)})`);
	return snippet;
}

export function createUriListSnippet(
	document: SkinnyTextDocument,
	uris: readonly vscode.Uri[],
	uriStrings?: readonly string[],
	title = '',
	placeholderValue = 0,
	pasteAsMarkdownLink = true,
	isExternalLink = false,
	options?: UriListSnippetOptions,
): { snippet: vscode.SnippetString; label: string } | undefined {
	if (!uris.length) {
		return;
	}

	const documentDir = getDocumentDir(document.uri);

	let snippet = new vscode.SnippetString();
	let insertedLinkCount = 0;
	let insertedImageCount = 0;
	let insertedAudioVideoCount = 0;

	uris.forEach((uri, i) => {
		const mdPath = getMdPath(documentDir, uri);

		const ext = URI.Utils.extname(uri).toLowerCase().replace('.', '');
		const insertAsMedia = typeof options?.insertAsMedia === 'undefined' ? mediaFileExtensions.has(ext) : !!options.insertAsMedia;
		const insertAsVideo = mediaFileExtensions.get(ext) === MediaKind.Video;
		const insertAsAudio = mediaFileExtensions.get(ext) === MediaKind.Audio;

		if (insertAsVideo) {
			insertedAudioVideoCount++;
			snippet.appendText(`<video src="${escapeHtmlAttribute(mdPath)}" controls title="`);
			snippet.appendPlaceholder(escapeBrackets(title) || 'Title', placeholderValue);
			snippet.appendText('"></video>');
		} else if (insertAsAudio) {
			insertedAudioVideoCount++;
			snippet.appendText(`<audio src="${escapeHtmlAttribute(mdPath)}" controls title="`);
			snippet.appendPlaceholder(escapeBrackets(title) || 'Title', placeholderValue);
			snippet.appendText('"></audio>');
		} else if (insertAsMedia) {
			if (insertAsMedia) {
				insertedImageCount++;
				if (pasteAsMarkdownLink) {
					snippet.appendText('![');
					const placeholderText = escapeBrackets(title) || options?.placeholderText || 'Alt text';
					const placeholderIndex = typeof options?.placeholderStartIndex !== 'undefined' ? options?.placeholderStartIndex + i : (placeholderValue === 0 ? undefined : placeholderValue);
					snippet.appendPlaceholder(placeholderText, placeholderIndex);
					snippet.appendText(`](${escapeMarkdownLinkPath(mdPath, isExternalLink)})`);
				} else {
					snippet.appendText(escapeMarkdownLinkPath(mdPath, isExternalLink));
				}
			}
		} else {
			insertedLinkCount++;
			if (uriStrings && isExternalLink) {
				snippet = appendToLinkSnippet(snippet, title, uriStrings[i], placeholderValue, isExternalLink);
			} else {
				snippet.appendText(escapeMarkdownLinkPath(mdPath, isExternalLink));
			}
		}

		if (i < uris.length - 1 && uris.length > 1) {
			snippet.appendText(options?.separator ?? ' ');
		}
	});

	let label: string;
	if (insertedAudioVideoCount > 0) {
		if (insertedLinkCount > 0) {
			label = vscode.l10n.t('Insert Markdown Media and Links');
		} else {
			label = vscode.l10n.t('Insert Markdown Media');
		}
	} else if (insertedImageCount > 0 && insertedLinkCount > 0) {
		label = vscode.l10n.t('Insert Markdown Images and Links');
	} else if (insertedImageCount > 0) {
		label = insertedImageCount > 1
			? vscode.l10n.t('Insert Markdown Images')
			: vscode.l10n.t('Insert Markdown Image');
	} else {
		label = insertedLinkCount > 1
			? vscode.l10n.t('Insert Markdown Links')
			: vscode.l10n.t('Insert Markdown Link');
	}

	return { snippet, label };
}

/**
 * Create a new edit from the image files in a data transfer.
 *
 * This tries copying files outside of the workspace into the workspace.
 */
export async function createEditForMediaFiles(
	document: vscode.TextDocument,
	dataTransfer: vscode.DataTransfer,
	token: vscode.CancellationToken
): Promise<{ snippet: vscode.SnippetString; label: string; additionalEdits: vscode.WorkspaceEdit } | undefined> {
	if (document.uri.scheme === Schemes.untitled) {
		return;
	}

	interface FileEntry {
		readonly uri: vscode.Uri;
		readonly newFile?: { readonly contents: vscode.DataTransferFile; readonly overwrite: boolean };
	}

	const pathGenerator = new NewFilePathGenerator();
	const fileEntries = coalesce(await Promise.all(Array.from(dataTransfer, async ([mime, item]): Promise<FileEntry | undefined> => {
		if (!mediaMimes.has(mime)) {
			return;
		}

		const file = item?.asFile();
		if (!file) {
			return;
		}

		if (file.uri) {
			// If the file is already in a workspace, we don't want to create a copy of it
			const workspaceFolder = vscode.workspace.getWorkspaceFolder(file.uri);
			if (workspaceFolder) {
				return { uri: file.uri };
			}
		}

		const newFile = await pathGenerator.getNewFilePath(document, file, token);
		if (!newFile) {
			return;
		}
		return { uri: newFile.uri, newFile: { contents: file, overwrite: newFile.overwrite } };
	})));
	if (!fileEntries.length) {
		return;
	}

	const workspaceEdit = new vscode.WorkspaceEdit();
	for (const entry of fileEntries) {
		if (entry.newFile) {
			workspaceEdit.createFile(entry.uri, {
				contents: entry.newFile.contents,
				overwrite: entry.newFile.overwrite,
			});
		}
	}

	const snippet = createUriListSnippet(document, fileEntries.map(entry => entry.uri));
	if (!snippet) {
		return;
	}

	return {
		snippet: snippet.snippet,
		label: snippet.label,
		additionalEdits: workspaceEdit,
	};
}

function getMdPath(dir: vscode.Uri | undefined, file: vscode.Uri) {
	if (dir && dir.scheme === file.scheme && dir.authority === file.authority) {
		if (file.scheme === Schemes.file) {
			// On windows, we must use the native `path.relative` to generate the relative path
			// so that drive-letters are resolved cast insensitively. However we then want to
			// convert back to a posix path to insert in to the document.
			const relativePath = path.relative(dir.fsPath, file.fsPath);
			return path.posix.normalize(relativePath.split(path.sep).join(path.posix.sep));
		}

		return path.posix.relative(dir.path, file.path);
	}

	return file.toString(false);
}

function escapeHtmlAttribute(attr: string): string {
	return encodeURI(attr).replaceAll('"', '&quot;');
}

function escapeMarkdownLinkPath(mdPath: string, isExternalLink: boolean): string {
	if (needsBracketLink(mdPath)) {
		return '<' + mdPath.replaceAll('<', '\\<').replaceAll('>', '\\>') + '>';
	}

	return isExternalLink ? mdPath : encodeURI(mdPath);
}

function escapeBrackets(value: string): string {
	value = value.replace(/[\[\]]/g, '\\$&'); // CodeQL [SM02383] The Markdown is fully sanitized after being rendered.
	return value;
}

function needsBracketLink(mdPath: string) {
	// Links with whitespace or control characters must be enclosed in brackets
	if (mdPath.startsWith('<') || /\s|[\u007F\u0000-\u001f]/.test(mdPath)) {
		return true;
	}

	// Check if the link has mis-matched parens
	if (!/[\(\)]/.test(mdPath)) {
		return false;
	}

	let previousChar = '';
	let nestingCount = 0;
	for (const char of mdPath) {
		if (char === '(' && previousChar !== '\\') {
			nestingCount++;
		} else if (char === ')' && previousChar !== '\\') {
			nestingCount--;
		}

		if (nestingCount < 0) {
			return true;
		}
		previousChar = char;
	}

	return nestingCount > 0;
}