/*
 * SPDX-FileCopyrightText: syuilo and misskey-project
 * SPDX-License-Identifier: AGPL-3.0-only
 */

import fs from 'node:fs/promises';
import { Inject, Injectable } from '@nestjs/common';
import FFmpeg from 'fluent-ffmpeg';
import { DI } from '@/di-symbols.js';
import type { Config } from '@/config.js';
import { ImageProcessingService } from '@/core/ImageProcessingService.js';
import type { IImage } from '@/core/ImageProcessingService.js';
import { createTemp, createTempDir } from '@/misc/create-temp.js';
import { bindThis } from '@/decorators.js';
import { appendQuery, query } from '@/misc/prelude/url.js';
import { LoggerService } from '@/core/LoggerService.js';
import type Logger from '@/logger.js';

// faststart is only supported for MP4, M4A, M4W and MOV files (the MOV family).
// WebM (and Matroska) files always support faststart-like behavior.
const supportedMimeTypes = new Map([
	['video/mp4', 'mp4'],
	['video/m4a', 'mp4'],
	['video/m4v', 'mp4'],
	['video/quicktime', 'mov'],
]);

@Injectable()
export class VideoProcessingService {
	private readonly logger: Logger;

	constructor(
		@Inject(DI.config)
		private config: Config,

		private imageProcessingService: ImageProcessingService,

		private loggerService: LoggerService,
	) {
		this.logger = this.loggerService.getLogger('video-processing');
	}

	@bindThis
	public async generateVideoThumbnail(source: string): Promise<IImage> {
		const [dir, cleanup] = await createTempDir();

		try {
			await new Promise((res, rej) => {
				FFmpeg({
					source,
				})
					.on('end', res)
					.on('error', rej)
					.screenshot({
						folder: dir,
						filename: 'out.png',	// must have .png extension
						count: 1,
						timestamps: ['5%'],
					});
			});

			return await this.imageProcessingService.convertToWebp(`${dir}/out.png`, 498, 422);
		} finally {
			cleanup();
		}
	}

	@bindThis
	public getExternalVideoThumbnailUrl(url: string): string | null {
		if (this.config.videoThumbnailGenerator == null) return null;

		return appendQuery(
			`${this.config.videoThumbnailGenerator}/thumbnail.webp`,
			query({
				thumbnail: '1',
				url,
			}),
		);
	}

	/**
	 * Optimize video for web playback by adding faststart flag.
	 * This allows the video to start playing before it is fully downloaded.
	 * The original file is modified in-place.
	 * @param source Path to the video file
	 * @param mimeType The MIME type of the video
	 * @returns Promise that resolves when optimization is complete
	 */
	@bindThis
	public async webOptimizeVideo(source: string, mimeType: string): Promise<void> {
		const outputFormat = supportedMimeTypes.get(mimeType);
		if (!outputFormat) {
			this.logger.debug(`Skipping web optimization for unsupported MIME type: ${mimeType}`);
			return;
		}

		const [tempPath, cleanup] = await createTemp();

		try {
			await new Promise<void>((resolve, reject) => {
				FFmpeg(source)
					.format(outputFormat) // Specify output format
					.addOutputOptions('-c copy') // Copy streams without re-encoding
					.addOutputOptions('-movflags +faststart')
					.on('error', reject)
					.on('end', async () => {
						try {
							// Replace original file with optimized version
							await fs.copyFile(tempPath, source);
							this.logger.info(`Web-optimized video: ${source}`);
							resolve();
						} catch (copyError) {
							reject(copyError);
						}
					})
					.save(tempPath);
			});
		} catch (error) {
			this.logger.warn(`Failed to web-optimize video: ${source}`, { error });
			throw error;
		} finally {
			cleanup();
		}
	}
}