import { spawn } from "child_process";
import { StoryConfig } from "./config";
import * as path from "path";
import ffmpeg from "ffmpeg-static";

function escapeForFilter(filePath: string): string {
  return filePath.replace(/\\/g, "\\\\").replace(/:/g, "\\:").replace(/,/g, "\\,").replace(/'/g, "\\'");
}

export async function createVideo(
  storyName: string,
  storyConfig: StoryConfig,
  imageFiles: string[],
  chunkDurations: number[],
  srtPath: string
): Promise<void> {
  const ffmpegPath: string = (ffmpeg as unknown as string) || "ffmpeg";
  const audioPath = path.resolve("stories", storyName, "final_audio", "final.mp3");
  const videoPath = path.resolve("stories", storyName, "video", "final.mp4");
  const totalDuration = chunkDurations.reduce((a, b) => a + b, 0);
  const resolution = storyConfig.config.export_settings?.resolution || "1024x1024";

  const inputs = imageFiles.map((file) => ["-loop", "1", "-i", file]).flat();
  inputs.push("-i", audioPath);

  const filterGraph = imageFiles
    .map((_, i) => {
      const duration = chunkDurations[i];
      const zoompan = `zoompan=z='min(zoom+0.0015,1.5)':d=${25 * duration}:x='iw/2-(iw/zoom/2)':y='ih/2-(ih/zoom/2)':s=${resolution}`;
      return `[${i}:v]${zoompan},fade=t=out:st=${duration - 1}:d=1[v${i}]`;
    })
    .join(";");

  const streamSpecifiers = imageFiles.map((_, i) => `[v${i}]`).join("");
  const escapedSrt = escapeForFilter(srtPath);
  const concatGraph = `${filterGraph};${streamSpecifiers}concat=n=${imageFiles.length}:v=1:a=0,format=yuv420p[v0]`;
  const finalFilterGraph = `${concatGraph};[v0]subtitles='${escapedSrt}'[v]`;

  const args = [
    "-y",
    ...inputs,
    "-filter_complex",
    finalFilterGraph,
    "-map",
    "[v]",
    "-map",
    `${imageFiles.length}:a`,
    "-c:v",
    "libx264",
    "-tune",
    "stillimage",
    "-c:a",
    "aac",
    "-b:a",
    "192k",
    "-pix_fmt",
    "yuv420p",
    "-t",
    totalDuration.toString(),
    videoPath,
  ];

  const ffmpegProcess = spawn(ffmpegPath, args);

  return new Promise<void>((resolve, reject) => {
    ffmpegProcess.on("close", (code: number | null) => {
      if (code === 0) {
        resolve();
      } else {
        reject(new Error(`ffmpeg process exited with code ${code}`));
      }
    });
  });
}