import { useEffect, useState } from "react";
import {
  AbsoluteFill,
  Audio,
  Sequence,
  staticFile,
  CalculateMetadataFunction,
} from "remotion";
import { LAYOUT_REGISTRY, LayoutType, SceneLayoutProps } from "./components/layouts";
import { TransitionWipe } from "./components/Transitions";
import { LogoOverlay } from "./components/LogoOverlay";

// ─── Types ───────────────────────────────────────────────────

interface SceneData {
  id: number;
  order: number;
  title: string;
  narration: string;
  layout: LayoutType;
  layoutProps: Record<string, any>;
  durationSeconds: number;
  voiceoverFile: string | null;
  images: string[];
}

interface VideoData {
  projectName: string;
  heroImage?: string | null;
  accentColor: string;
  bgColor: string;
  textColor: string;
  logo?: string | null;
  logoPosition?: string;
  logoOpacity?: number;
  aspectRatio?: string;
  scenes: SceneData[];
}

interface VideoProps {
  dataUrl: string;
}

// ─── Calculate actual duration from data.json ────────────────

export const calculateVideoMetadata: CalculateMetadataFunction<VideoProps> =
  async ({ props }) => {
    const FPS = 30;
    try {
      const url = staticFile(props.dataUrl.replace(/^\//, ""));
      const res = await fetch(url);
      if (!res.ok) throw new Error(`Failed to fetch ${url}`);
      const data: VideoData = await res.json();

      const totalSeconds = data.scenes.reduce(
        (sum, s) => sum + (s.durationSeconds || 5),
        0
      );
      const totalFrames = Math.ceil((totalSeconds + 2) * FPS);

      const isPortrait = data.aspectRatio === "portrait";

      return {
        durationInFrames: Math.max(totalFrames, FPS * 5),
        fps: FPS,
        width: isPortrait ? 1080 : 1920,
        height: isPortrait ? 1920 : 1080,
      };
    } catch (e) {
      console.warn("calculateVideoMetadata fallback:", e);
      return {
        durationInFrames: FPS * 300,
        fps: FPS,
        width: 1920,
        height: 1080,
      };
    }
  };

// ─── Main composition ────────────────────────────────────────

export const ExplainerVideo: React.FC<VideoProps> = ({ dataUrl }) => {
  const [data, setData] = useState<VideoData | null>(null);

  useEffect(() => {
    fetch(staticFile(dataUrl.replace(/^\//, "")))
      .then((res) => res.json())
      .then(setData)
      .catch(() => {
        setData({
          projectName: "Blog2Video Preview",
          accentColor: "#7C3AED",
          bgColor: "#FFFFFF",
          textColor: "#000000",
          scenes: [
            {
              id: 1,
              order: 1,
              title: "Welcome",
              narration: "This is a preview of your Blog2Video project.",
              layout: "text_narration",
              layoutProps: {},
              durationSeconds: 5,
              voiceoverFile: null,
              images: [],
            },
          ],
        });
      });
  }, [dataUrl]);

  if (!data) {
    return (
      <AbsoluteFill
        style={{
          backgroundColor: "#FFFFFF",
          display: "flex",
          alignItems: "center",
          justifyContent: "center",
        }}
      >
        <p style={{ color: "#000000", fontSize: 36 }}>Loading...</p>
      </AbsoluteFill>
    );
  }

  const FPS = 30;
  let currentFrame = 0;

  return (
    <AbsoluteFill style={{ backgroundColor: data.bgColor || "#FFFFFF" }}>
      {data.scenes.map((scene, index) => {
        const durationFrames = Math.round(scene.durationSeconds * FPS);
        const startFrame = currentFrame;
        currentFrame += durationFrames;

        // Pick layout component from registry
        const LayoutComponent =
          LAYOUT_REGISTRY[scene.layout] || LAYOUT_REGISTRY.text_narration;

        // Resolve image URL via staticFile
        const imageUrl =
          scene.images.length > 0 ? staticFile(scene.images[0]) : undefined;

        // Build props for the layout component
        const layoutProps: SceneLayoutProps = {
          title: scene.title,
          narration: scene.narration,
          imageUrl,
          accentColor: data.accentColor || "#7C3AED",
          bgColor: data.bgColor || "#FFFFFF",
          textColor: data.textColor || "#000000",
          aspectRatio: data.aspectRatio || "landscape",
          ...scene.layoutProps,
        };

        return (
          <Sequence
            key={scene.id}
            from={startFrame}
            durationInFrames={durationFrames}
            name={scene.title}
          >
            <LayoutComponent {...layoutProps} />

            {/* Voiceover audio */}
            {scene.voiceoverFile && (
              <Audio src={staticFile(scene.voiceoverFile)} />
            )}

            {/* Transition overlay */}
            {index < data.scenes.length - 1 && (
              <Sequence from={durationFrames - 15} durationInFrames={15}>
                <TransitionWipe />
              </Sequence>
            )}
          </Sequence>
        );
      })}

      {/* Logo overlay — spans entire video */}
      {data.logo && (
        <LogoOverlay
          src={staticFile(data.logo)}
          position={data.logoPosition || "bottom_right"}
          maxOpacity={data.logoOpacity ?? 0.9}
          aspectRatio={data.aspectRatio || "landscape"}
        />
      )}
    </AbsoluteFill>
  );
};