/*
 * Motion graphics renderer for Media Studio (intros, outros, lower thirds,
 * caption previews, end cards).
 *
 * Technology decision: no Remotion and no headless Chromium. Remotion needs a
 * paid company license above a team size and Chromium is a heavy, hard-to-
 * sandbox runtime. Instead every template is a pure TypeScript function that
 * returns an SVG document for a point in time. Frames are rasterized with
 * @resvg/resvg-js (MPL-2.0; resvg itself is MPL-2.0, used unmodified as a
 * library, commercially usable) and piped as PNGs into ffmpeg (LGPL/GPL
 * depending on the build, invoked as a separate process with an argv array),
 * which encodes a QuickTime Animation (qtrle, argb) MOV with alpha. Nothing
 * here needs a network or a hosted service.
 */
import type { ChildProcess } from "node:child_process";
import { spawn } from "node:child_process";
import { randomUUID } from "node:crypto";
import { once } from "node:events";
import { readFile, rename, rm, stat } from "node:fs/promises";
import path from "node:path";
import type { MotionGraphicsRenderer, MotionRenderRequest } from "@rakazo/adapter-kit";
import type { BrandKit, MotionTemplateInfo, MotionTemplateRef } from "@rakazo/contracts";
import { BrandKitSchema, MotionTemplateRefSchema } from "@rakazo/contracts";
import { assertInside } from "@rakazo/media/node";
import type { RenderedImage, ResvgRenderOptions } from "@resvg/resvg-js";
import { renderAsync } from "@resvg/resvg-js";
import type { MotionFrameContext, MotionTemplate } from "./template.js";
import { brandFonts, MotionTemplateError, validateDuration, validateParams } from "./template.js";
import { captionBoldSocial, captionClean, captionKaraoke } from "./templates/captions.js";
import { endCardCta, endCardMinimal } from "./templates/end-cards.js";
import {
  introElegantFade,
  introGlitch,
  introKineticType,
  introLogoReveal,
} from "./templates/intros.js";
import { lowerThirdBar, lowerThirdClean, lowerThirdPill } from "./templates/lower-thirds.js";
import { outroLogo, outroSubscribe } from "./templates/outros.js";

export type { MotionFrameContext, MotionTemplate } from "./template.js";
export { MotionTemplateError } from "./template.js";

export const MOTION_TEMPLATES: readonly MotionTemplate[] = [
  introLogoReveal,
  introKineticType,
  introGlitch,
  introElegantFade,
  outroLogo,
  outroSubscribe,
  lowerThirdClean,
  lowerThirdBar,
  lowerThirdPill,
  captionClean,
  captionKaraoke,
  captionBoldSocial,
  endCardCta,
  endCardMinimal,
];

export function motionTemplate(id: string): MotionTemplate {
  const template = MOTION_TEMPLATES.find((entry) => entry.info.id === id);
  if (!template) throw new MotionTemplateError("unknown_template", `unknown template "${id}"`);
  return template;
}

export const MIN_FRAME_SIDE = 16;
export const MAX_FRAME_SIDE = 3840;
export const MAX_FPS = 60;
/** Default cap on width × height × frames: ten seconds of 1080p60. */
export const DEFAULT_MAX_PIXEL_FRAMES = 1920 * 1080 * 60 * 10;
const MAX_LOGO_BYTES = 5 * 1024 * 1024;
const PNG_SIGNATURE = Buffer.from([0x89, 0x50, 0x4e, 0x47, 0x0d, 0x0a, 0x1a, 0x0a]);
const FONT_EXTENSIONS = new Set([".ttf", ".otf", ".ttc"]);

/**
 * Read a logo as a data URI. Only PNG and SVG are accepted, and an SVG may not
 * declare entities or reference anything outside itself.
 */
export async function loadLogoDataUri(file: string): Promise<string> {
  const extension = path.extname(file).toLowerCase();
  if (extension !== ".png" && extension !== ".svg")
    throw new MotionTemplateError("invalid_asset", "logos must be PNG or SVG");
  const info = await stat(file);
  if (!info.isFile() || info.size > MAX_LOGO_BYTES)
    throw new MotionTemplateError("invalid_asset", "logo is not a file or is too large");
  const bytes = await readFile(file);
  if (extension === ".png") {
    if (!bytes.subarray(0, 8).equals(PNG_SIGNATURE))
      throw new MotionTemplateError("invalid_asset", "logo is not a PNG");
    return `data:image/png;base64,${bytes.toString("base64")}`;
  }
  const text = bytes.toString("utf8");
  if (!/<svg[\s>]/i.test(text))
    throw new MotionTemplateError("invalid_asset", "logo is not an SVG");
  if (/<!DOCTYPE|<!ENTITY/i.test(text) || /\bhref\s*=\s*["']\s*(?!#|data:)/i.test(text))
    throw new MotionTemplateError("invalid_asset", "SVG logos must be self-contained");
  return `data:image/svg+xml;base64,${bytes.toString("base64")}`;
}

/** Validate a template reference and assemble the pure frame context. */
export function buildFrameContext(input: {
  template: MotionTemplateRef;
  kit: BrandKit;
  width: number;
  height: number;
  logos: string[];
}): { template: MotionTemplate; ctx: MotionFrameContext } {
  const ref = MotionTemplateRefSchema.parse(input.template);
  const kit = BrandKitSchema.parse(input.kit);
  const template = motionTemplate(ref.templateId);
  validateDuration(template.info, ref.durationMs);
  for (const side of [input.width, input.height]) {
    if (!Number.isInteger(side) || side < MIN_FRAME_SIDE || side > MAX_FRAME_SIDE)
      throw new MotionTemplateError(
        "invalid_size",
        `frame sides must be ${MIN_FRAME_SIDE}..${MAX_FRAME_SIDE} px`,
      );
  }
  return {
    template,
    ctx: {
      width: input.width,
      height: input.height,
      durationMs: ref.durationMs,
      kit,
      params: validateParams(template.info, ref.params),
      logos: input.logos,
      fonts: brandFonts(kit),
    },
  };
}

export interface RasterizeOptions {
  fontFiles: string[];
  defaultFontFamily?: string | null;
  /** Fall back to system fonts for missing families and glyphs. */
  loadSystemFonts: boolean;
}

export function rasterizeFrame(svg: string, options: RasterizeOptions): Promise<RenderedImage> {
  const resvgOptions: ResvgRenderOptions = {
    font: {
      loadSystemFonts: options.loadSystemFonts,
      fontFiles: options.fontFiles,
      ...(options.defaultFontFamily ? { defaultFontFamily: options.defaultFontFamily } : {}),
    },
    logLevel: "off",
  };
  return renderAsync(svg, resvgOptions);
}

export function frameCount(durationMs: number, fps: number): number {
  return Math.max(1, Math.round((durationMs * fps) / 1000));
}

function abortError(): Error {
  const error = new Error("motion render aborted");
  error.name = "AbortError";
  return error;
}

export interface ResvgMotionGraphicsRendererOptions {
  ffmpegPath?: string;
  /** When set, every asset path and the output path must lie inside it. */
  root?: string;
  maxPixelFrames?: number;
}

export class ResvgMotionGraphicsRenderer implements MotionGraphicsRenderer {
  readonly id = "resvg";
  private readonly ffmpegPath: string;
  private readonly maxPixelFrames: number;

  constructor(private readonly options: ResvgMotionGraphicsRendererOptions = {}) {
    this.ffmpegPath = options.ffmpegPath ?? "ffmpeg";
    this.maxPixelFrames = options.maxPixelFrames ?? DEFAULT_MAX_PIXEL_FRAMES;
  }

  templates(): MotionTemplateInfo[] {
    return MOTION_TEMPLATES.map((template) => structuredClone(template.info));
  }

  async render(request: MotionRenderRequest): Promise<{ path: string; hasAlpha: boolean }> {
    const { signal } = request;
    if (signal?.aborted) throw abortError();
    if (!Number.isFinite(request.fps) || request.fps < 1 || request.fps > MAX_FPS)
      throw new MotionTemplateError("invalid_size", `fps must be 1..${MAX_FPS}`);
    if (!path.isAbsolute(request.outPath) || path.extname(request.outPath).toLowerCase() !== ".mov")
      throw new MotionTemplateError("invalid_asset", "outPath must be an absolute .mov path");

    const outPath = await this.checkedPath(request.outPath);
    const fontFiles: string[] = [];
    for (const font of request.assets.fonts) {
      const file = await this.checkedPath(font.path);
      if (!FONT_EXTENSIONS.has(path.extname(file).toLowerCase()) || !(await stat(file)).isFile())
        throw new MotionTemplateError("invalid_asset", "fonts must be TTF, OTF, or TTC files");
      fontFiles.push(file);
    }
    const logos: string[] = [];
    for (const logo of request.assets.logoPaths) {
      logos.push(await loadLogoDataUri(await this.checkedPath(logo)));
    }

    const { template, ctx } = buildFrameContext({
      template: request.template,
      kit: request.brandKit,
      width: request.width,
      height: request.height,
      logos,
    });
    const frames = frameCount(ctx.durationMs, request.fps);
    if (ctx.width * ctx.height * frames > this.maxPixelFrames)
      throw new MotionTemplateError("invalid_size", "motion clip exceeds the pixel budget");

    const raster: RasterizeOptions = {
      fontFiles,
      defaultFontFamily: ctx.fonts.body,
      loadSystemFonts: true,
    };
    const partial = path.join(
      path.dirname(outPath),
      `.${path.basename(outPath, ".mov")}.${randomUUID()}.partial.mov`,
    );
    const child = spawn(
      this.ffmpegPath,
      [
        "-hide_banner",
        "-loglevel",
        "error",
        "-nostdin",
        "-f",
        "image2pipe",
        "-framerate",
        String(request.fps),
        "-c:v",
        "png",
        "-i",
        "pipe:0",
        "-an",
        "-c:v",
        "qtrle",
        "-pix_fmt",
        "argb",
        "-f",
        "mov",
        partial,
      ],
      { stdio: ["pipe", "ignore", "pipe"], shell: false },
    );
    const exited = waitForExit(child);
    const kill = () => child.kill("SIGKILL");
    signal?.addEventListener("abort", kill, { once: true });
    try {
      const stdin = child.stdin!;
      stdin.on("error", () => {});
      for (let index = 0; index < frames; index += 1) {
        if (signal?.aborted) throw abortError();
        const svg = template.frame((index * 1000) / request.fps, ctx);
        const png = (await rasterizeFrame(svg, raster)).asPng();
        if (signal?.aborted) throw abortError();
        if (!stdin.write(png)) {
          const result = await Promise.race([once(stdin, "drain").then(() => null), exited]);
          if (result) throw ffmpegError(result);
        }
      }
      stdin.end();
      const result = await exited;
      if (signal?.aborted) throw abortError();
      if (result.code !== 0) throw ffmpegError(result);
      await rename(partial, outPath);
      return { path: outPath, hasAlpha: true };
    } catch (error) {
      kill();
      await exited;
      await rm(partial, { force: true });
      throw signal?.aborted ? abortError() : error;
    } finally {
      signal?.removeEventListener("abort", kill);
    }
  }

  private async checkedPath(file: string): Promise<string> {
    if (!path.isAbsolute(file) || file.includes("\0"))
      throw new MotionTemplateError("invalid_asset", "asset paths must be absolute");
    return this.options.root ? assertInside(this.options.root, file) : path.resolve(file);
  }
}

interface ExitResult {
  code: number | null;
  stderr: string;
}

function waitForExit(child: ChildProcess): Promise<ExitResult> {
  let stderr = "";
  child.stderr?.setEncoding("utf8");
  child.stderr?.on("data", (chunk: string) => {
    stderr = (stderr + chunk).slice(-4000);
  });
  return new Promise((resolve) => {
    child.once("error", (error) => resolve({ code: -1, stderr: error.message }));
    child.once("close", (code) => resolve({ code, stderr }));
  });
}

function ffmpegError(result: ExitResult): Error {
  return new Error(`ffmpeg failed (${result.code}): ${result.stderr.trim()}`);
}