SnapOtter/apps/api/src/routes/tools/strip-metadata.ts

import { parseExif, parseGps, parseXmp, stripMetadata } from "@snapotter/image-engine";
import type { FastifyInstance, FastifyReply, FastifyRequest } from "fastify";
import sharp from "sharp";
import { z } from "zod";
import { sanitizeFilename } from "../../lib/filename.js";
import { createToolRoute } from "../tool-factory.js";

const settingsSchema = z.object({
  stripExif: z.boolean().default(false),
  stripGps: z.boolean().default(false),
  stripIcc: z.boolean().default(false),
  stripXmp: z.boolean().default(false),
  stripAll: z.boolean().default(true),
});

/**
 * Parse ICC profile buffer into basic info.
 */
function parseIccProfile(iccBuffer: Buffer): Record<string, string> {
  const info: Record<string, string> = {};

  if (iccBuffer.length < 128) return info;

  info["Profile Size"] = `${iccBuffer.length} bytes`;

  const colorSpace = iccBuffer.subarray(16, 20).toString("ascii").trim();
  if (colorSpace) info["Color Space"] = colorSpace;

  const pcs = iccBuffer.subarray(20, 24).toString("ascii").trim();
  if (pcs) info["Connection Space"] = pcs;

  const classMap: Record<string, string> = {
    scnr: "Input (Scanner)",
    mntr: "Display (Monitor)",
    prtr: "Output (Printer)",
    link: "Device Link",
    spac: "Color Space",
    abst: "Abstract",
    nmcl: "Named Color",
  };
  const deviceClass = iccBuffer.subarray(12, 16).toString("ascii").trim();
  if (deviceClass) info["Device Class"] = classMap[deviceClass] ?? deviceClass;

  const major = iccBuffer[8];
  const minor = (iccBuffer[9] >> 4) & 0xf;
  if (major) info.Version = `${major}.${minor}`;

  // Extract description tag from ICC tag table
  const tagCount = iccBuffer.readUInt32BE(128);
  for (let i = 0; i < tagCount && i < 50; i++) {
    const tagOffset = 132 + i * 12;
    if (tagOffset + 12 > iccBuffer.length) break;
    const sig = iccBuffer.subarray(tagOffset, tagOffset + 4).toString("ascii");
    if (sig === "desc") {
      const dataOffset = iccBuffer.readUInt32BE(tagOffset + 4);
      const dataLen = iccBuffer.readUInt32BE(tagOffset + 8);
      if (dataOffset + dataLen <= iccBuffer.length && dataLen > 12) {
        const descType = iccBuffer.subarray(dataOffset, dataOffset + 4).toString("ascii");
        if (descType === "desc") {
          const strLen = iccBuffer.readUInt32BE(dataOffset + 8);
          if (strLen > 0 && strLen < 256) {
            const desc = iccBuffer
              .subarray(dataOffset + 12, dataOffset + 12 + strLen - 1)
              .toString("ascii");
            info.Description = desc;
          }
        } else if (descType === "mluc") {
          const recCount = iccBuffer.readUInt32BE(dataOffset + 8);
          if (recCount > 0) {
            const strOffset = iccBuffer.readUInt32BE(dataOffset + 20);
            const strLength = iccBuffer.readUInt32BE(dataOffset + 16);
            if (strOffset && strLength && dataOffset + strOffset + strLength <= iccBuffer.length) {
              const raw = iccBuffer.subarray(
                dataOffset + strOffset,
                dataOffset + strOffset + strLength,
              );
              // ICC mluc strings are UTF-16BE: swap bytes for Node's utf16le decoder
              const swapped = Buffer.alloc(raw.length);
              for (let j = 0; j < raw.length - 1; j += 2) {
                swapped[j] = raw[j + 1];
                swapped[j + 1] = raw[j];
              }
              const desc = swapped.toString("utf16le");
              info.Description = desc.replace(/\0/g, "");
            }
          }
        }
      }
      break;
    }
  }

  return info;
}

export function registerStripMetadata(app: FastifyInstance) {
  // Inspect endpoint — returns parsed metadata as JSON
  app.post(
    "/api/v1/tools/strip-metadata/inspect",
    async (request: FastifyRequest, reply: FastifyReply) => {
      let fileBuffer: Buffer | null = null;
      let filename = "image";

      try {
        const parts = request.parts();
        for await (const part of parts) {
          if (part.type === "file") {
            const chunks: Buffer[] = [];
            for await (const chunk of part.file) {
              chunks.push(chunk);
            }
            fileBuffer = Buffer.concat(chunks);
            filename = sanitizeFilename(part.filename ?? "image");
          }
        }
      } catch (err) {
        return reply.status(400).send({
          error: "Failed to parse multipart request",
          details: err instanceof Error ? err.message : String(err),
        });
      }

      if (!fileBuffer || fileBuffer.length === 0) {
        return reply.status(400).send({ error: "No image file provided" });
      }

      try {
        const metadata = await sharp(fileBuffer).metadata();

        const result: Record<string, unknown> = {
          filename,
          fileSize: fileBuffer.length,
        };

        // Parse EXIF
        if (metadata.exif) {
          try {
            const parsed = parseExif(metadata.exif);
            const exifData: Record<string, unknown> = {
              ...parsed.image,
              ...parsed.photo,
              ...parsed.iop,
            };
            const gpsData: Record<string, unknown> = { ...parsed.gps };

            if (Object.keys(parsed.gps).length > 0) {
              const coords = parseGps(parsed.gps);
              if (coords.latitude !== null) gpsData._latitude = coords.latitude;
              if (coords.longitude !== null) gpsData._longitude = coords.longitude;
              if (coords.altitude !== null) gpsData._altitude = coords.altitude;
            }

            if (Object.keys(exifData).length > 0) result.exif = exifData;
            if (Object.keys(gpsData).length > 0) result.gps = gpsData;
          } catch {
            result.exif = null;
            result.exifError = "Failed to parse EXIF data";
          }
        }

        // Parse ICC
        if (metadata.icc) {
          try {
            result.icc = parseIccProfile(metadata.icc);
          } catch {
            result.icc = null;
          }
        }

        // Parse XMP
        if (metadata.xmp) {
          try {
            result.xmp = parseXmp(metadata.xmp);
          } catch {
            result.xmp = null;
          }
        }

        return reply.send(result);
      } catch (err) {
        return reply.status(422).send({
          error: "Failed to read image metadata",
          details: err instanceof Error ? err.message : "Unknown error",
        });
      }
    },
  );

  // Strip endpoint — processes and returns cleaned image
  createToolRoute(app, {
    toolId: "strip-metadata",
    settingsSchema,
    process: async (inputBuffer, settings, filename) => {
      const metadata = await sharp(inputBuffer).metadata();
      const format = metadata.format ?? "png";
      const image = sharp(inputBuffer);
      const result = await stripMetadata(image, settings);

      // Re-encode in the original format so we don't inflate the file.
      // Sharp re-encodes from scratch, so we pick settings that stay close
      // to the original size while still stripping metadata.
      switch (format) {
        case "jpeg":
          result.jpeg({ quality: 90, mozjpeg: true });
          break;
        case "png":
          result.png({ compressionLevel: 9 });
          break;
        case "webp":
          result.webp({ quality: 85 });
          break;
        case "avif":
          result.avif({ quality: 50 });
          break;
        case "tiff":
          result.tiff({ compression: "lzw" });
          break;
        default:
          break;
      }

      const buffer = await result.toBuffer();
      const mimeMap: Record<string, string> = {
        jpeg: "image/jpeg",
        png: "image/png",
        webp: "image/webp",
        avif: "image/avif",
        tiff: "image/tiff",
        gif: "image/gif",
      };
      return { buffer, filename, contentType: mimeMap[format] ?? "image/png" };
    },
  });
}