SnapOtter/apps/api/src/routes/tools/content-aware-resize.ts

import { randomUUID } from "node:crypto";
import { writeFile } from "node:fs/promises";
import { basename, join } from "node:path";
import { seamCarve } from "@stirling-image/ai";
import type { FastifyInstance, FastifyReply, FastifyRequest } from "fastify";
import { z } from "zod";
import { autoOrient } from "../../lib/auto-orient.js";
import { validateImageBuffer } from "../../lib/file-validation.js";
import { createWorkspace } from "../../lib/workspace.js";
import { registerToolProcessFn } from "../tool-factory.js";

const settingsSchema = z.object({
  width: z.number().positive().optional(),
  height: z.number().positive().optional(),
  protectFaces: z.boolean().default(false),
  blurRadius: z.number().min(0).max(20).default(4),
  sobelThreshold: z.number().min(1).max(20).default(2),
  square: z.boolean().default(false),
});

type Settings = z.infer<typeof settingsSchema>;

/** Content-aware resize (seam carving via caire) route. */
export function registerContentAwareResize(app: FastifyInstance) {
  app.post(
    "/api/v1/tools/content-aware-resize",
    async (request: FastifyRequest, reply: FastifyReply) => {
      let fileBuffer: Buffer | null = null;
      let filename = "image";
      let settingsRaw: string | null = null;

      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 = basename(part.filename ?? "image");
          } else if (part.fieldname === "settings") {
            settingsRaw = part.value as string;
          }
        }
      } 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" });
      }

      const validation = await validateImageBuffer(fileBuffer);
      if (!validation.valid) {
        return reply.status(400).send({ error: `Invalid image: ${validation.reason}` });
      }

      // Validate settings
      let settings: Settings;
      try {
        const parsed = settingsRaw ? JSON.parse(settingsRaw) : {};
        const result = settingsSchema.safeParse(parsed);
        if (!result.success) {
          return reply.status(400).send({
            error: "Invalid settings",
            details: result.error.issues.map((i) => ({
              path: i.path.join("."),
              message: i.message,
            })),
          });
        }
        settings = result.data;
      } catch {
        return reply.status(400).send({ error: "Settings must be valid JSON" });
      }

      if (!settings.square && !settings.width && !settings.height) {
        return reply.status(400).send({
          error: "Either width, height, or square mode must be specified",
        });
      }

      try {
        request.log.info(
          {
            toolId: "content-aware-resize",
            imageSize: fileBuffer.length,
            ...settings,
          },
          "Starting content-aware resize",
        );

        // Auto-orient to fix EXIF rotation before seam carving
        fileBuffer = await autoOrient(fileBuffer);

        const jobId = randomUUID();
        const workspacePath = await createWorkspace(jobId);

        // Save input
        const inputPath = join(workspacePath, "input", filename);
        await writeFile(inputPath, fileBuffer);

        // Process with caire
        const result = await seamCarve(fileBuffer, join(workspacePath, "output"), {
          width: settings.width,
          height: settings.height,
          protectFaces: settings.protectFaces,
          blurRadius: settings.blurRadius,
          sobelThreshold: settings.sobelThreshold,
          square: settings.square,
        });

        // Save output
        const outputFilename = `${filename.replace(/\.[^.]+$/, "")}_seam.png`;
        const outputPath = join(workspacePath, "output", outputFilename);
        await writeFile(outputPath, result.buffer);

        return reply.send({
          jobId,
          downloadUrl: `/api/v1/download/${jobId}/${encodeURIComponent(outputFilename)}`,
          originalSize: fileBuffer.length,
          processedSize: result.buffer.length,
          width: result.width,
          height: result.height,
        });
      } catch (err) {
        request.log.error({ err, toolId: "content-aware-resize" }, "Content-aware resize failed");
        return reply.status(422).send({
          error: "Content-aware resize failed",
          details: err instanceof Error ? err.message : "Unknown error",
        });
      }
    },
  );

  // Register in the pipeline/batch registry
  registerToolProcessFn({
    toolId: "content-aware-resize",
    settingsSchema,
    process: async (inputBuffer, settings, filename) => {
      const s = settings as Settings;
      const orientedBuffer = await autoOrient(inputBuffer);
      const jobId = randomUUID();
      const workspacePath = await createWorkspace(jobId);
      const result = await seamCarve(orientedBuffer, join(workspacePath, "output"), {
        width: s.width,
        height: s.height,
        protectFaces: s.protectFaces,
        blurRadius: s.blurRadius,
        sobelThreshold: s.sobelThreshold,
        square: s.square,
      });
      const outputFilename = `${filename.replace(/\.[^.]+$/, "")}_seam.png`;
      return { buffer: result.buffer, filename: outputFilename, contentType: "image/png" };
    },
  });
}