import sharp from "sharp";
import type { FastifyInstance, FastifyRequest, FastifyReply } from "fastify";
import { basename } from "node:path";

/**
 * Image info route - read-only, returns JSON metadata.
 * Does NOT use createToolRoute since it doesn't produce a processed file.
 */
export function registerInfo(app: FastifyInstance) {
  app.post(
    "/api/v1/tools/info",
    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 = basename(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 stats = await sharp(fileBuffer).stats();

        // Build histogram data from stats
        const histogram = stats.channels.map((ch, i) => ({
          channel: ["red", "green", "blue", "alpha"][i] ?? `channel-${i}`,
          min: ch.min,
          max: ch.max,
          mean: Math.round(ch.mean * 100) / 100,
          stdev: Math.round(ch.stdev * 100) / 100,
        }));

        return reply.send({
          filename,
          fileSize: fileBuffer.length,
          width: metadata.width ?? 0,
          height: metadata.height ?? 0,
          format: metadata.format ?? "unknown",
          channels: metadata.channels ?? 0,
          hasAlpha: metadata.hasAlpha ?? false,
          colorSpace: metadata.space ?? "unknown",
          density: metadata.density ?? null,
          isProgressive: metadata.isProgressive ?? false,
          orientation: metadata.orientation ?? null,
          hasProfile: metadata.hasProfile ?? false,
          hasExif: !!metadata.exif,
          hasIcc: !!metadata.icc,
          hasXmp: !!metadata.xmp,
          bitDepth: metadata.depth ?? null,
          pages: metadata.pages ?? 1,
          histogram,
        });
      } catch (err) {
        return reply.status(422).send({
          error: "Failed to read image metadata",
          details: err instanceof Error ? err.message : "Unknown error",
        });
      }
    },
  );
}