import { randomUUID } from "node:crypto";
import { existsSync, readFileSync } from "node:fs";
import { writeFile } from "node:fs/promises";
import { join } from "node:path";
import type { FastifyInstance } from "fastify";
import sharp from "sharp";
import { z } from "zod";
import { autoOrient } from "../../lib/auto-orient.js";
import { formatZodErrors } from "../../lib/errors.js";
import { ensureSharpCompat } from "../../lib/heic-converter.js";
import { renderMemeTextSvg } from "../../lib/meme-text-renderer.js";
import { createWorkspace } from "../../lib/workspace.js";
import { registerToolProcessFn } from "../tool-factory.js";

// ---------------------------------------------------------------------------
// Schema
// ---------------------------------------------------------------------------

const settingsSchema = z.object({
  templateId: z.string().optional(),
  textLayout: z
    .enum(["top-bottom", "top-only", "bottom-only", "center", "side-by-side"])
    .default("top-bottom"),
  textBoxes: z.array(z.object({ id: z.string(), text: z.string() })).default([]),
  fontFamily: z
    .enum([
      "anton",
      "arial-black",
      "comic-sans",
      "montserrat",
      "bebas-neue",
      "permanent-marker",
      "roboto",
    ])
    .default("anton"),
  fontSize: z.number().min(8).max(200).optional(),
  textColor: z.string().default("#ffffff"),
  strokeColor: z.string().default("#000000"),
  textAlign: z.enum(["left", "center", "right"]).default("center"),
  allCaps: z.boolean().default(true),
});

type Settings = z.infer<typeof settingsSchema>;

// ---------------------------------------------------------------------------
// Preset text layouts (for custom images)
// ---------------------------------------------------------------------------

const PRESET_LAYOUTS: Record<
  string,
  Array<{ id: string; x: number; y: number; width: number; height: number }>
> = {
  "top-bottom": [
    { id: "top", x: 5, y: 2, width: 90, height: 20 },
    { id: "bottom", x: 5, y: 78, width: 90, height: 20 },
  ],
  "top-only": [{ id: "top", x: 5, y: 2, width: 90, height: 25 }],
  "bottom-only": [{ id: "bottom", x: 5, y: 75, width: 90, height: 23 }],
  center: [{ id: "center", x: 10, y: 35, width: 80, height: 30 }],
  "side-by-side": [
    { id: "left", x: 2, y: 35, width: 46, height: 30 },
    { id: "right", x: 52, y: 35, width: 46, height: 30 },
  ],
};

// ---------------------------------------------------------------------------
// Template manifest
// ---------------------------------------------------------------------------

interface TemplateTextBox {
  id: string;
  x: number;
  y: number;
  width: number;
  height: number;
  defaultText?: string;
}

interface Template {
  id: string;
  filename: string;
  width: number;
  height: number;
  textBoxes: TemplateTextBox[];
}

interface Manifest {
  templates: Template[];
}

const STATIC_DIR = join(import.meta.dirname, "../../../static");
const TEMPLATES_DIR = join(STATIC_DIR, "meme-templates");

let manifestCache: Manifest | null = null;

function getManifest(): Manifest {
  if (manifestCache === null) {
    const raw = readFileSync(join(TEMPLATES_DIR, "meme-templates.json"), "utf-8");
    manifestCache = JSON.parse(raw) as Manifest;
  }
  return manifestCache;
}

function findTemplate(templateId: string): Template | undefined {
  return getManifest().templates.find((t) => t.id === templateId);
}

// ---------------------------------------------------------------------------
// Core processing function (shared by HTTP route and pipeline registry)
// ---------------------------------------------------------------------------

async function processMeme(
  imageBuffer: Buffer,
  settings: Settings,
  filename: string,
  templateTextBoxes?: TemplateTextBox[],
): Promise<{ buffer: Buffer; filename: string; contentType: string }> {
  const meta = await sharp(imageBuffer).metadata();
  const imageWidth = meta.width ?? 800;
  const imageHeight = meta.height ?? 600;

  // Resolve text box positions: template boxes or preset layout
  const layoutBoxes =
    templateTextBoxes ?? PRESET_LAYOUTS[settings.textLayout] ?? PRESET_LAYOUTS["top-bottom"];

  // Map settings.textBoxes onto layout positions
  const textBoxes = layoutBoxes
    .map((box) => {
      const userBox = settings.textBoxes.find((tb) => tb.id === box.id);
      return {
        text: userBox?.text ?? "",
        x: box.x,
        y: box.y,
        width: box.width,
        height: box.height,
      };
    })
    .filter((box) => box.text.length > 0);

  let result: Buffer;

  if (textBoxes.length > 0) {
    const svgBuffer = renderMemeTextSvg({
      imageWidth,
      imageHeight,
      textBoxes,
      fontFamily: settings.fontFamily,
      fontSize: settings.fontSize,
      textColor: settings.textColor,
      strokeColor: settings.strokeColor,
      textAlign: settings.textAlign,
      allCaps: settings.allCaps,
    });

    result = await sharp(imageBuffer)
      .composite([{ input: svgBuffer }])
      .toBuffer();
  } else {
    // No text -- just pass the image through
    result = await sharp(imageBuffer).toBuffer();
  }

  return {
    buffer: result,
    filename,
    contentType: "image/png",
  };
}

// ---------------------------------------------------------------------------
// Route registration
// ---------------------------------------------------------------------------

export function registerMemeGenerator(app: FastifyInstance) {
  // Register process function for pipeline/batch compatibility
  registerToolProcessFn({
    toolId: "meme-generator",
    settingsSchema: settingsSchema as z.ZodType<unknown, z.ZodTypeDef, unknown>,
    process: async (inputBuffer: Buffer, settings: unknown, filename: string) => {
      const parsed = settingsSchema.parse(settings);
      const buf = await autoOrient(await ensureSharpCompat(inputBuffer));
      return processMeme(buf, parsed, filename);
    },
  });

  app.post("/api/v1/tools/meme-generator", async (request, reply) => {
    const contentTypeHeader = request.headers["content-type"] ?? "";
    const isMultipart = contentTypeHeader.includes("multipart/form-data");

    let imageBuffer: Buffer | null = null;
    let settingsRaw: unknown = null;
    let filename = "meme.png";

    // ── Parse request ───────────────────────────────────────────────
    if (isMultipart) {
      // Custom image mode: multipart with file + settings
      try {
        const parts = request.parts();
        for await (const part of parts) {
          if (part.type === "file" && part.fieldname === "file") {
            const chunks: Buffer[] = [];
            for await (const chunk of part.file) {
              chunks.push(chunk);
            }
            imageBuffer = Buffer.concat(chunks);
            if (part.filename) {
              filename = part.filename;
            }
          } else if (part.type === "field" && part.fieldname === "settings") {
            try {
              settingsRaw = JSON.parse(part.value as string);
            } catch {
              return reply.status(400).send({ error: "Settings must be valid JSON" });
            }
          }
        }
      } catch (err) {
        return reply.status(400).send({
          error: "Failed to parse multipart request",
          details: err instanceof Error ? err.message : String(err),
        });
      }
    } else {
      // Template mode: JSON body
      settingsRaw = request.body;
    }

    // ── Validate settings ───────────────────────────────────────────
    const result = settingsSchema.safeParse(settingsRaw ?? {});
    if (!result.success) {
      return reply.status(400).send({
        error: "Invalid settings",
        details: formatZodErrors(result.error.issues),
      });
    }
    const settings = result.data;

    // ── Resolve image source ────────────────────────────────────────
    let templateTextBoxes: TemplateTextBox[] | undefined;

    if (settings.templateId) {
      // Template mode
      const template = findTemplate(settings.templateId);
      if (!template) {
        return reply.status(400).send({ error: `Template not found: ${settings.templateId}` });
      }

      const templatePath = join(TEMPLATES_DIR, "full", template.filename);
      if (!existsSync(templatePath)) {
        return reply.status(400).send({ error: `Template image not found: ${template.filename}` });
      }

      imageBuffer = readFileSync(templatePath);
      templateTextBoxes = template.textBoxes;
      filename = `meme-${template.id}.png`;
    } else if (!imageBuffer || imageBuffer.length === 0) {
      return reply.status(400).send({ error: "Either templateId or an image file is required" });
    }

    // ── Process ─────────────────────────────────────────────────────
    try {
      // Normalize the image for Sharp compatibility
      imageBuffer = await autoOrient(await ensureSharpCompat(imageBuffer!));

      const output = await processMeme(imageBuffer, settings, filename, templateTextBoxes);

      const jobId = randomUUID();
      const workspacePath = await createWorkspace(jobId);
      const outputPath = join(workspacePath, "output", output.filename);
      await writeFile(outputPath, output.buffer);

      return reply.send({
        jobId,
        downloadUrl: `/api/v1/download/${jobId}/${encodeURIComponent(output.filename)}`,
        originalSize: imageBuffer.length,
        processedSize: output.buffer.length,
      });
    } catch (err) {
      return reply.status(422).send({
        error: "Processing failed",
        details: err instanceof Error ? err.message : "Meme generation failed",
      });
    }
  });
}