// Library export/import — bulk JSON dump + restore of sessions, folder
// meta, and subscriptions. Only routes; no module state. Pulls history
// data from history.js helpers; reads/writes the subscriptions file
// directly because library import predates the subscriptions module
// having a public 'merge' helper (and the merge logic is library-
// specific anyway).

import fs from "fs/promises";
import path from "path";
import express from "express";
import { getHistoryDir, loadMeta, saveMeta } from "./history.js";

// ── Routes ──────────────────────────────────────────────────────────────────
// Both routes are gated by the Pro 'library' entitlement (the gate runs
// upstream in license-middleware.js). They assume initHistory() has
// already been called.
export function setupLibraryRoutes(app) {
  // Bulk export everything: meta, sessions, subscriptions.
  app.get("/api/library/export", async (req, res) => {
    try {
      const historyDir = getHistoryDir();
      const meta = await loadMeta();
      const files = await fs.readdir(historyDir);
      const sessions = {};
      for (const file of files) {
        if (
          !file.endsWith(".json") ||
          file === "_meta.json" ||
          file === "subscriptions.json" ||
          file === "auto-queue.json" ||
          file === "skip-list.json" ||
          file === "seen-list.json"
        ) continue;
        try {
          const raw = await fs.readFile(path.join(historyDir, file), "utf-8");
          const id = file.replace(".json", "");
          sessions[id] = JSON.parse(raw);
        } catch {}
      }
      let subscriptions = [];
      try {
        subscriptions = JSON.parse(
          await fs.readFile(path.join(historyDir, "subscriptions.json"), "utf-8")
        ).subscriptions || [];
      } catch {}

      const exportData = {
        version: 1,
        exportedAt: new Date().toISOString(),
        meta,
        sessions,
        subscriptions,
      };
      res.setHeader("Content-Type", "application/json");
      res.setHeader(
        "Content-Disposition",
        'attachment; filename="recap-library.json"'
      );
      res.json(exportData);
    } catch (err) {
      res.status(500).json({ error: err.message });
    }
  });

  // Bulk import: skip sessions that already exist (don't overwrite),
  // merge meta folders, add net-new subscriptions.
  app.post(
    "/api/library/import",
    express.json({ limit: "200mb" }),
    async (req, res) => {
      try {
        const data = req.body;
        if (!data || !data.sessions) {
          return res
            .status(400)
            .json({ error: "Invalid library file — missing sessions data" });
        }

        const historyDir = getHistoryDir();
        let imported = 0;
        let skipped = 0;

        // Sessions — skip if already present.
        for (const [id, session] of Object.entries(data.sessions)) {
          const filePath = path.join(historyDir, `${id}.json`);
          try {
            await fs.access(filePath);
            skipped++;
            continue;
          } catch {}
          await fs.writeFile(filePath, JSON.stringify(session));
          imported++;
        }

        // Meta — merge folders + add new uncategorized at the top.
        if (data.meta) {
          const existingMeta = await loadMeta();
          const allExistingIds = new Set([
            ...existingMeta.uncategorized,
            ...existingMeta.folders.flatMap(f => f.items),
          ]);

          if (data.meta.folders) {
            for (const folder of data.meta.folders) {
              const existingFolder = existingMeta.folders.find(
                f => f.id === folder.id
              );
              if (!existingFolder) {
                existingMeta.folders.push(folder);
                folder.items.forEach(id => allExistingIds.add(id));
              }
            }
          }

          if (data.meta.uncategorized) {
            for (const id of data.meta.uncategorized) {
              if (!allExistingIds.has(id)) {
                existingMeta.uncategorized.unshift(id);
              }
            }
          }

          await saveMeta(existingMeta);
        }

        // Subscriptions — merge, dedupe by URL.
        if (data.subscriptions && data.subscriptions.length > 0) {
          let existingSubs = [];
          try {
            existingSubs = JSON.parse(
              await fs.readFile(
                path.join(historyDir, "subscriptions.json"),
                "utf-8"
              )
            ).subscriptions || [];
          } catch {}
          const existingUrls = new Set(existingSubs.map(s => s.url));
          for (const sub of data.subscriptions) {
            if (!existingUrls.has(sub.url)) {
              existingSubs.push(sub);
            }
          }
          await fs.writeFile(
            path.join(historyDir, "subscriptions.json"),
            JSON.stringify({ subscriptions: existingSubs })
          );
        }

        res.json({
          ok: true,
          imported,
          skipped,
          total: Object.keys(data.sessions).length,
        });
      } catch (err) {
        res.status(500).json({ error: err.message });
      }
    }
  );
}