// Screenshot — capture the active tab, preview in the sidebar, then hand
// off to a full-tab editor only when the user asks for it. The old toolbar-
// dropdown flow auto-opened editor.html the instant a capture completed;
// that turned the editor tab into the ACTIVE tab, so any second click of
// the dropdown snapshotted the editor's still-blank canvas and every follow-
// up produced a white PNG. Sidebar-first breaks that loop entirely: the
// preview is served from a data URL inside the sidebar's own document, and
// the editor tab is opened only on an explicit "Open in editor" click.
//
// Flow:
//   panel invokes "capture" → api.captureTab → write PNG to per-add-on
//   scratch dir → return {name, dataUrl, width, height, host, bytes} to
//   panel → panel renders <img src="data:…"> in a preview area.
//   panel invokes "openInTab" → we stash the raw PNG in api.storage under
//   "__pending" and openTab("editor.html") — the editor's preload lets it
//   pull that entry out via silentmode.storage.get().

const fs = require("node:fs");
const path = require("node:path");

const MAX_RECENT  = 6;                     // ring size for the recent-captures list
const SCRATCH_DIR = "screenshot-scratch";  // sibling of the add-on's storage JSON

module.exports = {
  activate(api) {
    api.registerSidebarPanel({
      id: "main",
      title: "Screenshot",
      icon: "📸",
      page: "panel.html",
    });

    // Per-add-on scratch dir under <userData>/addons-data/. We don't touch
    // the add-on folder itself — editing it there would confuse users who
    // are inspecting the shipped source. api.folder = <userData>/addons/
    // screenshot/, so dirname twice lands on <userData>.
    const dataParent = path.dirname(path.join(api.folder, ".."));
    const scratchDir = path.join(dataParent, "addons-data", SCRATCH_DIR);
    try { fs.mkdirSync(scratchDir, { recursive: true }); }
    catch (e) { api.log("scratch mkdir failed:", e?.message); }

    // Region-select overlay source, loaded once at activation. Region mode
    // hands this to capture-tab, which injects it into the target tab and
    // awaits the {x,y,w,h} the overlay resolves with.
    let overlaySource = "";
    try { overlaySource = fs.readFileSync(path.join(api.folder, "panel-preload.js"), "utf8"); }
    catch (e) { api.log("panel-preload.js not readable:", e?.message); }

    function fileUrl(abs) {
      return "file:///" + abs.replace(/\\/g, "/").replace(/^\/+/, "").replace(/#/g, "%23").replace(/\?/g, "%3F");
    }
    function nowStamp() {
      const d = new Date();
      const pad = (n) => String(n).padStart(2, "0");
      return `${d.getFullYear()}${pad(d.getMonth()+1)}${pad(d.getDate())}-${pad(d.getHours())}${pad(d.getMinutes())}${pad(d.getSeconds())}`;
    }
    function pruneRecent(recent) {
      const alive = recent.filter((r) => { try { fs.accessSync(r.path); return true; } catch { return false; } });
      const trimmed = alive.slice(0, MAX_RECENT);
      const dropped = alive.slice(MAX_RECENT);
      for (const r of dropped) { try { fs.unlinkSync(r.path); } catch {} }
      return trimmed;
    }
    function writeScratch(dataUrl, name) {
      const m = /^data:image\/png;base64,(.+)$/.exec(String(dataUrl));
      if (!m) throw new Error("expected image/png data URL from capture");
      const buf = Buffer.from(m[1], "base64");
      const file = path.join(scratchDir, name);
      fs.writeFileSync(file, buf);
      return { path: file, bytes: buf.length };
    }
    function readAsDataUrl(absPath) {
      const buf = fs.readFileSync(absPath);
      return `data:image/png;base64,${buf.toString("base64")}`;
    }

    // panel invokes "capture": take the shot, write to scratch, hand the
    // data URL straight back so the sidebar can preview it immediately.
    api.onMessage("capture", async (payload) => {
      const mode = String(payload && payload.mode || "visible");
      if (mode !== "visible" && mode !== "full" && mode !== "region") {
        throw new Error(`unknown capture mode: ${mode}`);
      }
      const opts = { mode, format: "png" };
      if (mode === "region") opts.overlaySource = overlaySource;
      const cap = await api.captureTab(opts);
      if (cap.cancelled) { api.log(`region capture cancelled`); return { ok: false, cancelled: true }; }
      const name = `screenshot-${nowStamp()}${mode === "full" ? "-fullpage" : mode === "region" ? "-region" : ""}.png`;
      const written = writeScratch(cap.dataUrl, name);
      let recent = api.storage.get("recent", []);
      if (!Array.isArray(recent)) recent = [];
      recent.unshift({ id: name, name, path: written.path, bytes: written.bytes, at: Date.now(), mode });
      recent = pruneRecent(recent);
      api.storage.set("recent", recent);
      api.log(`captured ${mode} → ${name} (${written.bytes} bytes)`);
      return {
        ok: true, name, mode,
        dataUrl: cap.dataUrl,
        width: cap.width, height: cap.height,
        host: cap.host, bytes: written.bytes,
      };
    });

    // panel invokes "openInTab" once the user is happy with the preview.
    // We rewrite __pending fresh (the editor consumes it on load) so the
    // editor is always populated from the most-recent capture — even if a
    // prior editor tab already drained the pending entry.
    api.onMessage("openInTab", (payload) => {
      const wantedName = payload && payload.name ? String(payload.name) : "";
      let recent = api.storage.get("recent", []);
      if (!Array.isArray(recent)) recent = [];
      recent = pruneRecent(recent);
      api.storage.set("recent", recent);
      const hit = wantedName ? recent.find((r) => r.id === wantedName) : recent[0];
      if (!hit) throw new Error("no capture to open — take one first");
      const dataUrl = readAsDataUrl(hit.path);
      api.storage.set("__pending", { name: hit.name, dataUrl, at: Date.now() });
      api.openTab("editor.html", { query: { name: hit.name } });
      api.log(`openInTab → editor.html?name=${hit.name}`);
      return { ok: true, name: hit.name };
    });

    // Read the ring for a "recent captures" strip in the sidebar. Bytes are
    // reported; the actual images are pulled through "getBytes" on demand
    // so we don't ship every thumbnail through IPC on every panel open.
    api.onMessage("listRecent", () => {
      let recent = api.storage.get("recent", []);
      if (!Array.isArray(recent)) recent = [];
      recent = pruneRecent(recent);
      api.storage.set("recent", recent);
      return recent.map((r) => ({ id: r.id, name: r.name, bytes: r.bytes, at: r.at, mode: r.mode }));
    });

    // Panel asks for a specific past capture's bytes so it can preview it.
    api.onMessage("getBytes", (payload) => {
      const wantedName = String(payload && payload.name || "");
      const recent = api.storage.get("recent", []) || [];
      const hit = recent.find((r) => r.id === wantedName);
      if (!hit) throw new Error(`no recent capture "${wantedName}"`);
      return { name: hit.name, dataUrl: readAsDataUrl(hit.path), bytes: hit.bytes, at: hit.at, mode: hit.mode };
    });

    api.onMessage("clearRecent", (payload) => {
      const wantedName = payload && payload.name ? String(payload.name) : "";
      let recent = api.storage.get("recent", []) || [];
      if (wantedName) {
        const hit = recent.find((r) => r.id === wantedName);
        if (hit) { try { fs.unlinkSync(hit.path); } catch {} }
        recent = recent.filter((r) => r.id !== wantedName);
      } else {
        for (const r of recent) { try { fs.unlinkSync(r.path); } catch {} }
        recent = [];
      }
      api.storage.set("recent", recent);
      return { ok: true };
    });

    api.log("registered screenshot v0.3.0 sidebar panel");
  },
};