import * as assert from "assert";
import * as fs from "fs";
import * as path from "path";
import * as vscode from "vscode";
import type { CowritingApi } from "../../../src/extension";

const WS = process.env.E2E_WORKSPACE!;
const DOC_REL = "docs/diffview.md";

async function openDoc(): Promise<vscode.TextDocument> {
  const uri = vscode.Uri.file(path.join(WS, DOC_REL));
  const doc = await vscode.workspace.openTextDocument(uri);
  await vscode.window.showTextDocument(doc);
  return doc;
}
async function getApi(): Promise<CowritingApi> {
  const ext = vscode.extensions.getExtension("benstull.vscode-cowriting-plugin")!;
  const api = (await ext.activate()) as CowritingApi;
  assert.ok(api?.diffViewController, "extension exports diffViewController");
  return api;
}
const settle = () => new Promise((r) => setTimeout(r, 300));

// Order-dependent (F2–F4 pattern): later tests consume earlier state. Owns
// docs/diffview.md exclusively.
suite("F6 diff-view toggle (host E2E — programmatic seam ingress, no LLM)", () => {
  const TARGET = "A target sentence Claude will rewrite via the seam.";
  const REPLACEMENT = "A SENTENCE CLAUDE REWROTE via the seam.";

  test("opening a tracked doc captures an `opened` baseline equal to the buffer (INV-18)", async () => {
    const doc = await openDoc();
    const api = await getApi();
    // renderIfOpen on open already called ensureBaseline; assert it captured.
    const baseline = api.diffViewController.getBaseline(DOC_REL);
    assert.ok(baseline, "baseline captured on first sight");
    assert.strictEqual(baseline!.reason, "opened");
    assert.strictEqual(baseline!.text, doc.getText(), "baseline = open-time buffer");
  });

  test("toggle opens a diff tab (original scheme cowriting-baseline) over the live doc (PUC-1)", async () => {
    const api = await getApi();
    assert.strictEqual(api.diffViewController.isDiffOpen(DOC_REL), false, "no diff open yet");
    await vscode.commands.executeCommand("cowriting.toggleDiffView");
    await settle();
    assert.strictEqual(api.diffViewController.isDiffOpen(DOC_REL), true, "diff tab open");
    // The active tab is a TextDiff whose original is the baseline scheme.
    const active = vscode.window.tabGroups.activeTabGroup.activeTab;
    assert.ok(active && active.input instanceof vscode.TabInputTextDiff, "active tab is a diff");
    assert.strictEqual(
      (active!.input as vscode.TabInputTextDiff).original.scheme,
      "cowriting-baseline",
      "left side served by the baseline provider",
    );
  });

  test("typing leaves the baseline unchanged while the buffer diverges", async () => {
    const doc = await openDoc();
    const api = await getApi();
    const before = api.diffViewController.getBaseline(DOC_REL)!.text;
    const edit = new vscode.WorkspaceEdit();
    edit.insert(doc.uri, new vscode.Position(0, 0), "OPERATOR ADDED LINE\n");
    assert.ok(await vscode.workspace.applyEdit(edit), "operator edit applied");
    await settle();
    assert.strictEqual(api.diffViewController.getBaseline(DOC_REL)!.text, before, "baseline unchanged by typing");
    assert.notStrictEqual(doc.getText(), before, "buffer diverged");
  });

  test("accepting a proposal advances the baseline past the landed text (PUC-2, INV-18)", async () => {
    const doc = await openDoc();
    const api = await getApi();
    const start = doc.getText().indexOf(TARGET);
    assert.ok(start >= 0, "fixture contains the target");
    const id = await vscode.commands.executeCommand<string>("cowriting.proposeAgentEdit", {
      uri: doc.uri.toString(),
      start,
      end: start + TARGET.length,
      newText: REPLACEMENT,
      model: "sonnet",
      sessionId: "e2e-diff",
      turnId: "turn-d1",
    });
    assert.ok(id, "propose returns an id");
    assert.ok(await api.proposalController.acceptById(DOC_REL, id!), "accept applies via the seam");
    await settle();
    const baseline = api.diffViewController.getBaseline(DOC_REL)!;
    assert.strictEqual(baseline.reason, "machine-landing", "baseline advanced on the landing");
    assert.ok(baseline.text.includes(REPLACEMENT), "landed text is in the baseline (won't show as a change)");
    assert.ok(!baseline.text.includes(TARGET), "old target gone from the baseline too");
    assert.strictEqual(baseline.text, doc.getText(), "baseline == buffer right after the landing");
  });

  test("an operator edit after the landing makes baseline ≠ buffer (the operator delta)", async () => {
    const doc = await openDoc();
    const api = await getApi();
    const edit = new vscode.WorkspaceEdit();
    edit.insert(doc.uri, new vscode.Position(0, 0), "POST-LANDING OPERATOR LINE\n");
    assert.ok(await vscode.workspace.applyEdit(edit));
    await settle();
    assert.notStrictEqual(
      api.diffViewController.getBaseline(DOC_REL)!.text,
      doc.getText(),
      "operator changes show against the advanced baseline",
    );
  });

  test("pin resets the baseline to now: baseline == buffer, reason pinned (PUC-3)", async () => {
    const doc = await openDoc();
    const api = await getApi();
    await vscode.commands.executeCommand("cowriting.pinDiffBaseline");
    await settle();
    const baseline = api.diffViewController.getBaseline(DOC_REL)!;
    assert.strictEqual(baseline.reason, "pinned");
    assert.strictEqual(baseline.text, doc.getText(), "pinned baseline == current buffer (diff empties)");
  });

  test("the baseline is persisted on disk under the storage dir with the expected content (PUC-4)", async () => {
    const api = await getApi();
    const p = api.diffViewController.baselineFilePath(DOC_REL);
    assert.ok(p, "storage-backed baseline path is available");
    assert.ok(fs.existsSync(p!), `baseline file exists at ${p}`);
    const onDisk = JSON.parse(fs.readFileSync(p!, "utf8"));
    assert.strictEqual(onDisk.docPath, DOC_REL);
    assert.strictEqual(onDisk.reason, "pinned", "last epoch (pin) persisted");
    assert.strictEqual(onDisk.text, api.diffViewController.getBaseline(DOC_REL)!.text, "on-disk == in-memory");
    // INV-19: nothing leaked into the repo's .threads sidecar tree.
    assert.ok(!p!.includes(`${path.sep}.threads${path.sep}`), "baseline is NOT in the sidecar tree");
  });

  test("toggle again closes the diff tab and reveals the normal editor (PUC-1)", async () => {
    const api = await getApi();
    if (!api.diffViewController.isDiffOpen(DOC_REL)) {
      await vscode.commands.executeCommand("cowriting.toggleDiffView");
      await settle();
    }
    assert.strictEqual(api.diffViewController.isDiffOpen(DOC_REL), true, "diff open before close");
    await vscode.commands.executeCommand("cowriting.toggleDiffView");
    await settle();
    assert.strictEqual(api.diffViewController.isDiffOpen(DOC_REL), false, "diff tab closed");
    // "Normal editor is back": the file is the active text editor, and no
    // baseline-diff tab for it remains in any group.
    assert.strictEqual(
      vscode.window.activeTextEditor?.document.uri.toString(),
      vscode.Uri.file(path.join(WS, DOC_REL)).toString(),
      "the normal editor for the doc is active after closing the diff",
    );
  });

  test("toggling on an untracked doc warns and opens no diff (PUC-5)", async () => {
    await getApi();
    const untracked = await vscode.workspace.openTextDocument({ content: "scratch", language: "markdown" });
    await vscode.window.showTextDocument(untracked);
    await settle();
    await vscode.commands.executeCommand("cowriting.toggleDiffView");
    await settle();
    // No baseline-diff tab for an untitled doc anywhere.
    const anyDiff = vscode.window.tabGroups.all.some((g) =>
      g.tabs.some(
        (t) =>
          t.input instanceof vscode.TabInputTextDiff &&
          t.input.original.scheme === "cowriting-baseline" &&
          t.input.modified.toString() === untracked.uri.toString(),
      ),
    );
    assert.strictEqual(anyDiff, false, "no diff opened for the untracked doc");
  });
});