// IMP-42 u4 — Source-slice coverage for the unconditional handleGenerate
// DIAG console.log on the frontend → backend boundary (issue #71).
//
// Scope (Stage 2 unit u4 contract):
//   1) A single `console.log("[DIAG raw overrides]", ...)` call exists
//      inside handleGenerate and precedes the runPipeline call site.
//   2) The DIAG call is unconditional — not wrapped in `if (...)` / `?:` /
//      env-var gate / `__DEV__`-style guard. "Silence is the bug" per
//      Stage 1 scope-lock (Codex #3) and the Step 13 backend mirror
//      already landed in u3.
//   3) The DIAG payload carries shape-only metadata — uploaded file name
//      and the override payload object — without referencing raw MDX
//      content or any other sample-specific identifier (RULE 0).
//
// Why source-slice (per Stage 2 plan): Home.tsx handleGenerate is wired to
// React state, toast, and a 700-line component tree; the cheapest way to
// pin a single-line surface and prove placement relative to runPipeline is
// to read the source and assert ordering. No React rendering, no fetch
// mock, no DOM. Mirrors the existing pure-helper pattern in
// tests/imp41_application_mode.test.ts.

import { describe, it, expect } from "vitest";
import { readFileSync } from "node:fs";
import { resolve } from "node:path";

const HOME_TSX_PATH = resolve(__dirname, "..", "src", "pages", "Home.tsx");
const HOME_TSX_SOURCE = readFileSync(HOME_TSX_PATH, "utf-8");

// Locate the handleGenerate callback body. The closing brace of
// useCallback's `async () => { ... }` is the next line whose indent matches
// the opening `useCallback(async () => {` exactly — but a simpler proxy is
// "from the handleGenerate keyword to the next useCallback declaration or
// the end-of-file." This is sufficient to scope every assertion below to
// the right function body.
function sliceHandleGenerateBody(source: string): string {
  const startMarker = "const handleGenerate = useCallback(async () =>";
  const startIdx = source.indexOf(startMarker);
  if (startIdx === -1) {
    throw new Error("handleGenerate declaration not found in Home.tsx");
  }
  // End at the next top-level `const ` that begins a new useCallback /
  // useMemo / hook binding. handleGenerate is followed by additional
  // hooks (handleFileUpload sibling pattern); slicing to the next
  // declaration is more than enough to capture the full body.
  const afterStart = source.slice(startIdx + startMarker.length);
  const nextDeclIdx = afterStart.search(/\n {2}const [A-Za-z]/);
  return nextDeclIdx === -1 ? afterStart : afterStart.slice(0, nextDeclIdx);
}

const HANDLE_GENERATE_BODY = sliceHandleGenerateBody(HOME_TSX_SOURCE);

describe("handleGenerate [DIAG raw overrides] (IMP-42 u4)", () => {
  it("emits exactly one console.log labelled '[DIAG raw overrides]' inside handleGenerate", () => {
    const matches = HANDLE_GENERATE_BODY.match(
      /console\.log\(\s*"\[DIAG raw overrides\]"/g,
    );
    expect(matches).not.toBeNull();
    // Exactly one DIAG site per Stage 2 contract — multiple calls would
    // either be a copy-paste regression or evidence that the helper
    // moved without removing the old site.
    expect(matches?.length).toBe(1);
  });

  it("places the DIAG console.log before the runPipeline call site", () => {
    const diagIdx = HANDLE_GENERATE_BODY.indexOf('console.log("[DIAG raw overrides]"');
    const runPipelineIdx = HANDLE_GENERATE_BODY.indexOf(
      "runPipeline(state.uploadedFile, overrides)",
    );
    expect(diagIdx).toBeGreaterThan(-1);
    expect(runPipelineIdx).toBeGreaterThan(-1);
    expect(diagIdx).toBeLessThan(runPipelineIdx);
  });

  it("is unconditional — no env-var gate or if-guard wraps the DIAG call", () => {
    // Slice the 80 chars immediately preceding the DIAG console.log and
    // confirm none of the common gating patterns appear directly above.
    const diagIdx = HANDLE_GENERATE_BODY.indexOf('console.log("[DIAG raw overrides]"');
    const preface = HANDLE_GENERATE_BODY.slice(Math.max(0, diagIdx - 200), diagIdx);
    // Stage 1 contract: silence is the bug. Any gate here is a regression.
    expect(preface).not.toMatch(/if\s*\([^)]*\)\s*$/m);
    expect(preface).not.toMatch(/process\.env/);
    expect(preface).not.toMatch(/import\.meta\.env/);
    expect(preface).not.toMatch(/__DEV__/);
    expect(preface).not.toMatch(/DIAG_VERBOSE/i);
    expect(preface).not.toMatch(/DEBUG/);
  });

  it("forwards the file name and overrides object as shape-only payload", () => {
    // The DIAG payload must include the uploaded file name (so the user
    // can correlate the log line with the MDX they uploaded) and the
    // overrides object (so the user can see what crossed the wire).
    // It must NOT spread MDX text content or any other large blob —
    // sample-agnostic and reviewable in a single log line.
    const diagIdx = HANDLE_GENERATE_BODY.indexOf('console.log("[DIAG raw overrides]"');
    const window = HANDLE_GENERATE_BODY.slice(diagIdx, diagIdx + 300);
    // Both fields appear in the payload object literal.
    expect(window).toMatch(/file:\s*state\.uploadedFile\.name/);
    expect(window).toMatch(/\boverrides\b/);
    // Sanity: the payload does not pass MDX raw content / a File blob.
    expect(window).not.toMatch(/mdxContent|rawMdx|normalizedContent/);
  });

  it("runs after flushUserOverrides() so the persisted PUT is already committed", () => {
    // Ordering invariant from IMP-52 u10 (already in place):
    //   flushUserOverrides() → DIAG → runPipeline
    // Asserts the DIAG sits between the flush and the network call so the
    // logged overrides match what backend reads from disk.
    const flushIdx = HANDLE_GENERATE_BODY.indexOf("await flushUserOverrides()");
    const diagIdx = HANDLE_GENERATE_BODY.indexOf('console.log("[DIAG raw overrides]"');
    const runPipelineIdx = HANDLE_GENERATE_BODY.indexOf(
      "runPipeline(state.uploadedFile, overrides)",
    );
    expect(flushIdx).toBeGreaterThan(-1);
    expect(diagIdx).toBeGreaterThan(flushIdx);
    expect(diagIdx).toBeLessThan(runPipelineIdx);
  });
});