import { readdirSync, readFileSync } from "node:fs";
import { fileURLToPath, pathToFileURL } from "node:url";
import { ESLint, type Linter } from "eslint";
import prettierConfig from "eslint-config-prettier";
import ts from "typescript";
import tseslint from "typescript-eslint";
import { describe, expect, it } from "vitest";

// The gate register (docs/gates.md) is held to the EFFECTIVE configuration (E32). A narrowing that
// is not on the register fails here — a rule switched off for a scope, a weak compiler flag, a ruff
// ignore, a knip exclusion, an accepted CVE. So "the gate checks X" is a claim this test verifies,
// not one a comment makes. (The comment that claimed the React Compiler's rules "are also linted"
// stood for months while the rule that would have said so was off.)
//
// Each narrowing is a (scope, id) pair; the register must hold a table row whose first cell is the
// scope and which names the id in backticks.

const REPO = fileURLToPath(new URL("../../../", import.meta.url));
const FRONTEND = `${REPO}frontend/`;
const read = (path: string) => readFileSync(REPO + path, "utf8");

/** register scope → every backticked id on its rows. */
function register(): Map<string, Set<string>> {
  const rows = new Map<string, Set<string>>();
  for (const line of read("docs/gates.md").split("\n")) {
    if (!line.startsWith("|") || /^\|(\s*-+\s*\|)+\s*$/.test(line)) continue; // not the |---| rule
    const scope = line.split("|")[1]!.trim();
    const ids = rows.get(scope) ?? new Set<string>();
    for (const m of line.matchAll(/`([^`]+)`/g)) ids.add(m[1]!);
    rows.set(scope, ids);
  }
  return rows;
}

function missingFrom(found: [scope: string, id: string][]): string[] {
  const reg = register();
  return found.filter(([scope, id]) => !reg.get(scope)?.has(id)).map(([s, id]) => `${s}: ${id}`);
}

const jsonc = (path: string) => {
  const { config, error } = ts.parseConfigFileTextToJson(path, read(path));
  if (error)
    throw new Error(`${path}: ${ts.flattenDiagnosticMessageText(error.messageText, "\n")}`);
  return config as Record<string, unknown>;
};

// --- ESLint ---------------------------------------------------------------------------------------

type Rules = Partial<Linter.RulesRecord>;
const severity = (v: Linter.RuleEntry | undefined): number => {
  if (v === undefined) return -1; // not applied at all
  const s = Array.isArray(v) ? v[0] : v;
  return s === 2 || s === "error" ? 2 : s === 1 || s === "warn" ? 1 : 0;
};
// Formatting is Prettier's (its own lane): the rules eslint-config-prettier switches off are not a
// narrowing of anything.
const PRETTIER_OFF = new Set(
  Object.entries(prettierConfig.rules ?? {})
    .filter(([, v]) => severity(v as Linter.RuleEntry) === 0)
    .map(([r]) => r),
);
// …and the core rules typescript-eslint's compatibility layer switches off for TS files because the
// type checker reports them itself (no-undef, no-redeclare, no-dupe-keys, …).
const TSC_OWNED = new Set(
  Object.entries(tseslint.configs.eslintRecommended.rules ?? {})
    .filter(([, v]) => severity(v as Linter.RuleEntry) === 0)
    .map(([r]) => r),
);
const family = (rule: string) => (rule.includes("/") ? `${rule.split("/")[0]}/*` : rule);

// Each scope is checked through a sample file's EFFECTIVE config (what a rule family not applied there
// means), and every config block that targets files is checked on its own (below) — so a block no
// sample reaches fails rather than passing unseen (E32 review: a narrowing scoped to any other file
// changed none of the sampled configs and needed no row).
const SCOPES: Record<string, string> = {
  src: "src/components/Feed.tsx",
  "src/lib": "src/lib/format.ts",
  "lib/http.ts": "src/lib/http.ts",
  "lib/api/core.ts": "src/lib/api/core.ts",
  "lib/messagesSocket.ts": "src/lib/messagesSocket.ts",
  "src tests": "src/components/Feed.ytsort.dom.test.tsx",
  "FocusSafeButton.tsx": "src/components/ui/FocusSafeButton.tsx",
  "AnchoredPopover.tsx": "src/components/ui/AnchoredPopover.tsx",
  "design-lab": "src/design-lab/batchA.tsx",
  e2e: "e2e/nav.spec.ts",
  "ts configs": "vite.config.ts",
  "js configs": "eslint.config.js",
};

/** A flat-config `files` glob as a regex — the shapes this config uses: `**`, `*`, `{a,b}`. */
function globRegex(glob: string): RegExp {
  let out = "";
  for (let i = 0; i < glob.length; i++) {
    const c = glob[i]!;
    if (glob.startsWith("**/", i)) {
      out += "(?:.*/)?";
      i += 2;
    } else if (c === "*") out += "[^/]*";
    else if (c === "{") {
      const end = glob.indexOf("}", i);
      out += `(?:${glob
        .slice(i + 1, end)
        .split(",")
        .join("|")})`;
      i = end;
    } else out += /[.+?^$()|[\]\\]/.test(c) ? `\\${c}` : c;
  }
  return new RegExp(`^${out}$`);
}

type Block = Linter.Config & { files?: (string | string[])[]; ignores?: string[] };
const blocks = async (): Promise<Block[]> =>
  ((await import(pathToFileURL(`${FRONTEND}eslint.config.js`).href)) as { default: Block[] })
    .default;

// A rule option whose key says it lets something through (`allowShortCircuit`,
// `allowForKnownSafeCalls`, `ignoreRestSiblings`, `exceptAfterSingleLine`) narrows the rule, and a
// `no-restricted-*` list re-declared for a scope narrows it by every entry it leaves out.
const RELAXING_KEY = /^(allow|ignore|except)/;
const relaxes = (options: unknown[]): boolean =>
  options.some(
    (o) =>
      o !== null &&
      typeof o === "object" &&
      Object.entries(o).some(
        ([k, v]) => RELAXING_KEY.test(k) && v !== false && !(Array.isArray(v) && v.length === 0),
      ),
  );
function restrictedEntries(entry: Linter.RuleEntry | undefined): Set<string> {
  const opts: unknown[] = Array.isArray(entry) ? entry.slice(1) : [];
  const flat = opts.flatMap((o) => {
    if (o === null || typeof o !== "object" || Array.isArray(o)) return [o];
    const { paths = [], patterns = [] } = o as { paths?: unknown[]; patterns?: unknown[] };
    return "paths" in o || "patterns" in o ? [...paths, ...patterns] : [o];
  });
  return new Set(flat.map((e) => JSON.stringify(e)));
}

async function eslintNarrowings(): Promise<[string, string][]> {
  const eslint = new ESLint({ cwd: FRONTEND });
  const rules: Record<string, Rules> = {};
  for (const [scope, file] of Object.entries(SCOPES))
    rules[scope] = ((await eslint.calculateConfigForFile(file)) as Linter.Config).rules ?? {};
  const src = rules.src!;
  const ignorable = (rule: string, all: Rules) =>
    PRETTIER_OFF.has(rule) ||
    TSC_OWNED.has(rule) ||
    // a core rule off because its typescript-eslint twin replaces it is reported as the twin
    (!rule.includes("/") && `@typescript-eslint/${rule}` in all);
  const found: [string, string][] = [];
  // src: everything at off or warn, and every rule whose options let something through
  for (const [rule, v] of Object.entries(src)) {
    if (ignorable(rule, src)) continue;
    if (severity(v) < 2 || (Array.isArray(v) && relaxes(v.slice(1)))) found.push(["src", rule]);
  }
  // every other scope: what is WEAKER there than in src (a rule family not applied at all is one
  // id). A src rule at warn counts too: switched off for a scope, it is narrowed there.
  for (const scope of Object.keys(SCOPES).filter((s) => s !== "src")) {
    const ids = new Set<string>();
    for (const [rule, v] of Object.entries(src)) {
      if (ignorable(rule, src) || severity(v) === 0) continue;
      const there = severity(rules[scope]![rule]);
      if (there < severity(v)) ids.add(there < 0 ? family(rule) : rule);
    }
    for (const id of ids) found.push([scope, id]);
  }
  // every config block: a global `ignores` is a narrowing everywhere; one that targets files must
  // reach a sample, and what it re-declares is held to src
  for (const block of await blocks()) {
    if (!block.files) {
      if (Object.keys(block).join() === "ignores")
        for (const ignored of block.ignores ?? []) found.push(["everywhere", ignored]);
      continue;
    }
    const globs = block.files.flat().map(globRegex);
    const scope = Object.keys(SCOPES).find((s) => globs.some((g) => g.test(SCOPES[s]!)));
    if (!scope) {
      found.push(["unsampled block", block.files.flat().join(", ")]);
      continue;
    }
    if (block.ignores?.length) found.push([scope, `ignores: ${block.ignores.join(", ")}`]);
    for (const [rule, v] of Object.entries(block.rules ?? {})) {
      if (ignorable(rule, src)) continue;
      if (rule.includes("no-restricted-")) {
        const own = restrictedEntries(v);
        if ([...restrictedEntries(src[rule])].some((e) => !own.has(e))) found.push([scope, rule]);
      } else if (Array.isArray(v) && relaxes(v.slice(1))) found.push([scope, rule]);
    }
  }
  return found;
}

describe("the gate register (docs/gates.md)", () => {
  it("lists every ESLint rule narrowed, by scope", async () => {
    expect(missingFrom(await eslintNarrowings())).toEqual([]);
  }, 60_000);

  it("keeps --max-warnings 0, which is what makes a warn-level rule fail", () => {
    const pkg = JSON.parse(read("frontend/package.json")) as { scripts: Record<string, string> };
    expect(pkg.scripts.lint).toMatch(/--max-warnings 0\b/);
  });

  // --- TypeScript ---------------------------------------------------------------------------------
  const PROJECTS = [
    "frontend/tsconfig.json",
    "frontend/tsconfig.node.json",
    "frontend/e2e/tsconfig.json",
  ];
  const REQUIRED_ON = [
    "strict",
    "noUncheckedIndexedAccess",
    "noUnusedLocals",
    "noUnusedParameters",
    "noFallthroughCasesInSwitch",
  ];
  it.each(PROJECTS)("%s keeps the strict flags on", (path) => {
    const opts = jsonc(path).compilerOptions as Record<string, unknown>;
    expect(REQUIRED_ON.filter((flag) => opts[flag] !== true)).toEqual([]);
  });
  // `strict: true` is a bundle: a sub-flag set false beside it, an `extends` this test cannot see
  // through, or a narrowed `include` / an `exclude` weakens the project while the five flags above
  // still read true (E32 review).
  const STRICT_FAMILY = [
    "noImplicitAny",
    "strictNullChecks",
    "strictFunctionTypes",
    "strictBindCallApply",
    "strictPropertyInitialization",
    "noImplicitThis",
    "alwaysStrict",
    "useUnknownInCatchVariables",
    "strictBuiltinIteratorReturn",
  ];
  const INCLUDE: Record<string, string[]> = {
    "frontend/tsconfig.json": ["src"],
    "frontend/tsconfig.node.json": [
      "vite.config.ts",
      "vitest.config.ts",
      "reactPlugin.ts",
      "devOnlyGuard.ts",
      "playwright.config.ts",
      "postcss.config.js",
    ],
    "frontend/e2e/tsconfig.json": [".", "../playwright.config.ts"],
  };
  it("lists every weakening compiler flag", () => {
    const found: [string, string][] = [];
    for (const path of PROJECTS) {
      const cfg = jsonc(path);
      const opts = cfg.compilerOptions as Record<string, unknown>;
      if (opts.skipLibCheck === true) found.push(["all three projects", "skipLibCheck"]);
      for (const flag of STRICT_FAMILY) if (opts[flag] === false) found.push([path, flag]);
      for (const key of ["extends", "exclude", "files"]) if (key in cfg) found.push([path, key]);
      expect(cfg.include, path).toEqual(INCLUDE[path]);
    }
    expect(missingFrom(found)).toEqual([]);
  });
  it("type-checks every config file at the frontend root, or lists it", () => {
    const checked = new Set(INCLUDE["frontend/tsconfig.node.json"]);
    const roots = readdirSync(FRONTEND).filter((f) => /[.](ts|js|mjs|cjs)$/.test(f));
    const found = roots
      .filter((f) => !checked.has(f))
      .map((f): [string, string] => ["config files", `${f} — not type-checked`]);
    expect(missingFrom(found)).toEqual([]);
  });

  // --- Ruff -----------------------------------------------------------------------------------------
  // Ruff, pyright, pytest and knip are read as KEY whitelists: a key this test does not know (an
  // `extend-exclude`, a `lint.extend-ignore`, a narrowing `select`, a pyright `exclude`, a pytest
  // `-m "not slow"`, a knip `rules`) fails until someone decides whether it narrows (E32 review —
  // only `ignore` and the immutable calls used to be read).
  const tomlKeys = (toml: string) =>
    toml
      .split("\n")
      .map((l) => /^\s*([A-Za-z0-9_.-]+)\s*=/.exec(l)?.[1])
      .filter((k): k is string => k !== undefined);
  it("lists every ruff ignore and immutable call, and knows every key", () => {
    const toml = read("backend/ruff.toml");
    const list = (key: string) => {
      const m = new RegExp(`^${key}\\s*=\\s*\\[([^\\]]*)\\]`, "m").exec(toml);
      return m ? [...m[1]!.matchAll(/"([^"]+)"/g)].map((x) => x[1]!) : [];
    };
    expect(tomlKeys(toml).sort()).toEqual(
      ["extend-immutable-calls", "extend-select", "ignore", "line-length", "target-version"].sort(),
    );
    // the selection on top of ruff's defaults (E, F) — dropping one narrows the lane
    expect(list("extend-select")).toEqual([
      "LOG",
      "G",
      "T20",
      "TRY400",
      "TRY401",
      "S110",
      "S112",
      "BLE001",
      "RUF100",
      "PLW1510",
      "B",
    ]);
    const found: [string, string][] = [
      ...list("ignore").map((code): [string, string] => ["backend + scripts", code]),
      ...list("extend-immutable-calls").map((c): [string, string] => ["backend + scripts", c]),
    ];
    expect(missingFrom(found)).toEqual([]);
  });

  // --- basedpyright ---------------------------------------------------------------------------------
  const PYRIGHT_KEYS = [
    "include",
    "extraPaths",
    "typeCheckingMode",
    "pythonVersion",
    "pythonPlatform",
  ];
  it("lists the type-check mode, the baseline and every rule override, and knows every key", () => {
    const cfg = jsonc("backend/pyrightconfig.json");
    const found: [string, string][] = [];
    if (cfg.typeCheckingMode !== "all" && cfg.typeCheckingMode !== "strict")
      found.push(["backend/app + alembic", "typeCheckingMode"]);
    found.push(["backend/app + alembic", "baseline.json"]);
    const weak = [false, "none", "warning", "information", "hint"];
    for (const [key, value] of Object.entries(cfg))
      if (key.startsWith("report") && weak.includes(value as string | boolean))
        found.push(["backend/app + alembic", key]);
    expect(
      Object.keys(cfg).filter((k) => !k.startsWith("report") && !PYRIGHT_KEYS.includes(k)),
    ).toEqual([]);
    expect(cfg.include).toEqual(["app", "alembic"]); // tests/ out — its row says why
    expect(missingFrom(found)).toEqual([]);
  });

  // --- pytest ---------------------------------------------------------------------------------------
  it("keeps pytest strict: the whole tests/ tree, no selection, no warning filters, --strict-markers", () => {
    const ini = read("backend/pytest.ini");
    const keys = ini
      .split("\n")
      .filter((l) => !l.trim().startsWith("#"))
      .map((l) => /^([a-z_]+)\s*=\s*(.*)$/.exec(l))
      .filter((m) => m !== null);
    expect(Object.fromEntries(keys.map((m) => [m[1], m[2]!.trim()]))).toEqual({
      testpaths: "tests",
      pythonpath: ".",
      addopts: "-q -rs --strict-markers",
    });
  });

  // --- knip -----------------------------------------------------------------------------------------
  it("lists every knip production exclusion and every other key, and runs both modes", () => {
    const cfg = jsonc("frontend/knip.jsonc") as { project?: string[] } & Record<string, unknown>;
    const found: [string, string][] = (cfg.project ?? [])
      .filter((p) => p.startsWith("!"))
      .map((p): [string, string] => ["--production", p]);
    for (const key of Object.keys(cfg).filter(
      (k) => !["$schema", "project", "playwright"].includes(k),
    ))
      found.push(["knip", key]);
    expect(missingFrom(found)).toEqual([]);
    const pkg = JSON.parse(read("frontend/package.json")) as { scripts: Record<string, string> };
    expect(pkg.scripts.knip).toBe("knip && knip --production");
  });

  // --- accepted findings ----------------------------------------------------------------------------
  it("accepts a CVE only with a statement, an expiry, and a row", () => {
    const yaml = read(".trivyignore.yaml");
    const entries = yaml
      .split(/\n\s*- id:\s*/)
      .slice(1)
      .map((chunk) => ({
        id: chunk.split("\n")[0]!.trim(),
        statement: /\n\s*statement:\s*\S/.test(chunk),
        expires: /\n\s*expired_at:\s*\d{4}-\d{2}-\d{2}/.test(chunk),
      }));
    expect(entries.filter((e) => !e.statement || !e.expires).map((e) => e.id)).toEqual([]);
    const pipIgnores = read(".gitea/workflows/check.yml")
      .split("\n")
      .filter((l) => !l.trim().startsWith("#")) // the step's comment explains the flag; it is not one
      .flatMap((l) => [...l.matchAll(/--ignore-vuln[ =](\S+)/g)].map((m) => m[1]!));
    const found = [...entries.map((e) => e.id), ...pipIgnores].map((id): [string, string] => [
      "accepted",
      id,
    ]);
    expect(missingFrom(found)).toEqual([]);
  });
});