// Runs the whole test suite once and renders reports/test-report.md: a summary,
// a describe-grouped inventory, and a coverage table.
// The report is written even when tests fail, and the process exits with the
// test run's own status so CI can gate on it.
// Split into run -> parse -> render so a future CI job can reuse parse+render
// on artifacts it already produced.

import { existsSync, mkdirSync, readFileSync, writeFileSync } from "node:fs";
import { XMLParser } from "fast-xml-parser";

const REPORTS_DIR = "reports";
const JUNIT_PATH = `${REPORTS_DIR}/junit.xml`;
const LCOV_PATH = "coverage/lcov.info";
const REPORT_PATH = `${REPORTS_DIR}/test-report.md`;

type TestStatus = "passed" | "failed" | "todo";

interface TestCase {
  name: string;
  status: TestStatus;
  time: number;
  message?: string;
}

interface Suite {
  name: string;
  suites: Suite[];
  tests: TestCase[];
}

interface Junit {
  totals: { tests: number; failures: number; skipped: number; time: number };
  files: Suite[];
}

interface FileCoverage {
  file: string;
  linesFound: number;
  linesHit: number;
  funcsFound: number;
  funcsHit: number;
  uncovered: number[];
}

// --- run ---

function runTests(): number {
  mkdirSync(REPORTS_DIR, { recursive: true });
  const proc = Bun.spawnSync(
    [
      "bun",
      "test",
      "--coverage",
      "--coverage-reporter=lcov",
      "--reporter=junit",
      `--reporter-outfile=${JUNIT_PATH}`,
    ],
    { stdout: "inherit", stderr: "inherit" },
  );
  return proc.exitCode ?? 1;
}

// --- parse ---

const xml = new XMLParser({
  ignoreAttributes: false,
  attributeNamePrefix: "@_",
  isArray: (name) => name === "testsuite" || name === "testcase",
});

function parseJunit(path: string): Junit {
  const root = xml.parse(readFileSync(path, "utf8")).testsuites;
  return {
    totals: {
      tests: Number(root["@_tests"] ?? 0),
      failures: Number(root["@_failures"] ?? 0),
      skipped: Number(root["@_skipped"] ?? 0),
      time: Number(root["@_time"] ?? 0),
    },
    files: (root.testsuite ?? []).map(parseSuite),
  };
}

// biome-ignore lint/suspicious/noExplicitAny: raw fast-xml-parser nodes are untyped
function parseSuite(node: any): Suite {
  return {
    name: node["@_name"] ?? "(unnamed)",
    suites: (node.testsuite ?? []).map(parseSuite),
    tests: (node.testcase ?? []).map(parseCase),
  };
}

// biome-ignore lint/suspicious/noExplicitAny: raw fast-xml-parser nodes are untyped
function parseCase(node: any): TestCase {
  const name = node["@_name"] ?? "(unnamed)";
  const time = Number(node["@_time"] ?? 0);
  if (node.failure !== undefined) {
    const message = node.failure["@_message"] ?? node.failure["#text"] ?? "";
    return { name, status: "failed", time, message: String(message) };
  }
  if (node.skipped !== undefined) {
    return { name, status: "todo", time };
  }
  return { name, status: "passed", time };
}

function parseLcov(path: string): FileCoverage[] {
  if (!existsSync(path)) {
    return [];
  }
  const records: FileCoverage[] = [];
  let current: FileCoverage | null = null;
  for (const line of readFileSync(path, "utf8").split("\n")) {
    if (line.startsWith("SF:")) {
      current = {
        file: line.slice(3).trim(),
        linesFound: 0,
        linesHit: 0,
        funcsFound: 0,
        funcsHit: 0,
        uncovered: [],
      };
    } else if (!current) {
      // Skip anything before the first source record.
    } else if (line.startsWith("FNF:")) {
      current.funcsFound = Number(line.slice(4));
    } else if (line.startsWith("FNH:")) {
      current.funcsHit = Number(line.slice(4));
    } else if (line.startsWith("DA:")) {
      const [lineNo, hits] = line.slice(3).split(",");
      current.linesFound++;
      if (Number(hits) > 0) {
        current.linesHit++;
      } else {
        current.uncovered.push(Number(lineNo));
      }
    } else if (line.startsWith("end_of_record")) {
      records.push(current);
      current = null;
    }
  }
  return records;
}

// --- render ---

const ICON: Record<TestStatus, string> = {
  passed: "✅",
  failed: "❌",
  todo: "⏭️",
};

function pct(hit: number, found: number): string {
  if (found === 0) {
    return "—";
  }
  return `${((hit / found) * 100).toFixed(1)}% (${hit}/${found})`;
}

// Collapse consecutive line numbers into ranges, e.g. 33,34,...,40 -> "33-40".
function ranges(lines: number[]): string {
  if (lines.length === 0) {
    return "—";
  }
  const sorted = [...lines].sort((a, b) => a - b);
  const out: string[] = [];
  let start = sorted[0];
  let prev = sorted[0];
  for (const n of sorted.slice(1)) {
    if (n === prev + 1) {
      prev = n;
      continue;
    }
    out.push(start === prev ? `${start}` : `${start}-${prev}`);
    start = n;
    prev = n;
  }
  out.push(start === prev ? `${start}` : `${start}-${prev}`);
  return out.join(", ");
}

function renderSuite(suite: Suite, depth: number, lines: string[]): void {
  const indent = "  ".repeat(depth);
  for (const child of suite.suites) {
    lines.push(`${indent}- **${child.name}**`);
    renderSuite(child, depth + 1, lines);
  }
  for (const test of suite.tests) {
    const timing =
      test.status === "passed" && test.time > 0 ? ` _(${(test.time * 1000).toFixed(0)}ms)_` : "";
    lines.push(`${indent}- ${ICON[test.status]} ${test.name}${timing}`);
    if (test.status === "failed" && test.message) {
      lines.push(`${indent}  - \`${test.message.replace(/`/g, "'").replace(/\n/g, " ")}\``);
    }
  }
}

function renderReport(junit: Junit, coverage: FileCoverage[], meta: string): string {
  const { tests, failures, skipped, time } = junit.totals;
  const passed = tests - failures - skipped;
  const result = failures === 0 ? "✅ All passing" : `❌ ${failures} failing`;

  const lines: string[] = [];
  lines.push("# Test Report", "", `_${meta}_`, "");

  lines.push("## Summary", "");
  lines.push("| Metric | Value |", "| --- | --- |");
  lines.push(`| Result | ${result} |`);
  lines.push(`| Passed | ${passed} |`);
  lines.push(`| Failed | ${failures} |`);
  lines.push(`| Todo | ${skipped} |`);
  lines.push(`| Total | ${tests} |`);
  lines.push(`| Duration | ${time.toFixed(2)}s |`, "");

  lines.push("## Test inventory", "");
  for (const file of junit.files) {
    lines.push(`### \`${file.name}\``, "");
    renderSuite(file, 0, lines);
    lines.push("");
  }

  lines.push("## Coverage", "");
  if (coverage.length === 0) {
    lines.push("_No coverage data found._", "");
  } else {
    lines.push("| File | Lines | Functions | Uncovered |", "| --- | --- | --- | --- |");
    const total = { linesFound: 0, linesHit: 0, funcsFound: 0, funcsHit: 0 };
    for (const file of coverage) {
      total.linesFound += file.linesFound;
      total.linesHit += file.linesHit;
      total.funcsFound += file.funcsFound;
      total.funcsHit += file.funcsHit;
      lines.push(
        `| \`${file.file}\` | ${pct(file.linesHit, file.linesFound)} | ${pct(file.funcsHit, file.funcsFound)} | ${ranges(file.uncovered)} |`,
      );
    }
    lines.push(
      `| **Total** | **${pct(total.linesHit, total.linesFound)}** | **${pct(total.funcsHit, total.funcsFound)}** | |`,
      "",
    );
    lines.push(
      "> Coverage instruments in-process code only; code exercised solely through a subprocess (such as the CLI entry point) is not counted.",
      "",
    );
  }

  return lines.join("\n");
}

// --- main ---

function gitSha(): string {
  const proc = Bun.spawnSync(["git", "rev-parse", "--short", "HEAD"]);
  return proc.exitCode === 0 ? proc.stdout.toString().trim() : "unknown";
}

const exitCode = runTests();
mkdirSync(REPORTS_DIR, { recursive: true });

const meta = `Generated ${new Date().toISOString()} · commit ${gitSha()} · whole repo`;

if (!existsSync(JUNIT_PATH)) {
  writeFileSync(
    REPORT_PATH,
    `# Test Report\n\n_${meta}_\n\nThe test run produced no JUnit output; it likely failed to start.\n`,
  );
  console.error(`Test run produced no JUnit output. Wrote a stub to ${REPORT_PATH}.`);
  process.exit(exitCode || 1);
}

writeFileSync(REPORT_PATH, renderReport(parseJunit(JUNIT_PATH), parseLcov(LCOV_PATH), meta));
console.log(`Wrote ${REPORT_PATH}`);
process.exit(exitCode);