#!/usr/bin/env node
// Renders a Vitest coverage-summary.json into either a shields.io badge URL
// (default) or a sticky PR-comment markdown table (--pr-comment).
//
// Usage:
//   node scripts/coverage-summary.mjs              # prints shields.io URL
//   node scripts/coverage-summary.mjs --pr-comment # prints markdown for PR
//   node scripts/coverage-summary.mjs --json       # prints raw totals

import fs from "node:fs";
import path from "node:path";
import { fileURLToPath, pathToFileURL } from "node:url";

const MARKER = "<!-- coverage-report -->";
const repoRoot = path.resolve(fileURLToPath(import.meta.url), "..", "..");
const targetsPath = path.join(repoRoot, "scripts", "coverage-targets.json");

export function resolveSummaryPath({ root = repoRoot, env = process.env, fsApi = fs } = {}) {
  if (env.COVERAGE_SUMMARY_PATH) {
    return path.resolve(root, env.COVERAGE_SUMMARY_PATH);
  }

  const candidates = [
    path.join(root, "coverage-gate", "coverage-summary.json"),
    path.join(root, "coverage", "coverage-summary.json"),
  ];

  return candidates.find((candidate) => fsApi.existsSync(candidate)) ?? candidates[0];
}

function loadSummary() {
  const summaryPath = resolveSummaryPath();
  if (!fs.existsSync(summaryPath)) return null;
  return JSON.parse(fs.readFileSync(summaryPath, "utf8"));
}

function loadTargets() {
  if (!fs.existsSync(targetsPath)) return [];
  return JSON.parse(fs.readFileSync(targetsPath, "utf8"));
}

function aggregateTotals(summary) {
  const total = summary.total ?? null;
  if (!total) return null;
  return {
    statements: total.statements?.pct ?? 0,
    branches: total.branches?.pct ?? 0,
    functions: total.functions?.pct ?? 0,
    lines: total.lines?.pct ?? 0,
  };
}

function pickColor(pct) {
  if (pct >= 90) return "brightgreen";
  if (pct >= 75) return "green";
  if (pct >= 60) return "yellowgreen";
  if (pct >= 50) return "yellow";
  if (pct >= 40) return "orange";
  return "red";
}

function shieldsUrl(totals) {
  if (!totals) return "https://img.shields.io/badge/coverage-unknown-lightgrey";
  const pct = totals.statements.toFixed(1);
  return `https://img.shields.io/badge/coverage-${pct}%25-${pickColor(totals.statements)}`;
}

function evaluatePerPath(summary, targets) {
  const rows = [];
  for (const target of targets) {
    const filtered = Object.entries(summary).filter(([file]) => {
      if (file === "total") return false;
      const rel = path.relative(repoRoot, file);
      return target.pathPrefixes.some((prefix) => rel.startsWith(prefix));
    });
    if (filtered.length === 0) {
      rows.push({ name: target.name, statementsPct: null, branchesPct: null, target, status: "skip" });
      continue;
    }
    const totals = filtered.reduce(
      (acc, [, m]) => ({
        statements: acc.statements + m.statements.covered,
        statementsTotal: acc.statementsTotal + m.statements.total,
        branches: acc.branches + m.branches.covered,
        branchesTotal: acc.branchesTotal + m.branches.total,
      }),
      { statements: 0, statementsTotal: 0, branches: 0, branchesTotal: 0 }
    );
    const statementsPct = totals.statementsTotal > 0 ? (totals.statements / totals.statementsTotal) * 100 : 0;
    const branchesPct = totals.branchesTotal > 0 ? (totals.branches / totals.branchesTotal) * 100 : 0;
    const passes = statementsPct >= target.statements && branchesPct >= target.branches;
    rows.push({
      name: target.name,
      statementsPct,
      branchesPct,
      target,
      status: passes ? "pass" : "fail",
    });
  }
  return rows;
}

function renderPrComment(totals, rows) {
  const lines = [];
  lines.push(MARKER);
  lines.push("## Coverage Report");
  lines.push("");
  if (!totals) {
    lines.push("_coverage-summary.json not found — vitest with --coverage did not run._");
    return lines.join("\n");
  }
  lines.push("| metric | total |");
  lines.push("|---|---|");
  lines.push(`| statements | **${totals.statements.toFixed(1)}%** |`);
  lines.push(`| branches | **${totals.branches.toFixed(1)}%** |`);
  lines.push(`| functions | **${totals.functions.toFixed(1)}%** |`);
  lines.push(`| lines | **${totals.lines.toFixed(1)}%** |`);
  lines.push("");
  lines.push("### Per-path thresholds");
  lines.push("");
  lines.push("| path | statements | branches | gate | status |");
  lines.push("|---|---|---|---|---|");
  for (const row of rows) {
    const tag = row.target.criticalPath ? " (critical)" : "";
    const statements = row.statementsPct === null ? "n/a" : `${row.statementsPct.toFixed(1)}%`;
    const branches = row.branchesPct === null ? "n/a" : `${row.branchesPct.toFixed(1)}%`;
    const gate = `${row.target.statements}% / ${row.target.branches}%`;
    const icon = row.status === "pass" ? "PASS" : row.status === "fail" ? "FAIL" : "SKIP";
    lines.push(`| ${row.name}${tag} | ${statements} | ${branches} | ${gate} | ${icon} |`);
  }
  lines.push("");
  lines.push("_Bump thresholds by editing `scripts/coverage-targets.json`. See `docs/architecture/test-coverage.md`._");
  return lines.join("\n");
}

export function main() {
  const argv = process.argv.slice(2);
  const summary = loadSummary();
  const targets = loadTargets();
  const totals = summary ? aggregateTotals(summary) : null;

  if (argv.includes("--pr-comment")) {
    const rows = summary ? evaluatePerPath(summary, targets) : [];
    process.stdout.write(renderPrComment(totals, rows) + "\n");
    return;
  }
  if (argv.includes("--json")) {
    process.stdout.write(JSON.stringify(totals ?? {}, null, 2) + "\n");
    return;
  }
  // Default: shields.io badge URL
  process.stdout.write(shieldsUrl(totals) + "\n");
}

if (process.argv[1] && import.meta.url === pathToFileURL(process.argv[1]).href) {
  main();
}