#!/usr/bin/env node

import { execFileSync } from "node:child_process";
import fs from "node:fs";
import path from "node:path";
import { fileURLToPath } from "node:url";

const SCRIPT_DIR = path.dirname(fileURLToPath(import.meta.url));
const REPO_ROOT = path.resolve(SCRIPT_DIR, "../..");

export const COMMIT_HISTORY_DAYS = 60;
export const COMMIT_HISTORY_TIME_ZONE = "Europe/Berlin";

const DEFAULTS = Object.freeze({
  days: COMMIT_HISTORY_DAYS,
  label: null,
  outputDir: "docs/metrics",
  ref: "origin/main",
});

function printHelp() {
  console.log(`Usage: node scripts/metrics/commit-history.mjs [options]

Options:
  --ref <git-ref>        Revision to inspect (default: ${DEFAULTS.ref})
  --label <text>         Ref label rendered in outputs (default: value of --ref)
  --days <number>        Calendar days to render (default: ${DEFAULTS.days})
  --output-dir <path>    Output directory (default: ${DEFAULTS.outputDir})
  --help                 Show this help

Outputs:
  commit-history.csv     Daily commit counts
  commit-history.svg     Standalone 60-day chart

All commits reachable from the selected revision are counted by committer date,
including merge commits and commits introduced by merged branches. Calendar days
are grouped in ${COMMIT_HISTORY_TIME_ZONE}; days without commits remain visible.`);
}

export function parseArgs(argv) {
  const options = { ...DEFAULTS };

  for (let index = 0; index < argv.length; index += 1) {
    const argument = argv[index];
    if (argument === "--help") {
      printHelp();
      process.exit(0);
    }
    if (argument === "--ref" || argument === "--label" || argument === "--days" || argument === "--output-dir") {
      const value = argv[index + 1];
      if (!value || value.startsWith("--")) throw new Error(`Missing value for ${argument}`);
      if (argument === "--ref") options.ref = value;
      if (argument === "--label") options.label = value;
      if (argument === "--output-dir") options.outputDir = value;
      if (argument === "--days") {
        const days = Number(value);
        if (!Number.isInteger(days) || days < 1 || days > 365) {
          throw new Error("--days must be an integer between 1 and 365");
        }
        options.days = days;
      }
      index += 1;
      continue;
    }
    throw new Error(`Unknown argument: ${argument}`);
  }

  return { ...options, label: options.label ?? options.ref };
}

function git(args, options = {}) {
  return execFileSync("git", args, {
    cwd: options.repoRoot ?? REPO_ROOT,
    encoding: "utf8",
    maxBuffer: 64 * 1024 * 1024,
  });
}

export function toBerlinDateKey(timestamp) {
  const date = new Date(timestamp);
  if (Number.isNaN(date.getTime())) throw new Error(`Invalid Git timestamp: ${timestamp}`);

  const parts = new Intl.DateTimeFormat("en-US", {
    day: "2-digit",
    month: "2-digit",
    timeZone: COMMIT_HISTORY_TIME_ZONE,
    year: "numeric",
  }).formatToParts(date);
  const value = (type) => parts.find((part) => part.type === type)?.value;
  return `${value("year")}-${value("month")}-${value("day")}`;
}

function addCalendarDays(dateKey, amount) {
  const [year, month, day] = dateKey.split("-").map(Number);
  const date = new Date(Date.UTC(year, month - 1, day + amount, 12));
  return date.toISOString().slice(0, 10);
}

export function collectCommitHistory(ref, { days = COMMIT_HISTORY_DAYS, repoRoot = REPO_ROOT, runGit = git } = {}) {
  const resolvedRef = runGit(["rev-parse", "--verify", `${ref}^{commit}`], { repoRoot }).trim();
  const tipTimestamp = runGit(["show", "-s", "--format=%cI", resolvedRef], { repoRoot }).trim();
  const endDate = toBerlinDateKey(tipTimestamp);
  const startDate = addCalendarDays(endDate, -(days - 1));
  const rows = [];
  const counts = new Map();

  for (let offset = 0; offset < days; offset += 1) {
    const date = addCalendarDays(startDate, offset);
    const row = { count: 0, date };
    rows.push(row);
    counts.set(date, row);
  }

  const log = runGit(["log", resolvedRef, "--format=%H%x09%cI"], { repoRoot }).trim();
  if (log) {
    for (const line of log.split("\n")) {
      const [sha, timestamp] = line.split("\t");
      if (!sha || !timestamp) throw new Error(`Malformed Git log entry: ${line}`);
      const row = counts.get(toBerlinDateKey(timestamp));
      if (row) row.count += 1;
    }
  }

  return { days, endDate, resolvedRef, rows, startDate, tipTimestamp };
}

function escapeXml(value) {
  return String(value).replaceAll("&", "&amp;").replaceAll("<", "&lt;").replaceAll(">", "&gt;").replaceAll('"', "&quot;").replaceAll("'", "&apos;");
}

function formatNumber(value) {
  return new Intl.NumberFormat("de-DE").format(Math.round(value));
}

function formatDecimal(value) {
  return new Intl.NumberFormat("de-DE", {
    maximumFractionDigits: 1,
    minimumFractionDigits: 1,
  }).format(value);
}

function formatDisplayDate(dateKey) {
  const [, month, day] = dateKey.split("-");
  return `${day}.${month}.`;
}

function niceAxisMaximum(value) {
  if (value <= 0) return 1;
  const roughStep = value / 4;
  const magnitude = 10 ** Math.floor(Math.log10(roughStep));
  const normalized = roughStep / magnitude;
  const niceNormalized = normalized <= 1 ? 1 : normalized <= 2 ? 2 : normalized <= 2.5 ? 2.5 : normalized <= 4 ? 4 : normalized <= 5 ? 5 : 10;
  const step = niceNormalized * magnitude;
  return Math.ceil(value / step) * step;
}

export function renderCsv(history, ref) {
  const metadata = [
    `# ref=${ref}`,
    `# resolved_tip=${history.resolvedRef}`,
    `# tip_timestamp=${history.tipTimestamp}`,
    "# metric=commits reachable from ref grouped by committer date",
    `# window_days=${history.days}`,
    `# timezone=${COMMIT_HISTORY_TIME_ZONE}`,
    "# included=merge commits and commits introduced by merged branches",
    "# excluded=commits reachable only from other branches such as loc-metrics",
  ];
  const body = history.rows.map((row) => `${row.date},${row.count}`);
  return `${[...metadata, "date,commit_count", ...body].join("\n")}\n`;
}

export function renderSvg(history, ref) {
  const width = 1600;
  const height = 900;
  const plot = { bottom: 730, left: 126, right: 1518, top: 320 };
  const plotWidth = plot.right - plot.left;
  const plotHeight = plot.bottom - plot.top;
  const rows = history.rows;
  if (rows.length === 0) throw new Error("Commit history requires at least one calendar day");

  const latest = rows.at(-1);
  const latestIndex = rows.length - 1;
  const lastSeven = rows.slice(-7).reduce((sum, row) => sum + row.count, 0);
  const total = rows.reduce((sum, row) => sum + row.count, 0);
  const average = total / rows.length;
  const peakCount = Math.max(...rows.map((row) => row.count));
  const peakIndex = rows.findIndex((row) => row.count === peakCount);
  const peak = rows[peakIndex];
  const axisMaximum = niceAxisMaximum(peakCount * 1.02);
  const step = plotWidth / rows.length;
  const barWidth = Math.max(4, Math.min(28, step * 0.6));
  const x = (index) => plot.left + (index + 0.5) * step;
  const y = (value) => plot.bottom - (value / axisMaximum) * plotHeight;
  const barHeight = (value) => (value / axisMaximum) * plotHeight;
  const trendPoints = [];
  for (let index = 6; index < rows.length; index += 1) {
    const movingAverage = rows.slice(index - 6, index + 1).reduce((sum, row) => sum + row.count, 0) / 7;
    trendPoints.push(`${x(index).toFixed(1)},${y(movingAverage).toFixed(1)}`);
  }

  const cards = [
    { color: "#0F172A", label: "HEUTE", value: `${formatNumber(latest.count)} Commits` },
    { color: "#0F766E", label: "LETZTE 7 TAGE", value: `${formatNumber(lastSeven)} Commits` },
    { color: "#F59E0B", label: `Ø PRO TAG · ${history.days} TAGE`, value: `${formatDecimal(average)} Commits` },
    { color: "#8B5CF6", label: `PEAK · ${formatDisplayDate(peak.date)}`, value: `${formatNumber(peak.count)} Commits` },
  ];

  const svg = [];
  svg.push(`<?xml version="1.0" encoding="UTF-8"?>`);
  svg.push(
    `<svg xmlns="http://www.w3.org/2000/svg" width="${width}" height="${height}" viewBox="0 0 ${width} ${height}" role="img" aria-labelledby="title description">`
  );
  svg.push(`<title id="title">HiveGrid Commit-Aktivität auf ${escapeXml(ref)}</title>`);
  svg.push(
    `<desc id="description">Tägliche Anzahl aller von ${escapeXml(ref)} erreichbaren Commits für die letzten ${history.days} Kalendertage, gruppiert in der Zeitzone ${COMMIT_HISTORY_TIME_ZONE}, mit Sieben-Tage-Durchschnitt.</desc>`
  );
  svg.push(
    `<style>.text{font-family:Inter,ui-sans-serif,system-ui,sans-serif}.grid{stroke:#E2E8F0;stroke-width:1}.axis-label{fill:#64748B;font-size:15px}.bar{fill:#0F766E;fill-opacity:.82}</style>`
  );
  svg.push(`<rect width="${width}" height="${height}" fill="#F8FAFC"/>`);
  svg.push(`<text class="text" x="78" y="74" fill="#0F172A" font-size="36" font-weight="750">HiveGrid · Commit-Aktivität</text>`);
  svg.push(
    `<text class="text" x="78" y="110" fill="#64748B" font-size="18">${escapeXml(ref)} @ ${history.resolvedRef.slice(0, 9)} · letzte ${history.days} Kalendertage · ${COMMIT_HISTORY_TIME_ZONE} · heute laufend</text>`
  );

  cards.forEach((card, index) => {
    const cardX = 78 + index * 366;
    svg.push(`<rect x="${cardX}" y="142" width="340" height="92" rx="14" fill="#FFFFFF" stroke="#E2E8F0"/>`);
    svg.push(`<rect x="${cardX}" y="142" width="6" height="92" rx="3" fill="${card.color}"/>`);
    svg.push(
      `<text class="text" x="${cardX + 26}" y="174" fill="#64748B" font-size="14" font-weight="650" letter-spacing="0.5">${escapeXml(card.label)}</text>`
    );
    svg.push(`<text class="text" x="${cardX + 26}" y="211" fill="#0F172A" font-size="29" font-weight="750">${escapeXml(card.value)}</text>`);
  });

  for (let tick = 0; tick <= 4; tick += 1) {
    const value = (axisMaximum / 4) * tick;
    const tickY = y(value);
    svg.push(`<line class="grid" x1="${plot.left}" y1="${tickY}" x2="${plot.right}" y2="${tickY}"${tick === 0 ? ' stroke="#CBD5E1"' : ""}/>`);
    svg.push(`<text class="text axis-label" x="${plot.left - 18}" y="${tickY + 6}" text-anchor="end">${escapeXml(formatNumber(value))}</text>`);
  }

  rows.forEach((row, index) => {
    const isLatest = index === latestIndex;
    const isPeak = index === peakIndex && !isLatest;
    const fill = isLatest ? "#0F172A" : isPeak ? "#8B5CF6" : null;
    const extra = fill ? ` fill="${fill}"${isPeak ? ' fill-opacity="0.9"' : ""}` : ' class="bar"';
    svg.push(
      `<rect${extra} x="${(x(index) - barWidth / 2).toFixed(1)}" y="${y(row.count).toFixed(1)}" width="${barWidth.toFixed(1)}" height="${barHeight(row.count).toFixed(1)}" rx="${Math.min(4, barWidth / 2).toFixed(1)}"/>`
    );
  });

  if (trendPoints.length > 0) {
    svg.push(`<polyline points="${trendPoints.join(" ")}" fill="none" stroke="#F59E0B" stroke-width="4" stroke-linecap="round" stroke-linejoin="round"/>`);
    const lastTrendPoint = trendPoints.at(-1).split(",");
    svg.push(`<circle cx="${lastTrendPoint[0]}" cy="${lastTrendPoint[1]}" r="6" fill="#F59E0B" stroke="#FFFFFF" stroke-width="3"/>`);
  }

  const renderValueLabel = (index, value, color, stroke) => {
    const centerX = x(index);
    const labelY = Math.max(plot.top - 22, y(value) - 45);
    svg.push(`<rect x="${(centerX - 27).toFixed(1)}" y="${labelY.toFixed(1)}" width="54" height="30" rx="10" fill="#FFFFFF" stroke="${stroke}"/>`);
    svg.push(
      `<text class="text" x="${centerX.toFixed(1)}" y="${(labelY + 20).toFixed(1)}" fill="${color}" font-size="14" font-weight="750" text-anchor="middle">${escapeXml(formatNumber(value))}</text>`
    );
  };
  if (peakIndex !== latestIndex && Math.abs(x(peakIndex) - x(latestIndex)) >= 60) {
    renderValueLabel(peakIndex, peak.count, "#7C3AED", "#DDD6FE");
  }
  renderValueLabel(latestIndex, latest.count, "#0F172A", "#CBD5E1");

  const tickCount = Math.min(7, rows.length);
  const tickIndexes = new Set();
  for (let tick = 0; tick < tickCount; tick += 1) {
    const index = tick === tickCount - 1 ? rows.length - 1 : Math.round((tick * rows.length) / Math.max(1, tickCount - 1));
    tickIndexes.add(Math.min(rows.length - 1, index));
  }
  for (const index of tickIndexes) {
    const tickX = x(index);
    svg.push(`<line x1="${tickX.toFixed(1)}" y1="${plot.bottom}" x2="${tickX.toFixed(1)}" y2="${plot.bottom + 8}" stroke="#94A3B8"/>`);
    svg.push(
      `<text class="text axis-label" x="${tickX.toFixed(1)}" y="${plot.bottom + 34}" text-anchor="middle">${formatDisplayDate(rows[index].date)}</text>`
    );
  }

  svg.push(`<rect x="126" y="814" width="16" height="16" rx="4" fill="#0F766E" fill-opacity="0.82"/>`);
  svg.push(`<text class="text" x="151" y="828" fill="#475569" font-size="15">Commits pro Tag</text>`);
  svg.push(`<line x1="322" y1="822" x2="350" y2="822" stroke="#F59E0B" stroke-width="4" stroke-linecap="round"/>`);
  svg.push(`<text class="text" x="362" y="828" fill="#475569" font-size="15">7-Tage-Durchschnitt</text>`);
  svg.push(
    `<text class="text" x="1518" y="828" text-anchor="end" fill="#94A3B8" font-size="13">Alle von main erreichbaren Commits · Merge-Commits und Branch-Commits · Tage ohne Commits = 0</text>`
  );
  svg.push(`</svg>`);
  return `${svg.join("\n")}\n`;
}

function main() {
  const options = parseArgs(process.argv.slice(2));
  const outputDir = path.resolve(REPO_ROOT, options.outputDir);
  const history = collectCommitHistory(options.ref, { days: options.days, repoRoot: REPO_ROOT });

  fs.mkdirSync(outputDir, { recursive: true });
  fs.writeFileSync(path.join(outputDir, "commit-history.csv"), renderCsv(history, options.label));
  fs.writeFileSync(path.join(outputDir, "commit-history.svg"), renderSvg(history, options.label));

  const latest = history.rows.at(-1);
  const total = history.rows.reduce((sum, row) => sum + row.count, 0);
  console.log(`Commit history: ${history.days} calendar days from ${history.startDate} to ${history.endDate}`);
  console.log(`Latest day: ${formatNumber(latest.count)} commits; window total: ${formatNumber(total)}`);
  console.log(`Wrote ${path.relative(REPO_ROOT, outputDir)}/commit-history.{csv,svg}`);
}

const invokedDirectly = process.argv[1] && path.resolve(process.argv[1]) === fileURLToPath(import.meta.url);
if (invokedDirectly) {
  try {
    main();
  } catch (error) {
    console.error(error instanceof Error ? error.message : error);
    process.exit(1);
  }
}