import { readFileSync, writeFileSync } from "node:fs";
import path from "node:path";

const IOS_VERSION_FILE = "apps/ios/version.json";
const IOS_CHANGELOG_FILE = "apps/ios/CHANGELOG.md";
const IOS_VERSION_XCCONFIG_FILE = "apps/ios/Config/Version.xcconfig";
const IOS_RELEASE_NOTES_FILE = "apps/ios/fastlane/metadata/en-US/release_notes.txt";

const PINNED_IOS_VERSION_PATTERN = /^(\d{4}\.\d{1,2}\.\d{1,2})$/u;
const GATEWAY_VERSION_PATTERN = /^(\d{4}\.\d{1,2}\.\d{1,2})(?:-(?:alpha\.\d+|beta\.\d+|\d+))?$/u;

type IosVersionManifest = {
  version: string;
};

type ResolvedIosVersion = {
  canonicalVersion: string;
  marketingVersion: string;
  buildVersion: string;
  versionFilePath: string;
  changelogPath: string;
  versionXcconfigPath: string;
  releaseNotesPath: string;
};

type SyncIosVersioningMode = "check" | "write";

function normalizeTrailingNewline(value: string): string {
  return value.endsWith("\n") ? value : `${value}\n`;
}

export function normalizePinnedIosVersion(rawVersion: string): string {
  const trimmed = rawVersion.trim();
  if (!trimmed) {
    throw new Error(`Missing iOS version in ${IOS_VERSION_FILE}.`);
  }

  const match = PINNED_IOS_VERSION_PATTERN.exec(trimmed);
  if (!match) {
    throw new Error(`Invalid iOS version '${rawVersion}'. Expected pinned CalVer like 2026.4.6.`);
  }

  return match[1] ?? trimmed;
}

export function normalizeGatewayVersionToPinnedIosVersion(rawVersion: string): string {
  const trimmed = rawVersion.trim().replace(/^v/u, "");
  if (!trimmed) {
    throw new Error("Missing root package.json version.");
  }

  const match = GATEWAY_VERSION_PATTERN.exec(trimmed);
  if (!match) {
    throw new Error(
      `Invalid gateway version '${rawVersion}'. Expected YYYY.M.D, YYYY.M.D-alpha.N, YYYY.M.D-beta.N, or YYYY.M.D-N.`,
    );
  }

  return match[1] ?? trimmed;
}

function readRootPackageVersion(rootDir = path.resolve(".")): string {
  const packageJsonPath = path.join(rootDir, "package.json");
  const parsed = JSON.parse(readFileSync(packageJsonPath, "utf8")) as { version?: unknown };
  const version = typeof parsed.version === "string" ? parsed.version.trim() : "";
  if (!version) {
    throw new Error(`Missing package.json version in ${packageJsonPath}.`);
  }
  return version;
}

export function resolveGatewayVersionForIosRelease(rootDir = path.resolve(".")): {
  packageVersion: string;
  pinnedIosVersion: string;
} {
  const packageVersion = readRootPackageVersion(rootDir);
  return {
    packageVersion,
    pinnedIosVersion: normalizeGatewayVersionToPinnedIosVersion(packageVersion),
  };
}

function readIosVersionManifest(rootDir = path.resolve(".")): IosVersionManifest {
  const versionFilePath = path.join(rootDir, IOS_VERSION_FILE);
  return JSON.parse(readFileSync(versionFilePath, "utf8")) as IosVersionManifest;
}

export function writeIosVersionManifest(version: string, rootDir = path.resolve(".")): string {
  const versionFilePath = path.join(rootDir, IOS_VERSION_FILE);
  const normalizedVersion = normalizePinnedIosVersion(version);
  const nextContent = `${JSON.stringify({ version: normalizedVersion }, null, 2)}\n`;
  writeFileSync(versionFilePath, nextContent, "utf8");
  return versionFilePath;
}

export function resolveIosVersion(rootDir = path.resolve(".")): ResolvedIosVersion {
  const versionFilePath = path.join(rootDir, IOS_VERSION_FILE);
  const changelogPath = path.join(rootDir, IOS_CHANGELOG_FILE);
  const versionXcconfigPath = path.join(rootDir, IOS_VERSION_XCCONFIG_FILE);
  const releaseNotesPath = path.join(rootDir, IOS_RELEASE_NOTES_FILE);
  const manifest = readIosVersionManifest(rootDir);
  const canonicalVersion = normalizePinnedIosVersion(manifest.version ?? "");

  return {
    canonicalVersion,
    marketingVersion: canonicalVersion,
    buildVersion: "1",
    versionFilePath,
    changelogPath,
    versionXcconfigPath,
    releaseNotesPath,
  };
}

export function renderIosVersionXcconfig(version: ResolvedIosVersion): string {
  return `// Shared iOS version defaults.\n// Source of truth: apps/ios/version.json\n// Generated by scripts/ios-sync-versioning.ts.\n\nOPENCLAW_IOS_VERSION = ${version.canonicalVersion}\nOPENCLAW_MARKETING_VERSION = ${version.marketingVersion}\nOPENCLAW_BUILD_VERSION = ${version.buildVersion}\n\n#include? "../build/Version.xcconfig"\n`;
}

function matchChangelogHeading(line: string, heading: string): boolean {
  const normalized = line.trim();
  return normalized === `## ${heading}` || normalized.startsWith(`## ${heading} - `);
}

export function extractChangelogSection(content: string, heading: string): string | null {
  const lines = content.split(/\r?\n/);
  const startIndex = lines.findIndex((line) => matchChangelogHeading(line, heading));
  if (startIndex === -1) {
    return null;
  }

  let endIndex = lines.length;
  for (let index = startIndex + 1; index < lines.length; index += 1) {
    if (lines[index]?.startsWith("## ")) {
      endIndex = index;
      break;
    }
  }

  const body = lines
    .slice(startIndex + 1, endIndex)
    .join("\n")
    .trim();
  return body || null;
}

export function renderIosReleaseNotes(
  version: ResolvedIosVersion,
  changelogContent: string,
): string {
  const candidateHeadings = [version.canonicalVersion, "Unreleased"];

  for (const heading of candidateHeadings) {
    const body = extractChangelogSection(changelogContent, heading);
    if (body) {
      return `${body}\n`;
    }
  }

  throw new Error(
    `Unable to find iOS changelog notes for ${version.canonicalVersion}. Add a matching section to ${IOS_CHANGELOG_FILE}.`,
  );
}

function syncFile(params: {
  mode: SyncIosVersioningMode;
  path: string;
  nextContent: string;
  label: string;
}): boolean {
  const nextContent = normalizeTrailingNewline(params.nextContent);
  const currentContent = readFileSync(params.path, "utf8");
  if (currentContent === nextContent) {
    return false;
  }

  if (params.mode === "check") {
    throw new Error(`${params.label} is stale: ${path.relative(process.cwd(), params.path)}`);
  }

  writeFileSync(params.path, nextContent, "utf8");
  return true;
}

export function syncIosVersioning(params?: { mode?: SyncIosVersioningMode; rootDir?: string }): {
  updatedPaths: string[];
} {
  const mode = params?.mode ?? "write";
  const rootDir = path.resolve(params?.rootDir ?? ".");
  const version = resolveIosVersion(rootDir);
  const changelogContent = readFileSync(version.changelogPath, "utf8");
  const nextVersionXcconfig = renderIosVersionXcconfig(version);
  const nextReleaseNotes = renderIosReleaseNotes(version, changelogContent);
  const updatedPaths: string[] = [];

  if (
    syncFile({
      mode,
      path: version.versionXcconfigPath,
      nextContent: nextVersionXcconfig,
      label: "iOS version xcconfig",
    })
  ) {
    updatedPaths.push(version.versionXcconfigPath);
  }

  if (
    syncFile({
      mode,
      path: version.releaseNotesPath,
      nextContent: nextReleaseNotes,
      label: "iOS release notes",
    })
  ) {
    updatedPaths.push(version.releaseNotesPath);
  }

  return { updatedPaths };
}
