import { spawn, type ChildProcess } from "node:child_process";
import { constants as fsConstants, promises as fs } from "node:fs";
import path from "node:path";

export interface RunProcessResult {
  exitCode: number | null;
  signal: string | null;
  timedOut: boolean;
  stdout: string;
  stderr: string;
}

interface RunningProcess {
  child: ChildProcess;
  graceSec: number;
}

interface SpawnTarget {
  command: string;
  args: string[];
}

type ChildProcessWithEvents = ChildProcess & {
  on(event: "error", listener: (err: Error) => void): ChildProcess;
  on(
    event: "close",
    listener: (code: number | null, signal: NodeJS.Signals | null) => void,
  ): ChildProcess;
};

export const runningProcesses = new Map<string, RunningProcess>();
export const MAX_CAPTURE_BYTES = 4 * 1024 * 1024;
export const MAX_EXCERPT_BYTES = 32 * 1024;
const SENSITIVE_ENV_KEY = /(key|token|secret|password|passwd|authorization|cookie)/i;
const PAPERCLIP_SKILL_ROOT_RELATIVE_CANDIDATES = [
  "../../skills",
  "../../../../../skills",
];

export interface PaperclipSkillEntry {
  name: string;
  source: string;
}

function normalizePathSlashes(value: string): string {
  return value.replaceAll("\\", "/");
}

function isMaintainerOnlySkillTarget(candidate: string): boolean {
  return normalizePathSlashes(candidate).includes("/.agents/skills/");
}

export function parseObject(value: unknown): Record<string, unknown> {
  if (typeof value !== "object" || value === null || Array.isArray(value)) {
    return {};
  }
  return value as Record<string, unknown>;
}

export function asString(value: unknown, fallback: string): string {
  return typeof value === "string" && value.length > 0 ? value : fallback;
}

export function asNumber(value: unknown, fallback: number): number {
  return typeof value === "number" && Number.isFinite(value) ? value : fallback;
}

export function asBoolean(value: unknown, fallback: boolean): boolean {
  return typeof value === "boolean" ? value : fallback;
}

export function asStringArray(value: unknown): string[] {
  return Array.isArray(value) ? value.filter((item): item is string => typeof item === "string") : [];
}

export function parseJson(value: string): Record<string, unknown> | null {
  try {
    return JSON.parse(value) as Record<string, unknown>;
  } catch {
    return null;
  }
}

export function appendWithCap(prev: string, chunk: string, cap = MAX_CAPTURE_BYTES) {
  const combined = prev + chunk;
  return combined.length > cap ? combined.slice(combined.length - cap) : combined;
}

export function resolvePathValue(obj: Record<string, unknown>, dottedPath: string) {
  const parts = dottedPath.split(".");
  let cursor: unknown = obj;

  for (const part of parts) {
    if (typeof cursor !== "object" || cursor === null || Array.isArray(cursor)) {
      return "";
    }
    cursor = (cursor as Record<string, unknown>)[part];
  }

  if (cursor === null || cursor === undefined) return "";
  if (typeof cursor === "string") return cursor;
  if (typeof cursor === "number" || typeof cursor === "boolean") return String(cursor);

  try {
    return JSON.stringify(cursor);
  } catch {
    return "";
  }
}

export function renderTemplate(template: string, data: Record<string, unknown>) {
  return template.replace(/{{\s*([a-zA-Z0-9_.-]+)\s*}}/g, (_, path) => resolvePathValue(data, path));
}

export function joinPromptSections(
  sections: Array<string | null | undefined>,
  separator = "\n\n",
) {
  return sections
    .map((value) => (typeof value === "string" ? value.trim() : ""))
    .filter(Boolean)
    .join(separator);
}

export function redactEnvForLogs(env: Record<string, string>): Record<string, string> {
  const redacted: Record<string, string> = {};
  for (const [key, value] of Object.entries(env)) {
    redacted[key] = SENSITIVE_ENV_KEY.test(key) ? "***REDACTED***" : value;
  }
  return redacted;
}

export function buildPaperclipEnv(agent: { id: string; companyId: string }): Record<string, string> {
  const resolveHostForUrl = (rawHost: string): string => {
    const host = rawHost.trim();
    if (!host || host === "0.0.0.0" || host === "::") return "localhost";
    if (host.includes(":") && !host.startsWith("[") && !host.endsWith("]")) return `[${host}]`;
    return host;
  };
  const vars: Record<string, string> = {
    PAPERCLIP_AGENT_ID: agent.id,
    PAPERCLIP_COMPANY_ID: agent.companyId,
  };
  const runtimeHost = resolveHostForUrl(
    process.env.PAPERCLIP_LISTEN_HOST ?? process.env.HOST ?? "localhost",
  );
  const runtimePort = process.env.PAPERCLIP_LISTEN_PORT ?? process.env.PORT ?? "3100";
  const apiUrl = process.env.PAPERCLIP_API_URL ?? `http://${runtimeHost}:${runtimePort}`;
  vars.PAPERCLIP_API_URL = apiUrl;
  return vars;
}

export function defaultPathForPlatform() {
  if (process.platform === "win32") {
    return "C:\\Windows\\System32;C:\\Windows;C:\\Windows\\System32\\Wbem";
  }
  return "/usr/local/bin:/opt/homebrew/bin:/usr/local/sbin:/usr/bin:/bin:/usr/sbin:/sbin";
}

function windowsPathExts(env: NodeJS.ProcessEnv): string[] {
  return (env.PATHEXT ?? ".EXE;.CMD;.BAT;.COM").split(";").filter(Boolean);
}

async function pathExists(candidate: string) {
  try {
    await fs.access(candidate, process.platform === "win32" ? fsConstants.F_OK : fsConstants.X_OK);
    return true;
  } catch {
    return false;
  }
}

async function resolveCommandPath(command: string, cwd: string, env: NodeJS.ProcessEnv): Promise<string | null> {
  const hasPathSeparator = command.includes("/") || command.includes("\\");
  if (hasPathSeparator) {
    const absolute = path.isAbsolute(command) ? command : path.resolve(cwd, command);
    return (await pathExists(absolute)) ? absolute : null;
  }

  const pathValue = env.PATH ?? env.Path ?? "";
  const delimiter = process.platform === "win32" ? ";" : ":";
  const dirs = pathValue.split(delimiter).filter(Boolean);
  const exts = process.platform === "win32" ? windowsPathExts(env) : [""];
  const hasExtension = process.platform === "win32" && path.extname(command).length > 0;

  for (const dir of dirs) {
    const candidates =
      process.platform === "win32"
        ? hasExtension
          ? [path.join(dir, command)]
          : exts.map((ext) => path.join(dir, `${command}${ext}`))
        : [path.join(dir, command)];
    for (const candidate of candidates) {
      if (await pathExists(candidate)) return candidate;
    }
  }

  return null;
}

function quoteForCmd(arg: string) {
  if (!arg.length) return '""';
  const escaped = arg.replace(/"/g, '""');
  return /[\s"&<>|^()]/.test(escaped) ? `"${escaped}"` : escaped;
}

async function resolveSpawnTarget(
  command: string,
  args: string[],
  cwd: string,
  env: NodeJS.ProcessEnv,
): Promise<SpawnTarget> {
  const resolved = await resolveCommandPath(command, cwd, env);
  const executable = resolved ?? command;

  if (process.platform !== "win32") {
    return { command: executable, args };
  }

  if (/\.(cmd|bat)$/i.test(executable)) {
    const shell = env.ComSpec || process.env.ComSpec || "cmd.exe";
    const commandLine = [quoteForCmd(executable), ...args.map(quoteForCmd)].join(" ");
    return {
      command: shell,
      args: ["/d", "/s", "/c", commandLine],
    };
  }

  return { command: executable, args };
}

export function ensurePathInEnv(env: NodeJS.ProcessEnv): NodeJS.ProcessEnv {
  if (typeof env.PATH === "string" && env.PATH.length > 0) return env;
  if (typeof env.Path === "string" && env.Path.length > 0) return env;
  return { ...env, PATH: defaultPathForPlatform() };
}

export async function ensureAbsoluteDirectory(
  cwd: string,
  opts: { createIfMissing?: boolean } = {},
) {
  if (!path.isAbsolute(cwd)) {
    throw new Error(`Working directory must be an absolute path: "${cwd}"`);
  }

  const assertDirectory = async () => {
    const stats = await fs.stat(cwd);
    if (!stats.isDirectory()) {
      throw new Error(`Working directory is not a directory: "${cwd}"`);
    }
  };

  try {
    await assertDirectory();
    return;
  } catch (err) {
    const code = (err as NodeJS.ErrnoException).code;
    if (!opts.createIfMissing || code !== "ENOENT") {
      if (code === "ENOENT") {
        throw new Error(`Working directory does not exist: "${cwd}"`);
      }
      throw err instanceof Error ? err : new Error(String(err));
    }
  }

  try {
    await fs.mkdir(cwd, { recursive: true });
    await assertDirectory();
  } catch (err) {
    const reason = err instanceof Error ? err.message : String(err);
    throw new Error(`Could not create working directory "${cwd}": ${reason}`);
  }
}

export async function resolvePaperclipSkillsDir(
  moduleDir: string,
  additionalCandidates: string[] = [],
): Promise<string | null> {
  const candidates = [
    ...PAPERCLIP_SKILL_ROOT_RELATIVE_CANDIDATES.map((relativePath) => path.resolve(moduleDir, relativePath)),
    ...additionalCandidates.map((candidate) => path.resolve(candidate)),
  ];
  const seenRoots = new Set<string>();

  for (const root of candidates) {
    if (seenRoots.has(root)) continue;
    seenRoots.add(root);
    const isDirectory = await fs.stat(root).then((stats) => stats.isDirectory()).catch(() => false);
    if (isDirectory) return root;
  }

  return null;
}

export async function listPaperclipSkillEntries(
  moduleDir: string,
  additionalCandidates: string[] = [],
): Promise<PaperclipSkillEntry[]> {
  const root = await resolvePaperclipSkillsDir(moduleDir, additionalCandidates);
  if (!root) return [];

  try {
    const entries = await fs.readdir(root, { withFileTypes: true });
    return entries
      .filter((entry) => entry.isDirectory())
      .map((entry) => ({
        name: entry.name,
        source: path.join(root, entry.name),
      }));
  } catch {
    return [];
  }
}

export async function readPaperclipSkillMarkdown(
  moduleDir: string,
  skillName: string,
): Promise<string | null> {
  const normalized = skillName.trim().toLowerCase();
  if (!normalized) return null;

  const entries = await listPaperclipSkillEntries(moduleDir);
  const match = entries.find((entry) => entry.name === normalized);
  if (!match) return null;

  try {
    return await fs.readFile(path.join(match.source, "SKILL.md"), "utf8");
  } catch {
    return null;
  }
}

export async function ensurePaperclipSkillSymlink(
  source: string,
  target: string,
  linkSkill: (source: string, target: string) => Promise<void> = (linkSource, linkTarget) =>
    fs.symlink(linkSource, linkTarget),
): Promise<"created" | "repaired" | "skipped"> {
  const existing = await fs.lstat(target).catch(() => null);
  if (!existing) {
    await linkSkill(source, target);
    return "created";
  }

  if (!existing.isSymbolicLink()) {
    return "skipped";
  }

  const linkedPath = await fs.readlink(target).catch(() => null);
  if (!linkedPath) return "skipped";

  const resolvedLinkedPath = path.resolve(path.dirname(target), linkedPath);
  if (resolvedLinkedPath === source) {
    return "skipped";
  }

  const linkedPathExists = await fs.stat(resolvedLinkedPath).then(() => true).catch(() => false);
  if (linkedPathExists) {
    return "skipped";
  }

  await fs.unlink(target);
  await linkSkill(source, target);
  return "repaired";
}

export async function removeMaintainerOnlySkillSymlinks(
  skillsHome: string,
  allowedSkillNames: Iterable<string>,
): Promise<string[]> {
  const allowed = new Set(Array.from(allowedSkillNames));
  try {
    const entries = await fs.readdir(skillsHome, { withFileTypes: true });
    const removed: string[] = [];
    for (const entry of entries) {
      if (allowed.has(entry.name)) continue;

      const target = path.join(skillsHome, entry.name);
      const existing = await fs.lstat(target).catch(() => null);
      if (!existing?.isSymbolicLink()) continue;

      const linkedPath = await fs.readlink(target).catch(() => null);
      if (!linkedPath) continue;

      const resolvedLinkedPath = path.isAbsolute(linkedPath)
        ? linkedPath
        : path.resolve(path.dirname(target), linkedPath);
      if (
        !isMaintainerOnlySkillTarget(linkedPath) &&
        !isMaintainerOnlySkillTarget(resolvedLinkedPath)
      ) {
        continue;
      }

      await fs.unlink(target);
      removed.push(entry.name);
    }

    return removed;
  } catch {
    return [];
  }
}

export async function ensureCommandResolvable(command: string, cwd: string, env: NodeJS.ProcessEnv) {
  const resolved = await resolveCommandPath(command, cwd, env);
  if (resolved) return;
  if (command.includes("/") || command.includes("\\")) {
    const absolute = path.isAbsolute(command) ? command : path.resolve(cwd, command);
    throw new Error(`Command is not executable: "${command}" (resolved: "${absolute}")`);
  }
  throw new Error(`Command not found in PATH: "${command}"`);
}

export async function runChildProcess(
  runId: string,
  command: string,
  args: string[],
  opts: {
    cwd: string;
    env: Record<string, string>;
    timeoutSec: number;
    graceSec: number;
    onLog: (stream: "stdout" | "stderr", chunk: string) => Promise<void>;
    onLogError?: (err: unknown, runId: string, message: string) => void;
    stdin?: string;
  },
): Promise<RunProcessResult> {
  const onLogError = opts.onLogError ?? ((err, id, msg) => console.warn({ err, runId: id }, msg));

  return new Promise<RunProcessResult>((resolve, reject) => {
    const rawMerged: NodeJS.ProcessEnv = { ...process.env, ...opts.env };

    // Strip Claude Code nesting-guard env vars so spawned `claude` processes
    // don't refuse to start with "cannot be launched inside another session".
    // These vars leak in when the Paperclip server itself is started from
    // within a Claude Code session (e.g. `npx paperclipai run` in a terminal
    // owned by Claude Code) or when cron inherits a contaminated shell env.
    const CLAUDE_CODE_NESTING_VARS = [
      "CLAUDECODE",
      "CLAUDE_CODE_ENTRYPOINT",
      "CLAUDE_CODE_SESSION",
      "CLAUDE_CODE_PARENT_SESSION",
    ] as const;
    for (const key of CLAUDE_CODE_NESTING_VARS) {
      delete rawMerged[key];
    }

    const mergedEnv = ensurePathInEnv(rawMerged);
    void resolveSpawnTarget(command, args, opts.cwd, mergedEnv)
      .then((target) => {
        const child = spawn(target.command, target.args, {
          cwd: opts.cwd,
          env: mergedEnv,
          shell: false,
          stdio: [opts.stdin != null ? "pipe" : "ignore", "pipe", "pipe"],
        }) as ChildProcessWithEvents;

        if (opts.stdin != null && child.stdin) {
          child.stdin.write(opts.stdin);
          child.stdin.end();
        }

        runningProcesses.set(runId, { child, graceSec: opts.graceSec });

        let timedOut = false;
        let stdout = "";
        let stderr = "";
        let logChain: Promise<void> = Promise.resolve();

        const timeout =
          opts.timeoutSec > 0
            ? setTimeout(() => {
                timedOut = true;
                child.kill("SIGTERM");
                setTimeout(() => {
                  if (!child.killed) {
                    child.kill("SIGKILL");
                  }
                }, Math.max(1, opts.graceSec) * 1000);
              }, opts.timeoutSec * 1000)
            : null;

        child.stdout?.on("data", (chunk: unknown) => {
          const text = String(chunk);
          stdout = appendWithCap(stdout, text);
          logChain = logChain
            .then(() => opts.onLog("stdout", text))
            .catch((err) => onLogError(err, runId, "failed to append stdout log chunk"));
        });

        child.stderr?.on("data", (chunk: unknown) => {
          const text = String(chunk);
          stderr = appendWithCap(stderr, text);
          logChain = logChain
            .then(() => opts.onLog("stderr", text))
            .catch((err) => onLogError(err, runId, "failed to append stderr log chunk"));
        });

        child.on("error", (err: Error) => {
          if (timeout) clearTimeout(timeout);
          runningProcesses.delete(runId);
          const errno = (err as NodeJS.ErrnoException).code;
          const pathValue = mergedEnv.PATH ?? mergedEnv.Path ?? "";
          const msg =
            errno === "ENOENT"
              ? `Failed to start command "${command}" in "${opts.cwd}". Verify adapter command, working directory, and PATH (${pathValue}).`
              : `Failed to start command "${command}" in "${opts.cwd}": ${err.message}`;
          reject(new Error(msg));
        });

        child.on("close", (code: number | null, signal: NodeJS.Signals | null) => {
          if (timeout) clearTimeout(timeout);
          runningProcesses.delete(runId);
          void logChain.finally(() => {
            resolve({
              exitCode: code,
              signal,
              timedOut,
              stdout,
              stderr,
            });
          });
        });
      })
      .catch(reject);
  });
}
