import { execFile } from "node:child_process";
import fs from "node:fs/promises";
import path from "node:path";
import { promisify } from "node:util";
import { colorize, isRich, theme } from "../terminal/theme.js";
import {
  formatGatewayServiceDescription,
  resolveGatewaySystemdServiceName,
} from "./constants.js";
import { parseKeyValueOutput } from "./runtime-parse.js";
import type { GatewayServiceRuntime } from "./service-runtime.js";
import { resolveHomeDir } from "./paths.js";
import {
  enableSystemdUserLinger,
  readSystemdUserLingerStatus,
  type SystemdUserLingerStatus,
} from "./systemd-linger.js";
import {
  buildSystemdUnit,
  parseSystemdEnvAssignment,
  parseSystemdExecStart,
} from "./systemd-unit.js";

const execFileAsync = promisify(execFile);
const toPosixPath = (value: string) => value.replace(/\\/g, "/");

const formatLine = (label: string, value: string) => {
  const rich = isRich();
  return `${colorize(rich, theme.muted, `${label}:`)} ${colorize(rich, theme.command, value)}`;
};

function resolveSystemdUnitPathForName(
  env: Record<string, string | undefined>,
  name: string,
): string {
  const home = toPosixPath(resolveHomeDir(env));
  return path.posix.join(home, ".config", "systemd", "user", `${name}.service`);
}

function resolveSystemdSystemUnitPathForName(name: string): string {
  return `/etc/systemd/system/${name}.service`;
}

function resolveSystemdServiceName(env: Record<string, string | undefined>): string {
  const override = env.CLAWDBOT_SYSTEMD_UNIT?.trim();
  if (override) {
    return override.endsWith(".service") ? override.slice(0, -".service".length) : override;
  }
  return resolveGatewaySystemdServiceName(env.CLAWDBOT_PROFILE);
}

function resolveSystemdUnitPath(env: Record<string, string | undefined>): string {
  return resolveSystemdUnitPathForName(env, resolveSystemdServiceName(env));
}

function resolveSystemdSystemUnitPath(env: Record<string, string | undefined>): string {
  return resolveSystemdSystemUnitPathForName(resolveSystemdServiceName(env));
}

export function resolveSystemdUserUnitPath(env: Record<string, string | undefined>): string {
  return resolveSystemdUnitPath(env);
}

export function findLegacySystemdUnits(
  _env: Record<string, string | undefined>,
): Promise<string[]> {
  // TODO: Implement search for legacy unit names
  return Promise.resolve([]);
}

export function uninstallLegacySystemdUnits(
  _env: Record<string, string | undefined>,
  _units: string[],
): Promise<void> {
  // TODO: Implement removal of legacy units
  return Promise.resolve();
}

export { enableSystemdUserLinger, readSystemdUserLingerStatus };
export type { SystemdUserLingerStatus };

// Unit file parsing/rendering: see systemd-unit.ts

export async function readSystemdServiceExecStart(
  env: Record<string, string | undefined>,
): Promise<{
  programArguments: string[];
  workingDirectory?: string;
  environment?: Record<string, string>;
  sourcePath?: string;
} | null> {
  // Try user service first, then system service
  const userUnitPath = resolveSystemdUnitPath(env);
  const systemUnitPath = resolveSystemdSystemUnitPath(env);
  
  for (const unitPath of [userUnitPath, systemUnitPath]) {
    try {
      const content = await fs.readFile(unitPath, "utf8");
      let execStart = "";
      let workingDirectory = "";
      const environment: Record<string, string> = {};
      for (const rawLine of content.split("\n")) {
        const line = rawLine.trim();
        if (!line || line.startsWith("#")) continue;
        if (line.startsWith("ExecStart=")) {
          execStart = line.slice("ExecStart=".length).trim();
        } else if (line.startsWith("WorkingDirectory=")) {
          workingDirectory = line.slice("WorkingDirectory=".length).trim();
        } else if (line.startsWith("Environment=")) {
          const raw = line.slice("Environment=".length).trim();
          const parsed = parseSystemdEnvAssignment(raw);
          if (parsed) environment[parsed.key] = parsed.value;
        }
      }
      if (!execStart) continue;
      const programArguments = parseSystemdExecStart(execStart);
      return {
        programArguments,
        ...(workingDirectory ? { workingDirectory } : {}),
        ...(Object.keys(environment).length > 0 ? { environment } : {}),
        sourcePath: unitPath,
      };
    } catch {
      // Continue to next path
    }
  }
  return null;
}

async function execSystemctl(
  args: string[],
  options?: { useSudo?: boolean },
): Promise<{ stdout: string; stderr: string; code: number }> {
  try {
    const cmd = options?.useSudo ? "sudo" : "systemctl";
    const cmdArgs = options?.useSudo ? ["systemctl", ...args] : args;
    const { stdout, stderr } = await execFileAsync(cmd, cmdArgs, {
      encoding: "utf8",
    });
    return {
      stdout: String(stdout ?? ""),
      stderr: String(stderr ?? ""),
      code: 0,
    };
  } catch (error) {
    const e = error as {
      stdout?: unknown;
      stderr?: unknown;
      code?: unknown;
      message?: unknown;
    };
    return {
      stdout: typeof e.stdout === "string" ? e.stdout : "",
      stderr:
        typeof e.stderr === "string" ? e.stderr : typeof e.message === "string" ? e.message : "",
      code: typeof e.code === "number" ? e.code : 1,
    };
  }
}

export async function isSystemdUserServiceAvailable(): Promise<boolean> {
  const res = await execSystemctl(["--user", "status"]);
  if (res.code === 0) return true;
  const detail = `${res.stderr} ${res.stdout}`.toLowerCase();
  if (!detail) return false;
  if (detail.includes("not found")) return false;
  if (detail.includes("failed to connect")) return false;
  if (detail.includes("not been booted")) return false;
  if (detail.includes("no such file or directory")) return false;
  if (detail.includes("not supported")) return false;
  return false;
}

export async function isSystemdSystemServiceAvailable(): Promise<boolean> {
  // Check if we can run systemctl (may require sudo)
  const res = await execSystemctl(["status"], { useSudo: true });
  // If it doesn't error with "command not found", systemd is available
  const detail = `${res.stderr} ${res.stdout}`.toLowerCase();
  if (detail.includes("not found")) return false;
  if (detail.includes("command not found")) return false;
  return true;
}

async function assertSystemdAvailable() {
  const res = await execSystemctl(["--user", "status"]);
  if (res.code === 0) return;
  const detail = res.stderr || res.stdout;
  if (detail.toLowerCase().includes("not found")) {
    throw new Error("systemctl not available; systemd user services are required on Linux.");
  }
  throw new Error(`systemctl --user unavailable: ${detail || "unknown error"}`.trim());
}

export async function installSystemdService({
  env,
  stdout,
  programArguments,
  workingDirectory,
  environment,
  description,
}: {
  env: Record<string, string | undefined>;
  stdout: NodeJS.WritableStream;
  programArguments: string[];
  workingDirectory?: string;
  environment?: Record<string, string | undefined>;
  description?: string;
}): Promise<{ unitPath: string }> {
  await assertSystemdAvailable();

  const unitPath = resolveSystemdUnitPath(env);
  await fs.mkdir(path.dirname(unitPath), { recursive: true });
  const serviceDescription =
    description ??
    formatGatewayServiceDescription({
      profile: env.CLAWDBOT_PROFILE,
      version: environment?.CLAWDBOT_SERVICE_VERSION ?? env.CLAWDBOT_SERVICE_VERSION,
    });
  const unit = buildSystemdUnit({
    description: serviceDescription,
    programArguments,
    workingDirectory,
    environment,
  });
  await fs.writeFile(unitPath, unit, "utf8");

  const serviceName = resolveGatewaySystemdServiceName(env.CLAWDBOT_PROFILE);
  const unitName = `${serviceName}.service`;
  const reload = await execSystemctl(["--user", "daemon-reload"]);
  if (reload.code !== 0) {
    throw new Error(`systemctl daemon-reload failed: ${reload.stderr || reload.stdout}`.trim());
  }

  const enable = await execSystemctl(["--user", "enable", unitName]);
  if (enable.code !== 0) {
    throw new Error(`systemctl enable failed: ${enable.stderr || enable.stdout}`.trim());
  }

  const restart = await execSystemctl(["--user", "restart", unitName]);
  if (restart.code !== 0) {
    throw new Error(`systemctl restart failed: ${restart.stderr || restart.stdout}`.trim());
  }

  // Ensure we don't end up writing to a clack spinner line (wizards show progress without a newline).
  stdout.write("\n");
  stdout.write(`${formatLine("Installed systemd service", unitPath)}\n`);
  return { unitPath };
}

export async function uninstallSystemdService({
  env,
  stdout,
}: {
  env: Record<string, string | undefined>;
  stdout: NodeJS.WritableStream;
}): Promise<void> {
  await assertSystemdAvailable();
  const serviceName = resolveSystemdServiceName(env);
  const unitName = `${serviceName}.service`;
  await execSystemctl(["--user", "disable", "--now", unitName]);

  const unitPath = resolveSystemdUnitPath(env);
  try {
    await fs.unlink(unitPath);
    stdout.write(`${formatLine("Removed systemd service", unitPath)}\n`);
  } catch {
    stdout.write(`Systemd service not found at ${unitPath}\n`);
  }
}

export async function stopSystemdService({
  stdout,
  env,
}: {
  stdout: NodeJS.WritableStream;
  env?: Record<string, string | undefined>;
}): Promise<void> {
  // Check if user service exists first, otherwise try system service
  const serviceName = resolveSystemdServiceName(env ?? {});
  const unitName = `${serviceName}.service`;
  
  // Try user service first
  const userRes = await execSystemctl(["--user", "stop", unitName]);
  if (userRes.code === 0) {
    stdout.write(`${formatLine("Stopped systemd user service", unitName)}\n`);
    return;
  }
  
  // Try system service
  const systemRes = await execSystemctl(["stop", unitName], { useSudo: true });
  if (systemRes.code === 0) {
    stdout.write(`${formatLine("Stopped systemd system service", unitName)}\n`);
    return;
  }
  
  throw new Error(`systemctl stop failed: ${systemRes.stderr || systemRes.stdout}`.trim());
}

export async function restartSystemdService({
  stdout,
  env,
}: {
  stdout: NodeJS.WritableStream;
  env?: Record<string, string | undefined>;
}): Promise<void> {
  const serviceName = resolveSystemdServiceName(env ?? {});
  const unitName = `${serviceName}.service`;
  
  // Try user service first
  const userRes = await execSystemctl(["--user", "restart", unitName]);
  if (userRes.code === 0) {
    stdout.write(`${formatLine("Restarted systemd user service", unitName)}\n`);
    return;
  }
  
  // Try system service
  const systemRes = await execSystemctl(["restart", unitName], { useSudo: true });
  if (systemRes.code === 0) {
    stdout.write(`${formatLine("Restarted systemd system service", unitName)}\n`);
    return;
  }
  
  throw new Error(`systemctl restart failed: ${systemRes.stderr || systemRes.stdout}`.trim());
}

export async function isSystemdServiceEnabled(args: {
  env?: Record<string, string | undefined>;
}): Promise<boolean> {
  const serviceName = resolveSystemdServiceName(args.env ?? {});
  const unitName = `${serviceName}.service`;
  
  // Check user service
  const userRes = await execSystemctl(["--user", "is-enabled", unitName]);
  if (userRes.code === 0) return true;
  
  // Check system service
  const systemRes = await execSystemctl(["is-enabled", unitName], { useSudo: true });
  return systemRes.code === 0;
}

export type SystemdServiceInfo = {
  activeState?: string;
  subState?: string;
  mainPid?: number;
  execMainStatus?: number;
  execMainCode?: string;
};

export function parseSystemdShow(output: string): SystemdServiceInfo {
  const entries = parseKeyValueOutput(output, "=");
  const info: SystemdServiceInfo = {};
  const activeState = entries.activestate;
  if (activeState) info.activeState = activeState;
  const subState = entries.substate;
  if (subState) info.subState = subState;
  const mainPidValue = entries.mainpid;
  if (mainPidValue) {
    const pid = Number.parseInt(mainPidValue, 10);
    if (Number.isFinite(pid) && pid > 0) info.mainPid = pid;
  }
  const execMainStatusValue = entries.execmainstatus;
  if (execMainStatusValue) {
    const status = Number.parseInt(execMainStatusValue, 10);
    if (Number.isFinite(status)) info.execMainStatus = status;
  }
  const execMainCode = entries.execmaincode;
  if (execMainCode) info.execMainCode = execMainCode;
  return info;
}

export async function readSystemdServiceRuntime(
  env: Record<string, string | undefined> = process.env as Record<string, string | undefined>,
): Promise<GatewayServiceRuntime> {
  const serviceName = resolveSystemdServiceName(env);
  const unitName = `${serviceName}.service`;
  
  // Try user service first
  const userRes = await execSystemctl([
    "--user",
    "show",
    unitName,
    "--no-page",
    "--property",
    "ActiveState,SubState,MainPID,ExecMainStatus,ExecMainCode",
  ]);
  
  if (userRes.code === 0) {
    const parsed = parseSystemdShow(userRes.stdout || "");
    const activeState = parsed.activeState?.toLowerCase();
    const status = activeState === "active" ? "running" : activeState ? "stopped" : "unknown";
    return {
      status,
      state: parsed.activeState,
      subState: parsed.subState,
      pid: parsed.mainPid,
      lastExitStatus: parsed.execMainStatus,
      lastRunResult: parsed.execMainCode,
    };
  }
  
  // Try system service
  const systemRes = await execSystemctl(
    [
      "show",
      unitName,
      "--no-page",
      "--property",
      "ActiveState,SubState,MainPID,ExecMainStatus,ExecMainCode",
    ],
    { useSudo: true },
  );
  
  if (systemRes.code === 0) {
    const parsed = parseSystemdShow(systemRes.stdout || "");
    const activeState = parsed.activeState?.toLowerCase();
    const status = activeState === "active" ? "running" : activeState ? "stopped" : "unknown";
    return {
      status,
      state: parsed.activeState,
      subState: parsed.subState,
      pid: parsed.mainPid,
      lastExitStatus: parsed.execMainStatus,
      lastRunResult: parsed.execMainCode,
    };
  }
  
  const detail = (systemRes.stderr || systemRes.stdout).trim();
  const missing = detail.toLowerCase().includes("not found");
  return {
    status: missing ? "stopped" : "unknown",
    detail: detail || undefined,
    missingUnit: missing,
  };
}