import type { IIdeSshTarget, IRemoteProbeResult } from '@git.zone/ide-protocol';
import * as plugins from './plugins.js';

export interface ISshHostConfig {
  alias: string;
  patterns: string[];
  hostName?: string;
  user?: string;
  port?: number;
  identityFiles: string[];
  proxyJump?: string;
  forwardAgent?: boolean;
  raw: Record<string, string[]>;
}

export interface ISshRunOptions {
  executable?: string;
  timeoutMs?: number;
  batchMode?: boolean;
  cwd?: string;
  env?: NodeJS.ProcessEnv;
}

export interface ISshRunResult {
  exitCode: number;
  stdout: string;
  stderr: string;
}

export interface ISshTunnelOptions extends ISshRunOptions {
  localHost?: string;
  localPort: number;
  remoteHost?: string;
  remotePort: number;
}

export interface ISshTunnelHandle {
  readonly target: IIdeSshTarget;
  readonly localHost: string;
  readonly localPort: number;
  readonly remoteHost: string;
  readonly remotePort: number;
  readonly processId: number | undefined;
  dispose(signal?: NodeJS.Signals): Promise<void>;
}

const directiveAliases: Record<string, keyof ISshHostConfig | 'identityFiles'> = {
  hostname: 'hostName',
  user: 'user',
  port: 'port',
  identityfile: 'identityFiles',
  proxyjump: 'proxyJump',
  forwardagent: 'forwardAgent',
};

export const defaultSshConfigPath = () => plugins.path.join(plugins.os.homedir(), '.ssh', 'config');

export const expandHome = (filePath: string) => {
  if (filePath === '~') {
    return plugins.os.homedir();
  }

  if (filePath.startsWith('~/')) {
    return plugins.path.join(plugins.os.homedir(), filePath.slice(2));
  }

  return filePath;
};

export const parseSshConfig = (configText: string): ISshHostConfig[] => {
  const hosts: ISshHostConfig[] = [];
  let currentHosts: ISshHostConfig[] = [];

  for (const rawLine of configText.split(/\r?\n/)) {
    const line = stripSshComment(rawLine).trim();
    if (!line) {
      continue;
    }

    const tokens = tokenizeSshConfigLine(line);
    if (tokens.length === 0) {
      continue;
    }

    const key = tokens[0]!.toLowerCase();
    const values = tokens.slice(1);
    if (key === 'host') {
      currentHosts = values.map((alias) => ({
        alias,
        patterns: values,
        identityFiles: [],
        raw: {},
      }));
      hosts.push(...currentHosts);
      continue;
    }

    for (const host of currentHosts) {
      host.raw[key] = [...(host.raw[key] ?? []), ...values];
      applySshDirective(host, key, values);
    }
  }

  return hosts;
};

export const readSshConfig = async (filePath = defaultSshConfigPath()) => {
  try {
    const configText = await plugins.fs.readFile(expandHome(filePath), 'utf8');
    return parseSshConfig(configText);
  } catch (error) {
    const nodeError = error as NodeJS.ErrnoException;
    if (nodeError.code === 'ENOENT') {
      return [];
    }
    throw error;
  }
};

export const listConnectableHosts = (hosts: ISshHostConfig[]) => {
  return hosts.filter((host) => !isWildcardHostPattern(host.alias) && !host.alias.startsWith('!'));
};

export const buildSshDestination = (target: Pick<IIdeSshTarget, 'hostAlias' | 'user'>) => {
  return target.user ? `${target.user}@${target.hostAlias}` : target.hostAlias;
};

export const buildSshArgs = (
  target: IIdeSshTarget,
  remoteCommand?: string,
  options: ISshRunOptions = {},
) => {
  const args = buildSshOptionArgs(target, options);
  args.push(buildSshDestination(target));
  if (remoteCommand) {
    args.push(remoteCommand);
  }
  return args;
};

export const runSshCommand = async (
  target: IIdeSshTarget,
  remoteCommand: string,
  options: ISshRunOptions = {},
): Promise<ISshRunResult> => {
  const executable = options.executable ?? 'ssh';
  const args = buildSshArgs(target, remoteCommand, options);

  return new Promise<ISshRunResult>((resolve, reject) => {
    const child = plugins.childProcess.spawn(executable, args, {
      cwd: options.cwd,
      env: options.env ?? process.env,
      shell: false,
      stdio: ['ignore', 'pipe', 'pipe'],
      windowsHide: true,
    });

    const stdout: Buffer[] = [];
    const stderr: Buffer[] = [];
    let finished = false;
    const timeout = options.timeoutMs
      ? setTimeout(() => {
          if (!finished) {
            child.kill('SIGTERM');
          }
        }, options.timeoutMs)
      : undefined;

    child.stdout.on('data', (chunk: Buffer) => stdout.push(chunk));
    child.stderr.on('data', (chunk: Buffer) => stderr.push(chunk));
    child.on('error', (error) => {
      finished = true;
      if (timeout) {
        clearTimeout(timeout);
      }
      reject(error);
    });
    child.on('close', (exitCode) => {
      finished = true;
      if (timeout) {
        clearTimeout(timeout);
      }
      resolve({
        exitCode: exitCode ?? 1,
        stdout: Buffer.concat(stdout).toString('utf8'),
        stderr: Buffer.concat(stderr).toString('utf8'),
      });
    });
  });
};

export const findFreePort = async (host = '127.0.0.1') => {
  return new Promise<number>((resolve, reject) => {
    const server = plugins.net.createServer();
    server.unref();
    server.on('error', reject);
    server.listen(0, host, () => {
      const address = server.address();
      server.close(() => {
        if (typeof address === 'object' && address) {
          resolve(address.port);
        } else {
          reject(new Error('Unable to allocate a free local port'));
        }
      });
    });
  });
};

export const startSshTunnel = (
  target: IIdeSshTarget,
  options: ISshTunnelOptions,
): ISshTunnelHandle => {
  const executable = options.executable ?? 'ssh';
  const localHost = options.localHost ?? '127.0.0.1';
  const remoteHost = options.remoteHost ?? '127.0.0.1';
  const forward = `${localHost}:${options.localPort}:${remoteHost}:${options.remotePort}`;
  const args = [
    ...buildSshOptionArgs(target, options),
    '-N',
    '-L',
    forward,
    buildSshDestination(target),
  ];
  const child = plugins.childProcess.spawn(executable, args, {
    cwd: options.cwd,
    env: options.env ?? process.env,
    shell: false,
    stdio: ['ignore', 'ignore', 'pipe'],
    windowsHide: true,
  });

  return {
    target,
    localHost,
    localPort: options.localPort,
    remoteHost,
    remotePort: options.remotePort,
    processId: child.pid,
    dispose: async (signal: NodeJS.Signals = 'SIGTERM') => {
      if (child.exitCode !== null || child.killed) {
        return;
      }

      await new Promise<void>((resolve) => {
        const timer = setTimeout(() => {
          if (!child.killed) {
            child.kill('SIGKILL');
          }
          resolve();
        }, 5000);
        child.once('close', () => {
          clearTimeout(timer);
          resolve();
        });
        child.kill(signal);
      });
    },
  };
};

export const probeRemoteHost = async (
  target: IIdeSshTarget,
  options: ISshRunOptions = {},
): Promise<IRemoteProbeResult> => {
  const command = [
    `printf 'platform=%s\\n' "$(uname -s 2>/dev/null || printf unknown)"`,
    `printf 'arch=%s\\n' "$(uname -m 2>/dev/null || printf unknown)"`,
    `printf 'homeDir=%s\\n' "$HOME"`,
    `printf 'shell=%s\\n' "$SHELL"`,
    `printf 'nodeVersion=%s\\n' "$(node --version 2>/dev/null || true)"`,
    `printf 'pnpmVersion=%s\\n' "$(pnpm --version 2>/dev/null || true)"`,
    `printf 'gitVersion=%s\\n' "$(git --version 2>/dev/null || true)"`,
    `printf 'opencodeVersion=%s\\n' "$(opencode --version 2>/dev/null || true)"`,
  ].join('; ');

  const result = await runSshCommand(target, command, options);
  const fields = parseKeyValueLines(result.stdout);
  const errors: string[] = [];
  if (result.exitCode !== 0) {
    errors.push(result.stderr || `ssh exited with code ${result.exitCode}`);
  }

  return {
    ok: result.exitCode === 0,
    hostAlias: target.hostAlias,
    platform: fields.platform,
    arch: fields.arch,
    homeDir: fields.homeDir,
    shell: fields.shell,
    nodeVersion: fields.nodeVersion,
    pnpmVersion: fields.pnpmVersion,
    gitVersion: fields.gitVersion,
    opencodeVersion: fields.opencodeVersion,
    errors,
  };
};

const applySshDirective = (host: ISshHostConfig, key: string, values: string[]) => {
  const targetKey = directiveAliases[key];
  if (!targetKey || values.length === 0) {
    return;
  }

  if (targetKey === 'identityFiles') {
    host.identityFiles.push(...values.map(expandHome));
    return;
  }

  if (targetKey === 'port') {
    const port = Number(values[0]);
    if (Number.isInteger(port) && port > 0) {
      host.port = port;
    }
    return;
  }

  if (targetKey === 'forwardAgent') {
    host.forwardAgent = /^(yes|true)$/i.test(values[0]!);
    return;
  }

  if (targetKey === 'hostName') {
    host.hostName = values.join(' ');
  } else if (targetKey === 'user') {
    host.user = values.join(' ');
  } else if (targetKey === 'proxyJump') {
    host.proxyJump = values.join(' ');
  }
};

const buildSshOptionArgs = (target: IIdeSshTarget, options: ISshRunOptions = {}) => {
  const args: string[] = [];
  if (options.batchMode !== false) {
    args.push('-o', 'BatchMode=yes');
  }
  args.push('-o', 'ServerAliveInterval=30');
  args.push('-o', 'ServerAliveCountMax=3');
  if (target.port) {
    args.push('-p', `${target.port}`);
  }
  return args;
};

const stripSshComment = (line: string) => {
  let quote: string | undefined;
  for (let index = 0; index < line.length; index++) {
    const character = line[index];
    if ((character === '"' || character === "'") && line[index - 1] !== '\\') {
      quote = quote === character ? undefined : character;
      continue;
    }
    if (character === '#' && !quote) {
      return line.slice(0, index);
    }
  }
  return line;
};

const tokenizeSshConfigLine = (line: string) => {
  const tokens: string[] = [];
  let current = '';
  let quote: string | undefined;
  for (let index = 0; index < line.length; index++) {
    const character = line[index]!;
    if ((character === '"' || character === "'") && line[index - 1] !== '\\') {
      quote = quote === character ? undefined : character;
      continue;
    }
    if (/\s/.test(character) && !quote) {
      if (current) {
        tokens.push(current);
        current = '';
      }
      continue;
    }
    current += character;
  }
  if (current) {
    tokens.push(current);
  }
  return tokens;
};

const isWildcardHostPattern = (alias: string) => /[*?!]/.test(alias);

const parseKeyValueLines = (text: string) => {
  const fields: Record<string, string> = {};
  for (const line of text.split(/\r?\n/)) {
    const separator = line.indexOf('=');
    if (separator === -1) {
      continue;
    }
    fields[line.slice(0, separator)] = line.slice(separator + 1);
  }
  return fields;
};