CoderCLIManager.kt

package com.coder.gateway.cli

import com.coder.gateway.cli.ex.MissingVersionException
import com.coder.gateway.cli.ex.ResponseException
import com.coder.gateway.cli.ex.SSHConfigFormatException
import com.coder.gateway.settings.CoderSettings
import com.coder.gateway.settings.CoderSettingsState
import com.coder.gateway.util.CoderHostnameVerifier
import com.coder.gateway.util.InvalidVersionException
import com.coder.gateway.util.OS
import com.coder.gateway.util.SemVer
import com.coder.gateway.util.coderSocketFactory
import com.coder.gateway.util.escape
import com.coder.gateway.util.escapeSubcommand
import com.coder.gateway.util.getHeaders
import com.coder.gateway.util.getOS
import com.coder.gateway.util.safeHost
import com.coder.gateway.util.sha1
import com.intellij.openapi.diagnostic.Logger
import com.squareup.moshi.Json
import com.squareup.moshi.JsonClass
import com.squareup.moshi.JsonDataException
import com.squareup.moshi.Moshi
import org.zeroturnaround.exec.ProcessExecutor
import java.io.EOFException
import java.io.FileInputStream
import java.io.FileNotFoundException
import java.net.ConnectException
import java.net.HttpURLConnection
import java.net.URL
import java.nio.file.Files
import java.nio.file.Path
import java.nio.file.StandardCopyOption
import java.util.zip.GZIPInputStream
import javax.net.ssl.HttpsURLConnection

/**
 * Version output from the CLI's version command.
 */
@JsonClass(generateAdapter = true)
internal data class Version(
    @Json(name = "version") val version: String,
)

/**
 * Do as much as possible to get a valid, up-to-date CLI.
 *
 * 1. Read the binary directory for the provided URL.
 * 2. Abort if we already have an up-to-date version.
 * 3. Download the binary using an ETag.
 * 4. Abort if we get a 304 (covers cases where the binary is older and does not
 *    have a version command).
 * 5. Download on top of the existing binary.
 * 6. Since the binary directory can be read-only, if downloading fails, start
 *    from step 2 with the data directory.
 */
fun ensureCLI(
    deploymentURL: URL,
    buildVersion: String,
    settings: CoderSettings,
    indicator: ((t: String) -> Unit)? = null,
): CoderCLIManager {
    val cli = CoderCLIManager(deploymentURL, settings)

    // Short-circuit if we already have the expected version.  This
    // lets us bypass the 304 which is slower and may not be
    // supported if the binary is downloaded from alternate sources.
    // For CLIs without the JSON output flag we will fall back to
    // the 304 method.
    val cliMatches = cli.matchesVersion(buildVersion)
    if (cliMatches == true) {
        return cli
    }

    // If downloads are enabled download the new version.
    if (settings.enableDownloads) {
        indicator?.invoke("Downloading Coder CLI...")
        try {
            cli.download()
            return cli
        } catch (e: java.nio.file.AccessDeniedException) {
            // Might be able to fall back to the data directory.
            val binPath = settings.binPath(deploymentURL)
            val dataDir = settings.dataDir(deploymentURL)
            if (binPath.parent == dataDir || !settings.enableBinaryDirectoryFallback) {
                throw e
            }
        }
    }

    // Try falling back to the data directory.
    val dataCLI = CoderCLIManager(deploymentURL, settings, true)
    val dataCLIMatches = dataCLI.matchesVersion(buildVersion)
    if (dataCLIMatches == true) {
        return dataCLI
    }

    if (settings.enableDownloads) {
        indicator?.invoke("Downloading Coder CLI...")
        dataCLI.download()
        return dataCLI
    }

    // Prefer the binary directory unless the data directory has a
    // working binary and the binary directory does not.
    return if (cliMatches == null && dataCLIMatches != null) dataCLI else cli
}

/**
 * The supported features of the CLI.
 */
data class Features(
    val disableAutostart: Boolean = false,
    val reportWorkspaceUsage: Boolean = false,
)

/**
 * Manage the CLI for a single deployment.
 */
class CoderCLIManager(
    // The URL of the deployment this CLI is for.
    private val deploymentURL: URL,
    // Plugin configuration.
    private val settings: CoderSettings = CoderSettings(CoderSettingsState()),
    // If the binary directory is not writable, this can be used to force the
    // manager to download to the data directory instead.
    forceDownloadToData: Boolean = false,
) {
    val remoteBinaryURL: URL = settings.binSource(deploymentURL)
    val localBinaryPath: Path = settings.binPath(deploymentURL, forceDownloadToData)
    val coderConfigPath: Path = settings.dataDir(deploymentURL).resolve("config")

    /**
     * Download the CLI from the deployment if necessary.
     */
    fun download(): Boolean {
        val eTag = getBinaryETag()
        val conn = remoteBinaryURL.openConnection() as HttpURLConnection
        if (settings.headerCommand.isNotBlank()) {
            val headersFromHeaderCommand = getHeaders(deploymentURL, settings.headerCommand)
            for ((key, value) in headersFromHeaderCommand) {
                conn.setRequestProperty(key, value)
            }
        }
        if (eTag != null) {
            logger.info("Found existing binary at $localBinaryPath; calculated hash as $eTag")
            conn.setRequestProperty("If-None-Match", "\"$eTag\"")
        }
        conn.setRequestProperty("Accept-Encoding", "gzip")
        if (conn is HttpsURLConnection) {
            conn.sslSocketFactory = coderSocketFactory(settings.tls)
            conn.hostnameVerifier = CoderHostnameVerifier(settings.tls.altHostname)
        }

        try {
            conn.connect()
            logger.info("GET ${conn.responseCode} $remoteBinaryURL")
            when (conn.responseCode) {
                HttpURLConnection.HTTP_OK -> {
                    logger.info("Downloading binary to $localBinaryPath")
                    Files.createDirectories(localBinaryPath.parent)
                    conn.inputStream.use {
                        Files.copy(
                            if (conn.contentEncoding == "gzip") GZIPInputStream(it) else it,
                            localBinaryPath,
                            StandardCopyOption.REPLACE_EXISTING,
                        )
                    }
                    if (getOS() != OS.WINDOWS) {
                        localBinaryPath.toFile().setExecutable(true)
                    }
                    return true
                }

                HttpURLConnection.HTTP_NOT_MODIFIED -> {
                    logger.info("Using cached binary at $localBinaryPath")
                    return false
                }
            }
        } catch (e: ConnectException) {
            // Add the URL so this is more easily debugged.
            throw ConnectException("${e.message} to $remoteBinaryURL")
        } finally {
            conn.disconnect()
        }
        throw ResponseException("Unexpected response from $remoteBinaryURL", conn.responseCode)
    }

    /**
     * Return the entity tag for the binary on disk, if any.
     */
    private fun getBinaryETag(): String? = try {
        sha1(FileInputStream(localBinaryPath.toFile()))
    } catch (e: FileNotFoundException) {
        null
    } catch (e: Exception) {
        logger.warn("Unable to calculate hash for $localBinaryPath", e)
        null
    }

    /**
     * Use the provided token to authenticate the CLI.
     */
    fun login(token: String): String {
        logger.info("Storing CLI credentials in $coderConfigPath")
        return exec(
            "login",
            deploymentURL.toString(),
            "--token",
            token,
            "--global-config",
            coderConfigPath.toString(),
        )
    }

    /**
     * Configure SSH to use this binary.
     *
     * This can take supported features for testing purposes only.
     */
    fun configSsh(
        workspaceNames: Set<String>,
        feats: Features = features,
    ) {
        writeSSHConfig(modifySSHConfig(readSSHConfig(), workspaceNames, feats))
    }

    /**
     * Return the contents of the SSH config or null if it does not exist.
     */
    private fun readSSHConfig(): String? = try {
        settings.sshConfigPath.toFile().readText()
    } catch (e: FileNotFoundException) {
        null
    }

    /**
     * Given an existing SSH config modify it to add or remove the config for
     * this deployment and return the modified config or null if it does not
     * need to be modified.
     *
     * If features are not provided, calculate them based on the binary
     * version.
     */
    private fun modifySSHConfig(
        contents: String?,
        workspaceNames: Set<String>,
        feats: Features,
    ): String? {
        val host = deploymentURL.safeHost()
        val startBlock = "# --- START CODER JETBRAINS $host"
        val endBlock = "# --- END CODER JETBRAINS $host"
        val isRemoving = workspaceNames.isEmpty()
        val baseArgs =
            listOfNotNull(
                escape(localBinaryPath.toString()),
                "--global-config",
                escape(coderConfigPath.toString()),
                if (settings.headerCommand.isNotBlank()) "--header-command" else null,
                if (settings.headerCommand.isNotBlank()) escapeSubcommand(settings.headerCommand) else null,
                "ssh",
                "--stdio",
                if (settings.disableAutostart && feats.disableAutostart) "--disable-autostart" else null,
            )
        val proxyArgs = baseArgs + listOfNotNull(
            if (settings.sshLogDirectory.isNotBlank()) "--log-dir" else null,
            if (settings.sshLogDirectory.isNotBlank()) escape(settings.sshLogDirectory) else null,
            if (feats.reportWorkspaceUsage) "--usage-app=jetbrains" else null,
        )
        val backgroundProxyArgs = baseArgs + listOfNotNull(if (feats.reportWorkspaceUsage) "--usage-app=disable" else null)
        val extraConfig =
            if (settings.sshConfigOptions.isNotBlank()) {
                "\n" + settings.sshConfigOptions.prependIndent("  ")
            } else {
                ""
            }
        val blockContent =
            workspaceNames.joinToString(
                System.lineSeparator(),
                startBlock + System.lineSeparator(),
                System.lineSeparator() + endBlock,
                transform = {
                    """
                    Host ${getHostName(deploymentURL, it)}
                      ProxyCommand ${proxyArgs.joinToString(" ")} $it
                      ConnectTimeout 0
                      StrictHostKeyChecking no
                      UserKnownHostsFile /dev/null
                      LogLevel ERROR
                      SetEnv CODER_SSH_SESSION_TYPE=JetBrains
                    """.trimIndent()
                        .plus(extraConfig)
                        .plus("\n")
                        .plus(
                            """
                            Host ${getBackgroundHostName(deploymentURL, it)}
                              ProxyCommand ${backgroundProxyArgs.joinToString(" ")} $it
                              ConnectTimeout 0
                              StrictHostKeyChecking no
                              UserKnownHostsFile /dev/null
                              LogLevel ERROR
                              SetEnv CODER_SSH_SESSION_TYPE=JetBrains
                            """.trimIndent()
                                .plus(extraConfig),
                        ).replace("\n", System.lineSeparator())
                },
            )

        if (contents == null) {
            logger.info("No existing SSH config to modify")
            return blockContent + System.lineSeparator()
        }

        val start = "(\\s*)$startBlock".toRegex().find(contents)
        val end = "$endBlock(\\s*)".toRegex().find(contents)

        if (start == null && end == null && isRemoving) {
            logger.info("No workspaces and no existing config blocks to remove")
            return null
        }

        if (start == null && end == null) {
            logger.info("Appending config block")
            val toAppend =
                if (contents.isEmpty()) {
                    blockContent
                } else {
                    listOf(
                        contents,
                        blockContent,
                    ).joinToString(System.lineSeparator())
                }
            return toAppend + System.lineSeparator()
        }

        if (start == null) {
            throw SSHConfigFormatException("End block exists but no start block")
        }
        if (end == null) {
            throw SSHConfigFormatException("Start block exists but no end block")
        }
        if (start.range.first > end.range.first) {
            throw SSHConfigFormatException("Start block found after end block")
        }

        if (isRemoving) {
            logger.info("No workspaces; removing config block")
            return listOf(
                contents.substring(0, start.range.first),
                // Need to keep the trailing newline(s) if we are not at the
                // front of the file otherwise the before and after lines would
                // get joined.
                if (start.range.first > 0) end.groupValues[1] else "",
                contents.substring(end.range.last + 1),
            ).joinToString("")
        }

        logger.info("Replacing existing config block")
        return listOf(
            contents.substring(0, start.range.first),
            start.groupValues[1], // Leading newline(s).
            blockContent,
            end.groupValues[1], // Trailing newline(s).
            contents.substring(end.range.last + 1),
        ).joinToString("")
    }

    /**
     * Write the provided SSH config or do nothing if null.
     */
    private fun writeSSHConfig(contents: String?) {
        if (contents != null) {
            settings.sshConfigPath.parent.toFile().mkdirs()
            settings.sshConfigPath.toFile().writeText(contents)
            // The Coder cli will *not* create the log directory.
            if (settings.sshLogDirectory.isNotBlank()) {
                Path.of(settings.sshLogDirectory).toFile().mkdirs()
            }
        }
    }

    /**
     * Return the binary version.
     *
     * Throws if it could not be determined.
     */
    fun version(): SemVer {
        val raw = exec("version", "--output", "json")
        try {
            val json = Moshi.Builder().build().adapter(Version::class.java).fromJson(raw)
            if (json?.version == null || json.version.isBlank()) {
                throw MissingVersionException("No version found in output")
            }
            return SemVer.parse(json.version)
        } catch (exception: JsonDataException) {
            throw MissingVersionException("No version found in output")
        } catch (exception: EOFException) {
            throw MissingVersionException("No version found in output")
        }
    }

    /**
     * Like version(), but logs errors instead of throwing them.
     */
    private fun tryVersion(): SemVer? = try {
        version()
    } catch (e: Exception) {
        when (e) {
            is InvalidVersionException -> {
                logger.info("Got invalid version from $localBinaryPath: ${e.message}")
            }
            else -> {
                // An error here most likely means the CLI does not exist or
                // it executed successfully but output no version which
                // suggests it is not the right binary.
                logger.info("Unable to determine $localBinaryPath version: ${e.message}")
            }
        }
        null
    }

    /**
     * Returns true if the CLI has the same major/minor/patch version as the
     * provided version, false if it does not match, or null if the CLI version
     * could not be determined because the binary could not be executed or the
     * version could not be parsed.
     */
    fun matchesVersion(rawBuildVersion: String): Boolean? {
        val cliVersion = tryVersion() ?: return null
        val buildVersion =
            try {
                SemVer.parse(rawBuildVersion)
            } catch (e: InvalidVersionException) {
                logger.info("Got invalid build version: $rawBuildVersion")
                return null
            }

        val matches = cliVersion == buildVersion
        logger.info("$localBinaryPath version $cliVersion matches $buildVersion: $matches")
        return matches
    }

    private fun exec(vararg args: String): String {
        val stdout =
            ProcessExecutor()
                .command(localBinaryPath.toString(), *args)
                .environment("CODER_HEADER_COMMAND", settings.headerCommand)
                .exitValues(0)
                .readOutput(true)
                .execute()
                .outputUTF8()
        val redactedArgs = listOf(*args).joinToString(" ").replace(tokenRegex, "--token <redacted>")
        logger.info("`$localBinaryPath $redactedArgs`: $stdout")
        return stdout
    }

    val features: Features
        get() {
            val version = tryVersion()
            return if (version == null) {
                Features()
            } else {
                Features(
                    disableAutostart = version >= SemVer(2, 5, 0),
                    reportWorkspaceUsage = version >= SemVer(2, 13, 0),
                )
            }
        }

    companion object {
        val logger = Logger.getInstance(CoderCLIManager::class.java.simpleName)

        private val tokenRegex = "--token [^ ]+".toRegex()

        @JvmStatic
        fun getHostName(
            url: URL,
            workspaceName: String,
        ): String = "coder-jetbrains--$workspaceName--${url.safeHost()}"

        @JvmStatic
        fun getBackgroundHostName(
            url: URL,
            workspaceName: String,
        ): String = getHostName(url, workspaceName) + "--bg"

        @JvmStatic
        fun getBackgroundHostName(
            hostname: String,
        ): String = hostname + "--bg"
    }
}