/**
 * Java debugging through Microsoft java-debug, a jdtls bundle: jdtls starts its
 * DAP server (`vscode.java.startDebugSession`) and the session connects to that
 * port (`debugServer`). Application configurations are launched by java-debug;
 * JVMs started by Maven / Gradle with a JDWP agent are attached to.
 */
import { executeAction } from "@/platform/actions";
import { call, commands, IpcError, nextRequestId, type LaunchConfig, type RunConfig } from "@/platform/ipc";
import {
  consoleVmArgs,
  formatCompileErrors,
  isJvmApplication,
  joinJavaArgs,
  parseJavaArgs,
  prepareJavaLaunch,
  type JavaPreparation,
} from "@/platform/javaLaunch";
import { notifications } from "@/workbench/contributions";

export const JAVA_ADAPTER = "java-debug";
export const KOTLIN_ADAPTER = "kotlin-debug-adapter";

export function isJavaDebuggable(rc: RunConfig): boolean {
  return isJvmApplication(rc) && [JAVA_ADAPTER, KOTLIN_ADAPTER].includes(rc.debugAdapter ?? JAVA_ADAPTER);
}

function join(base: string, p: string) {
  if (p.startsWith("/") || /^[A-Za-z]:[\\/]/.test(p)) return p;
  const rel = p.replace(/^\.\//, "");
  return rel === "." || rel === "" ? base : `${base.replace(/\/$/, "")}/${rel}`;
}

/** Last path segment: jdtls names a Java project after the folder it imported. */
function baseName(p: string): string {
  const s = p.replace(/[\\/]+$/, "");
  const cut = Math.max(s.lastIndexOf("/"), s.lastIndexOf("\\"));
  return cut >= 0 ? s.slice(cut + 1) : s;
}
/** The name jdtls knows this folder's Java project by: Eclipse's project descriptor for an Eclipse
 * project, the Maven artifactId for a module (jdtls names those after the artifact, not the
 * folder), and the folder name when neither says anything.
 */
export async function javaProjectName(root: string): Promise<string> {
  const descriptor = await readText(join(root, ".project"));
  const eclipse = /<name>([^<]+)<\/name>/.exec(descriptor)?.[1]?.trim();
  if (eclipse) return eclipse;
  const pom = await readText(join(root, "pom.xml"));
  // A child module's own <artifactId> follows the <parent> block, which names the parent.
  const own = pom.replace(/<parent>[\s\S]*?<\/parent>/, "");
  const artifact = /<artifactId>\s*([^<\s]+)\s*<\/artifactId>/.exec(own)?.[1];
  if (artifact && !artifact.includes("${")) return artifact;
  return baseName(root);
}

/** A file of the project, or "" when it is missing (or when there is no filesystem bridge). */
async function readText(path: string): Promise<string> {
  try {
    return await call(commands.fsReadText(path));
  } catch {
    return "";
  }
}

/** Conventional JVM source sets, including Kotlin kept in a Java source directory.
 * A mixed module uses Kotlin's adapter, which also accepts Java line breakpoints.
 */
export async function moduleHasKotlinSources(cwd: string): Promise<boolean> {
  const pending = [join(cwd, "src")];
  while (pending.length) {
    const path = pending.pop()!;
    const entries = await call(commands.fsReadDir(path)).catch(() => []);
    for (const entry of entries) {
      if (entry.excluded) continue;
      if ((entry.kind === "file" || entry.targetKind === "file") && entry.name.endsWith(".kt")) return true;
      // Do not follow directory symlinks: a source tree can link back to a parent.
      if (entry.kind === "dir") pending.push(entry.path);
    }
  }
  return false;
}

/** java-debug missing from jdtls: offer the one-click install (jdtls restarts with the bundle). */
function offerInstall(e: unknown): never {
  if (e instanceof IpcError && e.kind === "unavailable" && /java-debug|debugger/i.test(e.message)) {
    notifications().notify({
      group: "run",
      level: "warning",
      key: "debug.java-debug-missing",
      title: "The Java debugger is not installed",
      body: "Debugging Java needs Microsoft java-debug, loaded into the Java language server. Install it and debug again once jdtls has restarted.",
      sticky: true,
      actions: [{ label: "Install", run: () => void executeAction("tools.install", JAVA_ADAPTER) }],
    });
  }
  throw e;
}

async function debugServer(module: string, signal?: AbortSignal): Promise<number> {
  try {
    return await call(commands.javaDebugServer(module));
  } catch (e) {
    signal?.throwIfAborted();
    offerInstall(e);
  }
}

/** Launch request for an Application configuration (`java … -cp ${classpath} Main args`). */
export async function javaLaunchConfig(
  rc: RunConfig,
  root: string,
  preparation?: JavaPreparation,
): Promise<LaunchConfig> {
  const cwd = rc.cwd ? join(root, rc.cwd) : root;
  const parsed = parseJavaArgs(rc.args);
  if (!parsed.mainClass) throw new Error(`No main class in '${rc.name}'`);
  preparation?.signal.throwIfAborted();
  const { module, info, resolved } = await prepareJavaLaunch(
    rc,
    preparation ?? {
      request: nextRequestId(),
      signal: new AbortController().signal,
    },
  );
  if (info.errorCount > 0 && !preparation?.report)
    notifications().notify({
      group: "run",
      level: "warning",
      key: "debug.java-compile-errors",
      title: `'${rc.name}' has compile errors; debugging the last compiled classes`,
      body: formatCompileErrors(info).trimEnd(),
    });
  const kotlin = rc.debugAdapter === KOTLIN_ADAPTER || (await moduleHasKotlinSources(join(root, module)));
  preparation?.signal.throwIfAborted();
  const classPaths = parsed.explicitClasspath
    ? parsed.explicitClasspath.split(info.pathListSeparator)
    : info.classPaths;
  if (kotlin) {
    return {
      name: rc.name,
      adapter: KOTLIN_ADAPTER,
      request: "launch",
      program: null,
      args: [],
      cwd,
      env: { ...rc.env },
      extraJson: JSON.stringify({
        projectRoot: join(root, module),
        mainClass: parsed.mainClass,
        classPaths,
        modulePaths: info.modulePaths,
        javaExec: resolved.command,
        vmArguments: [...consoleVmArgs(rc), ...parsed.vmArgs],
        programArgs: parsed.programArgs,
      }),
    };
  }
  const port = await debugServer(module, preparation?.signal);
  preparation?.signal.throwIfAborted();
  // java-debug resolves the Java project for Evaluate on its own from `mainClass` only when
  // the class belongs to a project it knows; name the project it imported so that works for
  // classes compiled outside the language server's build (plain folders, custom outputs).
  const project = await javaProjectName(info.projectRoot ?? root);
  return {
    name: rc.name,
    adapter: JAVA_ADAPTER,
    request: "launch",
    program: null,
    // java-debug takes `args` / `vmArgs` as strings.
    args: [],
    cwd,
    env: { ...rc.env },
    extraJson: JSON.stringify({
      debugServer: port,
      mainClass: parsed.mainClass,
      classPaths,
      modulePaths: info.modulePaths,
      projectName: project,
      javaExec: resolved.command === "java" ? undefined : resolved.command,
      vmArgs: joinJavaArgs([...consoleVmArgs(rc), ...parsed.vmArgs]),
      args: joinJavaArgs(parsed.programArgs),
      // java-debug spawns the JVM itself: it must shorten a classpath too long for the OS the same way Run does.
      shortenCommandLine: info.shortenCommandLine ?? "none",
      console: "internalConsole",
      stopOnEntry: false,
    }),
  };
}

export interface JavaAttachTarget {
  name: string;
  /** Module directory (relative to the project root) whose jdtls resolves sources. */
  module: string;
  hostName: string;
  port: number;
}

export function isJavaAttachTarget(
  arg: unknown,
): arg is JavaAttachTarget & { process?: number | null; runConfig?: RunConfig } {
  return !!arg && typeof arg === "object" && "port" in arg && typeof (arg as { port: unknown }).port === "number";
}

/** Attach request for a JVM listening with a JDWP agent. */
export async function javaAttachConfig(target: JavaAttachTarget, root: string): Promise<LaunchConfig> {
  const cwd = target.module ? join(root, target.module) : root;
  if (await moduleHasKotlinSources(cwd)) {
    return {
      name: target.name,
      adapter: KOTLIN_ADAPTER,
      request: "attach",
      program: null,
      args: [],
      cwd,
      env: {},
      extraJson: JSON.stringify({ projectRoot: cwd, hostName: target.hostName, port: target.port, timeout: 30_000 }),
    };
  }
  const port = await debugServer(target.module);
  // java-debug resolves the Java project for Evaluate from `mainClass` only when the class is in
  // a project it imported; a JDWP attach cannot even see the main class, so name the project the
  // language server imported (the directory name of the module it opened).
  const project = await javaProjectName(cwd);
  return {
    name: target.name,
    adapter: JAVA_ADAPTER,
    request: "attach",
    program: null,
    args: [],
    cwd: target.module ? join(root, target.module) : root,
    env: {},
    extraJson: JSON.stringify({
      debugServer: port,
      hostName: target.hostName,
      port: target.port,
      timeout: 30_000,
      projectName: project,
    }),
  };
}