/**
 * Terminal-capability detection: enumerates known terminal tool names, detects
 * whether a usable terminal/shell exists in the environment, resolves the shell
 * and executables to run, and reports the missing tool for a given command.
 */
import fs from "node:fs";
import path from "node:path";

export const TERMINAL_TOOL_NAMES = [
  "sh",
  "git",
  "rg",
  "bun",
  "acpx",
  "codex",
  "claude",
  "opencode",
] as const;

export type TerminalToolName = (typeof TERMINAL_TOOL_NAMES)[number];

export interface ToolCapability {
  name: TerminalToolName;
  path?: string;
  available: boolean;
}

export interface ShellResolution {
  shell: string;
  args: string[];
  available: boolean;
  source: "env:CODING_TOOLS_SHELL" | "env:SHELL" | "candidate" | "fallback";
  warning?: string;
}

export type TerminalUnsupportedReason =
  | "store_build"
  | "vanilla_mobile"
  | "not_local_yolo"
  | "missing_shell";

export interface TerminalSupport {
  supported: boolean;
  reason?: TerminalUnsupportedReason;
  message?: string;
}

const ANDROID_PATH_ENTRIES = ["/system/bin", "/system/xbin", "/vendor/bin"];

export function isAndroidRuntime(): boolean {
  return (
    process.env.ELIZA_PLATFORM?.trim().toLowerCase() === "android" ||
    Boolean(process.env.ANDROID_ROOT || process.env.ANDROID_DATA)
  );
}

function isIosRuntime(): boolean {
  return process.env.ELIZA_PLATFORM?.trim().toLowerCase() === "ios";
}

function isTruthyEnv(value: string | undefined): boolean {
  if (!value) return false;
  return ["1", "true", "yes", "on"].includes(value.trim().toLowerCase());
}

function isStoreBuild(): boolean {
  const variant = process.env.ELIZA_BUILD_VARIANT ?? "";
  return variant.trim().toLowerCase() === "store";
}

function runtimeMode(): string {
  return (
    process.env.ELIZA_RUNTIME_MODE ??
    process.env.RUNTIME_MODE ??
    process.env.LOCAL_RUNTIME_MODE ??
    ""
  )
    .trim()
    .toLowerCase();
}

export function isAospTerminalRuntime(): boolean {
  return isAndroidRuntime() && isTruthyEnv(process.env.ELIZA_AOSP_BUILD);
}

function executableExists(candidate: string): boolean {
  try {
    fs.accessSync(candidate, fs.constants.X_OK);
    return true;
  } catch {
    // error-policy:J3 existence/permission probe; access failure means the
    // candidate is absent or not executable — false is the expected miss.
    return false;
  }
}

function pathEntries(): string[] {
  const entries = (process.env.PATH ?? "")
    .split(path.delimiter)
    .map((entry) => entry.trim())
    .filter(Boolean);
  if (isAndroidRuntime()) {
    for (const entry of ANDROID_PATH_ENTRIES) {
      if (!entries.includes(entry)) entries.push(entry);
    }
  }
  return entries;
}

export function resolveExecutable(nameOrPath: string): string | undefined {
  const trimmed = nameOrPath.trim();
  if (!trimmed) return undefined;
  if (trimmed.includes("/") || path.isAbsolute(trimmed)) {
    return executableExists(trimmed) ? trimmed : undefined;
  }
  for (const entry of pathEntries()) {
    const candidate = path.join(entry, trimmed);
    if (executableExists(candidate)) return candidate;
  }
  return undefined;
}

function firstExecutable(candidates: readonly string[]): string | undefined {
  for (const candidate of candidates) {
    const resolved = resolveExecutable(candidate);
    if (resolved) return resolved;
  }
  return undefined;
}

export function resolveTerminalShell(): ShellResolution {
  const explicitEntries = [
    ["CODING_TOOLS_SHELL", process.env.CODING_TOOLS_SHELL] as const,
    ["SHELL", process.env.SHELL] as const,
  ];
  for (const [key, raw] of explicitEntries) {
    const value = raw?.trim();
    if (!value) continue;
    const resolved = resolveExecutable(value);
    if (resolved) {
      return {
        shell: resolved,
        args: ["-c"],
        available: true,
        source: key === "CODING_TOOLS_SHELL" ? "env:CODING_TOOLS_SHELL" : "env:SHELL",
      };
    }
  }

  const candidates = isAndroidRuntime()
    ? ["/system/bin/sh", "sh"]
    : ["/bin/bash", "bash", "/bin/sh", "sh"];
  const shell = firstExecutable(candidates);
  if (shell) {
    return {
      shell,
      args: ["-c"],
      available: true,
      source: "candidate",
    };
  }

  return {
    shell: isAndroidRuntime() ? "/system/bin/sh" : "sh",
    args: ["-c"],
    available: false,
    source: "fallback",
    warning: isAndroidRuntime()
      ? "No executable POSIX shell was detected. Android direct/AOSP local-yolo builds must expose /system/bin/sh or set CODING_TOOLS_SHELL to an executable shell."
      : "No executable POSIX shell was detected. Set SHELL or CODING_TOOLS_SHELL to an executable shell.",
  };
}

export function detectTerminalCapabilities(): ToolCapability[] {
  return TERMINAL_TOOL_NAMES.map((name) => {
    if (name === "sh") {
      const shell = resolveTerminalShell();
      return {
        name,
        path: shell.available ? shell.shell : undefined,
        available: shell.available,
      };
    }
    const resolved = resolveExecutable(name);
    return {
      name,
      path: resolved,
      available: Boolean(resolved),
    };
  });
}

export function formatTerminalCapabilities(capabilities = detectTerminalCapabilities()): string {
  return capabilities
    .map((capability) =>
      capability.available
        ? `${capability.name}=ok(${capability.path})`
        : `${capability.name}=missing`
    )
    .join(" ");
}

export function missingToolMessage(tool: TerminalToolName): string {
  if (tool === "sh") {
    return resolveTerminalShell().warning ?? "No executable shell was detected.";
  }
  const suffix = isAndroidRuntime()
    ? " On Android direct/AOSP builds, ensure the binary is staged into the agent image and PATH includes /system/bin or the tool's install directory."
    : " Install it or add it to PATH.";
  return `${tool} CLI is not available in PATH.${suffix}`;
}

export function missingTerminalToolForCommand(command: string): TerminalToolName | undefined {
  const tokens = command.trim().split(/\s+/).filter(Boolean);
  let index = 0;
  while (tokens[index] && /^[A-Za-z_][A-Za-z0-9_]*=/.test(tokens[index])) {
    index += 1;
  }
  const first = tokens[index]?.replace(/^["']|["']$/g, "");
  if (!first) return undefined;
  const name = path.basename(first) as TerminalToolName;
  if (!(TERMINAL_TOOL_NAMES as readonly string[]).includes(name) || name === "sh") {
    return undefined;
  }
  return resolveExecutable(first) ? undefined : name;
}

export function detectTerminalSupport(): TerminalSupport {
  if (isStoreBuild()) {
    return {
      supported: false,
      reason: "store_build",
      message:
        "Local terminal execution is unavailable in store builds because the OS sandbox blocks spawning local shells and developer CLIs.",
    };
  }

  if (isIosRuntime()) {
    return {
      supported: false,
      reason: "vanilla_mobile",
      message:
        "Local terminal execution is unavailable on iOS because the runtime does not expose shell, coding, or orchestrator subprocess capabilities.",
    };
  }

  if (isAndroidRuntime()) {
    if (runtimeMode() !== "local-yolo") {
      return {
        supported: false,
        reason: "not_local_yolo",
        message:
          "Android direct/AOSP terminal execution requires ELIZA_RUNTIME_MODE=local-yolo so commands run in the local agent environment.",
      };
    }
    const shell = resolveTerminalShell();
    if (!shell.available) {
      return {
        supported: false,
        reason: "missing_shell",
        message:
          shell.warning ??
          "Android direct/AOSP terminal execution requires an executable shell. Set CODING_TOOLS_SHELL or SHELL to a staged shell binary.",
      };
    }
  }

  return { supported: true };
}