import fs from "node:fs";
import path from "node:path";
import type { ExecAllowlistEntry } from "./exec-approvals.js";
import { resolveDispatchWrapperExecutionPlan } from "./exec-wrapper-resolution.js";
import { expandHomePrefix } from "./home-dir.js";

export const DEFAULT_SAFE_BINS = ["jq", "cut", "uniq", "head", "tail", "tr", "wc"];

export type CommandResolution = {
  rawExecutable: string;
  resolvedPath?: string;
  resolvedRealPath?: string;
  executableName: string;
  effectiveArgv?: string[];
  wrapperChain?: string[];
  policyBlocked?: boolean;
  blockedWrapper?: string;
};

function isExecutableFile(filePath: string): boolean {
  try {
    const stat = fs.statSync(filePath);
    if (!stat.isFile()) {
      return false;
    }
    if (process.platform !== "win32") {
      fs.accessSync(filePath, fs.constants.X_OK);
    }
    return true;
  } catch {
    return false;
  }
}

function parseFirstToken(command: string): string | null {
  const trimmed = command.trim();
  if (!trimmed) {
    return null;
  }
  const first = trimmed[0];
  if (first === '"' || first === "'") {
    const end = trimmed.indexOf(first, 1);
    if (end > 1) {
      return trimmed.slice(1, end);
    }
    return trimmed.slice(1);
  }
  const match = /^[^\s]+/.exec(trimmed);
  return match ? match[0] : null;
}

function resolveExecutablePath(rawExecutable: string, cwd?: string, env?: NodeJS.ProcessEnv) {
  const expanded = rawExecutable.startsWith("~") ? expandHomePrefix(rawExecutable) : rawExecutable;
  if (expanded.includes("/") || expanded.includes("\\")) {
    if (path.isAbsolute(expanded)) {
      return isExecutableFile(expanded) ? expanded : undefined;
    }
    const base = cwd && cwd.trim() ? cwd.trim() : process.cwd();
    const candidate = path.resolve(base, expanded);
    return isExecutableFile(candidate) ? candidate : undefined;
  }
  const envPath = env?.PATH ?? env?.Path ?? process.env.PATH ?? process.env.Path ?? "";
  const entries = envPath.split(path.delimiter).filter(Boolean);
  const hasExtension = process.platform === "win32" && path.extname(expanded).length > 0;
  const extensions =
    process.platform === "win32"
      ? hasExtension
        ? [""]
        : (
            env?.PATHEXT ??
            env?.Pathext ??
            process.env.PATHEXT ??
            process.env.Pathext ??
            ".EXE;.CMD;.BAT;.COM"
          )
            .split(";")
            .map((ext) => ext.toLowerCase())
      : [""];
  for (const entry of entries) {
    for (const ext of extensions) {
      const candidate = path.join(entry, expanded + ext);
      if (isExecutableFile(candidate)) {
        return candidate;
      }
    }
  }
  return undefined;
}

function tryResolveRealpath(filePath: string | undefined): string | undefined {
  if (!filePath) {
    return undefined;
  }
  try {
    return fs.realpathSync(filePath);
  } catch {
    return undefined;
  }
}

export function resolveCommandResolution(
  command: string,
  cwd?: string,
  env?: NodeJS.ProcessEnv,
): CommandResolution | null {
  const rawExecutable = parseFirstToken(command);
  if (!rawExecutable) {
    return null;
  }
  const resolvedPath = resolveExecutablePath(rawExecutable, cwd, env);
  const resolvedRealPath = tryResolveRealpath(resolvedPath);
  const executableName = resolvedPath ? path.basename(resolvedPath) : rawExecutable;
  return {
    rawExecutable,
    resolvedPath,
    resolvedRealPath,
    executableName,
    effectiveArgv: [rawExecutable],
    wrapperChain: [],
    policyBlocked: false,
  };
}

export function resolveCommandResolutionFromArgv(
  argv: string[],
  cwd?: string,
  env?: NodeJS.ProcessEnv,
): CommandResolution | null {
  const plan = resolveDispatchWrapperExecutionPlan(argv);
  const effectiveArgv = plan.argv;
  const rawExecutable = effectiveArgv[0]?.trim();
  if (!rawExecutable) {
    return null;
  }
  const resolvedPath = resolveExecutablePath(rawExecutable, cwd, env);
  const resolvedRealPath = tryResolveRealpath(resolvedPath);
  const executableName = resolvedPath ? path.basename(resolvedPath) : rawExecutable;
  return {
    rawExecutable,
    resolvedPath,
    resolvedRealPath,
    executableName,
    effectiveArgv,
    wrapperChain: plan.wrappers,
    policyBlocked: plan.policyBlocked,
    blockedWrapper: plan.blockedWrapper,
  };
}

function normalizeMatchTarget(value: string): string {
  if (process.platform === "win32") {
    const stripped = value.replace(/^\\\\[?.]\\/, "");
    return stripped.replace(/\\/g, "/").toLowerCase();
  }
  return value.replace(/\\\\/g, "/").toLowerCase();
}

function tryRealpath(value: string): string | null {
  try {
    return fs.realpathSync(value);
  } catch {
    return null;
  }
}

function globToRegExp(pattern: string): RegExp {
  let regex = "^";
  let i = 0;
  while (i < pattern.length) {
    const ch = pattern[i];
    if (ch === "*") {
      const next = pattern[i + 1];
      if (next === "*") {
        regex += ".*";
        i += 2;
        continue;
      }
      regex += "[^/]*";
      i += 1;
      continue;
    }
    if (ch === "?") {
      regex += ".";
      i += 1;
      continue;
    }
    regex += ch.replace(/[.*+?^${}()|[\\]\\\\]/g, "\\$&");
    i += 1;
  }
  regex += "$";
  return new RegExp(regex, "i");
}

function matchesPattern(pattern: string, target: string): boolean {
  const trimmed = pattern.trim();
  if (!trimmed) {
    return false;
  }
  const expanded = trimmed.startsWith("~") ? expandHomePrefix(trimmed) : trimmed;
  const hasWildcard = /[*?]/.test(expanded);
  let normalizedPattern = expanded;
  let normalizedTarget = target;
  if (process.platform === "win32" && !hasWildcard) {
    normalizedPattern = tryRealpath(expanded) ?? expanded;
    normalizedTarget = tryRealpath(target) ?? target;
  }
  normalizedPattern = normalizeMatchTarget(normalizedPattern);
  normalizedTarget = normalizeMatchTarget(normalizedTarget);
  const regex = globToRegExp(normalizedPattern);
  return regex.test(normalizedTarget);
}

export function resolveAllowlistCandidatePath(
  resolution: CommandResolution | null,
  cwd?: string,
): string | undefined {
  if (!resolution) {
    return undefined;
  }
  if (resolution.resolvedPath) {
    return resolution.resolvedPath;
  }
  const raw = resolution.rawExecutable?.trim();
  if (!raw) {
    return undefined;
  }
  const expanded = raw.startsWith("~") ? expandHomePrefix(raw) : raw;
  if (!expanded.includes("/") && !expanded.includes("\\")) {
    return undefined;
  }
  if (path.isAbsolute(expanded)) {
    return expanded;
  }
  const base = cwd && cwd.trim() ? cwd.trim() : process.cwd();
  return path.resolve(base, expanded);
}

export function matchAllowlist(
  entries: ExecAllowlistEntry[],
  resolution: CommandResolution | null,
): ExecAllowlistEntry | null {
  if (!entries.length) {
    return null;
  }
  // A bare "*" wildcard allows any parsed executable command.
  // Check it before the resolvedPath guard so unresolved PATH lookups still
  // match (for example platform-specific executables without known extensions).
  const bareWild = entries.find((e) => e.pattern?.trim() === "*");
  if (bareWild && resolution) {
    return bareWild;
  }
  if (!resolution?.resolvedPath) {
    return null;
  }
  const resolvedPath = resolution.resolvedPath;
  for (const entry of entries) {
    const pattern = entry.pattern?.trim();
    if (!pattern) {
      continue;
    }
    const hasPath = pattern.includes("/") || pattern.includes("\\") || pattern.includes("~");
    if (!hasPath) {
      continue;
    }
    if (matchesPattern(pattern, resolvedPath)) {
      return entry;
    }
  }
  return null;
}

export type ExecArgvToken =
  | {
      kind: "empty";
      raw: string;
    }
  | {
      kind: "terminator";
      raw: string;
    }
  | {
      kind: "stdin";
      raw: string;
    }
  | {
      kind: "positional";
      raw: string;
    }
  | {
      kind: "option";
      raw: string;
      style: "long";
      flag: string;
      inlineValue?: string;
    }
  | {
      kind: "option";
      raw: string;
      style: "short-cluster";
      cluster: string;
      flags: string[];
    };

/**
 * Tokenizes a single argv entry into a normalized option/positional model.
 * Consumers can share this model to keep argv parsing behavior consistent.
 */
export function parseExecArgvToken(raw: string): ExecArgvToken {
  if (!raw) {
    return { kind: "empty", raw };
  }
  if (raw === "--") {
    return { kind: "terminator", raw };
  }
  if (raw === "-") {
    return { kind: "stdin", raw };
  }
  if (!raw.startsWith("-")) {
    return { kind: "positional", raw };
  }
  if (raw.startsWith("--")) {
    const eqIndex = raw.indexOf("=");
    if (eqIndex > 0) {
      return {
        kind: "option",
        raw,
        style: "long",
        flag: raw.slice(0, eqIndex),
        inlineValue: raw.slice(eqIndex + 1),
      };
    }
    return { kind: "option", raw, style: "long", flag: raw };
  }
  const cluster = raw.slice(1);
  return {
    kind: "option",
    raw,
    style: "short-cluster",
    cluster,
    flags: cluster.split("").map((entry) => `-${entry}`),
  };
}
