add missing constants

src/tools/ast-grep/constants.ts

@@ -1,5 +1,65 @@
-// ast-grep CLI path (homebrew installed)
-export const SG_CLI_PATH = "sg"
+import { createRequire } from "module"
+import { dirname, join } from "path"
+import { existsSync } from "fs"
+
+type Platform = "darwin" | "linux" | "win32" | "unsupported"
+
+function getPlatformPackageName(): string | null {
+  const platform = process.platform as Platform
+  const arch = process.arch
+
+  const platformMap: Record<string, string> = {
+    "darwin-arm64": "@ast-grep/cli-darwin-arm64",
+    "darwin-x64": "@ast-grep/cli-darwin-x64",
+    "linux-arm64": "@ast-grep/cli-linux-arm64-gnu",
+    "linux-x64": "@ast-grep/cli-linux-x64-gnu",
+    "win32-x64": "@ast-grep/cli-win32-x64-msvc",
+    "win32-arm64": "@ast-grep/cli-win32-arm64-msvc",
+    "win32-ia32": "@ast-grep/cli-win32-ia32-msvc",
+  }
+
+  return platformMap[`${platform}-${arch}`] ?? null
+}
+
+function findSgCliPath(): string {
+  // 1. Try to find from @ast-grep/cli package (installed via npm)
+  try {
+    const require = createRequire(import.meta.url)
+    const cliPkgPath = require.resolve("@ast-grep/cli/package.json")
+    const cliDir = dirname(cliPkgPath)
+    const sgPath = join(cliDir, process.platform === "win32" ? "sg.exe" : "sg")
+
+    if (existsSync(sgPath)) {
+      return sgPath
+    }
+  } catch {
+    // @ast-grep/cli not installed, try platform-specific package
+  }
+
+  // 2. Try platform-specific package directly
+  const platformPkg = getPlatformPackageName()
+  if (platformPkg) {
+    try {
+      const require = createRequire(import.meta.url)
+      const pkgPath = require.resolve(`${platformPkg}/package.json`)
+      const pkgDir = dirname(pkgPath)
+      const binaryName = process.platform === "win32" ? "ast-grep.exe" : "ast-grep"
+      const binaryPath = join(pkgDir, binaryName)
+
+      if (existsSync(binaryPath)) {
+        return binaryPath
+      }
+    } catch {
+      // Platform-specific package not installed
+    }
+  }
+
+  // 3. Fallback to system PATH
+  return "sg"
+}
+
+// ast-grep CLI path (auto-detected from node_modules or system PATH)
+export const SG_CLI_PATH = findSgCliPath()
 
 // CLI supported languages (25 total)
 export const CLI_LANGUAGES = [