write docs

Author: David Sheldrick

README.md

@@ -4,11 +4,97 @@ Obfuscate selected source files when building react-native bundles.
 
 ## Usage
 
-TODO
+### /rn-cli.config.js
+
+```diff
+ module.exports = {
++  getTransformModulePath() {
++    return require.resolve("./transformer")
++  },
+ }
+```
+
+### /transformer.js
+
+```js
+const obfuscatingTransformer = require("react-native-obfuscating-transformer")
+
+module.exports = obfuscatingTransformer({
+  /* options */
+})
+```
 
 ## Configuration
 
-TODO
+Options are:
+
+### `upstreamTransformer: MetroTransformer`
+
+Defines what the first pass of code transformation is. If you don't use a custom transformer already,
+you don't need to set this option.
+
+TypeScript example:
+
+```diff
+ const obfuscatingTransformer = require('react-native-obfuscating-transformer')
++ const typescriptTransformer = require('react-native-typescript-transformer')
+
+ module.exports = obfuscatingTransformer({
++  upstreamTransformer: typescriptTransformer
+ })
+```
+
+#### Default value: `require('metro/src/transformer')`
+
+### `filter: (filename: string, source: string) => boolean`
+
+Returns true for any files that should be obfuscated and false for any files which should not be obfuscated.
+
+By default, it obfuscates all files in `src/**/*`
+
+### `obfuscatorOptions: ObfuscatorOptions`
+
+**Warning** — Not all options are guaranteed to produce working code. In particular, `stringArray` definitely breaks builds.
+
+See the [javascript-obfuscator docs](https://github.com/javascript-obfuscator/javascript-obfuscator) for more info about what each option does.
+
+```ts
+interface ObfuscatorOptions {
+  compact?: boolean
+  controlFlowFlattening?: boolean
+  controlFlowFlatteningThreshold?: 0.75
+  deadCodeInjection?: boolean
+  deadCodeInjectionThreshold?: 0.4
+  debugProtection?: boolean
+  debugProtectionInterval?: boolean
+  disableConsoleOutput?: boolean
+  domainLock?: string[]
+  identifierNamesGenerator?: "hexadecimal" | "mangled"
+  log?: boolean
+  renameGlobals?: boolean
+  reservedNames?: string[]
+  rotateStringArray?: true
+  seed?: 0
+  selfDefending?: boolean
+  sourceMap?: boolean
+  sourceMapBaseUrl?: string
+  sourceMapFileName?: string
+  sourceMapMode?: "separate" | "inline"
+  stringArray?: boolean
+  stringArrayEncoding?: boolean
+  stringArrayThreshold?: 0.75
+  target?: "browser" | "extension" | "node"
+  unicodeEscapeSequence?: boolean
+}
+```
+
+### `trace: boolean`
+
+Iff true, prints a list of files being obfuscated
+
+### `emitObfuscatedFiles: boolean`
+
+Iff true, emits the obfuscated versions of files alongside their originals, for comparison.
 
 ## License