package expo.modules.zkexpo

import expo.modules.kotlin.modules.Module
import expo.modules.kotlin.modules.ModuleDefinition
import java.io.File

class ZkExpoModule : Module() {
    companion object {
        init {
            System.loadLibrary("native_rust_lib")
        }
    }

    // addToCache now returns a String: empty = success, non-empty = error JSON
    external fun groth16ProveV2(a: String, b: String, c: String): String
    external fun groth16ProveV2Base64(a: String, b: String, c: String): String
    external fun addToCache(a: String, b: String, c: String): String
    external fun clearCache(): Unit

    override fun definition() = ModuleDefinition {
        Name("ZkExpo")

        AsyncFunction("groth16ProveV2") { a: String, b: String, c: String ->
            guardPath(a, "graph_path")
            guardPath(b, "zkey_path")
            val result = groth16ProveV2(a, b, c)
            throwIfError(result, "groth16ProveV2")
            result
        }

        AsyncFunction("groth16ProveV2Base64") { a: String, b: String, c: String ->
            val result = groth16ProveV2Base64(a, b, c)
            throwIfError(result, "groth16ProveV2Base64")
            result
        }

        AsyncFunction("addToCache") { a: String, b: String, c: String ->
            guardPath(b, "path1")
            guardPath(c, "path2")
            val error = addToCache(a, b, c) ?: ""
            if (error.isNotEmpty()) {
                throw Exception("[$a] $error")
            }
        }

        AsyncFunction("clearCache") { clearCache() }
    }

    private fun guardPath(path: String, label: String) {
        if (path.contains('%')) {
            throw Exception(
                "$label appears URL-encoded ('$path'). " +
                "Strip the 'file://' prefix and call Uri.decode() / decodeURIComponent() " +
                "before passing the path to zk-expo."
            )
        }
        if (!File(path).exists()) {
            throw Exception("File not found at $label: $path")
        }
    }

    private fun throwIfError(result: String, fn: String) {
        if (result.startsWith("{\"error\"")) {
            throw Exception("[$fn] $result")
        }
    }
}