//go:build js && wasm
// +build js,wasm

package main

import (
	"fmt"
	"syscall/js"
)

// verifySHA256 verifies that the SHA256 hash of the input data matches the provided expected hash.
func verifySHA256(this js.Value, args []js.Value) any {
	if len(args) < 2 {
		return js.ValueOf(map[string]any{
			"valid": false,
			"error": "invalid arguments: expected (data []uint8, expectedHash string)",
		})
	}

	dataLen := args[0].Get("length").Int()
	data := make([]byte, dataLen)
	
	steps := []any{}
	
	js.CopyBytesToGo(data, args[0])
	steps = append(steps, map[string]any{
		"name":    "Data Loading",
		"status":  "success",
		"details": fmt.Sprintf("Successfully read %d bytes into WASM memory", dataLen),
	})

	expectedHash := args[1].String()
	actualHash := computeSHA256(data)
	
	steps = append(steps, map[string]any{
		"name":    "Checksum Calculation",
		"status":  "success",
		"details": fmt.Sprintf("Computed SHA256: %s", actualHash),
	})

	if actualHash == expectedHash {
		steps = append(steps, map[string]any{
			"name":    "Identity Verification",
			"status":  "success",
			"details": "Computed hash matches the signed manifest",
		})
		return js.ValueOf(map[string]any{
			"valid": true,
			"steps": steps,
		})
	}

	steps = append(steps, map[string]any{
		"name":    "Identity Verification",
		"status":  "error",
		"details": fmt.Sprintf("Hash mismatch! Got %s, expected %s", actualHash, expectedHash),
	})
	
	return js.ValueOf(map[string]any{
		"valid": false,
		"steps": steps,
		"error": fmt.Sprintf("hash mismatch: got %s, expected %s", actualHash, expectedHash),
	})
}

// main initializes the WebAssembly module and exposes verifySHA256 to the JavaScript global scope.
func main() {
	c := make(chan struct{})
	fmt.Println("Software Verifier WASM Initialized")
	js.Global().Set("verifySHA256", js.FuncOf(verifySHA256))
	<-c
}