import gradio as gr
from PIL import Image, ImageOps
import requests
import io
import json
import logging
import os
import struct
import tempfile
from cryptography.hazmat.primitives import serialization
from cryptography.hazmat.primitives.asymmetric import rsa, padding
from cryptography.hazmat.primitives.ciphers.aead import AESGCM
from cryptography.hazmat.primitives import hashes
import numpy as np

logging.basicConfig(level=logging.INFO, format='%(asctime)s - %(name)s - %(levelname)s - %(message)s')

# --- Backend Logic Class ---
class AppServerLogic:
    """Contains all backend logic and mock data needed by the application."""
    def __init__(self):
        self.private_key_object = None
        self.public_key_pem = ""
        self.mock_user_db = {
            "demo-user": {"api_key": "sk-12345-abcde", "password": "password123"},
            "admin-user": {"api_key": "sk-67890-fghij", "password": "adminpass"}
        }
        self._initialize_keys()

    def _initialize_keys(self):
        key_pem = os.environ.get('KEYLOCK_PRIV_KEY')
        if not key_pem:
            pk = rsa.generate_private_key(public_exponent=65537, key_size=2048)
            key_pem = pk.private_bytes(encoding=serialization.Encoding.PEM, format=serialization.PrivateFormat.PKCS8, encryption_algorithm=serialization.NoEncryption()).decode('utf-8')
        try:
            self.private_key_object = serialization.load_pem_private_key(key_pem.encode(), password=None)
            self.public_key_pem = self.private_key_object.public_key().public_bytes(encoding=serialization.Encoding.PEM, format=serialization.PublicFormat.SubjectPublicKeyInfo).decode('utf-8')
        except Exception as e:
            logging.error(f"Key initialization failed: {e}")

    def decode_payload(self, image_input):
        if not self.private_key_object:
            return {"status": "Error", "message": "Server key not configured."}
        try:
            pixel_data = np.array(image_input.convert("RGB")).ravel()
            header_binary = "".join(str(p & 1) for p in pixel_data[:32])
            data_length = int(header_binary, 2)
            required_pixels = 32 + data_length * 8
            if required_pixels > len(pixel_data):
                raise ValueError("Incomplete payload in image.")
            data_binary = "".join(str(p & 1) for p in pixel_data[32:required_pixels])
            crypto_payload = int(data_binary, 2).to_bytes(data_length, byteorder='big')
            offset = 4
            encrypted_aes_key_len = struct.unpack('>I', crypto_payload[:offset])[0]
            encrypted_aes_key = crypto_payload[offset:offset + encrypted_aes_key_len]; offset += encrypted_aes_key_len
            nonce = crypto_payload[offset:offset + 12]; offset += 12
            ciphertext = crypto_payload[offset:]
            recovered_aes_key = self.private_key_object.decrypt(encrypted_aes_key, padding.OAEP(mgf=padding.MGF1(hashes.SHA256()), algorithm=hashes.SHA256(), label=None))
            payload = json.loads(AESGCM(recovered_aes_key).decrypt(nonce, ciphertext, None).decode())
            return {"status": "Success", "payload": payload}
        except Exception as e:
            return {"status": "Error", "message": f"Decryption Failed: {e}"}
            
    def generate_encrypted_image(self, payload_dict):
        """Creates a KeyLock image and returns its filepath for both preview and download."""
        try:
            response = requests.get("https://images.unsplash.com/photo-1506318137071-a8e063b4bec0?q=80&w=1200", timeout=10)
            img = ImageOps.fit(Image.open(io.BytesIO(response.content)).convert("RGB"), (600, 600))
        except:
            img = Image.new('RGB', (600, 600), color=(15, 23, 42))
        
        json_bytes = json.dumps(payload_dict).encode('utf-8')
        public_key = serialization.load_pem_public_key(self.public_key_pem.encode('utf-8'))
        aes_key, nonce = os.urandom(32), os.urandom(12)
        ciphertext = AESGCM(aes_key).encrypt(nonce, json_bytes, None)
        rsa_key = public_key.encrypt(aes_key, padding.OAEP(mgf=padding.MGF1(hashes.SHA256()), algorithm=hashes.SHA256(), label=None))
        payload = struct.pack('>I', len(rsa_key)) + rsa_key + nonce + ciphertext
        
        pixel_data = np.array(img).ravel()
        binary_payload = ''.join(format(b, '08b') for b in struct.pack('>I', len(payload)) + payload)
        pixel_data[:len(binary_payload)] = (pixel_data[:len(binary_payload)] & 0xFE) | np.array(list(binary_payload), dtype=np.uint8)
        final_image = Image.fromarray(pixel_data.reshape(img.size[1], img.size[0], 3), 'RGB')
        
        with tempfile.NamedTemporaryFile(suffix=".png", delete=False) as f:
            final_image.save(f.name, "PNG")
            # Return the filepath for both the preview image and the download file.
            return f.name, f.name

    @staticmethod
    def generate_pem_keys():
        pk = rsa.generate_private_key(public_exponent=65537, key_size=2048)
        priv = pk.private_bytes(encoding=serialization.Encoding.PEM, format=serialization.PrivateFormat.PKCS8, encryption_algorithm=serialization.NoEncryption()).decode()
        pub = pk.public_key().public_bytes(encoding=serialization.Encoding.PEM, format=serialization.PublicFormat.SubjectPublicKeyInfo).decode()
        return priv, pub

# --- UI Component Class ---
class KeylockDecoderComponent(gr.components.Component):
    """A Gradio Component that decodes a KeyLock image and provides advanced tools."""
    EVENTS = ["change"]

    def __init__(self, server_logic, **kwargs):
        self.server_logic = server_logic
        self.value = None 
        super().__init__(**kwargs)

    def _format_message(self, result: dict | None) -> str:
        if not result or not result.get("status"): return "Upload a KeyLock image to auto-fill credentials."
        status = result["status"]
        if status == "Success":
            user = result.get("payload", {}).get("USER", "N/A")
            return f"<p style='color:green; font-weight:bold;'>✅ Success! Decoded credentials for '{user}'.</p>"
        else:
            message = result.get("message", "An unknown error occurred.")
            return f"<p style='color:red; font-weight:bold;'>❌ Error: {message}</p>"

    def preprocess(self, payload): return payload
    def postprocess(self, value): return value
    def api_info(self): return {"type": "object", "example": {"status": "Success", "payload": {"USER": "demo-user"}}}

    def render(self):
        value_state = gr.State(value=self.value)
        
        with gr.Column():
            image_input = gr.Image(label="KeyLock Image", type="pil", show_label=False)
            status_display = gr.Markdown(self._format_message(self.value))

            with gr.Accordion("Generate Encrypted Image", open=False):
                gr.Markdown("Create a test image using the site's public key.")
                payload_input = gr.JSON(label="Payload to Encrypt", value={"API_KEY": "sk-12345-abcde", "USER": "demo-user"})
                generate_img_button = gr.Button("Generate Image", variant="secondary")
                # This component now expects a filepath to display the uncorrupted PNG.
                generated_image_preview = gr.Image(label="Generated Image Preview", type="filepath", interactive=False)
                generated_file_download = gr.File(label="Download Uncorrupted PNG", interactive=False)
            
            with gr.Accordion("Create New Standalone Key Pair", open=False):
                gr.Markdown("Generate a new, random key pair for testing or other uses.")
                generate_keys_button = gr.Button("Generate Keys", variant="secondary")
                with gr.Row():
                    output_private_key = gr.Code(label="Generated Private Key", language="python")
                    output_public_key = gr.Code(label="Generated Public Key", language="python")

        def on_image_upload(image):
            if image is None: return None, "Upload a KeyLock image to auto-fill credentials."
            result_dict = self.server_logic.decode_payload(image)
            formatted_message = self._format_message(result_dict)
            return result_dict, formatted_message

        image_input.upload(fn=on_image_upload, inputs=[image_input], outputs=[value_state, status_display])
        generate_img_button.click(
            fn=self.server_logic.generate_encrypted_image,
            inputs=[payload_input],
            outputs=[generated_image_preview, generated_file_download]
        )
        generate_keys_button.click(fn=self.server_logic.generate_pem_keys, inputs=None, outputs=[output_private_key, output_public_key])
        
        return {"value": value_state}