import streamlit as st
import importlib
from io import BytesIO
import docx
from PyPDF2 import PdfReader

st.set_page_config(page_title="Multilingual Translator", page_icon="🌐", layout="centered")

# Import LANGUAGES from translation.py
try:
    from translation import LANGUAGES
except ImportError as e:
    st.error(f"Failed to import translation module: {e}")
    st.stop()

# Function to extract text from uploaded files (PDF, DOCX, TXT)
def extract_text_from_file(uploaded_file):
    try:
        if uploaded_file.type == "application/pdf":
            pdf_reader = PdfReader(uploaded_file)
            text = ""
            for page in pdf_reader.pages:
                text += page.extract_text() or ""
            return text.encode().decode('utf-8', errors='ignore').strip()
        elif uploaded_file.type == "application/vnd.openxmlformats-officedocument.wordprocessingml.document":
            doc = docx.Document(uploaded_file)
            text = "\n".join([para.text for para in doc.paragraphs])
            return text.encode().decode('utf-8', errors='ignore').strip()
        elif uploaded_file.type == "text/plain":
            return uploaded_file.read().decode('utf-8', errors='ignore').strip()
        return ""
    except Exception:
        return ""

# Callback to update input text when file is uploaded
def on_file_upload():
    uploaded_file = st.session_state.file_input
    if uploaded_file and uploaded_file.size < 1024*1024:
        st.session_state.user_input_text = extract_text_from_file(uploaded_file)
    elif uploaded_file and uploaded_file.size >= 1024*1024:
        st.error("File size must be less than 1 MB")

# Main application function
def main():
    try:
        translation_module = importlib.import_module("translation")
        language_detector = importlib.import_module("lang_detect")
        audio_processor_module = importlib.import_module("audio_processor")

        # Header
        st.markdown("<h1 style='text-align: center; color: #4285F4;'>Multilingual Translator</h1>", unsafe_allow_html=True)
        st.markdown("<p style='text-align: center; color: #666;'>Effortless Multilingual Translation</p>", unsafe_allow_html=True)

        # Custom CSS to hide size limit and show only file types
        st.markdown(
            """
            <style>
            .stFileUploader > div > div > div[role="button"] {
                display: none !important;
            }
            .stFileUploader label {
                display: block !important;
                color: #666 !important;
                font-size: 0.8em !important;
            }
            .stFileUploader label::after {
                content: 'TXT, DOCX, PDF' !important;
            }
            </style>
            """,
            unsafe_allow_html=True
        )

        # Language and Input/Output Layout with symmetric columns
        left_col, right_col = st.columns([1, 1])  # Equal width for symmetric layout
        with left_col:
            detected_options = language_detector.detect_language(st.session_state.get("user_input_text", "")) if st.session_state.get("user_input_text", "").strip() else [("Auto-detect", 1.0, "Auto-detect")]
            source_language = detected_options[0][2] if detected_options[0][0] != "Auto-detect" else "Auto-detect"
            source_lang_code = next((k for k, v in LANGUAGES.items() if v[1] == source_language), "hi") if source_language != "Auto-detect" else "auto"
            source_options = ["Auto-detect"] + [f"{v[0]} ({v[1]})" for v in LANGUAGES.values()]
            st.selectbox("Source Language", options=source_options, index=0 if source_language == "Auto-detect" else source_options.index(f"{LANGUAGES[source_lang_code][0]} ({source_language})"), key="source_lang")
            user_input_text = st.text_area("Input Text", height=400, key="user_input_text", placeholder="Enter text here", label_visibility="hidden")
            input_type = st.radio("Input Type", ["Text", "File"], horizontal=True, label_visibility="hidden", key="input_type")
            if input_type == "File":
                st.file_uploader("Upload File", type=["txt", "docx", "pdf"], key="file_input", on_change=on_file_upload, label_visibility="hidden")
                if st.session_state.get("file_input") and st.session_state.get("file_input").size >= 1024*1024:
                    st.error("File size must be less than 1 MB")
            st.button("Translate", key="translate_btn", on_click=trigger_translation, args=(translation_module, language_detector, audio_processor_module))
        with right_col:
            source_lang_display = st.session_state.source_lang.split(" (")[0] if " (" in st.session_state.source_lang else st.session_state.source_lang
            target_options = [f"{v[0]} ({v[1]})" for v in LANGUAGES.values() if v[0] != source_lang_display and v[1] != source_lang_display]
            st.selectbox("Target Language", options=target_options, index=target_options.index(f"{LANGUAGES['en'][0]} ({LANGUAGES['en'][1]})") if "English" not in source_lang_display else 0, key="target_lang")
            if "translated_text" in st.session_state:
                st.text_area("Output Text", value=st.session_state.translated_text, height=400, key="output_text", disabled=True, label_visibility="hidden")
                # Play audio button and playback below output
                if st.button("🔊", key="audio_btn", on_click=play_audio, args=(audio_processor_module,), help="Play audio", use_container_width=False):
                    pass
        # Footer
        if "translated_text" in st.session_state:
            st.markdown("""
                <p style="font-size: small; color: grey; text-align: center;">
                    Developed By: Krishna Prakash
                    <a href="https://www.linkedin.com/in/krishnaprakash-profile/" target="_blank">
                        <img src="https://img.icons8.com/ios-filled/30/0077b5/linkedin.png" alt="LinkedIn" style="vertical-align: middle; margin: 0 5px;"/>
                    </a>
                </p>
            """, unsafe_allow_html=True)

    except Exception as e:
        st.error(f"App error: {e}")

# Function to trigger translation process with progress indicator
def trigger_translation(translation_module, language_detector, audio_processor_module):
    user_input_text = st.session_state.get("user_input_text", "").strip()
    if user_input_text:
        with st.spinner("Translating..."):
            source_lang = st.session_state.source_lang.split(" (")[0] if " (" in st.session_state.source_lang else st.session_state.source_lang
            target_lang = st.session_state.target_lang.split(" (")[0] if " (" in st.session_state.target_lang else st.session_state.target_lang
            if source_lang == "Auto-detect":
                detected_options = language_detector.detect_language(user_input_text)
                source_lang_code = next((k for k, v in LANGUAGES.items() if v[1] == detected_options[0][0]), "hi")
            else:
                source_lang_code = next((k for k, v in LANGUAGES.items() if v[0] == source_lang), "hi")
            target_lang_code = next((k for k, v in LANGUAGES.items() if v[0] == target_lang), "en")
            translated_text = translation_module.translate(user_input_text, source_lang_code, target_lang_code)
            st.session_state.translated_text = translated_text or user_input_text

# Function to handle audio playback
def play_audio(audio_processor_module):
    if "translated_text" in st.session_state and st.session_state.translated_text:
        target_lang = next((k for k, v in LANGUAGES.items() if v[0] == st.session_state.target_lang.split(" (")[0]), "en")
        audio_data = audio_processor_module.text_to_speech(st.session_state.translated_text, target_lang)
        if audio_data and audio_data.getbuffer().nbytes > 0:
            st.audio(audio_data, format="audio/mp3")

if __name__ == "__main__":
    main()