# streamlit_app.py
import streamlit as st
import pandas as pd
import numpy as np
from pathlib import Path
import uuid

from cards import (
    chat_card,
    inplace_chat_card
)

# ---------- Global state init ----------
if "init" not in st.session_state:
    st.session_state.init = True
    st.session_state.conversations = {}      # {chat_id: {"title": str, "messages": [...]}}
    st.session_state.current_chat_id = None  # which conversation is open

def create_new_conversation():
    chat_id = str(uuid.uuid4())
    st.session_state.conversations[chat_id] = {
        "title": "New chat",
        "messages": [],
        "editable": False,
        "prev_text": "",
        "edited_text": "",
        "original_user_prompt": "",
        "edit_history": []
    }
    st.session_state.current_chat_id = chat_id

# ensure at least one conversation exists
if not st.session_state.conversations:
    create_new_conversation()

# Fix code block font rendering - force monospace
st.markdown("""
<style>
code, pre, pre code {
    font-family: 'Space Mono', monospace !important;
    font-size: 0.95rem !important;
    line-height: 1.4 !important;
    font-weight: 400 !important;
}
</style>
""", unsafe_allow_html=True)

pages = [
    st.Page(
        "inplace_chat.py",
        title="In-place Feedback Chat",
        icon=":material/edit_document:"
    ),
    st.Page(
        "chat.py",
        title="Chat",
        icon=":material/chat:"
    )
]

page = st.navigation(pages)
# ---------- Sidebar: ChatGPT-style history ----------
with st.sidebar:
    # new chat button
    st.write("This is a simple demo for CSED499 Inplace feedback.")
    st.button(
        "＋ New chat",
        use_container_width=True,
        on_click=create_new_conversation,
    )
    st.markdown("---")
    st.markdown("### Chat History")

    # Add custom CSS for hover effect on chat history items
    st.markdown("""
        <style>
        /* Chat history item buttons */
        .stButton > button[kind="secondary"] {
            background-color: transparent;
            border: none;
            color: inherit;
            padding: 8px 12px;
            text-align: left;
            width: 100%;
            border-radius: 8px;
            transition: background-color 0.2s;
            justify-content: flex-start;
        }
        .stButton > button[kind="secondary"]:hover {
            background-color: rgba(128, 128, 128, 0.2);
        }
        .stButton > button[kind="secondary"]:focus {
            box-shadow: none;
        }
        /* Delete button styling */
        .stButton > button[kind="secondary"].delete-btn {
            width: auto;
            padding: 4px 8px;
            color: rgba(128, 128, 128, 0.6);
        }
        .stButton > button[kind="secondary"].delete-btn:hover {
            color: rgba(128, 128, 128, 1);
            background-color: rgba(128, 128, 128, 0.15);
        }
        </style>
    """, unsafe_allow_html=True)

    # list existing conversations as clickable text
    for chat_id, conv in st.session_state.conversations.items():
        # truncate title like ChatGPT
        label = conv["title"]
        if len(label) > 35:
            label = label[:35] + "…"

        # Create columns for chat item and delete button
        col_chat, col_delete = st.columns([0.85, 0.15])

        with col_chat:
            # highlight current chat with a marker
            if chat_id == st.session_state.current_chat_id:
                st.markdown(f"**▶ {label}**")
            else:
                # Make entire text clickable with hover effect
                if st.button(label, key=f"chat-{chat_id}", type="secondary", use_container_width=True):
                    st.session_state.current_chat_id = chat_id
                    st.rerun()

        with col_delete:
            # Delete button - only show for non-active chats or show for all
            if st.button("✕", key=f"delete-{chat_id}", type="secondary", help="Delete chat"):
                # If deleting current chat, switch to another one first
                if chat_id == st.session_state.current_chat_id:
                    remaining = [cid for cid in st.session_state.conversations.keys() if cid != chat_id]
                    if remaining:
                        st.session_state.current_chat_id = remaining[0]
                    else:
                        st.session_state.current_chat_id = None

                # Delete the conversation
                del st.session_state.conversations[chat_id]
                st.rerun()

# run selected page (after sidebar is defined)
page.run()


# === Edit History Panel ===
st.sidebar.markdown("### Edit History")

if st.session_state.current_chat_id:
    current_conv = st.session_state.conversations.get(st.session_state.current_chat_id, {})
    edit_history = current_conv.get("edit_history", [])

    if edit_history:
        st.sidebar.markdown("""
            <style>
            .diff-container {
                font-family: 'Space Mono', monospace;
                font-size: 0.85em;
                line-height: 1.4;
                margin: 8px 0;
                padding: 8px;
                background-color: rgba(128, 128, 128, 0.05);
                border-radius: 4px;
            }
            .diff-delete {
                background-color: rgba(255, 0, 0, 0.15);
                color: #d73a49;
                text-decoration: line-through;
                padding: 2px 4px;
                border-radius: 2px;
            }
            .diff-insert {
                background-color: rgba(0, 255, 0, 0.15);
                color: #22863a;
                padding: 2px 4px;
                border-radius: 2px;
            }
            .diff-equal {
                color: inherit;
            }
            </style>
        """, unsafe_allow_html=True)

        for idx, edit in enumerate(reversed(edit_history)):
            edit_num = len(edit_history) - idx
            # Each edit as a collapsible expander
            with st.sidebar.expander(f"Edit #{edit_num} at {edit['timestamp']}", expanded=False):
                # Build the diff HTML
                diff_html = "<div class='diff-container'>"
                for chunk in edit.get('diff_chunks', []):
                    text = chunk['text'].replace('<', '&lt;').replace('>', '&gt;')
                    if chunk['tag'] == 'delete':
                        diff_html += f"<span class='diff-delete'>{text}</span>"
                    elif chunk['tag'] == 'insert':
                        diff_html += f"<span class='diff-insert'>{text}</span>"
                    else:  # equal
                        # Truncate long unchanged sections
                        if len(text) > 100:
                            text = text[:50] + "..." + text[-50:]
                        diff_html += f"<span class='diff-equal'>{text}</span>"
                diff_html += "</div>"

                st.markdown(diff_html, unsafe_allow_html=True)
    else:
        st.sidebar.write("No edits yet in this conversation.")
else:
    st.sidebar.write("No conversation selected.")


# st.markdown("---")
st.sidebar.caption(
    "This app uses [Space Grotesk](https://fonts.google.com/specimen/Space+Grotesk) "
    "and [Space Mono](https://fonts.google.com/specimen/Space+Mono) fonts."
)