import streamlit as st
import os
import io
import requests
from lxml import etree
from converter import ModsConverter
from urllib.parse import quote, unquote

st.set_page_config(
    page_title="PubTypeConverter | DORA Tools",
    page_icon="🔄",
    layout="wide",
    initial_sidebar_state="collapsed"
)

# Custom CSS for a modern, premium look
st.markdown("""
<style>
    @import url('https://fonts.googleapis.com/css2?family=Inter:wght@400;600;700&display=swap');
    
    html, body, [class*="css"] {
        font-family: 'Inter', sans-serif;
    }
    
    .stApp {
        background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
    }
    
    /* Premium Header */
    .title-container {
        padding: 2rem 0;
        text-align: center;
        background: rgba(255, 255, 255, 0.4);
        backdrop-filter: blur(10px);
        border-radius: 20px;
        margin-bottom: 2rem;
        border: 1px solid rgba(255, 255, 255, 0.5);
        box-shadow: 0 8px 32px 0 rgba(31, 38, 135, 0.07);
    }
    
    .main-title {
        font-size: 3rem;
        font-weight: 700;
        background: linear-gradient(90deg, #1e3a8a, #3b82f6);
        -webkit-background-clip: text;
        -webkit-text-fill-color: transparent;
        margin-bottom: 0.5rem;
    }
    
    .sub-title {
        color: #64748b;
        font-size: 1.1rem;
    }
    
    /* Section Styling */
    .stSelectbox, .stTextInput, .stButton {
        margin-bottom: 1rem;
    }
    
    /* Card-like containers for results */
    .result-card {
        background: white;
        padding: 1.5rem;
        border-radius: 15px;
        box-shadow: 0 4px 6px -1px rgba(0, 0, 0, 0.1);
        margin-bottom: 1.5rem;
        border-left: 5px solid #3b82f6;
    }
    
    /* Step indicators */
    .step-header {
        font-weight: 600;
        color: #1e293b;
        margin-bottom: 1rem;
        display: flex;
        align-items: center;
        gap: 0.5rem;
    }
    
    .step-number {
        background: #3b82f6;
        color: white;
        width: 24px;
        height: 24px;
        border-radius: 50%;
        display: flex;
        align-items: center;
        justify-content: center;
        font-size: 0.8rem;
    }
</style>

<div class="title-container">
    <div class="main-title">DORA PubTypeConverter</div>
    <div class="sub-title">DORA Publication Type Transformation Helper</div>
</div>
""", unsafe_allow_html=True)

# Setup paths
BASE_DIR = os.path.dirname(os.path.abspath(__file__))
RESOURCE_DIR = os.path.join(BASE_DIR, "PubTypeConverter_resources")
TEMPLATE_DIR = os.path.join(RESOURCE_DIR, "PubTypeConverter_templates")
CONFIG_FILE = os.path.join(RESOURCE_DIR, "PubTypeConverterConfig.xml")

# Initialize Session State
if 'converter' not in st.session_state:
    converter = ModsConverter()
    if os.path.exists(CONFIG_FILE):
        converter.load_config(CONFIG_FILE)
    else:
        st.warning(f"Configuration file not found at {CONFIG_FILE}. Content moving rules will not be applied.")
    st.session_state.converter = converter

if 'loaded_files' not in st.session_state:
    st.session_state.loaded_files = [] # List of dicts: {'name': str, 'content': bytes}

# Load templates
templates = []
if os.path.exists(TEMPLATE_DIR):
    for f in os.listdir(TEMPLATE_DIR):
        if f.lower().endswith(".xml"):
            templates.append(f)
else:
    st.error(f"Template directory not found: {TEMPLATE_DIR}")
templates.sort()


# Helper function to fetch from DORA
def fetch_from_dora(pid_or_url, repo):
    url = pid_or_url.strip()
    
    # Handle double-encoded PIDs (e.g. psi%253A84411 -> psi%3A84411 -> psi:84411)
    # We unquote until the string stabilizes
    prev = None
    while url != prev:
        prev = url
        url = unquote(url)
    fallback_www = None
    fallback_oai = None
    
    if not url.startswith("http"):
        # Construct URL from PID
        # Assume PID format like "psi:12345" or just "12345"
        if ":" in url:
            parts = url.split(":")
            repo_prefix = parts[0].lower()
            # Force prefix to lowercase for repo mapping
            pid_val = f"{repo_prefix}:{parts[1]}"
            repo = repo_prefix 
        else:
             # Use selected repo
             pid_val = f"{repo}:{url}"
        
        # URL Encode the PID part - essential for Islandora
        quoted_pid = quote(pid_val)
        
        # Primary: Admin (Intranet, preferred)
        url = f"https://admin.dora.lib4ri.ch/{repo}/islandora/object/{quoted_pid}/datastream/MODS/view"
        
        # Fallback 1: WWW (Public mirror)
        fallback_www = f"https://www.dora.lib4ri.ch/{repo}/islandora/object/{quoted_pid}/datastream/MODS/view"
        
        # Fallback 2: OAI-PMH (Robust Public Access)
        # Use quoted PID for identifier to be safe (suggested by user example)
        fallback_oai = f"https://www.dora.lib4ri.ch/{repo}/oai2/request?verb=GetRecord&metadataPrefix=mods&identifier={quoted_pid}"

    headers = {'User-Agent': 'curl/7.68.0'}
    
    # helper to check OAI response for valid content
    def check_oai_response(content):
        try:
             root = etree.fromstring(content)
             
             # Check for OAI error code
             if root.xpath(".//*[local-name()='error']"):
                 return False
             
             # Ultimate robust search: find first 'mods' element regardless of namespace/prefix
             mods_nodes = root.xpath(".//*[local-name()='mods']")
             if mods_nodes:
                 return etree.tostring(mods_nodes[0], encoding='utf-8')
        except:
             pass
        return None

    try:
        # Try primary URL
        response = requests.get(url, headers=headers, timeout=10)
        response.raise_for_status()
        return response.content, url
    except Exception as e:
        status_errors = [f"Admin: {e}"]
        
        # Try Fallback 1: WWW
        if fallback_www:
            try:
                response = requests.get(fallback_www, headers=headers, timeout=10)
                response.raise_for_status()
                return response.content, fallback_www
            except Exception as e2:
                status_errors.append(f"WWW: {e2}")
        
        # Try Fallback 2: OAI-PMH
        if fallback_oai:
             try:
                response = requests.get(fallback_oai, headers=headers, timeout=10)
                if response.status_code == 200:
                    mods_content = check_oai_response(response.content)
                    if mods_content:
                        return mods_content, fallback_oai
                    else:
                        status_errors.append("OAI: Valid HTTP but no MODS found in response")
                else:
                    status_errors.append(f"OAI: HTTP {response.status_code}")
             except Exception as e3:
                status_errors.append(f"OAI: {e3}")

        return None, f"Failed to fetch. Details: {'; '.join(status_errors)}"

# UI Layout
main_col1, main_col2 = st.columns([0.6, 0.4], gap="large")

with main_col1:
    st.markdown('<div class="step-header"><div class="step-number">1</div><span>Select Source Data</span></div>', unsafe_allow_html=True)
    
    input_tab1, input_tab2 = st.tabs(["🌐 Pull from DORA", "📁 Upload Local XML"])
    
    with input_tab1:
        dora_col1, dora_col2 = st.columns([0.7, 0.3])
        dora_input = dora_col1.text_input("PID or URL", placeholder="e.g. psi:84411", label_visibility="collapsed")
        repo_select = dora_col2.selectbox("Repo", ["psi", "eawag", "empa", "wsl"], label_visibility="collapsed")
        
        if st.button("Fetch and Load Record", use_container_width=True):
            if dora_input:
                with st.spinner("Retrieving from DORA..."):
                    content, error_or_url = fetch_from_dora(dora_input, repo_select)
                    if content:
                        filename = dora_input.replace(":", "_").replace("/", "_") + ".xml"
                        if filename.startswith("http"): filename = "dora_record.xml"
                        st.session_state.loaded_files.append({"name": filename, "content": content, "source": error_or_url})
                        st.toast(f"Loaded {filename}", icon="✅")
                    else:
                        st.error(f"Fetch failed: {error_or_url}")
            else:
                st.warning("Please provide a identifier first.")

    with input_tab2:
        uploaded_files = st.file_uploader("Upload MODS XML files", type=['xml'], accept_multiple_files=True, label_visibility="collapsed")

    # Display loaded files in a modern list
    if st.session_state.loaded_files:
        st.markdown("### Loaded Documents")
        for i, file_data in enumerate(st.session_state.loaded_files):
            with st.container():
                f_col1, f_col2 = st.columns([0.85, 0.15])
                f_col1.markdown(f"📄 **{file_data['name']}**")
                if f_col2.button("🗑️", key=f"remove_{i}", help="Remove this file"):
                    st.session_state.loaded_files.pop(i)
                    st.rerun()

with main_col2:
    st.markdown('<div class="step-header"><div class="step-number">2</div><span>Target Format</span></div>', unsafe_allow_html=True)
    selected_template = st.selectbox("Choose the destination publication type", templates if templates else ["No templates found"], label_visibility="collapsed")
    
    st.markdown("---")
    if st.button("🚀 Start Conversion", disabled=not (uploaded_files or st.session_state.loaded_files) or not templates, use_container_width=True, type="primary"):
        st.session_state.start_convert = True
    else:
        st.session_state.start_convert = False

# Combine sources
all_files = []
if uploaded_files:
    for f in uploaded_files:
        all_files.append({"name": f.name, "content": f.getvalue()})
if st.session_state.loaded_files:
    all_files.extend(st.session_state.loaded_files)

if st.session_state.get("start_convert"):
    st.markdown('<div class="step-header"><div class="step-number">3</div><span>Conversion Reports</span></div>', unsafe_allow_html=True)
    
    for file_data in all_files:
        content = file_data['content']
        filename = file_data['name']
        
        # Try to decode if bytes, though lxml can parse bytes directly
        # But we pass string/bytes/path to converter
        
        template_path = os.path.join(TEMPLATE_DIR, selected_template)
        
        try:
            # result_xml is the XML string, log is the structured data dict
            result_xml, log_data = st.session_state.converter.convert(content, template_path)
            
            with st.container():
                st.markdown(f"""
                <div class="result-card">
                    <div style="display: flex; justify-content: space-between; align-items: center; margin-bottom: 1rem;">
                        <span style="font-weight: 700; font-size: 1.2rem; color: #1e3a8a;">{filename}</span>
                        <span style="background: #dbeafe; color: #1e40af; padding: 0.2rem 0.8rem; border-radius: 999px; font-size: 0.8rem; font-weight: 600;">TRANSFORMED</span>
                    </div>
                    <div style="display: flex; align-items: center; gap: 1rem; margin-bottom: 1.5rem;">
                         <span style="background: #f1f5f9; padding: 0.4rem 1rem; border-radius: 8px; font-size: 0.9rem; border: 1px solid #e2e8f0;">{log_data['old_genre']}</span>
                         <span style="color: #94a3b8;">➡️</span>
                         <span style="background: #ecfdf5; color: #065f46; padding: 0.4rem 1rem; border-radius: 8px; font-size: 0.9rem; border: 1px solid #d1fae5; font-weight: 600;">{log_data['new_genre']}</span>
                    </div>
                """, unsafe_allow_html=True)

                s_col1, s_col2, s_col3 = st.columns(3)
                s_col1.metric("Transfers", len(log_data["moves"]))
                s_col2.metric("Additions", len(log_data["additions"]))
                s_col3.metric("Removals", len(log_data["deletions"]))

                with st.expander("Audit Transformation Details", expanded=False):
                    if log_data["moves"]:
                        st.write("**🔄 Content Transfers**")
                        for m in log_data["moves"]:
                            st.caption(f"• {m['summary']}")
                    if log_data["additions"]:
                        st.write("**✨ Smart Additions**")
                        for a in log_data["additions"]:
                            st.caption(f"• {a['summary']}")
                    if log_data["deletions"]:
                        st.write("**🗑️ Legacy Cleanup**")
                        del_labels = [d['label'] for d in log_data["deletions"]]
                        st.caption(f"Removed {len(del_labels)} unused fields: " + ", ".join(del_labels[:8]) + ("..." if len(del_labels) > 8 else ""))

                if log_data["warnings"]:
                    for w in log_data["warnings"]:
                        st.warning(w)

                if result_xml:
                    st.download_button(
                        label=f"⬇️ Download {filename}",
                        data=result_xml,
                        file_name=f"{os.path.splitext(filename)[0]}_converted.xml",
                        mime="application/xml",
                        key=f"dl_{filename}",
                        use_container_width=True
                    )
                st.markdown('</div>', unsafe_allow_html=True)
        except Exception as e:
            st.error(f"Error converting {filename}: {e}")
            import traceback
            st.code(traceback.format_exc())