"""
Neo4j Graph Visualizer - A beautiful, high-performance graph visualization app.

Connects to Neo4j, executes Cypher queries, precomputes layouts in Python,
and renders stunning visualizations in the browser.
"""

import os
import json
import hashlib
import colorsys
import logging
import time
import base64
from collections import defaultdict
from urllib.parse import urlparse

import requests as http_requests
from flask import Flask, render_template, jsonify, request

from layout_engine import compute_layout, get_available_algorithms

# ---------------------------------------------------------------------------
# Configuration
# ---------------------------------------------------------------------------
logging.basicConfig(
    level=logging.INFO, format="%(asctime)s [%(levelname)s] %(message)s"
)
logger = logging.getLogger(__name__)

app = Flask(__name__)

# Neo4j HTTP API endpoint (not Bolt)
NEO4J_HTTP_URL = os.environ.get("NEO4J_HTTP_URL", "http://localhost")
NEO4J_USER = os.environ.get("NEO4J_USER", "neo4j")
NEO4J_PASSWORD = os.environ.get("NEO4J_PASSWORD", "")
NEO4J_DATABASE = os.environ.get("NEO4J_DATABASE", "neo4j")


# ---------------------------------------------------------------------------
# Neo4j HTTP Transactional API helpers
# ---------------------------------------------------------------------------
def _neo4j_auth_header():
    """Build Basic auth header for Neo4j HTTP API."""
    cred = f"{NEO4J_USER}:{NEO4J_PASSWORD}"
    b64 = base64.b64encode(cred.encode()).decode()
    return {
        "Authorization": f"Basic {b64}",
        "Content-Type": "application/json",
        "Accept": "application/json;charset=UTF-8",
    }


def _neo4j_tx_url(database=None):
    """Build the transactional commit endpoint URL."""
    db = database or NEO4J_DATABASE
    base = NEO4J_HTTP_URL.rstrip("/")
    return f"{base}/db/{db}/tx/commit"


def execute_cypher(cypher: str, params: dict | None = None):
    """
    Execute a Cypher query via the Neo4j HTTP Transactional API.
    Returns (nodes_dict, edges_list, records_list, keys).
    """
    url = _neo4j_tx_url()
    headers = _neo4j_auth_header()
    payload = {
        "statements": [
            {
                "statement": cypher,
                "parameters": params or {},
                "resultDataContents": ["row", "graph"],
            }
        ]
    }

    resp = http_requests.post(url, json=payload, headers=headers, timeout=120)
    resp.raise_for_status()
    body = resp.json()

    # Check for Neo4j-level errors
    if body.get("errors"):
        err_msgs = "; ".join(e.get("message", str(e)) for e in body["errors"])
        raise RuntimeError(err_msgs)

    nodes: dict = {}
    edges: list = []
    seen_edges: set = set()
    records_out: list = []
    keys: list = []

    for result in body.get("results", []):
        keys = result.get("columns", [])

        for datum in result.get("data", []):
            # --- Extract row data for table view ---
            row_data = datum.get("row", [])
            row = {}
            for i, key in enumerate(keys):
                row[key] = row_data[i] if i < len(row_data) else None
            records_out.append(row)

            # --- Extract graph data for visualization ---
            graph_data = datum.get("graph", {})

            for node_data in graph_data.get("nodes", []):
                nid = str(node_data["id"])
                if nid not in nodes:
                    labels = node_data.get("labels", [])
                    props = node_data.get("properties", {})
                    display = (
                        props.get("name")
                        or props.get("title")
                        or props.get("id")
                        or props.get("sku")
                        or (labels[0] if labels else nid)
                    )
                    nodes[nid] = {
                        "id": nid,
                        "labels": labels,
                        "properties": props,
                        "label": str(display)[:80],
                    }

            for rel_data in graph_data.get("relationships", []):
                eid = str(rel_data["id"])
                if eid not in seen_edges:
                    seen_edges.add(eid)
                    edges.append(
                        {
                            "id": eid,
                            "source": str(rel_data["startNode"]),
                            "target": str(rel_data["endNode"]),
                            "type": rel_data.get("type", "RELATED"),
                            "properties": rel_data.get("properties", {}),
                        }
                    )

    return nodes, edges, records_out, keys


def _execute_simple(cypher: str):
    """Execute a simple Cypher query and return rows."""
    url = _neo4j_tx_url()
    headers = _neo4j_auth_header()
    payload = {"statements": [{"statement": cypher}]}
    resp = http_requests.post(url, json=payload, headers=headers, timeout=30)
    resp.raise_for_status()
    body = resp.json()
    if body.get("errors"):
        err_msgs = "; ".join(e.get("message", str(e)) for e in body["errors"])
        raise RuntimeError(err_msgs)
    rows = []
    for result in body.get("results", []):
        for datum in result.get("data", []):
            rows.append(datum.get("row", []))
    return rows


# ---------------------------------------------------------------------------
# Color generation
# ---------------------------------------------------------------------------
_PALETTE = [
    "#00d4ff",
    "#ff6b6b",
    "#ffd93d",
    "#6bcb77",
    "#9b59b6",
    "#e67e22",
    "#1abc9c",
    "#e74c3c",
    "#3498db",
    "#f39c12",
    "#2ecc71",
    "#e91e63",
    "#00bcd4",
    "#ff9800",
    "#8bc34a",
    "#673ab7",
    "#009688",
    "#ff5722",
    "#607d8b",
    "#cddc39",
]


def color_for_label(label: str) -> str:
    """Return a vivid, consistent color for a label string."""
    idx = int(hashlib.md5(label.encode()).hexdigest()[:8], 16)
    return _PALETTE[idx % len(_PALETTE)]


# ---------------------------------------------------------------------------
# Routes
# ---------------------------------------------------------------------------
@app.route("/")
def index():
    return render_template("index.html")


@app.route("/api/query", methods=["POST"])
def api_query():
    data = request.get_json(force=True)
    cypher = data.get("query", "").strip()
    layout_algo = data.get("layout", "auto")
    spacing = float(data.get("spacing", 1.0))
    iterations = int(data.get("iterations", 300))

    if not cypher:
        return jsonify({"error": "Empty query"}), 400

    try:
        t0 = time.time()
        nodes_dict, edges, records, keys = execute_cypher(cypher)
        t_query = time.time() - t0

        # Assign colours
        label_colors: dict[str, str] = {}
        for nd in nodes_dict.values():
            for lb in nd.get("labels", []):
                if lb not in label_colors:
                    label_colors[lb] = color_for_label(lb)

        # Compute layout server-side
        t1 = time.time()
        positions = compute_layout(
            nodes_dict,
            edges,
            algorithm=layout_algo,
            spacing=spacing,
            iterations=iterations,
        )
        t_layout = time.time() - t1

        # Degree for sizing
        degree: dict[str, int] = defaultdict(int)
        for e in edges:
            degree[e["source"]] += 1
            degree[e["target"]] += 1
        max_deg = max(degree.values()) if degree else 1

        nodes_list = []
        for nid, nd in nodes_dict.items():
            pos = positions.get(nid, {"x": 0, "y": 0})
            primary = nd["labels"][0] if nd.get("labels") else "Unknown"
            nd["x"] = pos["x"]
            nd["y"] = pos["y"]
            nd["color"] = label_colors.get(primary, "#888888")
            d = degree.get(nid, 0)
            nd["size"] = 3 + (d / max(max_deg, 1)) * 22
            nodes_list.append(nd)

        # Deduplicate edges (keep unique source-target-type combos)
        seen = set()
        unique_edges = []
        for e in edges:
            key = (e["source"], e["target"], e["type"])
            if key not in seen:
                seen.add(key)
                unique_edges.append(e)

        return jsonify(
            {
                "nodes": nodes_list,
                "edges": unique_edges,
                "label_colors": label_colors,
                "records": records[:500],  # cap tabular results
                "keys": keys,
                "stats": {
                    "node_count": len(nodes_list),
                    "edge_count": len(unique_edges),
                    "labels": list(label_colors.keys()),
                    "query_time_ms": round(t_query * 1000),
                    "layout_time_ms": round(t_layout * 1000),
                },
            }
        )
    except Exception as exc:
        logger.exception("Query failed")
        return jsonify({"error": str(exc)}), 400


@app.route("/api/schema")
def api_schema():
    try:
        labels = [r[0] for r in _execute_simple("CALL db.labels()")]
        rel_types = [r[0] for r in _execute_simple("CALL db.relationshipTypes()")]
        prop_keys = [r[0] for r in _execute_simple("CALL db.propertyKeys()")]
        return jsonify(
            {
                "labels": labels,
                "relationship_types": rel_types,
                "property_keys": prop_keys,
            }
        )
    except Exception as exc:
        return jsonify({"error": str(exc)}), 400


@app.route("/api/connection-test")
def api_connection_test():
    try:
        rows = _execute_simple("RETURN 1 AS ok")
        if rows and rows[0][0] == 1:
            return jsonify({"status": "connected", "uri": NEO4J_HTTP_URL})
        raise RuntimeError("Unexpected response")
    except Exception as exc:
        return jsonify({"status": "error", "message": str(exc)}), 500


@app.route("/api/reconnect", methods=["POST"])
def api_reconnect():
    global NEO4J_HTTP_URL, NEO4J_USER, NEO4J_PASSWORD, NEO4J_DATABASE
    data = request.get_json(force=True)
    new_url = data.get("uri", "").strip()
    new_user = data.get("user", "").strip()
    new_pass = data.get("password", "")

    if not new_url:
        return jsonify({"status": "error", "message": "URL is required"}), 400

    NEO4J_HTTP_URL = new_url
    NEO4J_USER = new_user
    NEO4J_PASSWORD = new_pass

    try:
        rows = _execute_simple("RETURN 1 AS ok")
        if rows and rows[0][0] == 1:
            return jsonify({"status": "connected", "uri": NEO4J_HTTP_URL})
        raise RuntimeError("Unexpected response")
    except Exception as exc:
        return jsonify({"status": "error", "message": str(exc)}), 500


@app.route("/api/layouts")
def api_layouts():
    return jsonify(get_available_algorithms())


@app.route("/api/sample-queries")
def api_sample_queries():
    queries = [
        {
            "name": "Sample Graph (100)",
            "query": "MATCH (n)-[r]->(m) RETURN n, r, m LIMIT 100",
        },
        {
            "name": "Sample Graph (500)",
            "query": "MATCH (n)-[r]->(m) RETURN n, r, m LIMIT 500",
        },
        {
            "name": "Sample Graph (2000)",
            "query": "MATCH (n)-[r]->(m) RETURN n, r, m LIMIT 2000",
        },
        {
            "name": "Node Label Counts",
            "query": "MATCH (n) RETURN labels(n)[0] AS label, count(*) AS count ORDER BY count DESC LIMIT 25",
        },
        {
            "name": "Relationship Type Counts",
            "query": "MATCH ()-[r]->() RETURN type(r) AS type, count(*) AS count ORDER BY count DESC LIMIT 25",
        },
        {
            "name": "High-Connectivity Nodes",
            "query": "MATCH (n)-[r]-() WITH n, count(r) AS degree ORDER BY degree DESC LIMIT 20 MATCH (n)-[r2]->(m) RETURN n, r2, m LIMIT 300",
        },
        {
            "name": "Shortest Path (sample)",
            "query": "MATCH (a), (b) WHERE a <> b WITH a, b LIMIT 1 MATCH path = shortestPath((a)-[*..5]-(b)) RETURN path",
        },
        {
            "name": "Connected Component (depth 3)",
            "query": "MATCH (start) WITH start LIMIT 1 MATCH path = (start)-[*1..3]-(connected) RETURN path LIMIT 300",
        },
        {"name": "Schema Visualization", "query": "CALL db.schema.visualization()"},
    ]
    return jsonify(queries)


@app.route("/api/demo", methods=["POST"])
def api_demo():
    """Generate a demo graph for testing the visualization without Neo4j."""
    import random

    data = request.get_json(force=True) if request.is_json else {}
    size = min(int(data.get("size", 300)), 5000)
    layout_algo = data.get("layout", "auto")
    spacing = float(data.get("spacing", 1.0))
    iterations = int(data.get("iterations", 300))

    random.seed(42)

    label_types = [
        "Product",
        "Category",
        "Brand",
        "Supplier",
        "Attribute",
        "Color",
        "Material",
        "Tag",
        "Collection",
        "Review",
    ]
    rel_types = [
        "BELONGS_TO",
        "MADE_BY",
        "SUPPLIED_BY",
        "HAS_ATTRIBUTE",
        "HAS_COLOR",
        "MADE_OF",
        "TAGGED_WITH",
        "PART_OF",
        "REVIEWED_IN",
        "SIMILAR_TO",
    ]

    adj_names = [
        "Premium",
        "Eco",
        "Organic",
        "Classic",
        "Modern",
        "Vintage",
        "Smart",
        "Ultra",
        "Compact",
        "Deluxe",
    ]
    noun_names = [
        "Widget",
        "Gadget",
        "Module",
        "Unit",
        "Element",
        "Component",
        "System",
        "Kit",
        "Bundle",
        "Pack",
    ]

    nodes_dict = {}
    edges = []

    # assign label distribution (more products, fewer reviews)
    weights = [30, 15, 10, 8, 10, 5, 5, 7, 5, 5]

    for i in range(size):
        r = random.random() * sum(weights)
        cumulative = 0
        chosen_label = label_types[0]
        for idx, w in enumerate(weights):
            cumulative += w
            if r <= cumulative:
                chosen_label = label_types[idx]
                break

        name = f"{random.choice(adj_names)} {random.choice(noun_names)} {i}"
        nid = f"demo_{i}"
        nodes_dict[nid] = {
            "id": nid,
            "labels": [chosen_label],
            "properties": {
                "name": name,
                "sku": f"SKU-{i:05d}",
                "price": round(random.uniform(5, 500), 2),
            },
            "label": name,
        }

    # Create edges — mix of random & preferential attachment
    node_ids = list(nodes_dict.keys())
    edge_count = int(size * 1.5)
    degree = defaultdict(int)
    for _ in range(edge_count):
        src = random.choice(node_ids)
        # Preferential attachment: higher-degree nodes more likely as targets
        if random.random() < 0.3 and degree:
            top = sorted(degree, key=degree.get, reverse=True)[
                : max(1, len(top) if "top" in dir() else 10)
            ]
            tgt = random.choice(top)
        else:
            tgt = random.choice(node_ids)
        if src != tgt:
            edges.append(
                {
                    "id": f"edge_{len(edges)}",
                    "source": src,
                    "target": tgt,
                    "type": random.choice(rel_types),
                    "properties": {},
                }
            )
            degree[src] += 1
            degree[tgt] += 1

    # Color
    label_colors = {lt: color_for_label(lt) for lt in label_types}

    # Layout
    t1 = time.time()
    positions = compute_layout(
        nodes_dict, edges, algorithm=layout_algo, spacing=spacing, iterations=iterations
    )
    t_layout = time.time() - t1

    max_deg = max(degree.values()) if degree else 1
    nodes_list = []
    for nid, nd in nodes_dict.items():
        pos = positions.get(nid, {"x": 0, "y": 0})
        primary = nd["labels"][0]
        nd["x"] = pos["x"]
        nd["y"] = pos["y"]
        nd["color"] = label_colors.get(primary, "#888")
        d = degree.get(nid, 0)
        nd["size"] = 3 + (d / max(max_deg, 1)) * 22
        nodes_list.append(nd)

    return jsonify(
        {
            "nodes": nodes_list,
            "edges": edges,
            "label_colors": label_colors,
            "records": [],
            "keys": [],
            "stats": {
                "node_count": len(nodes_list),
                "edge_count": len(edges),
                "labels": list(label_colors.keys()),
                "query_time_ms": 0,
                "layout_time_ms": round(t_layout * 1000),
            },
        }
    )


# ---------------------------------------------------------------------------
if __name__ == "__main__":
    app.run(debug=True, host="0.0.0.0", port=5555)