#!/usr/bin/env python3
"""
Ledger Receiver — runs on YOUR server to collect transaction records from remote gateways.

Each gateway POSTs transactions here. You keep an independent copy of every
transaction with hash verification. If the gateway operator resets their stats,
your ledger still has the full history.

Usage:
    python3 ledger_receiver.py
    LEDGER_SECRET=shared_secret python3 ledger_receiver.py

Endpoints:
    POST /transaction       — receive a transaction from a gateway
    GET  /ledger            — view all transactions
    GET  /reconcile/<host>  — compare your ledger against a gateway's
    GET  /summary           — total cost by gateway
"""

import json
import os
import hashlib
import threading
import time
from http.server import HTTPServer, BaseHTTPRequestHandler
from urllib.parse import urlparse

LISTEN_PORT = int(os.environ.get("RECEIVER_PORT", "8435"))
LEDGER_DIR = os.environ.get("LEDGER_DIR", "/var/lib/mortdecai-ledger")
LEDGER_SECRET = os.environ.get("LEDGER_SECRET", "change_me_shared_secret")

_lock = threading.Lock()


def _verify_hash(entry):
    raw = f"{entry['id']}|{entry['tokens_in']}|{entry['tokens_out']}|{entry['duration']}|{entry['cost']}|{LEDGER_SECRET}"
    expected = hashlib.sha256(raw.encode()).hexdigest()[:16]
    return entry.get("hash") == expected


def _save_transaction(entry, source_ip):
    """Save a transaction to the per-gateway ledger file."""
    entry["_received_at"] = time.strftime("%Y-%m-%dT%H:%M:%SZ")
    entry["_source_ip"] = source_ip
    entry["_hash_valid"] = _verify_hash(entry)

    os.makedirs(LEDGER_DIR, exist_ok=True)
    # One file per source IP
    safe_ip = source_ip.replace(":", "_").replace(".", "_")
    path = os.path.join(LEDGER_DIR, f"ledger_{safe_ip}.jsonl")

    with _lock:
        with open(path, "a") as f:
            f.write(json.dumps(entry) + "\n")


def _load_all():
    """Load all ledger entries from all gateways."""
    all_entries = {}
    try:
        for fname in os.listdir(LEDGER_DIR):
            if fname.endswith(".jsonl"):
                gateway = fname.replace("ledger_", "").replace(".jsonl", "")
                entries = []
                with open(os.path.join(LEDGER_DIR, fname)) as f:
                    for line in f:
                        if line.strip():
                            entries.append(json.loads(line))
                all_entries[gateway] = entries
    except:
        pass
    return all_entries


class ReceiverHandler(BaseHTTPRequestHandler):
    def log_message(self, fmt, *args):
        pass

    def _send_json(self, status, data):
        body = json.dumps(data, indent=2).encode()
        self.send_response(status)
        self.send_header("Content-Type", "application/json")
        self.end_headers()
        self.wfile.write(body)

    def do_POST(self):
        if self.path == "/transaction":
            length = int(self.headers.get("Content-Length", 0))
            entry = json.loads(self.rfile.read(length))
            source_ip = self.client_address[0]

            valid = _verify_hash(entry)
            _save_transaction(entry, source_ip)

            self._send_json(200, {
                "status": "recorded",
                "id": entry.get("id"),
                "hash_valid": valid,
            })
            return

        self._send_json(404, {"error": "not found"})

    def do_GET(self):
        parsed = urlparse(self.path)

        if parsed.path == "/summary":
            all_data = _load_all()
            summary = {}
            for gateway, entries in all_data.items():
                total_cost = sum(e.get("cost", 0) for e in entries)
                total_tokens = sum(e.get("tokens_out", 0) for e in entries)
                valid = sum(1 for e in entries if e.get("_hash_valid", False))
                invalid = len(entries) - valid
                summary[gateway] = {
                    "transactions": len(entries),
                    "total_cost": round(total_cost, 6),
                    "total_tokens_out": total_tokens,
                    "hashes_valid": valid,
                    "hashes_invalid": invalid,
                }
            self._send_json(200, summary)
            return

        if parsed.path == "/ledger":
            all_data = _load_all()
            flat = []
            for entries in all_data.values():
                flat.extend(entries)
            flat.sort(key=lambda e: e.get("timestamp", ""))

            total = sum(e.get("cost", 0) for e in flat)
            self._send_json(200, {
                "total_transactions": len(flat),
                "total_cost": round(total, 6),
                "last_20": flat[-20:],
            })
            return

        self._send_json(404, {"error": "not found"})


if __name__ == "__main__":
    os.makedirs(LEDGER_DIR, exist_ok=True)
    print(f"Ledger Receiver on port {LISTEN_PORT}")
    print(f"  Ledger dir: {LEDGER_DIR}")
    HTTPServer(("0.0.0.0", LISTEN_PORT), ReceiverHandler).serve_forever()