#!/usr/bin/env python3
"""Agent for analyzing API Gateway access logs for security threats."""

import re
import json
import argparse
from datetime import datetime

import pandas as pd


def load_api_logs(log_path):
    """Load API gateway logs from JSON lines or CSV."""
    if log_path.endswith(".csv"):
        return pd.read_csv(log_path, parse_dates=["timestamp"])
    return pd.read_json(log_path, lines=True)


def detect_bola_attacks(df, threshold=50):
    """Detect Broken Object Level Authorization (BOLA/IDOR) attacks."""
    findings = []
    if "resource_id" not in df.columns:
        path_col = "request_path" if "request_path" in df.columns else "path"
        df["resource_id"] = df[path_col].str.extract(r'/(\d+)(?:/|$|\?)')
    df_with_ids = df.dropna(subset=["resource_id"])
    if df_with_ids.empty:
        return findings
    user_col = "user_id" if "user_id" in df.columns else "source_ip"
    grouped = df_with_ids.groupby([user_col]).agg(
        unique_resources=("resource_id", "nunique"),
        total_requests=("resource_id", "count"),
    ).reset_index()
    bola_suspects = grouped[grouped["unique_resources"] >= threshold]
    for _, row in bola_suspects.iterrows():
        findings.append({
            "user": row[user_col],
            "unique_resources_accessed": int(row["unique_resources"]),
            "total_requests": int(row["total_requests"]),
            "type": "BOLA/IDOR",
            "severity": "CRITICAL",
        })
    return findings


def detect_auth_scanning(df, threshold=100):
    """Detect credential scanning via 401/403 response surges."""
    findings = []
    auth_failures = df[df["status_code"].isin([401, 403])]
    if auth_failures.empty:
        return findings
    ip_col = "source_ip" if "source_ip" in df.columns else "client_ip"
    ip_failures = auth_failures.groupby(ip_col).agg(
        failure_count=("status_code", "count"),
        unique_endpoints=("request_path", "nunique") if "request_path" in df.columns
        else ("path", "nunique"),
    ).reset_index()
    scanners = ip_failures[ip_failures["failure_count"] >= threshold]
    for _, row in scanners.iterrows():
        findings.append({
            "source_ip": row[ip_col],
            "auth_failures": int(row["failure_count"]),
            "endpoints_probed": int(row["unique_endpoints"]),
            "type": "credential_scanning",
            "severity": "HIGH",
        })
    return findings


def detect_injection_attempts(df):
    """Detect SQL/NoSQL injection attempts in request parameters."""
    injection_patterns = [
        r"(?:union\s+select|select\s+.*\s+from|drop\s+table|insert\s+into)",
        r"(?:'\s*or\s+'1'\s*=\s*'1|'\s*or\s+1\s*=\s*1)",
        r'(?:\$ne|\$gt|\$lt|\$regex|\$where)',
        r'(?:<script|javascript:|onerror=|onload=)',
        r'(?:\.\./\.\./|/etc/passwd|/proc/self)',
    ]
    findings = []
    path_col = "request_path" if "request_path" in df.columns else "path"
    query_col = "query_string" if "query_string" in df.columns else path_col
    for _, row in df.iterrows():
        request_str = str(row.get(query_col, "")) + str(row.get("request_body", ""))
        for pattern in injection_patterns:
            if re.search(pattern, request_str, re.IGNORECASE):
                findings.append({
                    "source_ip": row.get("source_ip", row.get("client_ip", "")),
                    "path": row.get(path_col, ""),
                    "pattern_matched": pattern,
                    "type": "injection_attempt",
                    "severity": "HIGH",
                })
                break
    return findings[:500]


def detect_rate_limit_bypass(df, window="1min", threshold=100):
    """Detect rate limit bypass attempts."""
    findings = []
    ip_col = "source_ip" if "source_ip" in df.columns else "client_ip"
    df_copy = df.copy()
    df_copy["timestamp"] = pd.to_datetime(df_copy["timestamp"])
    df_copy = df_copy.set_index("timestamp")
    for ip, group in df_copy.groupby(ip_col):
        resampled = group.resample(window).size()
        bursts = resampled[resampled > threshold]
        if len(bursts) > 0:
            findings.append({
                "source_ip": ip,
                "max_requests_per_min": int(resampled.max()),
                "burst_periods": len(bursts),
                "type": "rate_limit_bypass",
                "severity": "MEDIUM",
            })
    return sorted(findings, key=lambda x: x["max_requests_per_min"], reverse=True)[:50]


def detect_unusual_methods(df):
    """Detect unusual HTTP methods on typically read-only endpoints."""
    findings = []
    dangerous_methods = {"DELETE", "PUT", "PATCH"}
    method_col = "method" if "method" in df.columns else "http_method"
    path_col = "request_path" if "request_path" in df.columns else "path"
    unusual = df[df[method_col].str.upper().isin(dangerous_methods)]
    for _, row in unusual.iterrows():
        findings.append({
            "source_ip": row.get("source_ip", row.get("client_ip", "")),
            "method": row[method_col],
            "path": row[path_col],
            "status_code": int(row.get("status_code", 0)),
            "type": "unusual_method",
            "severity": "MEDIUM",
        })
    return findings[:200]


def main():
    parser = argparse.ArgumentParser(description="API Gateway Log Analysis Agent")
    parser.add_argument("--log-file", required=True, help="API gateway log file")
    parser.add_argument("--output", default="api_gateway_report.json")
    parser.add_argument("--action", choices=[
        "bola", "auth_scan", "injection", "rate_limit", "full_analysis"
    ], default="full_analysis")
    args = parser.parse_args()

    df = load_api_logs(args.log_file)
    report = {"generated_at": datetime.utcnow().isoformat(), "total_requests": len(df),
              "findings": {}}
    print(f"[+] Loaded {len(df)} API requests")

    if args.action in ("bola", "full_analysis"):
        findings = detect_bola_attacks(df)
        report["findings"]["bola"] = findings
        print(f"[+] BOLA suspects: {len(findings)}")

    if args.action in ("auth_scan", "full_analysis"):
        findings = detect_auth_scanning(df)
        report["findings"]["auth_scanning"] = findings
        print(f"[+] Auth scanners: {len(findings)}")

    if args.action in ("injection", "full_analysis"):
        findings = detect_injection_attempts(df)
        report["findings"]["injection_attempts"] = findings
        print(f"[+] Injection attempts: {len(findings)}")

    if args.action in ("rate_limit", "full_analysis"):
        findings = detect_rate_limit_bypass(df)
        report["findings"]["rate_limit_bypass"] = findings
        print(f"[+] Rate limit bypasses: {len(findings)}")

    with open(args.output, "w") as f:
        json.dump(report, f, indent=2, default=str)
    print(f"[+] Report saved to {args.output}")


if __name__ == "__main__":
    main()