"""
FastAPI routes for System Screening (SBOM Generation + Vulnerability Scan).

Endpoints:
- POST /v1/screening/scan: Upload dependency file, generate SBOM, scan for vulnerabilities
- GET /v1/screening/{screening_id}: Get screening result by ID
- GET /v1/screening: List screenings for a tenant
"""

import json
import logging
import re
import uuid
from datetime import datetime, timezone
from typing import Optional

import httpx
from fastapi import APIRouter, File, Form, UploadFile, HTTPException
from pydantic import BaseModel
from sqlalchemy import text

from database import SessionLocal

logger = logging.getLogger(__name__)
router = APIRouter(prefix="/v1/screening", tags=["system-screening"])

OSV_API_URL = "https://api.osv.dev/v1/query"


# =============================================================================
# RESPONSE MODELS
# =============================================================================

class SecurityIssueResponse(BaseModel):
    id: str
    severity: str
    title: str
    description: Optional[str] = None
    cve: Optional[str] = None
    cvss: Optional[float] = None
    affected_component: str
    affected_version: Optional[str] = None
    fixed_in: Optional[str] = None
    remediation: Optional[str] = None
    status: str = "OPEN"


class SBOMComponentResponse(BaseModel):
    name: str
    version: str
    type: str
    purl: str
    licenses: list[str]
    vulnerabilities: list[dict]


class ScreeningResponse(BaseModel):
    id: str
    status: str
    sbom_format: str
    sbom_version: str
    total_components: int
    total_issues: int
    critical_issues: int
    high_issues: int
    medium_issues: int
    low_issues: int
    components: list[SBOMComponentResponse]
    issues: list[SecurityIssueResponse]
    started_at: Optional[str] = None
    completed_at: Optional[str] = None


class ScreeningListResponse(BaseModel):
    screenings: list[dict]
    total: int


# =============================================================================
# DEPENDENCY PARSING
# =============================================================================

def parse_package_lock(content: str) -> list[dict]:
    """Parse package-lock.json and extract dependencies."""
    try:
        data = json.loads(content)
    except json.JSONDecodeError:
        return []

    components = []

    # package-lock.json v2/v3 format (packages field)
    packages = data.get("packages", {})
    if packages:
        for path, info in packages.items():
            if not path:  # Skip root
                continue
            name = path.split("node_modules/")[-1] if "node_modules/" in path else path
            version = info.get("version", "unknown")
            if name and version != "unknown":
                components.append({
                    "name": name,
                    "version": version,
                    "type": "library",
                    "ecosystem": "npm",
                    "license": info.get("license", "unknown"),
                })

    # Fallback: v1 format (dependencies field)
    if not components:
        dependencies = data.get("dependencies", {})
        for name, info in dependencies.items():
            if isinstance(info, dict):
                components.append({
                    "name": name,
                    "version": info.get("version", "unknown"),
                    "type": "library",
                    "ecosystem": "npm",
                    "license": "unknown",
                })

    return components


def parse_requirements_txt(content: str) -> list[dict]:
    """Parse requirements.txt and extract dependencies."""
    components = []
    for line in content.strip().split("\n"):
        line = line.strip()
        if not line or line.startswith("#") or line.startswith("-"):
            continue

        # Match patterns: package==version, package>=version, package~=version
        match = re.match(r'^([a-zA-Z0-9_.-]+)\s*([>=<~!]+)\s*([a-zA-Z0-9_.*-]+)', line)
        if match:
            components.append({
                "name": match.group(1),
                "version": match.group(3),
                "type": "library",
                "ecosystem": "PyPI",
                "license": "unknown",
            })
        elif re.match(r'^[a-zA-Z0-9_.-]+$', line):
            components.append({
                "name": line,
                "version": "latest",
                "type": "library",
                "ecosystem": "PyPI",
                "license": "unknown",
            })

    return components


def parse_yarn_lock(content: str) -> list[dict]:
    """Parse yarn.lock and extract dependencies (basic)."""
    components = []
    current_name = None
    for line in content.split("\n"):
        # Match: "package@version":
        match = re.match(r'^"?([^@]+)@[^"]*"?:', line)
        if match:
            current_name = match.group(1).strip()
        elif current_name and line.strip().startswith("version "):
            version_match = re.match(r'\s+version\s+"?([^"]+)"?', line)
            if version_match:
                components.append({
                    "name": current_name,
                    "version": version_match.group(1),
                    "type": "library",
                    "ecosystem": "npm",
                    "license": "unknown",
                })
                current_name = None

    return components


def detect_and_parse(filename: str, content: str) -> tuple[list[dict], str]:
    """Detect file type and parse accordingly."""
    fname = filename.lower()

    if "package-lock" in fname or fname.endswith("package-lock.json"):
        return parse_package_lock(content), "npm"
    elif fname == "requirements.txt" or fname.endswith("/requirements.txt"):
        return parse_requirements_txt(content), "PyPI"
    elif "yarn.lock" in fname:
        return parse_yarn_lock(content), "npm"
    elif fname.endswith(".json"):
        # Try package-lock format
        comps = parse_package_lock(content)
        if comps:
            return comps, "npm"

    # Fallback: try requirements.txt format
    comps = parse_requirements_txt(content)
    if comps:
        return comps, "PyPI"

    return [], "unknown"


# =============================================================================
# SBOM GENERATION (CycloneDX format)
# =============================================================================

def generate_sbom(components: list[dict], ecosystem: str) -> dict:
    """Generate a CycloneDX 1.5 SBOM from parsed components."""
    sbom_components = []
    for comp in components:
        purl = f"pkg:{ecosystem.lower()}/{comp['name']}@{comp['version']}"
        sbom_components.append({
            "type": "library",
            "name": comp["name"],
            "version": comp["version"],
            "purl": purl,
            "licenses": [comp.get("license", "unknown")] if comp.get("license") != "unknown" else [],
        })

    return {
        "bomFormat": "CycloneDX",
        "specVersion": "1.5",
        "version": 1,
        "metadata": {
            "timestamp": datetime.now(timezone.utc).isoformat(),
            "tools": [{"name": "breakpilot-screening", "version": "1.0.0"}],
        },
        "components": sbom_components,
    }


# =============================================================================
# VULNERABILITY SCANNING (OSV.dev API)
# =============================================================================

async def query_osv(name: str, version: str, ecosystem: str) -> list[dict]:
    """Query OSV.dev API for vulnerabilities of a single package."""
    try:
        async with httpx.AsyncClient(timeout=10.0) as client:
            response = await client.post(
                OSV_API_URL,
                json={
                    "package": {"name": name, "ecosystem": ecosystem},
                    "version": version,
                },
            )
            if response.status_code == 200:
                data = response.json()
                return data.get("vulns", [])
    except Exception as e:
        logger.warning(f"OSV query failed for {name}@{version}: {e}")

    return []


def map_osv_severity(vuln: dict) -> tuple[str, float]:
    """Extract severity and CVSS from OSV vulnerability data."""
    severity = "MEDIUM"
    cvss = 5.0

    # Check database_specific for severity
    db_specific = vuln.get("database_specific", {})
    if "severity" in db_specific:
        sev_str = db_specific["severity"].upper()
        if sev_str in ("CRITICAL", "HIGH", "MEDIUM", "LOW"):
            severity = sev_str

    # Derive CVSS from severity if not found
    cvss_map = {"CRITICAL": 9.5, "HIGH": 7.5, "MEDIUM": 5.0, "LOW": 2.5}
    cvss = cvss_map.get(severity, 5.0)

    return severity, cvss


def extract_fix_version(vuln: dict, package_name: str) -> Optional[str]:
    """Extract the fixed-in version from OSV data."""
    for affected in vuln.get("affected", []):
        pkg = affected.get("package", {})
        if pkg.get("name", "").lower() == package_name.lower():
            for rng in affected.get("ranges", []):
                for event in rng.get("events", []):
                    if "fixed" in event:
                        return event["fixed"]
    return None


async def scan_vulnerabilities(components: list[dict], ecosystem: str) -> list[dict]:
    """Scan all components for vulnerabilities via OSV.dev."""
    issues = []

    # Batch: scan up to 50 components to avoid timeouts
    scan_limit = min(len(components), 50)

    for comp in components[:scan_limit]:
        if comp["version"] in ("latest", "unknown", "*"):
            continue

        vulns = await query_osv(comp["name"], comp["version"], ecosystem)

        for vuln in vulns:
            vuln_id = vuln.get("id", f"OSV-{uuid.uuid4().hex[:8]}")
            aliases = vuln.get("aliases", [])
            cve = next((a for a in aliases if a.startswith("CVE-")), None)
            severity, cvss = map_osv_severity(vuln)
            fixed_in = extract_fix_version(vuln, comp["name"])

            issues.append({
                "id": str(uuid.uuid4()),
                "severity": severity,
                "title": vuln.get("summary", vuln_id),
                "description": vuln.get("details", "")[:500],
                "cve": cve,
                "cvss": cvss,
                "affected_component": comp["name"],
                "affected_version": comp["version"],
                "fixed_in": fixed_in,
                "remediation": f"Upgrade {comp['name']} to {fixed_in}" if fixed_in else f"Check {vuln_id} for remediation steps",
                "status": "OPEN",
            })

    return issues


# =============================================================================
# ROUTES
# =============================================================================

@router.post("/scan", response_model=ScreeningResponse)
async def scan_dependencies(
    file: UploadFile = File(...),
    tenant_id: str = Form("default"),
):
    """Upload a dependency file, generate SBOM, and scan for vulnerabilities."""
    if not file.filename:
        raise HTTPException(status_code=400, detail="No file provided")

    content = await file.read()
    try:
        text = content.decode("utf-8")
    except UnicodeDecodeError:
        raise HTTPException(status_code=400, detail="File must be a text-based dependency file")

    # Parse dependencies
    components, ecosystem = detect_and_parse(file.filename, text)
    if not components:
        raise HTTPException(
            status_code=400,
            detail="Could not parse dependencies. Supported: package-lock.json, requirements.txt, yarn.lock",
        )

    # Generate SBOM
    sbom = generate_sbom(components, ecosystem)

    # Scan for vulnerabilities
    started_at = datetime.now(timezone.utc)
    issues = await scan_vulnerabilities(components, ecosystem)
    completed_at = datetime.now(timezone.utc)

    # Count severities
    critical = len([i for i in issues if i["severity"] == "CRITICAL"])
    high = len([i for i in issues if i["severity"] == "HIGH"])
    medium = len([i for i in issues if i["severity"] == "MEDIUM"])
    low = len([i for i in issues if i["severity"] == "LOW"])

    # Persist to database
    screening_id = str(uuid.uuid4())
    db = SessionLocal()
    try:
        db.execute(
            text("""INSERT INTO compliance_screenings
               (id, tenant_id, status, sbom_format, sbom_version,
                total_components, total_issues, critical_issues, high_issues, medium_issues, low_issues,
                sbom_data, started_at, completed_at)
               VALUES (:id, :tenant_id, 'completed', 'CycloneDX', '1.5',
                       :total_components, :total_issues, :critical, :high, :medium, :low,
                       :sbom_data::jsonb, :started_at, :completed_at)"""),
            {
                "id": screening_id,
                "tenant_id": tenant_id,
                "total_components": len(components),
                "total_issues": len(issues),
                "critical": critical,
                "high": high,
                "medium": medium,
                "low": low,
                "sbom_data": json.dumps(sbom),
                "started_at": started_at,
                "completed_at": completed_at,
            },
        )

        # Persist security issues
        for issue in issues:
            db.execute(
                text("""INSERT INTO compliance_security_issues
                   (id, screening_id, severity, title, description, cve, cvss,
                    affected_component, affected_version, fixed_in, remediation, status)
                   VALUES (:id, :screening_id, :severity, :title, :description, :cve, :cvss,
                           :component, :version, :fixed_in, :remediation, :status)"""),
                {
                    "id": issue["id"],
                    "screening_id": screening_id,
                    "severity": issue["severity"],
                    "title": issue["title"][:500],
                    "description": issue.get("description", "")[:1000],
                    "cve": issue.get("cve"),
                    "cvss": issue.get("cvss"),
                    "component": issue["affected_component"],
                    "version": issue.get("affected_version"),
                    "fixed_in": issue.get("fixed_in"),
                    "remediation": issue.get("remediation"),
                    "status": issue["status"],
                },
            )

        db.commit()
    except Exception as e:
        db.rollback()
        logger.error(f"Failed to persist screening: {e}")
    finally:
        db.close()

    # Build response
    sbom_components = []
    comp_vulns: dict[str, list[dict]] = {}
    for issue in issues:
        comp_name = issue["affected_component"]
        if comp_name not in comp_vulns:
            comp_vulns[comp_name] = []
        comp_vulns[comp_name].append({
            "id": issue.get("cve") or issue["id"],
            "cve": issue.get("cve"),
            "severity": issue["severity"],
            "title": issue["title"],
            "cvss": issue.get("cvss"),
            "fixedIn": issue.get("fixed_in"),
        })

    for sc in sbom["components"]:
        sbom_components.append(SBOMComponentResponse(
            name=sc["name"],
            version=sc["version"],
            type=sc["type"],
            purl=sc["purl"],
            licenses=sc.get("licenses", []),
            vulnerabilities=comp_vulns.get(sc["name"], []),
        ))

    issue_responses = [
        SecurityIssueResponse(
            id=i["id"],
            severity=i["severity"],
            title=i["title"],
            description=i.get("description"),
            cve=i.get("cve"),
            cvss=i.get("cvss"),
            affected_component=i["affected_component"],
            affected_version=i.get("affected_version"),
            fixed_in=i.get("fixed_in"),
            remediation=i.get("remediation"),
            status=i["status"],
        )
        for i in issues
    ]

    return ScreeningResponse(
        id=screening_id,
        status="completed",
        sbom_format="CycloneDX",
        sbom_version="1.5",
        total_components=len(components),
        total_issues=len(issues),
        critical_issues=critical,
        high_issues=high,
        medium_issues=medium,
        low_issues=low,
        components=sbom_components,
        issues=issue_responses,
        started_at=started_at.isoformat(),
        completed_at=completed_at.isoformat(),
    )


@router.get("/{screening_id}", response_model=ScreeningResponse)
async def get_screening(screening_id: str):
    """Get a screening result by ID."""
    db = SessionLocal()
    try:
        result = db.execute(
            text("""SELECT id, status, sbom_format, sbom_version,
                      total_components, total_issues, critical_issues, high_issues,
                      medium_issues, low_issues, sbom_data, started_at, completed_at
               FROM compliance_screenings WHERE id = :id"""),
            {"id": screening_id},
        )
        row = result.fetchone()
        if not row:
            raise HTTPException(status_code=404, detail="Screening not found")

        # Fetch issues
        issues_result = db.execute(
            text("""SELECT id, severity, title, description, cve, cvss,
                      affected_component, affected_version, fixed_in, remediation, status
               FROM compliance_security_issues WHERE screening_id = :id"""),
            {"id": screening_id},
        )
        issues_rows = issues_result.fetchall()

        issues = [
            SecurityIssueResponse(
                id=str(r[0]), severity=r[1], title=r[2], description=r[3],
                cve=r[4], cvss=r[5], affected_component=r[6],
                affected_version=r[7], fixed_in=r[8], remediation=r[9], status=r[10],
            )
            for r in issues_rows
        ]

        # Reconstruct components from SBOM data
        sbom_data = row[10] or {}
        components = []
        comp_vulns: dict[str, list[dict]] = {}
        for issue in issues:
            if issue.affected_component not in comp_vulns:
                comp_vulns[issue.affected_component] = []
            comp_vulns[issue.affected_component].append({
                "id": issue.cve or issue.id,
                "cve": issue.cve,
                "severity": issue.severity,
                "title": issue.title,
                "cvss": issue.cvss,
                "fixedIn": issue.fixed_in,
            })

        for sc in sbom_data.get("components", []):
            components.append(SBOMComponentResponse(
                name=sc["name"],
                version=sc["version"],
                type=sc.get("type", "library"),
                purl=sc.get("purl", ""),
                licenses=sc.get("licenses", []),
                vulnerabilities=comp_vulns.get(sc["name"], []),
            ))

        return ScreeningResponse(
            id=str(row[0]),
            status=row[1],
            sbom_format=row[2] or "CycloneDX",
            sbom_version=row[3] or "1.5",
            total_components=row[4] or 0,
            total_issues=row[5] or 0,
            critical_issues=row[6] or 0,
            high_issues=row[7] or 0,
            medium_issues=row[8] or 0,
            low_issues=row[9] or 0,
            components=components,
            issues=issues,
            started_at=str(row[11]) if row[11] else None,
            completed_at=str(row[12]) if row[12] else None,
        )
    finally:
        db.close()


@router.get("", response_model=ScreeningListResponse)
async def list_screenings(tenant_id: str = "default"):
    """List all screenings for a tenant."""
    db = SessionLocal()
    try:
        result = db.execute(
            text("""SELECT id, status, total_components, total_issues,
                      critical_issues, high_issues, medium_issues, low_issues,
                      started_at, completed_at, created_at
               FROM compliance_screenings
               WHERE tenant_id = :tenant_id
               ORDER BY created_at DESC"""),
            {"tenant_id": tenant_id},
        )
        rows = result.fetchall()
        screenings = [
            {
                "id": str(r[0]),
                "status": r[1],
                "total_components": r[2],
                "total_issues": r[3],
                "critical_issues": r[4],
                "high_issues": r[5],
                "medium_issues": r[6],
                "low_issues": r[7],
                "started_at": str(r[8]) if r[8] else None,
                "completed_at": str(r[9]) if r[9] else None,
                "created_at": str(r[10]),
            }
            for r in rows
        ]
        return ScreeningListResponse(screenings=screenings, total=len(screenings))
    finally:
        db.close()