from __future__ import annotations

from datetime import UTC, datetime, timedelta
from uuid import UUID, uuid5

from .models import (
    ComponentRole,
    Criticality,
    DiscoveryCategory,
    HealthStatus,
    ProbeResult,
    Service,
    ServiceKind,
)

DEMO_SCENARIO_NAME = "Northstar Platform"
DEMO_ROOT_CAUSE_NAME = "PostgreSQL"
_DEMO_NAMESPACE = UUID("4b3f31f4-8ee8-4e34-9a30-4bd4e5d4d4c1")


def _stable_id(label: str) -> str:
    return str(uuid5(_DEMO_NAMESPACE, label))


def build_demo_records(now: datetime | None = None) -> tuple[list[Service], list[ProbeResult]]:
    """Build the complete deterministic Northstar topology and its synthetic history."""

    current = now or datetime.now(UTC)
    definitions = [
        ("Public Endpoint", ServiceKind.HTTP, "https://northstar.synthetic/public", None, None, ["Reverse Proxy"]),
        ("Reverse Proxy", ServiceKind.HTTP, "https://northstar.synthetic/proxy", None, None, ["Web Frontend", "Auth Service"]),
        ("Web Frontend", ServiceKind.HTTP, "https://northstar.synthetic/web", None, None, ["API Gateway"]),
        ("Auth Service", ServiceKind.HTTP, "https://northstar.synthetic/auth", None, None, []),
        ("API Gateway", ServiceKind.HTTP, "https://northstar.synthetic/api", None, None, ["PostgreSQL", "Redis"]),
        ("PostgreSQL", ServiceKind.TCP, None, "postgresql.northstar.synthetic", 5432, []),
        ("Redis", ServiceKind.TCP, None, "redis.northstar.synthetic", 6379, []),
        ("Background Worker", ServiceKind.TCP, None, "worker.northstar.synthetic", 9000, ["PostgreSQL", "Redis", "Object Storage"]),
        ("Object Storage", ServiceKind.HTTP, "https://northstar.synthetic/object-storage", None, None, []),
    ]
    ids_by_name = {name: _stable_id(f"service:{name}") for name, *_ in definitions}
    metadata = {
        "Public Endpoint": ("Edge", "Public Gateway", "Edge", ComponentRole.FRONTEND, DiscoveryCategory.PROXY, Criticality.CRITICAL, "Customer-facing availability check", 100.0),
        "Reverse Proxy": ("Edge", "Public Gateway", "Edge", ComponentRole.PROXY, DiscoveryCategory.PROXY, Criticality.HIGH, "Northstar ingress gateway", 100.0),
        "Web Frontend": ("Application", "Northstar App", "Application", ComponentRole.FRONTEND, DiscoveryCategory.APPLICATION, Criticality.HIGH, "Browser application", 99.0),
        "Auth Service": ("Application", "Northstar App", "Application", ComponentRole.API, DiscoveryCategory.APPLICATION, Criticality.HIGH, "Identity and session service", 100.0),
        "API Gateway": ("Application", "Northstar App", "Application", ComponentRole.API, DiscoveryCategory.APPLICATION, Criticality.CRITICAL, "Application API entry point", 99.0),
        "PostgreSQL": ("Data", "Data Platform", "Data", ComponentRole.DATABASE, DiscoveryCategory.DATABASE, Criticality.CRITICAL, "Primary relational datastore", 99.9),
        "Redis": ("Data", "Data Platform", "Data", ComponentRole.CACHE, DiscoveryCategory.CACHE, Criticality.HIGH, "Cache and queue backend", 100.0),
        "Background Worker": ("Application", "Worker Platform", "Application", ComponentRole.WORKER, DiscoveryCategory.BACKGROUND_WORKER, Criticality.HIGH, "Asynchronous job processor", 99.0),
        "Object Storage": ("Data", "Worker Platform", "Application", ComponentRole.STORAGE, DiscoveryCategory.STORAGE, Criticality.MEDIUM, "Durable object store", 100.0),
    }
    services = [
        Service(
            id=ids_by_name[name],
            name=name,
            kind=kind,
            url=url,
            host=host,
            port=port,
            depends_on=[ids_by_name[item] for item in dependencies],
            group=metadata[name][0],
            environment="production",
            application=metadata[name][1],
            domain=metadata[name][2],
            component_role=metadata[name][3],
            category=metadata[name][4],
            criticality=metadata[name][5],
            description=metadata[name][6],
            availability_target=metadata[name][7],
            interval_seconds=60,
            created_at=current - timedelta(days=30),
            updated_at=current,
        )
        for name, kind, url, host, port, dependencies in definitions
    ]

    probes: list[ProbeResult] = []
    for name, *_ in definitions:
        for index in range(24):
            status = _history_status(name, index)
            checked_at = current - timedelta(hours=23 - index)
            latency = None if status == HealthStatus.DOWN else round(42 + ((index * 17 + len(name) * 3) % 120), 2)
            detail = _probe_detail(name, status, index)
            probes.append(
                ProbeResult(
                    id=_stable_id(f"probe:{name}:{index}"),
                    service_id=ids_by_name[name],
                    status=status,
                    latency_ms=latency,
                    detail=detail,
                    checked_at=checked_at,
                    trigger="synthetic",
                    metadata={"scenario": DEMO_SCENARIO_NAME},
                )
            )
    return services, probes


def _history_status(name: str, index: int) -> HealthStatus:
    if name == "PostgreSQL":
        if index in {21, 23}:
            return HealthStatus.DOWN
        if index == 22:
            return HealthStatus.DEGRADED
    if name in {"API Gateway", "Background Worker"} and index == 20:
        return HealthStatus.DOWN
    if name == "Web Frontend" and index == 21:
        return HealthStatus.DOWN
    if name == "Reverse Proxy" and index == 22:
        return HealthStatus.DEGRADED
    return HealthStatus.HEALTHY


def _probe_detail(name: str, status: HealthStatus, index: int) -> str:
    if name == DEMO_ROOT_CAUSE_NAME and status == HealthStatus.DOWN:
        return "Synthetic outage: PostgreSQL connection refused"
    if status == HealthStatus.DOWN:
        return f"Synthetic dependency impact observed at history point {index + 1}"
    if status == HealthStatus.DEGRADED:
        return f"Synthetic elevated latency observed at history point {index + 1}"
    return "Synthetic monitoring observation"