/**
 * Host Inventory Loader
 * Loads and manages host configuration from YAML files
 */

import { readFileSync, readdirSync, existsSync } from 'fs';
import { join, resolve, dirname } from 'path';
import { parse as parseYaml } from 'yaml';
import type {
  HostConfig,
  NetworkGroup,
  ProvisioningState,
  InventoryIndex,
  HostCapabilities,
} from './types.js';

/**
 * Default inventory path relative to workspace root
 */
const DEFAULT_INVENTORY_PATH = '../../../../../../infrastructure/hosts';

/**
 * Loads and manages host inventory from YAML files
 */
export class HostInventoryLoader {
  private hosts: Map<string, HostConfig> = new Map();
  private hostsByGroup: Map<NetworkGroup, HostConfig[]> = new Map();
  private inventoryPath: string;
  private loaded = false;

  constructor(inventoryPath?: string) {
    if (inventoryPath) {
      this.inventoryPath = inventoryPath;
    } else {
      // Resolve relative to this file's location
      this.inventoryPath = resolve(dirname(import.meta.url.replace('file://', '')), DEFAULT_INVENTORY_PATH);
    }
  }

  /**
   * Load all hosts from the inventory
   */
  async loadAll(): Promise<void> {
    if (this.loaded) {
      return;
    }

    this.hosts.clear();
    this.hostsByGroup.clear();

    await this.loadDirectory(this.inventoryPath);
    this.loaded = true;
  }

  /**
   * Recursively load YAML files from a directory
   */
  private async loadDirectory(dirPath: string, groupPrefix = ''): Promise<void> {
    if (!existsSync(dirPath)) {
      throw new Error(`Inventory path does not exist: ${dirPath}`);
    }

    const entries = readdirSync(dirPath, { withFileTypes: true });

    for (const entry of entries) {
      const fullPath = join(dirPath, entry.name);

      if (entry.isDirectory() && entry.name !== 'schema' && entry.name !== 'provisioning') {
        const newPrefix = groupPrefix
          ? `${groupPrefix}/${entry.name}`
          : entry.name;
        await this.loadDirectory(fullPath, newPrefix);
      } else if (entry.name.endsWith('.yaml') && entry.name !== 'index.yaml') {
        const host = await this.loadHost(fullPath);
        this.hosts.set(host.id, host);

        const group = host.networkGroup;
        if (!this.hostsByGroup.has(group)) {
          this.hostsByGroup.set(group, []);
        }
        this.hostsByGroup.get(group)!.push(host);
      }
    }
  }

  /**
   * Load a single host from a YAML file
   */
  private async loadHost(filePath: string): Promise<HostConfig> {
    const content = readFileSync(filePath, 'utf-8');
    const raw = parseYaml(content);
    return this.transformHost(raw);
  }

  /**
   * Transform raw YAML data to HostConfig
   */
  private transformHost(raw: Record<string, unknown>): HostConfig {
    // Apply defaults and type coercion
    const host: HostConfig = {
      id: raw.id as string,
      hostname: raw.hostname as string,
      fqdn: raw.fqdn as string,
      displayName: (raw.displayName as string) || (raw.hostname as string),
      os: {
        name: (raw.os as Record<string, unknown>).name as HostConfig['os']['name'],
        version: String((raw.os as Record<string, unknown>).version),
        codename: (raw.os as Record<string, unknown>).codename as string | undefined,
        family: (raw.os as Record<string, unknown>).family as HostConfig['os']['family'],
        immutable: Boolean((raw.os as Record<string, unknown>).immutable),
        kernel: (raw.os as Record<string, unknown>).kernel as string | undefined,
      },
      networkGroup: raw.networkGroup as NetworkGroup,
      provider: raw.provider as HostConfig['provider'],
      ssh: {
        host: (raw.ssh as Record<string, unknown>).host as string,
        ip: (raw.ssh as Record<string, unknown>).ip as string | undefined,
        ipv6: (raw.ssh as Record<string, unknown>).ipv6 as string | undefined,
        user: ((raw.ssh as Record<string, unknown>).user as string) || 'root',
        port: ((raw.ssh as Record<string, unknown>).port as number) || 22,
        keyRef: (raw.ssh as Record<string, unknown>).keyRef as string | undefined,
        proxyJump: (raw.ssh as Record<string, unknown>).proxyJump as string | undefined,
      },
      capabilities: this.transformCapabilities(raw.capabilities as Record<string, unknown>),
      provisioningState: (raw.provisioningState as ProvisioningState) || 'unprovisioned',
      provisioningDetails: raw.provisioningDetails as HostConfig['provisioningDetails'],
      hostnameMethod: raw.hostnameMethod as HostConfig['hostnameMethod'],
      alerts: {
        cpuThreshold: ((raw.alerts as Record<string, unknown>)?.cpuThreshold as number) ?? 70,
        cpuThresholdDuration: ((raw.alerts as Record<string, unknown>)?.cpuThresholdDuration as number) ?? 10,
        memoryThreshold: ((raw.alerts as Record<string, unknown>)?.memoryThreshold as number) ?? 70,
        memoryThresholdDuration: ((raw.alerts as Record<string, unknown>)?.memoryThresholdDuration as number) ?? 10,
        diskThreshold: ((raw.alerts as Record<string, unknown>)?.diskThreshold as number) ?? 80,
        gpuThreshold: (raw.alerts as Record<string, unknown>)?.gpuThreshold as number | undefined,
        gpuThresholdDuration: (raw.alerts as Record<string, unknown>)?.gpuThresholdDuration as number | undefined,
      },
      vpn: raw.vpn as HostConfig['vpn'],
      agent: raw.agent as HostConfig['agent'],
      tags: (raw.tags as string[]) || [],
      notes: raw.notes as string | undefined,
    };

    return host;
  }

  /**
   * Transform capabilities with defaults
   */
  private transformCapabilities(raw: Record<string, unknown> | undefined): HostCapabilities {
    if (!raw) {
      return {
        gpu: false,
        database: false,
        storage: false,
        vpnGateway: false,
        dnsServer: false,
        services: [],
      };
    }

    return {
      gpu: Boolean(raw.gpu),
      gpuModel: raw.gpuModel as string | undefined,
      database: Boolean(raw.database),
      databaseType: raw.databaseType as HostCapabilities['databaseType'],
      storage: Boolean(raw.storage),
      storageCapacityGB: raw.storageCapacityGB as number | undefined,
      vpnGateway: Boolean(raw.vpnGateway),
      dnsServer: Boolean(raw.dnsServer),
      services: (raw.services as string[]) || [],
    };
  }

  /**
   * Get a host by ID
   */
  getHost(id: string): HostConfig | undefined {
    return this.hosts.get(id);
  }

  /**
   * Get hosts by network group
   */
  getHostsByGroup(group: NetworkGroup): HostConfig[] {
    return this.hostsByGroup.get(group) || [];
  }

  /**
   * Get all hosts
   */
  getAllHosts(): HostConfig[] {
    return Array.from(this.hosts.values());
  }

  /**
   * Get hosts by capability
   */
  getHostsByCapability<K extends keyof HostCapabilities>(
    capability: K,
    value: HostCapabilities[K] = true as HostCapabilities[K]
  ): HostConfig[] {
    return this.getAllHosts().filter(h => h.capabilities[capability] === value);
  }

  /**
   * Get hosts by provisioning state
   */
  getHostsByProvisioningState(state: ProvisioningState): HostConfig[] {
    return this.getAllHosts().filter(h => h.provisioningState === state);
  }

  /**
   * Get hosts by tag
   */
  getHostsByTag(tag: string): HostConfig[] {
    return this.getAllHosts().filter(h => h.tags.includes(tag));
  }

  /**
   * Get hosts that need provisioning
   */
  getHostsNeedingProvisioning(): HostConfig[] {
    return this.getAllHosts().filter(
      h => h.provisioningState === 'unprovisioned' || h.provisioningState === 'minimal'
    );
  }

  /**
   * Get hosts with issues
   */
  getDegradedHosts(): HostConfig[] {
    return this.getAllHosts().filter(h => h.provisioningState === 'degraded');
  }

  /**
   * Get VPS hosts only
   */
  getVPSHosts(): HostConfig[] {
    return this.getAllHosts().filter(
      h => h.networkGroup.startsWith('dss/')
    );
  }

  /**
   * Get local/homelab hosts only
   */
  getHomelabHosts(): HostConfig[] {
    return this.getHostsByGroup('voyager');
  }

  /**
   * Load the inventory index
   */
  async loadIndex(): Promise<InventoryIndex | null> {
    const indexPath = join(this.inventoryPath, 'index.yaml');
    if (!existsSync(indexPath)) {
      return null;
    }

    const content = readFileSync(indexPath, 'utf-8');
    return parseYaml(content) as InventoryIndex;
  }

  /**
   * Reload the inventory (force refresh)
   */
  async reload(): Promise<void> {
    this.loaded = false;
    await this.loadAll();
  }

  /**
   * Check if inventory is loaded
   */
  isLoaded(): boolean {
    return this.loaded;
  }

  /**
   * Get inventory path
   */
  getInventoryPath(): string {
    return this.inventoryPath;
  }
}

/**
 * Create a singleton loader instance
 */
let defaultLoader: HostInventoryLoader | null = null;

/**
 * Get the default loader instance
 */
export function getDefaultLoader(inventoryPath?: string): HostInventoryLoader {
  if (!defaultLoader || inventoryPath) {
    defaultLoader = new HostInventoryLoader(inventoryPath);
  }
  return defaultLoader;
}

/**
 * Initialize and load the default inventory
 */
export async function initializeInventory(inventoryPath?: string): Promise<HostInventoryLoader> {
  const loader = getDefaultLoader(inventoryPath);
  await loader.loadAll();
  return loader;
}