// The network drawn in a .fls file — devices, cables, documentation items —
// read from the decoded JavaBeans graph (javabeans.ts) the way Java FILIUS
// loads it (SzenarioVerwaltung.netzwerkLaden), with the system software
// settings the topology needs (systemSoftware.ts). File systems and
// applications are later layers, which start from `FlsNode.source`.
//
// The result is Java's view, indexed like Java's lists, and is checked
// against Java itself (corpus.java.json). The editor model (node kinds, UUIDs,
// ports as Swift's TopologyPortMetadata, runtime configurations) is built
// from it in a separate step.
//
// Where this departs from filius-ipad's reader, Java is right (plan §13, M2):
//  - the device kind comes from the Java class; the palette label ("Heimrouter")
//    is not file data — Java overwrites it with the class's type name;
//  - a device without coordinates stands at 0,0, as in Java, instead of
//    being dropped;
//  - interface values go through Java's setters (IP.ipCheck for address and
//    mask, upper-cased MAC).

import { isJavaObject, isUnresolved, listItems, simpleClassName, type JavaObject, type JavaValue } from './javabeans.js';
import { javaIpCheck } from '@mdg-filius/core';
import { readSystemSoftware, type FlsSystemSoftware } from './systemSoftware.js';

export type FlsNodeClass = 'Rechner' | 'Notebook' | 'Switch' | 'Vermittlungsrechner' | 'Gateway' | 'Modem';

export interface FlsInterface {
  /** After IP.ipCheck: a canonical dotted quad, or null for text that is not one. */
  ip: string | null;
  mask: string | null;
  /** Upper-cased, as getMac() returns it; undefined when the file has none (Java rolls a random one). */
  mac: string | undefined;
  gateway: string | null;
  dns: string | null;
  /** A notebook's or PC's card joining a switch's wireless network (Betriebssystem.wireless). */
  wireless: boolean;
}

export interface FlsNode {
  javaClass: FlsNodeClass;
  name: string | null;
  x: number;
  y: number;
  /** Hosts only (Rechner, Notebook); false for the others. */
  useIpAsName: boolean;
  useMacAsName: boolean;
  /** A Switch drawn as a cloud (Switch.cloud, the Internet in the examples); false for the others. */
  cloud: boolean;
  /** The interfaces of a Rechner, Notebook, Vermittlungsrechner or Gateway; empty for the others. */
  interfaces: FlsInterface[];
  /** Interfaces, or the ports of a Switch or Modem. */
  portCount: number;
  /** SSIDs, routes, RIP, firewall (systemSoftware.ts). */
  system: FlsSystemSoftware;
  /** The node's JavaBean (`filius.hardware.knoten.*`), for the software layers. */
  source: JavaObject;
}

/** A cable end: the node's index and the port's index on it, as in Java's lists. */
export interface FlsPortReference {
  node: number;
  port: number;
}

export interface FlsLink {
  ends: [FlsPortReference, FlsPortReference];
  wireless: boolean;
  /**
   * The nodes the editor draws the cable between (JCablePanel ziel1, ziel2),
   * by index; null where the file names none.
   */
  panel: [number | null, number | null];
}

export type FlsColor = [red: number, green: number, blue: number, alpha: number];

export interface FlsFont {
  name: string;
  size: number;
  style: number;
}

export interface FlsDocumentationItem {
  /** GUIDocuItem.RECT = 1, TEXT = 2; 0 when the file sets none. */
  type: number;
  text: string | null;
  x: number;
  y: number;
  width: number;
  height: number;
  color: FlsColor | null;
  font: FlsFont | null;
}

export interface FlsTopology {
  /** The version line newer files start with ("Filius version: 1.7.4 (…)"), else null. */
  versionLine: string | null;
  nodes: FlsNode[];
  links: FlsLink[];
  documentation: FlsDocumentationItem[];
  /** What Java would read and this reader could not, and what it left out. */
  warnings: string[];
}

interface NodeClassInfo {
  /** Elements the constructor creates: interfaces (InternetKnoten) or ports (LokalerKnoten). */
  constructed: number;
  local: boolean;
  host: boolean;
  /**
   * The name the constructor gives, in German — the locale Java FILIUS starts
   * in (and the one corpus.java.json was measured with). An English FILIUS
   * would say "Computer" or "Router" here.
   */
  defaultName: string;
}

const NODE_CLASSES: Record<FlsNodeClass, NodeClassInfo> = {
  Rechner: { constructed: 1, local: false, host: true, defaultName: 'Rechner' },
  Notebook: { constructed: 1, local: false, host: true, defaultName: 'Notebook' },
  Vermittlungsrechner: {
    constructed: 1,
    local: false,
    host: false,
    defaultName: 'Vermittlungsrechner',
  },
  Gateway: { constructed: 2, local: false, host: false, defaultName: 'Heimrouter' },
  Switch: { constructed: 24, local: true, host: false, defaultName: 'Switch / WLAN' },
  Modem: { constructed: 1, local: true, host: false, defaultName: 'Modem' },
};

const DEVICE_PACKAGE = 'filius.hardware.knoten.';

function isFlsNodeClass(name: string): name is FlsNodeClass {
  return Object.hasOwn(NODE_CLASSES, name);
}

/** Maps the top-level objects of `konfiguration.xml` to the topology. */
export function readTopology(values: readonly JavaValue[]): FlsTopology {
  const warnings: string[] = [];
  const context = new Reader(warnings);

  // netzwerkLaden: an optional version string, then the node list, the
  // cable list and the documentation list, each by position. A list counts
  // only if its first element has the expected class.
  let position = 0;
  let versionLine: string | null = null;
  if (typeof values[0] === 'string') {
    versionLine = values[0];
    position = 1;
  }
  const nodeItems = listOf(values[position], 'filius.gui.netzwerksicht.GUIKnotenItem');
  const cableItems = listOf(values[position + 1], 'filius.gui.netzwerksicht.GUIKabelItem');
  const documentationItems = listOf(values[position + 2], 'filius.gui.netzwerksicht.GUIDocuItem');

  const nodes: FlsNode[] = [];
  for (const [index, item] of nodeItems.entries()) {
    const node = context.node(item, index, nodes.length);
    if (node !== undefined) {
      if (isJavaObject(item)) context.nodeItems.set(item, nodes.length);
      nodes.push(node);
    }
  }
  const links: FlsLink[] = [];
  for (const [index, item] of cableItems.entries()) {
    const link = context.link(item, index);
    if (link !== undefined) links.push(link);
  }
  const documentation = documentationItems.flatMap((item) => (isJavaObject(item) ? [context.documentation(item)] : []));

  return { versionLine, nodes, links, documentation, warnings };
}

/** The elements of `value` if it is a list whose first element is an object of `className`. */
function listOf(value: JavaValue | undefined, className: string): JavaValue[] {
  const items = listItems(value);
  const first = items[0];
  return isJavaObject(first) && first.className === className ? items : [];
}

class Reader {
  /** Every port object a node owns, to resolve cable ends by identity as Java does. */
  private readonly portOwners = new Map<JavaObject, FlsPortReference>();
  /** Every node item read, to resolve a cable panel's ends. */
  readonly nodeItems = new Map<JavaObject, number>();

  constructor(private readonly warnings: string[]) {}

  node(item: JavaValue, itemIndex: number, nodeIndex: number): FlsNode | undefined {
    const device = isJavaObject(item) ? item.properties.get('knoten') : undefined;
    if (!isJavaObject(device)) {
      this.warnings.push(`node ${itemIndex + 1}: no device (knoten), left out`);
      return undefined;
    }
    const simpleName = simpleClassName(device.className);
    if (!device.className.startsWith(DEVICE_PACKAGE) || !isFlsNodeClass(simpleName)) {
      this.warnings.push(`node ${itemIndex + 1}: unknown device class ${device.className}, left out`);
      return undefined;
    }
    const info = NODE_CLASSES[simpleName];
    const [x, y] = this.position(item as JavaObject, itemIndex);

    const node: FlsNode = {
      javaClass: simpleName,
      name: this.stringProperty(device, 'name', info.defaultName, `node ${itemIndex + 1}`),
      x,
      y,
      useIpAsName: info.host && this.booleanProperty(device, 'useIPAsName', `node ${itemIndex + 1}`),
      useMacAsName: info.host && this.booleanProperty(device, 'useMACAsName', `node ${itemIndex + 1}`),
      cloud: simpleName === 'Switch' && this.booleanProperty(device, 'cloud', `node ${itemIndex + 1}`),
      interfaces: [],
      portCount: 0,
      system: readSystemSoftware(device, simpleName, (message) =>
        this.warnings.push(`node ${itemIndex + 1}: ${message}`),
      ),
      source: device,
    };

    if (info.local) {
      const ports = this.constructedList(device, 'anschluesse', info.constructed);
      node.portCount = ports.length;
      ports.forEach((port, portIndex) => this.ownPort(port, nodeIndex, portIndex));
    } else {
      const networkInterfaces = this.constructedList(device, 'netzwerkInterfaces', info.constructed);
      node.interfaces = networkInterfaces.map((nic, nicIndex) =>
        this.networkInterface(nic, simpleName === 'Gateway' && nicIndex === 0, `node ${itemIndex + 1}`),
      );
      node.portCount = networkInterfaces.length;
      networkInterfaces.forEach((nic, nicIndex) => {
        if (isJavaObject(nic)) this.ownPort(nic.properties.get('port'), nodeIndex, nicIndex);
      });
    }
    return node;
  }

  /**
   * A list property the constructor filled: a getter's result keeps the
   * constructed elements, a list the file sets replaces them.
   */
  private constructedList(device: JavaObject, property: string, constructed: number): JavaValue[] {
    const list = device.properties.get(property);
    // Untouched: the constructed elements, which carry nothing but defaults.
    if (list === undefined) return Array.from({ length: constructed }, () => null);
    return listItems(list, isJavaObject(list) && list.fromGetter ? constructed : 0);
  }

  private ownPort(port: JavaValue | undefined, node: number, index: number): void {
    if (isJavaObject(port) && !this.portOwners.has(port)) this.portOwners.set(port, { node, port: index });
  }

  /**
   * The imageLabel's bounds: fields set one by one in newer files,
   * `new Rectangle(x, y, width, height)` in older ones. Without either, Java's
   * label sits at 0,0.
   */
  private position(item: JavaObject, itemIndex: number): [number, number] {
    const label = item.properties.get('imageLabel');
    const bounds = isJavaObject(label) ? label.properties.get('bounds') : undefined;
    if (!isJavaObject(bounds)) return [0, 0];
    return (['x', 'y'] as const).map((field, index) => {
      const value = bounds.properties.get(field) ?? bounds.args[index] ?? 0;
      if (typeof value === 'number') return value;
      this.warnings.push(`node ${itemIndex + 1}: position ${field} is ${describe(value)}, used 0`);
      return 0;
    }) as [number, number];
  }

  /**
   * NetzwerkInterface as its constructor leaves it, then the file's setters.
   * A Gateway's constructor gives its first interface (WAN) its own address.
   */
  private networkInterface(nic: JavaValue, gatewayWan: boolean, where: string): FlsInterface {
    const result: FlsInterface = {
      ip: gatewayWan ? '42.0.0.10' : '192.168.0.10',
      mask: gatewayWan ? '255.0.0.0' : '255.255.255.0',
      mac: undefined,
      gateway: '',
      dns: '',
      wireless: false,
    };
    if (!isJavaObject(nic)) return result;
    // Only the constructor's own interface gets the WAN address; one the file
    // creates with `new NetzwerkInterface()` starts like any other.
    if (gatewayWan && !nic.fromGetter) {
      result.ip = '192.168.0.10';
      result.mask = '255.255.255.0';
    }
    const at = `${where}, interface`;
    for (const [property, field] of [
      ['ip', 'ip'],
      ['subnetzMaske', 'mask'],
    ] as const) {
      const value = nic.properties.get(property);
      if (value === undefined) continue;
      // setIp(null) throws inside Java's setter; XMLDecoder swallows that and
      // the constructor's value stays.
      if (typeof value === 'string') result[field] = javaIpCheck(value);
      else this.unexpected(at, property, value);
    }
    const mac = nic.properties.get('mac');
    if (typeof mac === 'string') result.mac = mac.toUpperCase();
    else if (mac !== undefined && mac !== null) this.unexpected(at, 'mac', mac);
    for (const [property, field] of [
      ['gateway', 'gateway'],
      ['dns', 'dns'],
    ] as const) {
      const value = nic.properties.get(property);
      if (value === undefined) continue;
      if (typeof value === 'string' || value === null) result[field] = value;
      else this.unexpected(at, property, value);
    }
    const wireless = nic.properties.get('wireless');
    if (typeof wireless === 'boolean') result.wireless = wireless;
    else if (wireless !== undefined) this.unexpected(at, 'wireless', wireless);
    return result;
  }

  link(item: JavaValue, itemIndex: number): FlsLink | undefined {
    const cable = isJavaObject(item) ? item.properties.get('dasKabel') : undefined;
    if (!isJavaObject(cable)) {
      this.warnings.push(`cable ${itemIndex + 1}: no cable (dasKabel), left out`);
      return undefined;
    }
    // Kabel.setAnschluesse(Port[]) in newer files, new Kabel(port, port) in older ones.
    const declared = cable.properties.get('anschluesse');
    const ports = declared === undefined ? cable.args : listItems(declared);
    const ends = ports.map((port) => (isJavaObject(port) ? this.portOwners.get(port) : undefined));
    const [first, second] = ends;
    if (ends.length !== 2 || first === undefined || second === undefined) {
      this.warnings.push(`cable ${itemIndex + 1}: an end is not a port of a device, left out`);
      return undefined;
    }
    const panel = (item as JavaObject).properties.get('kabelpanel');
    const panelEnd = (property: string) => {
      const target = isJavaObject(panel) ? panel.properties.get(property) : undefined;
      return isJavaObject(target) ? (this.nodeItems.get(target) ?? null) : null;
    };
    return {
      ends: [first, second],
      wireless: this.booleanProperty(cable, 'wireless', `cable ${itemIndex + 1}`),
      panel: [panelEnd('ziel1'), panelEnd('ziel2')],
    };
  }

  documentation(item: JavaObject): FlsDocumentationItem {
    const where = 'documentation item';
    const integer = (property: string): number => {
      const value = item.properties.get(property);
      if (value === undefined) return 0;
      if (typeof value === 'number' && Number.isInteger(value)) return value;
      this.unexpected(where, property, value);
      return 0;
    };
    const text = item.properties.get('text');
    return {
      type: integer('type'),
      text: typeof text === 'string' ? text : null,
      x: integer('x'),
      y: integer('y'),
      width: integer('width'),
      height: integer('height'),
      color: this.color(item.properties.get('color'), where),
      font: this.font(item.properties.get('font'), where),
    };
  }

  /**
   * `java.awt.Color` as XMLEncoder writes it: `new Color(r, g, b, a)`. Also
   * `new Color(rgb)` and `new Color(r, g, b)` (ColorUIResource). A component
   * outside 0…255 makes Java's constructor throw — the color stays unset.
   */
  private color(value: JavaValue | undefined, where: string): FlsColor | null {
    if (value === undefined || value === null) return null;
    if (!isJavaObject(value)) {
      this.unexpected(where, 'color', value);
      return null;
    }
    const args = value.args;
    if (!args.every((arg) => typeof arg === 'number' && Number.isInteger(arg))) {
      this.warnings.push(`${where}: color ${value.className} with arguments this reader does not know, left unset`);
      return null;
    }
    const numbers = args as number[];
    if (numbers.length === 1) {
      const rgb = numbers[0]!;
      return [(rgb >> 16) & 0xff, (rgb >> 8) & 0xff, rgb & 0xff, 255];
    }
    if (numbers.length === 3 || numbers.length === 4) {
      const rgba = numbers.length === 3 ? [...numbers, 255] : numbers;
      if (rgba.every((component) => component >= 0 && component <= 255)) return rgba as FlsColor;
      this.warnings.push(`${where}: color component outside 0…255, left unset (as in Java)`);
      return null;
    }
    this.warnings.push(`${where}: color with ${numbers.length} arguments, left unset`);
    return null;
  }

  /** `new Font(name, style, size)`, also as FontUIResource. Java keeps style 0…3 and makes others 0. */
  private font(value: JavaValue | undefined, where: string): FlsFont | null {
    if (value === undefined || value === null) return null;
    const [name, style, size] = isJavaObject(value) ? value.args : [];
    if (
      !isJavaObject(value) ||
      value.args.length !== 3 ||
      (typeof name !== 'string' && name !== null) ||
      typeof style !== 'number' ||
      typeof size !== 'number'
    ) {
      this.unexpected(where, 'font', value);
      return null;
    }
    return { name: name ?? 'Default', size, style: (style & ~0x03) === 0 ? style : 0 };
  }

  private stringProperty(target: JavaObject, property: string, fallback: string, where: string): string | null {
    const value = target.properties.get(property);
    if (value === undefined) return fallback;
    if (typeof value === 'string' || value === null) return value;
    this.unexpected(where, property, value);
    return fallback;
  }

  private booleanProperty(target: JavaObject, property: string, where: string): boolean {
    const value = target.properties.get(property);
    if (value === undefined) return false;
    if (typeof value === 'boolean') return value;
    this.unexpected(where, property, value);
    return false;
  }

  private unexpected(where: string, property: string, value: JavaValue): void {
    this.warnings.push(`${where}: ${property} is ${describe(value)}, ignored`);
  }
}

function describe(value: JavaValue): string {
  if (isUnresolved(value)) return `unresolved (${value.reason})`;
  if (isJavaObject(value)) return `an object of ${value.className}`;
  return JSON.stringify(typeof value === 'bigint' ? String(value) : value) ?? String(value);
}